Carbon Cycle



The Carbon Cycle:
The Carbon Cycle is the biogeochemical cycle by which carbon is exchanged between the Biosphere, Geosphere, hydrosphere, and atmosphere of the earth.


Figure 1-1:
carbon_cycle_NASA.jpg
The Carbon Cycle

Source: http://earthobservatory.nasa.gov/Library/CarbonCycle/carbon_cycle4.html


Four main types of processes move carbon through its cycle:
  • Biological processes, such as photosynthesis, respiration, and decomposition, take up and release carbon and oxygen.
  • Geochemical processes, such as erosion and volcanic activity, release carbon dioxide to the atmosphere and oceans.
  • Mixed biogeochemical processes, such as the burial and decomposition of dead organisms and their conversion under pressure into coal and petroleum (Fossil fuels), store carbon underground.
  • Human activities, such as mining, cutting and burning forests, and burning fossil fuels, release carbon dioxide into the atmosphere.

Figure 1-1:

This shows how these processes move carbon through the biosphere. Carbon Dioxide is released by volcanic activity, respiration, human activities such as burning of fossil fuels and vegetation, and by the decomposition of organic matter. Plants take in carbon dioxide and use the carbon to build carbohydrates during photosynthesis. It's passed passed along food webs to animals and other consumers. Eventually these compounds break down and the carbon returns to the atmosphere.