There are various salts dissolved in seawater. In addition to sodium chloride (the scientific name of salt), there are other chemical components such as magnesium chloride, magnesium carbonate, potassium, sodium, etc., nearly 100 kinds of salts of major and trace elements.
The main source of salt in sea water is weathering materials of crustal rocks and volcanic eruptions for billions of years. The surface rocks are washed and eroded by the water flow, and the salt inside is continuously dissolved in the water; These waters continue to converge into a big river, rushing into the sea.
Scientists have found that the global rivers transport 5.5 billion hectares of dissolved salt to the oceans every year. As the water evaporates, the salt in the sea water gradually deposits. For a long time, the salt has accumulated more and more, so the sea water becomes salty. In addition, the eruption of submarine volcanoes and magma overflow will also increase the ocean salinity.