Salinity History of the Earth’s Ocean
Salinity refers to the total quantity of dissolved salts in water and is normally about 35 parts per thousand (‰) in today’s ocean. Due to problems with making accurate measurements of total salts, salinity is now normally expressed as a ratio of the electrical conductivity of the seawater to that of a standard concentration of KCl solution. The concentration of the standard solution is set such that the ratio of the approximate average salinity of the ocean today is equal to 35. The previous concentration value (‰) is thus unnecessary, but it is still widely used to highlight the basic meaning of the term. The relative proportions of the dissolved constituents are approximately constant, so the amount of Cl−, the major component, is a proxy for salinity. Salinity history refers to past changes in the amount of dissolved salts in sea water over geologic time.
Salinity is an important environmental variable affecting chemical balances and osmotic pressures in all...
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