The Mediterranean Sea is salty or fresh. Mediterranean Sea

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In the section on the question, help with the rating of sea salinity given by the author Staff the best answer is According to personal feelings - Mediterranean, more salty Aegean, the saltiest - Red. Then - Dead. And % - you need to look...
Salinity is the amount of solids in grams dissolved in 1 kg of sea water, provided that all halogens are replaced by an equivalent amount of chlorine, all carbonates are converted to oxides, and organic matter is burned.
It is measured in “‰” (“ppm”).
The average salinity of the world's oceans is 35 ‰. To calibrate instruments, so-called normal water with a salinity close to 35 ‰ is extracted from the Bay of Biscay.
Baltic - 7-8
Azovskoe - 12
Black - 16
Mramornoe 26
Adriatic - 35-38
Aegei 37
Ligurian -38
Mediterranean (overall) about 38 - 39.5
Red - 39-40
Dead 260-270
Source Wikipedia and:

Answer from Neurologist[guru]
Aegean Sea
Salinity 37.0-39.00/00.
Mediterranean Sea
Large evaporation leads to a strong increase in salinity. Its values increase from 3. to V. from 36 to - 39.5. The density of water on the surface varies from 1.023-1.027 g/cm³ in summer to 1.027-1.029 g/cm³ in winter.
Red sea
Strong evaporation from warm water turned the Red Sea into one of the saltiest in the world. globe: 38-42 grams of salts per liter. Salinity - 40-60 g/l. Salt content reaches up to 40‰
Dead Sea
The content of minerals in water reaches 33%, an average of 28% (for comparison in the Mediterranean Sea - 4%).
Barencevo sea
The salinity of the surface layer of water in the open sea throughout the year is 34.7-35.0‰ in the southwest, 33.0-34.0‰ in the east, and 32.0-33.0‰ in the north. In the coastal strip of the sea in spring and summer, salinity drops to 30-32 ‰, and by the end of winter it increases to 34.0-34.5 ‰.
Sea of Azov
The salinity of the sea before the regulation of the Don was three times less than the average salinity of the ocean. Its value on the surface varied from 1 ppm at the mouth of the Don to 10.5 ppm in the central part of the sea and 11.5 ppm near the Kerch Strait. After the creation of the Tsimlyansky hydroelectric complex, the salinity of the sea began to increase (up to 13 ppm in the central part). Average seasonal fluctuations in salinity rarely reach 1-2 percent.
Davis Sea
Salinity 33.0-33.5‰.
Baltic Sea
The salinity of sea water decreases from the Danish Straits, connecting the Baltic Sea with the salty North Sea, to the east. In the Denmark Straits, salinity is 20 ppm at the surface of the sea and 30 ppm at the bottom. Towards the center of the sea, salinity decreases to 6-8 ppm at the sea surface, in the north of the Gulf of Bothnia it drops to 2-3 ppm, in the Gulf of Finland to 2 ppm. Salinity increases with depth, reaching 13 ppm in the center of the sea near the bottom.
White Sea
The large influx of river water and insignificant exchange with the Barents Sea led to a relatively low salinity of the surface waters of the sea (26 ppm and below). The salinity of deep waters is much higher - up to 31 ppm.
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Answer from luxury[guru]
For me, the Dead is the saltiest. And then Ionian, Aegean, Mediterranean.

There are about 80 seas throughout our planet. All of them enter the waters of the World Ocean. As everyone knows from school, the seas are salty, but they all differ in the saturation of different compounds. Below is a ranking of the saltiest seas on Earth.

The White Sea, whose salinity is ‰.

One of the smallest seas on the planet is also one of the saltiest. Its area is only 90 thousand square kilometers. The water in it warms up to 15 degrees above zero in summer, and drops to 1 degree Celsius in winter. About 50 species of fish live in the White Sea.

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The Chukchi Sea with a salinity of 33‰.

In winter, the salinity of this sea increases to 33‰, while in summer the salinity decreases slightly. The Chukchi Sea has an area of 589.6 thousand square kilometers. The average temperature in the warm season is 12 degrees Celsius, in the cold season - almost 2 degrees Celsius.

The area of this sea is 662 thousand square kilometers. It is located between the New Siberian Islands and Severnaya Zemlya. The average annual water temperature is 0 degrees Celsius.

