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 unpleasant to the taste. 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.
Baltic Sea, due to low temperatures water, contains 8 times less salt than, for example, 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.
Every kilogram sea water contains an average of 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, salts and other substances that rivers carry into the seas are washed away from them (rocks have exactly the same effect on seabed);
- Another source is explosions of underwater volcanoes - volcanoes release lava into the water, which reacts with sea water and dissolves some 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 cracks, water heats up, causing it to dissolve significant amount salts from surrounding rocks that penetrate into 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 in the northern and south poles, where the sun doesn't shine as much and the water doesn't evaporate.
In addition, the salt water is diluted by melting glaciers.
On the contrary, the sea near the equator evaporates more due to elevated temperatures which predominate 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 reasons for the salinity of sea water, as scientists understand them at the modern level 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). Salty water has different densities, and freezing points also 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 that 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 covers two-thirds of our planet and has many unique properties. Main characteristics sea water - its salinity, which differs in different parts of the planet: from 41–42 g/l in the saltiest sea to 7 g/l in the freshest. The average salinity of the World Ocean is 34.7 g/l. What is the saltiest sea in the world?
The Red Sea is the saltiest sea in the world
It is the Red Sea that is known as the saltiest sea on our planet. The density of salts in its water is 41 g/l, which is a third higher than the average salt content in the World Ocean. But this does not bother its many inhabitants. The rich flora and fauna of the Red Sea attract thousands of tourists, especially lovers of underwater tourism - diving.
By the way, if someone decides to argue with you about which sea is the saltiest - the Dead Sea, whose waters contain 270 g/l of salts, or the Red Sea, you can confidently answer that it is Red. The fact is that the Dead Sea, despite its name, is from a scientific point of view a lake, since its waters have no drainage.
In turn, the Red Sea is distinguished by the fact that it does not have a single river that flows into it. This is one of the reasons why the water in it is so salty. The climate here is very dry and hot. Water evaporates at a tremendous speed - up to 2 thousand mm per year, but the salt remains. Rains are not able to replenish this amount of evaporation: in total, less than 100 mm of precipitation falls here per year. For comparison: in the central and northern parts of Kazakhstan, 300 falls per year. – 500 mm of precipitation, in Turkey - 400 – 700 mm, in Ukraine - 600 – 800 mm, in Central Africa - 1800 – 3000 mm per year.
The Red Sea refers to the basin Indian Ocean. It would probably have dried up long ago if not for the Gulf of Aden, which allows it to exchange waters with the ocean. Currents move in both directions and replenish water balance Red Sea for thousands of liters per year. On the other hand, it is connected to the Mediterranean Sea thanks to the Suez Canal. There is also a current here, although to an insignificant extent for the scale of the sea.
Sandwiched between the northeastern coast of Africa and the Arabian Peninsula, the Red Sea stretches for more than 2 thousand km. However, even at its widest point it remains narrower than many rivers - only 360 m. In some places its depth reaches 2.2 km, although the average depth of the saltiest sea in the world is only 437 m.
Despite great length, the salinity of the waters of the Red Sea has almost the same characteristics over its entire area (which, by the way, is 450 thousand km2). This is due to the unique natural mechanism of water mixing. In winter, the cooling water sinks to the bottom, and the retaining heat rises to the top. In summer, the water on the surface becomes heavier due to evaporation and increased salinity, so this giant mixer works all year round.
Hot depressions, discovered by scientists no more than half a century ago, contribute to the mixing of water. Observations of the temperature and composition of the waters in these depressions suggest that they are heated by heat coming from the bowels of the Earth. Thus, the average water temperature in the Red Sea throughout the year remains at 20 – 25 °C, and in the depressions - 30 – 60 °C, and increases by 0.3 annually – 0.7 °C.
Rivers carry with them not only water, but also sand, silt and debris, so the Red Sea, as the only body of water in the world without river flow, retains the incredible clarity of its waters. This turns it into one of the most picturesque places on the planet. Coral reefs, thousands of species of colorful fish, numerous algae, including those that give the sea its name - all this is worth seeing with your own eyes. It is important to note that about a third of the local inhabitants are endemic, which means they can only be found here.
The saltiest seas: list
The main contenders for the status of the saltiest seas in the world are:
Mediterranean Sea.
The second place in the list of the saltiest seas after the Red Sea is occupied by the Mediterranean Sea - 39.5 g/l. Although such salinity can only be felt far from the coast, it still significantly limits the development of small algae and zooplankton, increasing the transparency of sea waters. Like the Red Sea, the Mediterranean Sea is one of the most warm seas planets: even in winter the water temperature here does not drop below 10 – 12 °C, and in summer it warms up to 25 – 28°C.
Aegean Sea.
