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Encyclopedia > Nitrogen cycle
Schematic representation of the flow of Nitrogen through the environment. The importance of bacteria in the cycle is immediately recognized as being a key element in the cycle, providing different forms of nitrogen compounds assimilable by higher organisms. See Martinus Beijerinck.
Schematic representation of the flow of Nitrogen through the environment. The importance of bacteria in the cycle is immediately recognized as being a key element in the cycle, providing different forms of nitrogen compounds assimilable by higher organisms. See Martinus Beijerinck.

The nitrogen cycle is the biogeochemical cycle that describes the transformations of nitrogen and nitrogen-containing compounds in nature. This is an image of nitrogen cycle taken from this [1] EPA website. ... This is an image of nitrogen cycle taken from this [1] EPA website. ... Martinus Willem Beijerinck (March 16, 1851 - January 1, 1931) was a Dutch microbiologist and botanist. ... In ecology, a biogeochemical cycle is a circuit where a nutrient moves back and forth between both biotic and abiotic components of ecosystems. ... General Name, symbol, number nitrogen, N, 7 Chemical series nonmetals Group, period, block 15, 2, p Appearance colorless gas Standard atomic weight 14. ...


Earth's atmosphere is about 78% nitrogen, making it the largest pool of nitrogen. Nitrogen is essential for many biological processes; and is crucial for any life here on Earth. It is in all amino acids, is incorporated into proteins, and is present in the bases that make up nucleic acids, such as DNA and RNA. In plants, much of the nitrogen is used in chlorophyll molecules which are essential for photosynthesis and further growth.[1] Air redirects here. ... General Name, symbol, number nitrogen, N, 7 Chemical series nonmetals Group, period, block 15, 2, p Appearance colorless gas Standard atomic weight 14. ... In chemistry, an amino acid is any molecule that contains both amino and carboxylic acid functional groups. ... A representation of the 3D structure of myoglobin, showing coloured alpha helices. ... Highly simplified diagram of a double-stranded nucleic acid. ... The structure of part of a DNA double helix Deoxyribonucleic acid, or DNA, is a nucleic acid molecule that contains the genetic instructions used in the development and functioning of all known living organisms. ... Left: An RNA strand, with its nitrogenous bases. ... u fuck in ua ... Chlorophyll is a green pigment found in most plants, algae, and cyanobacteria. ... The leaf is the primary site of photosynthesis in plants. ...


Processing, or fixation, is necessary to convert gaseous nitrogen into forms usable by living organisms. Some fixation occurs in lightning strikes, but most fixation is done by free-living or symbiotic bacteria. These bacteria have the nitrogenase enzyme that combines gaseous nitrogen with hydrogen to produce ammonia, which is then further converted by the bacteria to make its own organic compounds. Some nitrogen fixing bacteria, such as Rhizobium, live in the root nodules of legumes (such as peas or beans). Here they form a mutualistic relationship with the plant, producing ammonia in exchange for carbohydrates. Nutrient-poor soils can be planted with legumes to enrich them with nitrogen. A few other plants can form such symbioses. Nitrogen fixation is the process by which nitrogen is taken from its relatively inert molecular form (N2) in the atmosphere and converted into nitrogen compounds (such as, notably, ammonia, nitrate and nitrogen dioxide)[1] useful for other chemical processes. ... Not to be confused with lighting. ... Common Clownfish (Amphiprion ocellaris) in their Magnificent Sea Anemone (Heteractis magnifica) home. ... Phyla Actinobacteria Aquificae Chlamydiae Bacteroidetes/Chlorobi Chloroflexi Chrysiogenetes Cyanobacteria Deferribacteres Deinococcus-Thermus Dictyoglomi Fibrobacteres/Acidobacteria Firmicutes Fusobacteria Gemmatimonadetes Lentisphaerae Nitrospirae Planctomycetes Proteobacteria Spirochaetes Thermodesulfobacteria Thermomicrobia Thermotogae Verrucomicrobia Bacteria (singular: bacterium) are unicellular microorganisms. ... Nitrogenase (EC 1. ... Ribbon diagram of the enzyme TIM, surrounded by the space-filling model of the protein. ... This article is about the chemistry of hydrogen. ... For other uses, see Ammonia (disambiguation). ... Benzene is the simplest of the arenes, a family of organic compounds An organic compound is any member of a large class of chemical compounds whose molecules contain carbon. ... Rhizobia (from the Greek words Riza = Root and Bios = Life) are soil bacteria that fix nitrogen (diazotrophy) after becoming established inside root nodules of legumes (Fabaceae). ... Varieties of soybean seeds, a popular legume The term legume has two closely related meanings in botany, a situation encountered with many botanical common names of useful plants whereby an applied name can refer to either the plant itself, or to the edible fruit (or useful part). ... In biology, mutualism is an interaction between two species in which both species derive benefit. ... Carbohydrates (literally hydrates of carbon) are chemical compounds that act as the primary biological means of storing or consuming energy, other forms being fat and protein. ... For other uses, see Symbiosis (disambiguation). ...


