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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. Biogeochemical cycle - Wikipedia

    en.wikipedia.org/wiki/Biogeochemical_cycle

    A biogeochemical cycle, or more generally a cycle of matter, [1] is the movement and transformation of chemical elements and compounds between living organisms, the atmosphere, and the Earth's crust. Major biogeochemical cycles include the carbon cycle, the nitrogen cycle and the water cycle. In each cycle, the chemical element or molecule is ...

  4. File:Nitrogen Cycle 2.svg - Wikipedia

    en.wikipedia.org/wiki/File:Nitrogen_Cycle_2.svg

    This image is a derivative work of the following images: File:Nitrogen Cycle.svg licensed with Cc-by-sa-3.0 . 2009-09-27T05:47:47Z Raeky 800x600 (298078 Bytes) outlines for text

  5. File:Nitrogen Cycle.svg - Wikipedia

    en.wikipedia.org/wiki/File:Nitrogen_Cycle.svg

    You are free: to share – to copy, distribute and transmit the work; to remix – to adapt the work; Under the following conditions: attribution – You must give appropriate credit, provide a link to the license, and indicate if changes were made.

  6. 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 ...

  7. Lichens and nitrogen cycling - Wikipedia

    en.wikipedia.org/wiki/Lichens_and_nitrogen_cycling

    The nitrogen cycle is one of the Earth's biogeochemical cycles. It involves the conversion of nitrogen into different chemical forms. The main processes of the nitrogen cycle are the fixation, ammonification, nitrification, and denitrification. As one of the macronutrients, nitrogen plays an important role in plant growth.

  8. Marine biogeochemical cycles - Wikipedia

    en.wikipedia.org/wiki/Marine_biogeochemical_cycles

    Nitrogen enters the ocean through precipitation, runoff, or as N 2 from the atmosphere. Nitrogen cannot be utilized by phytoplankton as N 2 so it must undergo nitrogen fixation which is performed predominantly by cyanobacteria. [82] Without supplies of fixed nitrogen entering the marine cycle, the fixed nitrogen would be used up in about 2000 ...

  9. 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 ...