At school, they ask quite a lot of interesting questions. Some of them at first glance seem quite simple and it is easy to answer them, although in fact everything is far from being so simple. Tell me, do you know why the water in the sea is salty? We strongly doubt this, since even scientists do not know the exact answer!
Versions and hypotheses
Let's start, perhaps, with this - when did the water bodies on Earth become salty? It probably happened a very long time ago. But when exactly? Some historians claim that this happened millions of years ago, even before the dinosaurs died out. Others are sure that some time ago the seas consisted exclusively of fresh water ... Now you can’t tell who is right and who is not.
- But back to our main question. If you believe the school course, then the reservoirs became salty thanks to the rivers. But how is it, you ask, because the water in the rivers is fresh! We will agree with you, but we will add that it also contains dissolved salts, however, in microscopic quantities. However, they are there, although we do not taste them. Based on this, it turns out that the rivers not only desalinate the seas, but also salt them. After the river water enters the sea, its nth part evaporates under the influence of the natural environment, but the salts do not go anywhere and remain in the sea. Scientists have even found out that it is thanks to the rivers that the World Ocean receives almost three million tons of various substances and elements. Huge number! And imagine that such a cycle in nature has been going on for far more than one million years? Then it is clear why the water in some reservoirs is so salty ...
It would seem that the answer has been found. But wait! Other experts who support other theories say that almost all the salts that fall into the sea precipitate and over time huge stone layers and rocks begin to form from them. In addition, river and sea water contain very different substances and elements. So, in the first one there is negligibly little table salt, but there are a lot of carbonates, lime and soda, and the second is known for a large amount of table salt and sodium. In general, not everything is so obvious.
- The second theory on this issue is also very interesting. Those experts who support it claim that over the past several billion years that our planet has existed, the rivers have always been fresh, and the seas have been salty. Theoretically, in this case, river water could become salty, but the laws of nature intervene here - the seas and oceans cannot flow into rivers, this happens exactly the opposite even in our time.
- According to the third version, animals played a significant role. So, one of the scientists claims that once river water practically did not differ from sea water. It was used for drinking by many animals. If you have not forgotten, it contains a large amount of calcium, which is so necessary for the development of the skeleton of living beings. So, the animals gradually fished out all the elements they needed from the rivers, among which were salts. This happened over hundreds of millions of years, as a result of which the rivers practically got rid of sodium chloride. Of course, this theory has the right to life, although it sounds very far-fetched. Why? It's simple - the reserves of sea salt are simply huge. So, if it is evenly distributed over land, then it will cover our entire planet with a layer more than a hundred meters thick! Can you imagine that fish and animals could eat so much mineral, albeit for a huge period of time? We doubt it.
- This theory is supported by many experts. They say volcanoes are to blame. When the earth's crust was just beginning to form, there was tremendous volcanic activity on Earth. The gases from the volcanoes contained vapors of fluorine, bromine and chlorine, so acid rains periodically occurred. It was they who formed the seas, which, of course, were also acidic. However, this water entered into a chemical reaction with solid rocks, extracting from them such alkaline elements as sodium, potassium, magnesium and calcium. This is how salts were formed, which neutralized the acidity of the water, gradually making it salty. The composition of water finally stabilized about 500 million years ago.
Outcome
And there is no result as such, because neither we nor scientists know the answer to the question posed. But we still hope that someday a specialist will solve this riddle of nature.
Sea water has a not very pleasant salty taste with bitterness, which makes it impossible to drink it. But not every sea has the same salinity. Having visited the beach for the first time, the child often asks the question - why is the water salty? The question is simple, but it puzzles parents. So, why is the water in the seas and oceans salty, what determines the salinity of the water.
The impact of the location of the seas and oceans
If we take the seas of the planet, then the water in each of them will differ in its composition. Experts say that closer to the northern regions, the salinity index increases. To the south, the percentage of salt in sea water decreases. But one feature should be remembered here - ocean water is always much saltier than sea water, the location does not affect this. And this fact is no longer explained.
The salinity of water is due to the content of sodium and magnesium chlorides in it, as well as other salts. Alternatively, certain areas of the land are enriched with deposits of these components, thereby differing from other regions. Frankly, such an explanation is rather far-fetched, if we take into account the sea currents, because the level of salt content over time should stabilize throughout the volume.
Causes affecting the salt content in water
Scientists offer several explanations for the water in the seas and oceans being salty. Some think that the high salt content is possible due to the evaporation of the waters of the rivers flowing into the seas. Others argue that salinity is nothing more than the result of water washing away rocks and rocky areas. There are those who compare this phenomenon with the result of the action of volcanoes.
Many are skeptical about the opinion that salts enter the seas with the waters of rivers. But no one denies that river water still contains salt, though not in such quantities as in the ocean.
Consequently, a certain desalination occurs from the ingress of river water into the sea, 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, carried further by sea currents and giving bitterness to the water.
