Almost each of us, having carelessly opened our mouths while swimming in the sea and taken a sip of water, wondered why the sea is salty? Of course, you can be like the ancient Greeks, who believe that the waters of the seas and oceans are the tears of Poseidon. But now they don’t believe in fairy tales, and a strictly scientific substantiation of the reasons for the appearance of salt in sea waters is required.

Theories of sea salinity

Researchers on this long-standing problem fall into two camps, proposing specific theories.

The salinity of the seas gradually increased

This was facilitated by the natural water cycle. Precipitation, acting on the rocks, washed out minerals from it, which ended up in river systems. And from the rivers, water saturated with salts was already flowing into the seas. The river flows themselves also contributed to the leaching of salts from soils and rocks.

Then the tireless Sun began to work. Under its hot influence, water evaporated, no longer containing salts. Distilled moisture fell as rain and snow on the surface of the planet and continued its work of saturating the seas with salts.

The process continued for many millions of years, salt accumulated in sea waters, acquiring exactly the consistency that we now observe. Everything is simple and quite logical. However, there is some inconsistency in this theory.

For some reason Over the past half a billion years, the concentration of salts in sea waters has not changed. But rainfall and rivers are as active as ever. This discrepancy can be explained as follows. Salts delivered by rivers to the subsoil of the sea do not dissolve in them, but settle on the bottom surfaces. From them various rocks and rocky formations are formed.

Sea waters have been salty from the very beginning

During the formation of the earth's crust, powerful volcanic activity was observed. Thousands of volcanoes emitted gigantic amounts of all kinds of substances into the atmosphere, among which were:

• chlorine;
• bromine;
• fluorine.

Acid rains constantly fell on the earth's surface, contributing to the birth of seas.

Their oxidized waters interacted with rocks and pulled out from them:

• potassium;
• sodium;
• magnesium;
• calcium.

As a result, salts were obtained, with which the waters were saturated. But 500 million years ago this process ended.

More interesting versions of salt formation in the seas

The search for versions of the appearance of salty and fresh waters does not stop. At this time, two are the most interesting.

1. Our planet was formed exactly in this form - salty seas and fresh rivers. If it were not for the river currents, the rivers could also become salty, but fortunately, the seas cannot flow into them.
2. Animals contributed. For a long time, the waters were salty everywhere. But animals very actively consumed it from rivers and lakes in order to obtain the necessary chemical elements for the development of their organisms. Over many hundreds of millions of years, the rivers have lost all their sodium chloride reserves. But this version is more entertaining.

Features of sea water

For people, fresh water is familiar and its beneficial properties are obvious. But sea waters also have their own characteristics.

1. It is absolutely not suitable for drinking. The content of salts and other minerals in it is very high. They can only be removed from the body with more water. But if such water is desalinated, then it is quite drinkable.
2. In some countries, sea salt water is used for domestic needs. For example, in drainage sewer systems.
3. The benefits of sea water for treatment have long been known. It is used in the form of baths, rinses, and inhalations. This helps fight respiratory diseases and relieves muscle tension. Water with a high salt content also exhibits antibacterial properties.

The salinity of the waters of some known seas is as follows (at 0/00):

• Mediterranean – 39;
• Black – 18;
• Karskoe – 10;
• Barentsevo – 35;
• Red – 43;
• Caribbean - 35.

Such a disproportionate salt content in the waters of different seas is influenced by specific factors:

• drainage of rivers and streams flowing into them;
• precipitation water;
• transformation of sea ice;
• vital activity of all kinds of marine organisms;
• plant photosynthesis;
• bacteriological activity.

Now you know why the sea is salty!

Why is the sea salty, and where does the salt come from? This is a question that has interested people for a long time. There is even a folk tale about this.

As folklore explains

Whose legend this is, and who exactly came up with it, is no longer known. But among the peoples of Norway and the Philippines it is very similar, and the essence of the question of why the sea is salty is conveyed in the fairy tale as follows.

There were two brothers - one rich, and the other, as usual, poor. And no, to go and earn bread for his family - the poor man goes for alms to his stingy rich brother. Having received a half-dried ham as a “gift”, the poor man, in the course of some events, falls into the hands of evil spirits and exchanges this very ham for a stone millstone, modestly standing outside the door. And the millstone is not simple, but magical, and can grind whatever your heart desires. Naturally, the poor man could not live quietly, in abundance, and not talk about his miraculous find. In one version, he immediately built a palace for himself on one day, in another, he threw a feast for the whole world. Since everyone around him knew that just yesterday he had lived poorly, those around him began to ask questions about where and why. The poor man did not consider it necessary to hide the fact that he had a magic millstone, and therefore many hunters appeared to steal it. The last person to do so was the salt merchant. Having stolen the millstone, he did not ask to grind money, gold, or overseas delicacies for him, because having such a “device”, he could no longer engage in the salt trade. He asked to grind salt for him so that he would not have to swim across the seas and oceans for it. A miracle millstone started up and ground so much salt that it sank the unfortunate merchant’s ship, and the millstone fell to the bottom of the sea, continuing to grind salt. This is how people explained why the sea is salty.

