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 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 originally salty, and rivers have nothing to do with it. This is all due to volcanic activity, the peak of which occurred at the time of 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 sea water.
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.
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 the 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 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 chemical compounds of all elements are dissolved in the ocean.
Salt in the ocean
The fact that there is salt water in the ocean is an undeniable fact. But in different parts of the World Ocean, the concentration of salt is different. The Atlantic is considered the saltiest of all oceans, although some scientists consider the Indian Ocean to be the saltiest. And the least salty is the water of the 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 desalination is explained by the influence of powerful rivers flowing into the ocean and heavy precipitation in temperate latitudes. However, the rivers that flow towards 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.
Water covers a large area of our planet. The vast majority of this water is part of the seas and oceans, so it is salty and tastes bad. According to the server "Ocean Service" 3.5% of the oceans are made up of sodium chloride or table salt. This is tons of salt. But where does it come from and, therefore, why is the sea salty?
It is important to know!
For 4 billion years, rain waters the earth, rainwater penetrates into the rocks, from where it finds its way into. It carries dissolved salt with it. Over the course of geological history, the salt content of the sea gradually increases. The Baltic Sea, due to low water temperatures, contains 8 times less salt than, for example, the Persian Gulf. If the water from all the oceans evaporated today, the remaining salt would form a coherent layer 75 m high around the world.
Where does the salt in the sea come from?
Yes, some of the salt enters the water directly from the seabed. At the bottom there is a whole series of salt-containing stones, from which salt penetrates into the water. Some of the sodium chloride also comes from volcanic valves. However, according to the BBC, most of the salt comes from the mainland. Therefore, sodium chloride from land is the main reason why the sea is salty.
Each kilogram of sea water contains on average 35 g of salt. Most of this substance (about 85%) is sodium chloride, the well-known kitchen salt. Salts in the seas come from several sources:
- The first source is the weathering of rocks on the mainland; when the stones get wet, they wash away salts and other substances that rivers carry into the seas (rocks on the seabed have exactly the same effect);
- Another source is explosions of underwater volcanoes - volcanoes release lava into the water, which reacts with seawater and dissolves certain substances in it.
Water also penetrates into cracks that lie deep on the ocean floor in areas called mid-ocean ridges. The rocks here are hot and there is often lava at the bottom. In the cracks, the water heats up, due to which it dissolves a significant amount of salts from the surrounding rocks, which penetrate into the sea water.
Sodium chloride is the most common salt in seawater because it is the most soluble. Other substances dissolve less well, so there are not so many of them in the seas.
Special cases are calcium and silicon. Rivers bring large amounts of these two elements into the oceans, but despite this, they are scarce in seawater. Calcium is “picked up” by various aquatic animals (corals, gastropods and bivalves) and built into their tanks or skeletons. Silicon, in turn, is used by microscopic algae to create cell walls.
The sun shining on the oceans causes large amounts of sea water to evaporate. However, the evaporated water leaves all the salt behind. This evaporation concentrates the salt in the sea, causing the water to become salty. At the same time, some salt is deposited on the seabed, which maintains the balance of salinity in the water - otherwise, the sea would become saltier every year.
The salinity of water, or the salt content of water, varies depending on the location of the water resource. The least salty seas and oceans are near the north and south poles, where the sun does not shine as strongly and the water does not evaporate. In addition, the salt water is diluted by melting glaciers.
In contrast, the sea near the equator evaporates more due to the elevated temperatures that prevail in this area. This factor not only answers the question of why the sea is salty, but is also responsible for the increased density of water. This process is typical for some large lakes, which become saline during the process. An example is where the water is so salty and dense that people can lie quietly on its surface.
The above factors are the causes of the salinity of sea water, as scientists understand them at the current level of scientific knowledge. However, there are several unresolved issues. It is not clear, for example, why different salts are found throughout the world in essentially the same proportions, although the salinity of individual seas varies significantly.
Are these hypotheses true?
Of course, no hypothesis is completely correct. Sea water has been formed over a very long time, so scientists have no reliable evidence about the reasons for its salinity. Why can all these hypotheses be refuted? Water washes away the land where there is no such high concentration of salt. During geological epochs, the salinity of water changed. The salt content also depends on the specific sea.
