Monday, June 23, 2014

Biogeochemical cycles - Carbon cycle in brief

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 

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
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   + H2O  + sunlight   =>  CH2O  + O2

CH2O  + O2   =>  CO2   + H2O  + energy

Human Impacts on the Carbon Cycle => Combustion or Oxidization of hydrocarbon
86% of global primary energy consumption is fossil fuels.

Fossil Fuels
Natural Gas

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

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