Environmental Science
LIVE & LET LIVE
What is Environmental Science?
The study of how humans interact with
their environment
Our environment is everything that
surrounds us, both natural and manmade.
ENVIRONMENTAL KNOWLEDGE
• It is essential
 To identify the env. problems
 To know the root cause of the problems
 To know the intensity and effect of the env. problems
To attain a knowledge and understand the diff.
processes of ecological systems which in turn helps to
solve the problems.
To develop an appropriate technology which will
advocate safe, creative, environmentally sound and
suitable solutions to the env. problems.
Objectives of Environmental Education
• Knowledge
• Participation - working towards stainable development
• Values - to develop an ethic of respect and responsibility for
the environment.
• Skills - acquire skill to identify the env. Problems – work with
others to resolve, minimize and prevent them.
• Awareness - create awareness and promoting env. Friendly life
style
• R&D Activities
• Environmental related Laws.
• To adopt technology without affecting the environment.
• To maintain the Quality of the ENVIRONMENT.
Importance of Environmental Education
• To know the current environmental issues
- like waste management, global warming
• To develop scientific principles
- R&D activities to solve the problems.
• To maintain the ecological balance
- by providing the basic operating knowledge of env.sys.
• To gain skills
- analyzing various env. Issues.
• Knowledge / R&D Activities / Active participation
• Environmental related Laws.
• To enable co-operation at Regional / National / International
level on environmental issues.
• To achieve SD.
• Environmental Studies – Impact on the society and
involvement of the society in combating the causes of env.
Degradation.
• Environmental Science – Systematic study of biotic and
abiotic inter relationship.
• Env. Engg. - causes and effects of pollutants
• Env. Chemistry
- study of various chemical phenomena
taking place in diff. segment of env.
• Env. And Ecology – interdisciplinary in nature and biology,
chemistry, geography, agri, etc.,
FORMAL EDUCATION
• Awareness programme through children and youth - - they
create new idea
• Inter disciplinary approach adopted
– To achieve sustain
• Hands on experience
– Education must be imparted not only through books but
also through first hand experience in field activities.
NON FORMAL EDUCATION
• It organises extracurricular activities like
eco development camp,
posters,
competition,
exhibition,
seminar,
club activities, mobile exhibition
• Other activities like tree plantation, fencing,
cleaning water bodies
• Education through arts, crafts, street plays,
Advertisement, etc.,
Env. Edu. Organization
Government Organization
Ministry of Env.
in the Central
Govt.
Depts. of Env. in
Diff. States
Non-Government
Organization
SPCB
CPCB
Mass Media
Centre for Env.
Edu, Ahmadabad,
News paper
Magazine
Radio, TV,
Awareness through
seminar/conf/Posters/short film/Advt.
Env. Edu. Through children/coll.students
Env. Info. System (EIS)
World Env. Day 5th June
Training Programmes & R&D
Env. Society of
India,
Chandigargh
Madras Env.
Society
Living things
+
Nonliving things
= ECOSYSTEM
• Ecosystem – A group of organisms interacting among
themselves and with environment is known as ecosystem.
Types of Ecosystem
Artificial/Man-made
Natural
Terrestrial
(Forest, Grass
land, Desert) Marine
Aquatic
Fresh water
Lotic -river, stream or spring.
Lentic -lake, pond or swamp.
Name the three members in
every community.
Producers
Consumers
Decomposers
All energy in a
food web comes
from the…
What makes ecosystems different?
Amount of water
1
Amount of sunlight
2
3
Type of soil
Ecology:
Study of the distribution and abundance of organisms, the flows of energy
and materials between abiotic and biotic components of an ecosystem.
Two Types:
1. Autoecology: The study of the individual organism.
2. Synecology : The study of the group of organisms.
Ecosystem Structure:
The living components of an ecosystem /
The roles of organisms in an ecosystem:
• Producer (autotrophy): make food; plants, algae
• Consumer (heterotrophy): eat other organisms
• Decomposer: eat dead organic matter; bacteria and fungi
Classes of Consumers
Herbivore – primary consumer – eats plants
Carnivores – secondary – meat eaters; eat herbivores
Omnivores – eat plants/animals.
