Carbon Cycle
 Exchange of carbon between environment & living
things.
 All living organisms contain carbon
 Plants use CO2 from air to make food through
photosynthesis.
 Animals get carbon by eating plants.
 Carbon returns to environment through respiration,
decomposition, or combustion.
Carbon Cycle
Carbon Pools
Pool
Atmosphere
Terrestrial Plants
Soil Organic matter
Ocean
Fossil Fuel Deposits
Marine Sediments and Sedimentary Rocks
Amount in Billions of Met ric Tons
578 (as of 1700) - 766 (a s of 1999)
540 to 610
1500 to 1600
38,000 to 40,000
4000
66,000,000 to 100,000,000
Carbon is stored on our planet in the following major pools:
• as organic molecules in living and dead organisms found in the
biosphere;
• as the gas carbon dioxide in the atmosphere;
• as organic matter in soils;
• in the lithosphere as fossil fuels and sedimentary rock deposits such as
limestone, dolomite and chalk;
• in the oceans as dissolved atmospheric carbon dioxide and as calcium
carbonate shells in marine organisms.
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Global Carbon Cycle
Carbon is exchanged between the active pools due to
various processes such as
photosynthesis and cellular respiration between the
land and the atmosphere, and
diffusion between the ocean and the atmosphere.
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Plants & The Carbon Cycle
• Plants take in carbon dioxide
and convert it to sugar which
can be stored until used for
energy.
• This process is called
photosynthesis.
• Photosynthesis= Energy
(sun)+ Water+ Carbon
dioxide Glucose+ Oxygen
Plants & The Carbon Cycle
• Plants release small amounts of
carbon dioxide as a waste
product when they convert
their stored sugar to chemical
energy (ATP).
• Plants need ATP for growth &
reproduction.
• This process is called cellular
respiration.
Cellular Respiration:
C6H12O6 + O2 - CO2
+ H2O + energy
Animals & The Carbon Cycle
• Animals eat carbon
contained in animal and
plant tissues and release
carbon dioxide as a waste
product.
• This process is cellular
respiration.
Cellular Respiration:
C6H12O6 + O2 - CO2
+ H2O + energy
Decay & The Carbon Cycle:
• Decomposers release the
carbon from dead plant and
animal tissues back into the
atmosphere.
Fossil Fuels & The Carbon Cycle:
• Over millions
of years fossil
fuels may form
from the
buried remains
of plants and
animals.
Fossil Fuels & The Carbon Cycle:
• This carbon
reenters the
atmosphere
during
combustion
(burning).
The Oceans & The Carbon Cycle:
• Dissolved
carbon
dioxide in
sea water
becomes
deposited as
calcium
carbonate
shells.
The Oceans & The Carbon Cycle:
• Over millions
of years,
these shells
form
sedimentary
rock.
• Ocean deposits are the
biggest sink of carbon
on the planet.
• The Rock Cycle
ultimately releases
carbon stored in
sedimentary rock.
Explore
Carbon Cycle
• Use the diagram from the website to
examine the elements of the carbon
cycle.