HONORS LIVING ENVIRONMENT
MS. ETRI
TOPIC 23: ECOLOGY
PART 5: HUMAN IMPACT ON THE ENVIRONMENT
RENEWABLE RESOURCES
 Resources that can be replaced.
 Are infinite, but still must be used carefully.
o Increased consumption can stress the natural process that renew some resources.
 EXAMPLES: wind and solar energy
NONRENEWABLE RESOURCES
 Once they are used (increased consumption), they cannot be replaced naturally.
 Are finite.
 EXAMPLES:
o most metals (such as the aluminum we use for packaging),
o fossil fuels (such as the gas that runs our cars and the coal that powers many factories)
 OIL
 COAL
 NATURAL GAS
o minerals (such as the silicon we use for computer chips).
 Using too many nonrenewable resources will cause their depletion (serious reduction) within a
relatively short time.
Preserving Our Resources: Individuals can help maintain our supply of both renewable and nonrenewable
resources by practicing the three R’s—Reduce, Reuse and Recycle.
*One way to reduce our use of resources is to control the growth rate of our population. An ever-increasing
human population accelerates the use of Earth’s limited resources.
HUMAN ACTIVITIES AND THE LOSS OF DIVERSITY
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HONORS LIVING ENVIRONMENT
MS. ETRI
 Some human activities that destroy habitats and degrade ecosystems do far more than damage
individual organisms. They also destroy diversity in both the living and nonliving parts of the
environment.
o EXAMPLE: when humans use land to build a parking lot, the organisms that lived on that land
are likely to die. Other organisms that ate the plants, burrowed through the ground, or nested in
the nearby trees are also affected.
 There will be fewer resources available for a variety of species.
1. GLOBAL WARMING
o Sunlight passes through the gases in the atmosphere to reach Earth. But some of these
atmospheric gases, called greenhouse gases, also trap and absorb the infrared radiation
that bounces off Earth’s warmed surface.
 For thousands of years, this has kept Earth warm.
 In recent years, the amount of greenhouse gases has increased.
o
o
o
o
WHAT HAPPENS?
 Earth’s atmosphere traps some of the heat that would normally radiate into space.
 The result is that Earth’s average temperature is rising!
WHAT IS THE RESULT?
 The increase in temperature (global warming), could lead to changes in climate
patterns and even to the melting of ice caps at the North and South Poles.
 When ice caps melt, a rise in sea level will occur, flooding many coastal habitats.
WHAT IS IT CAUSED BY?
 Burning of fuel for transportation and industry.
 Carbon dioxide is released when fossil fuels are burned.
WHAT CAN BE DONE?
 Finding and using energy sources that do not add carbon dioxide to the atmosphere.
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HONORS LIVING ENVIRONMENT
MS. ETRI
 Grow long-living trees! Because trees remove large quantities of carbon dioxide during
photosynthesis and store it in their tissues as carbon compounds, growing more longlived trees could help solve the problem.
2. ACID RAIN
o Fossil fuels CREATE Acid rain.
o Sulfur and nitrogen compounds that
are produced when fossil fuels burn
can combine with moisture in the
atmosphere.
o When this moisture falls to Earth as
acid rain, snow or other precipitation, it
has a low pH level and is much more
acidic than normal precipitation.
 WHAT CAN HAPPEN?
o Enzymes denature in organisms—
they die.
o Lower pH levels in lakes can be
deadly to algae, fish eggs, and other
organisms.
o Producer organisms (algae) are
killed.
 Food chains are disrupted.
 Loss of biodiversity.
o Damaged plants are more
susceptible to attacks by fungi or
insects.
WHAT CAN BE DONE?
o Burn fewer fossil fuels.
o Use alternative energy forms;
conserve energy; Reduce, reuse,
recycle.