Scientific explanations of the fact

The main source of salts in the seas and oceans are rivers.

Yes, those rivers that are considered fresh (more correctly, less salty, because only the distillate is fresh, that is, devoid of salt impurities), in which the salt value does not exceed one ppm, make the seas salty. This explanation can be found in Edmund Halley, a man known for the comet named after him. In addition to space, he studied more mundane issues, and it was he who first put forward this theory. Rivers constantly bring huge amounts of water along with small impurities of salts into the depths of the sea. There the water evaporates, but the salts remain. Perhaps earlier, many hundreds of thousands of years ago, ocean waters were completely different. But they add another factor that may explain why the seas and oceans are salty - volcanic eruptions.

Chemicals from volcanoes bringing salt to the sea

During times when the earth's crust was in a state of constant formation, there were frequent emissions of magma with incredible amounts of different elements to the surface - both on land and under water. Gases, indispensable companions of eruptions, mixed with moisture and turned into acids. And they, in turn, reacted with the alkali of the soil, forming salts.

This process is still happening now, because seismological activity, although much lower than it was millions of years ago, is still present.

In principle, other facts explaining why the water in the sea is salty have already been studied: salts enter the seas from the soil through movement by precipitation and winds. Moreover, in each open body of water the chemical composition of the earth’s main liquid is individual. To the question of why the sea is salty, Wikipedia answers in the same way, only emphasizing the harm of sea water for the human body as drinking water, and its benefits when taking baths, inhaling, and the like. It’s not for nothing that sea salt is so popular, which is even added to food instead of table salt.

Unique mineral composition

We have already mentioned that the mineral composition is unique in each body of water. Why the sea is salty and how salty it is is determined by the intensity of evaporation, that is, the wind temperature on the reservoir, the number of rivers that flow into the reservoir, the richness of flora and fauna. So, everyone knows what kind of sea is the Dead Sea, and why it is called that.

Let's start with the fact that it is incorrect to call this body of water a sea. It is a lake because it has no connection with the ocean. It was called dead because of the huge proportion of salts - 340 grams per liter of water. For this reason, no fish can survive in a body of water. But as a health resort, the Dead Sea is very, very popular.

Which sea is the saltiest?

But the right to be called the saltiest belongs to the Red Sea.

There are 41 grams of salts in a liter of water. Why is the Red Sea so salty? Firstly, its waters are replenished only by precipitation and the Gulf of Aden. The second one is also salty. Secondly, the evaporation of water here is twenty times higher than its replenishment, which is facilitated by its location in the tropical zone. If it were a little further south, closer to the equator, and the amount of precipitation characteristic of this zone would dramatically change its content. Due to its location (the Red Sea is located between Africa and the Arabian Peninsula), it is also the warmest sea among all those on planet Earth. Its average temperature is 34 degrees Celsius. The whole system of possible climatic and geographical factors made the sea what it is now. And this applies to any body of salt water.

The Black Sea is one of the unique compositions

For the same reasons, one can single out the Black Sea, whose composition is also unique.

Its salt content is 17 ppm, and these are not entirely suitable indicators for marine inhabitants. If the fauna of the Red Sea amazes any visitor with its diversity of colors and life forms, then do not expect the same from the Black Sea. Most of the “settlers” of the seas cannot tolerate water with less than 20 ppm salts, so the diversity of life is somewhat reduced. But it contains many useful substances that contribute to the active development of single- and multicellular algae. Why is the Black Sea half as salty as the ocean? This is primarily due to the fact that the size of the territory from which river water flows into it exceeds the sea area itself by five times. At the same time, the Black Sea is very closed - it is connected to the Mediterranean only by a thin strait, but otherwise it is surrounded by land. The salt concentration cannot become very high due to intensive desalination by river waters - the first and most important factor.

Conclusion: we see a complex system

So why is the water in the sea salty? This depends on many factors - river waters and their saturation with substances, winds, volcanoes, the amount of precipitation, the intensity of evaporation, and this, in turn, affects the level and diversity of living organisms in it, both representatives of flora and fauna. This is a huge system with a large number of parameters that ultimately make up an individual picture.

As you know, sea water is a solution of various salts, giving it a characteristic bitter-salty taste.


At the same time, rivers that flow into seas and oceans consist only of fresh water, the concentration of dissolved salts in which is significantly lower than in sea water. But how can this be, why do sea and river water contain such different amounts of dissolved substances? Let's find out what scientists think about this.