Water is different - salt water has different properties. Sea – characterized by a salinity of about 3.5% (1 kg of sea water contains 35 g of salt). Salt water has different densities and freezing points vary. The average density of sea water is 1.025 g/ml, and it freezes at a temperature of -2°C.
The question may sound different. How do we know that sea water is salty? The answer is simple - everyone can easily taste it. Therefore, everyone knows the fact of salinity, but the exact reason for this phenomenon remains a mystery.
Interesting fact! If you visit Sant Carles de la Rápita and go to the bay, you will see white mountains formed from salt extracted from sea water. If mining and trade in salt water are successful, then in the future, hypothetically, the sea risks becoming a “freshwater puddle”...
Double face of salt
There are huge reserves of salt on Earth, which can be extracted from the sea (sea salt) and from mines (rock salt). It has been scientifically proven that table salt (sodium chloride) is a vital substance. Even without precise chemical and medical analyzes and research, it was clear to people from the very beginning that salt was a very valuable, useful and supportive substance that allowed both themselves and animals to survive in the world.
On the other hand, excessive salinity causes a decrease in soil fertility. It prevents plants from getting minerals into their roots. As a result of excessive soil salinity, for example in Australia, desertification is widespread.
Sea water has a not very pleasant salty and bitter taste, which makes it impossible to drink. But not every sea has the same salinity. When visiting the beach for the first time, a child often asks the question: why is the water salty? The question is simple, but it baffles parents. So, why is the water in the seas and oceans salty, what does the salinity of the water depend on.
Impact of the location of seas and oceans
If we take the planet’s seas, the water in each of them will differ in its composition. Experts say that closer to the northern regions, the salinity indicator increases. To the south, the percentage of salt content in sea water decreases. But here one thing should be remembered - ocean water is always much saltier than sea water, location does not affect this. And this fact cannot be explained by anything.
The salinity of water is due to the content of sodium and magnesium chlorides, as well as other salts. Alternatively, certain areas of land are enriched in deposits of these components, thereby differing from other regions. Frankly, this explanation is quite far-fetched, given sea currents, since salt levels should stabilize throughout the volume over time.
Reasons affecting the salt content in water
Scientists offer several explanations for the fact that the water in the seas and oceans is salty. Some people think that the high salt content is possible due to the evaporation of water from rivers flowing into the seas. Others argue that the salinity is nothing more than the result of water washing away stones and rocky areas. There are those who compare this phenomenon with the result of the action of volcanoes.
Many are skeptical about the idea that salts enter the seas with river waters. But no one denies that river water still contains salt, although not in such quantities as in the ocean.
Consequently, when river water enters the sea, a certain desalination occurs, 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, being carried further by sea currents and giving the water bitterness.
Volcanoes also have their effect. When released, they carry a decent amount of various components, including salts. Volcanic activity was especially high during the formation of the Earth. Large amounts of acid were released into the atmosphere. There is an assumption that due to the effects of acid rain, the water in the seas was initially 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 content in water. This reason is associated with winds capable of bringing salts, with a soil composition capable of passing moisture through itself, saturating it with salts, salt-releasing minerals located under the ocean floor.
Where is the most salt found?
Liquid in the form of seawater makes up the largest amount on the planet. For this reason, many people seek to relax on the sea beaches when going on vacation. Surprisingly, the mineral composition of liquids from different seas differs from each other. And there are reasons for this. So, which sea is the saltiest?
The answer to this question is provided by research statistics. The Red Sea is rightfully the saltiest 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, slightly behind the Red Sea. Ocean waters have a salt content of thirty-four grams.
What is the secret of Red Sea leadership? On average, about one hundred millimeters of precipitation falls above its surface every year. This is an insignificant amount considering that evaporation per year reaches up to two thousand millimeters.
There is no influx of water into the Red Sea from the flowing rivers due to the lack of such; replenishment occurs exclusively due to precipitation and water resources of the Gulf of Aden, where the water is also salty.
Another reason is the mixing of waters. In the winter and summer seasons, there is a change in liquid layers. Only the upper layers of water undergo evaporation. The remaining salts sink to the bottom. For this reason, their number per liter of water is constantly growing.
Sometimes the Dead Sea is called the saltiest, in which the salt percentage per unit of water reaches more than three hundred grams. This level even affects the fact that fish cannot 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.
