Carbon Cycling in the Environment

Primary Producers in the Carbon Cycle

• Primary producers are organisms that make their own food through photosynthesis (plants, algae, and some bacteria).
• They take in carbon dioxide from the atmosphere and convert it into organic molecules, such as sugars.

Residence Time of Carbon

• Residence time is the average amount of time that a carbon atom spends in a particular reservoir.
• Carbon in living organisms has a relatively short residence time (years to decades).
• Carbon in fossil fuels has a much longer residence time (millions of years).

Reservoirs of Carbon

• Two largest reservoirs of carbon on Earth:
  • The lithosphere (rocks) holds the most carbon.
  • The ocean holds the second largest amount.

Source of Carbon in Living Organisms

• The primary source of carbon in all living organisms is carbon dioxide (CO2).

Fossil Fuel Formation

• Fossil fuels are formed over millions of years from the remains of ancient organisms.
• These organisms are buried under layers of sediment and subjected to heat and pressure.
• This process converts the organic matter into coal, oil, and natural gas.