What causes ecosystems to change?
Natural causes:
1
Drought
Disease
3
2
Fire
4
Overpopulation
What causes ecosystems to change?
Changes caused by humans:
1
Water pollution
2
Air pollution
3
Land pollution
4
Construction
How can humans help to prevent
changes in ecosystems?
1
Use resources wisely
2
Laws that control pollution
3
Clean up litter
4
Keep rivers and lakes clean
Structure of an Ecosystems:
BIOTIC components
• The biotic components of an ecosystem can be
classified according to their mode of energy
acquisition.
• In this type of classification, there are:
•
Autotrophs and Heterotrophs
• Organisms that produce their own food from an
energy source, such as the sun, and inorganic
compounds.
• Organisms that consume other organisms as a food
source.
Structure of an Ecosystems:
ABIOTIC components
• Solar energy provides practically all the energy for
ecosystems.
• Inorganic substances, e.g., sulfur, boron, tend to
cycle through ecosystems.
• Organic compounds, such as proteins, carbohydrates,
lipids, and other complex molecules, form a link
between biotic and abiotic components of the
system.
Structure of an Ecosystems:
ABIOTIC components
• Physical Factors:
- Light, Temp, Gravity, Pressure, Humidity
• Chemical Factors:
- O2, CO2, Minerals, Org. Matters such as
carbohydrates, proteins, lipids
Trophic level: All the organisms that are
the same number of food-chain steps
from the primary source of energy
FUNCTIONS OF AN ECOSYSTEM
1. FOOD CHAIN and FOOD WEB.
2. ENERGY FLOW
3. NUTRIENT CYCLE
Food Chains
Transfer of energy and nutrients from one
feeding group of organism to another in a
series.
• The producers, consumers, and decomposers of
each ecosystem make up a food chain.
• There are many food chains in an ecosystem.
• Food chains show where energy is transferred and
not who eats who.
Example of a Food Chain
Types of Food Chains
• Grazing food chain
Plants
Herbivores
(cattle, elephant, etc.)
Prim.Carnivores
(tigers, lions, snakes, etc.)
Second.Carnivores (hawk, owl, fox, etc.)
Types of Food Chains
• Detritus Food Chain - The org. waste and dead matter
derived from grazing food chains are called detritus.
Dead Organic Materials (Decomposing org.matter)
Detrivores (Algae, Fungi, Bacteria, earthworms, etc.,)
Chemical Energy -- Simpler Org. Compds
CO2 + H2O
• Detritus food chain
Food Webs
 In ecosystems, some consumers feed on a single
species, but most consumers have multiple food
sources.
 Hawk eats both mouse and snake.
 In this way, individual food chain becomes interconnected to form a food web.
Food Webs
Maintaining the stability of an eco system
ENERGY FLOW IN ECOSYSTEM
ENERGY FLOW IN ECOSYSTEM
• All organisms must obtain a supply of energy and nutrients from
their environment in order to survive.
• The transformations of energy in an ecosystem begin first with the
input of energy from the sun.
• Because, it is the first step in the production of energy for living
things, it is called “Primary production”.
• Photosynthesis -- Chemical reaction where green plants use water &
carbon dioxide to store the sun’s energy in glucose.
• ENERGY is stored in glucose. Glucose is stored as starch in plants
• The energy contained within producers and consumers is ultimately
passed to the decomposers that are responsible for the constant
recycling of nutrients.
ENERGY FLOW IN ECOSYSTEM
• Thus, there is a one-way flow of energy through the biotic
community and a cycling of nutrients between the biotic and
abiotic components of the ecosystem
• Energy flow cannot occur in reverse direction.
• The amount of energy decreases with successive trophic
levels.
• Only About 1% of energy from the sun is used by green plants
& rest remains unutilized.
• Similarly, there is loss of energy in each trophic level.
• The transfer of food energy between the organisms in an
ecosystem can be tracked by constructing food chains, food
webs, pyramids of numbers, biomass, etc.,
NUTRIENT CYCLES
• Nutrient cycles involve storage and transfer of
nutrients through different components of the
ecosystem, so that the nutrients are
repeatedly used.
