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  2. Nitrogen cycle - Wikipedia

    en.wikipedia.org/wiki/Nitrogen_cycle

    The nitrogen cycle is of particular interest to ecologists because nitrogen availability can affect the rate of key ecosystem processes, including primary production and decomposition. Human activities such as fossil fuel combustion, use of artificial nitrogen fertilizers, and release of nitrogen in wastewater have dramatically altered the ...

  3. Nitrification - Wikipedia

    en.wikipedia.org/wiki/Nitrification

    Nitrogen cycle. Nitrification is the biological oxidation of ammonia to nitrate via the intermediary nitrite. Nitrification is an important step in the nitrogen cycle in soil. The process of complete nitrification may occur through separate organisms [1] or entirely within one organism, as in comammox bacteria. The transformation of ammonia to ...

  4. Denitrifying bacteria - Wikipedia

    en.wikipedia.org/wiki/Denitrifying_bacteria

    The most common denitrification process is outlined below, with the nitrogen oxides being converted back to gaseous nitrogen: 2 NO 3 − + 10 e − + 12 H + → N 2 + 6 H 2 O. The result is one molecule of nitrogen and six molecules of water. Denitrifying bacteria are a part of the N cycle, and consists of sending the N back into the atmosphere.

  5. Category:Nitrogen cycle - Wikipedia

    en.wikipedia.org/wiki/Category:Nitrogen_cycle

    Nitrogen is a critical chemical element in both proteins and nucleic acids, and thus every living organism must metabolize nitrogen to survive. Only bacteria and Archaea are able to convert nitrogen gas (N 2 ) to and from soluble ionic compounds that other organisms can metabolize.

  6. Chemical cycling - Wikipedia

    en.wikipedia.org/wiki/Chemical_cycling

    An example chemical cycle, a schematic representation of a Nitrogen cycle on Earth. This process results in the continual recycling of nitrogen gas involving the ocean. Chemical cycling describes systems of repeated circulation of chemicals between other compounds, states and materials, and back to their original state, that occurs in space ...

  7. Denitrification - Wikipedia

    en.wikipedia.org/wiki/Denitrification

    The lighter isotope of nitrogen, 14 N, is preferred during denitrification, leaving the heavier nitrogen isotope, 15 N, in the residual matter. This selectivity leads to the enrichment of 14 N in the biomass compared to 15 N. [ 27 ] Moreover, the relative abundance of 14 N can be analyzed to distinguish denitrification apart from other ...

  8. Marine biogeochemical cycles - Wikipedia

    en.wikipedia.org/wiki/Marine_biogeochemical_cycles

    The nitrogen cycle is of particular interest to ecologists because nitrogen availability can affect the rate of key ecosystem processes, including primary production and decomposition. Human activities such as fossil fuel combustion, use of artificial nitrogen fertilizers, and release of nitrogen in wastewater have dramatically altered the ...

  9. Human impact on the nitrogen cycle - Wikipedia

    en.wikipedia.org/wiki/Human_impact_on_the...

    Approximately 78% of Earth's atmosphere is N gas (N 2), which is an inert compound and biologically unavailable to most organisms.In order to be utilized in most biological processes, N 2 must be converted to reactive nitrogen (Nr), which includes inorganic reduced forms (NH 3 and NH 4 +), inorganic oxidized forms (NO, NO 2, HNO 3, N 2 O, and NO 3 −), and organic compounds (urea, amines, and ...