Water is one of the strongest solvents. It is able to dissolve and destroy any rock on the surface of the earth. Water streams, streams and drops gradually destroy granite and stones, while leaching of easily soluble components from them occurs. No strong rock can withstand the destructive effects of water. This is a long but inevitable process. Salts that leach out rocks, give sea water a bitter-salty taste.

But why is the water in the sea salty, and fresh in the rivers?

There are two hypotheses for this.

Hypothesis one

All impurities dissolved in water are carried by streams and rivers to the seas and oceans. River water is also salty, only salts in it are 70 times less than in sea water. Water from the oceans evaporates and returns to the earth in the form of precipitation, while dissolved salts remain in the seas and oceans. The process of "delivery" of salts to the seas by rivers has been going on for more than 2 billion years - a time sufficient to "salt" the entire World Ocean.

Sea water contains almost all the elements that exist in nature. It contains magnesium, calcium, sulfur, bromine, iodine, fluorine, copper, nickel, tin, uranium, cobalt, silver and gold are contained in small amounts. Chemists have found about 60 elements in sea water. But most of all, sea water contains sodium chloride, or table salt, which is why it is salty.

This hypothesis is supported by the fact that lakes that do not have a runoff are also salty.

Thus, it turns out that initially the water in the oceans was less salty than it is now.

But this hypothesis does not explain the differences in the chemical composition of sea and river water: chlorides (salts of hydrochloric acid), and in rivers - carbonates (salts of carbonic acid).

Hypothesis two

According to this hypothesis, the water in the ocean was originally salty, and the reason for this was not rivers at all, but volcanoes. Proponents of the second hypothesis believe that during the formation of the earth's crust, when volcanic activity was very high, volcanic gases containing chlorine, bromine and fluorine vapors poured acid rain. Thus, the first seas on Earth were... acidic. Entering into chemical reaction with solid rocks (basalt, granite), the acidic water of the oceans extracted alkaline elements from rocks - magnesium, potassium, calcium, sodium. Salts were formed that neutralized sea water - it became less acidic.

As volcanic activity decreased, the atmosphere was cleared of volcanic gases. The composition of ocean water stabilized about 500 million years ago - it became salty.

But where do carbonates disappear from river water when they enter the World Ocean? They are used by living organisms - to build shells, skeletons, etc. But chlorides, which prevail in sea water, they avoid.

At present, scientists have agreed that both of these hypotheses have the right to exist, and do not refute, but complement each other.

Often, the sailors of ships that were wrecked or lost in sea waters died of thirst. But few people know why this is so, because there is a lot of water around.

The thing is that sea water is saturated with such a composition that it is not suitable for human body and does not quench your thirst. In addition, sea water has a specific taste, bitter-salty and is not suitable for drinking. This is all because of the salts dissolved in it. Let's see how they got there.

What makes water taste salty

Salt is crystalline. Ocean waters contain almost all the elements of the periodic table. Hydrogen and oxygen combine to form water molecules. It also contains impurities of fluorine, iodine, calcium, sulfur and bromine. The mineral base of sea water is dominated by chlorine and sodium (ordinary salt). This is why the water in the sea is salty. It remains to be seen how the salts get into this water.

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How sea water was formed

Scientists have been conducting experiments for a long time and trying to find out why sea water is salty and river water is fresh. There are several theories for the formation of salty sea water.

It turns out that the water in rivers and lakes is also salty. But the salt content in them is so small that it is almost imperceptible. According to the first theory, river waters, getting into the seas and oceans evaporate, and salts and minerals remain. Because of this, their concentration increases all the time and the water in the sea and ocean becomes salty.

According to scientists, the process of salinization of the seas takes place over a billion years. But contrary to the first theory, it has been proven that the waters in the oceans do not change their chemical composition for a long time already. And those elements that come with river water only support the oceanic composition, but do not change it in any way. This leads to another theory. Salt has a crystalline consistency. Waves crashing against the shore wash the rocks. They form holes. When the water evaporates, salt crystals remain in these wells. When the rock breaks, the salt gets back into the water and it becomes salty.

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Consequence of volcanic activity

Scientists have concluded that the water in the seas was salty even in those days when mankind did not exist on the planet. And the reason for this was volcanoes. The earth's crust has been formed by magma ejection over the years. And the composition of volcanic gases contains chemical combinations of chlorine, fluorine and bromine. They fell into the ocean waters in the form of acid rain and initially the water in the ocean was acidic. This water broke apart the crystalline rocks of the earth's crust, and extracted magnesium, potassium and calcium. These acids began to form salts as a result of the reaction with solid earthen rocks. Few people know that the salt familiar to us was formed as a result of the reaction of perchloric acid from the ocean and sodium ions from volcanic rocks.

