Nitrification


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Related to Nitrification: Nitrifying bacteria, nitrogen cycle

nitrification

[‚nī·trə·fə′kā·shən]
(microbiology)
Formation of nitrous and nitric acids or salts by oxidation of the nitrogen in ammonia; specifically, oxidation of ammonium salts to nitrites and oxidation of nitrites to nitrates by certain bacteria.

Nitrification

 

the microbiological conversion of ammonium salts to nitrates, the main form of nutrient nitrogen for plants. Nitrification takes place in the soil and in bodies of water. It is the final stage of the mineralization of organic nitrogen compounds, which begins with ammonification, and it is an index of soil fertility. The process is caused by chemosynthesizing nitrifying bacteria.

Nitrification proceeds in two stages. An ammonium ion is oxidized to a nitrite ion by bacteria of the first stage, and then the nitrite ion is oxidized to a nitrate ion by bacteria of the second stage. Nitrification takes place at a soil pH of 5–9 and is carried out by aerobic organisms. An insufficiency of air in the soil leads to cessation of nitrification. Proper soil management improves aeration, thus intensifying nitrification.

As a result of the increasing combustion of fuel in industrial plants and internal-combustion engines, nitrogen oxides are formed in the atmosphere and are deposited in large amounts in the soil and in the water of reservoirs with rainfall. They are then converted to nitrates by the action of nitrifying bacteria. The excess concentration of nitrates in water makes it unsuitable for drinking. To prevent large-scale formation of nitrates in water, chemical preparations that prevent nitrification in the soil are sometimes used.

G. A. ZAVARZIN

References in periodicals archive ?
Since the air-diffuser position resulted in the formation of aerobic or anoxic zone, the performance of nitrogen removal through SND might be compared to the separated reactions of nitrification and denitrification.
Although microbial processes such as nitrification are enhanced with liming (e.
Using slowrelease fertilizer and nitrification inhibitors, as well as puddling of paddy fields are recommended to mitigate nitrate leaching.
Inhibition of nitrification has been reported for systems in sandy soils with less than 45 cm separation from the water table (Humphrey et al.
The rate of nitrification in the environment is dependent on multiple factors including the biological community, dissolved organic carbon (DOC), temperature, dissolved oxygen (DO), and pH (Kemp and Dodds 2001; Strauss et al.
2005) in order to determine the nitrification and denitrification rate simultaneously.
This fast and energy efficient mixing process pushes and pulls water up into the tank and breaks up stagnant water layers to prevent the formation of thermoclines and helps reduce nitrification.
The company is introducing their new system to industries that want to achieve continuous flow, intermittent cleaning, BOD/COD removal, nitrification and all of the benefits of traditional MBBR's but with additional capabilities.
A potent greenhouse gas, nitrous oxide is produced in riverbed sediments through nitrification and denitrification.
Soils near the road tended to have lower N mineralization and nitrification rates.
Ammonia oxidation is the primary step in the oxidation of ammonia to nitrate via nitrite and is thought to be the rate-limiting step of nitrification in most systems, it is therefore central to the global nitrogen (N) cycle (Kowalchuk & Stephen, 2001).
2]0 emissions result from the biological processes of nitrification and denitrification.