All oceans are salty. Why is the sea salty? Why is the sea water salty

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

As folklore explains

Whose legend it is, 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 brother-rich. 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 it can grind whatever the soul desires. Naturally, the poor could not live quietly, in abundance, and not talk about his miracle find. In one version, he immediately rebuilt himself a palace on one day, in another - he threw a feast for the whole world. Since everyone around him knew that only yesterday he lived in poverty, those around him began to ask questions, where and why. The poor did not consider it necessary to conceal 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 to grind him money, gold, overseas delicacies, because having such a "device", it was already possible not to engage in the salt trade. He asked to grind salt for him so that he would not have to swim for her across the seas and oceans. The miracle millstone was launched, 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 for the fact

Rivers are the main source of salt 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 famous 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 together with small admixtures of salts into the depths of the sea. There is evaporation of water, but salts remain. Perhaps earlier, many hundreds of thousands of years ago, ocean waters were very 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

At a time when the earth's crust was in a stage of constant formation, there were frequent ejections 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 still taking place, because the seismological activity is even much lower than it was millions of years ago, but it is 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 through the movement of precipitation and winds. Moreover, in each open water body, the chemical composition of the main earth 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, and the benefits of taking baths, inhalation and the like. It's not for nothing that it's so popular sea ​​salt, which is even added to food instead of cooking.

The uniqueness of the 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 decided 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, and why they call it that.

Let's start with the fact that it is incorrect to call this body of water a sea. This is a lake, since it has no connection with the ocean. He 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 pond. But as a hospital, the Dead Sea is very, very popular.

Which sea is the most salty?

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

There are 41 grams of salt in a liter of water. Why is the Red Sea so salty? Firstly, its waters are replenished only due to 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 placement in the tropical zone. It would have been a little farther south, closer to the equator, and the amount of precipitation characteristic of this zone would have dramatically changed 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 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, the Black Sea can be distinguished, whose composition is also peculiar.

Its salt content is 17 ppm, and this is not entirely suitable for marine inhabitants. If the fauna of the Red Sea amazes 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 of salts, therefore 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 less salty than 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 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 rate, and this, in turn, affects the level and variety of living organisms in it, both flora and fauna. This is a huge system with a lot of parameters that ultimately make up an individual picture.

Children often ask different questions, which parents do not always find answers to. This situation is familiar to many. It would seem a trivial question: why is the water in the ocean salty, confuses adults, and not only them. Scientists' opinions on this issue are still different.

Of school curriculum we remember that all rivers flow into the seas and oceans, and, as you know, river water is fresh. But the rivers do not contain a large number of salt as well as rainwater, so why does the oceans stay so salty?

Several hypotheses were put forward, which are still relevant today!

1. At first, scientists believed that the rivers were not entirely fresh, because for many years they washed salts and minerals from the earth's rocks, carrying them into the sea and ocean waters. And the proof of this hypothesis is the Salt Lake and the Dead Sea, which are 10 times saltier than the oceans. But later, thanks to accurate calculations and analyzes, it was found that rivers could not saturate the oceans with such a large amount of salt.
2. Perhaps it all started with the primitive ocean, which consisted of a saturated solution of sulfur, methane, chlorine and carbon dioxide. Pure water accounts for only 75%. This data was obtained during the study of basaltic deposits and fossilized remains of various ancient sea creatures that are billions of years old. This was the initial composition of the super solution, in which the first life began to emerge, in the form of unicellular organisms.
3. Other hypotheses have been put forward in which volcanoes could affect the composition of the water of the ancient ocean. As a result of volcanic activity, a large amount of acid vapor was released into the atmosphere, which, condensing, spilled onto the ground in the form of acid rain. Over time, the activity of the volcanoes decreased, the atmosphere cleared, and there was less acid rain. Thus, the composition of the water in the oceans has returned to normal.
4. Not so long ago, hydrothermal vents were discovered at the bottom of the oceans. They are formed at the expense of sea ​​water which, seeping into terrestrial rocks, becomes much hotter and is thrown back, bringing with it a large amount of minerals.

It is worth noting that in different seas the percentage of salt is different, that is, each sea and ocean has its own individual composition. For example, the average salt content in seawater is 35g. per 1 liter, but in the Red Sea salinity reaches 41g. This is due to climatic features. The water in the Red Sea evaporates more intensively due to the high temperature and low humidity. But even in such conditions given quantity salt remains unchanged and holds a constant value.

