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Measurements of primary productivity in the ocean can be made using this ratio. The concentration of oxygen dissolved in seawater varies according to biological processes (photosynthesis and respiration) as well as physical processes (air-sea gas exchange, temperature and pressure changes, lateral mixing and vertical diffusion).
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.
The solubility of gas obeys Henry's law, that is, the amount of a dissolved gas in a liquid is proportional to its partial pressure. Therefore, placing a solution under reduced pressure makes the dissolved gas less soluble. Sonication and stirring under reduced pressure can usually enhance the efficiency.
Warmer water also raises oxygen demand from living organisms; as a result, less oxygen is available for marine life. [40] Studies have shown that oceans have already lost 1-2% of their oxygen since the middle of the 20th century, [41] [42] and model simulations predict a decline of up to 7% in the global ocean O 2 content over the next hundred ...
However, for aqueous solutions, the Henry's law solubility constant for many species goes through a minimum. For most permanent gases, the minimum is below 120 °C. Often, the smaller the gas molecule (and the lower the gas solubility in water), the lower the temperature of the maximum of the Henry's law constant.
Water becomes less dense as its temperature increases and the distance between its molecules expands, but more dense as the salinity increases, since there is a larger mass of salts dissolved within that water. [15] Further, while fresh water is at its most dense at 4 °C, seawater only gets denser as it cools, up until it reaches the freezing ...
In the ocean by volume, the most abundant gases dissolved in seawater are carbon dioxide (including bicarbonate and carbonate ions, 14 mL/L on average), nitrogen (9 mL/L), and oxygen (5 mL/L) at equilibrium at 24 °C (75 °F) [122] [123] [124] All gases are more soluble – more easily dissolved – in colder water than in warmer water. For ...
Depressurisation causes inert gases, which were dissolved under higher pressure, to come out of physical solution and form gas bubbles within the body. These bubbles produce the symptoms of decompression sickness. [17] [52] Bubbles may form whenever the body experiences a reduction in pressure, but not all bubbles result in DCS. [53]