Nitrogen Cycle: The circulation of nitrogen in nature, consisting of a cycle of biochemical reactions in which atmospheric nitrogen is compounded, dissolved in rain, and deposited in the soil, where it is assimilated and metabolized by bacteria and plants, eventually returning to the atmosphere by bacterial decomposition of organic matter.Nitrogen Fixation: The process in certain BACTERIA; FUNGI; and CYANOBACTERIA converting free atmospheric NITROGEN to biologically usable forms of nitrogen, such as AMMONIA; NITRATES; and amino compounds.Nitrogen Compounds: Inorganic compounds that contain nitrogen as an integral part of the molecule.Nitrification: A process facilitated by specialized bacteria involving the oxidation of ammonium to nitrite and nitrate.Denitrification: Nitrate reduction process generally mediated by anaerobic bacteria by which nitrogen available to plants is converted to a gaseous form and lost from the soil or water column. It is a part of the nitrogen cycle.Nitrogen: An element with the atomic symbol N, atomic number 7, and atomic weight [14.00643; 14.00728]. Nitrogen exists as a diatomic gas and makes up about 78% of the earth's atmosphere by volume. It is a constituent of proteins and nucleic acids and found in all living cells.Cell Cycle: The complex series of phenomena, occurring between the end of one CELL DIVISION and the end of the next, by which cellular material is duplicated and then divided between two daughter cells. The cell cycle includes INTERPHASE, which includes G0 PHASE; G1 PHASE; S PHASE; and G2 PHASE, and CELL DIVISION PHASE.Planctomycetales: A order of gram-negative bacteria whose members are found in a variety of aquatic habitats as well as animal hosts.Quaternary Ammonium Compounds: Derivatives of ammonium compounds, NH4+ Y-, in which all four of the hydrogens bonded to nitrogen have been replaced with hydrocarbyl groups. These are distinguished from IMINES which are RN=CR2.Nitrogen Isotopes: Stable nitrogen atoms that have the same atomic number as the element nitrogen, but differ in atomic weight. N-15 is a stable nitrogen isotope.Crenarchaeota: A kingdom in the domain ARCHAEA comprised of thermoacidophilic, sulfur-dependent organisms. The two orders are SULFOLOBALES and THERMOPROTEALES.Archaea: One of the three domains of life (the others being BACTERIA and Eukarya), formerly called Archaebacteria under the taxon Bacteria, but now considered separate and distinct. They are characterized by: (1) the presence of characteristic tRNAs and ribosomal RNAs; (2) the absence of peptidoglycan cell walls; (3) the presence of ether-linked lipids built from branched-chain subunits; and (4) their occurrence in unusual habitats. While archaea resemble bacteria in morphology and genomic organization, they resemble eukarya in their method of genomic replication. The domain contains at least four kingdoms: CRENARCHAEOTA; EURYARCHAEOTA; NANOARCHAEOTA; and KORARCHAEOTA.Ammonia: A colorless alkaline gas. It is formed in the body during decomposition of organic materials during a large number of metabolically important reactions. Note that the aqueous form of ammonia is referred to as AMMONIUM HYDROXIDE.Nitrite Reductases: A group of enzymes that oxidize diverse nitrogenous substances to yield nitrite. (Enzyme Nomenclature, 1992) EC 1.Nitrates: Inorganic or organic salts and esters of nitric acid. These compounds contain the NO3- radical.Nitrites: Salts of nitrous acid or compounds containing the group NO2-. The inorganic nitrites of the type MNO2 (where M=metal) are all insoluble, except the alkali nitrites. The organic nitrites may be isomeric, but not identical with the corresponding nitro compounds. (Grant & Hackh's Chemical Dictionary, 5th ed)Seawater: The salinated water of OCEANS AND SEAS that provides habitat for marine organisms.Genes, Archaeal: The functional genetic units of ARCHAEA.Oceans and Seas: A great expanse of continuous bodies of salt water which together cover more than 70 percent of the earth's surface. Seas may be partially or entirely enclosed by land, and are smaller than the five oceans (Atlantic, Pacific, Indian, Arctic, and Antarctic).Bacteria: One of the three domains of life (the others being Eukarya and ARCHAEA), also called Eubacteria. They are unicellular prokaryotic microorganisms which generally possess rigid cell walls, multiply by cell division, and exhibit three principal forms: round or coccal, rodlike or bacillary, and spiral or spirochetal. Bacteria can be classified by their response to OXYGEN: aerobic, anaerobic, or facultatively anaerobic; by the mode by which they obtain their energy: chemotrophy (via chemical reaction) or PHOTOTROPHY (via light reaction); for chemotrophs by their source of chemical energy: CHEMOLITHOTROPHY (from inorganic compounds) or chemoorganotrophy (from organic compounds); and by their source for CARBON; NITROGEN; etc.; HETEROTROPHY (from organic sources) or AUTOTROPHY (from CARBON DIOXIDE). They can also be classified by whether or not they stain (based on the structure of their CELL WALLS) with CRYSTAL VIOLET dye: gram-negative or gram-positive.Nitrous Oxide: Nitrogen oxide (N2O). A colorless, odorless gas that is used as an anesthetic and analgesic. High concentrations cause a narcotic effect and may replace oxygen, causing death by asphyxia. It is also used as a food aerosol in the preparation of whipping cream.Ecosystem: A functional system which includes the organisms of a natural community together with their environment. (McGraw Hill Dictionary of Scientific and Technical Terms, 4th ed)DNA, Archaeal: Deoxyribonucleic acid that makes up the genetic material of archaea.Soil Microbiology: The presence of bacteria, viruses, and fungi in the soil. This term is not restricted to pathogenic organisms.Geologic Sediments: A mass of organic or inorganic solid fragmented material, or the solid fragment itself, that comes from the weathering of rock and is carried by, suspended in, or dropped by air, water, or ice. It refers also to a mass that is accumulated by any other natural agent and that forms in layers on the earth's surface, such as sand, gravel, silt, mud, fill, or loess. