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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. File:Aquarium Nitrogen Cycle.svg - Wikipedia

    en.wikipedia.org/wiki/File:Aquarium_Nitrogen...

    {{Information| |Description=Diagram of the nitrogen cycle in an aquarium. |Source=Own work, drawn in Sodipodi and Inkscape by Ilmari Karonen. |Date=2005-10-2 File usage The following 4 pages use this file:

  4. 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 ...

  5. 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

  6. 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 ...

  7. 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 ...

  8. Dilution refrigerator - Wikipedia

    en.wikipedia.org/wiki/Dilution_refrigerator

    Schematic diagram of a cryogen-free, or dry, dilution refrigerator precooled by a two-stage pulse tube refrigerator, indicated by the dotted rectangle. A 3 He/ 4 He dilution refrigerator is a cryogenic device that provides continuous cooling to temperatures as low as 2 mK, with no moving parts in the low-temperature region.

  9. Pressure swing adsorption - Wikipedia

    en.wikipedia.org/wiki/Pressure_swing_adsorption

    When the bed reaches the limit of its capacity to adsorb nitrogen, it can be regenerated by decreasing the pressure, thus releasing the adsorbed nitrogen. It is then ready for another cycle of producing oxygen-enriched air. Using two adsorbent vessels allows for near-continuous production of the target gas.