The next in salinity is the Aegean Sea, which washes the shores of Greece and Turkey, as well as the famous island of Crete. Here the water contains an average of 38.5 g/l of salts, which are high in sodium. Doctors recommend that you rinse off after swimming in this sea to avoid corroding the surface layers of the skin.
Ionian Sea.
Another Greek sea is only slightly behind in salinity - the Ionian Sea, whose water contains on average 38 g/l of salts. Here, the high alkali content also forces tourists to be more careful about their skin. But high density (highest for seawater) combined with high temperature water (26 – 28 °C in summer) maintains the attractiveness of these places.
Ligurian Sea.
Density saline solution The Ligurian Sea also has 38 g/l. This small sea with an area of only 15 thousand km2 is located between the island of Corsica and the Tuscan coast. The many streams flowing into it from the Apennines could not add freshwater to it.
Barencevo sea.
The Barents Sea has a salinity of 35 g/l - the saltiest sea in Russia. It is located in the north of the European part of Russia and combines warm waters Atlantic Ocean and cold ones - the Arctic.
Also in the top ten saltiest seas are the Sea of Japan, known for its typhoons (37 – 38 g/l), Laptev Sea (34 g/l), Chukchi Sea (33 g/l) and White Sea (30 g/l).
Interestingly, the Aral Sea, located on the borders of Kazakhstan and Uzbekistan, which, like the Dead Sea, is more of a lake than a sea, may soon catch up with it in terms of water salinity. This reservoir, which in the mid-twentieth century occupied the 4th largest area among the planet’s lakes, became so shallow that its area decreased almost 10 times - from 68.9 thousand km2 to 7.3 thousand km2 - in 2014. During the same time, water salinity increased 10 times and in 2007 reached 100 g/l.
Despite the diversity, the salinity of the waters in the World Ocean is much more stable - over the past 50 years, scientists have not been able to notice significant fluctuations. So, when your children and grandchildren begin to wonder which sea is the saltiest in the world, the answer will remain the same - Red. We wish you to someday experience the unique composition of its waters on your own skin and see with your own eyes the diversity of its underwater inhabitants.
The Earth can be confidently called a water planet, because the World Ocean surrounding the land covers 71% of its entire surface. , included in its composition, differ from each other in many ways. Including such a parameter as salinity, which means the amount of salts dissolved in one liter of water under certain conditions. The salinity of sea water is most often measured in “‰” (ppm). Now it won’t be difficult to find out which is the saltiest sea on Earth.
5. Ionian Sea - salinity exceeds 38 ‰
The Ionian Sea is the part of the Mediterranean that washes the shores of southern Italy and Greece. The bottom of the sea is covered with silt, and closer to the shores - with sand and small shell rock. Its area is 169 thousand km², maximum depth is 5,121 m. This is the most great depth throughout the Mediterranean Sea. Commercial fishing of mackerel, mullet, tuna, and flounder is carried out. Water Ionian Sea safe and very warm, even in February their temperature does not fall below 14°C, and at the peak of the holiday season, in August, reaches 25.5°C. Among its inhabitants are bottlenose dolphins, huge turtles, and octopuses. And very dangerous sea urchins and white sharks can hardly be found near the coast. Poisonous dragon fish, which can cause an allergic reaction in humans, are more active at night and burrow into the sand during the day.
4. Aegean Sea - salinity from 37 to 40.0 ‰
This semi-enclosed sea has about 20,000 islands and is located in the eastern Mediterranean. The total area is 179 thousand km². Through the straits it is connected to Mramorny, Cherny and Mediterranean seas. The salinity of its waters is increasing, which is associated with global warming. After swimming, it is recommended to rinse off the sea water, as this can negatively affect the condition of the skin and mucous membrane of the eyes. There is a fishing industry in the Aegean Sea; sponges are actively mined and octopuses are caught. Due to the fact that there is little plankton in this sea, fishing in its waters is gradually declining.
3. Ligurian Sea - salinity 38 ‰
This sea is located in the western part of the Mediterranean. The shores are steep and rocky, but there are sandy beaches. Many small rivers flow into the Ligurian Sea, which originate in the Apennines. On its shores there are such important ports as:
- Limpia, which is considered the sea gate of Nice.
- Cruise ports of Savona, La Spezia, with container and bulk terminals.
- Genoese port, ranking first in terms of trade volume in Italy.
Despite the high salinity of these waters, on the French-Italian coast of the Ligurian Sea is located one of the most famous resort areas in the world - the Riviera.
