Chapter 1
1-A
Environmental Interrelationships
TRUE-FALSE QUESTIONS
Where "F" is your answer, change the underlined portion (and the underlined
portion only) of the statement to make it true.
1. The official name of the 1992 Rio de Janeiro Earth Summit is the World
Conference on the Environment.
2. An ecosystem is a dynamic complex of plants, animals, microorganisms and
their physical environment interacting and functioning as an essentially
self-sustaining unit.
3. Soil erosion leads to siltation of rivers, which in turn may lead to fish
kill.
4. The use of pesticides in agriculture often results in both surface water
and groundwater pollution.
5. Natural ecosystems do not require material input or energy input to sustain
themselves.
6. In an ecosystem, a living organism interacts with other organisms but not
with the physical components of the environment.
7. Through bioaccumulation, toxic chemicals that are very dilute in the
environment can reach dangerously high concentrations in the fatty
tissues and organs of fish, mammals and birds.
8. The excessive growth of algae in rivers and lakes is often due to inputs of
calcium and carbon from farmland runoff and sewage treatment plant
outfall.
9. A smokestack is an example of a point source of pollution.
10. The loss of old-growth forests is one of the major environmental concerns
in the Dry West of Canada.
1-B
MATCHING QUESTIONS
Match each of Q.1-7 with the most appropriate item from the following list.
Any item in the list may be used more than once, or not at all.
a. Wilderness North
b. Agricultural Middle
c. Dry West
d. Forested
West
e. Great Lakes and Industrial NE
f. Diverse South
g. edge
effect
1. Long-term use of irrigated lands in this region often results in the
buildup of salts in the soil.
2. This region has the most fragile and vulnerable ecosystems of all.
Page 1
3. Old-growth forests are being logged here.
4. Soil erosion and groundwater pollution are common in this region.
5. It develops when a large forest is carved up and divided into smaller
patches.
6. Loss of wetlands and salt water intrusion are causes for concern in this
region.
7. Industry in this region is the main source of acid deposition and toxic
wastes in the environment.
1-C
MULTIPLE-CHOICE QUESTIONS
1. Environmental problems are difficult to resolve mainly because
a. the
problems are technically too complex.
b. they are interrelated with
societal issues like jobs and growth.
c. the required anti-pollution
equipment is not commercially available.
d. industries continue to
pollute.
2. In an ecosystem, all components
with
c. act independently of
each other.
a. help
d. interact with
b. compete
3. Which of the following statements about the IJC is false?
a. It was
established in 1909.
b. It remains to be a major scientific
organization today.
c. It plays a major role in Great Lakes water
quality issues.
d. Its full name is Interprovincial Joint Commission.
4. From the ecological point of view, old-growth forests ought to be preserved
mainly because these forests
a. contain trees that are old and special.
b. support rare species of birds.
c. serve as the habitats for
unique, diverse communities.
d. provide us with more oxygen and help
reduce the greenhouse effect.
5. If PCB concentrations in phytoplankton in a lake are in the neighborhood of
0.002 ppm (parts per million) while PCB concentrations in lake water are
200 times lower, you would attribute the effect to
a. biomagnification.
b. bioaccumulation.
c. biodegradation.
d. biogeneration.
6. All of the following statements about ecosystems are true EXCEPT:
a. Ecosystems refer to the physical components of the environment.
b. Ecosystems may be large or small in size.
c. Lake Erie is an
ecosystem. d. Ecosystem boundaries may or may not be distinct.
7. Environmental science is
a. another term for ecology.
b. based on
physics and chemistry alone.
c. a subdivision of biology.
d. an
interdisciplinary science.
8. The Wilderness North is
environmental assault.
a. insensitive to
b. resilient to
c. vulnerable to
d. unspoiled by
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9. The region referred to as the Agricultural Middle in your text encompasses
parts of
in Canada.
a. Ontario
b. Ontario and Quebec
c.
Manitoba and Saskatchewan
d. Alberta, Saskatchewan and Manitoba
10. The northern spotted owl has become an endangered species because of
a. toxic chemicals in their food.
b. competition from another species.
c. habitat alteration/destruction.
d. hunting by humans.
1-D
QUESTIONS FOR REVIEW, RESEARCH AND CRITICAL THINKING
1. Ecosystems are often characterized as self-sustaining and self-regulating.
What do these words mean? Explain in terms of energy inputs, material
cycles and ecosystem interactions.
2. On the premise that all ecosystems are self-sustaining and self-regulating,
determine which of the following are ecosystems: (a) a home aquarium, (b)
Metropolitan Toronto, (c) Lake Ontario, (d) the planet Earth. Do
ecosystems have time scales associated with them? Discuss.
3. List three major environmental problems that are of national significance,
and another three that are of global significance. Briefly explain why
you consider each to be a serious problem, and describe what you as an
individual can do to help alleviate it.
4. There are different approaches to solving environmental problems. Using
the solid waste (generation and disposal) problem as an example, propose
solutions based respectively on (a) an ecosystem approach, (b) a
technology approach, (c) an economics approach, (d) a legislation
approach. Are these approaches mutually exclusive? Which of these would
be the approach of your choice, and why?
5. Why are we faced with so many serious environmental problems today? Is it
largely because of a lack of political will and leadership at different
levels of government? A disregard for public welfare on the part of
industry and business? A lagging anti-pollution technology and
scientific know-how? Existing economic and legal structures that are
environmentally unsound and unfriendly? A world population that keeps
growing and consuming more resources?... Is there a root cause? If so,
identify it and justify your answer.
6. Using ideas derived from the ecosystem approach, compare electric cars and
gasoline cars with respect to their impact on air pollution. Did
electric cars come out clear winners in this comparison? Elaborate.
7. In the early 1950s eutrophication was emerging as a serious pollution
problem in Lake Erie.
(a) What does eutrophication mean, literally and generally?
(b)What processes and what chemicals were responsible for the
eutrophication in Lake Erie?
(c)Algal blooms were cited as one consequence of the eutrophication
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problem. What was the reason for the blooms to occur?
(d)Oxygen depletion was cited as another consequence of the
eutrophication. Where was the oxygen depletion occurring - in the
surface waters or bottom waters? And why would more algae (which
are plants that release oxygen) in the Lake subsequently result in a
depletion of dissolved oxygen in the water?
(e)Is eutrophication still a serious pollution problem in Lake Erie today?
In the other Great Lakes? And in smaller lakes such as those in
Ontario's cottage country? Comment.
8. Distinguish between bioaccumulation and biomagnification (also known as
biological amplification). Why are persistent toxic chemicals such as
PCBs often linked with bioaccumulation and biomagnification?
9. (a)The public has been advised by health agencies against eating very
large trout from all five lakes. Why? If consumption of very large
trout is to be avoided, should consumption of very large fish of
other species be avoided as well? Explain.
(b)Suppose a 2-kg lake trout caught from one area of Lake Ontario contains
4 mg of PCBs. Guesstimate the number of milligrams of PCBs in a 5kg lake trout taken from the same area of the Lake. Would it be
close to 10 mg, considerably less than 10 mg, or considerably more
than 10 mg? Give your reasoning.
10.
Name three main environmental issues that were examined and discussed at
the 1992 Earth Summit.
11.
Compare environmental science and traditional science (e.g. biology,
chemistry and physics). What are the major similarities and differences?
1-E
WORKING WITH NUMBERS AND GRAPHS
1. Some quantities encountered in environmental science appear so enormous or
so minuscule as to "boggle the mind." What general strategy would you
suggest to render such quantities more meaningful? Illustrate your
strategy by applying it to each of the following:
(a)Amount of water in the atmosphere: 1.3 x 1013 m3
(b)Global energy demand (1990): 3.9 x 1020 J(oules) per year
(c)Dioxin concentration in lake trout from Lake Ontario (1987): 38 ppt
(parts per trillion)
(d)Groundwater flow rate in a certain aquifer: 5 x 10-7 m/s
(e)Canada's prime agricultural land area (1980s): 4.8 x 1011 m2
(f)Worldwide topsoil loss (1990s): 23 billion tonnes per year
2. Few areas of basic mathematics are as widely used - and misused - in
everyday life (and in environmental studies) as percent figures and
percent calculations. When working with such figures and calculations,
what basic rules should you be mindful of? What common pitfalls should
you attempt to avoid?
3. Parts per million (ppm) and parts per billion (ppb) are often used as units
for measuring pollutant concentrations. What exactly do these units
Page 4
represent? What ambiguities over the meaning of these units may
sometimes arise? How are these units related to percent?
Page 5
Chapter 1
Answers and Solutions
1-A
T:
F:
Q.2, 3, 4, 7, 9
Q.1, 5, 6, 8, 10
Q.1
United Nations Conference on Environment and Development
Q.5
material input
Q.6
and with the physical components of the environment
Q.8
phosphates and nitrates
Q.10 in the Forested West of Canada
1-B
1c
2a
3d
4b
1-C
1b
2d
3d
4c
5g
5b
6f
6a
7e
7d
8c
9d
10c
1-D
1. Ecosystems are self-sustaining with respect to materials only. They do
need energy inputs. Materials within ecosystems are continually cycled,
and therefore supplies from outside are not needed. But the same can not
be said about energy.
Ecosystems are self-regulating in the sense that interactions within an
ecosystem tend to moderate excesses in either the positive or negative
direction, thereby gradually restoring balance to the ecosystem.
2. All except Metro Toronto fulfill the requirements of self-sustaining and
self-regulating, and hence are ecosystems.
Though not normally specified as such, ecosystems do have time scales
associated with them. A small lake, for example, is an ecosystem only to
the extent that a time scale of centuries is used.
3. Any reasonable answer is acceptable, e.g. acid deposition, toxic chemicals
in Great Lakes waters and destruction of old-growth forests as national
environmental problems; global warming, stratospheric ozone depletion and
world population growth as global environmental problems.
Some ways an individual can help include being a lifelong student-teacher
of environmental education; adopting a lifestyle of minimal environmental
impact; and actively supporting environmental groups that promote
sustainable development, restructuring of the economy, biodiversity
preservation, population stabilization, pollution reduction and control,
and other fundamental solutions to ultimate global environmental
problems.
4. (a)Ecosystem approach: Practice the 3Rs.
(b)Technology approach: Use state-of-the-art high-efficiency incinerators.
(c)Economics approach: Impose surcharge on households with excessive
garbage.
(d)Legislation approach: Require the use of recyclable containers. These
approaches are not mutually exclusive - they could be used
concurrently to complement each other. However, solutions based on
technology, economics and legislation generally tend to be narrowly
focused and neglect the big picture. For that reason, solutions
Page 6
based on an ecosystem approach would be preferable.
5. While we all love to put the blame on government, industry or the system,
we are the root cause. We need an environmentally correct worldview and
value system that translate into actions, lifestyle changes and new
priorities.
6. If one looks at the big picture, one would find that electric cars are not
"pollution-free." The electrical energy that propels these cars comes
from electric power plants, most of which get their energy from burning
coal or oil. So while the electric cars themselves may not emit any air
pollutants, the power plants do. Perhaps insofar as air pollution is
concerned, the dubious advantage of electric cars is that it changes the
nature and location of the pollution: from photochemical smog in urban
areas to acid deposition in neighboring regions.
7. (a)The word means good nutrition literally; in common usage, it refers to
the overfertilization of a body of water by plant nutrients,
resulting in abundant algae growth and oxygen deficiency in the
water.
(b)The chemicals were phosphates and (to a lesser extent) nitrates. They
entered the Lake as runoff from farmland and as effluent from sewage
treatment plants.
(c)Phosphorus is usually the limiting factor in lake waters. As Lake Erie
waters became overenriched with phosphates, the limiting factor was
removed and algal bloom followed.
(d)Oxygen depletion was occurring in bottom waters where dead algae had
accumulated. The dead algae didn't directly cause the oxygen
depletion; the bacteria that were breaking them down did.
(e)Eutrophication is no longer a serious pollution problem in Lake Erie,
nor is it in the other Great Lakes. However, eutrophication is a
problem or emerging as a problem in some smaller lakes such as Lake
Simcoe in Ontario. The reason: sewage treatment facilities have not
caught up with population growths in the area.
8. Bioaccumulation refers to the buildup over time of toxic chemicals in the
bodies of organisms (at a particular trophic level). Biomagnification
refers to the increase in the concentration levels of these chemicals in
organisms at a higher trophic level.
They are ubiquitous in the environment; they are very persistent and
nonbiodegradable. Once ingested by an organism, they tend to accumulate
in the fatty tissues of the body and build up to higher and higher
levels. They then move up the food chain, resulting in biomagnification.
9. (a)Large trout have been found to contain levels of toxic chemicals higher
than the maximum allowable concentrations, hence the advisories.
Yes, as a general rule, consumption of very large fish of any
species should be avoided.
(b)One should expect the 5-kg lake trout to contain considerably more than
10 mg of PCBs. Other factors being equal, the amount of toxic
chemicals accumulated in the body is roughly proportional to the
total amount of food consumed. As the age of the 5-kg trout is
likely to be more than 2.5 times that of the 2-kg trout, and the
Page 7
daily amount of food required by the larger fish is likely to be
higher than that required by the smaller fish, one should expect
that the cumulative amount of food consumed by the 5-kg trout is
much more than 2.5 times that consumed by the 2-kg trout.
10.
Global climate change and greenhouse gas emissions, global deforestation,
and the protection of biodiversity.
11.
Similarities: Same physical and biological laws and principles; same
analytical and data-based approach; same green planet and
life thereof to study.
Differences:
Environmental science is multidisciplinary and holistic;
environmental science is a "soft" science; environmental
science offers few perfect, ultimate solutions.
1-E
1. Divide (say by the world's population to make the number smaller), multiply
(say by 1000 years to make the number larger), or somehow manipulate the
number under consideration so as to link it with more familiar quantities
or situations in our everyday life.
(a)It's about the same amount of water as contained in Lake Superior.
(b)It translates into about 11 barrels of oil per person per year
(c)You would need about 20 million lake trout to get just one spoonful of
dioxin.
(d)It would take the groundwater a whole year just to move through a
distance of 16 m.
(e)It's slightly more than half the size of Ontario.
(f)It's tantamount to losing all of the topsoil on about 5 million
hectares of land, an area the size of Nova Scotia.
2. Basic rules:
a. Know the base. A figure like 5% is meaningless unless we know it's 5%
of what. (A very small % figure may actually represent a huge
quantity, and vice versa.) As any of the attributes, like sex,
volume, weight, etc., of a given organism or physical quantity may
be used as the base, the resulting % figure obviously depends on the
choice of the base. Thus, if you are one of a group of one hundred
people, by body count, you make up 1% of the group, but by body
weight, you may not be 1%. As another example, "71% of the Earth is
water" (as stated in some textbooks) can be a really confusing
statement, when "71% of the Earth's surface is covered by water" is
meant.
b. In computations involving %, use the decimal equivalent instead. Thus,
rewrite 1.5% as 0.015 before doing a calculation on it.
c. Constituent parts should add up to 100%.
Pitfalls:
a. Be wary when additions or subtractions involving percents are
performed, or when comparisons of them are made. If the base is not
the same, then 1% of this simply isn't the same as 1% of that. For
example, if the annual population increases of a certain city in
five consecutive years are respectively 1.0%, 0.7%, 1.3%, 1.2%, and
Page 8
0.8%, the total population increase for the 5-year period is not
5.0% (of the initial population).
b. When interpreting cumulative percent changes (e.g. "Tailpipe emissions
of nitrogen oxides have been reduced by 75%."), ask questions like
"Since when?", "Compared to what?" and "In absolute numbers, how
large a quantity is it?" (For the above statement, the pertinent
question might be: On average, how large a quantity of nitrogen
oxides is still being emitted per car per kilometer driven?)
c. The kinds of growth we encounter in environmental studies are mostly of
the compound growth type. Therefore, when figuring out the rate or
the amount of growth, one has to use the compound interest formula
or the exponential increase formula, rather than the simple interest
formula.
3. Parts per million and parts per billion are simply extensions of parts per
hundred (percent). 5 ppm, for example, means five parts of a certain
pollutant/substance per 1,000,000 parts of polluted water (or air, or
soil, or whatever). Occasionally, ambiguities arise over the meaning of
parts. Is it grams, liters, the number of molecules, or what that are
being used for counting and comparing? A common but not universal
practice is to use mass units for counting in work involving liquids and
solids, and to use volume units for counting in work involving gases.
To change from % to ppm, multiply the % value by 10,000. To change from %
to ppb, multiply the % value by 10,000,000.
Page 9
Chapter 2
2-A
Environmental Ethics
TRUE-FALSE QUESTIONS
Where "F" is your answer, change the underlined portion (and the underlined
portion only) of the statement to make it true.
1.The planet Earth can be aptly described as an open ecosystem.
2.Each working part of the Earth is interdependently connected to all the
other working parts.
3.Environmental issues involve a consideration of ethics but not morals.
4.The concept of humans being superior to nature is part of the JudeoChristian tradition.
5.Recent surveys indicate that most Americans believe it is drivers, not
cars, that pollute.
6.The first Earth Summit organized by the United Nations was held in Rio de
Janeiro in 1992.
7.Economic growth and resource exploitation have long been regarded by most
people as necessary and beneficial to humankind.
8. Individuals, like governments and corporations, are part of the
environmental problem, as well as part of the solution.
9.Most Canadians and Americans want the environment cleaned up, and are
prepared to make major lifestyle changes to make that happen.
10.Radical environmentalists tend to be anthropocentric rather than
biocentric.
2-B
MATCHING QUESTIONS
Match each of Q.1-7 with the most appropriate item from the following list.
Any item in the list may be used more than once, or not at all.
a. UNCED
b. conservation ethic
c. development ethic
d. preservation
ethic
e. North and South
f. Aldo Leopold
g. David Thoreau
h.
Rachel Carson
1.Bigger is better.
2.A balance between total development and absolute preservation.
3.A Sand County Almanac.
4.More developed countries and less developed countries.
5.The Earth Summit.
Page 10
6.Nature is special and must be protected, no matter what the social or
economic costs are.
7.Walden Pond.
2-C
MULTIPLE-CHOICE QUESTIONS
1.The conservationist of yesterday has reemerged today as the
a. social
ecologist.
b. deep ecologist.
c. preservationist.
d. naturalist.
2.An anthropocentric person would
a. consider humans as being plain members
of a biotic community.
b. value the health of the Earth above economic
growth.
c. hold humans above other living things.
d. hold a reverence
for other forms of life.
3.Economic growth and resource exploitation are attitudes
a. deeply
embedded in developed countries only.
b. deeply embedded in less
developed countries only. c. shared by both developed and less developed
countries. d. condemned by both developed and less developed countries.
4. Agenda 21, as adopted at the 1992 Earth Summit, was so named because
a. the action plan was endorsed by 21 countries.
b. it contained 21
specific environmental principles.
c. it was adopted by all member
countries of the UN on June 21, 1992.
d. it provided an agenda for
well-defined environmental programs into the 21st century.
5.International agreements achieved at the 1992 Earth Summit included all of
the following EXCEPT
a. The Rio Declaration on Environment and
Development.
b. a convention on marine overfishing.
c. a convention
on climate change.
d. a convention on biodiversity.
6.Which of the following statements about the 1992 Earth Summit is false?
a. It was the first Earth Summit ever organized by the UN.
b. It was
attended by more than 100 heads of state.
c. It was intended to promote
better integration of nations' environmental goals with their economic
aspirations.
d. Its official name was the United Nations Conference on
Environment and Development.
7.Which of the following statements about Canada's Green Plan is not true?
a. It was first released in December, 1990.
b. It is a set of
comprehensive environmental action plans that are legally binding on
Canadian industries.
c. It advocates the concept of sustainable
development.
d. It contains initiatives to reduce waste generation and
energy use.
8.In its 1996 annual report, World Wildlife Fund Canada compared and ranked
the various provincial governments on progress made in ecological
protection. Which of the following groupings gives the correct order,
from best to worst?
a. Ontario, Quebec, British Columbia, Alberta.
b. British Columbia, Alberta, Manitoba, Ontario.
c. New Brunswick,
Newfoundland, Nova Scotia, Prince Edward Island.
d. Quebec, Ontario,
Page 11
Nova Scotia, British Columbia.
9.Canada's environmental industry sector is composed of companies involved in
a. water and air pollution control.
b. recycling and toxic waste
management.
c. environmental law, environmental audit and environmental
assessment.
d. all of the above, plus many others like packaging,
energy conservation, renewable resource management, soil and sediment
remediation, pollution prevention, and so on.
10.The collapse of the cod fishery off Canada's east coast in the early 1990s
was mainly the result of years of
a. foreign overfishing.
b.
overfishing by Canadian fishermen.
c. heavy pollution.
d. southward progression of the cold Labrador Current.
2-D
QUESTIONS FOR REVIEW, RESEARCH AND CRITICAL THINKING
1. Despite deep environmental concerns expressed by the public in recent
years, progress on the environmental front has been slow in that few
people have actually made the necessary lifestyle changes to bring about
improvements in environmental quality. In North America, for example,
most people are still driving to and from work.
(a)Suggest reasons why people still choose to use their private cars to
get to and from work.
(b)What would have to happen before most people would give up their cars
as a means of transportation to work?
(c)Taking it one step further, what measures do you believe our political
leaders should implement in order to motivate the public to give up
other environmentally unsound practices (e.g. the excessive use of
water, chemical fertilizers, pesticides and herbicides on their
lawns)?
2. "Finance ministers, not environment ministers, have the power to save the
world's environment."
(a) Paraphrase the above quote.
(b) Do you agree with the above statement? Why or why not?
3. Dire predictions of impending environmental calamities notwithstanding, the
world today appears to be better off than ever before by some measures for example, in life expectancy, grain production, and international
agreements on environmental protection. Are gloomy predictions of
environmental disasters largely gross exaggerations? Are human ingenuity
and resourcefulness more than enough to solve current and future
environmental problems? Can we continue to conduct business as usual
with the expectation that environmental apocalypse is nowhere in sight?
Discuss.
4. What do you see as the connection between economic development and the
quality of the environment? In particular, how would the growth and
development currently taking place in some developing countries (e.g.
China and Thailand) impact on their own environment and the global
environment? What are the ramifications for the developed countries?
Page 12
5. The recession of the early 1990s in North America appears to have taken its
toll on the environmental movement, as witnessed by the declining number
of green products on the market, the high percentage of green magazines
that have gone out of business, and the lower profile of
environmentalists as a political force. Are people getting tired of
hearing gloomy messages on the environment day after day? Do you see
this as the beginning of a downward trend in public interest in the
environment? As we move toward the 21st Century, whither goes the
environmental movement? Elaborate.
6. More than a quarter century has passed since Earth Day began in 1970. In
Canada, what gains in environmental protection have been made? What
areas require immediate attention and improvement? Overall, how does
Canada's environmental record compare with those of other industrialized
nations of the world?
7. In terms of the strategy they use to bring about change and resolution, how
are Canada's environmental activists today different from their
counterparts two or three decades ago?
2-E
WORKING WITH NUMBERS AND GRAPHS
1. The exponential function is a fundamental mathematical concept to grasp in
the study of the environment. Why? Express the function mathematically.
What does its graph look like? In the context of environmental studies,
what is the single most important characteristic of this function?
2. Assume that pollution levels
inputs are stopped. If it
level to drop from 100% to
pollution level to drop to
in lakes decrease exponentially once pollutant
takes two years for Lake Ontario's pollution
65%, how many more years will it take for the
25% of its initial concentration?
Page 13
Chapter 2
Answers and Solutions
2-A
T: Q.2, 4, 7, 8
F: Q.1, 3, 5, 6, 9, 10
Q.1 a closed ecosystem
Q.3 both ethics and morals
Q.5 cars, not drivers
Q.6 Stockholm, Sweden in 1972
Q.9 but are not prepared to make major lifestyle changes
Q.10
biocentric rather than anthropocentric
2-B
1c
2b
3f
4e
5a
6d
7g
2-C
1a
2c
3c
4d
5b
6a
7b
8b
9d
10b
2-D
1. (a)A number of reasons could be cited, such as convenience, sense of
mobility and privacy, lower travel costs, shorter travel times,
inadequate or nonexistent public transit facilities, and social
acceptance of the practice of driving to work.
(b)People would probably give up their cars if on the one hand, driving to
work became very inconvenient, time-consuming, expensive and
socially unacceptable; and on the other hand, improved and extended
transit service would be available. Over the longer term,
population increases and urban sprawl would have to be halted or
reversed.
(c)It is probably unrealistic to expect people to initiate the necessary
lifestyle changes entirely on their own (except perhaps for the
ultra greens). Hopefully our political leaders would have the
courage and foresight to implement a mix of economic (e.g. in the
form of incentives and disincentives), regulatory (e.g. in the form
of guidelines, restrictions and bans), and suasive (e.g. public
campaigns and education programs, and provision of needed service)
measures designed to motivate the public to embrace environmentally
sound practices.
2. (a)To save the environment, it's not rhetoric but changes in our
consumption habits and manufacturing processes as well as new
investments in environmental improvement that count. In the real
world, whether these changes actually occur depend to a large extent
on fiscal policies and economic considerations, hence the above
statement.
(b)The statement is mostly true, but we would hope that economic
considerations are not the only determinant in all phases of our
environmental decision-making. After all, many aspects of the
environment cannot be measured in terms of dollars and cents alone.
3. By selective use of available data, and depending on how one defines
"progress," our world can indeed be made to appear much better off today
than ever before. To be sure, some overly gloomy predictions of imminent
Page 14
environmental disasters are premature and unwarranted, but if we look at
the big picture and take the longer-term view, we'll be forced to
conclude that we just cannot "conduct business as usual" without
incurring environmental calamities somewhere down the road. Our current
lifestyle is simply unsustainable.
4. Economic development and the state of the environment are inseparable. In
most cases, economic development in developing countries has intensified
and accelerated environmental degradation in these countries (and
globally as well), as more energy, water and other resources are used,
and more pollutants and wastes are generated. However, if properly
managed, economic development could be made less harmful to the
environment, or perhaps could even provide the needed impetus for
environmental improvements (and Singapore is an example of that). In
this regard, there is much the developed countries could offer to the
developing countries in terms of financial assistance, technology
transfer, resource management, wealth redistribution and other areas of
international cooperation.
5. The recession has been long and deep, and when people are preoccupied with
jobs and the economy, it is perhaps only natural that environmental
concerns should take a back seat to other more pressing problems.
However, this temporary setback should in no way be regarded as the
impending demise of the environmental movement. The sheer magnitude and
scope of global, national and local environmental issues simply do not
allow themselves to be ignored by us. The environmental movement is here
to stay, and will in all likelihood grow in importance and influence as
we move toward the 21st Century.
6. Some of the modest gains that have been made include:
- public awareness of environmental issues;
- the formation of various environmental organizations;
- the setting up of federal and provincial ministries of the environment,
along with environmental legislation and environmental assessment
procedures;
- reductions in sulfur dioxide emissions, and in the effluents of some
chemicals;
- extending sewage treatment to more municipalities; and
- the paper/aluminum cans/bottles recycling program.
But these modest gains have been more than offset by Canada's wasteful use
of energy and water, high solid waste production, poor management of
toxic wastes, excesses in fertilizer and pesticide use, unsustainable
logging practices, and failures to protect natural areas. Overall,
Canada's environmental record is among the worst, if not the worst, of
the industrialized nations of the world, according to studies released by
both the OECD experts and the Washington-based National Center for
Economic Alternatives in 1995, and by the World Wildlife Fund in 1996.
7. Environmental activists of today are probably more pragmatic, more
sophisticated and more solutions-oriented than their counterparts of
yesteryear. They have not shied away from confrontational tactics, but
they would not hesitate to work with industry or business either in order
to find viable alternatives or solutions to environmental problems.
Page 15
Rather than simply drawing attention to problems or attacking the system,
they would now collaborate with government agencies, industry, the
scientific community and mainstream organizations to spearhead change.
2-E
1. Basically because a large number of real-world phenomena can be described
fairly accurately by the exponential function. The general form of the
exponential function f(x) is given by
f(x) = ax
where a is the base (a greater than 0 and not equal to 1).
As an example, 2x is an exponential function, as is e(0.01)(x) (where
e
= 2.7183 is the base of the natural exponential function). All
exponential graphs (of the growth type) look like Js.
In the environmental context, the single most important characteristic of
the exponential function is that as it increases, the absolute amount of
its increase is proportional to the size of the whole at the time, so
that even a small, fixed rate of increase (say 0.5% per year) will result
in huge absolute increases over time. In other words, continuing growth
of any kind is unsustainable in the real world.
2. This is a case of exponential decrease. The appropriate equation is:
C = Co e-at
where C is the pollution concentration in the Lake after t years,
Co is the initial pollution concentration in the Lake,
a is the annual rate of decrease, and
t is the time (elapsed since pollution is stopped) in years.
We first determine a, knowing that C = 0.65Co , and t = 2:
0.65Co = Co e-a(2)
0.65 = e-2a
ln (0.65) = -2a
-0.431 = -2a
or
a = 0.215 (approx.)
Next, we find the value of t that will satisfy the C = 0.25Co requirement:
0.25Co = Co e-(0.215)(t)
0.25 = e-0.215t
ln (0.25) = -0.215t
-1.386 = -0.215t
or
t = 6.4 years (approx.)
Finally, the difference between the two values of t will give the number of
years needed for the pollution level to decrease from 65% to 25% of the
Page 16
initial concentration:
(6.4 - 2) years = 4.4 years.
Chapter 3
3-A
Interrelated Scientific Principles: Matter, Energy, and Environment
TRUE-FALSE QUESTIONS
Where "F" is your answer, change the underlined portion (and the underlined
portion only) of the statement to make it true.
1.In a controlled experiment, the control group and the experimental group
are identical except for the variable under investigation.
2.Repeatability is important to the scientific method because it brings about
more accurate results.
3.Higher chlorine concentrations in drinking water are linked to higher rates
of cancer in the general population. Such a correlation is sufficient
proof in itself that chlorine causes cancer.
4.The chemical behavior of an element is mainly determined by the total
number of protons and neutrons in the nucleus of its atoms.
5. All organic compounds are produced by living things.
6.In photosynthesis, solar energy captured by plants is converted to matter
in the form of organic compounds.
7.Carbon is called the "backbone" of our living environment because carbon is
used by plants produce carbohydrates.
8.Examples of bases include caustic soda and household ammonia.
9.The second law of thermodynamics tells us that energy cannot be recycled.
10.The law of conservation of matter implies that we cannot really throw
things away.
3-B
MATCHING QUESTIONS
Match each of Q.1-7 with the most appropriate item from the following list.
Any item in the list may be used more than once, or not at all.
a. respiration
b. photosynthesis
c. enzymes
d. acid
e. heat energy
of the ocean
f. atomic numbers
g. carbon-12 and carbon-14
h.
base
i. coal
j. Dmitri Mendeleev
1.It is a form of low-quality energy.
2.Carbon dioxide is released in this process.
3.It releases hydrogen ions in a solution.
Page 17
4.It releases hydroxyl ions in a solution.
5.They are catalysts for organic biochemical reactions.
6.Examples of isotopes.
7.Inventor of the Periodic Table.
3-C
MULTIPLE-CHOICE QUESTIONS
1.A substance which alters the rate of a chemical reaction but is not altered
in the process is called
a. an enzyme.
b. a hormone.
c. an
activator.
d. a catalyst.
2.By definition, organic matter is matter that contains
b. carbon.
c. hydrogen.
d. protein.
a. water.
3.Through
living organisms return carbon to the atmosphere.
a. photosynthesis
b. respiration
c. transpiration
d. evaporation
4.Acid rain with a pH of 4 is
a. 2
b. 4
c. 100
d. 1000
times as acidic as rain of pH 6.
5.The first law of thermodynamics states that
a. energy cannot be created
or destroyed.
b. useful energy is lost when energy is converted from
one form to another.
c. the amount of energy in the universe is
decreasing.
d. energy is matter.
6.The matter and energy laws tell us that we can recycle
a. both matter and
energy.
b. neither matter nor energy.
c. matter but not energy.
d.
energy but not matter.
7.Which of the following statements about photosynthesis is true?
a. It
converts glucose into energy and water.
b. It requires carbon dioxide
and nitrogen gas.
c. It yields glucose and oxygen.
d. It involves the
combustion of carbon.
8.Respiration takes place in
a. animals only.
b. plants only.
plants and animals.
d. some plants and all the animals.
9.The pH values of basic solutions lie within the range of
b. 7 - 14.
c. 0 - 7.
d. 1 - 10.
c. both
a. 0 - 14.
10.The second law of thermodynamics is linked to all of the following EXCEPT
a. the energy-matter equivalency.
b. entropy.
c. waste heat.
d. efficiency of energy conversions.
11.By the process of respiration,
is(are) released into the environment,
along with energy for the organism.
a. oxygen
b. carbon dioxide
c. water
d. b and c but not a
Page 18
3-D
QUESTIONS FOR REVIEW, RESEARCH AND CRITICAL THINKING
1. Findings in environmental science are often incomplete, inconclusive, and
open to interpretation and controversy. What are the reasons? Discuss,
using the global warming effect as a case in point.