Other plants get nitrogen from the soil by absorption at their roots in the form of either nitrate ions or ammonium ions. All nitrogen obtained by animals can be traced back to the eating of plants at some stage of the food chain. Trinitrate redirects here. ... ... A ball-and-stick model of the ammonium cation Ammonium is also an old name for the Siwa Oasis in western Egypt. ... The word Animals when used alone has several possible meanings in the English language. ... Food chains, food webs and/or food networks describe the feeding relationships between species to another within an ecosystem. ...


Due to their very high solubility, nitrates can enter groundwater. Elevated nitrate in groundwater is a concern for drinking water use because nitrate can interfere with blood-oxygen levels in infants and cause methemoglobinemia or blue-baby syndrome.[2] Where groundwater recharges stream flow, nitrate-enriched groundwater can contribute to eutrophication, a process leading to high algal, especially blue-green algal populations and the death of aquatic life due to excessive demand for oxygen. While not directly toxic to fish life like ammonia, nitrate can have indirect effects on fish if it contributes to this eutrophication. Nitrogen has contributed to severe eutrophication problems in some water bodies. As of 2006, the application of nitrogen fertilizer is being increasingly controlled in Britain and the United States. This is occurring along the same lines as control of phosphorus fertilizer, restriction of which is normally considered essential to the recovery of eutrophied waterbodies. Solubility is a chemical property referring to the ability for a given substance, the solute, to dissolve in a solvent. ... Methemoglobinemia, also known as met-Hb, is a disorder characterized by the presence of a higher than normal level of methemoglobin in the blood. ... Eutrophication, strictly speaking, means an increase in chemical nutrients -- typically compounds containing nitrogen or phosphorus -- in an ecosystem. ... The algae (singular is alga) comprise several different groups of living things that produce energy through photosynthesis. ... Spreading manure, an organic fertilizer Fertilizers (also spelled fertilisers) are compounds given to plants to promote growth; they are usually applied either via the soil, for uptake by plant roots, or by foliar feeding, for uptake through leaves. ...


Ammonia is highly toxic to fish life and the water discharge level of ammonia from wastewater treatment plants must often be closely monitored. To prevent loss of fish, nitrification prior to discharge is often desirable. Land application can be an attractive alternative to the mechanical aeration needed for nitrification. Aeration is the process by which air is circulated through, mixed with or dissolved in a liquid (usually water) or substance (such as soil). ...


During anaerobic (low oxygen) conditions, denitrification by bacteria occurs. This results in nitrates being converted to nitrogen gas and returned to the atmosphere. Nitrate can also be reduced to nitrite and subsequently combine with ammonium in the anammox process, which also results in the production of dinitrogen gas. It has been suggested that Anoxic sea water, Oxygen minimum zone, and Hypoxic zone be merged into this article or section. ... This does not cite its references or sources. ... Air redirects here. ... Trinitrate redirects here. ... // Definition The nitrite ion is NO2−. A nitrite compound is one that contains this group, either an ionic compound, or an analogous covalent one. ... A ball-and-stick model of the ammonium cation Ammonium is also an old name for the Siwa Oasis in western Egypt. ... Anammox -acronym for anaerobic ammonium oxidation- is the latest addition to the knowledge on the nitrogen cycle. ...

