Carbon Cycle

Carbon

Carbon exists in the nonliving environment as:

• Carbon dioxide (CO2)• Carbonic acid ( HCO3

−)

• Carbonate rocks (limestone and coral = CaCO3)

• Deposits of Fossil fuels• Dead organic matter

Organic Carbon

• Hydrocarbons: CH4

• Carbohydrate: CH2O

Inorganic carbon

• Carbon Dioxide: CO2

• Calcium Carbonate: CaCO3

Mandale Limestone Quarry

Carbon reservoirs

Carbon reservoirs

•The atmosphere.

•The biosphere (include fresh water systems and non-living organic material, such as soil carbon).

•The oceans ( including dissolved inorganic carbon and living and non-living marine biota).

•The lithosphere (sediments, Earth core including fossil fuels).

Carbon Cycle

Carbon is released into the atmosphere in several ways

• Respiration by plants and animals.

• Decay of animal and plant matter.

• Combustion of organic material

• Production of cement.

• The ocean releases CO2 into the atmosphere. • Volcanic eruptions and metamorphism

Carbon is taken from the atmosphere in several ways

• Photosynthesis. • The oceans when the seawater becomes

cooler, more CO2 dissolve and become carbonic acid.

• In the upper ocean areas organisms convert reduced carbon to tissues, or carbonates.

Photosynthesis

• CO2 + H2O + sunlight CH2O + O2

Respiration

• CH2O + O2 CO2 + H2O + energy

Combustion or Oxidization of hydrocarbon

CH4 + 2 O2 CO2 + 2 H2O + energy

Human Impacts on the Carbon Cycle

Burning fossil fuels have serious impact on the carbon cycle.

Fossil Fuel

86% of global primary energy consumption is fossil fuels.

Fossil Fuels

•Petroleum•Natural Gas•Coal

CO2 Concentration

Pre-Industrial value: 280 ppm (600 billion tons)Current value: 380 ppm (800 billion tons)Critical value: 560 ppm (1200 billion tons)

Keeling Curve