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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.
Marine chemistry, also known as ocean chemistry or chemical oceanography, is the study of the chemical composition and processes of the world’s oceans, including the interactions between seawater, the atmosphere, the seafloor, and marine organisms. [2]
The most abundant dissolved ions in seawater are sodium, chloride, magnesium, sulfate and calcium. [16] Its osmolarity is about 1000 mOsm/L. [17] Small amounts of other substances are found, including amino acids at concentrations of up to 2 micrograms of nitrogen atoms per liter, [18] which are thought to have played a key role in the origin ...
CaCO 3 is supersatured in the great majority of ocean surface waters and undersaturated at depth, [10] meaning the shells are more likely to dissolve as they sink to ocean depths. CaCO 3 can also be dissolved through metabolic dissolution (i.e. can be used as food and excreted) and thus deep ocean sediments have very little calcium carbonate. [16]
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) [124] [125] [126] All gases are more soluble – more easily dissolved – in colder water than in warmer water. For ...
The Great Oxidation Event (GOE) or Great Oxygenation Event, also called the Oxygen Catastrophe, Oxygen Revolution, Oxygen Crisis or Oxygen Holocaust, [2] was a time interval during the Earth's Paleoproterozoic era when the Earth's atmosphere and shallow seas first experienced a rise in the concentration of free oxygen. [3]
However, most marine primary production comes from organisms which use photosynthesis on the carbon dioxide dissolved in the water. This process uses energy from sunlight to convert water and carbon dioxide [4]: 186–187 into sugars that can be used both as a source of chemical energy and of organic molecules that are used in the structural ...
Sea slugs respire through a gill (or ctenidium). Aquatic respiration is the process whereby an aquatic organism exchanges respiratory gases with water, obtaining oxygen from oxygen dissolved in water and excreting carbon dioxide and some other metabolic waste products into the water.