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, inhalations, 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 sea 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.
Why is the water in the ocean salty and the water in rivers fresh? The answer to this question is ambiguous. There are different points of view that reveal the essence of the problem. According to scientists, it all comes down to the ability of water to destroy rock and leach easily soluble components from it, which end up in the ocean. This process occurs continuously. Salts saturate sea water, giving it a bitter-salty taste.
Everything seems to be clear, but at the same time, there are two diametrically opposed opinions on this issue. The first comes down to the fact that all the salts dissolved in the water are carried by rivers into the ocean, saturating the sea water. There are 70 times less salts in river water, so it is impossible to determine their presence in it without special tests. It seems to us that the river water is fresh. In fact, this is not entirely true. Seawater is constantly saturated with salts. This is also facilitated by the process of evaporation, as a result of which the amount of salts constantly increases. This process is endless and lasts about two billion years. This is enough time to make the water salty.
The composition of sea water is quite complex. It contains almost the entire periodic table. But most of all, it contains sodium chloride, which makes it salty. By the way, in closed lakes the water is also salty, which confirms the correctness of this hypothesis.
Everything seems to be correct, but there is one thing! Sea water contains salts of hydrochloric acid, and river water contains carbonic acid. That is why scientists have put forward an alternative hypothesis. They believe that sea water was initially salty, and the rivers have absolutely nothing to do with it. This is all due to volcanic activity, the peak of which occurred at the time of the formation of the earth’s crust. Volcanoes released huge amounts of steam saturated with acids into the atmosphere, which condensed and fell to the ground in the form of acid rain. The sediments saturated the seawater with acid, which reacted with the hard basaltic rocks. As a result, huge amounts of alkali were released, including sodium, potassium and calcium. The resulting salt neutralized the acid in seawater.
Over time volcanic activity decreased, the atmosphere was cleared of vapors, and less and less acid rain fell. About 500 million years ago, the composition of sea water stabilized and became what we know it today. But the carbonates that enter the ocean with river water serve as an ideal building material for marine organisms. They build coral islands, shells, and their skeletons from it.
Which hypothesis to choose is a purely personal matter. In our opinion, they both have a right to exist.
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? How can we explain the chemical composition of 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 look at the materials of modern research. Indeed, sea and ocean water is very salty, and sometimes the concentration of salts is excessively high: one glass of “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 the earth’s crust was just being 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, various complex substances “collided” with each other, and as a result of the reaction, 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 indeed it is - 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, no one doubts that rivers constantly add salts washed out of the soil into ocean waters - 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 a liter of 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
Often, 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 the human body and does not quench thirst. In addition, sea water has a specific taste, bitter and salty, and is not suitable for drinking. This is all due to the salts dissolved in it. Let's figure out how they got there.
What gives water its salty taste?
Salt has a crystalline appearance. Ocean waters contain almost all 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 figure out why sea water is salty and river water is fresh. There are several theories about the formation of salty sea water.
It turns out that rivers and lakes also have salty water. But the salt content in them is so small that it is almost unnoticeable. According to the first theory, river waters entering the seas and oceans evaporate, but 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 has been going on for a billion years. But contrary to the first theory, it has been proven that the waters in the world's oceans have not changed their chemical composition for a long time. And those elements that come with river water only maintain the oceanic composition, but do not change it in any way. This leads to another theory. Salt has a crystalline consistency. Waves hitting the shore wash the stones. Lures form in them. When the water evaporates, salt crystals remain in these holes. When the rock breaks down, the salt gets back into the water and it becomes salty.
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The warmest seas in the world
Consequence of volcanic activity
Scientists have concluded that the water in the seas was salty back in the days when humanity did not exist on the planet. And the reason for this was volcanoes. The earth's crust was formed over many years by the emission of magma. And volcanic gases contain chemical combinations of chlorine, fluorine and bromine. They entered the ocean waters in the form of acid rain, and initially the water in the ocean was acidic. This water broke up the crystalline rocks of the earth's crust, and extracted magnesium, potassium and calcium. These acids began to form salts as a result of reaction with hard earth rocks. Few people know that the salt we are used to is formed as a result of the reaction of perchloric acid from the ocean and sodium ions from volcanic rocks.
Anyone who was on the beach could see that the water in the sea tasted salty. But where does 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 share 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 a large number of salts, and rainwater is no exception. It always contains traces of dissolved substances that were captured during its passage through the atmosphere. Getting into the soil, rainwater washes away a small amount 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 most saline lakes: Bolshoye 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 rocks of 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.