2. The principle of mass (or materials) balance for a system can be a very
useful tool when applied to estimates of pollutant concentrations in
streams, estuaries or lakes. Outline in your own words the basic ideas
of this principle. Then, express it in the form of a word equation.
Would a similar equation apply to energy balance?
3. The first law of thermodynamics is often loosely stated as the following:
energy cannot be created or destroyed. But what energy are we talking
about here? How could we reconcile the first law with the second law,
which states that energy conversions always result in the loss of useful
energy?
4. What basic information on the chemical elements can one obtain from
reference to a Periodic Table?
5. What is the difference in meaning between cycles and flows? People
normally speak of energy flows and material cycles, but can you think of
situations where one would be justified to speak of energy cycles and
material flows? Elaborate.
6. (a) Write a word equation each for photosynthesis and respiration.
(b)Explain how through photosynthesis and respiration, animals and plants
become interrelated to and interdependent on each other.
7. According to Table 3.1, what is the percent efficiency of an automobile
engine? Of an incandescent lamp? What are the environmental
implications of such low efficiencies?
8. (a)How does a total energy analysis differ from a partial energy analysis?
(b)Consider as an example the generation of electricity by nuclear power.
What would a total energy analysis involve?
9. (a)Field samples are a major source of environmental data. When
collecting them, what requisites of proper sampling must one follow
to ensure reasonable representativeness of the samples?
(b)In the 1936 US presidential election, the Literary Digest predicted
with confidence that Alfred M. Landon would be the winner, based on
responses from long lists of car owners, telephone subscribers and
its own subscribers. As it turned out, Franklin D. Roosevelt won,
and by a wide margin. What do you think went wrong with the
sampling method?
3-E
WORKING WITH NUMBERS AND GRAPHS
1. A coal-fired electric power plant has an efficiency of 35%. River water is
used for removing 80% of the waste heat (the other 20% goes up the
Page 19
smokestack). If the power plant output is 400 MW (megawatts), how much
waste heat is being discharged into the river every second?
2. The efficiency E, in %, of a certain gasoline engine is given by
E = 100 (1 - r-0.3), where r is the compression ratio. What is the
efficiency when r = 9?
3. What physical conditions do pH values indicate? Rain in southern Ontario
has been observed to have pH values close to 4.3. How many times is this
rain as acidic as "normal" rain of pH 5.5?
4. Refer to the diagram of the Periodic Table in your text. Consider the
element Cl (chlorine; Atomic Number 17):
a) How many electrons does an atom of this element have in its outermost
electron shell?
b) How many electrons in total does an atom of this element have?
c) Would you expect this element to be chemically active? Why or why not?
Page 20
Chapter 3
Answers and Solutions
3-A
T: Q.1, 8, 9, 10
F: Q.2, 3, 4, 5, 6, 7
Q.2
it helps to confirm the quality of the data
Q.3
not sufficient proof in itself that chlorine causes cancer
Q.4
determined by the number of electrons in the outermost electron
shell
Q.5
Not all
Q.6
chemical energy of the glucose synthesized by the plants
Q.7
the basic element in all living matter
3-B
1e
2a
3d
4h
5c
6g
7j
3-C
1d
2b
3b
4c
5a
6c
7c
8c
9b
10a
11d
3-D
1. A number of reasons could be given, e.g.
a. Systems and processes under study are very complex and involve time
scales of decades or even centuries. Data is often inadequate.
b. The many and varied factors cannot be studied under control conditions
in the real world. Unequivocal cause-effect evidence is virtually
impossible to obtain.
c. Even when there is sufficient data available, different groups could
come up with very different interpretations and conclusions, owing to
the value-dependent nature of environmental science itself.
In the case of global warming, even though most scientists have now
concluded that the earth is heating up and the most probable cause of it
is the combustion of fossil fuels, there are still skeptics who dispute
the evidence or at least do not think the evidence is strong enough.
There is even less consensus among scientists on issues like the speed of
progression, the magnitude, and the future consequences of the effect.
2. For a given system (e.g. a lake) over a given period of time (e.g. three
months), the mass of a given substance (e.g. suspended solids) entering
the system must be equal to the mass of the substance leaving the system,
plus or minus the change in the mass of that substance in the system.
Thus, over any period of time,
Mass in = Mass out + Change in mass in system
Yes, a similar equation (energy balance equation) can be written for
energy.
3. It's the total amount of energy we're talking about here. Thus, while
electrical energy may be "lost" when it is converted to sound, the sum
total of all forms of energy at the beginning of a process must be equal
to the sum total of all forms of energy at the end of a process. There
is no contradiction, of course, between the first law and the second law
because the first law concerns itself with total energy, while the second
law with higher-quality energy.
Page 21
4. Chemical symbol, atomic number, atomic weight, number of electrons in the
outermost electron shell (which may be used as a clue to the general
chemical behavior of the element).
5. "Cycle" conveys the notion of something moving around indefinitely undiminished and unaltered, whereas "flow" suggests an irreversible or
unidirectional movement. We could speak of material flows in the right
circumstances (e.g. inflow into and outflow from a lake), but to speak of
"energy cycles" would be contradicting the second law of thermodynamics.
6. (a)Photosynthesis: Carbon dioxide + Water + Sunlight = Glucose + Oxygen
Respiration:
Glucose + Oxygen = Carbon dioxide + Water + Energy
(b)Plants supply the food and the oxygen that animals need. Animals in
turn give plants the needed carbon dioxide.
7. Automobile engine: 25% efficiency (This figure should be higher now.)
Incandescent lamp: 4% efficiency
Environmental implications:
(i)Huge energy savings could be realized through improvements in machine
efficiencies;
(ii) Lower energy consumptions need not mean "lower" living standard, but
simply switching from energy-inefficient machines to energyefficient ones.
8. (a)A total energy analysis takes into account energy expended in every
part of the process, whereas a partial energy analysis doesn't.
(b)The energies expended on extracting the uranium, refining it,
transporting it; on building, operating and finally decommissioning
the nuclear power plant; on storing the radioactive waste; on
producing and deploying whatever materials that are used in the
power plant...The sum of all those energies is then compared with
the total amount of electrical energy delivered during the life of
the nuclear power plant.
9. (a)Samples should be random, sufficiently large (in size) and broad
(across the entire spectrum of the population).
(b)Though large in size, the sample was biased, being made up of the more
affluent Americans.
3-E
1. Power input to plant = Power output from plant + Waste heat discharge
(100%)
(35%)
(65%)
Since 35% of the power input = 400 MW
100% of the power input = 400 x (100/35) MW = 1140 MW (approx.)
65% of the power input (i.e. the waste heat discharge) = 1140 x 0.65 MW
= 740 MW (approx.)
As 80% of the total waste heat discharge goes into the river,
it amounts to 740 MW x 0.8 = 590 MW of waste heat into the receiving water.
Therefore, waste heat is being discharged into the river at a rate of 590
million joules per second.
2. E = 100 (1 - r-0.3) = 100 (1 - 1/9-0.3) = 100 (1 - 0.517) = 48% (approx.)
Page 22
3. Values of pH are used to indicate the relative acidity or alkalinity of
solutions. The pH scale is logarithmic. A difference of 1.2 on the pH
scale means that the acidity of acid rain is about 16 (i.e., 101.2) times
that of "normal" rain.
4. a) 7
b) 17
c) Yes, chemically active. Chlorine atoms tend to bond with atoms of other
elements in such a way as to increase the number of electrons in their
outermost shells to eight.
Page 23
Chapter 4
4-A
Interactions: Environment and Organisms
TRUE-FALSE QUESTIONS
Where "F" is your answer, change the underlined portion (and the underlined
portion only) of the statement to make it true.
1.Ecology is basically the study of plants and animals.
2. Temperature, pH and bacteria are all abiotic factors.
3.A population is a group of organisms of different species living together
in an area.
4.Even for the same species in the same area, the limiting factor may change
if the environmental conditions change.
5. Intraspecific interactions are those that occur within the same species.
6. Material cycles include the carbon-oxygen cycle, the nitrogen cycle, and
the hydrologic cycle.
7.Fossil fuel combustion and deforestation are significantly disrupting the
carbon-oxygen cycle on a global scale.
8.The role of decomposers is to consume food.
9.In aquatic habitats, the higher the water temperature is, the lower the
solubility of oxygen in the water is.
10.When several food webs overlap and intersect, they make up a food chain.
11.The phosphorus cycle differs from the nitrogen cycle or the carbon-oxygen
cycle in that the phosphorus cycle does not have a major gaseous phase,
and its cycling time is extremely long.
4-B
MATCHING QUESTIONS
Match each of Q.1-7 with the most appropriate item from the following list.
Any item in the list may be used more than once, or not at all.
a. predation
b. symbiotic relationships
c. commensalism and mutualism
d. mutualism
e. commensalism
f. parasitism
g. intraspecific
competition
h. interspecific competition
1.Orchids growing on the surface of a tree.
2.Fleas living in the feathers of a bird.
3.Nitrogen-fixing bacteria living in the roots of pea plants.
4.Several vultures competing for a food source.
Page 24
5.Effect is positive on one interacting species, and neutral on the other.
6.Participating species may benefit from, or be harmed by, or be unaffected
by the interactions.
7.Predator-prey relationships.
4-C
MULTIPLE-CHOICE QUESTIONS
1.Which of the following is NOT a symbiotic relationship?
a. parasitism
b. mutualism
c. commensalism
d. competition
2.Interacting groups of different species of organisms are called
a. communities.
b. ecosystems.
c. populations.
d. biomes.
3.Which of the following would be considered a primary consumer?
a. A human.
b. A frog.
c. A rabbit.
d. A lion.
4.Energy
a. flows in only one direction.
b. recycles through the
ecosystem.
c. is used over and over again.
d. resides in living
organisms only.
5.The shorter the food chain, the
a. smaller the loss of usable energy.
b. fewer the number of organisms supported.
c. greater the heat loss.
d. slower the rate of photosynthesis.
6.When garter snakes feed on frogs that feed on spiders that feed on insects
that feed on willow leaves, the tertiary consumers are the
a. garter snakes.
b. frogs.
c. spiders.
d. insects.
7.Nitrogen gas in the atmosphere is converted into a form usable by the
plants by
a. denitrifying bacteria.
b. nitrifying bacteria.
c. nitrogen-fixing bacteria
d. all of the above.
8.An organism's niche is analogous to its
a. territory.
life cycle.
d. predator-prey relationships.
b. role.
c.
9.All of the following groups are consumers EXCEPT
a. scavengers.
b. decomposers.
c. carnivores.
d. herbivores.
10.Highly oxygenated stream waters (such as those required for trout spawning)
typically have dissolved oxygen levels of at least
a. 5 ppm.
b. 8
ppm.
c. 15 ppm.
d. 2 ppm.
4-D
QUESTIONS FOR REVIEW, RESEARCH AND CRITICAL THINKING
1. (a)What is ecology concerned with? How does it differ from botany or
zoology?
(b)Why is environmental science often closely associated with ecology?
2. For a given species in a given area, is the limiting factor always the
Page 25
same?
Explain.
3. List three ecological concepts or principles you consider fundamental to
environmental studies. Explain why each is important, and suggest what
we can learn from each in the realm of environmental management.
4. (a)State the 10% rule (as it relates to food pyramids) as clearly as you
can in terms of biomass at different trophic levels. Is the 10%
figure a precise one? What happens to the other 90%?
(b)Suppose in a pond there is a total of 8000 kg of plant matter.
Estimate the total amount of biomass at each of the next two higher
trophic levels in the pond.
5. (a)Was it need (the need to become dark-colored so as to survive in the
new environment) that caused the peppered moths to gradually change
from light color to dark color in industrial regions of England
during the 19th century? Amplify.
(b)If organisms can and do adapt to changes in the environment, why should
humans worry about pollution?
6. Distinguish between interspecific relationships and intraspecific
relationships. Give three examples of interspecific relationships, and
three examples of intraspecific relationships.
7. What on-going human activities, on either a local scale or a global scale,
are significantly disrupting (a) the carbon-oxygen cycle, (b) the
nitrogen cycle, (c) the phosphorus cycle, and (d) the hydrologic cycle?
8. Contrast an urban system (e.g. Toronto) with a natural ecosystem (e.g. Lake
Ontario) with respect to (a) energy supply and consumption;
(b)
materials supply; (c) waste generation and disposal; (d) population
growths and control mechanisms.
What are the basic differences between the two systems? What are the
environmental implications for humans?
9. Environmental science reporting by the media is not without its fair share
of hyperbole, "red herrings" and dubious interpretations. Suppose you
are confronted with an article on a complex environmental issue, tell
what general steps you would follow to determine whether
(a) you understand the article properly;
(b) the information presented is factual;
(c) the reasoning and the analysis are sound; and
(d) the conclusion arrived at is justified.
10.
In one 1990 article, the executive vice president of British Petroleum
(America) tells us that carbon monoxide emissions from automobiles have
been slashed by over 95%. In another 1990 article, a senior researcher
in Washington, D.C. states that carbon monoxide emissions from cars have
been reduced by an average of 85%. The discrepancy between the two given
figures, though not huge, is nonetheless significant (10% or higher).
Suggest some plausible reasons for the difference, assuming that both
figures are derived from the same set of data.
Page 26
4-E
WORKING WITH NUMBERS AND GRAPHS
1. A chemical spill occurs in a stream. If, with mixing, the concentration of
the pollutant decreases 5% for each kilometer downstream, how far
downstream from the spill will the pollutant concentration be reduced to
50% of its initial reading?
2. Water temperature as observed at a station in the upper section of a river
is 8.5o C. If water temperature increases 12% for each 40 km downstream,
how far downstream from the station will water temperature be 20o C?
3. Effluent from a food processing plant is discharged into a river. The BOD
of the effluent is 80 mg/L. The receiving river has a BOD of 2 mg/L, and
a streamflow of 60 million liters per day. If, immediately after mixing,
the BOD of the river water is not to exceed 5 mg/L, what will be the
maximum allowable amount of effluent discharge from the plant?
Page 27
Chapter 4
Answers and Solutions
4-A
T: Q.4, 5, 6, 7, 9, 11
F: Q.1, 2, 3, 8, 10
Q.1
interactions of organisms with one another and with their
nonliving environment
Q.2
Temperature, pH and humidity
Q.3
organisms of the same species
Q.8
break down matter
Q.10 food chains; food web
4-B
1e
2f
3d
4g
5e
6b
7a
4-C
1d
2a
3c
4a
5a
6b
7c
8b
9b
10b
4-D
1. (a)Ecology is concerned with interactions. Botany is the study of plants.
Zoology is the study of animals. Ecology is the study of
interactions among organisms, and interactions between organisms and
their nonliving environment.
(b)The earth is just one large ecosystem made up of many smaller ones.
Much of the workings of the earth's ecosystems can be understood
from the laws, principles and concepts of ecology.
2. No. The limiting factor changes with the environmental conditions. For
example, water is often the limiting factor for plants on land, but if
the soil has a lot of water, the limiting factor for plants may change to
something else.
3. Three such principles could be
(a)All components of an ecosystem are interdependent and interrelated.
Importance: It demonstrates to us the workings of ecosystems.
Message: No organism lives and functions in isolation. Humans are part
of nature and must manage the earth with this in mind.
(b)All materials in ecosystems are reused and recycled.
Importance: It explains why in ecosystems there is no depletion of raw
materials and no buildup of wastes.
Message: Humans should reduce, reuse and recycle as much as they can.
(c)All energy is supplied by the sun.
Importance: It explains why ecosystems do not run out of energy and
do not suffer from air pollution.
Message: We should reduce our fossil fuel consumption, and more of our
energy supply should come from renewable energy sources.
4. (a)The biomass that can be sustained at a given trophic level is
approximately 10% of that at the next lower level.
No, the 10% figure is only an approximate one. The other 90% of the
mass is either not utilized (biodegradation) or is used as energy to
support the life activities of organisms at the higher level.
(b)800 kg and 80 kg respectively.
Page 28
5. (a)No, it was not caused by need - whether there was need or not, some of
the moths would have been born dark-colored anyway. It was the
changes in the environment that allowed the dark-colored moths to
multiply.
(b)First there is no guarantee that adaptation would occur - it depends on
the nature and degree of the pollution. Second, adaptation takes a
long time, and in that time span, humans pay the price.
6. Interspecific: Between different species. Examples: Competition for food
between two species of animals; predator-prey
relationship between two species of animals; parasitehost relationship between two species of organisms
Intraspecific: Within the same species. Examples: Competition,
cooperation, mating
7. (a)Carbon-oxygen cycle: Deforestation; fossil fuel combustion
(b)Nitrogen cycle: Chemical fertilizer use; livestock waste disposal; poor
farming practices that impoverish soils
(c)Phosphorus cycle: Municipal sewage effluent; chemical fertilizer use
(d)Hydrologic cycle: Mismanagement of watersheds; urban land uses; dams,
reservoirs and water diversion projects
8. The basic differences are that Lake Ontario is self-sufficient in materials
and energy, is self-regulating with regard to population sizes, and has
no buildup of wastes, which is not true of Toronto. The implications are
Toronto is unsustainable on a longer-term basis.
9. (a)Try to explain the main points of the article to someone without the
use of jargon; try to summarize the article in one or two sentences;
ask yourself if you clearly understand all the assumptions, terms,
analysis and arguments in the article.
(b)Find out how the information was obtained in the first place. Check
out all the data given; compare it with other sources of data.
(c)Be skeptical and challenge every step of the reasoning; subject all
claims to scrutiny.
(d)Be wary of sweeping statements and oversimplifications, extrapolations
or selective use of data, and unwarranted cause-and-effect
conclusions.
10.
The BP executive was probably referring to peak efficiencies when catalytic
converters are new and operating under optimal conditions (e.g. when the
engine has properly warmed up). The researcher, on the other hand, was
probably talking about average efficiencies of cars on the road. Each
may have had self-serving reasons to selectively use the available data
and thereby arrive at a conclusion he or she would like to have.
4-E
1. We'll use the compound
C =
where C represents the
Co represents the
interest formula to calculate the decrease:
Co (1 - 0.05)n
50% concentration downstream,
initial (maximum) concentration, and
Page 29
n represents the required number of kilometers downstream to
achieve the 50% reduction.
Rewriting C as 0.5Co , we have:
0.5Co = Co (0.95)n ,
or
0.5 = (0.95)n ,
log 0.5 = n log 0.95
-0.30 = -0.022n
n = 14 (km) approximately.
2. We'll again use the compound interest formula:
20 = 8.5 (1 + 0.12)n
2.35 = (1.12)n
n = 7.55 (approx.)
But in this case, we have to multiply n by 40 km to get the required
distance downstream, therefore
n x 40 km = 7.55 x 40 km = 300 km (approx.)
3. Assume that the streamflow does not vary appreciably from hour to hour.
Then
(80 mg/L) x D + (2 mg/L) x (60 x 106 L/day)
= (5 mg/L) x (60 x 106 L/day + D)
where D is the maximum allowable amount of effluent discharge per day.
Solving the equation for D, one has
75 D = 180 x 106 L/day, or
D = 2.4 x 106 L/day (approx.)
Page 30
Chapter 5
5-A
Ecosystems and Communities
TRUE-FALSE QUESTIONS
Where "F" is your answer, change the underlined portion (and the underlined
portion only) of the statement to make it true.
1. Succession refers to the gradual, sequential and often predictable change
in the structure of a community in space and time.
2.As succession progresses, each of its stages, except the climax, is
replaced by the next.
3. Secondary succession occurs when an existing community is destroyed in some
way, for example by a forest fire.
4.Succession that occurs on a sand dune and succession that occurs on bare
rock are examples of primary succession.
5.Terrestrial biomes are major geographic zones each of which is
characterized by its own climax community.
6.Prairies are found in areas that generally receive between 25 and 75 inches
of precipitation per year.
7.In a tropical rain forest, the bulk of plant nutrients come from the
fertile tropical soil.
8.Despite the substantial amount of snowfall, winter remains relatively dry
for trees in the boreal forest.
9.A change in altitude can affect climate in the same way as a change in
longitude.
10.Organisms that live on the ocean bottom are called pelagic, and those that
live in the water are called benthic.
11.The euphotic zone is the uppermost layer of the ocean where there is
sufficient sunlight for photosynthesis.
12.Relative to Lake Superior, Lake Erie and Lake Ontario are oligotrophic
lakes.
5-B
MATCHING QUESTIONS
Match each of Q.1-7 with the most appropriate item from the following list.
Any item in the list may be used more than once, or not at all.
a. coral reef ecosystem
b. lichens
c. benthic organisms
d. Arctic
tundra
e. tropical rain forest
f. sere
g. climax community
h. estuary ecosystem
i. BOD
1.Characterized by a higher degree of complexity and stability than any of
Page 31
the earlier communities.
2.This biome typically has waterlogged soils during the summer.
3.Infertile laterite soil is common in this biome.
4.Plants like kelp and crustaceans like crabs are examples.
5.They play the role of a pioneer species.
6.Its water exhibits large diurnal fluctuations in salinity.
7.Its animals carry symbiotic algae in their cells.
5-C
MULTIPLE-CHOICE QUESTIONS
1.The biome typical of most of the eastern half of the United States and
parts of southeastern Canada is the
a. boreal forest.
b. temperate
deciduous forest.
c. temperate rain forest.
d. taiga.
2.Going north from southern Alberta, the biome you would expect to find after
the prairie is the
a. tundra.
b. savanna.
c. boreal forest.
d.
temperate deciduous forest.
3.The two most important factors that determine the kind of (terrestrial)
biome in a region are
a. sunlight and soil type.
b. wind speed and
moisture.
c. latitude and temperature.
d. temperature and
precipitation.
4.Which of the following pairs of factors generally has the greatest impact
on the phytoplankton productivity of a marine ecosystem?
a. Water
temperature and precipitation.
b. Nutrient concentration (in the
water) and sunlight.
c. Salinity and temperature of the water.
d. Latitude and ocean current.
5.Which of the following trees would you associate with Canada's temperate
rain forest?
a. Red cedar and Douglas fir.
b. Eastern hemlock and
black spruce.
c. Sugar maple and beech.
d. Black spruce and white
spruce.
6.Succession occurs primarily because of
a. drought. b. forest fires.
c.
mutation.
d. change in the environment caused by the living organisms.
7.Which of the following statements about a climax community is NOT true?
a. It tends to accumulate large amounts of new material over time.
b. It is essentially in energy balance.
c. It is essentially in
material balance.
d. It tends to last longer than any other
successional community.
8.A pioneer community
a. tends to accumulate new material over time.
b. lasts longer than any other successional community.
c. consists of
the initial species that colonize an ecosystem.
d. a and c but not b.
Page 32
9.Most attempts to farm large areas of tropical rain forests on a long-term
basis have resulted in failures on account of
a. the myriads of bugs
and insects that infest the crops.
b. the infertile soil and its
tendency to become hard.
c. the high rates of evaporation from the
soil.
d. the high costs of chemical fertilizers and pesticides.
10.Lakes that are
tend to be biologically more productive.
a. large and deep
b. high in dissolved oxygen
c. relatively shallow
d. low in nitrates and phosphates
5-D
QUESTIONS FOR REVIEW, RESEARCH AND CRITICAL THINKING
1. The broadly defined life zones of southern Canada include the Atlantic
Maritime, the Boreal, the Great Lakes/St. Lawrence, the Pacific/Mountain
and the Prairie Life Zones. Rearrange these zones in a west-east
sequence and identify the province(s) that comprise(s) each of them.
2. Inasmuch as the modus operandi within and between ecosystems is
interdependence and interconnectedness, what purpose does it serve to
divide the earth's surface into biomes?
3. What would you suggest as the first principles of biome management?
4. How would you explain to someone who has difficulty understanding why, once
clear-cut, virgin forests are unlikely to ever grow back to the original
ecological state again?
5. Give the general relationship between biodiversity and climate.
the reasons for this relationship?
What are
6. At one time, large herds of bison, antelope and deer were present on the
North American prairies; today they have been largely replaced by
domestic cattle.
(a)What damaging effects, if any, might the bison, antelope and deer have
had on the prairie ecosystem (e.g. on the grass, soil and other
forms of wildlife)?
(b)In what ways are the ecological effects of today's domestic herds
different? Discuss.
7. Why is it that the use of fresh water for irrigation often leads to
salinization of soil? Where is the salt coming from? And what kind of
salt are we talking about here?
8. One of the most amazing facts about the productivity of marine ecosystems
is that almost 50% of the total marine fish production comes from only
0.1% of the ocean area, and another 50% of the fish production from 10%
of the ocean area (with the rest of the ocean being virtually a
biological desert). Why is there so much spatial variability in marine
fish production? Is this variability entirely due to variability in
phytoplankton (primary) production? Why don't we see terrestrial
parallels of this phenomenon?
Page 33
9. In light of the fact that almost half of Canada's land area is covered by
forests, do you think that public concern over logging, and opening more
forests to logging, is warranted? Discuss.
5-E
WORKING WITH NUMBERS AND GRAPHS
1. Refer to the climatograph for Moscow (Fig. 5.14a) in your text.
(a)What is Moscow's annual temperature range, in o C?
(b)What is Moscow's annual precipitation, in cm?
(c)What is Moscow's mean temperature, in o C, in July?
(d)If you were to spend ten days in Moscow next July, how many of those
ten days would you expect, on a statistical basis, to be days with
precipitation?
2. From a comparative study of Fig. 5.8 (Influence of Precipitation and
Temperature on Vegetation) and Fig. 5.16 (Relationship between Altitude,
Latitude, and Vegetation), deduce an approximate quantitative
relationship for the variation of temperature with altitude.
Page 34
Chapter 5
Answers and Solutions
5-A
T: Q.2, 3, 4, 5, 8, 11
F: Q.1, 6, 7, 9, 10, 12
Q.1
over time
Q.6
between 25 and 75 cm
Q.7
the plants and animals that die
Q.9
latitude
Q.10 benthic; pelagic
Q.12 eutrophic
5-B
1g
2d
3e
4c
5b
6h
7a
5-C
1b
2c
3d
4b
5a
6d
7a
8d
9b
10c
5-D
1. From west to east: the Pacific/Mountain (British Columbia and part of
Alberta), the Prairie (Alberta, Saskatchewan and part of Manitoba), the
Boreal (part of Manitoba, Ontario and Quebec), the Great Lakes/
St. Lawrence (Ontario and Quebec), and the Atlantic Maritime (New
Brunswick, Prince Edward Island and Nova Scotia).
2. The principles of interdependence and interconnectedness do not preclude
the concept of biomes. It is often convenient and instructive to study
these broadly defined ecosystems as entities because each biome does have
its own ecological characteristics and specific environmental problems.
3. Recognize the conditions, processes and limits of your biome and manage it
in a sustainable manner. Work with nature rather than attempting to
"conquer" it. It doesn't make ecologic (or economic) sense, for example,
to try to grow wheat in the tundra or vegetables in a semi-desert. As
one ecologist aptly put it: "Man proposes and nature disposes."
4. Aside from the wholesale alteration of the environment immediately
following the clearcutting, there are other long-term, often
irreversible, changes in the forest ecosystem. Factors like replanting
with single-species trees, loss of much of the original biotic community,
continuing human disturbance and intervention, topsoil loss and so on
will work against the forest ecosystem ever returning to its original
state. If allowed to develop by humans, a forest will eventually grow
back, but it will be a different kind of forest - most probably one with
lower biodiversity.
5. Biodiversity, in terms of both species diversity and genetic diversity,
increases with temperature and rainfall. The main reason is that higher
temperature and rainfall promote plant growth both horizontally and
vertically, resulting in not only more food for animals but also more
microenvironments for plants and animals. This in turn translates into
higher biodiversity.
Page 35
6. (a)While the wild herds were grazing on a particular area, the stress on
that area was probably high but temporary. As the herds moved on,
the grass was able to recover, and no permanent damage was done.
The other grazing animals that were competing for food with the
bison, antelope and deer might have been put under some pressure,
but if the carrying capacity of the land was not exceeded, survival
of the other grazers would not have been a problem either.
(b)The domestic cattle, in contrast, are usually kept on the same tracts
of land and overgrazing occurs. The grass is damaged beyond
recovery, and soil degradation (erosion/compaction) follows. The
land then becomes unproductive. Wildlife also suffers as the
predator species are hunted down and grazing animals are fenced off
(often leading to their starvation and death in the winter).
7. Salinization is the accumulation of salt in the soil. The salt could come
from the surface water used for irrigation (fresh water of course is not
totally devoid of salt); from the groundwater (which usually has a higher
salt content and which has now risen as a result of irrigation or the
removal of deep-rooted plants); and/or from the soil itself. The salts
referred to are chemical salts, mostly those of calcium, magnesium,
sodium and potassium.
8. Two different factors are involved here: one is marine phytoplankton
abundance, the other is the number of trophic levels in the food pyramid.
Phytoplankton productivity is low in most parts of the ocean on account
of a lack of plant nutrients, but in upwelling areas (where rising water
brings up nutrients from the bottom) phytoplankton are several times more
abundant than average. More importantly, in such upwelling areas, some
fish species feed near the bottom of the food pyramid, thus reducing the
number of trophic levels involved from, say, five to three. A 2-level
reduction in the food pyramid is tantamount to something like a 100-fold
increase in the amount of available food. Together then, these two
factors are responsible for the several hundred-fold increase in fish
production that occurs in upwelling areas.
We don't see terrestrial parallels of this partly because of human
intervention (in their efforts to farm the land), and partly because
humans mostly go to the base of the pyramid for food supply.
9. We could debate this issue from the ecological, cultural or ethical
perspective, but let's use the following table as a guide and see if we
could settle things on a costs-vs-benefits basis. After the dollar
amounts have been entered (using available statistics or guesstimates),
we can then compare the bottom-line figures. Most would probably come to
the conclusion that costs exceed benefits here.
Relevant questions to ask in this exercise include: Who's benefiting from,
and who's paying for, logging? How do we balance long-term interests
against near-term needs? How important are the interests of one
particular group as opposed to those of society at large?
As for the perception that Canada's forestry resources are vast, it's a bit
of a myth. First, many forested areas are not easily accessible.
Second, logging as it is practiced in Canada today is unsustainable.
Page 36
People/Ecosystem Affected
Costs of Logging
Loggers
Near-term:
Longer-term
Forestry Companies
Governments and Society
at large
Forest Ecosystems
Benefits of Logging
$
$
?
?
Near-term: Jobs
Longer-term:
$
$
?
Near-term: Royalties and
reforestation costs
$
Longer-term:
$
?
Near-term: Profits
Near-term: Remedial
programs to control soil
erosion, water pollution,
siltation in waterways,
floods and droughts
$
Loss of jobs in tourism
industry of the area
$
Loss of cultural heritage
and biodiversity $
?
Longer-term:
Similar to near-term
costs above
$
?
$
?
$
?
Near-term: Revenues for
governments and jobs for
some communities
$
Longer-term:
$
?
Near-term: Loss of
natural habitats and
biodiversity
$
Longer-term: Loss of
biodiversity
$
Near-term:
$
?
Longer-term:
$
?
All of above
$
Longer-term:
$
?
?
$
$
5-E
1. (a)38 Celsius degrees (from -12o C to 26o C).
(b)About 55 cm. (2.7 + 2.5 + 2.8 + ... + 4.0)
(c)19.5o C.
(d)About 4 (10 x 0.39) days.
2. For the deciduous forest:
From Fig. 5.16, the difference in altitude is (3600 - 1800) m,
or 1800 m.
From Fig. 5.8, the temperature difference is (2 - 17)o C, or -15o C.
Therefore, the variation of air temperature with altitude is
(-15o C/1800 m) x 1000 = -8o C/1000 m of ascent
For the tundra:
From Fig. 5.16, the difference in altitude is 500m.
Page 37
?
From Fig. 5.8, the temperature difference is -6o C.
Therefore, the variation of air temperature with altitude is
(-6o C/500 m) x 1000 = -12o C/1000 m of ascent
Chapter 6
6-A
Population Principles
TRUE-FALSE QUESTIONS
Where "F" is your answer, change the underlined portion (and the underlined
portion only) of the statement to make it true.
1.Most estimates have placed the 1996 world population within the range of
5.8 to 6.0 billion.
2.In humans, about 102 males are born for every 100 females.
3.The birthrate refers to the annual number of live births per 1000 women in
the population.
4.In Canada, by the time people reach their mid-twenties, a higher death rate
for males has equalized the sex ratio.
5.A population typically grows very slowly in the stable equilibrium phase
because the process of reproduction and growth of offspring takes time.
6.Environmental resistance includes such factors as the lack of food or the
decreasing oxygen supply.
7. Density-dependent factors are those limiting factors that become more
severe as the size of the population increases.
8.The environmental factors that limit population sizes are known
collectively as the carrying capacity.
9.The prereproductive component in a population refers to those members who
are 0 - 16 years of age.
10.In general, the age distribution of a developed country would have a shape
different from that of a developing country.
6-B
MATCHING QUESTIONS
Match each of Q.1-7 with the most appropriate item from the following list.
Any item in the list may be used more than once, or not at all.
a. available food and space
b. net migration
c. rule of 70
d. an
invading species
e. volcanic eruptions and floods
f. U.S. population
growth
g. age distribution
h. Denmark's population growth
1.Zebra mussels in the Great Lakes.
2.It is characterized by very nearly zero growth.
3.Another name for population age structure.
