Why is the water in the sea salty?

Posted on Mar 13, 2022      221

Why do you think the water in the sea is salty and the water in the river is fresh? After all, everyone knows about the water cycle in nature. All water that falls as precipitation is fresh and it still flows into the seas and oceans.

For a long time it was believed that the sea salts the rivers, which only to human taste seem fresh. In fact, they too are salty, only 70 times weaker than the ocean. It is simply that on its way to the sea, the river water washes the salts out of the rocks through which the river bed runs.

As it enters the world’s oceans, the planet’s rivers add one sixteen-millionth of the salt each year. The water then evaporates, again precipitating on land to add a new salt pinch to the ocean again. This theory was well supported by the salinity of the water in the drainless lakes.

So it turns out that the seas were originally as low-saline as the rivers, and only over billions of years did the water in them gain a characteristic taste. But there is one enormous gap in this theory: the composition of salts in rivers and seas is different: in the sea, chlorides (salts of hydrochloric acid) prevail, and in rivers, carbonates (salts of carbonic acid) prevail.

Today, however, a growing number of scientists believe that the seas and oceans were as salty from the beginning of their formation as they are now because of volcanic activity. It is assumed that the water of the primary ocean was a condensate of volcanic gases, which are 75% water, 15% carbon dioxide, and the remaining 10% are methane, ammonia, sulfur compounds, “acid fumes” containing chlorine, fluorine, bromine and inert gases. A large part of the products of the eruption were spilled on the ground by acid rains and reacted with the rocks of the future sea floor, leaving behind a salty solution.

This theory is supported because the concentration of salt in the water of the open ocean is always the same. The constancy of the salt composition was called the Dietmar Law, after the English chemist who proved this important property of seawater in 1884.