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
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 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.
CO2 Concentration
Pre-Industrial value: 280 ppm (600 billion tons)Current value: 380 ppm (800 billion tons)Critical value: 560 ppm (1200 billion tons)