Contents

Processes of the nitrogen cycle

Nitrogen fixation

Main article: Nitrogen fixation

Nitrogen fixation is the process by which nitrogen is taken from its relatively inert molecular form (N2) in the atmosphere and converted into nitrogen compounds (such as, notably, ammonia, nitrate and nitrogen dioxide)[1] useful for other chemical processes. ...

Conversion of N2

The conversion of nitrogen (N2) from the atmosphere into a form readily available to plants and hence to animals and humans is an important step in the nitrogen cycle, that determines the supply of this essential nutrient. There are four ways to convert N2 (atmospheric nitrogen gas) into more chemically reactive forms:[1]

  1. Biological fixation: some symbiotic bacteria (most often associated with leguminous plants) and some free-living bacteria are able to fix nitrogen and assimilate it as organic nitrogen. An example of mutualistic nitrogen fixing bacteria are the Rhizobium bacteria, which live in legume root nodules. These species are diazotrophs. An example of the free-living bacteria is Azotobacter.
  2. Industrial N-fixation : in the Haber-Bosch process, N2 is converted together with hydrogen gas (H2) into ammonia (NH3) fertilizer and explosives.
  3. Combustion of fossil fuels : automobile engines and thermal power plants, which release NOx.
  4. Other processes : Additionally, the formation of NO from N2 and O2 due to photons and especially lightning, are important for atmospheric chemistry, but not for terrestrial or aquatic nitrogen turnover.

Rhizobia (from the Greek words Riza = Root and Bios = Life) are soil bacteria that fix nitrogen (diazotrophy) after becoming established inside root nodules of legumes (Fabaceae). ... This article is about the fruit of the plants also called legumes. For the plants themselves, see Fabaceae . ... Diazotrophs are microorganisms that fix atmospheric nitrogen gas in to a more usable form such as ammonia. ... Species A. vinladii Azotobacter are usually motile, oval, or spherical bacteria, form thick-walled cysts, and may produce large quantities of capsular slime. ... The Haber Process (also Haber-Bosch process) is the reaction of nitrogen and hydrogen to produce ammonia. ...

Assimilation

Plants can absorb nitrate or ammonium ions from the soil via their root hairs. If nitrate is absorbed, it is first reduced to nitrite ions and then ammonium ions for incorporation into amino acids, nucleic acids, and chlorophyll.[1] In plants which have a mutualistic relationship with rhizobia, some nitrogen is assimilated in the form of ammonium ions directly from the nodules. Animals, fungi, and other heterotrophic organisms absorb nitrogen as amino acids, nucleotides and other small organic molecules. A heterotroph (Greek heteron = (an)other and trophe = nutrition) is an organism that requires organic substrates to get its carbon for growth and development. ... This article is about the class of chemicals. ... A nucleotide is a chemical compound that consists of 3 portions: a heterocyclic base, a sugar, and one or more phosphate groups. ...


Ammonification

When a plant or animal dies, or an animal excretes, the initial form of nitrogen is organic. Bacteria, or in some cases, fungi, converts the organic nitrogen within the remains back into ammonia, a process called ammonification or mineralization.


Nitrification

Main article: Nitrification

The conversion of ammonia to nitrates is performed primarily by soil-living bacteria and other nitrifying bacteria. The primary stage of nitrification, the oxidation of ammonia (NH3) is performed by bacteria such as the Nitrosomonas species, which converts ammonia to nitrites (NO2-). Other bacterial species, such as the Nitrobacter, are responsible for the oxidation of the nitrites into nitrates (NO3-).[1] Nitrogen cycle Nitrification is the biological oxidation of ammonia with oxygen into nitrite followed by the oxidation of these nitrites into nitrates. ... Species Nitrosomonas cryotolerans Nitrosomonas europaea Nitrosomonas is a genus comprising ellipsoidal soil bacteria. ... Nitrobacter is a rod-shaped bacteria, which is an important part of the nitrogen cycle. ...