The Barents Sea has a salinity of 35‰.

The Barents Sea is the saltiest of all located in the territory Russian Federation. It is adjacent to, but is almost 16 times larger in area. The waters are full different types fish due to the fact that the water temperature in summer is about 12 degrees Celsius. And this attracts many marine organisms, which, in turn, attract predatory fish.

The Sea of Japan, whose salinity is 35‰, is in 6th place in our ranking.

This sea is located between the continent of Eurasia and the Japanese islands. Its waters also wash the island of Sakhalin. The Sea of Japan is considered one of the saltiest seas in the world. The water temperature differs depending on geographical location: in the north – 0 -+12 degrees, in the south – 17-26 degrees Celsius. The area of the Sea of Japan is more than 1 million square kilometers.

The Ionian Sea is 3‰ higher in salinity than our previous record holder.

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. IN summer period the water warms up to 26 degrees above zero. The area of the Ionian Sea is 169 thousand square kilometers.

Aegean Sea with a salinity of 38.5‰.

This sea takes 4th place in our ranking. Its waters with a high concentration of sodium can cause irritation to human skin. Therefore, after bathing in it, you should take a fresh shower. In summer, the water warms up to 24 degrees Celsius. Its waters wash the shore Balkan Peninsula, Asia Minor and the island of Crete. The Aegean Sea, more than 20 thousand years old, has an area of 179 thousand square kilometers.

The Mediterranean Sea has a salinity of 39.5‰.

Red Sea with a salinity of 42‰.

It is located between the coasts of Africa and Asia. All year round warm waters provide favorable conditions for many fish and other marine organisms. The Red Sea, in addition to salinity and warmth, boasts. Many tourists love to relax on its shores.

The Dead Sea has a record salinity of 270‰.

Israel has the saltiest water on our planet. Its salinity of 270% makes it the densest on Earth. The mineral content helps people heal all sorts of ailments, but you should not stay in the water for too long - this can have a detrimental effect on a person's skin.

Mikhail Ilyin

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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 greatest depth in the entire Mediterranean Sea. Commercial fishing of mackerel, mullet, tuna, and flounder is carried out. The waters of the Ionian Sea are 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. total area- 179 thousand km². Through the straits it is connected to the Marmara, Black 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 different species of fish, as well as marine animals and mammals. But algae are present in large numbers, 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, as well as sea urchins, moray eels and poisonous sea snakes are potentially extremely dangerous. Any contact with them can result in a burn, significant blood loss or a severe allergic reaction, and sometimes death. 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 salinity of the very famous Dead Sea reaches 350 ‰, but in fact, despite its name, it is an endorheic lake that is gradually drying up.

Mediterranean Sea

The Inland Mediterranean Sea is located between 30 and 45° N latitude. and 5.3 and 36° E.

It is deeply cut into the land and represents one of the most isolated large sea basins in the World Ocean. In the west, the sea communicates with the Atlantic Ocean through the narrow (15 km wide) and relatively shallow Strait of Gibraltar (depths at the threshold to the west of the strait are about 300 m); in the northeast - with the Black Sea through the even shallower straits of the Bosphorus (the depth of the threshold is less than 40 m) and the Dardanelles (the depth of the threshold is about 50 m), separated by the Sea of Marmara. The transport connection between the Mediterranean Sea and the Red Sea is carried out through the Suez Canal, although this connection has practically no effect on the processes occurring in the sea.

At the entrance to the Suez Canal

The area of the Mediterranean Sea is 2,505 thousand km 2, the volume is 3,603 thousand km 3, the average depth is 1438 m, the greatest depth is 5121 m.

The complex contours of the coastline, a large number of peninsulas and islands of different sizes (among which the largest are Sicily, Sardinia, Cyprus, Corsica and Crete), as well as the highly dissected bottom topography, determine the division of the Mediterranean Sea into several basins, seas and bays.