3. OZONE DEPLETION (HOLE IN THE OZONE LAYER)
WHAT IS IT?
o The release of certain industrial gases into the atmosphere has led to destruction of much of the ozone
shield—the layer of ozone gas in the UPPER atmosphere that protects Earth from some of the
sun’s radiation.
WHAT ARE THE CAUSES?
o GASES—chlorofluorocarbons, CFCs.
o Used as coolants in refrigerators and air conditioners, as propellants in aerosol cans, and in the
manufacture of plastic foam.
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HONORS LIVING ENVIRONMENT
WHAT ARE THE EFFECTS?
o The thinning “hole” in the ozone shield
allows above normal amounts of
ultraviolet radiation from the sun to
reach Earth’s surface.
o Ultraviolet radiation can cause genetic
mutations and can kill cells that are
exposed to it.
o An increase in UV radiation could result in
more cases of skin cancer.
o Destroy producer organisms in the
oceans.
o Disrupt food chains.
o Reduce the amount of oxygen
released by producers.
WHAT CAN BE DONE?
o Some steps have been taken to reduce the
release of CFCs.
o Researchers have found alternative to the
products that cause the most damage.
o International agreements have been made to
reduce emissions of the harmful gases.
MS. ETRI
REMEMBER:
o OZONE DEPLETION is caused by the
RELEASE OF CFCs into the atmosphere
o This results in harmful UV rays which
cause SUN BURNS, SKIN CANCER.
o GLOBAL WARMING is caused by BURNING
FOSSIL FUELS which increases the warming
of the Earth.
4.
o
o
o
INDUSTRALIZATION
The use of machinery to produce large numbers of products.
These products may add to the quality of life, but their manufacture can harm the environment.
In addition to contributing to pollution of the air and water, industrialization increases the demand
for energy, water, fossil and nuclear fuels.
WHAT ARE THE EFFECTS?
o Additional power plants (to meet higher energy demands) add to the pollution of air and water.
o Nuclear fuel is an energy source that results from splitting atoms.
o Nuclear power plants do not pollute the air or water with toxic chemicals, but they can cause
thermal pollution of waterways.
o Disposal of radioactive nuclear wastes is an environmental problem.
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HONORS LIVING ENVIRONMENT
MS. ETRI
o Most factories use a lot of water.
o Large wells drilled or factories dry up nearby
smaller wells that individuals use to supply their
homes.
o Sometimes, withdrawing large quantities of water
causes the ground to collapse, forming sinkholes.
o In dry climates, reducing the supply of groundwater
can have serious consequences for native plants
and the consumers that depend on them for food.
WHAT CAN BE DONE?
o REDUCE our demand foe energy and manufactured
goods.
o REUSE manufactured products rather than discard them.
o RECYCLE as many products as possible, conserving both energy and resources in the process.
5. DEFORESTATION/LOSS OF ANIMAL HABITAT
o Habitat destruction occurs when people take over land for their own use.
o It is an important way that species become endangered—they have no where to live! 
o As habitats are destroyed, whole ecosystems can be damaged and entire species may become
extinct.
WHAT IS IT?
o DEFORESTATION—the destruction of
forests resulting from human activity.
o People clear forests by burning or
cutting down trees.
o Due to deforestation, the area
covered by the world’s rain forests is
only about half as large as the area
covered 150 years ago.
WHAT ARE THE EFFECTS?
o Loss of habitat
o Disruption of food chains
o Loss of biodiversity.
o Trees and plants remove carbon dioxide
from the atmosphere. With fewer trees,
there can be an increase in global
temperature.
WHAT CAN BE DONE?
o Limit deforestation
o Recycle paper
o Set up land preservations
o Replant trees.
6. LOSS OF BIODIVERSITY
o BIODIVERSITY: When a wide variety of different species live together in an ecosystem
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HONORS LIVING ENVIRONMENT
MS. ETRI
o A REDUCTION in biodiversity occurs when species are lost.