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed, p1689)Soil: The unconsolidated mineral or organic matter on the surface of the earth that serves as a natural medium for the growth of land plants.Climate Change: Any significant change in measures of climate (such as temperature, precipitation, or wind) lasting for an extended period (decades or longer). It may result from natural factors such as changes in the sun's intensity, natural processes within the climate system such as changes in ocean circulation, or human activities.Oxidation-Reduction: A chemical reaction in which an electron is transferred from one molecule to another. The electron-donating molecule is the reducing agent or reductant; the electron-accepting molecule is the oxidizing agent or oxidant. Reducing and oxidizing agents function as conjugate reductant-oxidant pairs or redox pairs (Lehninger, Principles of Biochemistry, 1982, p471).Phylogeny: The relationships of groups of organisms as reflected by their genetic makeup.Agriculture: The science, art or practice of cultivating soil, producing crops, and raising livestock.Blood Urea Nitrogen: The urea concentration of the blood stated in terms of nitrogen content. Serum (plasma) urea nitrogen is approximately 12% higher than blood urea nitrogen concentration because of the greater protein content of red blood cells. Increases in blood or serum urea nitrogen are referred to as azotemia and may have prerenal, renal, or postrenal causes. (From Saunders Dictionary & Encyclopedia of Laboratory Medicine and Technology, 1984)Nitrogen Dioxide: Nitrogen oxide (NO2). A highly poisonous gas. Exposure produces inflammation of lungs that may only cause slight pain or pass unnoticed, but resulting edema several days later may cause death. (From Merck, 11th ed) It is a major atmospheric pollutant that is able to absorb UV light that does not reach the earth's surface.Trees: Woody, usually tall, perennial higher plants (Angiosperms, Gymnosperms, and some Pterophyta) having usually a main stem and numerous branches.Menstrual Cycle: The period from onset of one menstrual bleeding (MENSTRUATION) to the next in an ovulating woman or female primate. The menstrual cycle is regulated by endocrine interactions of the HYPOTHALAMUS; the PITUITARY GLAND; the ovaries; and the genital tract. The menstrual cycle is divided by OVULATION into two phases. Based on the endocrine status of the OVARY, there is a FOLLICULAR PHASE and a LUTEAL PHASE. Based on the response in the ENDOMETRIUM, the menstrual cycle is divided into a proliferative and a secretory phase.Biodiversity: The variety of all native living organisms and their various forms and interrelationships.Reactive Nitrogen Species: Nitrogenous products of NITRIC OXIDE synthases, ranging from NITRIC OXIDE to NITRATES. These reactive nitrogen intermediates also include the inorganic PEROXYNITROUS ACID and the organic S-NITROSOTHIOLS.Oxidoreductases: The class of all enzymes catalyzing oxidoreduction reactions. The substrate that is oxidized is regarded as a hydrogen donor. The systematic name is based on donor:acceptor oxidoreductase. The recommended name will be dehydrogenase, wherever this is possible; as an alternative, reductase can be used. Oxidase is only used in cases where O2 is the acceptor. (Enzyme Nomenclature, 1992, p9)Molecular Sequence Data: Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.Cell Cycle Proteins: Proteins that control the CELL DIVISION CYCLE. This family of proteins includes a wide variety of classes, including CYCLIN-DEPENDENT KINASES, mitogen-activated kinases, CYCLINS, and PHOSPHOPROTEIN PHOSPHATASES as well as their putative substrates such as chromatin-associated proteins, CYTOSKELETAL PROTEINS, and TRANSCRIPTION FACTORS.RNA, Ribosomal, 16S: Constituent of 30S subunit prokaryotic ribosomes containing 1600 nucleotides and 21 proteins. 16S rRNA is involved in initiation of polypeptide synthesis.Nitrogen Oxides: Inorganic oxides that contain nitrogen.Genome, Bacterial: The genetic complement of a BACTERIA as represented in its DNA.PII Nitrogen Regulatory Proteins: A family of signal transducing adaptor proteins that control the METABOLISM of NITROGEN. They are primarily found in prokaryotes.Sequence Analysis, DNA: A multistage process that includes cloning, physical mapping, subcloning, determination of the DNA SEQUENCE, and information analysis.Carbon: A nonmetallic element with atomic symbol C, atomic number 6, and atomic weight [12.0096; 12.0116]. It may occur as several different allotropes including DIAMOND; CHARCOAL; and GRAPHITE; and as SOOT from incompletely burned fuel.Estrous Cycle: The period of cyclic physiological and behavior changes in non-primate female mammals that exhibit ESTRUS. The estrous cycle generally consists of 4 or 5 distinct periods corresponding to the endocrine status (PROESTRUS; ESTRUS; METESTRUS; DIESTRUS; and ANESTRUS).Fertilizers: Substances or mixtures that are added to the soil to supply nutrients or to make available nutrients already present in the soil, in order to increase plant growth and productivity.Citric Acid Cycle: A series of oxidative reactions in the breakdown of acetyl units derived from GLUCOSE; FATTY ACIDS; or AMINO ACIDS by means of tricarboxylic acid intermediates. The end products are CARBON DIOXIDE, water, and energy in the form of phosphate bonds.Glutamate-Ammonia Ligase: An enzyme that catalyzes the conversion of ATP, L-glutamate, and NH3 to ADP, orthophosphate, and L-glutamine. It also acts more slowly on 4-methylene-L-glutamate. (From Enzyme Nomenclature, 1992) EC

