SALINITY

The most important salt found in sea water is sodium chloride (NaCl), widely used for domestic and culinary purposes, but there are plenty more. The salinity of water, i.e. the quantity of salts in the water, is expressed in 0/00 or in g/liter. The mean salinity of the Earth's oceans is around 350/00, or approximately 35 g salts/liter. Whatever its salinity, sea water boasts one remarkable property: the proportion of each element is constant.

Desalinated water does not therefore contain less of one or more salts, but the combination of salts is present in a lower concentration.

The salinity of sea water varies according to longitude. It is at its highest in open seas in the tropics, it is lower near coasts and after heavy rain, and it is at its lowest near the poles (due to the influence of melting snow).