• The cyclic movements of chemical elements of
the biosphere between the organisms and
environment are referred as
“BIOGEOCHEMICAL CYCLES”
BIOGEOCHEMICAL CYCLES
• It involves biological, geological and chemical
systems and all are interlinked through a cyclic
chain.
• It is the complete pathway that a chemical element
flows from the atmosphere, water, rock or soil to the
living organisms and again back to the atmosphere,
water, rock or soil.
• The return of chemical elements from living
organisms to abiotic component is called
Mineralization.
CYCLE OF NUTRIENTS
PLANTS
NUTRIENTS
ANIMALS
MICROORGANISMS
• There are 6 different biochemical cycles
– Hydrological cycle (water)
– Carbon cycle
– Nitrogen cycle
– Oxygen cycle
– Phosphorous cycle
– Sulfur cycle
HYDROLOGIC CYCLE
• In this cycle, fresh water evaporates and
condenses on the earth. Oceans are the main
source of evaporated water, which leaves
behind salts.
• Water also evaporates from fresh water
bodies, from land and plants.
HYDROLOGIC CYCLE
The steps involved in hydrologic cycles are
–
–
–
–
–
Evaporation
Condensation
Precipitation
Infiltration
Runoff
CARBON CYCLE
• Carbon enters plants as CO2
– Bacteria process carbon in a fashion that allows it to be
recycled.
– Obtain energy from the molecules, and convert
carbohydrates to carbon dioxide as a result of respiration.
• In Short term cycling, C enter in to living organism through
photosynthesis, respiration and Decay.
• In Long term cycling, involves organic deposits, fossil fuels and
inorganic deposits like lime stones.
• CO2 from Air + H2O------ HCO3 (source of C for aquatic
producers)
RESPIRATION
AIR
PLANTS
CO2
DEATH
RESPIRATION
FOOD
WOOD
FOSSIL FUEL
ANIMAL
BURNING
COMBUSTION
Fig.2.11.2 Carbon Cycle
The source of atmospheric carbon dioxide is variable but only plants can utilize atmospheric
carbon directly
NITROGEN CYCLE
• Nitrogen is crucial for all organisms
– Nucleic acids
– Proteins
– Chlorophyll
• Nitrogen- 78% in Atmosphere
• N2 is very stable and must be broken apart by
organisms, combined with other atoms into a usable
form.
• The process of entering atm. Nitrogen into the
organism and again back to the environment
completes the Nitrogen cycle.
Nitrogen Cycle- N2 gas into NO3• Nitrogen in Atmosphere = 79%
• Problem is getting N2 into a form
that plants can use.
• Most N in soil used for
Agriculture or Sources of
– N
•
•
•
used by plants in cropland=
OM = 37%,
Manure = 19%,
Fixed by soil org.= 19%
Rainfall = 8%,
• Fertilizer = 13%,
• Sewage = 4%.
Steps involved in N2 Cycle
•
•
•
•
•
N2 Fixation
Nitrification
Eutrophication
Ammonification
Denitrification
Nitrogen FixationConversion of N2 into NH3 or R-NH2
A . Non-Biological Fixation
-Air Pollution -The main oxides of nitrogen present in the
atmosphere are nitric oxide (NO), nitrogen dioxide (NO2)
and nitrous oxide – the result of fuel combustion from
motor vehicle exhaust and stationary fuel combustion
sources like electric utilities and industrial boilers--oxides
of nitrogen may remain in the atmosphere for several days
and during this time chemical processes may generate
nitric acid, and nitrates and nitrites as particles.
- Rainfall additions from electrical discharge
(lightning) 2-5 lbs....../acre/year
N2 -----> NO3-
Nitrogen Fixation
Conversion of N2 into NH3 or R-NH2
B. Biological Fixation
1. Non-Symbiotic (independent
organism) - Azotobacter - aerobic &
Clostridium - anaerobic
2. Symbiotic - mutually beneficial for
host organism and bacteria - complex
plant - bacteria interaction
1) Nitrogen Fixation NF can be carried out by symbiotic N fixer and nonsymbiotic N fixer and other natural as well as industrial process.