Despite various studies, scientists have come to a single conclusion

The salinity of water in the oceans and seas remains at the same level, regardless of how much precipitation fell and how much fresh river water arrived. Why is this happening?

Most of the salts are spent on the formation of new mineral rocks, thereby normalizing the composition of the water. Salts participate in the formation of the embryos of marine life.

It is impossible to say which of these hypotheses is correct, because each has confirmation. Which one to believe is everyone's business. Many will prefer the hypothesis about ancient ocean, someone adheres to the hypothesis about volcanoes and precipitation, and everyone will be right in their own way.

Answering the question of your little "why", you can safely resort to any of the above explanation of the salinity of water in the seas and oceans.

I remember it was in the third grade, in a natural history lesson. The teacher told us that there are rivers on earth with fresh water, as well as seas and oceans with salt water. " Why is the ocean water salty?"- I asked and, oddly enough, Nadezhda Konstantinovna was confused. She just didn't know the answer to this seemingly simple child question... And then for the first time I realized that teachers do not know everything in the world.

Ocean As I got older, I tried to find an answer on my own using textbooks, an encyclopedia and the magazine "Around the World" (no one thought about the Internet at that time). And I realized that in vain she blamed the teacher for incompetence: it turns out that science still does not have an exact answer about the reasons for the salinity of ocean water.

Why ocean water is salty: hypotheses

Actually, the answer to the question, why ocean water tastes salty, is obvious: because there is a lot of salt in it. But with where it came from there in such quantities, I will try to figure it out. Here the main versions of the origin of salt in ocean water:

• volcanic;
• river;
• stone.

I'll tell you more about each of them.

Ocean water salty due to volcanoes

Millions of years ago when earth surface has not yet taken its current shape, nand our planet had many active volcanoes from which acidic substances were thrown into the ocean water. Entering into various reactions, these acids turned into salts that dissolved in the waters of the world's oceans.

The ocean water is salty because of the rivers that flow into it

“How so? - you ask - the water in the rivers is fresh, which means that it should dilute the ocean water, making it less salty! " Actually, river water cannot be considered absolutely fresh: it contains salts, but in small quantities. Rivers take their water from streams that flow from underground freshwater reservoirs. Fresh rainwater is added to them. But on the way to the sea, the river collects a small amount of salt from sand and stones that covered her bed. Flowing into the ocean, the river gives him this salt.

The water in the ocean is salty due to the blurring of stones.

In fact, this version explains rather not the origin of ocean salt, but the stability of its concentration. The seas and oceans have enough big line shores that are constantly washed by waves... The waves leave on coastal stones water particles which, evaporating, they turn into salt crystals... Gradually holes are formed in the stones and holes that become more and more salted... Over the years the stones collapse, and the salt returns to the ocean again.

For me personally, all these options for answering the question, n why ocean waters are salty, look controversial, but science has no others yet.

If you've ever surfed or swam, you're probably familiar with one of the strongest qualities of the ocean: its salinity. The oceans tend to contain more salt than most of the world's seas. On average, the concentration of salt in the ocean fluctuates around 35 grams per 1 liter of seawater with fluctuations from 3.4 to 3.6% (34-36 ‰). But if you won’t surprise anyone with the salinity of the ocean, then the question is why exactly it is so salty, m legs can be confused. Let's see why the sea water in the ocean is so salty?

If you removed all the salt from the oceans and spread it over the entire surface of the Earth, then it would form a layer about 150 meters thick. This is more than the height of the two Spassky Towers on Red Square in Moscow, stacked on top of each other. But how did such an amount of salt end up in the oceans?

You can thank the stones on the shore for that.

Rainwater contains a certain amount of dissolved carbon dioxide from the atmosphere... Slightly acidic rain destroys rocks on land, allowing dissolved minerals and ions, including chloride and sodium, to enter the ocean through hands and streams. It should be noted that for the most part, dissolved ions are responsible for the salinity of the ocean - they make 90% of their contribution to the salinity of the oceans.