Everyone who was on the beach could make sure that the water in the sea tasted salty. But where does salt come from if fresh water enters the ocean through rains, rivers and? Why the sea is salty and has it always been so - time to figure it out!

How is the salinity of water determined?

Salinity refers to the content of salts in water. Salinity is most commonly measured in ppm » (‰). A ppm is one thousandth of a number. Let's give an example: the salinity of water is 27 ‰, which means that one liter of water (that's about 1000 grams) contains 27 grams of salt.

Fresh water is considered to be water with an average salinity of 0.146 ‰.

Medium the salinity of the oceans is 35 ‰. Sodium chloride, also known as table salt, makes the water directly salty. Among other salts, its share in sea water is the highest.

The most salty sea is the Red Sea. Its salinity is 41‰.

Where does the salt in the seas and oceans come from

Scientists still disagree about whether sea water was originally salty or acquired such properties over time. Depending on the versions, different sources of the appearance of salts in the World Ocean are also considered.

Rains and rivers

Fresh water always has a large number of salts, and rainwater is no exception. It always contains traces of substances dissolved in it, which were captured during the passage through the atmosphere. Getting into the soil, rainwater washes away a small amount of salts and eventually brings them to lakes and seas. From the surface of the latter, water evaporates intensively, falls again in the form of rain and brings new minerals from the land. The sea is salty because all the salts remain in it.

The same principle applies to rivers. Each of them is not completely fresh, but contains a small amount of salts captured on land.

Confirmation of the theory - salt lakes

Evidence that salt comes through rivers are the most saline lakes: the Great Salt Lake and the Dead Sea. Both are about 10 times saltier than sea water. Why are these lakes salty?, while most of the world's lakes are not?

Usually lakes are temporary storages for water. Rivers and streams bring water to lakes, and other rivers carry it away from these lakes. That is, water enters from one end, and leaves from the other.

The Great Salt Lake, the Dead Sea and other salt lakes have no outlets. All the water that flows into these lakes leaves only by evaporation. When the water evaporates, the dissolved salts remain in the water bodies. Thus, some lakes are salty because:

• rivers carried salt to them;
• the water in the lakes evaporated;
• salt remained.

Over the years, the salt in the lake water has accumulated to its current level.

Interesting fact: The density of salt water in the Dead Sea is so high that it practically pushes a person out, preventing him from sinking.

The same process made the seas salty. Rivers carry dissolved salts to the ocean. Water evaporates from the oceans to fall again as rain and replenish rivers, but the salts remain in the ocean.

hydrothermal processes

Rivers and rains are not the only source of dissolved salts. Not so long ago, on the ocean floor were discovered hydrothermal vents. They represent places where sea water has seeped into the rocks of the earth's crust, has become hotter and is now flowing back into the ocean. Along with it comes a large amount of dissolved minerals.

underwater volcanism

Another source of salts in the oceans is underwater volcanism - volcanic eruptions underwater. It is similar to the previous process in that sea water reacts with hot volcanic products and dissolves some mineral components.

Have you ever thought about what you would do if you were on desert island in the open ocean? You would first like to find food, make fire, make shelter, and find water. Water? That's right, and although you may be surrounded by an endless ocean, those of you who have been to the sea beach know that sea water is not suitable for drinking.

Why not? Because . But why is sea water salty and not drinkable?

Ocean water is salty because it contains a large amount of dissolved minerals. These minerals are often referred to as "salts". Depending on where you are in the world, sea water contains approximately 3.5% salts. The water near has a high salinity, while the northern waters contain less salts.

At the bottom there is a huge amount of minerals that are destroyed and rise to the surface by the natural currents of the ocean. As the movement of water and waves breaks the ocean floor, minerals dissolve into the water and salts increase. So the ocean constantly replenishes its salinity.

The oceans and seas also get some of their salt from streams, rivers and lakes. While this may seem counterintuitive since these bodies of water contain fresh water, you may be surprised to learn that all lakes, rivers, and streams contain some amount of dissolved salts. However, the concentration of salts in these bodies of water is much less than in the oceans, so their water seems to be less salty than ocean water.

Salts cannot accumulate in most lakes because they have outlets such as rivers and streams. These outlets allow water to flow to the oceans, carrying minerals with it.

On the other hand, it is an example of a body of water without an outlet. Minerals that drain into the Dead Sea cannot be released into the open ocean because there is no runoff. As a result, the Dead Sea contains some of the saltiest waters on earth.