– Conversion of N2 → NH3
• Symbiotic bacteria, associated with roots of legumes and flowering plants.
eg. Rhizobium which convert N into the organic nitrogen for their own cells.
when these organisms die or leave wastes certain other bacteria and fungi
return the N to the soils and atm.
• Non-symbiotic N fixers are both aerobic and anaerobic bacteria as well as
cyano bacteria. These occur in soil, marine and fresh water.
• Lightening storms convert atm.N into nitrates and reaches the soil through
rain water. They can also be converted to ammonia by denitrifying bacteria.
2) Nitrification
• Conversion of NH3 → NO2 → NO3
• Nitrosomonas convert ammonia to nitrite.
• Nitrobactor converts nitrite to nitrate.
This nitrate is taken up by
higher plants and convert it into protein and nucleic acids.
3) Eutrophication
• Discharge of excess qty of nitrogeneous compds into rivers and lakes can
result excessive growth of algae and macrophytic plants.
4) Ammonification
• Amino acids and nucleotides are broken down into
NH3 or NH4
5) Denitrification
• The reduction of NO3 to N2 .
• Denitrifying bacteria release gaseous nitrogen back in to the atmosphere
2. Nitrification
2 - step process
1. 2NH4+ + 3O2 ---> 2NO2- + 4H+ + 2H20 + E
Nitrosomonas
2. 2NO2- + O2 --> 2NO3- + E
Nitrobacter
Process is acid causing due to release of
4 H+
4. Ammonification
A. Ammonification in the soil is
the conversion of organic N
(RNH2) into inorganic ammonia
(NH3)
heterotrophic organ.
R-NH2 ---> NH3 + H+ ----> NH4+
5. Denitrification
Involves conversion of NO3- to N2 gas
C6H12O6 + 4NO3- --> 6CO2 + 6H2O +
2N2(gas) + NO + NO2
Bacteria = anaerobic
Through nitrification and denitrification 10
- 20 % of the applied N is lost.
Wet & dry
deposition
Atmospheric Nitrogen
Nitrogen fixation by free
living & symbiotic
microbes.
Denitrification
Pseudomonas
Consumers
Detritus
Plants
Litter fall
Uptake
Ammonification
Heterotrophs
Nitrification
Soil ammonia
Nitrosomonas
Soil nitrite
Nitrobacter
Fig.2.11.1 Nitrogen Cycle
Soil nitrate
Oxygen Cycle
Oxygen is the most import. element in our life.
About 21% of Oxygen is present in the atm. As
free O2.
Plants and animals can take the free O2 from the
atm. through a process called respiration, and it
release CO2 and water into the atm.
Oxygen Cycle
CO2
CO2
ATMOSPHERE
PLANTS & ANIMALS
O2
O2
ECOLOGICAL PYRAMIDS
• An”Ecological pyramid” is a graphical representation that
shows the relative amounts of energy or matter
contained within each tropic level in a food chain or food
web.
• An ecological pyramid shows the relationship between
producers and consumers at different tropic levels in an
ecosystem
• There are three ecological pyramids
– Pyramid of Numbers
– Pyramid of Biomass
– Pyramid of Energy
Pyramid of Number
• It is the graphical representation of the no. of
individuals in various trophic levels of food
chain / unit area at any given time.
• In Gross land, Pond eco systems
Producers > Herbivores > Carnivores
– Hence the pyramid is upright
• When the ecosystems contain lesser no. of
producers than those of consumers, the apex
of the pyramid is directed downwards. This
types of pyramids are called Inverted
Pyramids.
Examples of Inverted Pyramid
• Tree Ecosystem
– A single tree harbors many fruit eating birds
(Prim.consumer) and these birds in their turn,
host numerous parasites. (sec.consumer)
Pyramid of Biomass
• It represents the total dry mass (in grams per meter square
of area) of all the organisms in each tropic level at a
particular time.