In the Venetian lagoon

Apennine Peninsula and about. Sicily is divided by the sea into two basins. In the western basin, the Tyrrhenian Sea is distinguished, and in a number of works also the Alboran Sea, the Balearic (Iberian) Sea, the Gulf of Lion, the Ligurian Sea and the Algerian-Provencal basin. The shallow Tunisian (Sicilian) Strait and the narrow Strait of Messina connect the western basin of the sea with the eastern, which in turn is divided into central and eastern. In the northern part of the central basin is the Adriatic Sea, which communicates through the Strait of Otranto with the Ionian Sea, which occupies the central part of the basin. In its southern part there are the gulfs of Greater and Lesser Sirte. The Creto-African Strait connects the central basin of the sea with the eastern one, often called the Sea of Levant. In the northern part of the eastern basin is the island-rich Aegean Sea.

Turkish port of Alanya in the Mediterranean Sea

Relief north coast the seas are complex and varied. The shores of the Iberian Peninsula are high, abrasive, and the Andalusian and Iberian mountains come close to the sea. Along the Gulf of Lyon, west of the Rhone delta, there are swampy lowlands with numerous lagoons. To the east of the Rhone, spurs of the Alps approach the sea, forming shores with rocky headlands and small bays. The western coast of the Apennine Peninsula along the Tyrrhenian Sea is quite rugged, steep and steep banks alternate with low ones, and there are flat alluvial lowlands composed of river sediments. The eastern shores of the Apennine Peninsula are more leveled, in the north they are swampy, low, with a large number lagoons, in the south - high and mountainous.

Strong ruggedness and complexity of the relief are characteristic of the entire coast of the Balkan Peninsula. High, steep shores with small bays predominate; a huge number of small islands are scattered along the coast in the sea. Same difficult terrain It also has a coastline on the Asia Minor Peninsula from the Aegean Sea, while the southern shores of the peninsula are composed of larger landforms. The entire eastern coast of the sea is flat, without capes or bays.

The southern coast of the Mediterranean Sea, in contrast to the northern one, is much more leveled, especially the smoothed relief in the eastern basin of the sea. In the west the shores are high, and the Atlas Mountains stretch along the sea. Towards the east, they gradually decrease and are replaced by low-lying sandy shores, the landscape of which is characteristic of the huge African deserts located to the south of the sea. Only in the southeastern part of the sea, in the vicinity of the Nile delta (about 250 km), is the coast composed of sediments from this river and has an alluvial character.

Climate

The Mediterranean Sea is located in a subtropical climate zone; coastal mountain systems prevent the invasion of cold air masses from the north. In winter, a pressure trough stretches over the sea from west to east, around which centers of high pressure are located. In the west there is a spur of the Azores anticyclone, in the north there are spurs of the European High. The pressure is also increased over North Africa. Intensive formation of cyclones occurs along the frontal zone.

In summer, a ridge of high water levels forms over the Mediterranean Sea. atmospheric pressure, and only over the Levant Sea there is an area of low pressure.

A clearly defined seasonal change in wind directions is observed only along the southern shores of the western part of the Mediterranean Sea, where predominantly westerly winds blow in winter and easterly winds in summer. Over most areas of the sea, north-west winds prevail all year round, and over the Aegean Sea - north and north-east.

In winter, due to the development of cyclonic activity, there is a significant recurrence of storm winds; in summer, the number of storms is insignificant. The average wind speed in winter is 8-9 m/s, in summer about 5 m/s.

Some areas of the sea are characterized by different local winds. In the eastern regions in summer season Steady northerly winds (aethesia) are observed. In the area of the Gulf of Lyon, the mistral is often repeated - a cold, dry north or northwest wind of great strength. The eastern coast of the Adriatic Sea is characterized by bora - a cold, dry northeast wind, sometimes reaching the strength of a hurricane. The warm southerly wind from the deserts of Africa is known as sirocco.

It carries a large amount of dust, causes an increase in air temperature to 40-50° and a drop in relative humidity to 2-5%. Most of the Mediterranean coast has strong breezes.

The most low temperature air - in January: it varies from 14-16° on the southern coast of the sea to 7-8° in the north of the Aegean and Adriatic seas and to 9-10° in the north of the Algerian-Provencal basin.

In the summer season the most heat observed in August. This month it rises from 22-23° in the north of the Algerian-Provencal basin to 25-27° on the southern coast of the sea, and reaches a maximum (28-30°) off the eastern shores of the Levant Sea. In most of the Mediterranean Sea, the average annual change in air temperature is relatively small (less than 15°), which is a sign of a maritime climate.