In fact, up to 35% of the salts are found in the waters of the Dead Sea! This is almost ten times more than the concentration of salt in the oceans. The salty water of the Dead Sea is deadly to most living creatures, so you won't find fish or sea creatures there. Only a few types of bacteria and algae can survive in the harsh conditions of the Dead Sea. That's why it's called Dead!

Although you certainly don't want to drink water from this sea, you can swim in it. Due to the high concentration of salt, the density of water in the Dead Sea is much greater than in fresh water. This allows the swimmer to keep well on the surface of the water. Diving into the Dead Sea is a bit like dropping a plastic lid into a bowl of water. The dense water makes it easy to swim, even without much effort. In fact, the water makes swimmers so buoyant that it is very difficult for them to reach the bottom or swim underwater.

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 is this, and who exactly invented 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, the tale conveys 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 goes for alms to the stingy rich brother. Having received a half-dried ham as a “gift”, the poor, 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 everything that the soul pleases. Naturally, the poor man could not live quietly, in abundance, and not talk about his miracle find. In one version, he immediately built a palace for himself one day, in another, he threw a feast for the whole world. Since everyone around him knew that just yesterday he lived in poverty, 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 such person was a salt merchant. Having stolen the millstone, he did not ask him to grind money, gold, overseas delicacies, because having such a “device”, one could no longer engage in the salt trade. He asked to grind salt for him so that he would not have to swim behind her across the seas and oceans. A miracle millstone started up, and it ground so much salt for it that it sank the ship of the unfortunate merchant, 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

Rivers are the main source of salts in the seas and oceans.

Yes, those rivers that are considered fresh (more correctly, less salty, because only 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 a huge amount of water, along with small impurities of salts, into the depths of the sea. There, water evaporates, but salts remain. Perhaps earlier, many hundreds of thousands of years ago, the ocean waters were very different. But they add another factor that can explain why the seas and oceans are salty - volcanic eruptions.

Chemicals from volcanoes that bring salt to the sea

At a time when the earth's crust was in a state of constant formation, there were frequent eruptions of magma with an incredible amount various elements to the surface - both on land and under water. Gases, indispensable companions of eruptions, mixing with moisture, turned into acids. And those, in turn, reacted with the alkali of the soil, forming salts.

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

In principle, the rest of the facts explaining why the water in the sea is salty have already been studied: salts enter the seas from the soil by means of movement by precipitation and winds. Moreover, in each open reservoir, the chemical composition of the main terrestrial liquid is individual. When asked 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 the benefits when taking baths, inhaling and the like. No wonder sea salt is so popular, which is even added to food instead of table salt.

The uniqueness of the mineral composition

We have already mentioned that mineral composition unique in every body of water. Why the sea is salty and how much it is, decides the intensity of evaporation, that is, the temperature of the wind on the reservoir, the number of rivers that flow into the reservoir, the richness of flora and fauna. So, everyone knows what the Dead Sea is, 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. They called him dead because of the huge proportion of salts - 340 grams per liter of water. For this reason, no fish is able to survive in the reservoir. But as a hospital, the Dead Sea is very, very popular.

Which sea is still the most salty?

But the right to be called the most salty 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 is also salty. Secondly, the evaporation of water here is twenty times higher than its replenishment, which is facilitated by the location in the tropical zone. If it were a little further south, closer to the equator, and the amount of precipitation typical for this zone would drastically change its content. Due to its location (and the Red Sea is located between Africa and the Arabian Peninsula), it is also the warmest sea among all available on planet Earth. His average temperature- 34 degrees Celsius. The whole system of possible climatic and geographical factors has 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 peculiar.

Its salt content is 17 ppm, and these are not quite suitable indicators for marine inhabitants. If the fauna of the Red Sea strikes any visitor with its variety of colors and forms of life, then do not expect this from the Black Sea. Most of the "settlers" of the seas do not tolerate water with less than 20 ppm salts, therefore the diversity of life is somewhat reduced. But it contains many useful substances that contribute to the active development of unicellular 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 area of ​​​​the sea itself by five times. At the same time, the Black Sea is very closed - only a thin strait connects it with the Mediterranean, but otherwise it is surrounded by land. 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 sea water salty? It depends on many factors - river waters and their saturation with substances, winds, volcanoes, precipitation, evaporation intensity, and this, in turn, affects the level and diversity of living organisms in it, both flora and fauna. This is a huge system with a large number of parameters that ultimately make up an individual picture.