Page 38
4.Examples of density-dependent factors.
5.Examples of density-independent factors.
6.The difference between the number of immigrants and the number of
emigrants.
7.Useful for estimating the doubling times for steady compound growths.
6-C
MULTIPLE-CHOICE QUESTIONS
1.Organisms known as r-strategists typically have
a. high birthrates.
b. high deathrates.
c. fairly constant populations.
d. high
birthrates as well as high deathrates.
2.For most countries of the world, the factor that most affects their yearover-year changes in total population is the
a. birthrate.
b. natural
growth rate.
c. net migration rate.
d. deathrate.
3.The world's population (circa 1996) is growing at an annual rate of about
a. 0.9%.
b. 1.2%.
c. 1.5%.
d. 2.0%.
4.A population with a low birthrate (and no net migration) will
a. decline in size.
b. grow if it has a lower deathrate.
c. grow
slowly.
d. also have a high deathrate.
5.K-strategists typically have
a. high birthrates.
b. high deathrates.
c. fairly constant populations.
d. high birthrates as well as high
deathrates.
6.At a 1.4% annual growth rate, a population would double in size in about
years.
a. 40
b. 50
c. 60
d. 71
7.The carrying capacity of an ecosystem is
a. its environmental resistance.
b. its biotic potential.
c. the maximum number of organisms it can
support under normal conditions.
d. the minimum number of organisms it
can support under the harshest conditions.
8.How many individuals are being added to a country's population annually
depends on
a. the present size of the population.
b. the annual
growth rate.
c. the net annual migration rate.
d. both a and b.
9.Which of the following is NOT a major factor in determining the carrying
capacity of an area?
a. Birthrate of the population.
b. Available
energy. c. Available raw materials.
d. Waste buildup.
10.The world population was growing most rapidly (in annual percentage terms)
during the
a. 1940s.
b. 1960s.
c.1980s.
d. early 1990s.
6-D
QUESTIONS FOR REVIEW, RESEARCH AND CRITICAL THINKING
Page 39
1. Compare Fig. 6.5 and Fig. 6.9. What approximate period in human history
might be considered the equivalent of (a) the lag phase, (b) the
exponential growth phase, and (c) the equilibrium phase?
2. Give two examples of r-strategists.
Give two examples of K-strategists.
What does the letter r allude to?
What does the letter K allude to?
3. Describe the demographic characteristics of the Canadian population in the
mid-1990s.
4. "All methods of population projections are inherently inaccurate, but
projections based on age distributions are perhaps somewhat more reliable
than those based on mathematical equations or models." Do you concur
with the above statement? Why or why not?
6-E
WORKING WITH NUMBERS AND GRAPHS
1. (a)Express the growth rate of a population mathematically by an equation,
taking into account the birthrate, the deathrate, the immigration
rate and the emigration rate. Define all symbols used, and give
their units where necessary.
(b)Why are birthrates and deathrates often given as the number of births
or deaths per thousand (rather than per hundred) individuals of the
population?
(c)Find Canada's birthrate and deathrate in 1993, given the following
data:
Births in 1995 = 383,000;
Deaths in 1995 = 213,000;
Mid-1995 population = 29,600,000
2. Refer to Fig. 6.1 in the text.
(a)From the given data, find Costa Rica's population growth rate, in %,
for Year 1. Repeat for Years 2 through 5.
(b)How were the various population sizes (1023, 1047...) shown in the
diagram arrived at? In particular, explain why for the US and
Hungary you are able to find the population sizes by simply adding a
constant to the previous year's figure (for example, in the case of
the US, add 7 to year 2 to get year 3), but the same method would
not work for Costa Rica.
(c)As an application, use the Costa Rica graph to determine its population
at the beginning of Year 5, if at the beginning of Year 1, Costa
Rica's population is 2,850,000.
3. (a)How would you describe the general shape of each of the three age
distributions as shown in Fig. 6.3? What information from the age
distributions allows you to predict that i) Kenya's population is
likely to grow rapidly, ii) the US population is likely to grow
slowly, and iii) Denmark's population is likely to remain constant
or decline marginally? Do age distributions provide all the
necessary information for making population projections? Elaborate.
(b)What other general information can you derive from age distributions?
Page 40
What use can you make of the information obtained thereof?
4. Referring again to Fig. 6.3, and assuming no change in the growth trend,
show graphically and qualitatively the Kenya age distribution 15 years
from the time the one in Fig. 6.3 was constructed. For comparison,
superimpose the new age distribution on the old one.
5. (a)Write the rule of 70 (or rule of 72) in equation form. Define all
symbols used and give their units where necessary.
(b)What can you use the rule of 70 for? What limitations of the rule
should you be aware of?
(c)Use the rule of 70 to find the doubling times corresponding to the
rates of annual increase in % ( 4.0%, 3.5%, 3.0%...) shown in
Fig. 6.10. How good is the agreement between the doubling times given
in the book and those obtained by you?
(d)As a second application of the rule of 70, use it to find the missing
quantities in the table below:
Year
1800
?
1975
?
World Population
Annual Growth Rate
Doubling Time
1000 million
} ------------ ?% ------------- 130 years
2000 million
} ------------ ?% ------------? years
4000 million
} ----------- 1.6%------------? years
8000 million
Page 41
Chapter 6
Answers and Solutions
6-A
T: Q.1, 4, 6, 7, 10
F: Q.2, 3, 5, 8, 9
Q.2
106 males are born for every 100 females
Q.3
per 1000 members
Q.5
in the lag phase
Q.8
the environmental resistance
Q.9
0-14 years of age
6-B
1d
2h
3g
4a
5e
6b
7c
6-C
1d
2b
3c
4b
5c
6b
7c
8d
9a
10b
6-D
1. Lag phase: Prehistoric times -> 1600
Exponential growth phase: 1600 -> 2100 (perhaps)
Equilibrium phase: 2100 on
2. - Grasshoppers, oysters. "r" alludes to the growth rate (r).
- Humans, elephants. "K" alludes to a numerical constant that is
introduced in modeling a population in transition, from exponential
growth to no growth in the equilibrium phase. Physically "K" could be
thought of as the carrying capacity of an ecosystem.
3. a. Size: 30 million in late 1996 (based on Statistics Canada’s recent
estimates). Projected to reach 35-40 million by 2035.
b. Growth rate: About 1.2% per year for the period 1991-96, with slightly
more than half of the growth coming from immigration.
Growth is slowing owing to smaller and smaller
contributions from the natural increase component.
c. Fertility rate: Slightly lower than 1.7 children per woman (circa
1994). If this trend continues, deaths will exceed births by
around 2030.
d. Age structure: Shows (circa 1996) a bulge at the 30-44 age groups.
These groups will contribute to the graying of Canada's population,
which will take place gradually at first and then at a more
accelerated pace after 2015.
e. Immigration: Its impact on Canada's population growth will likely
increase.
f. Other statistics (1995):
Birthrate: 13/1000
Deathrate: 7/1000
% of population over 65: 12%
% of population under 15: 20%
Infant mortality rate: 7/1000
Life expectancy: 78 years (81 years for women, 75 for men)
4. Essentially true. The principal factors contributing to inaccuracies in
the component (or cohort survival) method include changes in the age-
Page 42
specific fertility rates and mortality rates. Otherwise, the method
should give reasonably reliable projections, especially if they don't go
beyond 10 years or so. On the other hand, the assumptions and parameters
used in mathematical models are often unrealistic and do not represent
real world situations.
6-E
1. (a)r = b - d + i - e, where
r is the growth rate, in units like % per year,
b is the birth rate, in units like % per year,
d is the death rate, in units like % per year,
i is the immigration rate, in units like % per year, and
e is the emigration rate, in units like % per year.
(b)So decimals can be mostly avoided (e.g. 7 per thousand instead of 0.7
per hundred).
(c)b = 383,000 / 29,600,000 = 0.0129 = 1.29% = 12.9/1000
d = 213,000 / 29,600,000 = 0.0072 = 0.72% = 7.2/1000
2.
(a)If the effect of natural increase alone is considered, the growth rate
is
r = 23/1000 = 2.3% for Year 1. The growth rate remains the same for
Years 2 through 5.
(b) Year 1: 1000 x 1.023 = 1023
Year 2: 1023 x 1.023 = 1046.5 = 1047
Year 3: 1046.5 x 1.023 = 1070.6 = 1071
Year 4: 1070.6 x 1.023 = 1095.2 = 1095 (given as 1096 in the text)
Year 5: 1095.2 x 1.023 = 1120.4 = 1120 (given as 1121 in the text)
For the US and Hungary, the growth rates are so small that if only a
few years are considered, the compounding effects would not show up
clearly and therefore you could simply add a constant to the
population to get next year's population. However, in the case of
Costa Rica, the growth rate is relatively large, and the effect of
compound growth can no longer be ignored even for a period of only a
few years.
(c) Costa Rica's Year 5 Population = (2,850,000/1000) x 1095 = 3,121,000
(Or, using the figure of 1096 as given in the text, 3,124,000)
3. (a)Costa Rica's age distribution is shaped like a pyramid, the US age
distribution is shaped like a bowling pin (with the middle part
being a little wider), while Sweden's pattern shows essentially the
same width from top to bottom. It's the distributions of the
various age groups, particularly the size of the prereproductive
group as a percentage of the population, that allow one to make
projections. Other things being equal, a wide base translates into
rapid growth.
No, not all the necessary information is provided by age distributions.
You need, for example, data on age-specific fertility rates and
mortality rates when you make population projections.
(b)You can focus your attention on a specific age group and based on the
population size, sex ratio and average age in that group, try to
assess their impact on society as they grow older. The information
Page 43
could be useful for marketing, health care, occupational training
and other purposes.
4. Imagine pushing the Kenya age distribution (with the top three levels
removed) up three steps and that should approximate Kenya's age
distribution (minus the bottom three age groups) 15 years hence. As for
the bottom three age groups, approximate by using proportions. (This
approximation method, of course, will produce only ballpark figures, as
deaths in the 15-year span have not been taken into account, nor have the
number of newborns in this period been arrived at using age-specific
fertility rates.)
5. (a)t = 70 / r
where t is the doubling time in years, and
r is the annual compound growth rate in %.
(b)You can use it to find the doubling time, or if the doubling time is
known, to find the annual compound growth rate for any kind of
compound growth. But be aware that the result thus obtained is only
an approximation, and it has been implicitly assumed that first, the
type of growth under consideration is compound growth; and second,
the annual growth rate is constant over time.
(c)Except for the 0.2% growth rate, there is reasonably good agreement.
(d)Missing years: 1930 and 2019
Missing growth rates: 0.5% and 1.6%
Missing doubling times: 45 years and 44 years
Page 44
Chapter 7
7-A
Human Population Issues
TRUE-FALSE QUESTIONS
Where "F" is your answer, change the underlined portion (and the underlined
portion only) of the statement to make it true.
1.Much of the world's population increase in the next thirty years is
expected to occur in Africa, Asia and Latin America.
2.Canada's senior (65 and over) population, as a percent of the total
population, is projected to continue to grow - steadily at first, and
then more rapidly after around 2015.
3.Even as the annual growth rate continues to decline, the world's population
can still grow faster than ever before in absolute numbers.
4.A major non-biological factor that determines family size is the status and
education level of women in a culture.
5.The environmental impact of a population depends on its size rather than
its lifestyle.
6.A country that goes through the demographic transition experiences a
decline in the birthrate first, followed by a decline in the deathrate.
7.In the mid-1990s, Canada's total fertility rate (TFR) is approximately 2.8.
8.If Canada's 1996 population is divided into 15-year age intervals (0-14,
15-29, 30-44, ...), the largest group will be that aged 0-14.
9.For years, the TFR in both Canada and the US have been below replacementlevel fertility, but because of population momentum, natural increase is
contributing to their populations growth.
10. Crude birthrate is simply another term for birthrate.
7-B
MATCHING QUESTIONS
Match each of Q.1-7 with the most appropriate item from the following list.
Any item in the list may be used more than once, or not at all.
a. demoography
b. demographics
c. demographic transition
d. ZPG
e.
natality
f. generation X
g. baby boomers
h. life expectancy at
birth
1.When birthrate plus immigration rate equals deathrate plus emigration rate.
2.In Canada (circa 1994), it is about 81 years for women and 75 years for
men.
3.The group of people who were born between 1946 and 1965.
4.The group of people who were born between 1966 and 1980.
Page 45
5.Characteristics (often in the socio-economic context) of a population, such
as growth trends and distributions in age, sex, income or ethnicity.
6.Another term for crude birthrate.
7.The study of human populations, particularly the statistics on population
sizes, distributions, movements, growths, etc.
7-C
MULTIPLE-CHOICE QUESTIONS
1.Two different countries with the same rate of growth
a. must have the
same birthrate.
b. must have the same deathrate.
c. could have widely
different birthrates.
d. must have the same birthrate and deathrate.
2.Even if replacement-level fertility could be achieved worldwide tomorrow
and maintained in the years to come, it would still take approximately
years before world population would substantially stabilize. a. 30
b. 60
c. 100
d. 200
3.Which of the following does not materially influence the growth rate of a
population?
a. Natural resources available. b. Net migration rate.
c. Average living standard of a country.
d. State of the environment.
4. Zero population growth refers to
a. zero birthrate.
b. 2.1 children per
woman during her lifetime.
c. birthrate and immigration rate together
being equal to deathrate and emigration rate together.
d. slower growth rather than exponential growth of the population.
5.Which of the following is likely
a. More cattle will be raised to
ecosystems will be altered and
increase.
d. Tonnage of fish
to occur if the world population doubles?
feed the population.
b. More natural
destroyed.
c. Agricultural output will
caught from the ocean will double.
6.The total fertility rate is
a. the number of annual live births in a
population.
b. 2.1 children per woman during her lifetime.
c. the
average number of live births per woman during her child-bearing years.
d. the same as replacement-level fertility.
7.The most widely used parameter for fertility and for future population
projections is
a. replacement-level fertility.
b. the total fertility
rate.
c. the birthrate.
d. the rate of natural increase.
8.Canada's population reached/will reach 30 million sometime in:
a. 1995.
b. 1996.
c. 1997.
d. 2000.
9.In the developed countries, the average total fertility rate is about
children per woman per lifetime.
a. 1.5
b. 1.8
c. 2.1
d. 2.4
10.An infant mortality rate of 7/1000 means that each year
a. out of every
1000 people who die, seven are babies.
b. out of every 1000 births,
seven are stillbirths.
c. out of every 1000 live births, seven will die
Page 46
within the first year.
d. out of every 1000 live births, seven will die
before they are six months old.
7-D
QUESTIONS FOR REVIEW, RESEARCH AND CRITICAL THINKING
1. Distinguish between (a) population dynamics and demography; (b) rate of
growth and rate of natural increase; (c) birth rate, crude birth rate and
age-specific birth rate; (d) fertility rate, total fertility rate and
replacement-level fertility; (e) death rate, crude death rate and infant
mortality rate.
2. (a)What would be a reasonable estimate of world population in 1997?
(b)At what rate is world population growing today?
(c)What is the outlook for world population growth over the next 50 years?
3. It has been estimated that on a per-capita basis, North Americans are
responsible for 20-30 times more pollution than people living in nonindustrialized countries. What pollutant production, resource
consumption or other economic indicators do you think may have been used
for this estimate? Cite some current statistics to demonstrate that the
20-30 times figure is not just an exaggeration.
4. Explain the concept of population momentum. In particular, explain why,
for today's world population, growth would continue for 60 years or more
even if we were successful in reducing the annual rate of growth to zero
right away. Why is population momentum frequently linked to replacementlevel fertility and zero population growth?
5. (a)Describe three common methods used for (human) population projections.
(b)What useful purpose might (human) population projections serve? What
are the principal factors that may affect the accuracy of these
projections?
6. Replacement-level fertility varies from about 2.1 (children per woman
during her childbearing years) in developed countries to perhaps as high
as 2.6 in some developing countries. Why is the variation there? Why
does it take anywhere from 2.1 to 2.6 children - and not exactly two - to
replace two adults (the parents)?
7. "The study of human populations explains two-thirds of everything that
happens." True or false? Discuss.
7-E
WORKING WITH NUMBERS AND GRAPHS
1. Refer to Table 7.1.
(a)Using the UK data and the Zimbabwe data as examples, show
arithmetically that the values in the Rate of natural increase
column can be obtained from those in the Births per 1000 individuals
column and in the Deaths per 1000 individuals column. (Make sure you
don't mix up per 1000 with per 100.)
(b)Using the Sweden data and the Guatemala data as examples, show
Page 47
mathematically that the values in the Time needed to double
population column are linked to those in the Rate of natural
increase column by a simple equation.
(c)Explain why some countries with identical rates of natural
increase(e.g. 0.3% for the UK, Japan and Sweden) should have
substantially different doubling times, while others (also with
identical rates of natural increase, e.g. 2.8% for Ethiopia and
Afghanistan) should have exactly the same doubling times.
2. Assume Canada's mid-1996 population was 30.0 million. Assume also the
Canadian vital statistics given in Table 7.1 in your text are valid for
1996.
(a)Estimate the total number of deaths in Canada in 1996;
(b)Estimate the total number of infant (less than one year old) deaths in
Canada in 1996. Ditto for non-infant deaths. What was the ratio of
infant deaths to non-infant deaths?
(c)What was Canada's population growth rate, due to natural increase
alone, in 1996? If there had been no infant deaths in 1996, what
would have been the growth rate?
3. Suppose world population was 3.2 billion in 1965, and 6.0 billion in 1996.
Find the average annual growth rate, in %, for world population during
the 1965-1996 period. (Hint: Use either the compound growth formula or
the exponential growth formula to calculate the growth rate.) Which
year's world population is the reference base of your percent figure?
4. Refer to Fig. 7.4 in your text. If the original birthrate curve now became
the deathrate curve, and the original deathrate curve now became the
birthrate curve, what would the new size of population curve look like?
Show it in a graph.
5. Estimates of future population sizes are sometimes made with the formula P
= Po ert , where P is the future population size, Po is the initial
population size, e is the base of natural logarithms, r is the annual
growth rate expressed as a decimal, and t is the time elapsed in years.
Use this formula to estimate Canada's population five years from mid1996, if its mid-1996 population is 30.0 million, and the average annual
growth rate is 1.3% during this five-year period. Show your work.
6. Refer to Fig. 7.5 (age distribution of the US population) in your text.
Assume that the data was for the year 1995, and the 1995 population size
was 265 million.
(a)What was the male:female ratio for the 70-74 age group in 1995? And
for the 10-14 age group?
(b)About how many percent of the population in 1995 were the "Baby
Boomers?" And how many million people does that translate to? Show
your arithmetic.
(c)In 2010 (i.e. 15 years from 1995) how many people approximately will
there be in the 65-69 age group? Explain your answer.
7. Complete the following table, using information from the demographic graph
on China as given in Chapter 7 of your text.
Page 48
Birthrate
per 1000
Deathrate
per 1000
Annual growth
in %
Population size
in billions
Doubling
time in yrs
1965
1980
1995
On the basis of the figures you gave above, what general comments can you make
regarding China's demographic trends in recent years?
Page 49
Chapter 7
Answers and Solutions
7-A
T: Q.1, 2, 3, 4, 9, 10
F: Q.5, 6, 7, 8
Q.5
its size as well as its lifestyle
Q.6
a decline in the deathrate first, followed by a decline in the
birthrate
Q.7
1.7
Q.8
30-44
7-B
1d
2h
3g
4f
5b
6d
7a
7-C
1c
2b
3d
4c
5b
6c
7b
8b
9b
10c
7-D
1. (a)Population dynamics is the study of the factors that contribute to
changes in the size, distribution, movement, etc. of populations in
general. Demography is the study of human populations, especially
the statistics that relate to their distributions in space and time.
(b)Rate of growth (r) = Rate of natural increase + net migration rate.
Only when there is no net migration is the rate of natural increase
equal to the rate of growth.
(c)Birth rate is the same as crude birth rate (i.e. births per year per
1000 people). The word "crude" is sometimes included to allude to
the fact that people from different age groups and both sexes are
all lumped together in the calculation. Age-specific birth rate
refers to the number of births per year that come specifically from
every 1000 people in a certain age group, say 20-24.
(d)Fertility rate is the same as total fertility rate. It is the average
number of children born to a woman during her lifetime.
Replacement- level fertility is the average number of children each
woman would need to have in order to replace herself with one
daughter (or approximately speaking, it is the number of children a
couple must have in order to replace themselves).
(e)Death rate is the same as crude death rate (i.e. deaths per year per
1000 people). Infant mortality rate is the number of infant (0-1
year-olds) deaths per year per 1000 live births.
2. (a)6 billion.
(b)1.5%
(c)It will continue to grow, but the growth rate will probably moderate
over time.
3. Any of such indicators as per-capita greenhouse gas emissions, per-capita
solid waste production and per-capita energy consumption could have been
used. A very convenient, readily available figure to use, however, is
perhaps the per-capita GDP. For North Americans, that figure is about US
$27,000 during the mid-1990s. For the Kenyans, for example, it's about
US$1,200. The ratio is 23:1! While we shouldn't take such ratios too
literally, they nonetheless serve as useful indicators of the relative
Page 50
environmental impacts.
4. Population momentum refers to a growing (or declining) population's
tendency to continue to grow (or decline) even after the total fertility
rate has dropped below (or risen above) 2.1 children. Eventually, the
expected population decline (or growth) will occur, but there is a time
lag. For the world's population today, this time lag is estimated to be
60 years or longer. (The world's age distribution would have to undergo
a transformation, from a broad-based pyramid to a column of nearly equal
width from top to bottom. Such a transformation would take 60 years or
more.) Often, population momentum is used to demonstrate the fact that
we cannot expect to have ZPG right away even after replacement-level
fertility has been achieved, and that's why the three are linked
together.
5. (a) Component (Cohort survival) method: From present age distributions,
future age distributions are constructed using current age-specific
birth rates and mortality rates.
Curve-fitting method: Past population trends are plotted and fitted to
an equation (which can then be used for making projections); or the
population curve is simply extended into the future using recent
population trends and other available socioeconomic information as a
guide.
Ratio Method: When populaltion projections have already been made by a
reputable group, for a large geographical area that embraces your
municipality, say, then perhaps with some modifications to take care
of differences in growth between your municipality and the larger
area, you can use ratios of populations to estimate the future
population of your municipality.
(b)Planning. Reliabity is affected by changes in birth rates, death
rates, and social trends which in turn are related to the time
factor. One should be wary of any projections extending more than
ten years into the future.
6. Mortality rates are generally higher in developing countries, hence higher
replacement-level fertility is required. The requirement that the
replacement-level be higher than 2 is partly due to mortality rates, and
partly due to the sex ratio. (On a statistical basis, 200 babies, for
example, will not add 100 females to the population - even if there were
no mortalities at all.)
7. True to a certain extent, but maybe not as much as "2/3 of everything that
happens." There are many other cultural, technological, political or
economic factors that will influence people's behavior and decisions, and
just because the numbers are there doesn't necessarily mean that some
other things will also have to occur.
7-E
1. (a)U.K.: r = b - d = 1.4% - 1.1% = 0.3%
Zimbabwe: r = 4.1% - 1.1% = 3.0%
(b)Sweden:
t = 70 / r = 70 / 0.3 = 233 years (210 according to the
table; discrepancy is probably due to rounding off)
Guatemala: t = 70 / 3.2 = 22 years
Page 51
(c)Due to rounding. 0.3% implies it is in the 0.25% - 0.34% range, and
even though all three numbers are shown as 0.3%, in the actual
calculations, the more precise two significant digit numbers were
probably used, hence the different doubling times.
The doubling times for Ethiopia and Afghanistan are the same probably
because in the calculations, the same growth rate (2.8%) was used
for both countries. The 2.8% figure already has two significant
digits and could be used as it is.
2. (a)No. of deaths in Canada in 1996 = (30,000,000/1000) x 7 = 210,000
(b)Find the total number of births first:
No. of births = (30,000,000/1000) x 15 = 450,000
(The birthrate is actually 13/1000 or lower, but we'll use 15 here.)
Then find the number of infant deaths:
No. of infant deaths = (450,000/1000) x 6.8 = 3,060
Then find the number of non-infant deaths from subtraction:
No. of non-infant deaths = 210,000 - 3,060 = 206,940
The ratio of infant deaths to non-infant deaths is then given by:
3,060/206,940 = 1/68 (approx.)
(c)r = 1.5% - 0.7% = 0.8% (due to natural increase alone)
If there had been no infant deaths, then the total number of deaths
would have been 206,940 and the death rate would have become:
206,940/30,000,000 = 0.0069 = 0.69% (approx.)
The new growth rate would then be given by:
r = 1.5% - 0.69% = 0.81% (due to natural increase, and without infant
deaths)
In other words, the effect on the population growth rate would have
been minimal.
3. Using the compound growth formula, we get:
6.0 = 3.2 (1 + r)31
1.9 = (1 + r)31
(1.9)1/31 = 1 + r
1.021 = 1 + r
r = 0.021 = 2.1% (approx.), when averaged over the 31-year period.
The base changes with the year. Thus, for 1965, for example, the base is
the 1965 world population; for 1966, the base is the 1966 world
population, and so on.
4. Because the growth rate is now negative for the entire period, the
population size curve should trend downward all the way. The decline is
initially very gradual, then more rapid, and finally very gradual again.
5. N = 30.0 x 106 e0.013(5)
= 30.0 x 106 (1.067)
= 32.0 x 106 people in 2001.
6. (a)In 1995, Male:Female = 100:135 for the 70-74 age group;
Male:Female = 100:95 for the 10-14 age group.
(b)32%. In absolute numbers, that equals 265 million x 0.32 = 85 million.
(c)People who will be 65-69 in 2010 must have been 50-54 in 1995. From
the 1995 age distribution, we find that the 50-54 group constitutes
about 4.5% of the total population. In absolute numbers, that means
Page 52
265 million x 0.045,
that those people as
the 15-year span, we
age group in 2010 to
approximately.
or about 12 million people. If we then assume
a group experience a 15% mortality rate during
would expect the number of people in the 65-69
be equal to: 12 million x 0.85, or 10 million
7.
Birthrate
per 1000
Deathrate
per 1000
Annual growth
in %
Population size
in billions
Doubling
time in yrs
1965
42
10.5
3.2
0.76
22
1980
19
6.5
1.3
1.04
54
1995
18
6.0
1.2
1.22
58
In recent decades, China's population growth has slowed down dramatically - from
an annual rate of 3.2% in 1965 to 1.2% in 1995. This slowdown in growth has been
achieved largely as a result of government family-planning and population growth
control policies. China's total fertility rate in the early 1990s was about 1.9,
and trending downward. It appears that the Chinese population will stabilize or
start to decline some time in the second half of the 21st century.
Page 53
Chapter 8
8-A
Energy and Civilization: Patterns of Consumption
TRUE-FALSE QUESTIONS
Where "F" is your answer, change the underlined portion (and the underlined
portion only) of the statement to make it true.
1.In the mid-1990s, Canadian energy consumption amounts to approximately 56
barrels of oil equivalent per person per year.
2.In the last 2000 years, growth in global energy demand has outpaced growth
in world population.
3.Low-sulfur coal is coal that contains less than 3% of sulfur by weight.
4.Most of Canada's high-sulfur coal is located in western Canada.
5.At the current rate of depletion, Canada's conventional oil reserves are
projected to last another 28 years approximately.
6.About 50% of total global energy demand is supplied by fossil fuels.
7.OPEC stands for oil products exporting countries.
8.Even when coal is used as the fuel, tonnes of oil equivalent (toe) can
still be quoted as the energy units for the amounts of energy involved.
9.In the mid-1990s, almost half of the oil used in the US is imported oil.
10.One gigajoule is one trillion joules.
11.The relatively low retail prices of gasoline in the US and Canada, as
compared to those in other parts of the world, are almost entirely due to
the lower crude oil costs in North America.
8-B
MATCHING QUESTIONS
Match each of Q.1-7 with the most appropriate item from the following list.
Any item in the list may be used more than once, or not at all.
a. US and Canada
b. Japan and France
c. one US gallon
d. one imperial
gallon
e. one barrel of oil
f. fractional distillation
g.
synfuels
h. Canada
1. The equivalent of 4.5 L.
2.Approximately 159 L of oil.
3.Their government policies are to maintain low energy prices to spur growth.
4.Net exporter(s) of energy.
5.Petroleum refining.
Page 54
6.Liquid or gaseous fuels derived from solid fuels like coal or oil sands.
7.Their per-capita energy consumption is among the highest in the world.
8-C
MULTIPLE-CHOICE QUESTIONS
1.Fossil fuels are the remains of
a. plants.
c. microorganisms.
d. all of the above.
2.
b. animals.
was the first fossil fuel exploited by humans.
b. Wood
c. Coal
d. Oil
a. Methane
3.The very high per-capita energy consumption rate in Canada is mainly due to
its
a. energy-intensive industry.
b. cold climate.
c. large size.
d. inefficient, wasteful use of energy
4.In the mid-1990s, Canada is a net exporter of
c. coal.
d. all of the above.
a. oil.
b. natural gas.
5.The largest fraction of the energy used in homes and commercial
establishments in Canada goes to
a. lighting.
b. space heating.
c. air conditioning.
d. water heating.
6.Energy may be measured in all of the following units EXCEPT
a. tonnes of
oil equivalent.
b. tonnes of coal equivalent.
c. quads.
d.
kilowatts.
7.Which of the following fuels is the least-polluting?
Natural gas.
c. Oil.
d. Wood.
a. Coal.
8.The US, with less than 5% of the world's population, uses about
world's energy produced.
a. 10%
b. 15%
c. 20%
d. 25%
b.
of the
9.At the current rate of depletion, which of the following energy sources in
the world will mostly likely run out first?
a. Conventional oil.
b. Coal.
c. Natural gas.
d. Oil from oil sands.
10.Transporting people and goods account for about
of the energy used in
Canada and the US.
a. 15-20%
b. 25-30%
c. 35-40%
d. 45-50%
8-D
QUESTIONS FOR REVIEW, RESEARCH AND CRITICAL THINKING
1. (a)What amount of energy, in kilocalories (i.e. Calories), is needed to
meet the daily biological energy requirements of an "average"
American adult?
(b)How much energy, in kilocalories, do Americans as a people consume in
the early 1990s, on a per-capita per-day basis? How many times is
this amount larger than that you gave in (a) above?
(c)France, Japan and the UK are countries with industrial activities and
living standards comparable to those in the US. How do their per-
Page 55
capita per-day energy consumption rates compare with the figure you
gave in (b) above? If there are significant differences, suggest
reasons to account for them.
2. Consider energy consumption by humans from 1000 B.C. to 1990 A.D. Which
period (i.e. from what year to what year) would you identify as (a) the
Wood Era, (b) the Coal Era, and (c) the Oil-and-Gas Era? For the purpose
of this question, we will arbitrarily define an era as a period during
which a particular fuel (or combination of fuels) supplies more than 50%
of the total energy demand. (Note: Data on energy sources in recent times
are available from Fig. 8.5.)
3. Canada is often perceived as a country well endowed with fossil fuels. Is
that perception supported by fact? At current rates of depletion (i.e.
annual productions minus annual discoveries), about how many years would
Canada's proven reserves last in respect of (a) conventional oil, (b)
natural gas, and (c) coal?
4. (a)"Energy production and consumption are directly responsible for some of
the most critical environmental problems today." True or false?
Present your argument with examples.
(b)"When you reduce energy consumption, you get more benefit than just
saving fuels and money." What is the implication here? Elaborate.
5. The US government (and to a large extent, the Canadian government as well)
has been following a national policy of keeping energy prices
artificially low. What are the environmental, socioeconomic or
technological benefits, if any, of such a policy? What are the costs, if
any? On balance, do you think the benefits outweigh the costs, or vice
versa? Discuss.
6. Do you believe that achieving substantial energy savings (say, a 30%
reduction from present consumption levels) necessarily means a
substantial reduction in industrial activities and a lowering of the
living standard in this country? Explain.
8-E
WORKING WITH NUMBERS AND GRAPHS
1. Using information from Fig. 8.5, complete the following table:
% energy from wood
% from coal
% from oil
% from gas
% from others
1870
1930
1990
Check your % figures in each row to make sure that they do add up to about
100%.
2. Complete the following energy units conversion table, using these
Page 56
equivalents:
1.0 kilojoule (kJ)
=
=
=
=
=
=
=
=
=
=
=
=
kJ
= 1000 Joules (J)
2.8 x 10-4 kWh
0.24 Kcal
0.95 BTU
9.5 x 10-16 quad
2.3 x 10-8 tonne of oil equivalent (toe)
2.3 x 10-5 kg of oil equivalent
3.4 x 10-8 tonne of coal equivalent (tce)
1.6 x 10-7 barrel of oil equivalent (boe)
6.7 x 10-6 (US) gallon of oil equivalent
2.5 x 10-8 m3 of oil equivalent
2.5 x 10-5 L of oil equivalent
2.6 x 10-5 m3 of natural gas equivalent
kWh
Kcal
BTU
toe
tce
1 barrel of oil =
1 US gal of oil =
1 liter of oil =
1 m3 of oil =
1 kg of oil =
1 tonne of oil =
1 tonne of coal =
1 m3 of nat. gas =
1 quad =
3. Refer to the following table:
Year
Global energy demand in billion barrels
of oil equivalent per year
1990
64
2020
83 (Low estimate)
125 (High estimate)
(a)What is the average annual growth rate for global energy demand in the
1990-2020 period, based on the mean of the low estimate and the high
estimate for 2020?