The amount of precipitation over the sea decreases in the direction from northwest to southeast. Near the European coast, annual precipitation exceeds 1000 mm, and in the southeast of the sea it is less than 100 mm. Most of the annual precipitation falls in the autumn-winter months; in summer, rain is very rare and has the character of thunderstorms.

Hydrology

River flow along most of the coast is low. The main rivers flowing into the sea are the Nile, Rhone and Po.

In general, due to the predominance of evaporation over precipitation and river runoff, a freshwater deficit is created in the sea. This leads to a decrease in level, which in turn causes compensatory inflow water from Atlantic Ocean and the Black Sea. At the same time, in the deep layers of the Strait of Gibraltar and the Bosphorus, saltier and denser Mediterranean waters flow into neighboring basins.

Sea level

Seasonal changes in sea level are insignificant, their average annual value for the entire sea is about 10 cm, with a minimum in January and a maximum in November.

Tides in the Mediterranean Sea are predominantly semidiurnal and irregular semidiurnal; only in some areas of the northeastern coast of the Adriatic Sea are diurnal tides observed. The tide in most of the water area does not exceed 1 m. The highest tides are recorded in the area of the Strait of Gibraltar and the Alboran Sea (from 3.9 to 1.1 m). Tidal currents in the open sea are weakly expressed, but in the Straits of Gibraltar, Messina and Tunis they reach significant values.

Non-periodic level fluctuations caused by storm surges (sometimes in combination with high tide) can reach large values. In the Gulf of Lyon, with strong southern winds, the level can rise by 0.5 m; in the Gulf of Genoa, with a stable sirocco, a rise of up to 4 m is possible. Almost the same increase in level (up to 3.5 m) is observed with storm winds of the southwestern quarter in the northern parts of the Tyrrhenian Sea. In the Adriatic Sea, with southeastern winds, the level can rise to 1.8 m (for example, in the Venetian Lagoon), and in the bays of the Aegean Sea, with strong southern winds, the range of surge fluctuations reaches 2 m.

The strongest waves in the sea develop in autumn and winter, during the period of active cyclonic activity. At this time, the wave height quite often exceeds 6 m, and in strong storms reaches 7-8 m.

Bottom relief

The topography of the seabed has many morphological features characteristic of an oceanic basin. The shelf is quite narrow - mostly no wider than 40 km. The continental slope along most of the coast is very steep and cut by submarine canyons. Most of the western basin is occupied by the Balearic Abyssal Plain with an area of about 80 thousand km 2. In the Tyrrhenian Sea there is a central abyssal plain, on which many seamounts stand out. The highest seamount rises 2850 m above the sea floor. The peaks of some mountains on the mainland slope of Sicily and Calabria rise above the surface of the sea, forming the Aeolian Islands.

The morphology of the bottom of the eastern basin of the sea differs markedly from the morphology of the western basin. In the eastern basin, vast areas of the bottom represent either a complexly dissected median ridge or a series of deep-sea depressions. These depressions stretch from the Ionian Islands, south of the islands of Crete and Rhodes. In one of these depressions the greatest depth of the Mediterranean Sea is located.

Currents

Circulation on the surface of the Mediterranean Sea is formed by Atlantic waters entering the sea through the Strait of Gibraltar and moving east along the southern shores in the form of the meandering North African Current. On its left side there is a system of cyclonic gyres, on the right - anticyclonic ones. The most stable cyclonic gyres in the western basin of the sea are formed in the Alboran Sea, the Algerian-Provencal basin, and the Tyrrhenian Sea; anticyclonic - off the coast of Morocco and Libya.

Through the Strait of Tunis, Atlantic waters enter the central and eastern basins of the sea. Their main flow continues to move along the African coast, and part of it deviates to the north - into the Ionian and Adriatic, as well as into the Aegean Sea, being drawn into complex system cyclonic gyres. Among them, the Ionian, Adriatic, Athos-Chios, Cretan (in the Aegean Sea) and Levantine gyres should be mentioned. To the south of the North African Current, anticyclonic gyres are distinguished in the gulfs of Little and Greater Sirte and the Cretan-African one.

