1. Salt content and salinity

1.1 Major components

The total mass of salts dissolved in 1 kg of seawater can vary from one seawater to another (more than 40 g/kg of seawater in the Red Sea, less than 10 g/kg in certain regions of the Baltic Sea). On the other hand, the relative proportions of the main salts remain constant. This property is referred to as Dittmar's law. In practice, major constituents are those present in concentrations exceeding 1 mg.kg ^–1 . They are listed in table 1 .

The table 1 calls for the following comments:

• together, these species account for over 99.9% of the...