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Like carbon, nitrogen has its own biogeochemical cycle, circulating through the atmosphere, lithosphere, and hydrosphere (). ... Nitrogen is one of the elements most likely to be limiting to plant growth. ... Unlike carbon, which is stored primarily in sedimentary rock, most nitrogen occurs in the... ... As is true in the nitrogen cycle, the activities of microorganisms are crucial in the global cycling of this nutrient. ...

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Investigating nitrogen removal pathways in a major land-ocean interface ... Moreover, we will apply high-throughput molecular techniques to identify microbes that are important to nitrogen cycling in the ... This nitrogen-bearing groundwater enters coastal waters from a seepage face near the intertidal zone or flows directly into the ... The study will be particularly focused on loss of fixed nitrogen due to production of N2 gas, and will involve a new combined ...

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The nitrogen cycle. The nitrogen cycle is essential for the life on planet Earth and certainly also for our life as humans. ... The nitrogen cycle. Key words:. Nitrogen fixation, Nitrification, Denitrification, Assimilation, Fertilisation, Nitrogen oxide ... 1. The nitrogen cycle: A = Assimilation by plants, F = Fixation of nitrogen by bacteria either in symbiosis with plants or by ... 2. The biological nitrogen cycle in the soil consists of a) nitrogen fixation by bacteria which can live in symbiosis with ...