In the intermediate layer, Levantine water moves from the eastern basin of the sea to the west, towards the Strait of Gibraltar. However, the transfer of Levantine waters from east to west does not occur in the form of a single intermediate countercurrent, but in a complex way, through a system of numerous circulations. Two-layer, oppositely directed flows of Atlantic and Levantine waters are clearly visible only in the Straits of Gibraltar and Tunis.

The average speeds of the resulting water transfer are low: in the upper layer - up to 15 cm/s, in the intermediate layer - no more than 5 cm/s.

In the deep layers, water moves weakly from the formation centers in the northern regions of the sea to the south, filling the sea basins.

Vertical distribution of salinity (‰) on a longitudinal section through the Strait of Gibraltar (arrows - current directions)

The nature of water exchange in the straits plays an important role in the formation of the hydrological structure of waters in different basins of the Mediterranean Sea. Thus, the depth of the threshold in the Strait of Gibraltar completely isolates the Mediterranean Sea from the influx of cold deep waters of the Atlantic Ocean. Atlantic waters cover layers from the surface to 150-180 m, current speeds in which are 20-30 cm/s, in the narrowest part of the strait - up to 100 cm/s, and sometimes significantly higher. Intermediate Mediterranean waters move in the deep part of the strait relatively slowly (10-15 cm/s), but above the threshold their speed increases to 80 cm/s.

The Strait of Tunis, with depths above the rapids of no more than 400-500 m, is important for water exchange between the western and eastern parts of the sea. This excludes the exchange of deep waters in the western and central basins of the sea. In the strait area surface layer Atlantic waters are transferred to the east, and in the bottom layer, Levantine waters flow through the rapids in a westerly direction. The transport of Levantine waters predominates in winter and spring, and that of Atlantic waters in summer. The two-layer water exchange in the strait is often disrupted, and the current system becomes very complex.

The Strait of Otranto, in the form of a narrow trench, connects the Adriatic and Ionian seas. The depth above the threshold is 780 m. Water exchange through the strait has seasonal differences. In winter, at depths of more than 300 m, water moves from the Adriatic Sea; at a horizon of 700 m, speeds of 20-30 cm/s are recorded. In summer, in the deep layers of the strait, a current from the Ionian Sea to the north is observed at a speed of 5-10 cm/s. However, even in summer there may be a southerly current in the bottom layer above the threshold.

The Bosphorus and Dardanelles straits, as well as the Sea of Marmara, connect the Mediterranean Sea (via the Aegean) with the Black Sea. The shallow depth in the straits significantly limits water exchange between the Mediterranean and Black Seas, the hydrological conditions of which are very different. Water exchange in the straits is determined by differences in water density, differences in levels of neighboring seas, and synoptic conditions.

The denser, highly saline waters of the Aegean Sea in the bottom layers of the Dardanelles Strait penetrate into the basin of the Sea of Marmara, fill it and then enter the Black Sea in the bottom layer of the Bosphorus Strait. Desalinated, much less dense Black Sea waters flow into the Aegean Sea with a surface current. Throughout the straits there is a sharp vertical density stratification of water layers.

The boundary of multidirectional flows rises from north to south from 40 m at the entrance to the Bosphorus to 10-20 m at the exit from the Dardanelles. The highest flow rate of Black Sea water is observed on the surface and quickly decreases with depth. Average speeds are 40-50 cm/s at the entrance to the strait and 150 cm/s at the exit. The lower current carries the waters of the Mediterranean Sea at a speed of 10-20 cm/s in the Dardanelles and 100-150 cm/s in the Bosphorus.

The influx of Black Sea waters into the Mediterranean Sea is approximately two orders of magnitude less than the influx of Atlantic waters. As a result, the waters of the Black Sea influence the hydrological structure only within the Aegean Sea, while the Atlantic waters are present almost everywhere, right up to the eastern regions.

Water temperature

In summer, the surface water temperature increases from 19-21° in the northwestern part of the sea to 27° and even higher in the Levant Sea. This temperature pattern is associated with increasing continentality of the climate with distance from the Atlantic Ocean.

In winter, the general nature of the spatial distribution of temperature remains the same, but its values are significantly lower. In February, in the northwestern part of the sea and in the north of the Aegean Sea, the temperature is 12-13°, and off the northern shores of the Adriatic it even drops to 8-10°. The highest temperatures are observed off the southeastern coast (16-17°).