2. Mediterranean Sea - salinity from 36 to 39.5 ‰
The Mediterranean Sea is a relic of the ancient Tethys Ocean. It is considered one of the largest seas in size, its area is 2.5 million km². Its basin includes the Sea of Azov, Black and Marmara. The salinity of the sea fluctuates significantly, as water with a much lower salinity enters from the Atlantic through the Strait of Gibraltar. The amount of zooplankton in the Mediterranean Sea is relatively small, and as a result there are few various types fish, as well as marine animals and mammals. But in large quantities algae are represented, especially peridinea and diatoms. The bottom fauna is very poor due to yellowish silt, which is not conducive to the development of life. There are 550 species of fish in the Mediterranean Sea, 70 of which are endemic. The most common species are: mackerel, sardine, horse mackerel, mullet, etc. There are also larger “inhabitants” - sharks, rays, tuna. Edible shellfish are common.
1. Red Sea - salinity 41 ‰
The saltiest of all, the Red Sea is located in a tectonic depression, the depth of which can reach 3 km. It is an inland sea of the Indian Ocean. The hot climate, which provokes strong surface evaporation and low precipitation (about 100 mm per year), and the absence of rivers flowing into the sea, leads to a gradual increase in its salinity. Due to the absence of silt and sand, which are abundant in river water, the Red Sea is distinguished by its extraordinary transparency and cleanliness. The water temperature even in winter is +20 °C, and in summer it is much higher.
Despite its salinity, the waters of the Red Sea amaze with the huge number of different species of fish living in it. But ichthyologists believe that only 60% of fish capable of existing at great depths have been discovered. The sea is extremely beautiful, and it has many interesting and sometimes funny inhabitants, but touching them is strictly prohibited. Corals, sponges, jellyfish, and sea urchins, moray eels and poisonous sea snakes potentially extremely dangerous. Any contact with them can result in a burn, significant blood loss or severe allergic reaction, and sometimes fatal. 44 species of sharks live in warm sea waters. The most terrible of them is the tiger, which can easily attack a person.
Having examined them separately, it is now easy to conclude which is the saltiest sea. The saltiness of the very famous Dead Sea reaches 350 ‰, but in fact, despite the name, it is an endorheic lake that is gradually drying up.
Rating of seas by salinity
There are about 80 seas on our planet. Of course, the Dead Sea would take first place in the ranking, since its waters are famous for their salinity. The Dead Sea is one of the saltiest bodies of water on Earth, salinity is 300-310 ‰, in some years up to 350 ‰. But scientists call this body of water a lake.
- Red Sea with a salinity of 42‰.
The Red Sea is located between the shores of Africa and Asia. The Red Sea, in addition to its salinity and warmth, boasts its transparency. Many tourists love to relax on its shores.
2. The Mediterranean Sea has a salinity of 39.5‰.
The Mediterranean Sea washes the shores of Europe and Africa. In addition to salinity, it can also boast of its warm waters– in summer they warm up to 25 degrees above zero.
3. Aegean Sea with a salinity of 38.5‰.
The waters of this sea with a high concentration of sodium can cause skin irritation. Therefore, after swimming it is better to take a fresh shower. In summer, the water warms up to 24 degrees Celsius. Its waters wash the shores of the Balkan Peninsula, Asia Minor and the island of Crete.
4 . Ionian Sea with a salinity of 38 ‰.
This is the densest and saltiest Greek sea. Its waters allow slow swimmers to hone this skill, as the high density will help keep the body afloat. The area of the Ionian Sea is 169 thousand square kilometers. It washes the shores of Southern Italy, Albania and Greece.
5 . The Sea of Japan, whose salinity is 35‰
The sea is located between the continent of Eurasia and the Japanese islands. Its waters also wash the island of Sakhalin. Water temperature depends on geographical location: in the north – 0 -+12 degrees, in the south – 17-26 degrees. The area of the Sea of Japan is more than 1 million square kilometers.
6. Barents Sea with salinity 34.7-35 ‰
This is the marginal sea of the Arctic Ocean. It washes the shores of Russia and Norway.
7. Laptev Sea with a salinity of 34‰.
Area - 662 thousand square kilometers. It is located between the New Siberian Islands and Severnaya Zemlya. The average annual water temperature is 0 degrees Celsius.
8. Chukchi Sea with a salinity of 33‰.
In winter, the salinity of this sea rises to 33‰, while in summer the salinity decreases slightly. The Chukchi Sea has an area of 589.6 thousand km². average temperature in summer - 12 degrees Celsius, and in winter - almost 2 degrees Celsius.
9. White Sea also different high salinity. In the surface layers the figure stopped at 26 percent, but at depth it increases to 31 percent.
10. Laptev Sea. Salinity at the surface is recorded at 28 percent
The sea has a harsh climate with temperatures below 0°C for more than nine months of the year, sparse flora and fauna, and low population along the coast. Most of the time, with the exception of August and September, it is under ice. The salinity of sea water at the surface in the northwestern part of the sea in winter is 34 ‰ (ppm), in the southern part - up to 20-25 ‰, decreasing in summer to 30-32 ‰ and 5-10 ‰, respectively. The salinity of surface waters is strongly influenced by the melting of ice and the runoff of Siberian rivers.