Denitrification

Denitrification is a microbially facilitated process of nitrate reduction that may ultimately produce molecular nitrogen (N2) through a series of intermediate gaseous nitrogen oxide products. This respiratory process reduces oxidized forms of nitrogen in response to the oxidation of an electron donor such as organic matter. The preferred nitrogen electron acceptors in order of most to least thermodynamically favorable include nitrate (NO3−), nitrite (NO2−), nitric oxide (NO), nitrous oxide (N2O) finally resulting in the production of dinitrogen (N2) completing the nitrogen cycle.

Process

Denitrification takes place under special conditions in both terrestrial and marine ecosystems. In general, it occurs where oxygen, a more energetically favourable electron acceptor, is depleted, and bacteria respire nitrate as a substitute. Due to denitrification, nitrate-rich water can be deprived of nitrate if it comes into contact with organic material under anoxic conditions.

Environmental Impact

Denitrification processes are responsible for the production and consumption of nitrous oxide (N2O), a major greenhouse gas and stratospheric ozone-depleting substance. It is also responsible for significant losses of nitrogen from agricultural soils, which can lead to reduced agricultural productivity.

Role in Nitrogen Cycle

Denitrification is a key process in the nitrogen cycle, the circulation of nitrogen among the atmosphere, land, and oceans. Nitrogen exists in a variety of forms in these systems, including both inorganic forms, such as ammonium, nitrite, nitrate, and nitrous oxide, and organic forms, such as amino acids and DNA.

See Also

• Nitrogen Cycle
• Nitrate Reduction
• Nitrogen
• Nitrous Oxide

References

Denitrification Resources
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