WHAT ARE THE CAUSES?
o HABITAT DESTRUCTION (DEFORESTATION) can lead to loss of biodiversity.
o A farmer might plow under a meadow that is home to many species. Then the farmer might plant a
single crop (corn or wheat) on many continuous acres of land.
o This also reduces the biodiversity of the area.
o Creates an ideal environment for insects to feed on crops.
WHAT ARE THE EFFECTS?
o Can affect the health of whole ecosystems and food webs.
o Can even affect the proportion of gases in the atmosphere.
o Our future ability to find new medicines for treating diseases or to discover new sources of genes that
could be genetically engineered into more productive and pest-resistant crops is threatened when
biodiversity is lost.
WHAT CAN BE DONE?
o Create protected areas where human activity is limited.
o Prevent species introductions
o Sustainable agriculture (rather than cropping that relies on clearing strips of forest or field).
7. INTRODUCTION OF A FOREIGN SPECIES TO A GIVEN AREA
o Biodiversity is often reduced when people import and release a species from one environment
into another.
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HONORS LIVING ENVIRONMENT
MS. ETRI
o The release may be inadvertent or intentional.
o EXAMPLE: Prior to 1859, there we no rabbits in Australia!
o By 1953, more than a billion rabbits occupied 1.2 million square miles of the continent.
o These rabbits ate massive amounts of vegetation (plant material) ordinarily available
to the native species.
WHAT ARE THE EFFECTS? MANY SPECIES BECOME PESTS!
o Because the new organisms are not part of an existing food web in the area, they often have
no natural enemies in their new environment and rapidly overpopulate the area.
o They then crowd out, feed on, or otherwise eliminate native species.
o Disrupt food chains
o Reduce biodiversity
o Lead to extinctions of native organisms.
o EXAMPLES: Japanese beetles and gypsy moths (accidently released in the U.S.)
WHAT CAN BE DONE?
ONCE AN IMPORTED SPECIES BECOMES A PEST, IT IS DIFFICULT TO SOLVE!
o BRING IN ANOTHER SPECIES: if another species is imported to control it, the second
species may choose to feed on native organisms, adding another problem.
o USING PESTICIDES OR POISONS: These can kill other organisms in addition to the
imported species.
o DISEASE: sometimes scientists find a disease organism that only affects the imported
species. However, there is always a risk that the species may become resistant to the
disease and overpopulate again.
o LAWS: Many states and countries have laws to restrict the transport of fruits and
vegetables.
o The goal is to avoid introducing diseases or insects that might damage local crops.
o TRAPS: One safe pest control method is setting traps that use chemical scents that
attract insects.
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HONORS LIVING ENVIRONMENT
MS. ETRI
o No other species are harmed and the population of the pest species can be reduced
to a safe level.
o BREEDING AND RELEASING NATIVE PREDATORS (of a pest species) has been used
successfully and without harm to other species.
VERSUS DIRECT HARVESTING: The destruction or removal of species from their habitat that can
sometimes lead to the extinction of a species. (Example: Overfishing, killing elephants for their husks, monkeys
in homes, and whales for blubber.)
8. WATER POLLUTION (INCLUDE THERMAL POLLUTION)
o The addition of pollutants to natural environments causes water pollution, which can change the
abiotic conditions in ecosystems.
o EXAMPLE: Sewage and animal wastes act as fertilizer, increasing the growth of
plants, algae and the bacteria in aquatic systems.
 Plants consume oxygen all the time, day and night. Photosynthesis stops at night
because it requires light. Therefore, oxygen production stops.
 Oxygen levels drop, and many organisms suffocate.
 When these organisms die, oxygen-using decomposers begin their decay
activity, which further decreases the oxygen supply.
o WHAT IS IT CAUSED BY?
o SEWAGE CONTAMINATION
o RUN OFF (from highways containing oil)
o PATHOGENS
o OIL SPILLS
o PCBs (POLYCHLORINATED BIPHENYLS—man made chemicals. Used in synthetic
materials, insulation, paints, inks, brake fluid, etc.)
o
TOXIC
WASTES:
o
o
o
Chemical fertilizers and weed and insect killers can be washed off farmlands into
streams or rivers.
