Name_____________________________________ Date_______________ Period______
Biogeochemical Cycling – Movement of matter from one organism to another and from
living organisms to the abiotic environment and back again.
The Carbon Cycle
The global movement of carbon between the biotic and the abiotic environment.
Carbon is present in the atmosphere as carbon dioxide (CO2).
Carbon is present in the ocean as carbonate and bicarbonate (CO32-, HCO3-).
Carbon is present in sedimentary rock as calcium carbonate (CaCO3).
Carbon is present in living things as proteins, carbohydrates, and other molecules essential to life.
Carbon makes up approximately 0.04% of the atmosphere as a gas. What are the two major gases in
the atmosphere and their percentages?
Carbon primarily cycles through biotic and abiotic environments via photosynthesis, cellular
respiration and combustion (CO2).
Photosynthesis (6CO2 + 6H2O → C6H12O6 + 6O2) incorporates carbon from the abiotic environment (CO2
in the atmosphere) into the biological compounds of producers (sugars).
Producers, consumers and decomposers use sugars for energy and return CO2 to the atmosphere in a
process called cellular respiration (C6H12O6 + 6 O2 → 6 CO2 + 6 H2O).
Carbon present in plants such as wood, swamp vegetation that may form coal, or shells of microscopic
marine organisms that may form oil and natural gas is returned to the atmosphere by the process
of combustion (burning).
The carbon-silicate cycle (which occurs on a geological timescale involving millions of years; ex. ocean
sediment turns to limestone) which returns CO2 to the atmosphere through volcanic eruptions
(limestone gets subducted via plate tectonics) and both chemical and physical weathering processes.
Carbon also cycles through the biotic and abiotic environments in the oceans.
Photosynthesis and cellular respiration also occur in marine organisms.
CO2 from the atmosphere mixes with the surface of the ocean, dissolving carbon into the ocean water
in the form of carbonate.
Marine organisms take carbonate from the ocean water to make their shells. The shells then settle to
the ocean floor as sediment.
Most ocean sediment forms the sedimentary rock limestone. Some sediment may transform into
petroleum and natural gas if no oxygen is present.
Carbon present in oil and natural gas is returned to the atmosphere by the process of combustion
(burning).
Humans alter the carbon cycle by adding excess CO2 to the atmosphere through:
Burning fossil fuels
Clearing vegetation faster than it is replaced
Carbon Reservoir
Processes that move Carbon
Atmosphere
photosynthesis
Atmosphere
dissolved
Terrestrial life
respiration (exhaled into gas)
Terrestrial life
fallen/Decomposition
Terrestrial life
combustion/burned
Soil/detritus (plant
matter)
decay (transform to gas)
Soil/detritus (plant
matter)
runoff
Soil/detritus (plant
matter)
buried
Surface ocean
come out of solution (liquid to gas)
Surface ocean
ocean mixing (waves and currents)
Surface ocean
photosynthesis
Intermediate/ Deep
ocean
settle (sink)
Intermediate/ Deep
ocean
ocean mixing (waves and currents)
Marine life
respiration (exhaled into gas)
Marine life
settle (sink)
Ocean sediment
compression (in oxygen free
environment)
Ocean sediment
compaction & cementation
Ocean sediment
volcanic eruption
Fossil fuel
combustion (burn)
New Carbon Reservoir
1. Define carbon cycle:
2. Define reservoir:
3. Define biotic:
4. List the biotic reservoirs in the carbon cycle. Give examples of what each reservoir is composed of or what
types of things may be found in each reservoir. Maybe make a table.
5. Define abiotic:
6. List the abiotic reservoirs in the carbon cycle. Give examples of what each reservoir is composed of or
what types of things may be found in each reservoir. Maybe make a table.
7. Define combustion and give two examples of things that can be combusted.
8. What process have humans increased tremendously since the industrial revolution?
9. Because of this process, carbon is being moved from which reservoir to which reservoir?
10. What environmental problem is this causing for us?
11. Match the following reservoirs to the proper form of carbon.
Atmosphere
Ocean Water
All Living Things
Seashells and Sedimentary Rock
_____________________________________: carbon in calcium carbonate (CaCO3)
_____________________________________: carbon in carbonate and bicarbonate (CO32-, HCO3-)
_____________________________________: carbon in proteins and carbohydrates
_____________________________________: carbon in carbon dioxide (CO2)
12. The composition of our atmosphere:

______% ____________________ and ______% ___________________ = 99% of the gases in
our atmosphere

What gas makes up approximately 0.04% of the gases in our atmosphere? __________________
Name___________________________ Date___________ Period______ #_____
CARBON CYCLE DIAGRAM