HaitiLibre Quiz

Seas and Oceans 3.1 WORLD

Difficulty Level: N3 Hard
This advanced level quiz doesn't just skim the surface; it immerses you in the invisible cogs of the oceanic machine. From solitary waves to extreme hydrostatic pressures, prepare yourself for total immersion where only a solid scientific and maritime culture will allow you to keep your head above water.
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Where does ocean salinity mainly come from on a geological time scale ?

100% of players answered correctly.

THE CORRECT ANSWER: Erosion of continental rocks and underwater volcanic degassing

Ocean salinity is the result of a process spanning billions of years. Mainly, rainwater, slightly acidic because of atmospheric CO2, erodes terrestrial rocks, releasing ions (notably sodium and magnesium) transported by rivers to the oceans.The other major source is underwater volcanic activity and hydrothermal vents, which release minerals including chloride. Once in the ocean, these ions accumulate because, during evaporation, only pure water rises, leaving the salts behind.This cycle has reached a state of stationary equilibrium for around 1.5 billion years, where new inputs compensate for the precipitation of salts in marine sediments. The average salinity is 35 g/L, but it varies according to latitude: it is higher in subtropical zones with high evaporation and lower at the poles due to melting ice and precipitation.