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Bacterial role in nitrogen cycle - Bacterial Cell Wall Synthesis: New Insights from .... Bowtrol Probiotic improve gastrointestinal function & intestinal good bacterial microbial balance.

Human impact on the nitrogen cycleDiazotroph: Diazotrophs are bacteria and archaea that fix atmospheric nitrogen gas into a more usable form such as ammonia.Nitrogen trichlorideWarner OlandAerobic denitrification: Aerobic denitrification or co-respiration the simultaneous use of both oxygen (O2) and nitrate (NO3−) as oxidizing agents, performed by various genera of microorganisms. This process differs from anaerobic denitrification not only in its insensitivity to the presence of oxygen, but also in that it has a higher potential to create the harmful byproduct nitrous oxide.Nitrogen deficiencyStart point (yeast): The Start checkpoint is a major cell cycle checkpoint in yeast. The Start checkpoint ensures irreversible cell-cycle entry even if conditions later become unfavorable.Scalindua wagneri: Candidatus Scalindua wagneri is a Gram-negative coccoid-shaped bacterium that was first isolated from a wastewater treatment plant. This bacterium is an obligate anaerobic chemolithotroph that undergoes anaerobic ammonium oxidation (anammox).Tetramethylammonium chlorideIsotopic signature: An isotopic signature (also isotopic fingerprint) is a ratio of non-radiogenic 'stable isotopes', stable radiogenic isotopes, or unstable radioactive isotopes of particular elements in an investigated material. The ratios of isotopes in a sample material are measured by isotope ratio mass spectrometry.Domain (biology): In biological taxonomy, a domain (also superregnum, superkingdom, empire, or regio) is the highest taxonomic rank of organisms in the three-domain system of taxonomy designed by Carl Woese, an American microbiologist and biophysicist. According to the Woese system, introduced in 1990, the tree of life consists of three domains: Archaea (a term which Woese created), Bacteria, and Eukaryota.Ammonia transporterPeroxynitrous acidHyponitriteDeep chlorophyll maximum: A deep chlorophyll maximum (DCM) is a subsurface maximum in the concentration of chlorophyll in the ocean or a lake. A DCM is not always present--sometimes there is more chlorophyll at the surface than at any greater depth--but it is a common feature of most aquatic ecosystems.Anoxic event: Oceanic anoxic events or anoxic events (anoxia conditions) refer to intervals in the Earth's past where portions of oceans become depleted in oxygen (O2) at depths over a large geographic area. During some of these events, euxinia develops - euxinia refers to anoxic waters that contain hydrogen sulfide.Exogenous bacteria: Exogenous bacteria are microorganisms introduced to closed biological systems from the external world. They exist in aquatic and terrestrial environments, as well as the atmosphere.Nitrous oxide and oxygen: A mix of nitrous oxide 50% and oxygen 50% is a medical analgesic gas, commonly known as Entonox (a registered trademark of BOC) or Nitronox, or colloquially as "gas and air", and is frequently used in pre-hospital care, childbirth and emergency medicine situations by medical professionals such as doctors, nurses, midwives and paramedics.EcosystemGemmatimonadetes: The Gemmatimonadetes are a family of bacteria, given their own phylum (Gemmatimonadetes). This bacterium makes up about 2% of soil bacterial communities and has been identified as one of the top nine phyla found in soils; yet, there are currently only six cultured isolates.Nankai Trough gas hydrate site: Nankai Methane Hydrate Site (or Japanese Methane Hydrate R&D Program at Nankai, Nankai Trough Methane Hydrate Site) is located in the Nankai Trough, Japan.Index of soil-related articles: This is an index of articles relating to soil.Climate change in the United Kingdom: Climate change in the United Kingdom has been a subject of protests and controversies, and various policies have been developed to mitigate its effects. It is estimated to demand at least 80-85% emission reductions in the EU during 2008-2050 with reductions as soon as technically possible.Table of standard reduction potentials for half-reactions important in biochemistry: The values below are standard reduction potentials for half-reactions measured at 25°C, 1 atmosphere and a pH of 7 in aqueous solution.Branching order of bacterial phyla (Gupta, 2001): There are several models of the Branching order of bacterial phyla, one of these was proposed in 2001 by Gupta based on conserved indels or protein, termed "protein signatures", an alternative approach to molecular phylogeny. Some problematic exceptions and conflicts are present to these conserved indels, however, they are in agreement with several groupings of classes and phyla.Chilalo Agricultural Development Union: Chilalo Agricultural Development Union (CADU) is the first comprehensive package project established in Arsi Zone, Oromia Region, Ethiopia to modernize traditional subsistence agriculture. The major components of the package programmes include fertilizers, ameliorated seeds, farm credits, marketing facilities, better tools and implements, and improved storage facilities.Renal functionPeat swamp forest: Peat swamp forests are tropical moist forests where waterlogged soil prevents dead leaves and wood from fully decomposing. Over time, this creates a thick layer of acidic peat.Alliance for Zero Extinction: Formed in 2000 and launched globally in 2005, the Alliance for Zero Extinction (AZE) comprises 100 non-governmental biodiversity conservation organizations working to prevent species extinctions by identifying and safeguarding sites where species evaluated to be Endangered or Critically Endangered under International Union for Conservation of Nature (IUCN) criteria only exist at one location on earth."Zero Extinction - Home.NitrotyrosineGlucose-methanol-choline oxidoreductase family: In molecular biology, the glucose-methanol-choline oxidoreductase family (GMC oxidoreductase) is a family of enzymes with oxidoreductase activity.Coles PhillipsNitrogen oxide sensor: A nitrogen oxide sensor or NOx sensor is typically a high-temperature device built to detect nitrogen oxides in combustion environments such as an automobile or truck tailpipe or a smokestack.Global microbial identifier: The genomic epidemiological database for global identification of microorganisms or global microbial identifier (GMI) is a platform for storing whole genome sequencing (WGS) data of microorganisms, for the identification of relevant genes and for the comparison of genomes to detect and track-and-trace infectious disease outbreaks and emerging pathogens. The database holds two types of information: 1) genomic information of microorganisms, linked to, 2) metadata of those microorganism such as epidemiological details.Pii nitrogen regulatory proteinsDNA sequencer: A DNA sequencer is a scientific instrument used to automate the DNA sequencing process. Given a sample of DNA, a DNA sequencer is used to determine the order of the four bases: G (guanine), C (cytosine), A (adenine) and T (thymine).Carbon–carbon bond: A carbon–carbon bond is a covalent bond between two carbon atoms. The most common form is the single bond: a bond composed of two electrons, one from each of the two atoms.Estrous cycle: The estrous cycle (also oestrous cycle; derived from Latin oestrus and originally from Greek οἶστρος meaning sexual desire) comprises the recurring physiologic changes that are induced by reproductive hormones in most mammalian therian females. Estrous cycles start after sexual maturity in females and are interrupted by anestrous phases or pregnancies.Organic fertilizer: Organic fertilizers are fertilizers derived from animal matter, human excreta or vegetable matter. (e.Reverse Krebs cycle: The reverse Krebs cycle (also known as the reverse tricarboxylic acid cycle, the reverse TCA cycle, or the reverse citric acid cycle)Glutamine synthetase

