Why is salt water in the sea? This question at least once in a lifetime (or rather, in childhood) was asked by each of us.
"Water whetsts a stone." This proverb is very true. All over the world there is no solvent stronger than water. It is able to erode salts and acids, easily copes with stones and huge rocks.
Rain streams leach the hardest rocks and wash them off into the water. Salt, accumulating in the water, makes it bitterly salty.
But why do rivers remain fresh?
Scientists name several reasons. Consider the basic theories that today, experts who study sea water.
Why is salt water in the sea? Theory One.
All impurities entering the water sooner or later end up in the seas and oceans. Why is salt water in the sea ? Because the rivers are also salty. However, their salts are 70% less than in the ocean. Instruments register it, and the taste of the river water seems fresh. Running water from rivers flows into the ocean, salts accumulate there. The process has been going on for more than two billion years. This time is more than enough to “salt” a huge amount of water. Water gradually evaporates, rains, and returns to the ocean. Salts and other elements remain unchanged: they do not evaporate, but only accumulate.
A good confirmation of this theory are lakes that have no runoff: they are also salty.
For example, the water of the Dead Sea (essentially a huge drainage lake) contains such an amount of salt that it pushes any body to the surface.
This lake is the lowest point on the planet, which, moreover, is located in a hot place. Due to the climate and fumes, scientists say, the salinity of the Dead Sea has reached almost 40%. Neither fish nor plants are found in it. Even outwardly, water resembles an oily substance. And at the bottom of the lake instead of the usual silt - salt.
This theory, which explains why the water in the sea is salty, has one significant drawback. It does not take into account that in the composition of river water are mainly salts of carbonic acid, and in sea water - sodium chloride (ordinary salt).
Why is salt water in the sea? Second theory.
According to her, initially the water in the ocean was not salty, but acidic. Why? Because at the time of the Earth’s birth, the atmosphere literally boiled. Volcanoes “threw” a lot of chemical elements into it, acid rain spilled. All this settled on the bottom of the newborn oceans, making it acidic. Gradually, the rivers were carried into the ocean by eroded rocks that reacted with acid. As a result, salts were released, which made the water salty. Carbonates also stood out, but they were very actively used and are used by marine animals, who build shells, skeletons, and shells with their help.
Once upon a time, the process stabilized, but the water in the seas remained salty. She remains so today.
Both theories hold true, but none of them exactly explains why there is different water in the sea and rivers. In some places, these hypotheses complement each other, and in some places they refute.
Perhaps very soon a new theory will appear that will give an exhaustive answer to the question of interest to all people on Earth.