Why is there so much salt in the oceans if fresh rivers flow into them?

There are, as you know, two types of reservoirs - fresh and salty. The oceans and seas have a very high amount of sodium chloride, which makes them undrinkable. The salt level of reservoirs is different, but if you look at the average, you will see that about 35 grams of sodium chloride are dissolved in each liter of water. But where did salt come from in the oceans?

For a long time, people could not find the answer to this question, because if fresh rivers flow into the ocean, how does it remain salty? The version was first proposed by Edmund Halley at the beginning of the 18th century - he suggested that it was all about the evaporation of water. That is, in his opinion, if there is salt in a certain amount in many places on the dry part of the Earth, then rivers and lakes also contain it, only in a minimal amount.

Edmund Halley was an English geophysicist, astronomer, meteorologist, physicist, mathematician and demographer. He was also a Member of the Royal Society of London, a foreign member of the Paris Academy of Sciences.

But the seas are stationary, there is no source from them. The surface evaporates a large amount of water, and the salt concentration gradually increased in the remaining one. And that's how the world's oceans became salty, he suggested.

That's what Edmund Halley thought. And this theory held for several centuries.

But later scientists questioned Halley's theory. If he were right, then the salinity of the oceans and seas should have increased at least a little over three centuries. But this figure remains stable. The rates vary between seas, but the rates for each sea were within the margin of error during the observations and did not increase.

But after a thorough study of the indicators of salt content in rivers, the theory was revised.

Fresh waters contain other salts - carbonates. There are very few chlorides in them, so they carry carbide impurities into the ocean. Most of the carbides are consumed by marine life, and a smaller part settles to the bottom. And these impurities cannot create the salt suspension that is in the sea.

Modern hypothesis links ocean salinity to volcanic activity

In the early stages of the formation of our planet, volcanic activity was high - emissions with precipitation fell into the ocean water and it became acidic, which made it a rather aggressive environment.

Acidified water affected the minerals of the bottom and the land in contact with it and gradually corroded them. In basalts and other rocks, the environment was alkaline. As a result of the reaction, salt appeared, dissolving in the oceans.

Approximately 500 million years ago, high volcanic activity on Earth ceased and came to modern levels.

The water continued to dissolve the basalts for some time until its acidity decreased. The salt that had already formed had nowhere to go and it remained in the water. According to this theory, that is why its statistical average does not change. The reactions that led to the formation of sodium chloride in it stopped.