Denitrification

Main article: Denitrification

Denitrification is the reduction of nitrites back into the largely inert nitrogen gas (N2), completing the nitrogen cycle. This process is performed by bacterial species such as the Pseudomonas and Clostridium in anaerobic conditions.[1] They use the nitrate as an electron acceptor in the place of oxygen during respiration. These facultatively anaerobic bacteria can also live in aerobic conditions. This does not cite its references or sources. ... Type species Pseudomonas aeruginosa Species group P. aeruginosa P. alcaligenes P. anguilliseptica P. argentinensis P. borbori P. citronellolis P. flavescens P. mendocina P. nitroreducens P. oleovorans P. pseudoalcaligenes P. resinovorans P. straminea group P. aurantiaca P. aureofaciens P. chlororaphis P. fragi P. lundensis P. taetrolens group P. antarctica P. azotoformans... Species Clostridium acetobutylicum Clostridium aerotolerans Clostridium botulinum Clostridium colicanis Clostridium difficile Clostridium formicaceticum Clostridium novyi Clostridium perfringens Clostridium sordelli Clostridium tetani Clostridium piliforme Clostridium tyrobutyricum etc. ...


Anaerobic ammonium oxidation

Main article: Anammox

In this biological process, nitrite and ammonium are converted directly into dinitrogen gas. This process makes up a major proportion of dinitrogen conversion in the oceans. Anammox -acronym for anaerobic ammonium oxidation- is the latest addition to the knowledge on the nitrogen cycle. ... // Definition The nitrite ion is NO2−. A nitrite compound is one that contains this group, either an ionic compound, or an analogous covalent one. ... A ball-and-stick model of the ammonium cation Ammonium is also an old name for the Siwa Oasis in western Egypt. ... Dinitrogen, N2, is the most common form of the element nitrogen in normal conditions. ...


Human influences on the nitrogen cycle

As a result of extensive cultivation of legumes (particularly soy, alfalfa, and clover), growing use of the Haber-Bosch process in the creation of chemical fertilizers, and pollution emitted by vehicles and industrial plants, human beings have more than doubled the annual transfer of nitrogen into biologically available forms.[2] In addition, humans have significantly contributed to the transfer of nitrogen trace gases from Earth to the atmosphere, and from the land to aquatic systems. The Haber Process (also Haber-Bosch process) is the reaction of nitrogen and hydrogen to produce ammonia. ... This article is about Earth as a planet. ... Air redirects here. ...


N2O has risen in the atmosphere as a result of agricultural fertilization, biomass burning, cattle and feedlots, and other industrial sources.[3] N2O has deleterious effects in the stratosphere, where it breaks down and acts as a catalyst in the destruction of atmospheric ozone. Ammonia (NH3) in the atmosphere has tripled as the result of human activities. It is a reactant in the atmosphere, where it acts as an aerosol, decreasing air quality and clinging on to water droplets, eventually resulting in acid rain. Fossil fuel combustion has contributed to a 6 or 7 fold increase in NOx flux to the atmosphere. NOx actively alters atmospheric chemistry, and is a precursor of tropospheric (lower atmosphere) ozone production, which contributes to smog, acid rain, and increases nitrogen inputs to ecosystems.[1] Ecosystem processes can increase with nitrogen fertilization, but anthropogenic input can also result in nitrogen saturation, which weakens productivity and can kill plants.[2] Decreases in biodiversity can also result if higher nitrogen availability increases nitrogen-demanding grasses, causing a degradation of nitrogen-poor, species diverse heathlands.[4] Atmosphere diagram showing stratosphere. ... It has been suggested that this article or section be merged into Catalysis. ... For other uses, see Ozone (disambiguation). ... For other uses, see Ammonia (disambiguation). ... Aerosol, is a term derived from the fact that matter floating in air is a suspension (a mixture in which solid or liquid or combined solid-liquid particles are suspended in a fluid). ... Impact from a water drop causes an upward rebound jet surrounded by circular capillary waves. ... The term acid rain is commonly used to mean the deposition of acidic components in rain, snow, fog, dew, or dry particles. ... Fossil fuels or mineral fuels are fossil source fuels, this is, hydrocarbons found within the top layer of the earth’s crust. ... This article is about the chemical reaction combustion. ... Atmospheric chemistry is a branch of atmospheric science in which the chemistry of the Earths atmosphere and that of other planets is studied. ... Atmosphere diagram showing the mesosphere and other layers. ... It has been suggested that Haze be merged into this article or section. ... A coral reef near the Hawaiian islands is an example of a complex marine ecosystem. ... Categories: Biology stubs ... Look up anthropogenic in Wiktionary, the free dictionary. ... Rainforests are among the most biodiverse ecosystems on earth Biodiversity is the variation of taxonomic life forms within a given ecosystem, biome or for the entire Earth. ...


