We all know that sea and ocean water is salty, but do we know why this is so? If the rivers that flow into the sea are freshwater, why is the ocean salty? About 4.650 million years ago the Earth was made up of a great hot mass, the continents and oceans had not yet formed and, logically, living beings did not yet exist. Once it cooled down, gases began to rise through geysers into the atmosphere, basically water vapour. Thanks to the condensation, they turned into rainwater. This rain is what ended up forming the rivers and oceans due to their constant fall, but these were freshwater. So when did the salinization process take place?

Here we want to explain why the sea is salty and how that transformation took place. Do not miss it!

What is sea water?

It is a question that we do not usually ask ourselves, but its answer is not less interesting for that. Sea water is one of the most fascinating land elements. In the seawater compound there are different components that make it unique, from materials that have been dissolved belonging to the earth’s crust to products and fluids released by an infinity of marine organisms. All the elements that make it up are necessary for life to exist that inhabits the temperate waters of the seas or the icy liquid of the oceans.

Salinity, temperature, gases that accumulate there, nutrients and their pH are other important factors for one type of life or another to develop in that space.

How does the salinization process take place?

The salinity of the water is produced by the different minerals that make up this extraordinary element. Basically, the salinization of water occurs thanks to the dissolution of chlorine, sodium, sulphur, magnesium, calcium and potassium.

The process has taken place over millions of years of filtration and dissolution of components from the waste and fluids of marine organisms and the breakdown of igneous rocks caused by wear and erosion.

Finally, the existence of large amounts of sodium and chlorine ions cause the formation of sodium chloride or salt. These elements have been enriching, with the minerals mentioned above, the composition of sea water, finally turning it salty.

Studying salt water

Throughout the 20th century, a large part of the scientific community has devoted its efforts to the study of the salinity of water, although, unfortunately, all the components that make up seawater have not yet been discovered.

This problem is due to the lack of adequate methods for such measurement and the great oceanic extension that makes it extremely difficult to carry out completely reliable evaluations.

What is known is that seawater is made up of a great variety of chemical elements, at least 72 located in different quantities important enough to be able to be measured optimally.

What is sea water made of?

Next, we present a summary of some elements that make up water and make it salty:

  • Chlorine (Cl): 19.3% per thousand parts of water.
  • Sodium (Na): 10.7% per thousand parts of water.
  • Sulphate (SO4): 2.7% per thousand parts of water.
  • Magnesium (Mg): 1.3% per thousand parts of water.
  • Calcium (Ca): 0.4% per thousand parts of water.
  • Potassium (K): 0.4% per thousand parts of water.
  • Bicarbonate (HCO3): € 0.15 per thousand parts of water.
  • Bromide (Br-1): 0.07% per thousand parts of water.
  • Other elements: 0.06% per thousand parts of water.
  • Total salinity: 35.08%


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