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  2. Nitrogen cycle - Wikipedia

    en.wikipedia.org/wiki/Nitrogen_cycle

    The nitrogen cycle is the biogeochemical cycle by which nitrogen is converted into multiple chemical forms as it circulates among atmospheric, terrestrial, and marine ecosystems. The conversion of nitrogen can be carried out through both biological and physical processes. Important processes in the nitrogen cycle include fixation ...

  3. Nutrient cycle - Wikipedia

    en.wikipedia.org/wiki/Nutrient_cycle

    A nutrient cycle (or ecological recycling) is the movement and exchange of inorganic and organic matter back into the production of matter. Energy flow is a unidirectional and noncyclic pathway, whereas the movement of mineral nutrients is cyclic. Mineral cycles include the carbon cycle, sulfur cycle, nitrogen cycle, water cycle, phosphorus ...

  4. Human impact on the nitrogen cycle - Wikipedia

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

    Human impact on the nitrogen cycle is diverse. Agricultural and industrial nitrogen (N) inputs to the environment currently exceed inputs from natural N fixation. [1] As a consequence of anthropogenic inputs, the global nitrogen cycle (Fig. 1) has been significantly altered over the past century. Global atmospheric nitrous oxide (N 2 O) mole ...

  5. Nitrification - Wikipedia

    en.wikipedia.org/wiki/Nitrification

    Nitrification. 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.

  6. Nitrogen assimilation - Wikipedia

    en.wikipedia.org/wiki/Nitrogen_assimilation

    Nitrogen assimilation. Nitrogen assimilation is the formation of organic nitrogen compounds like amino acids from inorganic nitrogen compounds present in the environment. Organisms like plants, fungi and certain bacteria that can fix nitrogen gas (N 2) depend on the ability to assimilate nitrate or ammonia for their needs.

  7. 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 ...

  8. Natural environment - Wikipedia

    en.wikipedia.org/wiki/Natural_environment

    The nitrogen cycle is the transformation of nitrogen and nitrogen-containing compounds in nature. It is a cycle which includes gaseous components. The water cycle, is the continuous movement of water on, above, and below the surface of the Earth. Water can change states among liquid, vapour, and ice at various places in the water cycle.

  9. Eutrophication - Wikipedia

    en.wikipedia.org/wiki/Eutrophication

    e. Eutrophication is a general term describing a process in which nutrients accumulate in a body of water, resulting in an increased growth of microorganisms that may deplete the water of oxygen. [1][2] Eutrophication may occur naturally or as a result of human actions. Manmade, or cultural, eutrophication occurs when sewage, industrial ...