We all know that water is essential for life, but not all water has the same characteristics and can be drunk. 70% of planet Earth is water, but only 2.5% of the total is fresh water. The remaining 97.5% is salt water, and mostly appears in seas and oceans. The difference between fresh water and salt water is found in the chemical composition of each of them.
The origin of the seas and oceans
It all started about 4,600 years ago when the Earth was still forming. In those days, the Earth was a great red-hot mass that was nothing like its current appearance. Although, little by little, the planet was cooling on the outside, the rocks that were inside the planet were still hot and undergoing physical and chemical transformations. During that time, through geysers, volcanic eruptions and cracks in the earth’s crust , volatile and light gases, such as water vapor, escaped that formed the primitive atmosphere. When water vapor cooled outside the Earth’s interior, it condensed and gave way to clouds and rain. The rain that fell for hundreds of years It filled the depressions that were in the land and was forming the first seas and oceans that with time would end up being what we know today.
At this point, we know how the seas and oceans formed, but how did they become salty? The answer is very simple, salt water has salt , salt like the one we put in food. Although the answer of how that salt got to the seas and oceans is not so simple, we are going to explain it now.
First of all, it is very important to know what salt is. The salt or sodium chloride, chemically speaking, is a substance that is composed of two elements: chlorine (Cl) and sodium (Na)and it is these two elements together that make us feel the salty taste of water. Salt is naturally found in minerals and rocks in a solid state, but at the same time it tends to dissolve in water when it is present. To check this, we can do a little experiment at home by pouring several tablespoons of salt into a glass of water (the salt will disappear and then the water will be salty). Going back to the story of the beginning, we might recall that the early atmosphere contained water vapor and other gases. Well, some of these gases, such as carbon dioxide (CO2) when combined with water vapor, form carbonic acid that falls in the form of rain. The rain erodes and erodes the rock and dissolves the salt it contains. In this way the water becomes salty.
In water there are also other elements that increase its salinity , such as potassium (K), magnesium (Mg), sulfate, calcium (Ca), bicarbonate or bromine (Br). These elements also come from rocks and magma or lava (magma on the earth’s surface) from volcanoes.
The salinization process of the oceans began millions of years ago and continues even today. Volcanic eruptions, salts from river water, erosion of terrestrial and marine rocks, and evaporation from the oceans keep the water salty.
Currently, marine waters are characterized by having a salinity of 35 g for each liter of water . On the other hand, the salinity of the oceans is not the same everywhere since in areas affected by the melting of the north and south poles, river mouths or by factors such as evaporation, rain, wind or sea currents. they can make the salinity higher or lower in those waters. The water that bathes the poles, which is less salty, is not the same as that of the Baltic Sea, which receives water from numerous rivers, or the Mediterranean Sea, which has a high concentration of salt due to its closed basin, receives high temperatures and has high evaporation. However, the saltiest sea in the world is the Dead Sea.
There are some seas that stand out for their high concentration of salt in the water, such as the Dead Sea , which is located between Israel, Palestine and Jordan. The Dead Sea has a salinity of 350 g of salt per liter , this is ten times more than the average salinity of the oceans.
Due to its high salinity, life cannot develop in it. It is estimated that there could be about 40 million tons of salt inside. Part of its salinity is also due to the presence of magnesium, calcium, potassium and bromine. In addition, the high concentration of salt makes the water have a higher density than water (1240 kg / m 3 ) and for that reason, a person can float perfectly in its waters, in fact, it is almost impossible to submerge in them.