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Nitrification

 
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Nitrification
 
 
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Nitrification is the biological oxidation
Redox

Redox describes all chemical reactions in which atoms have their oxidation number changed.This can be either a simple redox process such as the oxidation of carbon to yield carbon dioxide or the reduction of carbon by hydrogen to yield methane , or it can be a complex process such as the oxidation of sugar in the human body through a ser...
 of ammonia
Ammonia

Ammonia is a chemical compound with the chemical formula nitrogenhydrogen. It is normally encountered as a gas with a characteristic pungent odor....
 with oxygen into nitrite
Nitrite

The nitrite ion is NO2-. The anion is bent, being isoelectronic with ozone. More generally, a nitrite compound is either a Salt or an ester of nitrous acid....
 followed by the oxidation of these nitrites into nitrate
Nitrate

In inorganic chemistry, a nitrate is a salt of nitric acid with an ion composed of one nitrogen and three oxygen atoms . In organic chemistry the esters of nitric acid and various alcohols are called nitrates....
s. Degradation of ammonia to nitrite is usually the rate limiting step of nitrification. Nitrification is an important step in the nitrogen cycle
Nitrogen cycle

The nitrogen cycle is the biogeochemical cycle that describes the transformations of nitrogen and nitrogen-containing compounds in nature. It is a cycle which includes Gas components....
 in soil
Soil

Soil is the naturally occurring, unconsolidated or loose covering on the Earth's surface. Soil is composed of particles of broken rock that have been altered by chemical and environmental processes including weathering and erosion....
.






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Nitrogen Cycle
Nitrification is the biological oxidation
Redox

Redox describes all chemical reactions in which atoms have their oxidation number changed.This can be either a simple redox process such as the oxidation of carbon to yield carbon dioxide or the reduction of carbon by hydrogen to yield methane , or it can be a complex process such as the oxidation of sugar in the human body through a ser...
 of ammonia
Ammonia

Ammonia is a chemical compound with the chemical formula nitrogenhydrogen. It is normally encountered as a gas with a characteristic pungent odor....
 with oxygen into nitrite
Nitrite

The nitrite ion is NO2-. The anion is bent, being isoelectronic with ozone. More generally, a nitrite compound is either a Salt or an ester of nitrous acid....
 followed by the oxidation of these nitrites into nitrate
Nitrate

In inorganic chemistry, a nitrate is a salt of nitric acid with an ion composed of one nitrogen and three oxygen atoms . In organic chemistry the esters of nitric acid and various alcohols are called nitrates....
s. Degradation of ammonia to nitrite is usually the rate limiting step of nitrification. Nitrification is an important step in the nitrogen cycle
Nitrogen cycle

The nitrogen cycle is the biogeochemical cycle that describes the transformations of nitrogen and nitrogen-containing compounds in nature. It is a cycle which includes Gas components....
 in soil
Soil

Soil is the naturally occurring, unconsolidated or loose covering on the Earth's surface. Soil is composed of particles of broken rock that have been altered by chemical and environmental processes including weathering and erosion....
. This process was discovered by the Russia
Russia

Russia , or the Russian Federation , is a list of countries spanning more than one continent country extending over much of northern Eurasia....
n microbiologist
Microbiologist

A microbiologist is a scientist who works in the field of microbiology. Most have a university degree in the subject.Specialists in the broad field of microbiology include:...
, Sergei Winogradsky
Sergei Winogradsky

Sergei Nikolaievich Winogradsky was a Russian microbiologist, ecologist and soil science who pioneered the Biogeochemical cycle concept and discovered the biological process of nitrification, the first known form of chemoautotrophy....
.

The oxidation of ammonia into nitrite is performed by two groups of organisms, ammonia oxidizing bacteria
Bacteria

The Bacteria are a large group of unicellular microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals....
 and ammonia oxidizing archaea
Archaea

The Archaea are a group of single-celled microorganisms. A single individual or species from this domain is called an archaeon . Archaea, like bacteria, are prokaryotic....
. Ammonia oxidizing bacteria can be found among the ß- and ?-proteobacteria . In soils the most studied ammonia oxidizing bacteria belong to the genera Nitrosomonas
Nitrosomonas

Nitrosomonas is a genus comprising of rod shaped chemoautotrophic bacteria.This rare bacteria oxidizes ammonia into nitrite as a metabolic process....
 and Nitrosococcus. Although in soils ammonia oxidation occurs by both bacteria and archaea, archaeal ammonia oxidizers dominate in both soils and marine environments, suggesting that Crenarchaeota
Crenarchaeota

