Why is the sea salty? Why are the seas and oceans salty? Ocean water: fresh or salty? Why is the ocean salty?

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

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

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 very salty, and sometimes the concentration of salts is excessively high: one glass of the “drink” from the Dead Sea is enough to prevent you from regaining consciousness at all.

The saltiest bodies of water 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 (35.9);
• Entire Indian Ocean (36.4 ppm).

Why is the ocean water salty?

Oddly enough, even modern scientists have not found a clear answer to such a simple question - why is the water in the ocean salty? Some researchers believe that this is due to volcanic activity, while others believe that salt comes into 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 earth's crust just formed, volcanoes on Earth were extremely active. Their eruptions led to the occurrence of acid rain - but the World Ocean itself consisted of acids. As a result, different complex substances“collided” with each other, and as a result of the reaction, the ocean waters became safe for life, which had yet to arise. But only very salty ones.

As for the “earth” theory, it says that salts are contained in all reservoirs of the world. And this is true - 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 - and where else can they go? Yes, during the natural cycle, water evaporates from the surface of the oceans, but the salts are too heavy to follow it.

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

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 body of water will appear on Earth, it is obvious that fresh water in the ocean would not linger for long. After all, what rivers constantly add to ocean waters salts washed out of the soil, no one doubts - scientists are skeptical only that this could cause the appearance of vast salty 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 why does this limitation exist?

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

Why is the sea salty: Video

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

How is water salinity determined?

Salinity refers to the salt content in water. Most often, salinity is measured in " ppm » (‰). Permille is one thousandth of a number. Let's give an example: a water salinity of 27 ‰ will mean that one liter of water (this is approximately 1000 grams) contains 27 grams of salt.

Water with an average salinity of 0.146 ‰ is considered fresh.

Average The salinity of the World Ocean is 35 ‰. What makes water salty is sodium chloride, also known as table salt. Among other salts, its proportion in sea water is the highest.

The saltiest sea is the Red Sea. Its salinity is 41‰.

Where does salt come from in the seas and oceans?

Scientists still disagree about whether seawater 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 considered.

Rains and rivers

Fresh water always has no large number salts, and rainwater is no exception. It always contains traces of dissolved substances that were captured during its passage through the atmosphere. When rainwater gets into the soil, it washes away small amounts of salts and eventually carries them to lakes and seas. From the surface of the latter, water intensively evaporates, 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 small amounts of salts captured on land.

Confirmation of the theory - salt lakes

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

Lakes are usually temporary storage areas for water. Rivers and streams bring water to lakes, and other rivers carry it away from these lakes. That is, water comes in 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 through evaporation. When water evaporates, dissolved salts remain in bodies of water. Thus, some lakes are salty because:

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

Over many years, 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 rain are not the only source of dissolved salts. Not long ago, they were discovered on the ocean floor hydrothermal vents. They represent places where seawater has seeped into the earth's crust, become hotter, and is now flowing back into the ocean. Along with it comes a large amount of dissolved minerals.

Submarine volcanism

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

Have you ever thought about what you would do if you were on desert island in the open ocean? You would first want 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 a sea beach know that sea water is not suitable for drinking.

Why not? Because . But why is sea water salty and not suitable for drinking?

Ocean water is salty because it contains large amounts of dissolved minerals. These minerals are often called "salts". Depending on where in the world you are, seawater contains approximately 3.5% salts. The water around it has 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 natural ocean currents. As the movement of water and waves erodes the ocean floor, minerals dissolve in the water and the amount of salts increases. This is how the ocean constantly replenishes its salinity.

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 lower than in the oceans, so their water appears 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 the flow.

On the other hand, it is an example of a reservoir without an outlet. Minerals that flow into the Dead Sea cannot be released into the open ocean because there is no runoff. Because of this, the Dead Sea contains some of the saltiest water 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. Salty water of the Dead The sea is lethal to most living things, so you won't find any fish or sea creatures there. Only a few species of bacteria and algae can survive the harsh conditions of the Dead Sea. That's why it's called Dead!

While you certainly wouldn't want to drink the 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 stay 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, 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 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 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

At a time when the earth's crust was in a state of constant formation, there were frequent emissions of magma with an incredible amount 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 mineral composition 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.

Ocean! This word sounds loud and menacing. This is one of a kind huge accumulation of water surrounding continents and islands. This is the boundless sea that washes the universe. But, I wonder what kind of water is in the ocean, what is its chemical composition?

Chemical composition of ocean water

Ordinary residents often deal with fresh water, which contains almost no foreign impurities. However, it also contains dissolved salts, although in small concentrations. What then can we say about the ocean? What is the water like in the ocean? Judging by its composition, the ocean can hardly be called water. It is very similar to strong salty brine. Each kilogram of it contains about 35 grams of various salts. Scientists have found that dissolved in the ocean chemical compounds all elements.

Salt in the ocean

The fact that there is salt water in the ocean is an undeniable fact. But in different parts The world's oceans have different salt concentrations. The Atlantic Ocean is considered the saltiest of all oceans, although some scientists consider the Indian Ocean to be the saltiest. And the least salty water is Gulf of Finland. Despite the fact that salinity differs in different parts of the World Ocean, the ratio of different salts in water is the same. This amazing constancy is explained by the mixing of water by waves and currents.

Is there an ocean with fresh water

Fresh water in the ocean? This is impossible! Although there are hypotheses in science, they are just assumptions. This freshening is explained by the influence of powerful rivers flowing into the ocean and heavy precipitation in temperate latitudes. However, rivers that tend to the ocean do not contain pure fresh water. Rivers wash away rocks and, washing away salts, carry them into the ocean. And let's not forget about the water cycle. After evaporation, ocean water falls as rain or snow, collects in rivers and returns to the ocean. Thus, salinization of the ocean continues to this day.