Inverted Pyramid
Pyramid of Energy
• It represents the rate of energy flow and/or productivity at
successive tropic levels. The pyramids of energy are always
upright. (kcal/m2/year)
E
n
e
r
g
y
Amount of Energy decreases from
Producers
PC
SC
TC
Since the flow of energy is unidirectional, the pyramid energy is UPRIGHT
Ecological Succession
• Natural, gradual changes in the biotic community towards a
stable or climax condition;
• The changes are progressive and predictable.
• The occurrence of sequence of communities over a period of
time in the same area is termed as ES.
• Based on the nature of habitat: primary or secondary.
– Primary – begins in a place without soil
– Secondary – where soil already exists
• Based on the types of organisms.
– Autotrophic Succession
– Heterotrophic Succession
Primary Succession
Pioneer species
• A group of organisms, such as lichens, found in the
primary stage of succession.
Climax community
• A community that has reached a
stable stage of ecological succession
Based on Nature of habitat:
Primary Succession
• PS is defined as the initial establishment and
development of an ecosystem which occurs on a site
previously unoccupied by living organism.
• The organisms that establish their first are called
“Pioneer organisms” / Primary colonizers.
• Simple plants first.
• Gradual arrival of more complicated and larger plants as
the habitat changes
• Unfavorable for life at first.
• Ends with a “climax community” – ecosystem stays
constant, provided there are no changes in abiotic
influences.
Secondary Succession
Secondary Succession
• Community development in the previously occupied areas is
replaced by other community.
• If successions starts on an area, previously colonized, and the
soil is organically enriched, it is known as SS.
• SS is defined as the reestablishment of a new ecosystem at a
site where community was existing earlier but disrupted by
natural or artificial means like storm, fire, flood or human
activities.
• E.g., loss of trees after disease, Fire or wind, deforestation etc.
• More rapid than primary succession.
Primary Vs Secondary
• No soil.
• Pioneer species.
• Weathering &
decomposition
• End = Climax
community.
• Soil already exists.
• Seeds have suitable soil
conditions.
• Occurs much faster.
• Climax community.
Based on types of Organisms
• Autotrophic Succession:
The succession where initially the green plants are
much greater in quantity than the animals, is known as
autotrophic succession. Such a succession takes place
in a medium rich in inorganic substances. Since there
are green plants, there is gradual increase in the
organic matter and energy flow in the ecosystem.
• Heterotrophic Succession:
On the other hand, in heterotrophic succession, the
populations of heterotrophic organisms, like bacteria,
actinomycetes, and fungi are present in greater
quantity in the initial stage. This is found in organic
habitats.
Process of Succession
1.
2.
3.
4.
5.
6.
7.
8.
Nudation
Invasion
Migration
Colonisation
Ecesis
Aggregation
Competition and reaction
Climax or stabilization
Process of Succession
1. Nudation: The process of formation of a bare
area is known as Nudation
• Caution
– Industrial / Agricultural – Manmade
– Climatic Change
– Biotic disturbances – Natural
• Landslides
• Floods
Process of Succession
2. Invasion: The process of successful
establishment of new species in the bare area is
known as Invasion
3. Migration: The process of movement of
organisms in to the bare area is known as
Migration.
The seeds, spores of the species invade (enter by
force) to the bare area by the agents such as Air
and Water.
Process of Succession
4. Colonisation: Occupation of the bare area by
first or pioneer community is called colonisation
5. Ecesis: After reaching the bare area, the new
species starts to establish themselves in it.
Establishment of pioneer community is called
Ecesis. Such pioneer reacts with the medium like
soil or water and establishes themselves.
Process of Succession
6. Aggregation: The final stage of Invasion by a
Pioneer group is called Aggregation. The species
which has successfully settled in the new area,
reproduce and aggregate into large population in the
new area.
7. Competition and Reaction: After establishment,
various species compete among themselves for
space, light and nutrients. Communities which
cannot withstand during competition, are replaced
by other communities till a climax community is
established.
Process of Succession
8. Stabilization: This is the final stage in the process
of ecological succession. The climax community
becomes more or less stabilized for a long period of
time. It can maintain itself in equilibrium with the
climate of that area.