It is noteworthy that rivers around the world also have salt, but the water in them usually does not taste salty like water in the ocean. This is because the ocean acts as a repository for all of these minerals. There their concentration is higher than in the sea. The rivers are playing important role in the transport of salts and other minerals to the ocean, and according to NOAA annually they dump into the ocean about 225 million tons of dissolved solids... But rivers aren't the only source of salt in the ocean.

Salt can also enter the oceans through hydrothermal vents. These holes release dissolved minerals into the sea. When sea water seeps into the rocks on seabed and closer to the core of the Earth, it starts to heat up. It then returns to the surface where it flows out of hydrothermal vents.

In areas of underwater volcanism, salt can also end up in the ocean. When fresh lava emerges from volcanoes on the seabed, it reacts with salty seawater, which dissolves some of the minerals in the lava.

But the ocean is not always equally salty. Some parts of the oceans are saltier than others. For example, the seabed of the Gulf of Mexico is filled with salt water, caused by the dissolution of ancient layers of salt in the seabed. These pools of super-salt sludge may even harbor strange bacteria at the bottom that scientists believe could be found elsewhere.

The phenomena of the world around us raise a lot of questions from the curious. For example, finding yourself on the shore of an endless reservoir, you begin to think: what kind of water in the ocean is fresh or salty? How can you explain the chemical composition of ocean water and can you drink it?

Since ancient times, the composition of the water in the seas and oceans has surprised people. In Germany, there are legends claiming that at the bottom of every sea there is a magic salt mill, and in Hungary - that this is all because of the tears of an unfortunate girl grieving under the water column.

Finding out whether the water in the ocean is salty is actually as easy as shelling pears - just refer to the materials modern research... Indeed, sea and ocean water is very salty, and sometimes the concentration of salts is excessively high: one glass of the "drink" from the Dead Sea is enough to not regain consciousness at all.

The saltiest water areas in the world are:

• Atlantic Ocean: southern part (salt concentration is 37.9 ppm) and Northern part (37,6);
• Pacific Ocean: southern part (36, 9) and northern part (35.9);
• Entire Indian Ocean (36.4 ppm).

Why is the water in the ocean salty?

Oddly enough, but to such a simple question - why is the water in the ocean salty - even modern scientists have not found an unambiguous answer. Some researchers believe that this is due to volcanic activity, while others believe that salt enters the oceans through rivers and seas.

About the amount of salt and fresh water on earth.

Two theories

The first group of scientists claims that a very long time ago, when the earth's crust was just forming, volcanoes on Earth were extremely active. Their eruptions led to the emergence of acid rain - but the oceans itself consisted of acids. As a result, various complex substances"Collided" with each other, and as a result of the reaction, the oceanic waters became safe for life, which still had to originate. But only very salty.

As for the "earth" theory, it says that salts are found in all bodies of water in the world. And this is really so - fresh water is not devoid of salts, there are just very few of them. Flowing into the oceans, rivers and seas bring with them salts washed out of the soil. They, in turn, remain in place - where else can they go? Yes, in the course of the natural cycle, water also evaporates from the surface of the oceans, but the salts are too heavy to follow.

As you can see for yourself, these theories are quite logical. Or maybe both groups of researchers are right at once, and at first the salts arose thanks to volcanoes, and numerous currents brought them even more?

Can a fresh ocean arise

What determines the salinity of water in the ocean? Many factors play a role here, including underwater currents, the presence of glaciers, the intensity of their melting, the activity of evaporation, etc. In addition, in the depths, under the very bottom of the ocean, there are deposits of the purest fresh water.

But even if we imagine that a crystal clear water space will appear on Earth, it is obvious that fresh water in the ocean would not stay long. After all, the fact that rivers constantly add salt washed out of the soil to the ocean waters is beyond doubt - scientists are skeptical only that this could cause the emergence of vast salt reservoirs as such.

Is it possible to drink sea water

So, we figured out why the water in the seas and oceans is salty, and found out that drinking it is not recommended. But how does such a limitation exist?

In fact, ocean water is contraindicated for humans due to the structural features of the body. The kidneys are responsible for the elimination of salts and other "heavy" substances from food, which may simply not be able to cope with the excess load. And a liter of sea water contains more than 30 grams of salt! That is why the unfortunate, shipwrecked and able to escape in boats, often die of thirst in the middle of water.

Why is the sea salty: Video