Page 57
(b)Is the energy demand growth rate you obtained above higher or lower
than the projected world population growth rate in the 1990-2020
period? (For this part of the question, review the section on Human
Population Growth in Chapter 6.) Suggest reasons why the energy
demand growth rate should outstrip the world population growth rate,
or vice versa.
(c)In what regions of the world do you expect most of the growth in energy
demand to occur? Why?
(d)What fuels or energy sources are most likely to continue to supply the
bulk of the world's energy needs for the next three decades? Why?
4. According to Table 8.1 in the text, the per-capita per-year energy
consumption by Americans in 1992 was 7.67 toe. According to Table 8.2,
the per-capita per-year energy use by Americans for transportation in
1989 was 103 gigajoules (i.e. 1.03 x 1011 J). Ignoring the three-year
time difference for now, find the fraction of the total energy
consumption that was expended on transportation by Americans. (Hint: Use
the Table you just completed for Q.3 above.)
5. (a)Plot a line graph of the following data, using the vertical axis for
the energy generation data and the horizontal axis for the years.
Comment on the general shape of the line graph. Can you tell from
the line graph what the difference is between the 1900 electrical
energy generation figure and the 1910 figure?
(b)Plot a line graph of the same data, using a logarithmic vertical scale
this time. How does the general shape of this line graph differ
from the one obtained in (a) above? Can you tell from this line
graph what the difference is between the 1900 electrical energy
generation figure and the 1910 figure? What other features of this
semi-logarithmic graph have you noticed? (Note: You may have to ask
your instructor to show you how to construct a logarithmic scale
yourself.)
Year
US Electrical Energy Generation in kWh/person/yr
1900
50
1925
700
1950
2200
1975
8700
1990
11000
Page 58
Chapter 8
Answers and Solutions
8-A
T: Q.1, 2, 5, 8, 9
F: Q.3, 4, 6, 7, 10, 11
Q.3 less than 1% of sulfur
Q.4 eastern Canada
Q.6 85%
Q.7 Organization of Petroleum Exporting Countries
Q.10
one billion joules
Q.11
lower taxes on gasoline
8-B
1d
2e
3a
4h
5f
6g
7a
8-C
1d
2c
3d
4d
5b
6d
7b
8d
9a
10b
8-D
1. (a)About 2500 kcal.
(b)About 230,000 kcal/person/day, or 90 times the biological energy
requirement.
(c)Their consumption rates are about half of that in the US, on a percapita basis. This reflects the fact that energy is used
inefficiently or wastefully in North America.
2. According to the data in Fig. 8.5,
(a) Wood Era: 1000 B.C. - 1880
(b) Coal Era: 1882 - 1932
(c) Oil and Gas Era: 1942 - present
3. The answer depends on one's time frame: yes in the sense that at present
energy production is larger than domestic demand, and Canada is a net
exporter of natural gas, coal, oil and electricity; no in the sense that
at current (1996) rates of depletion, in less than 60 years all the
natural gas and conventional oil will have been depleted.
(a)Conventional oil: 28 years
(b)Natural gas: 55 years
(c) Coal: >200 years
4. (a)True. From energy production we get acid mine drainage, toxic
effluents, toxic emissions. From energy transportation we get oil
spills and pipelines in fragile environments. From energy use we
get greenhouse gas emissions, acid-forming pollutants, photochemical
smog and other harmful gases, vapors and particulates.
(b)The implication is that when you reduce energy consumption, you're also
helping to reduce air, water and other forms of pollution.
5. Benefits: All socioeconomic, such as helping industry - especially those
sectors whose operations require high energy consumption - to
grow and be competitive; reducing the inflationary pressure;
comfort and convenience made possible by cheap energy (e.g.
auto travel).
Page 59
Costs:
Rapid depletion of energy resources; acceleration of air
pollution, water pollution and other environmental problems due
to high energy consumption; rise of suburbia putting additional
stress on the environment; reliance on imported oil.
There is reason to believe the costs outweigh the benefits because the
costs have longer-lasting and more far-reaching impacts.
6. No. As we saw in our answer to Q.1(c), for North Americans large energy
savings can be achieved through more efficient use of energy.
8-E
1.
% energy from wood
% from coal
% from oil
% from gas
% from others
1870
75
25
0
0
0
1930
10
55
20
10
5
1990
0
20
41
27
12
2. One way to make conversions is by use of conversion factors. (A conversion
factor is simply the equivalency between two quantities written in the
form of a ratio.) Thus, to convert, say, 1 barrel of oil to its
equivalent in kilojoules, one proceeds as follows:
(1 barrel of oil) (1.0 kJ)/(1.6 x 10-7 barrel of oil) = 6.3 x 106 kJ
kJ
kWh
Kcal
BTU
toe
tce
1 barrel of oil =
6.3x106
1.8x103
1.5x106
5.9x106
1.4x10-1
1 US gal of oil =
1.5x105
4.2x10
3.6x104
1.4x105
3.4x10-3
5.1x10-3
1 liter of oil =
4.0x104
1.1x10
9.6x103
3.8x104
9.2x10-4
1.4x10-3
1 m3 of oil =
4.0x107
1.1x104
9.6x106
3.8x107
9.2x10-1
1.4
1 kg of oil =
4.3x104
1.2x10
1.0x104
4.1x104
1.0x10-3
1.5x10-3
1 tonne of oil =
4.3x107
1.2x104
1.0x107
4.1x107
1.0
1.5
1 tonne of coal =
2.9x107
8.2x103
7.1x106
2.8x107
6.8x10-1
1.0
1 m3 of nat. gas =
3.8x104
1.1x10
9.2x103
3.7x104
8.8x10-4
1.3x10-3
1.1x1015
2.9x1011
2.5x1014
1.0x1015
2.4x107
3.6x107
1 quad =
2.1x10-1
104 = 64 (1 + r)30
(1.625)1/30 = 1 + r
1.016 = 1 + r
r = 0.016 = 1.6% per year
(b)The energy demand growth rate is higher, as world population growth
3. (a)
Page 60
rate is projected to fall steadily from the current level of 1.5%.
Many of the nonindustrialized countries are now just beginning to
develop, and they will be using more energy in the years to come.
(c)In the developing countries in Asia, South America and Africa.
(d)Fossil fuels, because in the foreseeable future there are no other
major energy sources to replace them.
4. The ratio is
103 gigajoules
or
1.03 x 1011
or
In percentage terms, it is
: 7.67 toe,
J : 3.30 x 1011 J,
1 : 3.2.
about 31%.
5. (a)It is a curve showing growth that is more or less exponential in
nature. The difference in energy generation between 1990 and 1910
wouldn't show up too clearly because it is a relatively small number
in terms of the full range of values on the graph.
(b)The result now looks more like a line than a curve because of the
approximately exponential nature of the growth. (The growth was
explosive from 1900 to about 1930, less so from 1930-1980 and more
moderate after 1980.) It's now easier to determine the difference
in energy generation between 1900 and 1910 (about 65 kWh) because
smaller numbers at the bottom of the logarithmic scale are given the
same weightings (equal vertical distances) as larger numbers at the
top of the scale. Other features of the logarithmic scale include:
1) the scale is divided into 10-fold cycles (e.g. 10, 100,
1000,...); 2) within each cycle, divisions are not equidistant
(distances of separation getting progressively smaller at the top);
3) the scale begins with a non-zero number at the bottom.
Page 61
Chapter 9
9-A
Energy Sources
TRUE-FALSE QUESTIONS
Where "F" is your answer, change the underlined portion (and the underlined
portion only) of the statement to make it true.
1.It takes thousands of years for fossil fuels to form.
2.Whether a resource is renewable or nonrenewable depends very much on the
time scale we choose to use to view the processes involved.
3.A high carbon content makes lignite a low-grade coal.
4.An oil that has a relatively large amount of sulfur in it is said to be
"sour."
5.In Canada today, more coal is being extracted through underground mining
than surface mining.
6.Most of Canada's oil sands deposits are located in Alberta and British
Columbia.
7.After distillation and catalytic cracking, a barrel of crude oil yields
slightly more than half a barrel of gasoline.
8.Most of the coal consumed in Canada is for steel making.
9.Since 1900, cumulative growth in global energy consumption has far exceeded
cumulative growth in global population.
10.In the mid-1990s Canada leads the rest of the G7 countries (US, France,
Germany, Japan, Britain and Italy) in per-capita energy consumption.
11.Global hydroelectricity output is projected to increase six-fold by 2020,
and most of the growth is expected to occur in developed countries.
12.Despite the fact that Canada has sufficient coal to last over 200 years (at
current consumption rates), its share of the world's coal reserves is
less than 1%.
9-B
MATCHING QUESTIONS
Match each of Q.1-7 with the most appropriate item from the following list.
Any item in the list may be used more than once, or not at all.
a. active solar system
b. passive solar system
c. the Alaska Pipeline
d. the James Bay Power Project
e. biomass conversion
f. 27o C/km
g. natural gas
h. surface mining
1.The system has no moving parts and does not use any energy to transfer heat
within it.
Page 62
2.Where it is buried, it is insulated.
3.The method involves removal of the overburden.
4.It supplies about 25% of Canada's energy needs today.
5.It was vigorously opposed by the Crees of Quebec.
6.In some less-developed countries, methane digesters are being used for this
purpose.
7.It requires a pump and a system of pipes.
9-C
MULTIPLE-CHOICE QUESTIONS
1.Of the following sources, which supplies the most energy to the world
today?
a. Coal.
b. Nuclear power.
c. Hydroelectric power.
d. Solar power.
2.Currently, more than
hydroelectric power.
% of Canada's electricity generated comes from
a. 10
b. 20
c. 35
d. 50
3.As a unit of measure for oil, a barrel is equivalent to about
a. 42 Cdn (imperial) gal.
b. 160 L
c. 50 US gal.
d. 185 L
4.The largest of Canada's coal deposits are found in
and Nova Scotia.
b. Manitoba and Saskatchewan.
Columbia.
d. Quebec and Ontario.
.
a. British Columbia
c. Alberta and British
5.As a fuel, natural gas is less harmful to the environment than either coal
or petroleum because its combustion
a. releases fewer air pollutants.
b. produces less CO2 (for each unit of energy generated).
c. emits no
pollutants other than CO2 .
d. a and b but not c.
6.Most of the oil pollution at sea can be attributed to
a. oil tanker
accidents.
b. oil leaked and dumped on land, and residual oil
discharged with the water used for washing oil tanker holds.
c. natural
seepages.
d. ocean oil-drilling operations.
7.Which of the following is NOT a renewable energy source?
a. Solar energy.
b. Nuclear power.
c. Hydroelectric power.
d. Fuelwood.
8.
Anthracite is the most desirable type of coal to use on account of its
a. high heating value.
b. low sulfur content.
c. low cost.
d. a and
b but not c.
9.Only about
% of the hydropower potential worldwide has been tapped.
a. 6
b. 12
c. 18
d. 25
10.Less than
sources.
% of the world's energy supply comes from renewable energy
a. 5
b. 10
c. 15
d. 20
Page 63
9-D
QUESTIONS FOR REVIEW, RESEARCH AND CRITICAL THINKING
1. Are fossil fuels as the dominant energy sources of the world likely to be
replaced by alternative energy sources in the next 30 years? In the next
60 years and beyond? Which of the alternative energy sources discussed
in the text do you think show the most promise as being capable of
meeting all or most of our future energy needs? What negative impact
might these forms of energy have on the environment? Comment.
2. Of the fossil fuels used by us today, which is the least environmentally
damaging? Why? By switching to this fuel as much as possible, will we
be helping the environment? And if so, to what extent? Explain.
3. In drawing up a blueprint for an environmentally sound energy policy, what
do you believe should be the goals, and the pathways to these goals,
(a) in the near term (say, the next 30 years); and
(b) over the longer term (say, beyond the next 30 years)?
Give your reasons.
4. "Hydro in moderation is fine, but too much is a disaster."
(a) Paraphrase the above quote.
(b) Do you agree with the statement? Why or why not?
5. In recent years, Canada has been dubbed by some as Brazil of the North,
mainly on account of her forest management practices and hydro
overdevelopment. Where are the hot spots? What are the environmental
concerns? Who are the parties drawn into the conflict? What is the
current status?
6. While all crude oils - as mixtures - are not the same, they do possess some
common physical attributes as a group. Complete the following table for
crudes by giving the ranges of values within which they normally lie:
Specific
gravity
Carbon
content
(% by wt)
Hydrogen
content
(% by wt)
Sulfur
content
(% by wt)
Calorific
value
(MJ/kg)
7. Much has been made of the discovery of the very considerable amounts of oil
in the Hibernia Oil Field off Newfoundland. Just how large are the
reserves, in terms of barrels of oil? When is production scheduled to
start? How many additional years of oil supply will the reserves give
Canada, at current consumption rates? Has the Hibernia oil find
materially changed the overall oil supply picture of Canada? Discuss.
9-E
WORKING WITH NUMBERS AND GRAPHS
1. Estimates of reserves of oil, gas or coal are often quoted in terms of
Page 64
years of supply, but there appear to be two different interpretations of
this term, as detailed below:
A) Years of Supply (in the absence of any new discoveries)
= (Total proven reserves) ) (Annual production)
B) Years of Supply (based on the net annual depletion rate at present)
= (Total proven reserves) ) (Annual production - Annual discoveries)
Calculate Canada's remaining years of natural gas supply (with 1994 as the
base year) using the two methods given above and some or all of the data
that follow:
Q Canada's proven reserves of natural gas (as at 1994): 2700 x 109 m3
Q Canada's total gas production in 1994:
145 x 109 m3
Q Canada's gas exports in 1994:
65 x 109 m3
Q Canada's gas discoveries in 1994:
95 x 109 m3
2. Despite continuing growth in world population in the decades to come (which
we will assume to be 1.4% p.a. from 1995-2004, 1.0% p.a. from 2005-2014;
and 0.6% p.a. from 2015-2024), targeting and achieving an annual
reduction in energy consumption of 3% on a per-capita basis would
actually result in substantially lower global energy demand over the next
three decades.
(a)Show that according to the above assumptions, global energy demand in
2024 would be only about 54% of current levels.
(b)Do you think that it would be relatively easy and painless to achieve
an annual energy reduction of 3% throughout the 30-year period? How
would conditions in developing countries differ from those in
developed countries? Comment.
3. By completing the following table, demonstrate for yourself that in the
last 2000 years or so, the cumulative growth in global energy demand has
far outpaced the cumulative growth in global population.
World
Population
Average Percapita Energy
Demand
(Per Day)
10 B.C.
200 x 106
5 x 106 cal
1997
6100 x 106
47 x 106 cal
Page 65
World Energy
Demand
(Per Day)
Chapter 9
Answers and Solutions
9-A
T: Q.2, 4, 9, 10, 12
F: Q.1, 3, 5, 6, 7, 8, 11
Q.1
millions of years
Q.3
high water content
Q.5
through surface mining than underground mining
Q.6
Alberta and Saskatchewan
Q.7
slightly less than half a barrel of gasoline
Q.8
electric power generation
Q.11 less-developed countries
9-B
1b
2c
3h
4g
5d
6e
7a
9-C
1a
2d
3b
4c
5d
6b
7b
8d
9c
10b
9-D
1. In the next 30 years, most probably no. In the next 60 years and beyond,
most probably yes (we'd be close to running out of oil and gas by that
time anyway, even if we could escape the havoc of global warming). Of
the alternative energy sources discussed, solar energy and biomass
conversion are generally accepted as having the most promise. Aside from
some minor negative side effects, solar energy is clean and plentiful,
and would be our energy source of choice in the future if cost could be
brought down. Biomass conversion takes up land and could pose threats to
wildlife and biodiversity, but if properly planned its negative impact
could be reduced.
2. Natural gas. It produces 30-45% less carbon dioxide than oil or coal for
each unit of energy delivered. It also produces less sulfur dioxide and
nitrogen oxides. Natural gas therefore could be considered as a shortterm partial solution to our global warming and air pollution problems,
buying us time as we develop viable alternative energy sources. However,
for obvious reasons, natural gas is not a long-term solution.
3. Answers will vary, but perhaps should have the key elements of energy
efficiency and conservation, as well as the replacement of fossil fuels
by renewable energy sources over time.
(a) In the next 30 years
Goals:
- Reduce global energy demand (say, by 2025, to 70% of 1994 level).
- Reduce dependency on fossil fuels (say, by 2025, to 60% of total
energy demand for that year).
Pathways:
- Promote and target energy efficiency and conservation (through a mix
of economic, regulatory and suasive measures)
- Accelerate research and development on alternative energy sources.
(b) Beyond the next 30 years
Goals:
- Further reduce global energy demand (say, by 2050, to 50% of 1994
Page 66
level).
Further reduce dependency on fossil fuels (say, by 2050, to 20% of
total energy demand for that year).
Pathways:
- Continue to promote and target energy efficiency and conservation.
- Further expand the use of alternative energy sources. Develop
environmentally benign ways of using coal.
-
4. (a)Compared to thermoelectricity, hydroelectricity is renewable and clean,
and for such reasons would be a preferred source of energy.
However, this is not to say that hydro does not have its own
negative impact on the environment. In fact, the magnitude of its
environmental impact is often directly proportional to the size of
the hydro project itself: a massive hydro project can have
disastrous consequences on the people and the wildlife of the area.
(b)Yes. When large areas of land are flooded, when rivers are dammed and
their flows altered, fish, water fowl and other forms of wildlife
are all adversely affected or even decimated. The native people who
live off the land also suffer.
5.
Forestry
Hydro Development
Hot spots
a) Vancouver Island, B.C.
b) Temagami, Ont.
NW Quebec (area to the east of
James Bay)
Major
Concerns
a) Logging of old-growth
forests and loss of
biodiversity; b) Overlogging
and other logging practices
a) Fish and wildlife
destruction; b) soil erosion,
mercury-contaminated
water/fish and their impact on
native people
Parties in
conflict
Canadian forestry industry and
environmentalists
Hydro-Quebec vs the Crees of
Quebec and environmentalists
Current
status
a) B.C. Forests Practices Code
introduced in 1995; new parks
to be created; logging in
ecologically sensitive areas
to be curtailed. b) Logging
in Temagami proceeds as
planned
Phase II of the James Bay
Project has been shelved
because of power purchase
cancellation by New York and
opposition from the Crees and
environmentalists
6.
Specific
gravity
0.82-0.95
Carbon
content
(% by wt)
83-87
Hydrogen
content
(% by wt)
11-14
Sulfur
content
(% by wt)
1-6
7. About 620 million barrels of recoverable crude oil.
Page 67
Calorific
value
(MJ/kg)
43-46
Production is scheduled to start in December of 1997.
The Hibernia field would add about 1.3 years of oil supply to Canada's
existing stocks of conventional oil (which are projected to last another
28 years or so), and would not materially change the overall oil
inventory of the country. Unless Canadians curb their enormous appetite
for energy consumption, any attempts to find more oil/gas/coal may well
prove to be exercises in futility.
9-E
1. A) (2700 x 109 ) ) (145 x 109 ) = 19 (years)
B) (2700 x 109 ) ) [(145 - 95) x 109 ] = 54 (years)
As one can see readily from the above results, any years of supply figures
arrived at depend very much on the assumptions inherent in the method of
calculation used. (Note: the gas exports figure is irrelevant to the
calculation here.)
2. (a)First calculate the population increase factor, using 1 (one) as the
base.
2004:
1 (1+0.014)10 = 1.149
2014:
1.149 (1+0.01)10 = 1.269
2024:
1.269 (1+0.006)10 = 1.347
Next calculate the per-capita energy consumption factor, taking into
consideration an annual reduction of 3%. One (1) again is used as
the base.
2004:
1 (0.97)10 = 0.737
2014:
1 (0.97)20 = 0.544
2024:
1 (0.97)30 = 0.401
Finally calculate the global energy demand by multiplying the population
increase factor by the per-capita energy consumption factor
Global energy demand, 2004:
1.149 x 0.737 = 0.847 (i.e. about
85% of 1994 global energy demand)
Global energy demand, 2014:
1.269 x 0.544 = 0.690 (i.e. about
69% of 1994 global energy demand)
Global energy demand, 2024:
1.347 x 0.401 = 0.540 (i.e. about
54% of 1994 global energy demand)
(b)Achieving an annual energy consumption reduction of 3% (on a per-capita
basis) and maintaining it for three decades would be hard or even
painful. It would require planning, discipline and sacrifice. It
Page 68
would be especially hard for the developing countries, where
enormous pressure exists for improving the living standards through
economic development. The implications for the developed countries
are that if the world as a whole is to achieve a 3% reduction, they
may very well have to reduce their energy demand by more than that
rate, so as to make it a little easier for the rest of the world to
move toward that goal.
3.
World
Population
Average Percapita Energy
Demand
(Per Day)
World Energy
Demand
(Per Day)
10 B.C.
200 x 106
5 x 106 cal
1 x 1015 cal
1997
6100 x 106
47 x 106 cal
290 x 1015 cal
Whereas world population has grown about 30 times [(6100 - 200) ) 200 = 30]
over the last 2000 years or so, world energy demand has grown about 290
times [(290 - 1) ) 1 = 290] over the same period of time.
Page 69
Chapter 10
10-A
Nuclear Power: Solution or Problem?
TRUE-FALSE QUESTIONS
Where "F" is your answer, change the underlined portion (and the underlined
portion only) of the statement to make it true.
1.Isotopes undergoing natural radioactive decay emit particles, gamma
radiation, or both.
2.Nuclear disintegration takes place at a fixed rate for all kinds of
radioactive isotopes.
3.Nuclear power plants obtain their energy from nuclear fusion.
4.The most common type of power-generating reactors in use worldwide today is
the light-water reactor.
5.As released from nuclear processes, alpha particles and beta particles
cause equal amounts of biological damage.
6.The two fuels commonly used in nuclear reactors are uranium-235 and
plutonium-239.
7.The CANDU reactor, which is moderated and cooled by heavy water, was
developed by the Canadians in the early 1960s.
8.In Canada, nuclear power is produced in all ten provinces.
9.Reactors installed at Canadian nuclear power plants are all CANDU reactors.
10.In the mid-1990s about 25% of Canada's electricity production comes from
nuclear facilities.
11.To date, no Canadian nuclear power plants have been decommissioned.
12.An increased incidence of leukemia and Down's syndrome near the Pickering
(Ontario) nuclear power plant has been suggested, and the evidence is
strong.
10-B
MATCHING QUESTIONS
Match each of Q.1-7 with the most appropriate item from the following list.
Any item in the list may be used more than once, or not at all.
a. alpha radiation
b. uranium-235
c. uranium-238
d. 10,000 rems
e.
100 rems
f. boiling-water reactors
g. CANDU reactors
h. gamma
radiation
1.They are used in about 50% of the nuclear power plants in the world.
2.Their design permits the replacement of reactor fuel without shutting down
the reactor.
Page 70
3.Natural uranium contains about 99.3% of this isotope.
4.Enriched uranium contains about 3% of this isotope.
5.It can be stopped by a sheet of paper.
6.It can pass through several centimeters of concrete.
7.A single exposure to radiation of this magnitude would greatly increase the
likelihood of cancer and birth defects for humans.
10-C
MULTIPLE-CHOICE QUESTIONS
1.Energy released in nuclear fission is immense because
a. uranium is a
very efficient fuel.
b. energy associated with nuclear reactions is
immense.
c. the associated chemical reactions release large amounts of
heat. d. uranium has a higher density than coal or oil.
2.The half-life of a radioisotope is a measure of
a. its rate of nuclear
disintegration.
b. the intensity of its gamma radiation.
c. the
biological damage it causes.
d. its chemical reaction rate.
3.Most of the energy released in nuclear fission appears as
a. kinetic
energy of the fission fragments (barium and krypton).
b. kinetic energy
of the neutrons.
c. heat.
d. electromagnetic energy.
4.The current generation of fission reactors have an expected operating
lifetime in the range of
years.
a. 15-25
b. 25-35
c. 35-45
d. 45-75
5.Nuclear reactors are most commonly moderated by
water.
c. light water.
d. boron.
a. graphite.
b. heavy
6.Compared to electricity production by fossil fuels, nuclear power can be
considered cleaner because
a. it emits no air pollutants.
b. it
releases no water pollutants.
c. it generates no hazardous wastes.
d. it produces no carbon dioxide.
7.The nuclear power industry in Canada has declined in recent years on
account of all of the following reasons EXCEPT
a. high construction and
decommissioning costs.
b. negative public opinion about nuclear power.
c. a high incidence of mechanical failures and serious accidents.
d. concern over the long-term effects of radioactive wastes in the
environment.
8.All of the following items are low-level radioactive waste EXCEPT
a. protective clothing worn by persons working with radioactive materials.
b. spent fuel rods from nuclear reactors.
c. cooling water from
nuclear reactors.
d. uranium mine tailings.
Page 71
9. Thermal pollution is a greater problem with nuclear power plants than with
coal- or oil-fired generating plants because nuclear power plants
a. generally have larger generating capacities.
b. use a highly efficient
fuel.
c. have lower efficiencies in converting heat energy to
electrical energy.
d. use coolants that remove waste heat much more
quickly.
10.For the long-term management of high-level radioactive waste, Canada's
current emphasis is on
a. locating a suitable oceanic trench for
dumping. b. identifying deep, geologically stable caverns within Canada
for storage.
c. reprocessing the fuel rods and other highly radioactive
materials.
d. finding an economical way of sending it into outer space.
10-D
QUESTIONS FOR REVIEW, RESEARCH AND CRITICAL THINKING
1. "A big environmental plus for nuclear power is that it is clean in terms of
global warming, acid deposition and photochemical smog." True or false?
Elaborate.
2. Aside from real or imagined risks associated with reactor accidents and
radiation leaks during routine operations, two major problems with
nuclear power today relate to (a) the long-term safe disposal of
radioactive wastes, and (b) the escalating costs of nuclear power
production (from planning to decommissioning). Give the background on
and the contributing factors for each of these problems.
3. Distinguish between ionizing radiation and nonionizing radiation. Give
examples of each. Which type of radiation is implied when we speak of
the radiation dangers of nuclear power?
4. Identify and characterize our major concerns with each of the following
nuclear power hazards:
(a)Catastrophic nuclear power plant accidents;
(b)Radiation leaks/emissions in routine nuclear power plant operations;
(c)Contamination of the environment by radioactive wastes and byproducts.
5. Review the key issues and weigh the pros and cons of nuclear energy.
state and justify your position as to whether or not we should go
nuclear.
10-E
Then
WORKING WITH NUMBERS AND GRAPHS
1. Theoretically, the complete decay of a radioisotope requires an infinitely
long time, but for most practical purposes, a time of ten half-lives is
considered to be long enough to reduce the radiation level to a
negligible value. Take for instance iodine-131, which has a half-life of
8.1 days. How many days must wastes containing this radioisotope be
stored safely for the protection of the public?
2. How many years will it take for the radiation level of a sample of cobalt60 (half-life 5.27 years) to decrease to 10% of its initial value?
Page 72
3. Thermal pollution is one of the negative side effects of nuclear energy
production.
(a)What does thermal pollution mean? What does it usually refer to?
(b)Why does thermal pollution occur? Is thermal pollution unique to
nuclear power generation? What are the main physical/chemical
changes in the environment, and their biological consequences,
brought about by thermal pollution?
(c)For a nuclear power plant of 1000-megawatt generating capacity, what
rate of waste heat generation are we looking at? If 80% of this
quantity of waste heat is to be removed by 50 m3 of cooling water
per second withdrawn from a lake, what would be the temperature rise
in the cooling water when it is returned to the lake?
Page 73
Chapter 10
Answers and Solutions
10-A
T: Q.1, 4, 6, 7, 9, 11
F: Q.2, 3, 5, 8, 10, 12
Q.2
for any given radioisotope
Q.3
nuclear fission
Q.5
substantially different amounts of damage
Q.8
only three provinces (Ontario, Quebec and New Brunswick).
Q.10 14% of Canada's electricity production
Q.12 but the evidence is weak
10-B
1f
2g
3c
4b
5a
6h
7e
10-C
1b
2a
3a
4b
5c
6d
7c
8b
9c
10b
10-D
1. Largely true - largely but not completely because even though nuclear power
plants themselves do not produce CO2 , SO2 or NOx , some fossil fuels still
have to be used in other phases of the nuclear power cycle, e.g. in the
mining and processing of uranium, in the construction of nuclear power
plants, in the decommissioning of nuclear power plants, and so on.
2. (a)Initially nuclear scientists and engineers believed it would be
relatively simple to dispose of nuclear fuel wastes and other
radioactive byproducts by sealing them in secure containers and then
storing them far inside the earth in remote, dry and geologically
stable areas. The problem is: no one has yet found any geologic
formation that can be guaranteed to be dry and stable not just for
tens or hundreds, but for tens of thousands of years. The safe,
long-term disposal of nuclear wastes is probably the most serious
technical problem facing the nuclear industry today.
(b)Contrary to earlier anticipation that cheap nuclear power would soon be
available, the cost of nuclear power generation has actually gone up
dramatically in recent years. A number of factors have contributed
to this, including
- more stringent safety standards (higher construction and operation
costs of nuclear power plants)
- public opposition (delays in construction and startup, hence higher
overall costs)
- design and commissioning problems (higher startup/repair costs)
- more reactor "down" time and/or shorter-than-expected reactor lifetime
(higher costs of power generation)
- high decommissioning costs
3. Ionizing radiation refers to fast-moving subatomic particles (particle
radiation) and/or electromagnetic waves (electromagnetic radiation) that
come from both natural and human sources. This form of radiation is
called ionizing because the energy is high enough to knock electrons from
atoms (thus forming ions) in matter it impinges on. Examples of ionizing
radiation include alpha particles, beta particles, x-rays and gamma rays.
Page 74
Nonionizing radiation, on the other hand, is the lower-energy
electromagnetic waves, such as those coming from microwave ovens, radar
stations, CB radios and high-tension power lines. Nonionizing radiation
is not energetic enough to produce ions in matter it traverses.
Of these two forms of radiation, ionizing radiation is by far the more
dangerous to human health. The radiation arising from nuclear power is
the ionizing type.
4. (a)Catastrophic nuclear accidents: Although no reactor is "fail-safe,"
the probability of occurrence of such catastrophic accidents as
reactor blowups or meltdowns is very low. However, whether
warranted or not, concerns over this type of accidents persist,
perhaps not so much because of the probability factor, but rather
the horrific consequences of the unlikely catastrophe.
(b)Radiation leaks/emissions in routine operations: Very low levels of
radiation are continually leaked/emitted into the environment during
routine operations. While such levels of radiation are generally
insignificant compared to natural sources, they may still pose
threats to people living in the immediate neighborhood of nuclear
power plants. A few studies in recent years have linked birth
defects and other health problems to long-term exposure to such
sources.
(c)Radioactive contamination of the environment: Our concern here is with
the longer term. Hopefully, over the short term there are no leaks
from the storage sites and containers, but long-term containment is
a big unknown. As with reactor designs and operation, no disposal
methods are absolutely safe. Leaks and dispersal could lead to
widespread radioactive contamination of our food and our
environment.
5. Key issues:
- Safety concerns
(nuclear power plant accidents, radiation leaks/radioactive emissions
during routine operations, long-term disposal of radioactive wastes
and byproducts, power plant destruction caused by earthquakes, use of
reactor fuel for military purposes, exposure to terrorist activities)
- High costs
(construction and operation, commissioning and decommissioning, repairs,
waste disposal, etc.)
Pros:Relatively clean in terms of carbon dioxide, sulfur dioxide and
nitrogen oxides; less negative impact on land and water when
compared with the entire coal energy cycle.
Cons:The key issues of safety and cost remain largely unresolved.
Bottom Line: There are safer, cheaper and more efficient ways of
obtaining energy than going nuclear.
10-E
1. Ten half-lives in this case means 10 x 8.1 days, or 81 days.
2. The radioactive decay formula is N = No e-*t ,
where No is the initial radiation level, N is radiation level at time t,
Page 75
and * is the decay constant.
We first find the decay constant by use of the given half-life:
0.5 No = No e-*(5.27)
0.5 = e-5.27*
ln 0.5 = - 5.27*
* = (ln 0.5) / (-5.27) = 0.1315
We now put the value of the decay constant back into the original equation
to find the required time:
0.1 No = No e-(0.1315)t
ln 0.1 = - 0.1315t
t = 17.5 years (approx.)
3. (a)Thermal pollution is the release of waste heat into the environment.
Usually, the term refers specifically to the discharge of waste heat
into natural bodies of water, like rivers and lakes.
(b)Thermal pollution occurs because waste heat is always generated in
energy conversions and manufacturing processes. It is not unique to
nuclear power generation. The physical/chemical changes, along with
their biological effects, include
- severe water temperature fluctuations (adverse effects on some forms
of aquatic life)
- higher water temperatures (altered species composition)
- reduced dissolved oxygen in water (adverse effects on some species of
fish)
- increased chemical reaction rates (high concentrations of some
harmful/toxic chemicals in the water)
(c)Efficiencies of nuclear power plants are just a little above 30%; so
for every unit of energy generated, there will be about two units of
waste heat released. Accordingly, a 1000-megawatt nuclear power
plant would be releasing waste heat at the rate of about 2000
megawatts, or two billion joules of waste heat per second.