Volcanoes also have their effect. When emitted, they carry a decent amount of various components, including salts. Volcanic activity was especially high during the formation of the Earth. Large emissions of acids were produced into the atmosphere. There is an assumption that from the effects of acid rain, the water in the seas was originally 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 in water. This reason is associated with winds capable of bringing salts, with soil composition capable of passing moisture through itself, saturating it with salts, salt-releasing minerals under the ocean floor.
Where is the most salt found?
Liquid in the form of sea water is the largest amount on the planet. For this reason, many seek to relax on the sea beaches, going on vacation. Surprisingly, the mineral composition of the liquids of different seas differs from each other. And there are reasons for this. So, which sea is the most salty?
The answer to this question is provided by research statistics. The most salty sea is rightfully the Red 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, somewhat behind the Red Sea. Ocean waters differ in the level of salt content equal to thirty-four grams.
What is the secret of the leadership of the Red Sea? Over its surface, on average, about a hundred millimeters of precipitation falls annually. This is a small amount, despite the fact that evaporation per year reaches up to two thousand millimeters.
There is no inflow of water into the Red Sea from the flowing rivers due to the lack of such, replenishment occurs solely due to precipitation and water resources of the Gulf of Aden, where the ox is also brackish.
Another reason is water mixing. In the winter and summer seasons, the fluid layers change. Only the upper layers of water are subjected to evaporation. The rest of the salts sink to the bottom. For this reason, their number per liter of water is constantly growing.
Sometimes, the Dead Sea is called the most salty, in which the salt percentage per unit of water reaches more than three hundred grams. This level even affects the fact that fish do not 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.
Here's a mystery - why is the sea water salty, but not in rivers and lakes? There is currently no single correct answer to this question, and there are active disputes and discussions on this subject in the scientific world.
Scientists only distinguish two main theories, each of which seems to be true, but at the same time they contradict each other, and there are several strong arguments against each.
First theory. The seas and oceans acquired salinity as a result of slow and gradual processes.
So, according to this theory, sea water became salty as a result of the water cycle in nature. This process can be described in more detail as follows: the rain gradually washed out and dissolved the mineral salts contained in rocks and soils, rainwater fell into the rivers. Rivers also wash out particles of various salts from the bottom, then this one fell into the seas and oceans under the influence of the current. Under the influence of solar heat, water over the seas evaporated and again fell to the ground in the form of rain and other precipitation - the process was repeated. And salt, of course, accumulated in the oceans for millions of years, gradually increasing the level of salinity. But here the big question arises: Why, for more than 500 million years, the salinity level of ocean water has not increased and kept at the same level of 35 ppm (35 grams of salt per 1 liter of water), while rivers have not stopped supplying mineral elements all this time?
Second theory. Ocean water was salty from the beginning.
At the initial stages of the formation of our planet, volcanic smoke was emitted from the depths of the mantle along with the first water vapor into the atmosphere. These smokes were enriched with volcanic waste products - chlorine, phosphorus and bromine. Water mixed with these vapors, more like acid than water. The primary acidic water filled the future oceans and seas and destroyed the crystalline rocks of the earth's crust at the bottom, as a result, elements such as potassium, calcium, magnesium, sodium were released ... Then a simple chemical reaction took place, in which chlorine interacted with sodium, and, in fact, salt was produced. Over time, the activity of volcanoes decreased and the level of salinity of the water stabilized.
Both theories do not give an exact answer, but only suggest a possible course of events and processes. The true reason for this interesting question is yet to be discovered.
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 ejections of magma with an incredible amount of 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 the mineral composition is unique in each reservoir. 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. Its average temperature is 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.
Why is the sea water salty, and in rivers and lakes fresh? Today there are two versions of the answer to this question, traditional and more modern.
Why is the water in the sea salty, the traditional hypothesis
Traditionally it was thought that salty sea water, because rivers bring salt to the sea, washing it out of the rocks along which their channel passes. In river water, it turns out, there is also salt, only it is 70 times less than in sea water. Every year, rivers add one sixteen millionth of the salt of its total volume to the World Ocean.
Sea water is constantly evaporating (and the salts remain in the sea!), Then it returns again in the form of precipitation to the land, enters the rivers, is again enriched with the salt of the rocks, which the rivers carry into the sea. It is not surprising that over millions of years of such a water cycle in nature, the World Ocean has pretty much “salted out”. This answer to the question, , also explains the large amount of salt in lakes that do not have a runoff. But he does not explain why the salts in sea and river water have different chemical compositions (and they do!). Therefore, another, more modern hypothesis arose,.
Why the water in the sea is salty, a more modern hypothesis
According to this hypothesis, sea water was originally salty, since the primary ocean on Earth is a condensate of gases from volcanic eruptions. The composition of these gases includes water and many chemical elements, among them the so-called "sour fumes", consisting of chlorine, fluorine, bromine and inert gases. Pouring acid rain on the surface of the Earth, the products of volcanic eruptions entered into a chemical reaction with solid rocks, as a result of which a saline solution was formed.
At present, scientists have agreed that both of these hypotheses have the right to exist and complement each other.
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