The magnitude of annual fluctuations in water temperature in the surface layer decreases from 13-14° in the north of the Adriatic Sea and 11° in the Aegean Sea to 6-7° in the area of the Strait of Gibraltar.

The thickness of the upper, heated and mixed layer in summer in cyclonic gyres is 15-30 m, and in anticyclonic gyres it increases to 60-80 m. At its lower boundary there is a seasonal thermocline, under which a decrease in temperature occurs.

During winter cooling, convective mixing actively develops in the sea. In the Algerian-Provencal basin and some other northern areas of the sea, convection extends to great depths (2000 m or more) and contributes to the formation of deep waters. Favorable conditions for the development of convection also exist in the Tyrrhenian, Ionian and Levantine seas, where it covers a layer of up to 200 m, sometimes more. In other areas, winter vertical circulation is limited to the upper layer, mainly up to 100 m.

Spatial differences in temperature decrease rapidly with depth. Thus, at a horizon of 200 m, its values vary from 13° in the western part of the sea to 15° in the central basin and to 17° in the Levant Sea. Seasonal temperature changes at this depth are no more than 1°.

Water temperature on a latitudinal section in the Mediterranean Sea in summer

In the layer of 250-500 m there is a maximum temperature associated with the spread of warm and salty Levantine waters. In summer, it appears over most of the sea, with the exception of the eastern basin and the southern part of the Aegean Sea; in winter it is less pronounced. In this layer, the temperature drops from 14.2° in the Strait of Tunis to 13.1° in the Alboran Sea.

The deep water column is characterized by a very uniform temperature. At a horizon of 1000 m its values are 12.9-13.9°, in the bottom layer - 12.6-12.7° in the Algerian-Provencal basin and 13.2-13.4° in the Levant Sea. In general, the temperature of the deep waters of the Mediterranean Sea is characterized by high values.

Salinity

The Mediterranean Sea is one of the saltiest in the World Ocean. Its salinity almost everywhere exceeds 36‰, reaching 39.5‰ on the eastern shores. Average salinity is about 38‰. This is due to a significant fresh water deficit.

Salinity on the sea surface generally increases from west to east, but in the northern regions of the sea it is higher than along the African coast. This is explained by the spread of less saline Atlantic waters along the southern coasts to the east. The difference in salinity between the northern and southern regions of the sea reaches l‰ in the west and decreases to 0.2‰ in the Levant Sea. However, some coastal areas in the north are influenced by river flow (Gulf of Lion, northern Adriatic Sea) or desalinated Black Sea waters (northern Aegean Sea) and are characterized by low salinity.

The Levant Sea and the southeastern Aegean Sea experience the highest salinity in summer, due to intense evaporation. In the central basin, where Levantine and Atlantic waters mix, there are large salinity ranges (37.4-38.9‰). Minimum salinity is in the western basin experiencing direct influence Atlantic Ocean. It varies here from 38.2‰ in the Ligurian Sea to 36.5‰ in the Alboran Sea.

Salinity on a latitudinal cross-section in the Mediterranean Sea in summer. 1 - advection of Atlantic waters; 2 - advection of Levantine waters

In winter, salinity is distributed basically the same as in summer. Only in the Levant Sea does it decrease slightly, and in the western and central basins does it increase. The magnitude of seasonal changes in surface salinity is about 1‰. As a result of the development of wind and convective mixing in winter, a layer of uniform salinity is formed, the thickness of which varies from region to region.

Almost the entire Mediterranean Sea is characterized by the existence of a salinity maximum, the formation of which is associated with Levantine water. The depth of its occurrence increases from east to west from 200-400 to 700-1000 m. Salinity in the maximum layer gradually decreases in the same direction (from 39-39.2‰ in the eastern basin to 38.4‰ in the Alboran Sea).

In the water column deeper than 1000 m, salinity remains virtually unchanged, remaining within the range of 38.4-38.9‰.

There are three main water masses in the Mediterranean Sea: Atlantic surface water, Levantine intermediate water and deep waters of the western and eastern basins.

