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Eco System
M. Subramanian
Assistant Professor
Department of Chemical Engineering
Sri Sivasubramaniya Nadar College of Engineering
Kalavaam ! "#$ %%#& Kanchipuram 'Dist(
)amil Nadu& *ndia
msubbu.in+A),gmail.com
20-July-2009
GE 2211 Environmental Science and Engineering
Unit II
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Contents
- Concept of an ecosystem ! structure and function of anecosystem ! producers& consumers and decomposers !energy flo in the ecosystem ! ecological succession ! foodchains& food ebs and ecological pyramids
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*ntroduction
- An ecosystem can be defined as the basic
functional unit of nature& including both biotic'living( and abiotic 'nonliving( constituents.! a pond& a forest& an estuary& a grassland
- Abiotic components/ air& roc& and ater are thebasic components
- 0iotic components/ classified according to thefunction of the particular organism. )here arethree groups/! producers& consumers& and decomposers.
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Estuary
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Grassland20-July-2009 M Subramanian
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Ecosystems are not isolated from one another. Oneecosystem blends into the next through a transitional region,an ecotone, which contains many species common to the twoadjacent systems.
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Producers
- Producers! the green plants such as grasses and trees
! are so called because they are capable of producingtheir on food from the abiotic environment
- Producers create organic molecules proteins& lipids andcarbohydrates1 by capturing light energy and combining thecaptured energy ith inorganic molecules
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Consumers
- Consumers! organisms that are incapable of producing their on food and
that must use 'consume( other organisms for their food! all animals fall into this category.
! consumers feed on producers and ould not e2ist ithoutproducers.
- )hree types of consumers/! herbivores& hich eat plants 'producers(3
! carnivores& hich eat animals ! either herbivores or othercarnivores3
! omnivores& hich are both herbivorous and carnivorous.
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Decomposers
- Decomposers ! also called microconsumers& includebacteria& fungi& and some of the small invertebrates
'animals ithout bacbones & eg/ orms(.
- 4ie consumers& these organisms cannot produce their onfood3 but unlie consumers& they obtain their food energyby breaing don dead plants and animals to their basiccomponents& thereby releasing these substances bac intothe abiotic portions of the environment.
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5ood Chain
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5ood Chain in a Marine Ecosystem
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5ood 6ebs
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Marine 5ood 6eb
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Ecological Pyramid
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Ecological Succession
- Ecological succession is the gradual process by hichecosystems change and develop over time. Nothing
remains the same and habitats are constantly changing.
- Succession taes place because the environmentalconditions in a particular place change over time.
- Each species is adapted to thrive and compete best againstother species under a very specific set of environmentalconditions. *f these conditions change& then the e2istingspecies ill be replaced by a ne set of species hich are
better adapted to the ne conditions.
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Energy 5lo and Materials Cycling
The movement of nutrients (blue arrows) and energy (redarrows) and both (brown arrows) through the ecosystem.20-July-2009 M Subramanian
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Energy 5lo in Ecosystem
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Energy 5lo in Ecosystem
- Almost all life re7uires the energy that flos daily from the
sun.
- )he basic conversion of this solar energy to usable formtaes place through plant material on land and in ater.
- As the energy passes from plants to hatever eats them&and in turn eats the eaters of the plants& some is lost asheat& and eventually it all is.
- )hus& energy doesn8t cycle3 it flos through the ecosystemuntil it8s used up.
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6ater Cycle
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Mineral Cycle
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Carbon Cycle
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CO2
PRODUCERS
taken up during
photosynthesis
1st CONSUMERS
2nd CONSUMERS
3rd CONSUMERS
DECOMPOSERS
Cellular respiration
releases
Food web subcycle
Decomposition releases
C compounds into soil
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Fossil fuel
subcycle
CO2
FOOD WEB
SUBCYCLE
dead organisms buried
by sediment become
FOSSIL FUELS
Cellular respiration
releases photosynthesisBurning
releases
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CO2
FOOD WEB
SUBCYCLE
dead organisms buried
by sediment become
FOSSIL FUELS
Cellular respiration
releases photosynthesisBurning
of fossil fuels
increases CO2levels
shells and skeletons of marine
organisms deposited and
compressed to become
CARBONATE ROCKSDecompose (weather)
into bicarbonate ion (HCO3-
)
further decomposition
produces
Ion in water enters
Where human activities change the cycling rate of carbon
among reservoirs.
Removal of vegetation
(trees) prevents CO2
from being removedfrom the atmosphere
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Carbon Cycle
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Nitrogen Cycle
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Atmosphere
N2 (g)
Soil moisture
dissolves in
Dissolved N2
absorbed by
N-fixing bacteriaLeguminous bacteria
Legumes (plants)
symbiosisNO
3
-- released in roots,
absorbed by
Nitrifying bacteria
NH3absorbed by
Consumers
Organic nitrogen
ingested by NH3 produced as
waste from breakdown
of proteins
All plants
NO3-- in soilabsorbed by
Denitrifying bacteria
(under anaerobic
conditions)
N2 (g)
released into
Atmospheric fixation
generates nitric acid(HNO3)
HNO3 dissociates in
soil
Nitrogen Cycle
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Phosphorus Cycle
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