In alpha taxonomy, the Crenarchaeota are a phylum of the Archaea. Initially, the Crenarchaeota were thought to be extremophiles but recent studies have identified them as the most abundant archaea in the marine environment....
 may be greater contributors to ammonia oxidation in these environments. The second step (oxidation of nitrite into nitrate) is (mainly) done by bacteria of the genus Nitrobacter
Nitrobacter

Nitrobacter is genus of mostly rod-shaped, gram-negative, and chemoautotrophic bacteria.Nitrobacter plays an important role in nitrogen cycle by oxidizing nitrite into nitrate in soil....
. Both steps are producing energy to be coupled to ATP synthesis. Nitrifying organisms are chemoautotroph
Chemotroph

Chemotrophs are organisms that obtain energy by the oxidation of electron donating molecules in their environments. These molecules can be organic molecule or inorganic ....
s, and use carbon dioxide
Carbon dioxide

Carbon dioxide is a chemical compound composed of two oxygen atoms covalent bond to a single carbon atom. It is a gas at standard temperature and pressure and exists in Earth's atmosphere in this state....
 as their carbon
Carbon

Carbon is a chemical element with chemical symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalence?making four electrons available to form covalent bond chemical bonds....
 source for growth.

Nitrification also plays an important role in the removal of nitrogen
Nitrogen

Nitrogen is a chemical element that has the symbol N and atomic number 7 and atomic mass 14.00674?. Elemental nitrogen is a colorless, odorless, tasteless and mostly inert diatomic gas at standard conditions, constituting 78% by volume of Earth's atmosphere....
 from municipal wastewater
Wastewater

Wastewater is any water that has been adversely affected in quality by anthropogenic influence. It comprises liquid waste discharged by domestic residences, commercial properties, industry, and/or agriculture and can encompass a wide range of potential contaminants and concentrations....
. The conventional removal is nitrification, followed by denitrification
Denitrification

Denitrification is a microbially facilitated process of dissimilatory nitrate reduction that may ultimately produce molecular nitrogen through a series of intermediate gaseous nitrogen oxide products....
. The cost of this process resides mainly in aeration
Aeration

Aeration is the process by which air is circulated through, mixed with or solvation in a liquid or substance....
 (bringing oxygen in the reactor) and the addition of an external carbon source (e.g. methanol
Methanol

Methanol, also known as methyl alcohol, carbinol, wood alcohol, wood naphtha or wood spirits, is a chemical compound with chemical formula carbonhydrogen3oxygenhydrogen ....
) for the denitrification.

In most environments both organisms are found together, yielding nitrate as the final product. It is possible however to design systems in which selectively nitrite is formed (the Sharon process).

Together with ammonification
Ammonification

Ammonification is a term used in biology to describe the process by which decomposers change nitrogen in detritus to ammonium . ...
, nitrification forms a mineralization
Mineralization (soil)

Mineralization in soil science, is when the elements in organic matter decomposes into plant accessible forms, for example by nitrification. Mineralization is the alternative to immobilization....
 process which refers to the complete decomposition of organic material, with the release of available nitrogen compounds. This replenishes the nitrogen cycle
Nitrogen cycle

The nitrogen cycle is the biogeochemical cycle that describes the transformations of nitrogen and nitrogen-containing compounds in nature. It is a cycle which includes Gas components....
.

Chemistry

Nitrification is a process of nitrogen compound oxidation
Redox

Redox describes all chemical reactions in which atoms have their oxidation number changed.This can be either a simple redox process such as the oxidation of carbon to yield carbon dioxide or the reduction of carbon by hydrogen to yield methane , or it can be a complex process such as the oxidation of sugar in the human body through a ser...
 (effectively, loss of electrons from the nitrogen atom to the oxygen atoms) :

  1. NH3 + CO2 + 1.5 O2 + Nitrosomonas ? NO2- + H2O + H+
  2. NO2- + CO2 + 0.5 O2 + Nitrobacter ? NO3-
  3. NH3 + O2 ? NO2− + 3H+ + 2e−
  4. NO2− + H2O ? NO3− + 2H+ + 2e−


See also

  • Haber process
    Haber process

    The Haber process, also called the Haber?Bosch process, is the nitrogen fixation reaction of nitrogen and hydrogen, over an enriched iron Catalysis, to produce ammonia....


External links

  • at fishdoc.co.uk
  • at University of Aberdeen · King's College
  • at lagoonsonline.com