Why is the ocean salty? (2022)

Oceans cover a majority of the Earth’s surface and are filled with saltwater, which makes up about 97% of all water on Earth. The amount of salt in the ocean is so vast that if it were spread evenly on land, it would create a layer over 500 feet thick. The salt in the ocean comes from rocks on land, which are eroded by rainwater that carries dissolved salts and minerals into streams, rivers, and eventually the sea. While some ions are used by organisms and removed from the water, chloride and sodium make up over 90% of the dissolved ions in seawater. The salinity of seawater is about 35 parts per thousand, meaning 3.5% of its weight is from dissolved salts. In a cubic mile of seawater, there can be up to 25 pounds of gold and 45 pounds of silver, but considering the immense size of a cubic mile, alchemy on seawater is not practical.

https://www.usgs.gov/faqs/why-ocean-salty

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