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• Earth’s mantle and crust.
• Living and non-living marine biota.
• Oceans.
• Terrestrial biosphere.
• The sediments.
The carbon exchanges between carbon reservoirs occur by chemical, physical,
geological, and biological processes.
6
6
6
2
2
6 12 6
2
CO
H O
C H O
O
Light
+
→
+
Carbon in the earth’s atmosphere exists mostly as methane and carbon dioxide.
Apart from these compounds, carbon also exists as soot, smoke, dust, and variety of
other chemicals. Carbon dioxide is converted into glucose and oxygen by
photosynthesis.
Human activity by combustion of fuel, manufacturing, waste disposal, mining,
etc. has hugely added carbon compounds to the atmosphere.
Photosynthesis traps carbon dioxide and turns it into glucose, which is further
converted into biomass. Animals that feed on plants will pass on the carbon along
the food chain. Decay of waste excreted by living organisms and dead living organEvapotranspiration
Evaporation
Runoff
Absorption by plants
Infiltration to ground water
Urban
Use
Precipitatio
n
Fig. 1.21 Water cycle
1 Fundamentals of Chemistry for Environmental and Medical Professionals