(1/78) Microbial communities and functional genes associated with soil arsenic contamination and the rhizosphere of the arsenic-hyperaccumulating plant Pteris vittata L.


(2/78) Plant-ants feed their host plant, but above all a fungal symbiont to recycle nitrogen.


(3/78) A cryptic sulfur cycle in oxygen-minimum-zone waters off the Chilean coast.


(4/78) Indications of recovery from hypoxia in the inner Stockholm archipelago.

Improved benthic conditions compared to the 1990s were found during benthic investigations, including sediment and benthic macrofauna in the inner Stockholm archipelago during 2008. In the 1990s, these areas were dominated by black and laminated surface sediments and very sparse fauna. A clear relationship was found when comparing sediment status with the benthic macrofauna. Reduced surface sediment and impoverished macroinvertebrate community was only found at one sampling station representing an enclosed part of the inner archipelago, whereas the other seven stations, with depths ranging from 20 to 50 m, had oxidized surface sediments and considerable biomasses of benthic macrofauna (6-65 g m(-2)) dominated by the invading polychaete Marenzelleria neglecta. An extrapolation of the results shows that, within the investigated area, the coverage of reduced surface sediments had decreased from approximately 17% in the late 1990s to 4% in 2008.  (+info)

(5/78) Global declines in oceanic nitrification rates as a consequence of ocean acidification.