The chemicals collect in the cells or organisms living in the water and along the
shore.
These toxic materials move through the food chain and eventually damage or kill
many kinds of organisms.
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HONORS LIVING ENVIRONMENT
MS. ETRI
 BIOMAGNIFICATION/BIOACCUMULATION: As you move up through the
food chain, the concentration of the toxins increase.
 TOP of the food chain is impacted the most. They are most likely to
accumulate enough of the chemical to cause them harm.
 EXAMPLE: Pesticide DDT—fish-eating birds at the top of the food
chain produced eggs with very thin shells which broke easily, killing
the next generation of birds before they even hatched.
 HOW?
o Small quantities of toxic substances are absorbed into the
cells of algae and other producers living in the water.
o When those producers are eaten by small herbivores , the
toxins are stored in the herbivore’s fatty tissue.
o There it stays until the herbivore is eaten by the next
consumer in the food chain.
o **At each level of the chain, larger and larger amounts of
toxic material collect in the fatty tissue.”
o
THERMAL POLLUTION
o Some power plants and industries use water to cool their machines or materials.
o The warmed water is then released into a river or lake and the water temperature rises.
o Because warm water cannot hold as much dissolved oxygen as cold water, the oxygen levels
decreases as water temperature rises.
o Some species may suffocate as a result of thermal pollution; others may be forced to find a new
home 
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HONORS LIVING ENVIRONMENT
MS. ETRI
o WHAT CAN BE DONE?
o Conserve energy by using less power.
o Sewage can be treated before it is discharged into waterways.
o Toxic wastes can be separated from other materials and recycled or stored safely.
o Methods could be developed for cooling industrial processes that would reduce their damage to
the environment.
9. AIR POLLUTION / LAND POLLUTION
o Most pollutants released into the atmosphere wind up in the water cycle and return to the water or land.
o Air pollution can damage habitats and harm the organisms that live in them.
o WHAT IS IT CAUSED BY?
 BURNING FOSSIL FUELS
 FOSSIL FUELS: coal and gas that formed from the remains of organisms that
lived millions of years ago.
 When burned, carbon dioxide and other gases containing sulfur and/or
nitrogen are added to the air.
o WHAT ARE THE EFFECTS?
o Landfills are becoming over filled.
o Soil loss due to toxic chemicals
entering the ground causing soil
to become unstable and
unusable.
o Build up of garbage and a
growing need of places for
garbage disposal.
o SMOG is a type of air pollution
that results when certain
pollutants react with sunlight.
 Individuals with
respiratory diseases are
especially sensitive to air
pollution and may be in
danger when air pollution
is intense.
REMEMBER…
o For each environmental problem, people must learn to assess the risk to the ecosystem.
o For each environmental solution, they must learn to analyze the costs and benefits.
o THEN they must determine which trade-off (COMPROMISE) is acceptable and which is simply
too dangerous to the welfare of future generations.
o Today’s decisions affect the next generation.
o Many important decisions about the environment are made by states and nations, but a
surprising number of important decisions are made each day by individuals.
o If our environmental problems are not recognized and solved, the long-term damage will be
irreversible and severe.
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HONORS LIVING ENVIRONMENT
MS. ETRI
o On the other hand, cooperation by individuals and nations can help maintain the stability of the
ecosystems upon which all life depends.
o Making people aware of the successful results of the collective actions of many separate individuals
may be the most promising approach to solving ecological problems.
o Our resources come from nature, be sure to take care of it! 
THANK YOU FOR A WONDERFUL YEAR!
GOOD LUCK ON THE REGENTS AND STUDY HARD!
I AM SO PROUD OF ALL OF YOU!
LOVE, MS. ETRI
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