Version No. 1 – salt accumulated gradually

Rain or melt water is an almost pure distillate: it contains a minimal amount of substances collected during the fall in the atmosphere to the surface of the earth.

Absorbing into the soil and collecting in streams and then in rivers, water dissolves minerals, which are then carried with river water into the ocean. Evaporation from the surface of the ocean, which occurs much more intensely than on land, again raises clean, distilled water into the atmosphere, and salts remain in the ocean.

This process continues for billions of years, during which the concentration of salts in sea water has increased tenfold. This hypothesis is supported by the existence of salt lakes on the land surface that have never been in contact with the waters of the World Ocean. As a rule, these are closed reservoirs into which water only flows in the form of streams, but does not flow out.


True, this theory does not explain the difference between the composition of salts in sea and river water. Fresh water also contains various salts, but these are, as a rule, carbonates - carbonic acid salts, which are formed as a result of the breakdown of organic residues - fallen leaves, etc.

Sea water contains up to 80 different chemical elements and their compounds, but the predominant substance in it is sodium chloride, or ordinary table salt, which gives a characteristic salty taste. Where does table salt come from in the sea if it is not washed off the land? This question is answered by the second version proposed by scientists.

Version No. 2 – salt was in the water initially

Billions of years ago, when our planet was still very young, violent volcanic activity took place in its crust. Eruptions large and small were a daily occurrence.

A large amount of volcanic gases, which contained chlorine, bromine and fluorine in free form, were released into the atmosphere and waters of the World Ocean. The atoms of these elements reacted with water vapor and formed acid molecules, so in the initial period of its existence, sea water was not salty, but acidic.

These acids, having high chemical activity, reacted with metals contained in volcanic rocks - sodium, magnesium, potassium, etc. The compounds formed as a result of the reaction were the salts that gave the water its today’s “sea” taste.

The acids were almost completely neutralized, and the modern composition of sea water stabilized about 500 million years ago - a fact proven by studying the rocks of the sea and ocean floor.

How did it all really happen?

Most likely, both processes described above are to blame for the fact that sea water has become salty. The water of the World Ocean actually received its initial level of salts due to the active volcanic activity of the earth’s crust.

Today's salt levels are maintained by the leaching of minerals by rivers, as well as by the activities of numerous living organisms that use dissolved substances to build their cells.

Interesting fact: although sea water is completely undrinkable, the concentration of salt in it corresponds to the salt content in human blood plasma.

Daily bathing in sea water strengthens the body and helps fight many different diseases of the skin, respiratory tract, nervous system, etc.

Sea water has a not very pleasant salty and bitter taste, which makes it impossible to drink. But not every sea has the same salinity. When visiting the beach for the first time, a child often asks the question: why is the water salty? The question is simple, but it baffles parents. So, why is the water in the seas and oceans salty, what does the salinity of the water depend on.

Impact of the location of seas and oceans

If we take the planet’s seas, the water in each of them will differ in its composition. Experts say that closer to the northern regions, the salinity indicator increases. To the south, the percentage of salt content in sea water decreases. But here one thing should be remembered - ocean water is always much saltier than sea water, location does not affect this. And this fact cannot be explained by anything.

The salinity of water is due to the content of sodium and magnesium chlorides, as well as other salts. Alternatively, certain areas of land are enriched in deposits of these components, thereby differing from other regions. Frankly, this explanation is quite far-fetched, given sea currents, since salt levels should stabilize throughout the volume over time.

Reasons affecting the salt content in water

Scientists offer several explanations for the fact that the water in the seas and oceans is salty. Some people think that the high salt content is possible due to the evaporation of water from rivers flowing into the seas. Others argue that the salinity is nothing more than the result of water washing away stones and rocky areas. There are those who compare this phenomenon with the result of the action of volcanoes.

Many are skeptical about the idea that salts enter the seas with river waters. But no one denies that river water still contains salt, although not in such quantities as in the ocean.

Consequently, when river water enters the sea, a certain desalination occurs, but after the evaporation of river moisture, the salts remain in the sea. Impurities do not create such large volumes, but taking into account the duration of this process, the phenomenon is quite understandable. Salts accumulate at the bottom, being carried further by sea currents and giving the water bitterness.

Volcanoes also have their effect. When released, they carry a decent amount of various components, including salts. Volcanic activity was especially high during the formation of the Earth. Large amounts of acid were released into the atmosphere. There is an assumption that due to the effects of acid rain, the water in the seas was initially acidic. Interacting with calcium, potassium and magnesium, salt accumulations were formed.

There are a number of other reasons that can affect the percentage of salt content in water. This reason is associated with winds capable of bringing salts, with a soil composition capable of passing moisture through itself, saturating it with salts, salt-releasing minerals located under the ocean floor.

