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  2. Aquatic respiration - Wikipedia

    en.wikipedia.org/wiki/Aquatic_respiration

    Countercurrent flow occurs when deoxygenated blood moves through the gill in one direction while oxygenated water moves through the gill in the opposite direction. This mechanism maintains the concentration gradient thus increasing the efficiency of the respiration process as well and prevents the oxygen levels from reaching an equilibrium ...

  3. Marine biogeochemical cycles - Wikipedia

    en.wikipedia.org/wiki/Marine_biogeochemical_cycles

    Water is the medium of the oceans, the medium which carries all the substances and elements involved in the marine biogeochemical cycles. Water as found in nature almost always includes dissolved substances, so water has been described as the "universal solvent" for its ability to dissolve so many substances.

  4. Water cycle - Wikipedia

    en.wikipedia.org/wiki/Water_cycle

    Water cycle showing human influences and major pools (storages) and fluxes. [19] The water cycle describes the processes that drive the movement of water throughout the hydrosphere. However, much more water is "in storage" (or in "pools") for long periods of time than is actually moving through the cycle.

  5. Water aeration - Wikipedia

    en.wikipedia.org/wiki/Water_aeration

    Water aeration is the process of increasing or maintaining the oxygen saturation of water in both natural and artificial environments. Aeration techniques are commonly used in pond, lake, and reservoir management to address low oxygen levels or algal blooms.

  6. Oxygen cycle - Wikipedia

    en.wikipedia.org/wiki/Oxygen_cycle

    The oxygen cycle demonstrates how free oxygen is made available in each of these regions, as well as how it is used. 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]

  7. Fish gill - Wikipedia

    en.wikipedia.org/wiki/Fish_gill

    The concentration of oxygen in water is lower than air and it diffuses more slowly. In a litre of freshwater the oxygen content is 8 cm 3 per litre compared to 210 in the same volume of air. [7] Water is 777 times more dense than air and is 100 times more viscous. [7] Oxygen has a diffusion rate in air 10,000 times greater than in water. [7]

  8. Oxygenation - Wikipedia

    en.wikipedia.org/wiki/Oxygenation

    Oxygen saturation (medicine), The percent of hemoglobin saturated by oxygen, usually in arterial blood. Water oxygenation, the process of increasing the oxygen saturation of the water; Dioxygen complex, the chemical details of how metals bind oxygen; Great Oxygenation Event, an ancient event that led to the rise of oxygen within our atmosphere

  9. Respiration (physiology) - Wikipedia

    en.wikipedia.org/wiki/Respiration_(physiology)

    In mammals, physiological respiration involves respiratory cycles of inhaled and exhaled breaths. Inhalation (breathing in) is usually an active movement that brings air into the lungs where the process of gas exchange takes place between the air in the alveoli and the blood in the pulmonary capillaries.