Transcript Cycles in an Ecosystem

Cycles in an Ecosystem
Water, Carbon, and
Nitrogen
Carbon, Nitrogen, and Water
• Each is essential to living things.
• Why do we need each one?
The Water Cycle
• Earth is considered the WATER planet.
• Water covers about 70% of its surface.
– Also our bodies are about 65% water
• We can’t live without it.
Water
• Earth’s water supply is finite
– The same amount of water that is here now is
the same amount of when the dinosaurs
roamed the earth.
Oceans
They are the GREATEST reservoirs of water
on the planet.
What happens??
• Energy from the sunlight,
– water evaporates, from surface water,
– rises into the atmosphere as a gas called
water vapor.
• In the atmosphere
– Water vapor cools
– Condenses into a liquid
– Formation of cloud Droplets
What happens Continued
• Cloud droplets: If they continue to grow
– They become precipitation
• Which returns to earth
– Often falling directly back into the ocean or
surface water
– Or on land where it seeps directly into soil or
washes over the surface and enters bodies of
water, as a runoff.
Water Runoff
The Carbon Cycle
• Once you understand the water cycle the
carbon cycle is relatively simple.
• Carbon is considered the building block of
life.
Uses for Carbon
• Essential for DNA, proteins, fats, carbs
and many more substances
• Used for food and gives energy which
living things need.
• Carbon is a form of carbon
dioxide=greenhouse gas (maintains heat).
Where carbon is found.
• The ocean
• Atmosphere
• Rocks
– When carbon leaves these reservoirs, it
cycles through the environment in several
CONNECTED ways.
In ONE Part of the CYCLE
• Carbon moves between the atmosphere,
ocean, and living things.
– Plants use carbon dioxide in photosynthesis
to make sugars and other organic chemicals.
– Consumers eat both plants and animals that
eat plants via food web = intake of Carbon.
– Respiration releases Carbon into Atmosphere.
– The decomposition of living organisms
releases CO2 in the soil, water, and air.
In ANOTHER Part of the C. Cycle
• In book:
– Shells of marine animals (contain carbon), fall
to the bottom of the ocean
– The decompose the shells pile up and are
covered by sediment--- over long periods of
time turn to rock.
– Millions of years go by seafloor becomes dry
land---Erosion dissolves carbon containing
minerals
– Returning Carbon into the atmosphere.
Third Pathway:
Burning of Fossil Fuels
• Oil and Natural gas form from the remains
of dead organisms (CO2 and H2)
– Covered by layers of sediment
• Compaction and Chemical changes take place
• Turns into Petroleum. (Millions of yrs later)
• When we burn Oil and Gas it is releasing
Carbon back in the atmosphere again.
Problems
• People are altering because of
Deforestation and Burning of Fossil Fuels.
– Increase in CO2 in the air
• Might be one of the causes of global warming
Nitrogen Cycle
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A major component of Amino Acids (proteins)
Major chemical of the atmosphere (78%)
Paradox: Nitrogen by itself is not useable by
most organisms.
Must be “fixed” to be useful to biological
forms
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NH3, NO2, or NO3
Fixations: Nitrogen combines with
Oxygen=Nitrate
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High Energy= Lightning N2 with
H1O=Ammonia Nitrate Produced (usable)
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Biological Fixation: Microbe Mediation
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Bacteria that live in roots of legume plants.
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Clover, peas, soybeans, and alfalfa.
Bacteria converts gas N2 to ammonia-> nitrate.
Plants=Nitrogen Cycle Component
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Plants use ammonia, nitrate, and absorbed
nutrients from the soil to make proteins.
How do we get it?
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We eat the plants .. This is the only way we
can get Nitrogen!!
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Nitrogen can also move through and
ecosystem by trophic levels just like Carbon.
The last step in cycle
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Decomposition: bacteria break down organic
compounds (such as proteins) into simple N2
containing compounds
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Denitrifying bacteria in soil act on ammonia ,
simplifying into H2 and N2.
Which then releases N2 gas back into soil and
atmosphere.
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Problems:
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Humans: Burning of F.Fuels and using N2
fertilizers.
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Responsible for : Acid rain, pollution in water
systems in agricultural areas, and formation of
algae blooms.
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Rob bodies of water of O2.