The Atlantic water mass is present in almost all parts of the sea, occupying upper layer 100-200 m thick, sometimes up to 250-300 m. The core of the Atlantic waters, characterized by a minimum salinity in summer, is mainly located at horizons of 50-75 m, which mostly corresponds to the thermocline layer. In winter, the depth of its occurrence increases in the direction from west to east from 0-75 to 10-150 m. The temperature in the core in summer in the western basin is 13-17 °, in the eastern - 17-19 °, in winter - 12-15 and 16, respectively ,9°. Salinity increases from west to east from 36.5-38.5 to 38.2-39.2‰.

The Levantine intermediate water mass is distinguished throughout the entire sea area in a layer of 200-700 m and is characterized by a maximum salinity. It is formed in the Levant Sea, where intense salinization of the surface layer of water occurs in summer. During the cold season, this layer cools and, during the development of winter vertical circulation, sinks to intermediate horizons. From the place of formation, Levantine water moves towards the Strait of Gibraltar towards the surface Atlantic water. The speed of movement of Levantine waters is several times less than that of the Atlantic (about 4-5 cm/s); it takes about three years to travel to the Strait of Gibraltar.

The core of intermediate water descends as it moves west from 200-300 m in the eastern basin to 500-700 m near Gibraltar. The temperature in the core decreases accordingly from 15-16.6 to 12.5-13.9°, and salinity - from 38.9-39.3 to 38.4-38.7‰.

Deep waters are formed in the northern regions of the Mediterranean Sea due to winter cooling and the intensive development of convective mixing, reaching depths of 1500-2500 m in some areas. These areas include the northern part of the Algerian-Provencal basin, the Adriatic and Aegean seas. Thus, each sea basin has its own source of deep water. The threshold of the Strait of Tunis divides the Mediterranean Sea into two large deep basins. The temperature of the deep and bottom waters of the western basin is in the range of 12.6-12.7°, salinity - 38.4‰; east of the Strait of Tunis, the temperature rises to 13.1-13.3°, reaching 13.4° in the Levant Sea, and salinity remains very uniform - 38.7‰.

The significantly isolated Adriatic Sea is distinguished by its unique hydrological structure. Its shallow northern part is filled with surface Adriatic water, which is a product of mixing the waters of the Ionian Sea with coastal runoff. In summer, the temperature of this water mass is 22-24°, salinity is 32.2-38.4‰. In winter, with intense cooling and the development of convection, mixing occurs surface water with the transformed Levantine entering the sea and the formation of the deep Adriatic water mass. Deep water fills the basins of the Adriatic Sea and is characterized by uniform characteristics: temperature is in the range of 13.5-13.8°, salinity is 38.6-38.8‰. Through the Strait of Otranto, this water flows into the bottom layers of the central basin of the Mediterranean Sea and participates in the formation of deep waters.

Port Said

Fauna and environmental issues

The fauna of the Mediterranean Sea is characterized by a large species diversity, which is associated both with the long geological history of the sea and with environmental conditions. Fish are represented by 550 species, and about 70 of them are endemic: certain types of anchovy, gobies, stingrays, etc. Here you can find anchovy, sardine, mackerel, horse mackerel, flying fish, mullet, bonito, plume, etc. However, there are few large concentrations of fish, the number individual species small. The largest concentrations of fish form in winter, while in spring and summer, during fattening and spawning, they remain more scattered. Longfin and common tuna, sharks, and stingrays also live in the Mediterranean Sea. Longfin tuna is constantly present here, and common tuna, like many other fish species, migrates in the spring and summer to feed in the Black Sea.

One of the most productive areas of the Mediterranean Sea was its southeastern part, influenced by the river flow. Nile. Every year, a significant amount of nutrients and various suspended minerals entered the sea with the river waters. A sharp reduction in river flow and its intra-annual redistribution after the regulation of the Nile by the construction of the Aswan hydroelectric station in the early 60s. worsened the living conditions of all marine organisms and led to a decrease in their numbers. The decrease in the desalination zone and the flow of nutrient salts into the sea led to a decrease in the production of phyto- and zooplankton, the reproduction of fish stocks (mackerel, horse mackerel, sardine, etc.) decreased, and commercial catches decreased sharply. Due to increased economic activity, pollution of the Mediterranean Sea is progressively increasing, where the environmental situation has become threatening.