80% of 2000 megawatts = 0.8 x (2.0 x 109 ) watts
= 1.6 x 109 watts
= 1.6 x 109 joules/second
This much waste heat per second is now transferred to the cooling water,
such that
Waste heat discharged per second
= (Volume of cooling water intake per second) (Density of water)
(Specific heat of water) (Temperature rise in cooling water), or
1.6 x 109 J/s = (50 m3 /s) (1000 kg/m3 ) (4184 J/kg-o C) (Temp. rise)
Temperature rise = 1.6 x 109 / 2.09 x 108 = 7.7o C
Page 76
Chapter 11
11-A
Human Impact on Resources and Ecosystems
TRUE-FALSE QUESTIONS
Where "F" is your answer, change the underlined portion (and the underlined
portion only) of the statement to make it true.
1.Most of the wastes generated by humans in preindustrial times were nontoxic
and nonbiodegradable.
2.While representing only about 5.2% of the world population, North Americans
consume more than 30% of the minerals produced in the world each year.
3.Negative environmental effects of mineral extraction and processing
include, among other things, acid mine drainage, chemical contamination
of the environment, and sulfur dioxide emissions.
4.The vast majority of forest harvesting in Canada is done by selective
cutting.
5.The Canadian federal government's goal is to complete the proposed National
Parks System by the year 2000, but as of 1996, the system was only about
60% complete in terms of the distinct natural regions represented.
6.Clearcutting on sites with steep slopes is potentially less damaging to the
environment than clearcutting on sites that are relatively flat.
7.A species which could become extinct if a critical factor in its
environment were changed is an endangered species.
8.Sustainable forest management practices require that the rate of harvest be
balanced by the rate of regrowth.
9.The major goal of range management is maximizing livestock productivity
without overgrazing.
10. All renewable resources are living things.
11-B
MATCHING QUESTIONS
Match each of Q.1-7 with the most appropriate item from the following list.
Any item in the list may be used more than once, or not at all.
a. groundwater and forests
b. zebra mussels and sea lamprey
c. facing a
doomed future because of toxic chemicals in the estuary
d. Atlantic
salmon and rainbow trout
e. IWC
f. threatened by development and
commercialization
g. the Giant Panda and the Siberian Tiger
h. the
bald eagle and the grizzly bear
1.The St. Lawrence beluga whales.
2.Banff National Park.
Page 77
3.An international body that regulates whaling.
4.Examples of endangered species.
5.Depending on the circumstances, they can be either renewable or
nonrenewable resources.
6.Foreign species that were accidentally introduced into the Great Lakes.
7.Foreign species that were intentionally introduced into the Great Lakes.
11-C
MULTIPLE-CHOICE QUESTIONS
1.Which of the following costs are NOT normally recognized at first?
a. Labor costs.
b. Energy costs.
c. Environmental costs.
d. Transportation costs.
2.The most important cause of extinction of modern species related to human
activity involves
a. habitat alteration.
b. environmental pollution.
c. commercial hunting.
d. sport hunting.
3.A species may be more prone to extinction if it has
a. a high population
density.
b. high reproductive rates.
c. specialized feeding habits.
d. individuals generally short-lived and small in size.
4.Which of the following statements is NOT true of the northern spotted owl?
a. It lives in old-growth forests only.
b. It is an endangered
species.
c. It requires a very large area for hunting.
d. It feeds at
the top trophic level in old-growth food webs.
5.Desertification in arid or semiarid regions in recent decades has been
mainly caused by
a. urban development.
b. overgrazing.
c. deforestation.
d. all of these.
6.It is estimated that more than
% of all the species that have ever
graced the earth have now become extinct.
a. 20
b. 50
c. 90
d. 98
7.Exotic species that have entered the freshwater ecosystems of the Great
Lakes include all of the following EXCEPT
a. sea lamprey.
b. lake
trout. c. coho salmon.
d. zebra mussels.
8.All of the following are examples of external environmental costs EXCEPT
a. discarded mine tailings.
b. river water pollution caused by chemical
discharge.
c. energy costs in production.
d. acidic deposits on soil.
9.In 1994, the status of the
changed from an endangered to a threatened
species.
a. whooping crane
b. black rhinoceros
c. manatee
d. bald eagle
11-D
QUESTIONS FOR REVIEW, RESEARCH AND CRITICAL THINKING
Page 78
1. Cite examples to show that human impact on the environment today is (a)
more varied (in terms of ways to affect the environment), (b) more
intense (in terms of magnitude of effect and frequency of occurrence),
(c) more widespread (in terms of areal extent), and (d) more
unpredictable (in terms of consequences) than ever before.
2. Identify and analyze each of the following claims. In each case, what are
the reasons given for the claim? How good are the reasons given?
(a)"Sure, Temagami's got old-growth pines, but you've got old trees all
over the place. There's no reason why this region shouldn't be open
to logging. What we need is jobs - good-paying permanent jobs."
(b)"We cut the trees - they grow back. What's the problem? If we don't
cut them, bugs and fires will get them anyway. What's the point of
letting them fall and rot on their own?"
(c)"If we can stop the foreign plunder of our fishery resources off the
East Coast and the West Coast, our cod and salmon fisheries will
soon be alive and well again."
(d)"Yes, migratory birds and some plants may need wetlands, but we humans
don't!"
3. In the controversy over the logging of the old-growth forests in the
Pacific Northwest of the US, is the central issue one of the fate of the
northern spotted owl? Does the debate really come down to: Who's more
important, the logger or the spotted owl? How do you see it in the
larger context?
4. (a)How old are old-growth trees? Is there a specific threshold age for
them?
(b)What are the characteristics of a typical old-growth forest ecosystem?
(c)To date, about how many percent of their old-growth forests have the US
and Canada lost already? How do these figures compare with the
percent loss of tropical rainforests?
(d)In what ways, ecological or otherwise, are old-growth forests
important?
5. (a)What physical, chemical and biological parameters of water are people
alluding to when they use the term water quality? List two for each
category.
(b)When water quality is described as good or poor, in what sense is the
qualifier "good" or "poor" used?
6. Life-cycle analysis of a product is basically a cradle-to-grave approach to
examining the product's environmental impact. As an illustration of this
approach, apply the analysis to disposable diapers and cloth diapers.
Consider the pros and cons of each type and determine which would be a
better choice from the environmental impact perspective. Use the
following list as a guide.
Production: What raw materials are required? How are they extracted or
grown? What machinery, and how much energy and water are
used in the process? What pollutants are released?...
Use:
What's the energy requirement for their use? Does each use
cause water and/or air pollution? How does use affect
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Disposal:
human health and the health of ecosystems? How long do the
diapers last?...
How much landfill space will they take up? What toxic
chemicals will they release when decomposed? Does
biodegradability enter into the disposal picture?...
7. Negative environmental impacts caused by the mining industry include, among
other problems, acid mine drainage, metal contamination of the aquatic
environment and sulfur dioxide emission. For each, briefly describe
(a)how and where (in the mining and smelting process) the pollution
originates;
(b)effects of the pollution on air, land, water, and/or life;
(c) control measures being undertaken by the mining industry.
11-E
WORKING WITH NUMBERS AND GRAPHS
1. Suppose the data in Fig. 11.14 are applicable to a wildlife park 250 km2 in
area.
(a)What would be the harvestable surplus (i.e. the number of deer in the
park that may be killed) this fall?
(b)If only half of the harvestable surplus were harvested this fall, would
the deer population next spring be correspondingly larger? Explain.
2. The reproductive potential table for deer in Fig. 11.16 of your text has
been extended to the seventh year, as shown below. Supply all the
missing numbers.
Reproductive Potential - Deer
Adults
Yearlings
Fawns
Total
1st year
2
0
2
4
2nd year
2
2
2
6
3rd year
4
2
4
10
4th year
6
4
6
16
5th year
10
6
10
26
6th year
7th year
Do you think the deer population will actually grow as predicted by the
table? Why or why not?
3. The heights of the fully-grown Green Ash in a certain area are normally
distributed with a mean of 20 m and a standard deviation of 3 m. Find
the percent of Green Ash that are greater than 23 m. And the percent of
Green Ash that are between 18 and 24 m.
Page 80
Chapter 11
Answers and Solutions
11-A
T: Q.2, 3, 5, 8, 9
F: Q.1, 4, 6, 7, 10
Q.1
nontoxic and biodegradable
Q.4
clearcutting
Q.6
more damaging to the environment than
Q.7
a threatened species
Q.10 Not all
11-B
1c
2f
3e
4g
5a
6b
7d
11-C
1c
2a
3c
4b
5b
6d
7b
8c
9d
11-D
1. (a)Impact could be local or regional or global; short-term or long-term;
biochemical or geophysical, and so on.
(b)As demonstrated by the accelerated rates of species extinction, soil
degradation, farmland loss, urbanization, inland and estuary water
pollution, etc.
(c)Even the remote corners of the earth, the depths of the oceans and the
upper parts of the atmosphere are now negatively affected.
(d)Uncertainties reign in processes like global warming, long-term
exposure to toxic chemicals in the food chain and in the
environment, loss of biodiversity, to name a few.
2. (a) Claim:
Temagami's old-growth pines should be logged.
Reasons:
1. There're old-growth trees "all over the place."
2. Logging provides good-paying long-term jobs.
Reality Check:
1. About 2/3 of Canada's old-growth forests have disappeared. Few
old-growth trees remain in Ontario today.
2. Large-scale commercial logging as it is practiced in Canada
today is simply unsustainable. While logging provides goodpaying jobs now, these jobs will probably all disappear in
10-15 years' time, when the old-growth forests are gone.
Bottom Line:
Weak claim.
(b) Claim:
Logging makes common and economic sense.
Reasons:
1. Trees grow back naturally.
2. Trees will be destroyed by fires and bugs even if they are not
cut by humans.
Reality Check:
1. Trees do grow back, but the original community of insects, birds
Page 81
and animals won't. The new forest will be one of lower
biodiversity.
2. Trees destroyed by fires and bugs are returning nutrients to the
soil and providing food and shelter for many species of
organisms. The dying or dead trees actually are playing a
vital ecological role.
Bottom Line:
Very poor argument.
(c) Claim:
The collapse of Canada's cod and salmon fisheries is the direct
result of overfishing by foreign fishermen.
Reasons:
None.
Reality Check:
Canada has proclaimed a 370-km (200 nautical miles) Economic Zone,
which encompasses major portions of the best fishing grounds off
Canada's East Coast and West Coast. No doubt, there's
overfishing on the part of foreigners just outside Canada's
Economic Zone, which wouldn't help matters, but the basic cause
of the problem lies in years of overfishing by Canadian
fishermen themselves.
Bottom Line
Unsubstantiated, unwarranted claim.
(d) Claim:
Humans don't need wetlands.
Reasons:
Humans are not migratory birds or some species of plants, which need
wetlands for their survival
Reality Check:
Humans may not normally need wetlands for their survival, but do
need wetlands for the protection of their coastal areas from
wave action and erosion, of their lives and property during
floods, of their water quality by virtue of the filtering
actions of wetlands, and so on.
Bottom Line:
Weak claim.
3. The northern spotted owl may be viewed as a surrogate for the environment.
In the larger context, the debate boils down to: Which is more
important, the environment or economic growth and development? Where do
we draw the line?
4. (a)"Old" means different ages for different species of trees, but for most
species (and loosely speaking), "old-growth" means 200 years old or
older.
(b)Ecologically very complex and biologically very diverse. Many rare
species are found in old-growth forests.
(c)About 90% in the US and about 60% in Canada, according to some
estimates. These figures compare with an estimated loss of about
50% for tropical rainforests.
Page 82
(d)They represent an important part of our biological and cultural
heritage.
5. (a)"Water quality" is one of those terms that could mean different things
to different people.
Physical: Color; amount of total dissolved solids
Chemical: Amount of dissolved oxygen; concentrations of toxic chemicals
Biological: Biochemical oxygen demand; disease-causing microorganisms
(b)"Good" or "bad" with respect to the intended use of the water.
6. Accept all reasonable answers. A thorough analysis would be mind-boggling,
but most would probably suggest that cloth diapers are the better choice
of the two. To date, there seems to be no clear consensus among
researchers on this issue.
7. Acid mine drainage
(a)Mine tailings and effluent discharge; abandoned mines.
(b) Impairs water quality and harms aquatic life.
(c) Treat tailings and wastewater; use landscaping to control water
movement.
Metal contamination of aquatic environment
(a)Leaching of metals from tailings; emissions from smelting.
(b) Harmful to aquatic life, wildlife and humans.
(c) Use smokestack emissions-reducing devices and chemical treatment.
Sulfur dioxide emission
(a) Smelting.
(b) Harms plant life and animal life.
(c)Install scrubbers and use low-sulfur fuels.
11-E
1. (a)Harvestable surplus = 250 x 7.5 = 1875 = 1900 deer.
(b)No, because the carrying capacity of the park during the winter
wouldn't be enough to support a larger deer population anyway.
2.
Reproductive Potential - Deer
Adults
Yearlings
Fawns
Total
1st year
2
0
2
4
2nd year
2
2
2
6
3rd year
4
2
4
10
4th year
6
4
6
16
5th year
10
6
10
26
6th year
16
10
16
42
Page 83
7th year
26
16
26
68
No, because real-world conditions are rarely perfect or ideal.
3. Calculation of the z-scores and reference to the z-table will give the
required percentages here.
From elementary statistics, we have
z-score = (given value - mean) / standard deviation,
so for the Green Ash >23 m: z23 = (23 - 20) / 3 = 1
and from the z-table: when z = 1, 34% of the Green Ash are between 20 m and
23 m, which in turn means that 16% of the Green Ash are greater than 23
m.
To find the percentage of the Green Ash that lie between 18 m and 24 m, we
calculate the two z-scores separately, and then add the percents.
z24 = (24 - 20) / 3 = 1.3; z-table then gives a value of 41%.
z18 = (18 - 20) / 3 = - 0.67; z-table then gives a value of 25%.
Therefore 66% (i.e. 41% + 25%) of the Green Ash are between 18 m and
24 m.
Page 84
Chapter 12
12-A
Land-Use Planning
TRUE-FALSE QUESTIONS
Where "F" is your answer, change the underlined portion (and the underlined
portion only) of the statement to make it true.
1.In 1996, close to 60% of Canadians lived in urban areas.
2.As used in Canada, urban refers to built-up areas of 10,000 people or more,
and a population density of 1000 people or more per square kilometer.
3.Canada's population is not just becoming more urban, it is also becoming
more metropolitan.
4. A little over 4% of Canada's total land area goes to direct or indirect
urban use.
5.In Canada, more people lived in rural areas than in urban areas until about
the early 1940s.
6.Canada has a lot of land, but in percentage terms, only about 5% of the
land is cropland.
7.During the past ten years, property damage and the loss of life resulting
from floods worldwide have increased considerably.
8. Building higher dikes and levees is probably not the best long-term
solution to floodplain problems.
9.Seen through an employment lens, Canada's resources are much more urban
than natural.
10.Wetlands are land areas (excluding lakes, rivers, etc.) that are covered
with water year-round.
12-B
MATCHING QUESTIONS
Match each of Q.1-7 with the most appropriate item from the following list.
Any item in the list may be used more than once, or not at all.
a. zoning
b. Canada's "Main Street"
c. Asia
d. loss of farmland to
urbanization
e. tract development
f. South America
g. temperate
deciduous forests
h. temperate rain forests
1.It is a worldwide problem.
2.Planners use it to regulate land use.
3.They have trees like Douglas fir and redwoods.
4.They have trees like oak and maple.
5.The Quebec City to Windsor corridor.
Page 85
6.In recent years, this continent has had a higher rate of deforestation than
any other continent.
7.In recent years, more land was deforested annually on this continent than
any other continent.
12-C
MULTIPLE-CHOICE QUESTIONS
1.Unplanned urban growth is known as
a. urbanization.
c. tract development.
d. ribbon growth.
b. urban sprawl.
2.People are drawn to urban areas mainly by
a. entertainment facilities.
b. education opportunities.
c. job opportunities.
d. cultural
amenities.
3.The highest rate of urbanization in North America occurred/occurs in the
a. 1960s.
b. 1970s.
c. 1980s.
d. 1990s.
4.Currently, Canada's largest cities face all of the following challenges
EXCEPT
a. loss of manufacturing jobs.
b. insufficient budgets to
provide needed services.
c. urban sprawl.
d. high rates of population
growth in inner city areas.
5.One major problem with unplanned urban growth is that
a. growth occurs
only in good economic times.
b. movement into inappropriate area
occurs. c. many new subdivisions will be established.
d. local zoning
ordinances are not easily enforced.
6.Which of the following is NOT a useful aspect of wetlands?
a. Breeding
grounds for fish.
b. Increasing municipal water supply.
c. Natural
filter for runoff.
d. Protection of inland areas from wave action and
erosion.
7.In land-use planning, best use of the land has traditionally been
interpreted as all of the following EXCEPT a. increasing the municipal
tax revenue.
b. promoting industrial development.
c. zoning the land
for various kinds of use.
d. comprehensive planning incorporating
ecological principles.
8.All of the following are causes of soil degradation EXCEPT
a. flood
control measures.
b. overgrazing.
c. inappropriate agricultural
practices.
d. deforestation.
9.Over the past 30 years, Canada's prime agricultural land was being
converted to direct and indirect urban uses at an estimated rate of
km2 /yr.
a. 10
b. 100
c. 1000
d. 5000
10.According to a 1996 study by Worldwatch Institute, per-capita cropland
worldwide has decreased about
in the past 45 years.
a. 10%
b. 20%
c. 45%
d. 70%
Page 86
12-D
QUESTIONS FOR REVIEW, RESEARCH AND CRITICAL THINKING
1. (a)Define urban in your own words; then compare your definition with
Statistics Canada's definition. Did your definition come close to
the "official" definition? What moral can you draw from this
exercise?
(b)Do you think urban is defined differently in different countries? Why
or why not?
2. Give three specific examples of improper land use in or around your city.
3. (a)What is a green city? What is the primary design objective of a green
city?
(b)How would a green city deal with the issues of: i) transportation; ii)
waste; iii) housing; iv) energy use; and v) green space and parks?
12-E
WORKING WITH NUMBERS AND GRAPHS
1. Using data from Fig. 12.3 in the text, and from other sources, complete the
following table:
1960
Canada
US
1970
Canada
US
1980
Canada
US
1990
Canada
US
Urban population
in millions
Urban population
as % of total
population
Then based on data in the table, answer the following questions. For parts
(a) and (b), answers can be given for either Canada or the US.
(a)In the 1960-90 period, was there a continuing growth in urban
population in absolute numbers? And in relative numbers (i.e. as %
of total population)?
(b)To determine whether urbanization has been accelerating, stabilizing or
decelerating, which group of data - the urban population in millions
data or the urban population as % of total population data - would
serve as better indicators? Explain.
(c)What similarities and differences do you see between the Canadian data
and the US data for the 1960-90 period?
(d)The table above is an example of lumping different - in this case
Canadian and American - sources of data together for comparison. In
situations like this, what aspects of the data would you have to be
wary of in general?
2. The following data pertain to Canada's land area and agricultural land
area. All figures are approximate.
Page 87
Q Canada's total land and fresh water area: 10,000,000 km2 (=100%)
Q Agricultural land: 7% of Canada total
Q Prime agricultural land: 5% of Canada total
Q Class 1 agricultural land: 0.4% of Canada total
Q Agricultural land converted to urban uses, 1966-86: 3,000 km2
(a)Explain the terms agricultural land, prime agricultural land and class
1 agricultural land as they are used in Canada.
(b)At an assumed average density of 1700 people per square kilometer, how
large an increase in Canada's urban population (in terms of millions
of people) does the 3000 km2 of agricultural land conversion from
1966-86 represent? Check whether your answer is compatible with
population statistics on record.
(c)In terms of percent of Canada's agricultural land total, how much
agricultural land was lost to urbanization from 1966-86? At that
rate of conversion, how many years would it take urbanization to
claim half of Canada's agricultural land?
(d)In light of your answer to (c) above, and assuming that essentially the
same urbanization trend continues, give your reasons for supporting
- or rejecting - the claim that the loss of agricultural land in
Canada has been significant and looms as a serious problem.
Page 88
Chapter 12
Answers and Solutions
12-A
T: Q.3, 6, 7, 8, 9
F: Q.1, 2, 4, 5, 10
Q.1
78%
Q.2
1000 people or more; 400 people or more per square kilometer
Q.4
A little over 1% of Canada's total land area
Q.5
the early 1920s
Q.10 covered with water all or part of the time
12-B
1d
2a
3h
4g
5b
6c
7f
12-C
1b
2c
3a
4d
5b
6b
7d
8a
9b
10c
12-D
1. (a)Moral of the exercise: Definitions are important. Just because a word
is common does not mean you know its precise meaning in any context.
In Canada, for example, an urban area is defined as one having a
population of at least 1000 people and a population density of not
less than 400 people per square kilometer.
(b)Yes, principally because population sizes and densities of different
countries are widely different.
2. Accept all reasonable answers. Land use may be inappropriate for
aesthetic, conservation, public health/safety, future growth/development
or other reasons.
3. (a)A green city is a an environmentally-planned and environmentallyfriendly city. The primary objective in the design of a green city
is to make it as nearly sustainable as possible in its day-to-day
activities.
(b)Transportation: Encourage use of public transit; restrict use of
private cars in city center.
Waste: Promote waste reduction and recycling; provide appropriate
technology and facilities to deal with the city's wastewater and
solid waste.
Housing: Promote higher-density compact housing.
Energy use: Comprehensive program for energy-efficiency, e.g. public
education campaigns, promotion of energy-efficient homes and
solar energy utilization.
Green space: Reserve land for greenbelt and parks; preserve
wetlands.
Page 89
12-E
1.
1960
Canada
US
Urban
population in
millions
Urban
population as
% of total
population
1970
Canada
US
1980
Canada
US
1990
Canada
US
12.3
118
16.1
138
18.2
170
20.6
194
70%
67%
76%
68%
76%
78%
77%
78%
Note: The US population figures were derived entirely from the graph in
Fig. 12.3, and are being used here for illustration purposes only.
(a)Yes, continuing growth in absolute numbers from 1960-90.
Yes, continuing increase in relative numbers from 1960-90.
(b)The "Urban population as % of total population" data would serve as
better indicators because it is the % figures that are the measure
of urbanization.
(c)Similarities: In both countries the urban population component, as a
percentage of the total population, rose from around 70% to about
77% from 1960-90. The urbanization trends were similar.
Differences: The data suggest that for Canada, the rate of urbanization
was at its peak between 1960 and 1970, while for the US the highest
rate of urbanization occurred between 1970 and 1980. Also, in the
1960s and early 1970s, Canada was a more urbanized country than the
US, but after the mid-1970s the difference has narrowed.
(d)You have to be wary of the consistency and compatibility of the
different sets of data. In census data, for example, the definitions
used, the questions asked, the methods of collection and quality
control adopted could all be different. Result: even a simple
statement like "Seventy-eight percent of the population is urban"
could mean different things in different countries.
2. (a) Agricultural land: Includes cropland and grazing land. (In Canada,
agricultural land is often divided into 7 classes, class 1 being the
best quality.)
Prime agricultural land: Classes 1-3 agricultural land.
Class 1 agricultural land: The highest quality cropland.
(b)Increase in urban population from 1966-86
= 3000 km2 x 1700 people/km2
= 5,100,000 people
According to available statistics on population, the increase was about
4.6 million, so the above estimate seems quite reasonable.
(c)Agricultural land lost to urbanization, 1966-86, when expressed as % of
agricultural land total
= 3000 km2 /700000 km2 = 0.0043 = 0.43%
To convert half of Canada's agricultural land, it would take
(350000/3000) x 20 years, or 2333 years!
Page 90
(d)The problem is seen as one of quality of the land lost, rather than
quantity. Recall that only 0.4% (or about 40,000 km2 ) of Canada's
area is Class 1 agricultural land, much of which is in southern
Ontario. If one assumes that half of the agricultural land lost
between 1966 and 1986 was Class 1 land, then at that rate of
conversion, in about 100 years some 20% of Canada's best-quality
cropland will be permanently lost. And most people probably would
not view a loss of this magnitude in 100 years as insignificant.
Then there's also the urban shadow effect, which may raise the 20%
figure to 30% or higher.
Page 91
Chapter 13
13-A
Soil and Its Use
TRUE-FALSE QUESTIONS
Where "F" is your answer, change the underlined portion (and the underlined
portion only) of the statement to make it true.
1.Soil is a complex mixture of inorganic minerals and organic material.
2. The parent material and the climate are two important factors in
determining the type of soil formed.
3.Under ideal climatic conditions, soft parent material may develop into a
centimeter of soil within fifteen years, but more typically, the rate of
soil formation in Canada is about 0.5 cm per century.
4.A soil with a pH above 7.0 would be more productive for wheat and corn if
humus were added to reduce the acidity.
5. Soil structure refers to the relative abundance of sand, silt and clay in a
soil.
6.In a typical forest soil profile, the A-horizon is thinner than the Bhorizon.
7.The A-horizon of soil is commonly referred to as humus.
8.If a soil is too acidic, an alkaline substance such as lime can be added to
reduce the acidity.
9.In areas of high precipitation, the B-horizon is often poorly developed.
10.From a consideration of geographical factors alone, you would expect soil
erosion by water to be higher in B.C. than in the prairies.
11.During the mid-1990s, an estimated 25% of Canadian farmers are using some
method of conservation tillage.
12.In recent years, conservation tillage has been slowly but steadily gaining
acceptance among farmers across Canada.
13-B
MATCHING QUESTIONS
Match each of Q.1-7 with the most appropriate item from the following list.
Any item in the list may be used more than once, or not at all.
a. A-horizon
b. B-horizon
c. C-horizon
d. humus
e. loam
f. clay
soil
g. no-till farming h. summerfallow
1.This horizon is typically thicker at the bottom of a slope than on a slope.
2.It is the area below the subsoil.
Page 92
3.This horizon is usually thicker in grassland soils than in forest soils.
4.It is a soil best suited for plant growth.
5.Land is left unsown for a season to conserve moisture in the soil and to
allow accumulation of nitrogen.
6.This practice of farming accelerates soil erosion by wind and water.
7.It allows little water to infiltrate to lower layers.
13-C
MULTIPLE-CHOICE QUESTIONS
1.Which of the following statements about soil is NOT true?
a. Under most
conditions, soil is formed naturally at the rate of 1 cm every 50 - 100
years.
b. Soil is, in effect, a nonrenewable resource.
c. Soil is a
complex mixture of inorganic and organic materials, living organisms,
water and air.
d. A soil may have high fertility but low productivity.
2.Recent estimates placed the average depth of soil in Canada in the range of
a. 9 - 13 cm.
b. 14 - 18 cm.
c. 19 - 23 cm.
d. 24 - 28 cm.
3.Which of the following affect(s) soil formation?
a. Parent material.
b.
Parent material and climate.
c. Parent material, climate and
topography.
d. Parent material, climate, topography, living organisms
and time.
4.The pH of a soil
a. determines the types of plants it can support.
influences the uptake of nutrients by plants. c. would decrease if
sulfur were added to it.
d. all of the above.
b.
5.A clay soil has
a. good nutrient-holding capacity.
b. good waterholding capacity.
c. good water-infiltration capacity.
d. a and b but
not c.
6.Worldwide, the three most important causes of soil degradation today are
a. urban sprawl, hydro projects and highway construction.
b. mining,
farming and water diversion projects.
c. deforestation, overgrazing and
agricultural practices.
d. acid deposition, waterlogging and
desertification.
7.Each year, an estimated
tonnes of topsoil worldwide blows and washes
away from the surface of the earth.
a. 2.5 million
b. 2.5 billion
c. 25 million
d. 25 billion
8.A typical prairie soil
a. is a podzol soil.
b. is alkaline and dark in
color.
c. has a thick B-horizon that supports root growth.
d. all of
the above.
9.The benefits of conservation tillage include all of the following EXCEPT
a. reduced herbicide use.
b. reduced soil erosion.
c. improved soil
Page 93
moisture content.
d. decreased requirement for energy and labor.
10.According to the UN's Food and Agriculture Organization, the most severe
soil degradation is occurring in
a. Europe and North America.
b. Asia
and Africa.
c. Africa and S. America.
d. Australia and S. America.
11.Soil erosion in cropland can be reduced by all of the following EXCEPT
no-till or low-till farming.
b. conventional tillage methods.
contour farming and strip farming.
d. windbreaks.
a.
c.
12.Plowing
of the land.
a. increases the short-term productivity
b.
increases the long-term productivity
c. increases the short-term
productivity but decreases the long-term productivity
d. decreases the
short-term productivity but increases the long-term productivity
13-D
QUESTIONS FOR REVIEW, RESEARCH AND CRITICAL THINKING
1. Distinguish between soil degradation and soil erosion.
related? What are the principal causes of each?
How are they
2. "Soil is more than the weathered, decomposed materials of solid rock, more
than a mixture of gravel, sand, silt and clay..." What was the speaker
alluding to? Append sentences to the above quote to make its meaning
more explicit.
3. (a)Enumerate the major factors that influence the characteristics of
soils.
(b)Explain why grassland soils are usually alkaline, and have thick, dark
and incompletely leached A horizons.
(c)Explain why coniferous forest soils are usually acidic, and have
comparatively thinner, mineral-poor A horizons.
4. Currently some croplands in North America are losing topsoil at the rate of
10-15 t/ha/yr, which is at least 10-15 times the natural rate of soil
formation. That being the case, explain how there could have been a
layer of topsoil on those croplands in the first place. What does your
explanation suggest to you about the relationship between current
agricultural practices and soil erosion?
5. Elucidate the following statement: The damage caused by agricultural soil
erosion may be as costly off the farm as on the farm.
6. In view of the fact that soil conservation measures are widely known and
not too difficult to implement, are you surprised that soil erosion still
remains a serious worldwide problem today? Give your reasons.
13-E
WORKING WITH NUMBERS AND GRAPHS
1. Common ways to express soil erosion/formation rates include
(a) cm/yr (centimeters of topsoil per year),
(b) t/ha/yr (tonnes of topsoil per hectare per year),
Page 94
(c)m3 /ha/yr (cubic meters of topsoil per hectare per year), and
(d) tons (short) per acre per year.
Find the equivalency among them by completing the following conversion
equation:
1 t/ha/yr =
m3 /ha/yr =
cm/yr =
tons/acre/yr
For the purpose of this calculation, we will assume that on average,
topsoil weighs 1600 kg/m3 .
2. One farm in British Columbia is losing soil at the rate of 10 t/ha/yr,
while another farm in Iowa 10 tons/acre/yr.
(a)Which farm is losing soil at a higher rate? And how much higher?
(b)At its current rate of soil loss, how many years would it take the
British Columbia farm to lose 1 cm of its topsoil layer? And the
Iowa farm?
(c)If the above rates of soil loss represent moderate to fairly severe
cases, what does your answer to (b) above tell you about the nature
of soil loss?
3. Globally, soil erosion removes some 23 billion tonnes of topsoil each year.
If that amount of topsoil were deposited evenly on Canada's prime
agricultural land (about 500,000 km2 in area) each year, how thick a
layer would result in 50 years? (Assume as before that topsoil weighs
1600 kg/m3 .)
Page 95
Chapter 13
Answers and Solutions
13-A
T: Q.2, 3, 6, 8, 10, 11, 12
F: Q.1, 4, 5, 7, 9
Q.1
inorganic minerals, organic material, living organisms, air and
water
Q.4
increase the acidity
Q.5
Soil texture
Q.7
topsoil
Q.9
low precipitation
13-B
1a
2c
3a
4e
5h
6h
7f
13-C
1a
2b
3d
4d
5d
6c
7d
8b
9a
10b
11b
12c
13-D
1. Soil degradation refers to the deterioration of the life-supporting
capacity of soil, such as loss of organic matter, salinization, acidic
deposition, soil compaction, and so on. Soil erosion, on the other hand,
is the loss of topsoil through the actions of water and/or wind. It is
one of a number of processes leading to soil degradation. Of the two,
soil degradation is the broader term.
The principal causes of soil degradation include acidification,
salinization, waterlogging, compaction, erosion and loss of soil
nutrients. The principal causes of soil erosion include agricultural
practices (such as farming on slopes, overcultivating and overgrazing),
logging practices, mining operations, off-road vehicle use or other
recreational activities, road construction and urbanization.
2. The speaker was alluding to the fact that soil is not just a lifeless layer
of inorganic materials - rather, it is a living, dynamic ecosystem. In
addition to the inorganic minerals, soil has other abiotic components
like air, water and humus (all of which are important to living soil
organisms), and biotic components in the form of microbes and larger
animals. Soil organisms help recycle nutrients and maintain soil
fertility.
3. (a)Parent rock, climate, age (of soil), topography, vegetation, human
activities.
