Sea water, billions of years ago, having dissolved a lot of chemical compounds, transformed into a solution containing many unique microcomponents. One of the main characteristics of sea water is its salinity. The Mediterranean Sea is the most s alty on the planet after the Red Sea.
A bit of history
The Mediterranean Sea, according to scientists, was once part of the Tethys, the oldest ocean that stretched from America to Asia.
Five million years ago, due to a severe drought, the sea was a lot of lakes and began to flood only at the end of the drought, many years later. This was facilitated by a gigantic waterfall that cut through the barrier that served as a barrier between the sea and the Atlantic Ocean. Gradually, as the sea filled with the waters of the Atlantic Ocean, this obstacle disappeared and the Strait of Gibr altar was formed.
Characteristic
The Mediterranean Sea is located between Africa and Europe, and its outlines all the timeare subject to change. Today:
- its area is 2.5 million km2;
- water volume - 3.6 million km3;
- average depth - 1541 m;
- maximum depth reaches 5121m;
- water transparency 50-60 m;
- salinity of the Mediterranean Sea as a percentage in some places reaches 3.95%;
- total annual river flow 430 km3.
This is one of the warmest and s altiest areas of the World Ocean.
The Mediterranean Sea got its name because of its location among the lands that made up the whole world known to the ancients. The sea in the middle of the Earth - so the ancient Greeks called it, the Romans called it the Inland Sea, or Ours. Big green water - this is how the ancient Egyptians called the reservoir.
Composition of water
Sea water is not just H2O, but a solution of a myriad of substances, where many chemical elements are combined in various formulas. Of these, the largest amount is chlorides (88.7%), among which NaCl is the leader - ordinary table s alt. Sulfuric acid s alts - 10.8%, and only 0.5% of the rest of the water composition form other substances. These proportions predetermine the salinity of the Mediterranean Sea. In ppm, this figure is 38‰. This allows you to get table s alt from sea water by evaporating it.
During the many years of development of life on Earth, sea water became a supplier of s alt, transforming into s alt layers. One of the largest s altEurope's mines are located in Sicily, the largest island in the Mediterranean.
S alt deposits can be formed at different depths, which sometimes reach 1 km, and in some cases they are s alt lakes at the level of the Earth's surface - the Uyuni s alt marsh, a dry s alt lake.
Oceanographers have found that the World Ocean contains 48 quadrillion tons of s alt, and even with constant extraction of s alt, the composition of sea water will not change.
The concept of salinity
Determining the salinity of the Mediterranean Sea, as well as other water bodies, take into account the mass of s alts in grams contained in one kilogram of sea water.
It is calculated in ppm and is due to the fact that a large volume of river water or melted continental glaciers enters the seas. The low salinity of the equatorial zone is due to tropical rains that desalinate the water.
Salinity changes with increasing depth. Further 1500 meters it is almost gone.
To take a sample, to measure it, special samplers are used that allow you to take samples from different depths and from different water layers.
Why so much s alt in sea water
Some time scientists were of the opinion that rivers brought s alt, but this hypothesis was not confirmed. The only assumption that is now held is that the ocean became s alty during its birth and transformation, since ancient animals could not live in fresh or slightly s alty water. On theAt the bottom of the Mediterranean Sea, near the Greek city of Zakynthos, organized structures were found that are more than three million years old, but what was the percentage of salinity of the Mediterranean Sea in those days is unknown.
Academician V. I. Vernadsky believed that marine inhabitants - animals and plants - extracted silicon s alts and carbon dioxide from the deep sea, which rivers brought to form their shells, skeletons and shells. And as they died away, these same compounds settled on the seabed in the form of organic sediments. Thus, marine life has kept the s alt composition of sea water unchanged for centuries.
What causes salinity
All seas are part of the ocean. But there are seas that break deep into the land and are connected with the ocean only by a narrow strait. These seas include:
- Mediterranean;
- Black;
- Azov;
- B altic;
- Red.
They can all be either very s alty, because they are affected by hot air, or almost fresh because of the rivers flowing into them, which dilute them with their water.
The salinity of the Black and Mediterranean Seas is largely influenced by the hot climate.
Despite the fact that the Black Sea is located in the Mediterranean basin and is connected to it by the shallow straits of the Dardanelles and the Bosporus, it has a lower salinity. The indicator is lower not only as a result of difficult water exchange with the Atlantic Ocean, but also due todue to a significant amount of precipitation and inflow of continental waters. In the open part of the sea, this indicator varies from 17.5‰ to 18‰, and in the coastal strip of the North-Western region, it is below 9‰.
The salinity of the seas differs from the salinity of ocean waters, which is due to free water exchange between the seas and the ocean, water runoff and climate influence. On the surface of the Mediterranean Sea, water salinity increases in the segment from the Strait of Gibr altar to the coast of Egypt and Syria, and near Gibr altar it reaches 36‰.
Climate
Due to the location of the Mediterranean Sea in the subtropical zone, the Mediterranean climate prevails here: hot summers and mild winters. The January air temperature on the northern coasts of the sea is around +8..+10 °С, and on the southern coast it is +14…+16 °С. The hottest month is August, when the maximum temperature near the eastern coast reaches +28…+30 °С. The winds blow over the sea all year round, and in the winter, cyclones from the Atlantic invade, creating storms.
Sirocco breaks out of the African deserts, a sultry wind that carries a lot of dust and the temperature often reaches +40°C and above. All these factors affect the salinity of the Mediterranean Sea, increasing its percentage due to water evaporation.
Fauna
The fauna of the Mediterranean Sea is characterized by a wide variety of species. This is due to a favorable environment and a long history. More than 550 species of fish live here, 70 of which live in a limited range.
Huge shoals are concentrated here during the winter, and inthe rest of the year, individuals are scattered, especially during spawning or fattening. To do this, numerous species of fish migrate to the Black Sea.
The southeastern region of the Mediterranean Sea, influenced by the flow of the Nile River, is one of the most fertile. The waters of the Nile generously supplied sea water with a large amount of nutrients and mineral suspensions, which affected the salinity of the Mediterranean Sea.
But in the early sixties, the Aswan hydroelectric power station was built, as a result of which the river flow and the redistribution of water during the year were sharply reduced. This significantly worsened the living conditions of marine individuals, and their numbers decreased. Since the desalination zone has decreased, useful s alts began to enter the sea in a smaller volume. This led to a significant reduction in the number of zoo- and phytoplankton, respectively, the number of fish (sardines, mackerels, horse mackerels, etc.) decreased and fishing decreased.
Unfortunately, the pollution of the Mediterranean Sea is increasing in direct proportion to the development of technological progress, and the environmental situation causes concern among scientists. Let's hope that all caring people unite and preserve the we alth of the sea world for posterity.
