QuestionOceanography / salinity
The salt in sea water comes from:
- (a) rain.
- (b) chemical exchange between sea water and its substratum as well as hydrothermal emissions.
- (c) evaporation of water and concentration of dissolved salts.
- (d) mixing of different density waters during natural warm and cold current movements.
Answer: (b) chemical exchange between sea water and its substratum as well as hydrothermal emissions.
Sea salt comes from rock weathering brought by rivers, exchange with the sea floor and hydrothermal emissions (Cl⁻ and other volatiles from vents and volcanoes). Evaporation only concentrates salt; it does not supply it. Rain is nearly salt-free.