(b)Grassland soils are alkaline because capillary action during the drier
days brings much of the calcium carbonate (and other minerals) in
the B horizon back up to the A horizon. Their thick A horizons are
the result of high rates of weathering caused by the large diurnal
range in temperature during parts of the year. The A horizons are
incompletely leached because the amount of rainfall is relatively
small.
(c)Coniferous forest soils are acidic because the decaying vegetation is
acidic; their A horizons are thinner because the weathering is more
moderate, and mineral-poor because the higher precipitation in these
areas has led to extensive leaching.
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4. Rates of soil erosion in earlier times must have been much lower. Indeed,
the natural rates of soil formation must have exceeded the erosion rates
in much of historic and prehistoric times to give us a layer of soil
today. This suggests that high rates of soil erosion are relatively
recent phenomena, and that they are linked to human agricultural
practices and the intensive/extensive use of the land.
5. It has been estimated that the direct costs of soil erosion to America's
farmers, for example, amount to more than 10 billion dollars (and more
than 500 million dollars in Canada) a year. However, the indirect costs
(to the rest of the nation) are probably comparable. These off-the-farm
costs include:
- dredging of channels and harbors (necessitated by sediment deposition)
- destruction of fish habitat (due to sediment loading)
- higher costs of water purification (because of water pollution)
- lowered recreational value of waterways
6. One reason is that soil erosion is an insidious problem and as such, is not
normally a high-priority item for most governments. Another reason is
the extent and magnitude of the problem, which means that unless
rehabilitation measures were carried out with concerted efforts nationwide and worldwide, overall results would not be noticeable. Then there
are other causative factors that vary from country to country. In the
US, for example, farm programs designed to encourage maximum yield may be
counterproductive to soil conservation efforts. In some developing
countries, population increases, lack of financial resources, climatic
changes, ineffective conservation measures that have been imposed on the
farmers from above and from outside, have all contributed to the
persistence of the problem.
13-E
1.
1 t/ha-yr = 1000 kg/ha-yr
= (1000 kg/ha-yr) (1 m3 /1600 kg)
= 0.625 m3 /ha-yr
= (0.625 m3 /ha-yr) (106 cm3 /m3 ) (1 ha/108 cm2 )
= 0.00625 cm/yr
= (1000 kg/ha-yr) (2.205 lb/1 kg) (1 ton/2000 lb) (1 ha/2.47
acres)
= 0.446 ton/acre-yr
2. (a)
B.C. farm: 10 t/ha-yr
Iowa farm: (10 tons/acre-yr) [(1 t/ha-yr)/(0.446 ton/acre-yr)]
= 22.4 t/ha-yr
So the Iowa farm is losing soil at a higher rate. Its rate is 2.2
times that of the B.C. farm.
(b)First use the method of ratios to find the annual rate of soil loss.
For the B.C. farm, and letting x represent the unknown rate,
1 t/ha-yr : 0.00624 cm/yr = 10 t/ha-yr : x
x = 0.0625 cm/yr
Page 97
Therefore, it would take the B.C. farm 1/0.0625 years, or about 16
years to lose 1 cm of the topsoil layer.
Similarly, for the Iowa farm, the rate of loss is 0.140 cm/yr. So it
would take the Iowa farm 1/0.140 years, or about 7.1 years to lose 1
cm of its topsoil layer.
(c)What we have seen in this exercise is that soil erosion is an insidious
problem. Even in areas of fairly severe losses, the damage might
not be obvious until 10, 20 or 30 years later.
3. From elementary physics, we have:
volume = (mass)/(density),
so the volume of topsoil removed worldwide each year
= (23 x 109 x 103 kg/yr) / (1600 kg-m-3 ) = 1.44 x 1010 m3 /yr
In 50 years, the volume builds up to
1.44 x 1010 m3 /yr x 50 yr = 7.20 x 1011 m3
If the above volume of topsoil were deposited evenly on Canada's prime
agricultural land, it would result in a layer
(7.20 x 1011 m3 ) / (5.0 x 1011 m2 ) = 1.4 m = 140 cm in thickness
Page 98
Chapter 14
14-A
Agricultural Methods and Pest Management
TRUE-FALSE QUESTIONS
Where "F" is your answer, change the underlined portion (and the underlined
portion only) of the statement to make it true.
1.Slash-and-burn agriculture is typically practiced in the tropical parts of
the world with poor soil and high population densities.
2.Slash-and-burn farming requires a recovery time on the order of decades
before the forest can be cleared for another cycle of agriculture.
3.Despite its many problems and drawbacks, mechanized monoculture agriculture
over the last one hundred years has substantially increased the yields
per hectare of land farmed.
4.Approximately 50% of the world's crop yield today is estimated to be
directly attributed to the use of chemical fertilizers.
5. Carbon, sodium and calcium are often referred to as macronutrients of the
soil.
6.Soil fertility can be completely restored by the use of chemical
fertilizers.
7.One common problem with many chemical pesticides is that they kill target
organisms as well as non-target organisms.
8.In North America, virtually all uses of DDT have been banned since the
early 1970s.
9.Today, Canadian and American adults all have some DDT - from a few ppm to
more than 15 ppm - in their body fat.
10.In the Great Lakes basin, environmental levels of organochlorines that were
banned in the 1970s typically showed a downward trend from the mid-1970s
to the late 1980s, but in some places the downward trend was interrupted
around 1989.
11.In general, the half-life of a given persistent pesticide is longer in
tropical regions than in temperate regions of the world.
12.Our primary concern with the low concentrations of agricultural chemicals
in our water and food is not their acute toxicity, but their potential
long-term effect on human health and genetics.
14-B
MATCHING QUESTIONS
Match each of Q.1-7 with the most appropriate item from the following list.
Any item in the list may be used more than once, or not at all.
a. hard pesticides
b. soft pesticides
c. food additives
d. narrow-
Page 99
spectrum pesticides
g. micronutrients
e. broad-spectrum pesticides
h. auxins
f. macronutrients
1.Nitrogen and phosphorus are examples of them.
2.DDT and dieldrin are examples of them.
3.Compared with organochlorine pesticides, they are generally much more toxic
to humans.
4.They would kill only organisms within a selected group of species.
5.Zinc and manganese are examples of them.
6.They have relatively short half-lives, from hours to weeks.
7.They are natural growth regulators.
14-C
MULTIPLE-CHOICE QUESTIONS
1.All of the following are major types of agriculture EXCEPT
a. mechanized (industrialized) agriculture.
b. slash-and-burn
agriculture.
c. labor-intensive farming.
d. organic farming.
2.Which of the following is NOT a major drawback of slash-and-burn
agriculture?
a. Soil erosion.
b. Chemical contamination of soil.
c. Long recovery time.
d. Air pollution.
3.On a worldwide basis, approximately
a. 10%
b. 20%
c. 35%
d. 50%
of crops are consumed by pests.
4.The term pesticides refers to
a. insecticides.
c. herbicides.
d. all of the above.
b. fungicides.
5.The most widely used pesticides today are
a. herbicides.
fungicides.
c. insecticides.
d. rodenticides.
b.
6.Which of the following is an advantage of monoculture as compared to
polyculture?
a. Lower costs of food production.
b. Lower inputs of
chemical fertilizers and pesticides.
c. Better control of insect pests.
d. Better control of weeds.
7.Mechanized agricultural systems are prone to all of the following EXCEPT
a. soil erosion.
b. loss of organic matter from soil.
c. insect pest
outbreaks.
d. lower yields per unit of land.
8.Which of the following synthetic pesticides are NOT one of the three groups
discussed in the text?
a. Organochlorines.
b. First-generation
pesticides.
c. Carbamates.
d. Organophosphates.
9.Biological amplification is mainly related to the
Page 100
of the organism.
a. age
b. weight
c. trophic level
d. sex
10.An ideal pesticide would be
a. toxic to the target organism only.
b. non-persistent.
c. inexpensive.
d. all of the above.
11.Which one of the following chemical properties is NOT typical of most of
the organochlorine insecticides?
a. High toxicity to insects. b. High
toxicity to humans.
c. Stability against decomposition in the
environment.
d. Low solubility in water but high solubility in fat.
12.Those who practice organic farming use a. a system of integrated pest
management.
b. no pesticides.
c. no pesticides or chemical
fertilizers.
d. a and b but not c.
14-D
QUESTIONS FOR REVIEW, RESEARCH AND CRITICAL THINKING
1. (a)How would you characterize North America's industrialized agricultural
systems in terms of fossil fuels input, synthetic chemicals input,
manual labor input, irrigation water input, capital input, farm
size, crop yield and crop diversity (for a given farm)?
(b)In what ways is this type of agriculture unsustainable?
(c)What are the negative environmental impacts of this type of
agriculture? Discuss.
2. (a)It is often said that synthetic fertilizers degrade soils. To what
extent is this a fact? In what ways are soils degraded by synthetic
fertilizers?
(b)If synthetic fertilizers indeed degrade soils, how do you explain the
paradox that increased uses of these fertilizers have contributed to
higher crop yields in recent times?
3. Elaborate on the following two statements:
(a)Subsidized irrigation often has a snowball effect.
(b)Increasing consumption of pesticides primarily reflects the fragility
of modern monoculture crop farming and the diminishing success rates
of pesticides in recent years.
4. Explain why we are particularly concerned with the long-term effects of
pesticides of the chlorinated hydrocarbons family. In this regard, how
does biological amplification enter into the picture?
5. What chemicals, and what effects of them, did Rachel Carson draw attention
to in Silent Spring (1962)? Why is her work considered to be of such
great significance in the development of the environmental movement?
6. (a)What is the pesticide treadmill?
(b)How can we as consumers help farmers break out of the pesticide
treadmill?
(c)What can individuals do to reduce their exposure to risks from
pesticides?
7. How can we reconcile the need to maintain or increase agricultural output
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with the need to reduce the environmental damage of agriculture?
are our options?
14-E
What
WORKING WITH NUMBERS AND GRAPHS
1. The solubility s, in kilograms per cubic meter of water, of a certain type
of chemical fertilizer is given by s = 155 + 5.0T + 0.22T2 , where T is
the temperature of the water in degrees Celsius. If the solubility is to
be 350 kg/m3 , how warm would the water have to be? Find the required
temperature graphically.
2. The number N of insects remaining alive t hours after applying a synthetic
insecticide (for t < 10) varies inversely as 0.3t2 + 1. If there are
initially 855,000 insects in the area, how many percent of the original
insect population will remain 8.0 hours after an application?
3. Each application of an insecticide destroys 85% of a certain insect
population. How many applications are needed to destroy at least 99.9%
of the insect population?
Page 102
Chapter 14
Answers and Solutions
14-A
T: Q.2, 3, 7, 8, 9, 10, 12
F: Q.1, 4, 5, 6, 11
Q.1
with poor soil and low population densities
Q.4
25%
Q.5
Nitrogen, phosphorus and potassium
Q.6
can only be partially restored
Q.11 shorter
14-B
1f
2a
3b
4d
5g
6b
7h
14-C
1d
2b
3c
4d
5a
6a
7d
8b
9c
10d
11b
12c
14-D
1. (a)North America's industrialized agricultural systems may be
characterized as energy-intensive, fertilizers-intensive,
pesticides-intensive, irrigation water-intensive, capital-intensive,
fossil fuel-based (mostly oil and natural gas), mechanized (little
manual labor), large-scale (farm sizes of 200 ha or larger), highyield (when compared with subsistence farming), single-cropping, and
environmentally damaging and unsustainable.
(b)Unsustainable in several different ways: first, the soil cannot sustain
this type of farming which impairs its longer-term fertility and
productivity; second, our dwindling fossil fuels base cannot sustain
this kind of energy-intensive farming; and thirdly, our water
resources cannot sustain the (irrigation water) demand or the stress
(groundwater pollution and surface water pollution) exerted by this
type of farming.
(c)Among other negative impacts: soil degradation (erosion, salinization,
loss of soil fertility, etc.); depletion/pollution of groundwater;
pollution of rivers, lakes and estuaries (eutrophication, pesticide
pollution, sediment loading, etc.); air pollution (pesticide
spraying, operation of heavy machinery, dust, etc.); loss of
biodiversity (monocropping, disappearance of wildlife habitat,
etc.).
2. (a)True, to the extent that even if synthetic fertilizers do not degrade
soils over the short term, they impair soil fertility over the
longer term. It is not so much that inorganic fertilizers contain
"harmful" things and therefore directly degrade soils, but rather
that they don't restore all the lost nutrients to soils. The lack
of humus and micronutrients in chemical fertilizers makes for soil
compaction, decreased biological activity, and reduced fertility,
hence soils become "degraded."
(b)In a way, inorganic fertilizers for plants are like junk foods for
humans - you won't see the negative effects right away. Since N, P
and K are the macronutrients, and so long as they are applied in
plentiful quantities to the soil, crop yields will increase, at
least initially. It is only after a number of years, when the soil
Page 103
becomes severely compacted and depleted of its micronutrients and
organic matter, that the damage becomes obvious.
3. (a)When irrigation water is cheap, it leads to not only high consumption
and wastage on existing farmland, but also the expansion of
agriculture. This in turn places further demands on water supplies.
(b)1. Monoculture crop farming is ecologically unstable and more prone to
attacks by pests. So pesticides have to be applied more frequently.
2. Pests become resistant to pesticides over time, so larger and
larger amounts of pesticides have to be used.
4. Because they are persistent, portions of the initial amounts remain in the
environment for many years, and eventually become widely dispersed. Once
they get into the food chain, biological amplification sets in.
Organisms at or near the top of the food pyramid, including humans, would
suffer the most. Aside from their impact on wildlife, these toxic
chemicals have been linked to a wide range of harmful effects on human
health and genetics.
5. Synthetic persistent pesticides, such as DDT, and their potential long-term
damage to all forms of life. Her scholarly work was instrumental in
heightening public awareness of environmental matters in general, and
ushered in a new era of environmental movement.
6. (a) It refers to the vicious cycle of having to use more and more pesticide
over time (as genetic resistance, pest resurgence and secondary pests
develop) until finally the pesticide becomes virtually useless for pest
control. Switching to a new or different kind of pesticide would only
serve to perpetuate the vicious cycle.
(b)Some of the things we can do include:
- Accept fruits and vegetables that are less than perfect in appearance
- Buy products that are organically grown
- Demand stricter requirements on allowable pesticide residues in
agricultural products
- Lobby governments to ban or restrict the use of the most toxic
pesticides
(c)All of the things listed in (b) above also apply here. In addition,
individuals can
- Grow their own fruits and vegetables
- Scrub/wash/peel/discard/cook produce from super markets
- Eliminate/reduce pesticide use on their lawns/in their homes
7. Maintaining/increasing agricultural output and preserving the environment
need not be mutually exclusive (unless one assumes that industrialized
farming is the only viable form of agriculture). In fact, without
preserving the environment, long-term agricultural productivity will be
doomed. One option is to switch to sustainable agriculture. While its
principles are universal, sustainable agriculture as practiced in
different parts of the world must take into consideration local
environmental (climate, soil, topography, water/energy resources...) and
socioeconomic (land use and ownership, capital availability, food supply,
tradition...) conditions. The use of appropriate technology would also
Page 104
help. Ultimately, though, the size of the world population must be
stabilized.
14-E
1. Set up a table of values for T and s by assigning different values to T and
using the given equation to find the corresponding values of s, e.g.
T (o C)
s (kg/m3 )
5
10
15
20
25
186
227
280
343
418
When the data above are plotted, with T on the x-axis and s on the y-axis,
a rising curve results. The curve shows that when s = 350 (kg/m3 ), the
corresponding value of T is 20.5 (o C).
2. The inverse variation means that
N(0.3t2 + 1) = a constant.
When t = 0, N must be the initial population, so from the formula we have
855,000(1) = a constant, and the constant is just 855,000 itself.
N[(0.3)(8.0)2 + 1] = 855,000
or N = 855,000 / 20.2
= 42,300 (approx.)
In percentage terms, 42300 / 855000 = 0.050 = 5.0%
When t = 8.0 (hours), we have
3. If 85% of the insect population is killed, 15% survives.
Therefore, we require (0.15)n # 0.001
n log 0.15 # log 0.001
n (- 0.824) # (- 3)
n $ (-3) / (-0.824) $ 3.64
or n = 4 (applications)
Page 105
Chapter 15
15-A
Water Management
TRUE-FALSE QUESTIONS
Where "F" is your answer, change the underlined portion (and the underlined
portion only) of the statement to make it true.
1.Worldwide, the stocks of groundwater are five times as much as the water
supply in all the rivers and lakes.
2.Most of the water we use domestically in Canada goes to cooking and
laundry.
3.On the average, water vapor stays in the atmosphere for about 30 days
before returning to the earth as rain or snow.
4.Compared to river flows, groundwater movement is generally very slow.
5.More water evaporates from land than falls on it.
6.Typically, one-third or more of the irrigational water used in North
America never gets delivered to the roots of the plants due to losses
through evaporation.
7.The hydrologic cycle not only recycles water, but also purifies it.
8.Deforestation and compaction of soil in the catchment area will increase
the frequency of both floods and droughts.
9.Liter for liter, gasoline costs about 1000 times more than municipal water
in Canada today.
10.According to recently-released UN figures, about one-tenth of the world's
5.8 billion people today do not have access to clean drinking water.
11. One hundredth of one percent of the world's stocks of water sustains all
life on land.
15-B
MATCHING QUESTIONS
Match each of Q.1-7 with the most appropriate item from the following list.
Any item in the list may be used more than once, or not at all.
a. safe drinking water
b. groundwater
c. icesheets and glaciers
d. a confined aquifer
e. an unconfined aquifer
f. E. coli
g. toxic
chemicals
h. an example of tertiary treatment
i. water contained in
the atmosphere at any one time
1.The world's second largest source of fresh water.
2.Often used as an indirect measure of the concentration of disease-causing
organisms in the water.
3.If the average coliform count is no more than 1 per 100 mL of water.
Page 106
4.An artesian well.
5.Removal of phosphorus and nitrogen from the wastewater.
6.Its importance to us lies not in its quantity but in its short cycling
time.
7.Its upper water surface is called the water table.
15-C
MULTIPLE-CHOICE QUESTIONS
1.Which of the following constitutes the largest amount of water used in
Canada?
a. Industrial use.
b. Agricultural use.
c. Domestic use.
d. Business use.
2.Which of the following statements is NOT true of water?
a. Its molecules
behave like electric dipoles.
b. It expands when heated in the 0-4o C
range. c. It is lighter as a solid than as a liquid.
d. It has a high
heat capacity compared to most other liquids.
3.High levels of BOD in water generally indicates high levels of
in the
water.
a. dissolved oxygen
b. industrial waste
c. organic waste d.
toxic chemicals
4.Primary sewage treatment removes
from wastewater.
a. most of the
suspended and dissolved pollutants
b. mostly pathogens
c. mostly BOD
d. most of the suspended particles and some of the organic waste
5.Most of the industrial use of water in Canada is for
a. steel production.
b. paper production.
c. cooling purposes.
d. oil refining.
6.Currently, some
of the Canadian population is still not served by any
kind of municipal wastewater treatment at all.
a. 5%
b. 10%
c.
30%
d. 50%
7.According to your textbook, which of the following is NOT one of the five
common types of contaminants in the North American tap water today?
a. lead
b. mercury
c. chlorinated solvents
d. THM
8.Which of the following statements about dissolved oxygen (DO) in natural
waters is incorrect?
a. DO concentrations are sometimes given in mg/L.
b. A DO level of more than 8 ppm generally indicates cool, unpolluted
water. c. Warmer water can dissolve more oxygen than cooler water.
d. High BOD levels are usually associated with low DO concentrations in
the water.
9.Scientists commonly use
to express the concentrations of toxic
chemicals in water.
a. ppm only
b. ppm and ppb
c. ppm, ppb and
ppt
d. none of these units
10. Potable water is water that
a. is fit to drink.
Page 107
b. has a microbial
level of no more than one coliform per 100 mL.
c. is colorless and
odorless.
d. contains less than 0.05% of dissolved solids.
15-D
QUESTIONS FOR REVIEW, RESEARCH AND CRITICAL THINKING
1. Freshwater (and, except for the density property, seawater as well) is said
to possess many unusual properties, such as those related to
(a)
heat capacity, (b) latent heats of fusion and vaporization,
(c) solubility, and (d) density. For each of these properties, explain
first why water's behavior is considered unusual, and then comment on the
environmental impact of that unusual property.
2. (a)What is an aquifer? What is the connection between groundwater and
aquifers?
(b)Describe how an unconfined aquifer differs from a confined aquifer in
i) type of rock/sediment layer at the upper and lower boundaries of
the aquifer; ii) location of the aquifer recharge area;
iii)
water pressure within the aquifer.
(c)What human activities in recent years have adversely affected
i)
the quality, ii) the recharge rate, and iii) the available quantity
of groundwater in North America? What corrective measures would you
suggest?
3. Distinguish between water withdrawn, water consumed, and water returned.
Show their relationship in a word equation.
4. In view of the earth's huge stocks of groundwater, do you think groundwater
offers the potential for solving the water shortage problem worldwide?
What are some problems encountered in tapping this source of water
supply? Elaborate.
5. Complete the following table for the major categories of water pollutants:
Pollutant category
Key indicator
Units of measurement
Main sources
Organic wastes
Pathogenic organisms
Plant nutrients
Toxic chemicals
Waste heat
6. Complete the following table for the different types of wastewater
treatment indicated:
Type of
treatment
Principle
involved
Types of pollutant
removed by treatment
Page 108
Types of pollutant
remaining after treatment
Primary
Secondary
Tertiary
7. Some parts of the world already are, and some more parts will likely be,
experiencing potable/industrial/agricultural/recreational water
shortages. What are the reasons for this? What general measures of
water management can be implemented to help mitigate the water shortage
problem?
8. In order to answer the question "Is our tap water safe to drink?" what
word(s) would you have to clarify, what factors related to safety would
you have to consider, and what data would you need as evidence? Discuss.
15-E
WORKING WITH NUMBERS AND GRAPHS
1. Using information from Fig. 15.1 in your text, and from other sources (e.g.
physical geography or hydrology textbooks) in the library, complete the
following table:
Amount in millions
of cubic meters
Amount as % of
earth's stocks of
water*
Amount as % of
earth's stocks of
fresh water
Icesheets/glaciers
Groundwater
Rivers/lakes
Soil moisture
Atm. water vapor
* Earth's stocks of water are taken to be 1.38 x 1018 m3 .
As one can see from figures in the table, the amount of water residing in
the atmosphere (and hence the amount of water involved in the hydrologic
cycle) is minuscule when compared to the amounts of water stocked
elsewhere; yet it is water from the hydrologic cycle that is the key
element in the longer-term water supply equation in most geographic
areas. Why?
2. (a)Review the principle of mass balance (cf. Q.2 in 3-D), as it relates to
geophysical systems. What central concept does it invoke?
(b)Write a mass balance (word) equation in precipitation, evapotranspiration, and runoff for the hydrologic cycle on earth. Ditto for
the hydrologic cycle on the continents. Ditto for the hydrologic
cycle on the oceans.
(c)Contrast the physical quantities that appear on the left (or right)
Page 109
sides of the three equations.
Why are they not all the same?
3. The flow velocity v, in mm/s, of groundwater can be approximated by the
formula (Darcy's Law)
v = K x S
where K = permeability coefficient, in mm/s, of the aquifer material, and
S = slope of the water table (in ratios like 1/200).
Apply the formula to a gravel-and-sand aquifer with a K value of 5 mm/s and
a water table slope of 1/100. What approximate flow velocity do you get?
At this rate, how long would it take the groundwater in the aquifer to
travel a distance of, say, 100 km? What are the ramifications of this
kind of time scales for groundwater pollution?
4. The detention time of a lake may be loosely interpreted as the time it
requires to drain itself at current average rates of outflow, in the
absence of further inflow. Numerically it is given by:
t = V / Q
where t is the detention time (say, in years)
V is the volume of water in the lake (say, in m3 ), and
Q is the average outflow rate (say, in m3 /yr).
Given the following data, find the detention times for Lake Erie and Lake
Ontario.
Lake Erie:
V = 450 km3 ;
Q = 187 km3 /yr
3
Lake Ontario: V = 1570 km ; Q = 210 km3 /yr
Which of these two lakes has a longer detention time? In general, what
does a longer detention time imply for the buildup of pollutants in a
lake? Or for the discharge of pollutants from a lake?
Page 110
Chapter 15
Answers and Solutions
15-A
T: Q.4, 6, 7, 8, 9, 11
F: Q.1, 2, 3, 5, 10
Q.1
tens of times as much as
Q.2
toilets, lawns and bathing
Q.3
for about 10 days
Q.5
the ocean
Q.10 one-quarter
15-B
1b
2f
3a
4d
5h
6i
7e
15-C
1a
2b
3c
4d
5c
6c
7b
8c
9c
10a
15-D
1. (a)Heat capacity: Highest of all common liquids. Bodies of water act as
heat sources or heat sinks, moderating temperature extremes on land.
(b)Latent heats of fusion and vaporization: Highest of all common
substances. Heat released in condensation serves as a major source
of energy for driving water and air movements.
(c)Solubility: One of the best solvents available. Lakes and oceans act
as world's ultimate waste receptacles.
(d)Density: Freshwater exhibits a density anomaly in the 0-4o C range. With
temperatures generally no colder than 4o C, subsurface waters (of
large lakes) in the winter do not freeze, providing more favorable
environmental conditions for aquatic life during that time of year.
2. (a)Aquifer: A rock layer that has substantial amounts of water stored
within its structure and that allows water movement within its
structure. Groundwater is the water stored in aquifers.
(b)i) Rock layers at top/bottom: Confined aquifers are bounded by
impermeable layers above and below, whereas unconfined aquifers have
permeable layers at the upper boundary and impermeable layers at the
lower boundary.
ii) Recharge areas: For confined aquifers the recharge areas are
localized and some distances away. For unconfined aquifers, the
recharge areas lie directly above them.
iii) Water pressure: Greater than atmospheric pressure in confined
aquifers; equal to atmospheric pressure in unconfined aquifers.
(c)Pollution in recharge areas have affected groundwater quality. Soil
compaction, deforestation, etc. in recharge areas have affected the
recharge rate. Overdraft has affected the available quantity.
Corrective measures lie in removing the basic causes.
3. Water withdrawn = Water consumed + Water returned
4. It offers some interesting potentials, but problems include
- very slow recharge rates in most cases (so much so groundwater should
essentially be regarded as nonrenewable);
- vulnerability to contamination by pollutants (and once contaminants are
Page 111
there, they tend to affect the groundwater quality in the area for
decades or even centuries);
- problems of subsidence, water table lowering, and saltwater intrusion
related to groundwater exploitation.
5.
Pollutant category
Key indicator
Units of
measurement
Main sources
Organic wastes
BOD
mg/L
Raw sewage,
food processing effluent
Pathogenic
organisms
Coliform
count
# of E. coli
per 100 mL
Raw sewage,
livestock
waste
Plant nutrients
Phosphorus
ppm
Farmland runoff, municipal
sewage
Toxic chemicals
PCBs, lead,
mercury ...
ppm, ppb ...
Industrial and
mining
effluents
Waste heat
Water
temperature
o
Electric
power plants
C
6.
Type of
treatment
Principle
involved
Types of pollutant
removed by treatment
Types of pollutant
remaining after treatment
Primary
Physical
(filtration
& settling)
and chemical
(chlorination)
Suspended solids,
some BOD and
pathogens
All other contaminants
Secondary
Biological
Remaining BOD and
suspended solids
All other contaminants
Tertiary
Chemical/
Biological/
Physical
Often phosphates and
nitrates, plus
further reductions in
remaining BOD and
suspended solids
All other contaminants
7. Major reasons: Population increases, economic growth, water pollution,
urbanization, poor water resources management.
Mitigating measures: Water conservation, proper watershed management,
water pollution control, stabilization of population
Page 112
sizes.
8. The word safe must be clearly defined, like on what time frame, for whom
("average" person, seniors, pregnant women...), to what extent (one in a
million, one in ten thousand...), with reference to what health parameter
(genetic effects, nervous system damage, cancer causing...), and so on.
You would need comprehensive field data, historical data, and lab data as
evidence, and even then the evidence would not be absolute because all
you could find is a link, not a direct cause-effect relationship.
15-E
1.
Amount in millions
of cubic meters
Amount as % of
earth's stocks of
water*
Amount as % of
earth's stocks of
fresh water
Icesheets/glaciers
2.6 x 1010
1.9
79
Groundwater
6.9 x 109
0.5
21
Rivers/lakes
2.8 x 108
0.02
0.85
Soil moisture
1.4 x 108
0.01
0.42
Atm. water vapor
1.4 x 107
0.001
0.04
* Earth's stocks of water are taken as 1.38 x 1018 m3
The above percentage figures don't add up to 100% because of rounding.
While the amount of water residing in the atmosphere at any one time is
very small, its importance to us lies in the fact that it is renewable
and its replacement rate is fast (short cycling time). Therefore, as a
source of water supply, it is more important than groundwater, even
though stocks of the latter are much larger.
2. (a) (Mass in) = (Mass out)
for steady-state systems
(b) Earth:
(Global) P = (Global) E
Continents:
P (over land) = E (from continents) + R (from land)
Oceans:
P (over oceans) + R (from land) = E (from oceans)
where P is precipitation, E is evaporation or
evapotranspiration,
and R is runoff.
(c) No. What's "mass in" for one system may be "mass out" for another
system.
3. v = 5 mm/s x 1/100 = 0.05 mm/s = 1576800 mm/yr = 1600 m/yr
To move a distance of 100 km, it would take a parcel of the groundwater
over 60 years. This kind of movement rates simply mean that once
contaminants get into the groundwater in an area, they will remain in
that area for a long time.
4. Lake Erie: t = 450 km3 / (187 km3 yr-1 ) = 2.4 years (approx.)
Lake Ontario: t = 1570 km3 / (210 km3 yr-1 ) = 7.5 years (approx.)
Page 113
Lakes with short detention times tend to be polluted quickly, but by the
same token, they also tend to clean themselves up quickly once the
pollution is stopped. The reverse is true of lakes with long detention
times.
Page 114
Chapter 16
16-A
Risk and Cost: Elements of Decision Making
TRUE-FALSE QUESTIONS
Where "F" is your answer, change the underlined portion (and the underlined
portion only) of the statement to make it true.
1.Giving the probability as 0.0001 is the same as saying that the probability
is one in 100,000.
2.A probability of 0.5 means that there will be exactly 50 occurrences out of
100 events.
3.In risk assessment, the public tends to overestimate the risks associated
with jobs and voluntary activities.
4.A lifetime risk of death of one in a million implies that the life
expectancy at birth (assumed here to be 75 years) would be shortened by
about 40 minutes.
5.Implementing a 99% reduction of a pollutant's health risk as opposed to 90%
is likely to increase the cost of control by an extra 9%.
6.Risk analysis is part science and part art.
7.If your area had a "50-year flood" earlier this year, then the probability
of your area being hit with another 50-year flood next year is
theoretically zero.
8.A carcinogen is a substance or agent that causes cancer or promotes the
development of cancer.
9.Risk analysis is a discipline that has come to the fore only in the past 20
years.
10.A statement like "The odds of men developing prostate cancer are one in
twelve" is ambiguous in that it does not give the period over which the
risk applies.
11. Lifetime risks always refer to incidence risks (e.g. the probability of
getting cancer in an entire lifetime), not mortality risks.
16-B
MATCHING QUESTIONS
Match each of Q.1-7 with the most appropriate item from the following list.
Any item in the list may be used more than once, or not at all.
a. mutagen
b. carcinogen
c. teratogen
d. epidemiological studies
e.
toxicological studies
f. risk of nuclear power
g. risk of chemical
plant accidents
h. the 1989 Alar scare
i. risk of indoor air
pollution
1.The experts rate this risk much higher than the public does.
Page 115
2.The experts rate this risk much lower than the public does.
3.It led to apples and apple products being banned from many American school
cafeterias for a while.
4.An agent that causes birth defects.
5.An agent that causes mutations.
6.They often involve testing high doses of toxic chemicals on animals.
7.They cannot prove cause-effect relationships, but do indicate possible
links between environmental factors and their health effects on
populations.
16-C
MULTIPLE-CHOICE QUESTIONS
1.The tragedy of the commons refers to
a. over-exploitation of common
natural resources
b. people's preoccupation with short-term gains
c. a and b
d. none of the above
2.The EPA ranks which of the following as a major public health hazard?
a. Chemical spills in factories.
b. Indoor air pollution.
c. Oil tanker
spills.
d. Water pollution in estuaries.
3.The EPA's four-step process of risk assessment includes all of the
following EXCEPT
a. risk characterization.
b. risk communication.
c. risk identification.
d. dose-response assessment.
4. Sustainable as used in the term "sustainable development" refers to a form
of development characterized by
a. no economic growth.
b. a lowerthan-current rate of economic growth.
c. negative economic growth.
d.
using our resources in a manner that meets the needs of the present
without compromising the ability of future generations to meet their
needs.
5.Which of the following is the lifetime activity that causes the most
cancers in North America today?
a. Eating processed food that contains
additives.
b. Drinking public supply water that is contaminated.
c. Breathing polluted air indoors and outdoors.
d. Smoking
6.Today some chemicals can be measured in concentrations as low as
a. parts per quadrillion.
b. parts per million.
c. parts per billion.
d. parts per trillion.