(6/78) Four PCR primers necessary for the detection of periplasmic nitrate reductase genes in all groups of Proteobacteria and in environmental DNA.


(7/78) Stability in ecosystem functioning across a climatic threshold and contrasting forest regimes.


(8/78) Amino acid export in plants: a missing link in nitrogen cycling.


atmospheric nitrogen

  • Although the fixation of atmospheric nitrogen is an essential part of the nitrogen cycle, ammonification and nitrification are the predominant methods by which organic nitrogen is prevented from returning to the atmosphere and is kept cycling through the biosphere. (
  • Atmospheric organic nitrogen (ON) appears to be a ubiquitous but poorly understood component of the atmospheric nitrogen deposition flux. (
  • Here, we focus on the ON components that dominate deposition and do not consider reactive atmospheric gases containing ON such as peroxyacyl nitrates that are important in atmospheric nitrogen transport, but are probably not particularly important in deposition. (
  • Nitrogen-fixing bacteria , microorganisms capable of transforming atmospheric nitrogen into fixed nitrogen (inorganic compounds usable by plants). (


  • Other microorganisms perform important tasks that propel the nitrogen cycle along. (
  • As is true in the nitrogen cycle, the activities of microorganisms are crucial in the global cycling of this nutrient. (
  • Basically the nitrogen cycle consists of chemical reactions in the air (oxidation is dominant) and of chemical reactions in the biosphere, either plants or microorganisms in the soil (oxidation or reduction). (


  • This reductive process, called nitrogen fixation , is a chemical reaction in which electrons are picked up from another molecule. (
  • 1. The nitrogen cycle: A = Assimilation by plants, F = Fixation of nitrogen by bacteria either in symbiosis with plants or by free living bacteria in the soil, N = Nitrification, D = Denitrification, M = Mineralisation - Please click the image in order to enlarge it. (
  • The conversion between both forms takes place during nitrogen fixation or denitrification. (
  • Nitrogen fixation is the process of making available nitrogen compounds in the air (mainly molecular nitrogen N 2 ) to plants. (
  • Nitrogen fixation is possible for many bacteria and cyanobacteria. (
  • Products of nitrogen fixation are ammonia, nitrites or nitrates. (
  • Nitrification is the second step of nitrogen fixation. (
  • If we see ammonia as primary product of nitrogen fixation we can call the conversion of ammonia to nitrites and nitrates (carried out by nitrifying bacteria) nitrification. (
  • 2. The biological nitrogen cycle in the soil consists of a) nitrogen fixation by bacteria which can live in symbiosis with plants (like here with the roots of the soy bean) and b) denitrification by other bacteria which set free molecular nitrogen or N 2 O in nitrate respiration. (
  • More than 90 percent of all nitrogen fixation is effected by these organisms, which thus play an important role in the nitrogen cycle . (

inorganic nitrogen

  • Assimilation is the conversion of inorganic nitrogen (such as nitrate) into an organic form of nitrogen like, for example, an amino acid. (
  • ON in rain and aerosol samples represents the total nitrogen (TN) content minus the amounts of nitrate and ammonium (the dominant inorganic nitrogen components), i.e. (

denitrifying bacteria

  • Some nitrogen does return to the atmosphere, however, as denitrifying bacteria break down nitrates to obtain oxygen, thereby releasing gaseous N 2 . (


