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  2. Oxygen cycle - Wikipedia

    en.wikipedia.org/wiki/Oxygen_cycle

    The oxygen cycle is the biogeochemical cycle of oxygen atoms between different oxidation states in ions, oxides, and molecules through redox reactions within and between the spheres/reservoirs of the planet Earth. [1] The word oxygen in the literature typically refers to the most common oxygen allotrope, elemental/diatomic oxygen (O 2), as it ...

  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. Oxygen - Wikipedia

    en.wikipedia.org/wiki/Oxygen

    Oxygen is the third most abundant chemical element in the universe, after hydrogen and helium.[67] About 0.9% of the Sun's mass is oxygen.[18] Oxygen constitutes 49.2% of the Earth's crustby mass[68]as part of oxide compounds such as silicon dioxideand is the most abundant element by mass in the Earth's crust.

  5. Ecosystem respiration - Wikipedia

    en.wikipedia.org/wiki/Ecosystem_respiration

    Ecosystem respiration is the sum of all respiration occurring by the living organisms in a specific ecosystem. [1] The two main processes that contribute to ecosystem respiration are photosynthesis and cellular respiration. Photosynthesis uses carbon-dioxide and water, in the presence of sunlight to produce glucose and oxygen whereas cellular ...

  6. Natural environment - Wikipedia

    en.wikipedia.org/wiki/Natural_environment

    The oxygen cycle is the movement of oxygen within and between its three main reservoirs: the atmosphere, the biosphere, and the lithosphere. The main driving factor of the oxygen cycle is photosynthesis, which is responsible for the modern Earth's atmospheric composition and life.

  7. Photosynthesis - Wikipedia

    en.wikipedia.org/wiki/Photosynthesis

    Photosynthesis (/ ˌfoʊtəˈsɪnθəsɪs / FOH-tə-SINTH-ə-sis) [ 1 ] is a system of biological processes by which photosynthetic organisms, such as most plants, algae, and cyanobacteria, convert light energy, typically from sunlight, into the chemical energy necessary to fuel their metabolism.

  8. Marine biogeochemical cycles - Wikipedia

    en.wikipedia.org/wiki/Marine_biogeochemical_cycles

    The word oxygen in the literature typically refers to molecular oxygen (O 2) since it is the common product or reactant of many biogeochemical redox reactions within the cycle. [37] Processes within the oxygen cycle are considered to be biological or geological and are evaluated as either a source (O 2 production) or sink (O 2 consumption). [36 ...

  9. Biogeochemistry - Wikipedia

    en.wikipedia.org/wiki/Biogeochemistry

    In particular, biogeochemistry is the study of biogeochemical cycles, the cycles of chemical elements such as carbon and nitrogen, and their interactions with and incorporation into living things transported through earth scale biological systems in space and time. The field focuses on chemical cycles which are either driven by or influence ...