7.When the simultaneous exposure to two toxic substances results in a
combined effect that is greater than the sum of the separate effects, the
phenomenon is referred to as
a. compound toxicity.
b. synergism.
c. biomagnification.
d. carcinogenesis.
8.Environmental cost-benefit analysis involves all of the following
Page 116
problematic aspects EXCEPT
a. assigning specific dollar values to the
intangibles.
b. whether to consider the costs and benefits on a longterm or short-term basis.
c. our inability to quantify the risks
precisely.
d. identifying the project to be evaluated.
9.As used in the Issues and Analysis (Shrimp and Turtles) box of this
chapter, TED stands for the
a. turtle excluder device.
b. toxic
environment database.
c. tidal energy development.
d. turtle
exclusion design.
10. The Tragedy of the Commons was written by
a. Rachel Carson.
Ehrlich.
c. Garrett Hardin.
d. a Greenpeace researcher.
16-D
b. Paul
QUESTIONS FOR REVIEW, RESEARCH AND CRITICAL THINKING
1. Distinguish between risk assessment and risk management. What are the
elements of each? In the literature, you may also encounter the term
risk analysis. What does it mean to you? How are the three terms
related?
2. Refer to Fig. 16.4. Suggest some reasons why, in assessing and ranking
risks, significant disparities often exist between
scientists/professionals and lay people?
3. Summarize The Tragedy of the Commons (Global Perspective) in one sentence.
4. In your daily life, how do you decide whether or not to take a risk?
factors do you normally take into consideration?
What
5. List a few controversial aspects of toxicity studies based on dose-response
data obtained with animals in the laboratory.
16-E
WORKING WITH NUMBERS AND GRAPHS
1. (a)What are some common ways to express risk probabilities?
(b)Suppose the lifetime risk of death in an automobile accident is 0.02,
and of dying of different forms of cancer is 0.22. What would be
the combined lifetime risk of one becoming either an auto death
victim or a cancer death victim?
2. Refer to Fig. 16.2.
(a)If you ate Pacific Cod (first column, ninth item from the top) one meal
a week during your entire life, what would be your lifetime cancer
(incidence) risk, as a direct result of eating Pacific Cod,
according to the chart?
(b)For a population of 3 million (assuming everybody else also ate Pacific
Cod as you did), how many new cases of cancer (as caused by eating
Pacific Cod alone) might be expected per year?
3. Refer to Fig. 16.3, and use swimming as an example.
Page 117
(a)What is the risk of death from drowning for every 1000 hours of
swimming, according to the chart?
(b)Express the risk of drowning as lifetime risk for an individual
(assuming that the average person lives 75 years and swims 10 hours
per year).
(c)How many cases of drowning per year might be expected for a population
of 30 million?
4. Suppose a test for a rare disease, which affects one out of every 10,000
people in the population, is accurate 99.99% of the time. If someone
tests positive, what is the probability that his/her positive result is a
false one?
5. A recent Canadian study on breast cancer revealed the following statistics:
Age
Birth
20
25
30
35
40
45
50
55
60
65
70
75
80
85
Probability of developing breast cancer
within next year
within 5 years
0.00%
0.00
0.00
0.02
0.04
0.08
0.14
0.18
0.20
0.24
0.28
0.31
0.34
0.34
0.36
0.00%
0.00
0.04
0.15
0.26
0.48
0.78
0.92
1.06
1.29
1.43
1.54
1.59
1.55
1.52
(a)According to the data, what is the probability of a 40-year old woman
developing breast cancer within the next year? And within the next
five years? What are those probabilities when expressed in "within
that particular age group, one woman in so many will contract breast
cancer within the next year (or within the next five years)"?
(b)It is sometimes said that one Canadian woman in nine will contract
breast cancer sometime during her lifetime. Is there sufficient
data in the table to allow you to arrive at more or less the same
conclusion? Elucidate.
(c)Why are statements like "One Canadian woman in nine will develop breast
cancer" misleading? Explain.
6. If one source tells you that in a given year (say 1988), there were 49,000
automobile deaths in the country, and another source says that the
lifetime risk of death in an automobile accident for that same year was
0.02, what simple calculations can you perform to ascertain whether or
not the two sources of information are stating essentially the same fact?
(Note: The population is assumed to be 235 million. In addition, you
Page 118
would have to make a reasonable assumption about the life expectancy in
the country.) Show your work.
7. The dose-response equation for a carcinogen is given as (see, for example,
G. M. Masters, Introduction to Environmental Science and Engineering,
Prentice-Hall, 1991):
Lifetime risk = (Average daily dose) x (Potency factor), where
lifetime risk is the probability of developing cancer in a lifetime,
average daily dose is in mg of chemical/kg of body weight/day, and
potency factor is a measure of the "strength" of the chemical, expressed
in (mg of chemical/kg of body weight/day)-1 , as determined by
toxicologists.
Apply the above formula to a situation where you want the lifetime risk to
be no more than one in 100,000, and where the chemical under
consideration (say, dioxin) has a potency factor of 1.56 x 105
(mg/kg/day)-1 . What would be the maximum allowable daily dose of the
chemical for a man 70 kg in weight?
Page 119
Chapter 16
Answers and Solutions
16-A
T: Q.4, 6, 8, 9, 10
F: Q.1, 2, 3, 5, 7, 11
Q.1
one in 10,000
Q.2
approximately 50 occurrences out of 100 events
Q.3
underestimate
Q.5
much more than an extra 9%
Q.7
remains 1/50
Q.11 may refer to incidence risks or mortality risks
16-B
1i
2g
3h
4c
5a
6e
7d
16-C
1c
2b
3b
4d
5d
6a
7b
8d
9a
10c
16-D
1. Risk assessment is the determination of the probability of harm from
exposure to a hazard. Elements of risk assessment include the
identification of the risk, field observations and/or laboratory studies
linking the harm to the exposure, and numerical characterization (i.e.
calculation of the probability) of the risk.
Risk management is the use of options and strategies to deal with the risk.
It uses risk-reward or cost-benefit analysis to help make decisions.
Risk analysis is used by some as a general term that includes both risk
assessment and risk management.
2. Knowledge - or lack of it - of the risk is one main factor. Psychology is
another. Lay people tend to overestimate risks that are catastrophic,
imposed on them, related to exotic technology, etc., and underestimate
risks that are voluntary, natural, associated with familiar situations,
etc.
3. People tend to abuse common resources for their short-term gain.
4. Risk assessment: Consider both the probability of the risk and the
consequences of the risk.
Risk management: Consider risk/reward ratios to determine whether to
take the risk or eliminate or reduce the risk. If you choose to
eliminate or reduce the risk, then consider various options.
5. a. High dosages used in labs do not represent low-level chronic exposures
in the real world. Extrapolated results are highly controversial.
b. Findings based on testing animals may not apply to humans.
c. Statistical "noise" may overwhelm the signal we want to detect.
16-E
1. (a)Expressed as decimals (e.g. 0.04), as % (e.g. 4%), or as fractions
(e.g. one in 25).
(b)Combined risk = 0.02 + 0.22 - (0.02)(0.22) = 0.2356 = 24%
Page 120
2. (a)P = 6 x 10-4 = 6/10000 = 1/1700
(b)Number of cancer cases for the entire population in a lifetime is:
(3 x 106 ) (6 x 10-4 ) = 1800
If we assume that those 1800 cases of cancer are spread out over a 75year period, then
No. of new cancer cases per year = 1800/75 = 24
3. (a)According to the chart, there are 2560 deaths per 109 (the chart's
figure is actually 106 , but that seems to be an error) hours of
swimming, which is the same as saying there is 0.00256 death per
1000 hr of swimming, or there is a 0.26% chance of death per 1000 hr
of swimming.
(b)We assume that in one lifetime, there are
75 x 10 = 750 hours of swimming
Then x : 750 = 0.26% : 1000,
or
x = 0.192% = 0.19%
(c)In one year, 30 million people will do 300 million hours of swimming,
which translates into
(300 x 106 hr) (0.00256 death/1000 hr) = 768 deaths per year
4. Let's use a hypothetical population size of 1,000,000 for illustration
purposes. Out of this population, there will be:
999,900 people who do not have the disease, and
100 people who are afflicted with the disease.
Testing the 999,900 healthy people will give 100 false positives (i.e.
0.0001 x 999,900), and testing the 100 sick people will give 100 true
positives. In other words, out of a total of 200 positives, 100 are
false ones. The probability therefore is 0.5.
5. (a)The probability is 0.08% (or 8/10000, or one in 1250) within the next
year; and 0.48% (or 48/10000, or about one in 210) within the next
five years.
(b)No, because you would also need to know the number of women in each age
group (i.e. No. of women x probability = new cancer cases in that
age group) for a hypothetical cohort of 1000, say. However, a rough
estimate of the lifetime risk can be obtained by summing the
probabilities in the "within 5 years" column. When those percent
figures are added up, the result is 12.61%, which corresponds to a
1 : 7.8 ratio.
(c)Such statements are misleading because the risks referred to are
actually spread out over an entire lifetime. Using the breast
cancer statement as a case in point, people might be alarmed by the
"high rate" when, in fact, for women in their early forties, only
about one in 210 will develop breast cancer within the next five
years.
6. If the lifetime risk of death in an auto accident is 0.02, and assuming an
average lifetime to be 75 years, then 0.02/75 yr is equivalent to
0.000267/yr. For a population of 235 million, the number of auto deaths
is given by
235 million x 0.000267/yr = 62745 per yr
Page 121
This compares with 49,000 deaths per year as given by the other source.
The two figures are not in complete agreement, but could still be
referring to essentially the same probability. The discrepancy could be
due to the fact that only one significant digit was given for the
probability (0.02) of the risk.
7. If we let d represent the average daily dose, then
1/100000 = d (1.56) (105 ) (kg of wt-day/mg of dioxin)
or
d = (1/1.56) (10-10) (mg of dioxin/kg of wt-day)
or
d = 6.4 x 10-11 (mg of dioxin/kg of wt-day).
For a 70-kg man then, the maximum average daily dose must not exceed
d = 6.4 x 10-11 (mg of dioxin/kg of wt-day) (70 kg)
= 4.5 x 10-10 (mg of dioxin/day).
Page 122
Chapter 17
17-A
Air Pollution
TRUE-FALSE QUESTIONS
Where "F" is your answer, change the underlined portion (and the underlined
portion only) of the statement to make it true.
1.In chemical makeup, the ozone that protects us from harmful UV radiation is
entirely different from the ozone that contributes to photochemical smog.
2. Particulates are small pieces of solid materials, such as dust, ash and
bits of asbestos, that are dispersed into the atmosphere as pollutants.
3.Though not precisely defined, acid rain is normally taken to mean
precipitation that has a pH less than 7.
4.The burning of fossil fuels is the single largest source of air pollutants
in North America.
5.In North America, the last ten years have seen meaningful reductions in all
major types of primary air pollutants except sulfur dioxide.
6.Currently, about half of the air pollutants contributing to acid deposition
in eastern Canada originate from sources in the US.
7.The most abundant and most important greenhouse gas is CFCs.
8.For the same air pollutants, indoor concentration levels are generally
higher than outdoor concentration levels.
9.In Canada, land east of Manitoba generally has a low tolerance for acid
deposition.
17-B
MATCHING QUESTIONS
Match each of Q.1-7 with the most appropriate item from the following list.
Any item in the list may be used more than once, or not at all.
a. ambient air quality
b. Canada's National Air Quality Objectives
c.
stratospheric ozone-depleting chemicals
d. SBS (Sick Building Syndrome)
e. atmospheric turbulence and instability
f. ground-level ozone
g.
CO2
h. CO
1.An ozone layer that is in the wrong place.
2.They are based on a 3-tier system: desirable, acceptable and tolerable.
3.Conditions that are conducive to air pollutant mixing and dispersal.
4.Outdoor air quality.
5.Chemicals like CFCs and carbon tetrachloride.
6.Ailments caused by air pollutants in a building where people work or live.
Page 123
7.Though not a primary outdoor air pollutant, it is a major greenhouse gas.
17-C
MULTIPLE-CHOICE QUESTIONS
1.All of the following are primary outdoor air pollutants EXCEPT
a. carbon monoxide.
b. sulfur dioxide.
c. hydrocarbons.
d. photochemical oxidants.
2.Scrubbers have been installed by power plants and smelters to remove
primarily
from smokestack emissions.
a. lead and other metals
b. hydrocarbons
c. sulfur oxides
d. particulates
3.What is necessary in addition to the chemicals for a secondary pollutant to
form?
a. Water.
b. Particulates to provide centers of deposition.
c. Sunlight.
d. Acids to activate the chemical reactions.
4.Sulfur dioxide has all of the following characteristics EXCEPT
a.
a sharp odor.
b. reaction with water.
c. irritation of lung tissue.
d. ability to trap heat.
5.Common indoor air pollutants in North America include
a. asbestos and
formaldehyde.
b. volatile organics and tobacco smoke.
c. dust and
mold. d. all of these.
6.Photochemical smog is characteristic of urban areas with many motor
vehicles and a climate that is
a. cool, wet and cloudy.
b. cool, dry
and sunny.
c. warm, dry and sunny.
d. warm, wet and cloudy.
7.All of the following are secondary air pollutants EXCEPT
a. ground-level
ozone.
b. sulfuric acid.
c. peroxyacetylnitrates (PANs).
d.
carbon monoxide.
8.Which of the following statements about a temperature (thermal) inversion
is false?
a. It aggravates ground-level air pollution.
b. It is an
atmospheric condition that is not conducive to the vertical mixing of air
pollutants.
c. It is more likely to occur in a city surrounded by hills
or mountains.
d. It is an atmospheric condition where cooler air lies
above warmer air.
9.In Canada, smog alerts are issued when ground-level ozone levels exceed
a. 82 ppb.
b. 125 ppb.
c. 30 ppm.
d. 57 ppm.
10.Increased UV radiation at the earth's surface will most likely cause higher
incidence rates of
a. skin cancers.
b. eye cataracts.
c.
heart attacks.
d. a and b but not c.
11.Which of the following cities is most likely to have the cleanest outdoor
air?
a. Vancouver.
b. Calgary.
c. Windsor.
d. Montreal.
12.Acid rain in an area can owe its acidity to
Page 124
in the atmosphere.
a. carbon dioxide
these
b. sulfur dioxide
c. nitrogen dioxide
d. all of
13.Which of the following statements about photochemical smog is NOT true?
a. Smog is just another name for ground-level ozone.
b. Smog tends to
occur on days with temperature inversions.
c. Smog is made up of a
number of secondary air pollutants known as photochemical oxidants.
d. oxides of nitrogen and hydrocarbons are the major pollutants
contributing to smog.
14.Which of the following regions in Canada generally have the highest
buffering capacity for acid deposition?
a. The southern parts of the
prairie provinces.
b. Quebec and southeastern Ontario.
c. The coastal
regions of southern B.C.
d. The maritime provinces.
15.Fish populations in acid lakes begin to decline when the pH of the water
falls below
a. 7.
b. 6.
c. 5.
d. 4.
17-D
QUESTIONS FOR REVIEW, RESEARCH AND CRITICAL THINKING
1. Add three columns to Table 17.1, labeling them respectively "Human health
and/or other effects," "Concentration level trend, 1985-95," and "Control
strategies." Then complete the table for each of the pollutants listed.
2. Distinguish between brown-air cities and gray-air cities.
examples of each for Canada.
Give two
3. Using resources available in the library, answer the following questions on
catalytic converters (with which today's automobiles are equipped):
(a)What are used as the catalysts? What purpose do they serve?
(b)What three types of pollutants in exhaust gases are being converted?
And into what "harmless products" are they being converted?
(c)What approximate % reductions in tailpipe emissions can be achieved
with catalytic converters in new cars in the mid-1990s (compared to
cars in the late 1960s)?
(d)The catalytic converter has been hailed by some as a technological
breakthrough in solving tailpipe emissions problems, but has it
largely eliminated air pollution from tailpipe emissions so far? If
not, why not? Justify your answer with numerical estimates.
4. (a)Name the two major air pollutants responsible for acid deposition. For
each of these pollutants, write a word equation describing the basic
chemical changes involved.
(b)What are the two major industries that produce these air pollutants in
North America?
(c)Generally speaking, has there been any success in reducing acid
deposition in North America in the last ten years? Quote figures to
demonstrate the extent of the improvement, if any. What measures or
devices have been instrumental in bringing about the improvement, if
any?
(d)It has been estimated that half of the acid deposition in Canada
Page 125
originates in the US. What processes are responsible for this?
Wouldn't the same processes also deposit much of Canada's acidforming pollutants in the US? Explain.
5. Explain why the degree of the impact of acid deposition on a given lake
should be related to the four factors shown in Fig. 17.12. What
significant factors other than the aforementioned four can you think of
that would also affect the impact? Elaborate.
6. (a)List 6-8 common air pollutants in the home and in the workplace today.
Where are these pollutants coming from? What energy-conserving
practices in recent years have aggravated the indoor air pollution
problem?
(b)Are we dealing with the same air pollutants in our indoor environment
as in our outdoor environment? Name three air pollutants that are
common to both environments, and another three that generally pose
problems only in the indoor environment.
(c)Just how "good" or how "bad" do you think indoor air quality is in
North America's major cities today? Quote estimates or statistics
to support your view.
(d)Considering the fact that we spend some 90% of our time indoors, do you
believe that the issue of indoor air pollution (if it is a problem)
warrants more attention and action than it has received so far?
Comment.
7. (a)What are the telltale signs of the sick-building syndrome (SBS)?
(b)What simple actions can you take to reduce the risks of indoor air
pollution?
8. (a)Distinguish between ground-level ozone and stratospheric ozone.
(b)For what reasons, human health or otherwise, have higher concentrations
of ground-level ozone become a major environmental concern today?
Name three.
(c)Similarly, for what reasons have the lower concentrations of
stratospheric ozone become a major environmental concern today?
Name three.
9. (a)When referring to ultraviolet radiation, people sometimes speak of UV-A
and UV-B. What is the difference? Biologically speaking, which is
the more harmful radiation?
(b)What precautions can you take to protect yourself from the risks of
ultraviolet radiation outdoors?
17-E
WORKING WITH NUMBERS AND GRAPHS
1. (a)Distinguish between high-sulfur coal and low-sulfur coal. Both the US
and Canada have large coal reserves. Are coals from these reserves
mostly high or low in sulfur content?
(b)If the annual coal consumption in Canada is 45 million tonnes, about
how many tonnes of sulfur dioxide would be produced each year from
the combustion of coal alone, with no emission controls? And with
existing emission controls? Give your assumptions and reasoning.
Page 126
2. Differentiate between parts per million by weight and parts per million by
volume. Which of the two is temperature-independent? Which of the two
is being referred to when gaseous air pollutant concentrations (e.g. 25
ppm of carbon monoxide) are given? And when water pollutant
concentrations (e.g. 0.1 ppm of zinc in lake water) are given?
3. Air pollutant concentrations are often given in units of ppm or units of
:g/m3 . The conversion between these two sets of units is given by (for an
assumed air temperature of 250 C):
(Conc. in ppm) = (Conc. in :g/m3 ) (0.02445) ) (Molecular wt. of gas)
If the concentration level of nitrogen dioxide (NO2 ) at a certain location
is 0.053 ppm, find its equivalent in :g/m3 .
4. According to Canada's National Ambient Air Quality Objectives (1989), the
maximum desirable concentrations for carbon monoxide, for example, are
respectively
Q 5 ppm on an 8-hour averaging time basis, and
Q 13 ppm on a one-hour averaging time basis.
Explain why for the same air pollutant, the standard should be different
when the averaging time period is different.
5. Complete the following table:
Greenhouse gas
Annual
concentration
increase (%)
As % of
greenhouse
contribution
Principal sources
Carbon dioxide
CFCs
Methane
Tropospheric O3
Nitrous oxide
6. Using information from your local newspaper or weather service, complete
the following table for a downtown area of your city for a mid-August
week (Mon.-Fri. only) last summer:
Date
Air pollution index at 4 p.m.
Page 127
UV index at noon
For the five days under consideration, were the ambient air pollution
levels generally high, moderate or low according to established
standards? And what about the UV levels?
Page 128
Chapter 17
Answers and Solutions
17-A
T: Q.2, 4, 6, 8, 9
F: Q.1, 3, 5, 7
Q.1
the same as
Q.3
that has a pH less than 5
Q.5
except nitrogen oxides
Q.7
carbon dioxide
17-B
1f
2b
4a
5c
6d
7g
17-C
1d
13a
2c
3c
4d
14a
15b
5d
6c
7b
3e
8d
9a
10d
11b
12d
17-D
1. Human health/other effects
CO:
Health effects range from headaches to asphyxiation
HCs:
Some are carcinogenic; contribute to photochemical smog
Particulates: Contribute to heart and lung problems
SO2 :
Irritates respiratory tract; adds stress to heart;
contributes to acid precipitation
NOx :
Contribute to photochemical smog and acid precipitation
Concentration level trend
All trending downward, with cumulative reductions in the range of 10-40%
in over the 10-year period. The best improvements are found in CO and
SO2 , the least in nitrogen oxides.
Control strategies
a) Energy efficiency and conservation (for all 5 pollutants)
b) Emission controls (e.g. catalytic converters for CO, HCs and NOx ;
scrubbers for SO2 and other gases; precipitators and filters for
particulates)
c) Modifications to combustion process (e.g. adjusting combustion
temperature to reduce NOx production, use of low-sulfur coal to
reduce SO2 production)
d) Development of alternative energy sources
2. Brown air: Photochemical smog; Windsor (Ont.), Toronto (Ont.)
Gray air: Industrial smog; Hamilton (Ont.), Sydney (N.S.)
3. (a) Platinum and palladium. To speed up chemical reactions.
(b)CO, HCs and NOx . CO is converted to CO2 , HCs to water and CO2 , and NOx
to nitrogen.
(c)When car engines have adequately warmed up and are running under normal
conditions: about 98% for CO; 98% for HCs; 90% for NOx .
(d)No, even though the above figures look very impressive on paper. This
is in part due to the fact that more cars are in use and more
kilometers are driven today than twenty/thirty years ago, and in
part attributable to the reality that the older, poorly-maintained
Page 129
cars that are on the road spew out a lot more pollutants than
suggested by the previously cited percentage figures. (Cold starts
and traffic jams also aggravate the problem.)
For some numbers, let's do it for NOx from cars in Canada. First,
published statistics show that the number of cars on the road have
almost doubled since the late 1960s (1967: about 7.6 million; 1997:
about 14.2 million). Second, the average number of kilometers
driven per car per year is probably 35% more today. Third, the
actual NOx reduction rate for the average car on the road today, as
compared to the 1967 level, is probably no higher than 65% (the 90%
figure quoted above would simply be unattainable because of older
and poorly maintained cars, cold starts, traffic conditions, etc.,
as cited above). Now we note that:
(Total amount, in %, of NOx emissions from cars in a year)
= (100% - NOx reduction efficiency) x (Avg. no. of
kilometers driven per car per year) x (No. of cars on road).
For 1967: NOx = (100%) x (1) x (1) = 100% (1967 used as base year)
For 1997: NOx = (35%) x (1.35) x (1.9) = 90% (of 1967 level)
In other words, the amount of nitrogen oxides emitted by cars in 1997
is only marginally lower than that in 1967! These figures indicate
why we cannot rely on catalytic converters alone to solve the air
pollution problem arising from tailpipe emissions.
4. (a)SO2 and NOx .
Sulfur (in fuels) + Oxygen = Sulfur dioxide
Nitrogen (in furnace, combustion chamber) + Oxygen = Nitrogen oxides
(b)SO2 : Base metal smelting and thermoelectric generating stations.
NOx : Transportation and thermoelectric generating stations.
(c)Yes, with regard to SO2 , to the extent of 50% or so reduction, largely
derived from installation of emissions-control devices required by
governments. No, with regard to NOx , since almost half of it comes
from cars and as we have seen in the answer to 3(d) above, benefits
from catalytic converters have been negated by more cars and more
kilometers driven.
(d)Direction of the prevailing wind. No.
5. - Wind direction and pollution source:
Wind transports pollutants to lake located downwind.
- Insoluble hard rock and thin layer of soil:
Land has little buffering capacity for acid deposition, and as a
result inflow into lake is more acidic.
- Soil with low buffering capacity:
Same reason as above.
- Low watershed to lake area ratio:
Acid precipitation does not have enough time/area to interact with soil
buffers before entering the lake.
- Other factors include:
Q Type of trees in the area (evergreens tend to intensify acidity)
Q Landform in the area (steep slopes do not give soils enough time
to interact with runoff)
Q Permeability of the soil
Q Type of fuel used by industry in the area
Page 130
6. (a)Asbestos, carbon monoxide, formaldehyde, mold spores, nitrogen dioxide,
ozone, particulates, radon, volatile organics, among others.
Principally the combustion of fuels, the vapors from construction
materials and furnishings, and human activities (e.g. smoking, use
of xerox machines and oven cleaners...) in the indoor environment.
The problem is being aggravated by poor ventilation and air-tight
building construction in recent years.
(b)In some cases yes, in other cases no.
Common to both indoor and outdoor environments:
CO, particulates, NOx
Generally indoor environment only:
Molds, radon, asbestos
(c)By some estimates about 20% of the houses/buildings in North American
cities have unacceptable air qualities.
(d)Yes, indoor air pollution is a major pollution problem and warrants
more attention. It is unfortunate that most lay people do not see
it as such.
7. (a)If several people in the same building have the same symptoms, and if
those symptoms disappear when the people are elsewhere.
Also people have to be wary when they move into a house/building right
after construction/renovation, when the building has an odor
problem, or when the ventilation system of the building doesn't seem
to be working properly.
(b)- Make sure the ventilation system/furnace/fireplace is working
properly
- Keep decor simple and house clean
Open windows periodically
Avoid storing chemicals indoors
No smoking indoors
Exercise caution when using volatile organics indoors
8. (a) Ground-level ozone: Ozone that is found in the bottom parts of the
troposphere (hence also called tropospheric ozone). There is
naturally-occurring ground-level ozone, but when we use the term, we
are mostly thinking of the ground-level ozone (a secondary air
pollutant) produced by human activities. It is harmful to humans
and plants.
Stratospheric ozone: Naturally-occurring ozone that is found in the
stratosphere, particularly at 25-40 km above the earth. It blocks
most of the UV-B (the biologically harmful component) from reaching
the earth's surface.
(b)- Lungs susceptible to ozone damage
- Breathing problems and heart attacks for people with respiratory
illnesses
- Eye, nose and throat irritation among healthy individuals
- Damage to vegetation
(c)- More skin cancers and cataracts because of higher levels of UV-B
- Suppression of the immune system
- Damage to crops
9. (a) UV-A is the longer-wavelength component (band) of the UV radiation.
Most of the extraterrestrial UV-A reaches the earth's surface
Page 131
unattenuated (as stratospheric ozone cannot block it), but
fortunately for us, UV-A is considered to be not much harmful, if
harmful at all (though this theory has been challenged by some
researchers in recent years).
UV-B is the shorter-wavelength component of the UV radiation. Only
between 1-10% of the extraterrestrial UV-B reaches the earth's
surface. It is believed to be much more harmful than UV-A, and has
been linked to skin cancers, cataracts and disruption of the immune
system.
(b)Avoid direct exposure to sunlight between 9 a.m. and 3 p.m (10 a.m. and
4 p.m. daylight saving time). If you do engage in outdoor
activities between those hours, wear protective clothing and a
sunscreen of at least SPF 15.
17-E
1. (a)The terms have not been precisely defined, but generally taken to mean
> 1% (by weight) of sulfur for high-sulfur coal,and
< 1% (by weight) of sulfur for low-sulfur coal.
Coals from western Canada and western US are generally low-sulfur
coals. Coals from eastern Canada and eastern US are generally highsulfur coals.
(b)With no emissions controls, and assuming a 2.0% sulfur content,
Amount of sulfur from coal = 45 million tonnes x 0.020
= 0.90 million tonnes (of S per yr)
Amount of SO2 produced = 0.90 million tonnes (of S)
+ 0.90 million tonnes (of O2 )
= 1.80 million tonnes (of SO2 per yr)
With emissions controls, and assuming a 70% efficiency, the amount of
sulfur dioxide produced would amount to about 0.54 million tonnes
per year.
2. See also answer to Q.3 in 1-E. The units of ppm by weight, generally used
in water pollution work, refer to "so many mg of the contaminant per
liter of the liquid mixture." Loosely, it can be considered as being
equivalent to "so many mg of the contaminant per 1,000,000 mg of the
liquid mixture." The units of ppm by volume, often used in air pollution
work, refer to "so many volumes of the gaseous pollutant per 1,000,000
volumes of the polluted air." These units are temperature-independent.
Finally,
25 ppm of CO refer to ppm by volume,
0.1 ppm of zinc in lake water refers to ppm by weight.
3. If we use C to represent the concentration of NO2 in micrograms/m3
then
0.053 = C (0.02445/46)
or
C = 99.7 micrograms of NO2 per cubic meter of air
4. Here we note that a lower concentration of CO goes with a longer averagingtime base, and vice versa. This is what we would expect intuitively on
grounds that exposure to low levels of a harmful pollutant for an
extended period of time would produce similar health effects as exposure
to higher levels of the same pollutant for a short period of time.
Page 132
5.
Greenhouse gas
Annual
concentration
increase (%)
Carbon dioxide
As % of
greenhouse
contribution
Principal sources
0.4
55
Fossil fuels,
deforestation
Being phased out
20
Foams, refrigerants
Methane
0.5
15
Wetlands, livestock,
insects
Tropospheric O3
0.5
5
Fossil fuels
Nitrous oxide
0.2
5
Fertilizers, fossil
fuels
CFCs
6. Answers will vary.
Page 133
Chapter 18
18-A
Solid Waste Management
TRUE-FALSE QUESTIONS
Where "F" is your answer, change the underlined portion (and the underlined
portion only) of the statement to make it true.
1.In terms of either weight or volume, municipal solid waste constitutes a
major fraction of Canada's total solid waste stream.
2. Landfilling is still by far the most common and most important method of
municipal solid waste disposal in Canada today.
3.At present, most Canadian landfills are closer to the state-of-the-art
landfill than to the rudimentary dump.
4.The "4 Rs of waste management" refer to reduction, reuse, recycling and
repackaging.
5.The current problem of towns and cities running out of landfill space is as
much a reflection of the rapid growth in municipal solid waste production
as the NIMEY syndrome.
6.The Canadian Council of Ministers of the Environment has set a national
goal for per-capita municipal solid waste reduction of 50% by weight
(based on 1988 waste levels) by the year 2000.
7. Until composting and multiple-materials recovery are widely practiced, we
are unlikely to achieve substantial (say, 40-50%) reductions in the
quantity of municipal solid waste produced.
8.In their operation, state-of-the-art MSW incinerators of the 1990s do not
release any toxic pollutants into the atmosphere.
9.One reason incineration of municipal solid wastes is environmentally more
damaging here than in Japan and Europe is that North American wastes
generally contain more plastic and toxic materials.
10.Under ideal conditions, modern solid waste incinerators may reduce waste
volume by as much as 90%, but in practice the actual volume reduction is
closer to about 60%.
18-B
MATCHING QUESTIONS
Match each of Q.1-7 with the most appropriate item from the following list.
Any item in the list may be used more than once, or not at all.
a. MSW
b. mass burn
c. leachate
d. groundwater monitoring well
e.
gas recovery system
f. landfill liner
g. HDPE
h. LDPE
1.It is used in the manufacture of rigid containers like milk jugs.
2.It generally includes residential, commercial and light industrial solid
Page 134
waste.
3.Water samples from it are regularly analyzed for indications of any
possible contamination.
4.Contamination of groundwater by this noxious chemical solution is one of
the biggest hazards from sanitary landfills.
5.This waste-disposal technology works more efficiently in Europe than in
North America.
6.Its purpose is to collect the methane produced within a landfill.
7.It is commonly used to make cellophane wraps and garbage bags.
18-C
MULTIPLE-CHOICE QUESTIONS
1.Which of the following words is closest in meaning to the term municipal
solid waste?
a. Trash.
b. Refuse.
c. Garbage.
d. Rubbish.
2.Municipal solid waste refers to
a. residential solid waste.
waste that goes into municipal landfills and incinerators.
industrial solid waste.
d. commercial solid waste.
b. all the
c. light
3.The largest component (by weight) of North America's municipal solid waste
is
a. paper.
b. food and plant.
c. glass.
d. plastics.
4.In Canada, residential solid waste makes up about
of the total quantity
of municipal solid waste.
a. 1/5
b. 2/5
c. 3/5
d. 4/5
5.The Canadian municipal solid waste production rate (before recycling and/or
composting) is estimated to be in the range of
kg/person/day.
a.
1.5-2.0
b. 2.0-3.0
c. 3.0-5.0
d. 5.0-10.0
6. Landfill gas is primarily
nitrogen.
d. methane.
a. carbon monoxide.
b. carbon dioxide.