  • As these organisms die, certain microbes such as detritivores are able to participate in the decomposition of organic nitrogen into ammonia ( ammonification ), providing a constant supply of ammonia to be used in the process of nitrification. (
  • Nitrogen is also lost from plants and soil in terrestrial environments via other routes, including erosion, runoff , volatilization of ammonia into the atmosphere, and leaching from soils into lakes and streams. (
  • In nature, nitrogen can be available in forms accessible to plants (like nitrates or ammonia compounds) or inaccessible to plants (like molecular nitrogen or nitrous oxide). (
  • Some choose to use a slightly higher level so they can house more stock when complete, but high ammonia can cause a cycle to stall and play catch up sometimes, so keepers must be aware. (
  • At this point the filter contains bacteria that break down ammonia into nitrite, so the cycle has commenced. (
  • Within the nodules the bacteria convert free nitrogen to ammonia , which the host plant utilizes for its development. (


  • There are a few gaseous ON compounds, including peroxyacyl nitrates, HCN, HNCO and CH 3 CN and low molecular weight alkyl nitrates that are important components of the global nitrogen transport system. (


  • Nitrogen compounds play an important role in the metabolism of living organisms. (
  • Many organic molecules in the bodies of plants, animals and humans include nitrogen compounds (for example amino-acids, proteins and DNA). (
  • But nitrogen compounds are also present in chemical processes in the atmosphere and have an impact on the climate system. (
  • Plants depend on nitrogen compounds in order to grow. (
  • 3. Assimilation and mineralisation determine the uptake of nitrogen compounds from soil and the incorporation into the biomolecules of plants, or the conversion to anorganic nitrogen after the death of the plant respectively. (
  • Accessible nitrogen compounds can be stored in the soil in an inorganic form (nitrate) or be included into a living organism as organic nitrogen. (
  • However, these compounds are not efficiently deposited, although they can become efficiently deposited after chemical reaction [ 6 ], and hence probably not of major importance in terms of overall nitrogen deposition and are not specifically considered here. (


  • Anammox provides a mechanism for "short circuiting" the N cycle by eliminating the need for nitrification prior to N2 gas production. (

biogeochemical cycle

  • A portion of the biogeochemical cycle of all elements involves time spent cycling through the hydrosphere. (


  • Once nitrogen has been assimilated by plants, it can be converted to organic forms, such as amino acids and proteins. (
  • Animals can use only organic nitrogen, which they obtain by consuming plants or other animals. (
  • Mineralisation (ammoniafication) is a process during which decomposers like earthworms, termites, slugs, snails, bacteria or fungi convert the organic nitrogen of dead plants into inorganic forms. (
  • The role of organic matter in the atmosphere attracts interest and much current research, both as a vector of global biogeochemical cycles and also because of the potential role of aerosol organic matter within the Earth's radiation budget and in cloud processes [ 1 - 4 ]. (
  • The focus in this contribution is on a sub-component of the atmospheric organic matter, organic nitrogen (ON) and its role within the global nitrogen cycle, a cycle which is known to be considerably disturbed by human activity [ 5 ]. (
  • The TN is measured after strong oxidation of samples, which is assumed to convert all organic-bound nitrogen species present in the sample to a readily measured inorganic form [ 8 ]. (
  • In terrestrial ecosystems , much of the available phosphorus moves in a closed cycle between living organisms and the organic debris in the soil. (


  • In this symbiotic association, the bacteria become encased in nodules that grow on the roots of plants, through which nitrogen that has been fixed by the resident bacteria is obtained. (
  • The symbiotic nitrogen-fixing bacteria invade the root hairs of host plants, where they multiply and stimulate formation of root nodules, enlargements of plant cells and bacteria in intimate association. (


  • Consequently, they cycle through the biosphere differently from carbon, nitrogen, and sulfur, all of which sometimes occur as volatile gases. (
  • Water itself cycles within the biosphere. (


  • Unlike carbon, which is stored primarily in sedimentary rock , most nitrogen occurs in the atmosphere as an inorganic compound (N 2 ). (
  • A small amount of nitrogen is fixed by lightning, but most of the nitrogen harvested from the atmosphere is removed by nitrogen-fixing bacteria and cyanobacteria (formerly called blue-green algae ). (
  • Once in the ocean, some of the sulfur cycles through marine communities as it moves through food chains, some reenters the atmosphere, and some is lost to the ocean depths as it combines with iron to form ferrous sulfide (FeS), which is responsible for the black colour of marine sediments. (
  • A minute percentage of the water, however, continually cycles through the atmosphere, oceans, and terrestrial environments mainly by the processes of evaporation and precipitation . (
  • Although 78 percent by volume of the atmosphere is nitrogen gas, this abundant reservoir exists in a form unusable by most organisms. (


