Why is the sea salty?

Of course the sea is salty. Everyone knows that. But, I found myself sitting with two clever people recently when the question came up, and none of us really knew. Why is some water really salty? Why are there salt lakes in the middle of an enormous land mass? Why?

We formulated a couple of theories involving evaporation or rocks falling into the sea and getting knocked about a bit, eventually to the point where some sodium bicarbonate popped out. Nothing was satisfactorily robust, so, I decided to find out.

This is for your benefit as much as mine. For that dinner party. You know.
The salt in the sea comes from:
  • Weathering of continents
  • Hydrothermal vents, and
  • Submarine volcanoes

It's pretty cool! And you can read more here: Why is the sea salty?