The salinity of the sea was included into sayings and proverbs, about it sing in songs, the reasons of it the phenomenon speak in ancient legends. Scientists disagree concerning when and as the sea became salty. Some consider that it occurred long ago when on Earth volcanoes did not calm down yet and there was only primary ocean, and others consider that the sea became salty relatively recently, and process took billions of years.
The salty sea, but not as, for example, the food cooked by the person. It very strongly salty, even bitter. When the ship with sailors was wrecked, a lot of things depended on whether it managed to the escaped people to catch fresh water. Without it they perished, from the sea without special water desalters it is impossible to extract it. Some scientists believe that the salinity of the ocean was established still long before life on Earth arose. But they are opposed by others. They say that salt gets to the seas from river water. Only it seems that water in the rivers fresh, just salt in it contains less, than in the sea, approximately by 70 times. But the seas and oceans have the huge area, water from their surfaces evaporates, and salt remains. Therefore sea and salty. By approximate calculations of scientists, in a year from the rivers about 2,834,000 thousand tons of substances which support salt level at the previous level get to the ocean. In total it makes no more, than one sixteen-million part from all salt which is contained in the seas. If to consider that the rivers deliver such amount of substance in the sea already for a long time it is, more, than 2 billion years, then this theory it is really very probable. Gradually substance from the rivers quite could salt the seas. However, at all not all substance is dissolved in water. Its rather most part settles on a bottom and, being exposed to the huge pressure of water, connects to a sea landscape. Other scientists are sure that water in the sea was salty almost from the very beginning. The reason is that at the time of existence of primary ocean liquid in it only on? consisted of water, not less than 15% of structure there was a carbonic acid, and another 10% - it were various substances accompanying eruptions of volcanoes. A considerable part of what left volcanoes dropped out in the form of acid rains, substances reacted with each other, mixed up, bitterish and salty solution as a result turned out. Such theory is spoken well by different salt structure of the rivers and seas. In river water limy connections and soda prevail, there is a lot of calcium. The ocean contains mainly chlorides, that is salts formed of hydrochloric acid, sodium. On this argument the supporters of the theory of gradual salinization of the sea claim that the quality of sea water was changed by various microorganisms and animals who absorbed calcium and carbonates while chlorides were not necessary to them. From here such imbalance in the modern ocean. But this assumption of supporters has some. Most of oceanologists adheres to the theory that the sea received salt from volcanic breeds, and it occurred at very early age of the planet, and further salinization of the sea did not play in the general level of salt of a big role.