  • In coastal watersheds with soils of high hydraulic conductivity and permeable marine sediments, a major source of coastal pollution is groundwater-transported nitrogen (N), which is added to the aquifer primarily from wastewater, fertilizers, and atmospheric deposition. (
  • Finally, we suggest that the flux of ON is about 25 per cent of the total nitrogen deposition flux. (


  • This can be combustion in the hot part of vegetation fires or oxidation of the (under normal conditions inert) molecular nitrogen in lightning or volcano eruptions. (


  • It has been discovered that sulfur availability influences the rate of nitrogen accumulation in plants and nitrogen availability influences phosphorus uptake. (


  • Nitrogen, a component of proteins and nucleic acids, is essential to life on Earth. (


  • This proposal is concerned with a major shift in our understanding of microbial nitrogen transformations that have been shown or proposed to occur in marine environments. (


  • Five pairs of degenerate primers were designed to target archaeal genes encoding key enzymes of nitrogen cycling: nitrite reductases NirA and NirB, nitrous oxide reductase (NosZ), nitrogenase reductase (NifH), and nitrate reductases NapA/NarG. (
  • Denitrification is the process of reduction of nitrate to nitrogen. (

Phosphorus Cycle

  • The addition of phosphorus to soils poor in this nutrient and the use of phosphorus-rich detergents have had a great impact on the phosphorus cycle in many ecosystems. (

living organisms

  • Unlike the cycles of the other major nutrients, however, the hydrologic, or water, cycle would continue in some form even in the absence of living organisms. (


  • The implications of these "new" pathways for the marine N cycle are largely unexplored. (
  • The study will be particularly focused on loss of fixed nitrogen due to production of N2 gas, and will involve a new combined application of isotope pairing and membrane inlet mass spectrometry techniques to quantify and identify pathways of N2 production. (
  • The most important pathways of natural production of nitrogen oxides are oxidation processes under very hot conditions. (


  • The Nitrogen Cycle is a fixed biological process that can not be sped up, only the addition of pre-seeded filter media from a mature tank will help. (


  • Maintaining a healthy aquarium starts with understanding the nitrogen cycle and its effect on the inhabitants. (
  • It is important to stock your new aquarium slowly and to allow the cycle to be completed prior to adding any new inhabitants. (
  • Is it essential to cycle the tank before you put guppies in, or do guppies not need to have cycled aquarium water? (

amino acids

  • 4. Amino acids (here a selection) are nitrogen containing biomolecules. (


  • Most phosphorus cycling occurs between the surface and depths of the ocean. (


  • Moreover, we will apply high-throughput molecular techniques to identify microbes that are important to nitrogen cycling in the permeable sediment system. (


  • Phosphate (PO 4 3− ) is the only important inorganic form involved in this cycle. (


  • For a detailed discussion of the hydrologic cycle see hydrosphere: The hydrologic cycle . (


  • The nitrogen cycle is essential for the life on planet Earth and certainly also for our life as humans. (
  • Is it essential to cycle the tank before you put a betta fish in? (


  • circulation of nitrogen in various forms through nature. (


  • All of the previous situations can cause an imbalance in the nitrogen cycle, and make it necessary for us to monitor the level of toxins in the system whenever they occur. (


  • Nitrogen is one of the elements most likely to be limiting to plant growth. (
  • Although the overall pattern of cycling of all the major elements is now known, there is still much to learn about the relative importance of the different stages of each cycle. (


  • The chlorine in the water will kill the bacteria you are trying to grow for the cycle. (


  • and (4) to illuminate the unseen biodiversity in natural systems, such as caves and aquifers, and how this biodiversity impact biogeochemical cycles. (


  • There have been recent reviews of aspects of atmospheric ON [ 8 , 9 ], and so here we do not attempt a comprehensive review but build on those other reviews and focus on new insights into sources of ON and the importance of this material in the global nitrogen cycle. (


  • To get the pond back in balance so the normal cycle can take place, you may also need to boost the level of nitrifying bacteria on a regular basis. (


  • If pH falls to 6 or below, this can cause a cycle to stall but there are easy ways to rectify this. (