Where is the most salt found?

Liquid in the form of seawater makes up the largest amount on the planet. For this reason, many people seek to relax on the sea beaches when going on vacation. Surprisingly, the mineral composition of liquids from different seas differs from each other. And there are reasons for this. So, which sea is the saltiest?

The answer to this question is provided by research statistics. The Red Sea is rightfully the saltiest sea, containing forty-one grams of salts in each liter of its liquid. For comparison, a similar amount of water from the Black Sea contains only eighteen grams, the Baltic - only five.

The chemical table of the Mediterranean Sea reaches thirty-nine grams, slightly behind the Red Sea. Ocean waters have a salt content of thirty-four grams.
What is the secret of Red Sea leadership? On average, about one hundred millimeters of precipitation falls above its surface every year. This is an insignificant amount considering that evaporation per year reaches up to two thousand millimeters.

There is no influx of water into the Red Sea from the flowing rivers due to the lack of such; replenishment occurs exclusively due to precipitation and water resources of the Gulf of Aden, where the water is also salty.

Another reason is the mixing of waters. In the winter and summer seasons, there is a change in liquid layers. Only the upper layers of water undergo evaporation. The remaining salts sink to the bottom. For this reason, their number per liter of water is constantly growing.

Sometimes the Dead Sea is called the saltiest, in which the salt percentage per unit of water reaches more than three hundred grams. This level even affects the fact that fish cannot survive in this sea. But the features of this reservoir are such that it does not have access to the ocean, therefore, it is more logical to consider it a lake.

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Why is the sea salty?

“Why is the sea salty?” - one of children's favorite summer questions. In our new column “Why” we will regularly answer the most interesting questions of preschoolers and schoolchildren in clear and simple language, as well as hold exclusive competitions!

Why is the sea salty? Why does a hedgehog need needles? Why did they add “-s” to many words in the last century? Why do cats purr and what do they do? Is it possible to create a time machine according to the laws of physics? As a parent or teacher of primary and secondary schools, you will hear these questions more than once. We will be happy to answer them.

Why is the sea salty?

The answer to this question must begin with an explanation of where the water in the sea and ocean comes from. In rivers we find springs and springs - underground springs, but where does the water, and salty one, come from in the sea?

The reserves of both the Black Sea and the Atlantic Ocean are replenished with fresh water from rivers and precipitation in the form of snow or rain. Both consist of fresh water (in fact, also salty, just in a very small concentration). But unlike rivers, water from oceans and seas does not flow anywhere, but only evaporates when exposed to the sun’s rays. When evaporation occurs, the salts remain.

Another factor in the salinity of the sea is the movement of the rivers themselves flowing into it. On the way to the seas and oceans, river flows wash the salts that make up the stone out of the rocks and bring them with them to the sea, albeit in small quantities.

It turns out that the sea has become salty? Was it fresh before that? No, that's not true. The main reason, which modern scientists agree with, is the process of formation of the sea itself, which was just as salty millions of years ago. The fault for this is not the rivers, which did not exist then, but the volcanoes that covered our planet.

The water of the primary ocean was formed from volcanic gases, the composition of which is approximately the following: 75% of water accounts for 15% carbon dioxide and about 10% of various chemical compounds. These compounds include methane, ammonia, sulfur, chlorine and bromine, as well as various gases. So when the products of the eruption fell to the ground in the form of acid rain, they reacted with the bottom of the future sea, and as a result we got a salty solution.

How much salt is there in the sea?

About 35 are dissolved in one liter of sea water grams of salt.

How much water is there in the sea?

If we take the average depth of the world's oceans to be 3703 meters, and take the average surface area to be 361.3 million square kilometers, we get 1.338 billion km 3

Which seas are the freshest and saltiest?

Let's start with another record holder - the largest sea. The absolute champion in this category is the Sargasso Sea, which is located inside the Atlantic Ocean. Its area reaches 8.5 million square kilometers.

But the freshest sea is in Russia, and this sea is the Baltic. Compared to the waters of the Atlantic, its sunshine is 5 times lower. Why? About 250 rivers flow into the Baltic Sea, which “desalinize” the waters.

What about the saltiest sea?

The record holder for the percentage of salts is the Red Sea. Its salinity is about 41 grams per liter of water! This phenomenal content explains the unique properties of the sea: it is very easy to float in it, and being in it itself is quite beneficial for health.

Why is the Red Sea so salty? The point is the fumes, which we wrote about at the very beginning. Water evaporates from this sea at a tremendous speed due to high temperature and low humidity, so that rains simply do not have time to “desalinate” it, and besides, very little of it falls.

Question - competition

Using the data above, calculate how much TOTAL salt is dissolved in ALL the seawater on our planet?

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