7.The underground decomposition of organic matter by
produces methane
that can escape from within the landfill to the air.
a. water and
oxygen
b. anaerobic bacteria
c. aerobic bacteria
d. synthetic
chemicals
8.In terms of percentage by weight,
makes up the bulk of the ash from
solid waste incineration.
a. fly ash
b. stack ash
c. bottom ash
d. mass-burn ash
9.For mass-burn incinerators to combust waste without excessive emission of
air pollutants, they must
a. operate at very high (>900o C)
temperatures.
b. have adequate and well-maintained pollution control
devices.
c. be properly supervised and run by fully-trained
technicians.
d. all of the above.
10.Composting has the theoretical potential of reducing the quantity of
Page 135
c.
municipal solid waste requiring disposal by as much as
b. 20%.
c. 30%.
d. 50%.
a. 10%.
11.Today's sanitary landfills are designed to completely contain their wastes
for at least
a. 10 years.
b. 25 years.
c. 50 years.
d. 100 years.
12.The number of landfills in Canada is
a. decreasing.
b. increasing.
c. staying steady.
d. increasing at the same rate as the population
increase.
13.Which of the following practices is likely to divert the largest amounts of
solid wastes from municipal landfills and incinerators?
a. Recycling
paper and aluminum cans.
b. Recycling glass bottles and aluminum cans.
c. Recycling paper and composting.
d. Recycling plastics and
composting.
14.The management and disposal of scrap tires remain problematic because
a. scrap tires buried in landfills may float.
b. stockpiled scrap tires
may catch fire.
c. few uses have been found for scrap tires.
d. all
of the above.
18-D
QUESTIONS FOR REVIEW, RESEARCH AND CRITICAL THINKING
1. Study Fig.18.3, which shows the different components of municipal solid
waste by weight. With practice of the 3Rs, about how many percent of
this current waste stream do you think could realistically be eliminated
or diverted? At present, about how many percent are being diverted from
landfills or incinerators in those North American cities and towns that
have a recycling and/or other waste management program in place? What
does this figure tell you about North America's success with 3Rs in
general?
2. Do biodegradable products and recyclable packaging materials really help
reduce inputs into the solid waste and wastewater streams? Are such
products/packaging materials really better for the environment?
3. As of mid-1996, some 3000 North American communities have adopted the userpay system for municipal solid waste collection, where households are
charged either by the bag or by weight. Which version of the system,
volume-based or weight-based, is preferred by you, and why?
4. List five to six key criteria for selecting sanitary landfill sites. Of
these criteria, is there one that is perhaps more critical than any
other?
5. A 1996 study conducted for Metropolitan Toronto found that on average, each
tonne of recyclables cost the city approximately $86 (Cdn) to collect and
sort, but generated only about $23 of revenue from the sale of the
recycled materials. Is recycling really a "losing proposition" as some
call it? What is the real cost - or benefit - of recycling from the
economic perspective? And from the environmental perspective? Comment.
Page 136
18-E
WORKING WITH NUMBERS AND GRAPHS
1. Estimate the number of car and truck tires discarded by Canadians each
year. Cite any statistics used or assumptions made in your estimation.
2. By one estimate, approximately 1 ha-m (hectare-meter) of landfill volume is
needed each year to serve every 14,000 urban residents.
(a)About how many kg (of solid waste)/person/day is the above relationship
equivalent to? Assume that compacted municipal solid waste weighs
800 kg/m3 , and that the daily soil cover material adds 25% to the
overall landfill volume.
(b)For a population of 400,000 what would be the anticipated life, in
years, of a landfill that has an area of 50 ha and an average fill
depth of 12 m?
Page 137
Chapter 18
Answers and Solutions
18-A
T: Q.2, 6, 7, 9, 10
F: Q.1, 3, 4, 5, 8
Q.1
only a tiny fraction
Q.3
closer to the rudimentary dump than to the state-of-the-art
landfill
Q.4
reduction, reuse, recycling and recovery
Q.5
NIMBY syndrome
Q.8
still release toxic pollutants into the atmosphere but in amoumts
that normally do not exceed emission standards
18-B
1g
18-C
1c
13c
2a
3d
4c
5b
6e
7h
2b
3a
14d
4b
5a
6d
7b
8c
9d
10c
11b
12a
18-D
1. Answers will vary, but a 50% overall reduction is easily attainable and an
80-90% reduction is not impossible. Currently, even in those areas where
there is a recycling program, only about 25-35% of the solid waste stream
is diverted from landfills or incinerators. The 25-35% figure indicates
that considerable progress has been made (mostly in the recycling of
newspapers and aluminum cans), but much remains to be done in source
reduction (particularly through the use of reduced packaging and
refillable containers), composting and multiple-materials recycling.
2. The answer can be yes or no, depending on the circumstances. If the
products or packaging materials actually undergo biodegradation or
recycling, they will help reduce waste output; otherwise they don't.
Thus, when "biodegradable" diapers and "recyclable" packaging materials
are dumped into landfills, they are no different from other products or
materials. On the other hand, if biodegradable detergents are used in
the laundry, or if their recyclable boxes are recycled, then there'll be
some environmental benefits.
3. Because volume is what matters in a landfill, one might think the volumebased system is better, but the downside of the "pay by the bag" system
is that it encourages people to compact waste rather than reduce waste.
Therefore the weight-based system is probably the better of the two.
4. Six key criteria could include:
- Hydrogeology: Low probability of groundwater and surface water
contamination
- Landfill capacity: Preferably an anticipated lifetime of 20 years or more
- Accessibility: Good transportation routes, and preferably no more than 20
km of travel by dump trucks
- Present/future land use: Prime farmland, wetlands, future parks, etc. to
be avoided
- Impact on neighborhood: Preferably only a small number of people are
Page 138
negatively affected
- Downwind distance: Preferably 2000 m or more from nearest residential or
commercial neighbors
The hydrogeology requirement is probably more critical than any other.
5. Economically, recycling programs appear to cost municipalities (and hence
taxpayers) a great deal of money. However, one must remember that if the
recyclables are instead sent to the landfill, labor and tipping fees
would add up to about $78 a tonne (based on figures released in the same
study), which is higher than the average net cost for collecting, sorting
and selling a tonne of recycled materials. The bottom line: recycling
actually saves municipalities money. If one were to consider the
economic rewards of recycling to society at large (with the inclusion of
energy costs, pollution control costs, and so on) using full-cost
accounting, the payoff would be even greater.
Environmentally, the case for recycling (as opposed to no recycling) is
indisputable. Recycling reduces air pollution and greenhouse gas
production, water consumption and water pollution, deforestation, and
depletion of raw materials. One downside, however, is that too much
emphasis on recycling tends to undermine the need for source reduction,
the waste management practice of first choice.
18-E
1. No. of cars in 1997: 14.2 million (extrapolated from 1995 statistics)
No. of trucks, tractors, etc. in 1997: 10.0 million (guesstimate)
Adding the above two figures gives a total of 24.2 million cars and trucks
in Canada in 1997. Now if we assume that on average, each car or truck
has to replace 1.0 tire each year, then we have
24.2 million x 1.0 = 24.2 million (discarded tires in 1997)
2. (a)1 ha-m = 104 m2 x 1 m = 104 m3 of volume.
Of this volume, 25% is taken up by soil cover, 75% by waste.
Therefore,
Volume of waste = 0.75 x 104 m3 /14000 people/year
Weight of waste = (800 kg/m3 ) (0.75 x 104 m3 /14000 people/365
days)
= 1.2 kg/person/day
(b)Volume of landfill = (50 ha) (12 m) = 600 ha-m
Anticipated life = (600 ha-m) / (400,000 ha-m-yr-1 /14,000)
= 21 yrs
Page 139
Chapter 19
19-A
Hazardous and Toxic Wastes
TRUE-FALSE QUESTIONS
Where "F" is your answer, change the underlined portion (and the underlined
portion only) of the statement to make it true.
1. Toxic is a broader term and incorporates the more narrowly defined
hazardous group of substances.
2.Common examples of hazardous wastes include residues from oil refining and
biomedical wastes from hospitals.
3.It is estimated that annually, Canada produces some six million tonnes of
hazardous wastes.
4.Leading the world in hazardous waste generation, the United States has an
estimated annual total of 26 million tonnes.
5.Nearly all substances are toxic at some level of concentration or in
sufficiently high doses.
6.At the present time in North America, hazardous wastes are being generated
faster than they can be destroyed or detoxified.
7.Current incineration standards in North America require that all PCB wastes
entering an incinerator be converted to harmless substances with an
efficiency of 99.99%.
8.As of 1997, facilities do not exist in Canada for the proper incineration
and disposal of PCBs.
9.Of Canada's annual production of hazardous wastes, more than 50% originates
in Ontario.
10.The manufacture and most non-electrical uses of PCBs were prohibited in
Canada in 1977.
19-B
MATCHING QUESTIONS
Match each of Q.1-7 with the most appropriate item from the following list.
Any item in the list may be used more than once, or not at all.
a. "end-of-pipe" pollution control
b. Bhopal, India
c. Minamata, Japan
d. persistent toxic chemicals
e. nonpersistent toxic chemicals f.
heavy metals
g. the Canadian Arctic
h. chronic toxicity i. acute
toxicity
j. Love Canal
1.The inhabitants and the ecosystems there are especially vulnerable to toxic
contaminants in the environment.
2.Hundreds of people died, and thousands of people fell ill after eating
mercury-tainted seafood.
Page 140
3.Thousands of people were killed, and tens of thousands of people were
injured as a result of an accident at a Union Carbide pesticide plant.
4.The treatment and removal of pollutants after they have been produced.
5.Chemicals like dioxins and PCBs.
6.Chemicals like mercury and lead.
7.In our everyday life, we are mainly exposed to the risks of this type of
toxic effects.
19-C
MULTIPLE-CHOICE QUESTIONS
1.Toxic chemicals of the greatest concern are those that are
b. inorganic.
c. synthetic.
d. persistent.
a. organic.
2.The amount of a toxic substance that kills half the test population within
a certain time is termed
a. LD50.
b. a fatal dosage.
c. the 50/50
dosage.
d. sublethal dosage.
3.When an aquifer is contaminated with chemicals, it is
a. usually easy to
correct.
b. seldom physically or economically easy to correct.
c. normally a year or two before the effects of pollution will disappear.
d. nothing to worry about because natural processes will cleanse the
water within days.
4.Of the 70,000 or so chemicals in use in North America today, how many have
been classified by the EPA as definitely harmful or potentially harmful
to human health?
a. 5,000
b. 10,000
c. 35,000
d. 60,000
5.Controlling chemicals and their waste products is a major issue in most
a. developing countries.
b. developed countries.
c. agricultural
countries.
d. small-sized countries.
6.Which of the following is NOT an example of waste separation technology?
a. Stream stripping.
b. Air stripping.
c. Fixation.
d. Carbon
adsorption.
7.The best long-term solution to the hazardous waste problem is
a. secured landfill.
b. thermal treatment.
c. source reduction.
d. immobilization.
8.A properly designed and constructed sanitary landfill will
a. contain the
waste indefinitely.
b. still leak eventually.
c. leak in about 50
years' time.
d. leak after about 100 years.
9.Of the following uses of chlorine, which is the largest in terms of
quantity?
a. Plastics.
b. Pulp and paper bleaching.
c. Water
purification.
d. Solvents.
Page 141
10.Common sources of lead in the North American home today include all of the
following EXCEPT
a. drinking water from pipes.
b. air-borne lead from
gasoline.
c. old paint.
d. lead solder from seamed food cans.
11.Which of the following statements about PCBs is false?
a. There are more
than 200 forms of PCBs.
b. Some forms of PCBs are much more toxic than
others.
c. PCBs can now be completely destroyed by high-tech
incineration. d. PCBs are extremely persistent.
19-D
QUESTIONS FOR REVIEW, RESEARCH AND CRITICAL THINKING
1. (a)Define hazardous waste. How is hazardous waste classified on the basis
of its biological, chemical and physical characteristics? Give an
example of each category of hazardous waste.
(b)Differentiate between hazardous waste and toxic waste.
(c)Which category of hazardous waste is currently the focus of growing
public concern, and for what reasons?
2. (a)According to government figures, in the late 1980s about how much
hazardous waste, in tonnes, was generated in Ontario annually? And
in Canada annually? Do you have reason to suspect that the actual
amounts might have been much higher than the official figures?
Explain.
(b)What are the major sources of hazardous waste in Canada? In very
general terms, how is hazardous waste being managed by industry in
Canada? How well is hazardous waste being managed by industry
across Canada? (For background information, you may wish to consult
The State of Canada's Environment - 1991, Government of Canada,
1991)
3. What is the estimated total, in tonnes, of hazardous waste generated
annually by Canadians in their role as consumers? How does this amount
compare with the annual amount of hazardous waste produced by industry?
How significant, or insignificant, is the contribution from the general
public to the hazardous waste stream? Comment.
4. (a)In what ways can you as a consumer help in controlling and mitigating
the hazardous waste problem as you choose, buy, use and dispose of
consumer products?
(b)Which of the following are hazardous, and for what reasons?
AA/AAA batteries, baking soda, bug killer, hair shampoo, laundry
detergent, motor oil, paint thinner, rug cleaner, spray oven
cleaner, toilet bowl cleaner, vinegar, weed killer.
5. (a)What are heavy metals? What common biochemical properties of these
metals have made them a family of dangerous or potentially dangerous
environmental pollutants?
(b)Listed in the following table are two heavy metals of longstanding
environmental concern to North Americans. Complete the table.
Heavy metal
Major sources
Adverse effects on
Page 142
Control strategies
human health/wildlife
Lead
Mercury
6. What options are available to deal with the hazardous wastes (a) that are
already in hazardous waste dumps all across North America, and (b) that
are still being generated today and tomorrow? Are there better ways to
address the hazardous waste problem than merely monitoring and
controlling the output? If so, what are they?
7. Explain in your own words the meaning of LD50 . Why do you think such a
"peculiar" measure of toxicity has been adopted? Why not simply use
LD100? Is time a factor in the measurement of toxic effects?
8. In recent years the International Joint Commission (IJC) has repeatedly
called on the Canadian and US governments to sunset and eventually ban
the production and use of chlorine and organochlorines. At the same
time, the IJC has recommended that reverse onus of proof be applied to
the chemical industry as a prerequisite for introducing new chemicals.
(a)What findings have prompted the IJC call? What will be the
ramifications of such a ban to society at large?
(b)Name three organochlorine pollutants that are widely dispersed in the
Great Lakes basin and Great Lakes waters. What are their sources?
Have their concentration levels in Great Lakes waters been declining
in recent years, and if so, does it imply that if there has been a
problem, at least the problem is under control?
(c)What has been the response of the Canadian and US governments to the
IJC call? And of the chemical industry to the IJC recommendation?
(Note: For this question you may wish to consult IJC's Seventh Biennial
Report on Great Lakes Water Quality, released in February of 1994.)
9. In late 1994, an Ontario board's ruling in effect ended a 14-year quest by
the Ontario Waste Management Corporation (OWMC) to build a governmentfunded, state-of-the-art toxic waste disposal plant in the Niagara
region. Using literature available in the library, review the OWMC saga
from November 1980 to November 1994. Overall, do you agree with the
board about its decision to kill the project? What was the reason given
for rejecting the OWMC proposal, and was the reason a compelling one?
Was the environmental assessment process in this case too protracted and
too costly? Were its terms of reference overly stringent? What are the
ramifications of the board's decision for Ontarians today and tomorrow?
19-E
WORKING WITH NUMBERS AND GRAPHS
1.
If the acute (oral) LD50 of a certain chemical is 50 mg/kg for rats, what
probable single (oral) dose of the same chemical may be lethal to humans?
2.
The radius of a circular oil spill is increasing at the rate of 10 m/min.
How fast is the area of the spill increasing when the radius is 150 m?
Page 143
Chapter 19
Answers and Solutions
19-A
T: Q.2, 3, 5, 6, 9, 10
F: Q.1, 4, 7, 8
Q.1
Hazardous; toxic
Q.4
260 million tonnes
Q.7
99.9999%
Q.8
do exist in Canada (Alberta and Quebec)
19-B
1g
2c
3b
4a
5d
6f
7h
19-C
1d
2a
3b
4c
5b
6c
7c
8b
9a
10b
11c
19-D
1. (a)Hazardous waste is waste (solid, liquid or gaseous) that poses a risk
to humans or the environment, and requires special disposal
techniques. It is sometimes classified into these six groups:
- Toxic, e.g. pesticides.
- Reactive, e.g. pool chemicals.
- Flammable, e.g. used solvents.
- Corrosive, e.g. battery acid.
- Pathological, e.g. hospital wastes.
- Radioactive, e.g. used reactor fuels.
(b)Toxic waste is just one type of hazardous waste.
(c)Toxic waste, because it is widely dispersed in the environment and even
in trace amounts, could be harmful to humans and other forms of
life.
2. (a)About 4.5 million tonnes produced in Ontario, 6.5 million tonnes in
Canada. But the actual amount could have been much higher because
of noncompliance with reporting procedures.
(b)The major sources of hazardous waste in Canada are the chemical
industry, the automobile industry, mining operations and the paper
and pulp industry. Canadian industry manages its hazardous waste
using such "standard" practices as on-site treatment, storage,
shipping the waste elsewhere for treatment, and maybe even
intentional dumping. No one really knows how well all the hazardous
waste is being managed.
3. About 2.5 kg of hazardous waste per person per year, by some estimates.
This amounts to perhaps less than 1% of industry's contribution, but in
the context of environmental impacts, it's not so much the quantity of
the waste as how that quantity of waste is disposed of that really
matters. Individuals count.
4. (a)There are perhaps two general approaches a consumer can follow. The
first is to emphasize prevention and reduction - if a product is
highly hazardous, don't use it and work toward having it banned; or
if you do have to use it, use as little of it as you can. The
second is to emphasize management - use it and dispose of it
Page 144
properly.
(b)Hazardous:AA/AAA batteries (corrosive, toxic); bug killer (toxic);
motor oil (flammable); paint thinner (flammable); rug
cleaner (toxic); spray oven cleaner (toxic); toilet bowl
cleaner (corrosive); weed killer (toxic)
5.
(a)The term heavy metals is not precisely defined. Some scientists use it
to refer to metals with specific gravities greater than 5, but
loosely the term is just an expression for toxic metals. Heavy
metals (in trace amounts for some, in higher concentrations for
others) can cause damage to the nervous, circulatory, urinary, and
reproductive systems. Recent studies indicate that some of them can
disrupt the endocrine system also.
(b)
Heavy metal
Major sources
Adverse effects on
human health/wildlife
Control strategies
Lead
Mining/smelting,
paints, ceramic
glazes, lead
plumbing, solder
Brain/kidney damage,
hormone disruption and
birth defects.
Emission/effluent
control, phaseout
of lead in paint
and other products
Mercury
Electrical/paint/
chemical
industry, dental
fillings
Brain/kidney damage,
loss of vision,
hearing and muscle
coordination
Emission/effluent
control, use of
substitutes for
mercury
6. (a)The Superfund approach - Identify hazardous waste dumps, set
priorities, and clean up.
(b)Practice the 3Rs first, but also use regulations and technology to
manage all phases of the waste stream.
The best strategy, perhaps, is to adopt the "Prevention is better than
cure" approach. Eliminate the most hazardous substances at source, i.e.
ban their production and use.
7. LD50 is the dose of a substance that, if administered to a test population,
will kill half of its members (within a period of time). The adoption of
this measure of toxicity is a recognition of the fact that individual
members of a population respond differently to toxic substances, and
what's lethal dosage for one member may not be lethal for another. A
statistical measure therefore would be more meaningful. Though not
explicitly expressed in the definition of the term, time should be an
important factor: a single dose that kills instantly obviously will be
much larger than a regular daily dose that will cause death within, say,
two years. LD50 data obtained with lab animals generally refer to acute
dosages (dosages administered within 24 hours, resulting in death within
days or weeks), and are given in terms of the dose per kilogram of body
weight (of the test animal).
8. (a)There is considerable evidence (obtained in the Great Lakes region and
in other parts of the world) indicating that organochlorines are
very dangerous (endocrine-disrupting, carcinogenic, teratogenic...)
Page 145
chemicals and we can't afford to take chances with them. No other
course is open to us than phasing them out and eventually banning
them. The ramifications of the IJC recommendation are certainly
far-reaching for society. The economic impact alone - the jobs, the
sales, and the time and effort required for developing substitutes
for the organochlorines -would be enormous. On the other hand, if
no action is taken now and the warnings of the IJC scientists should
prove to be true, irreparable harm to the human species will have
been suffered.
(b)DDT (agricultural runoff); Dioxins and furans (agricultural runoff,
pulp and paper effluent discharge, incineration of chlorinecontaining substances); PCBs (Leakage from storage sites,
intentional dumping). A qualified yes: in the sense that levels of
most organochlorines in Great Lakes waters had been declining until
a few years ago, when they started to level off. But even if the
downward trend continues, it doesn't necessarily mean that the
organochlorine problem is under control. For one thing, adverse
long-term effects could be caused by persistent organochlorines in
even extremely small concentrations, owing to bioaccumulation,
biomagnification and other effects.
(c)The Canadian and US governments have sidestepped the IJC call. The
chemical industry has vigorously opposed the proposed ban as well as
the reverse onus of proof requirement for introducing new chemicals,
on grounds that the economic cost would be too high, and that if
there are problems with particular compounds, they should be looked
at individually.
9. For now, it probably makes economic sense for Ontario to mothball the OWMC
project. Already, a number of existing toxic waste treatment plants in
North America, including a Canadian one at Swan Hills, Alberta, are
operating well under their capacity. There just doesn't seem to be any
immediate need for an additional waste treatment facility in Ontario.
However, the reason for rejecting the OWMC proposal, as given by the
Ontario board, was that the board was not convinced the OWMC had found
the best way to manage the chloride salts (that would result from the
treatment of toxic wastes), which doesn't seem to constitute a compelling
reason for rejection. In the real world, there are no perfect solutions.
From the time the OWMC was created to the time an Ontario board turned down
its proposal (1980-94), a total of (Cdn) $140 million - $80 million on
environmental hearings alone - had been spent. Most people would
probably agree that in this case, the environmental assessment process
was too drawn-out and too costly indeed. In the end, Ontarians still
have to rely on out-of-the-province or out-of-the-country facilities to
treat their toxic wastes, and that could lead to problems in the future.
19-E
1. If the LD50 for rats is applicable to humans, and if an average human
weighs 70 kg, we have
LD50 for humans = (50 mg/kg) x 70 kg = 3500 mg
If we want to be extra cautious, we may apply a safety factor of 100 to the
above figure, resulting in
LD50 for humans (after adjustment) = 3500 mg / 100 = 35 mg
Page 146
2. The change in area is equal to:
3.1416 (1602 - 1502 ) m2 /min = 9700 m2 /min
Page 147
Chapter 20
20-A
Environmental Policy and Decision Making
TRUE-FALSE QUESTIONS
Where "F" is your answer, change the underlined portion (and the underlined
portion only) of the statement to make it true.
1.In the Canadian system, the legislative power and the judiciary power of
the government are joined, while the executive power remains separate.
2.Currently, with government emphasis on deficit reduction, environmental
issues are not high on Canada's political agenda.
3.The US Constitution has been amended to include environmental-quality
rights.
4.In late 1996, federal and provincial environment ministers met in Toronto
and signed a framework federal-provincial agreement to bring about
standardization of environmental protection laws in Canada by mid-1997.
5.According to the Provincial Auditor's 1996 report, air quality standards in
Ontario are some 20 years out of date.
6.In the past ten years, gains on the environmental front in Canada include
significant reductions in urban smog incidents and sulfur dioxide
emissions.
7.The United Nations has the power to pass and enforce international laws.
8.UNEP stands for the United Nations Environmental Program.
9.In 1995, over 100 countries worldwide have introduced eco-labels to
facilitate consumer choice of green products.
10.In Canada only the federal government has the power to pass laws relating
to the environment.
20-B
MATCHING QUESTIONS
Match each of Q.1-7 with the most appropriate item from the following list.
Any item in the list may be used more than once, or not at all.
a. Wise-use movement
b. eco-terrorism
c. IDA
d. end-of-pipe control
e. command-and-control approach
f. Infoterra
g. Environmental
Protection Agency (EPA)
h. the developing South
1.It provides access to a vast pool of global environmental data.
2.It advocates, among other things, opening all public lands to mineral,
energy and timber production.
3.Its regulations have the force of law in the US.
4.It is a lending agency that finances development projects in the poorer
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member countries of the UN.
5.Its share of the world total of greenhouse gas production is likely to
substantially increase in the next few decades.
6.It is pollution control and abatement rather than pollution prevention.
7.It relies on regulation rather than market forces.
20-C
MULTIPLE-CHOICE QUESTIONS
1.The
branch of the Government of Canada is empowered to propose
legislation, present budgets and implement laws.
a. executive
b. legislative
c. judiciary
d. administrative
2.Out of the 1972 UN Conference on the Human Environment in Stockholm was
born the
a. Draft Convention on the Law of the Sea.
b. International
Union for the Conservation of Nature.
c. Global Environmental Facility.
d. United Nations Environment Program.
3.The establishment of the Environmental Protection Agency in the US in 1970
was in response to
a. a public outcry against DDT contamination of the
environment.
b. a series of highly publicized environmental problems
and incidents, such as the near extinction of the bald eagle and the
Santa Barbara oil spill.
c. public concern over acid deposition.
d. a
petition for new environmental laws and standards submitted to Congress
by Greenpeace.
4.Protection of the fishery resources off Canada's East Coast comes under the
jurisdiction of the
a. federal government.
b. Nova Scotia government.
c. Newfoundland government.
d. governments of all the Maritime
Provinces.
5.When seeking environmental approval for an activity/project, Canadian
industry would apply to an agency/department at the
.
a. federal
level
b. provincial level
c. municipal level
d. a or b or c, or
some combination of them
6.Which of the following resources/activities in Canada are/is NOT regulated
exclusively by the federal government?
a. Salmon and cod fisheries.
b. The manufacturing and distribution of pesticides.
c.
Environmental impact assessments of projects.
d. Shipping.
7.Conservation issues that put Canada on the hot seat in 1996 include all of
the following EXCEPT
a. the logging of old pines in Temagami (Ontario).
b. the commercial development in Banff National Park.
c. the lack
of progress in the protection of endangered species.
d. setting
land aside for national parks in the Northwest Territories.
8.According to Ontario's Ministry of Environment estimates (Ontario
population in 1996: about 11 million), some
Ontarians died
prematurely each year during the mid-1990s because of poor air quality.
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a. 75
b. 1,800
c. 8,000
d. 22,000
9.Under a voluntary auto emissions testing program recently introduced in
Toronto, owners of pre-1987 cars found to be gross polluters would be
offered
to retire their cars.
a. $100
b. $1,000
c. $400
d. $800
10.Statistics Canada is set to begin a new system of national wealth
accounting in June, 1997 that will include Canada's
a. increasing or
declining stocks of natural resources.
b. waste production and costs of
its disposal and management.
c. costs of environmental protection
programs.
d. all of the above.
20-D
QUESTIONS FOR REVIEW, RESEARCH AND CRITICAL THINKING
1. Would protecting the environment lead to increased rates of industry and
business failures, and job losses? Would environmental protection drain
our resources and lower our standard of living? Can we really afford to
protect the environment?
2. "Our politicians lack the political will to take actions on environmental
issues, hence the sorry state of our environment." Do you agree or
disagree with the statement? Elaborate.
3. Suggest an effective strategy to get industries/businesses to give up their
environmentally unfriendly practices.
4. "Within Canada's system of national accounting, we have a wealth account,
but we couldn't take account of our loss in natural capital." Explain
and elaborate. Give your interpretation of the term natural capital.
5. Proposals like hiking taxes on gasoline, increasing water rates, and
requiring old, polluting cars to be fixed or retired (all for the purpose
of curbing consumption and/or reducing pollution) have all been opposed
on grounds that such measures will hurt the poor disproportionately.
What is your view? Can we protect the environment and the poor at the
same time?
6. Critics of Canadian and US environmental policies charge that in recent
years, huge amounts of money have been wasted on relatively minor
environmental hazards or perceived risks (e.g. the removal of asbestos
from schools and the cleanup of toxic waste dumps), when the money could
have been better spent on redressing social ills. What is your point of
view? What yardsticks would you use to determine whether or not a
certain environmental protection program is worth the money?
20-E
WORKING WITH NUMBERS AND GRAPHS
1. According to a cost-benefit model, the relationship between the cost of
pollution control and the amount of harmful pollutants removed is given
by y = (6.7x)/(100 - x), where y is the pollution control costs in
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millions of dollars, and x is the amount, in %, of pollutants removed.
a) Graph the function. Comment on its characteristics.
b) Find the cost for removing 50% of the pollutant. Ditto for 70%, 90%
and 99.9%. What obvious conclusion can you draw from comparing
these costs?
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Chapter 20
Answers and Solutions
20-A
T: Q.2, 4, 5, 8
F: Q.1, 3, 6, 7, 9, 10
Q.1 the legislative power and the executive power; the judiciary power
Q.3 has not been amended to include environmental-quality rights
Q.6 municipal solid waste recycling programs and reductions in sulfur
dioxide emissions
Q.7 does not have the power to pass and enforce international laws
Q.9 over a dozen countries
Q.10both the federal government and the provincial governments have the
power
20-B
1f
2a
3g
4c
5h
6d
7e
20-C
1a
2d
3b
4a
5d
6c
7d
8b
9c
10d
20-D
1. It depends on how far we're prepared to go with environmental protection.
If carried to the extremes, environmental protection of course could
cause widespread industry/business failures and job losses, but that
scenario is highly improbable considering the fact that most of us are
just moderate greens. When environmental protection is practiced with
moderation, what is likely to happen is that some industries/businesses
will fail and some jobs will be lost, but at the same time, other
industries and other jobs will emerge. On balance, the impact on
employment opportunities should be positive, for the simple reason that
environmental improvement is a major undertaking. As for the resource
deployment and costs, people in the developed countries should be well
able to afford them, though the price tag may not be insignificant (say
10% of GNP). People in the poorest developing countries, however, may
find the costs of environmental protection unbearable. On a global
scale, therefore, combating poverty goes hand in hand with combating
environmental degradation.
2. True, but that's only half the story. The reason why politicians don't
take actions is because we haven't expressed our environmental likes and
dislikes to them loudly and clearly enough . Politicians mostly respond
and react, so if we want change, we have to let them know.
3. One strategy would be to hit them where it hurts most - at the level of
selling their products. Rather than seeking direct government
intervention and regulation, it may be more effective to mobilize the
public to boycott their products, or lobby and form alliance with other
businesses that are their big customers. Greenpeace, for example,
successfully persuaded some American and European corporations to buy
paper and timber from only those Canadian forest products companies with
good forestry management records.
4. A nation's natural capital may be interpreted as the aggregate worth (in
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both economic and noneconomic terms) inherent in its mineral and energy
resources, fish stocks and forests, clean air and water, pristine
wilderness, and so on. In the existing system of national accounting,
however, the values of none of the above natural assets - nor their
depletion/depreciation/degradation - are reflected in the GDP or other
economic indicators, hence the statement.
5. Answers will vary. Here's one view.
Environmental laws and standards perhaps should be evaluated from the
perspective of their benefits and costs to society at large, rather than
their impact on specific groups of people. (If we focus our attention
only on specific groups, then arguably almost all environmental laws and
regulations should be opposed because setting effluent and emissions
standards hurts certain industries and their workers, enforcing a
forestry practices code hurts forestry companies and loggers, limiting
allowable catches hurts some fishermen, and on and on it goes.) If
careful analysis shows that the overall benefits of an environmental
protection program outweigh the costs or drawbacks, we should support it.
It is then up to us to press for tax credits and subsidies for the poor
so as to lessen the blow to them.
6. In some cases, it may well be that we're not getting our money's worth, but
by and large, there's no easy answer to this question. Money spent on
environmental protection today could be viewed as partly for quick fixes,
partly for longer-term investment and partly for insurance. Even in the
quick fixes area (e.g. the cleanup of an oil spill in coastal waters),
there's debate as to whether the cleanup costs can be justified, let
alone the grayer areas of longer-term investment and insurance. To a
large extent, the answer depends on the available facts and evidence,
one's view of nature and fellow human beings, one's understanding and
perception of environmental problems and risks, one's social, economic
and ethical values, and so on.
To decide whether an environmental program is worth the money, people may
want to ask (other than "How is it going to affect me?") these questions:
How many people altogether are likely to be affected by the
environmental problem at hand? In what ways? How likely is the
perceived environmental damage going to occur? Is the damage long-term
and irreversible? How are ecosystems and wildlife affected? Are the
environmental protection costs justified by immediate or longer-term
benefits? For the same money, would other social/national programs give
us higher dividends?
20-E
a) The graph of y (the pollution control costs, on the y-axis) versus x (the
% of pollutants removed, on the x-axis) gives a curve that exhibits
the characteristics of exponential growth. The costs of removing each
additional 10%, say, of pollutants quickly escalates after the 70%
level.
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b)
Pollutants
removed
50%
70%
Pollution
control
costs
$6.7
$15.6
million
million
90%
$60.3
million
99.9%
$6690
million
The figures show that (once the pollutants are produced) the cost of
removing each additional unit of pollutant increases sharply. Beyond a
certain point, pollution control becomes increasingly uneconomic and
eventually unaffordable.
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