Wastewater

Onsite sewage facilities such as septic tanks and holding tanks release large amounts of nitrogen into the environment by discharging through a drainfield into the ground. Microbial activity consumes the nitrogen and other contaminants in the wastewater. However, in certain areas the soil is unsuitable to handle some or all of the wastewater, and as a result, the wastewater with the contaminants enters the aquifers. These contaminants accumulate and eventually end up in drinking water. One of the contaminants concerned about the most is nitrogen in the form of nitrates. A nitrate concentration of 10 ppm or 10 milligrams per liter is the current EPA limit for drinking water and typical household wastewater can produce a range of 20-85 ppm (milligrams per liter). On Site Sewage Facilities (OSSF) are wastewater systems designed to treat and dispose of effluent on the same property that produces the wastewater. ... An aquifer is an underground layer of water-bearing permeable rock, or permeable mixtures of unconsolidated materials (gravel, sand, silt, or clay) (see also groundwater). ... General Name, symbol, number nitrogen, N, 7 Chemical series nonmetals Group, period, block 15, 2, p Appearance colorless gas Standard atomic weight 14. ... Nitrates are the salts of nitric acid. ...


The health risk associated with drinking >10 ppm nitrogen water is the development of methemoglobinemia and has been found to cause blue baby syndrome. Several states have now started programs to introduce advanced wastewater treatment systems to the typical onsite sewage facilities. The result of these systems is an overall reduction of nitrogen, as well as other contaminants in the wastewater. Methemoglobinemia, also known as met-Hb, is a disorder characterized by the presence of a higher than normal level of methemoglobin in the blood. ... A cyanotic newborn, or blue baby Blue baby syndrome (or simply, blue baby) is a laymans term used to describe newborns with cyanotic conditions, such as: Cyanotic heart defects Tetralogy of Fallot Dextro-Transposition of the great arteries Hypoplastic left heart syndrome Methemoglobinemia On November 29, 1944, the Johns...


Nitrogen is also a form of cloroxide.


References

  1. ^ a b c d e f Smil, V (2000). Cycles of Life. ScientificAmerican Library, New York. , 2000)
  2. ^ a b c Vitousek, PM; Aber, J; Howarth, RW; Likens, GE; Matson, PA; Schindler, DW; Schlesinger, WH; Tilman, GD (1997). "Human Alteration of the Global Nitrogen Cycle: Causes and Consequences". Issues in Ecology 1: 1-17. 
  3. ^ Chapin, S.F. III, Matson, P.A., Mooney H.A. 2002. Principles of Terrestrial Ecosystem Ecology. Springer Publishers:New York
  4. ^ Aerts, R. and F. Berendse. 1988. The effect of increased nutrient availability on vegetation dynamics in wet heathlands. Vegetatio. 76: 63-69

Bibliography

  • The Nitrogen Cycle, and New Tank Syndrome http://www.aquariumdomain.com/guideTheNitrogenCycle.asp, accessed 2006-07-16.
  • Raven, P.H. and G.B. Johnson. 1996. Biology. Wm. C. Brown Publishers.
Biogeochemical cycles
Carbon cycle - Hydrogen cycle - Nitrogen cycle
Oxygen cycle - Phosphorus cycle - Sulfur cycle - Water cycle

  Results from FactBites:
 
nitrogen cycle (311 words)
Nitrogen, in the form of inorganic compounds (such as nitrates) in the soil, is absorbed by plants and turned into organic compounds (such as proteins) in plant tissue.
A proportion of this nitrogen is eaten by herbivores, with some of this in turn being passed on to the carnivores, which feed on the herbivores.
The nitrogen is ultimately returned to the soil as excrement and when organisms die, and is converted back to inorganic forms by decomposers.
  More results at FactBites »

 
 

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