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Chemical Cycling
Chemical Cycling
Biogeochemical cycles: the various nutrient
circuits, which involve both abiotic and
biotic components of an ecosystem
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Water
Carbon
Nitrogen
(Phosphorous)
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Nitrogen Cycle
• Nitrogen enters the atmosphere, in gaseous form
N2. It has to be transformed into a usable form for
organisms to use.
• Nitrogen fixing bacteria convert N2 into NH4 in a
process called nitrogen fixation.
• NH4 is also produced by decomposers when
breaking down organic matter in a process called
ammonification.
• Different bacteria take NH4 and covert it into nitrite
(NO2-) and nitrate (NO3-) in a process called
nitrification. (This allows producers to use the
nitrogen now, assimilation)
• Denitrifying bacteria convert nitrate (NO3-) back
to N2 for release back into the atmosphere.