3. Characteristics of the oceanic aquatic environment.

The oceanic environment, that is, sea water, is not just a substance known to us from birth, which is hydrogen oxide H2O. Sea water is a solution of a wide variety of substances. Almost all known chemical elements are found in the waters of the World Ocean in the form of various compounds.

Most of all chlorides are dissolved in sea water (88.7%), among which sodium chloride predominates, that is, ordinary table salt NaCl. Sea water contains significantly less sulfates, that is, sulfuric acid salts (10.8%). All other substances account for only 0.5% of the total salt composition of seawater.

After sodium salts, magnesium salts are in second place in sea water. This metal is used in the manufacture of light and strong alloys needed in mechanical engineering, especially in aircraft construction. Each cubic meter of sea water contains 1.3 kilograms of magnesium. The technology for its extraction from sea water is based on the conversion of its soluble salts into insoluble compounds and their precipitation with lime. The cost of magnesium obtained directly from sea water turned out to be significantly lower than the cost of this metal, previously mined from ore materials, in particular dolomite.

It is worth noting that bromine, discovered in 1826 by the French chemist A. Balard, is not found in any mineral. Bromine can only be obtained from sea water, where it is contained in relatively small quantities - 65 grams per cubic meter. Bromine is used in medicine as a sedative, as well as in photography and petrochemistry.

Already at the end of the 20th century, the ocean began to provide 90% of the world's bromine and 60% of magnesium production. Sodium and chlorine are extracted from seawater in significant quantities. As for table salt, people have long received it from sea water by evaporation. Marine salt mines still operate in tropical countries, where salt is obtained directly from shallow areas of the coast, fencing them off from the sea with dams. The technology here is not very complicated. The concentration of table salt in water is higher than other salts, and therefore during evaporation it is the first to precipitate. The crystals that have settled at the bottom are removed from the so-called mother liquor and washed with fresh water to remove residual magnesium salts, which give the salt a bitter taste.

More advanced technology for extracting salt from sea water is used in numerous saltworks in France and Spain, which supply large volumes of salt not only to the European market. For example, one of the new ways to obtain salt is to install special seawater sprayers in saltworks pools. Water turned into dust (suspension) has a huge area of evaporation and from the smallest drops it evaporates instantly, and only salt falls on the ground.

The extraction of table salt from seawater will continue to increase, because deposits of rock salt, like other minerals, will sooner or later be depleted. Currently, about a quarter of all table salt needed by humanity is mined in the sea, the rest is mined in salt mines.

Sea water also contains iodine. But the process of obtaining iodine directly from water would be completely unprofitable. Therefore, iodine is obtained from dried brown algae that grows in the ocean.

Even gold is found in ocean water, although in tiny quantities - 0.00001 grams per cubic meter. There is a well-known attempt by German chemists in the 1930s to extract gold from the waters of the German Sea (as the North Sea is often called in German). However, it was not possible to fill the Reichsbank vaults with gold bars: production costs would exceed the cost of gold itself.

Some scientists suggest that in the next few decades it may become economically feasible to obtain heavy hydrogen (deuterium) from the sea, and then humanity will be provided with energy for millions of years to come... But uranium from sea water is already being mined on an industrial scale. Since 1986, the world's first plant for extracting uranium from sea water has been operating on the shores of the Inland Sea of Japan. The complex and expensive technology is designed to produce 10 kg of metal per year. To obtain such an amount of uranium, it is necessary to filter and subject to ion processing more than 13 million tons of sea water. But the Japanese, who are persistent in their work, get the job done. In addition, they are well aware of what atomic energy is. -)

An indicator of the amount of chemical substances dissolved in water is a special characteristic called salinity. Salinity is the mass of all salts contained in 1 kg of sea water, expressed in grams.. Salinity is measured in parts per thousand, or ppm (‰). On the surface of the open ocean, salinity fluctuations are small: from 32 to 38‰. The average surface salinity of the World Ocean is about 35‰ (more precisely, 34.73‰).

The waters of the Atlantic and Pacific Oceans have a salinity slightly above average (34.87‰), and the waters of the Indian Ocean are slightly lower (34.58‰). This is where the desalination effect of Antarctic ice comes into play. For comparison, we point out that the usual salinity of river waters does not exceed 0.15‰, which is 230 times less than the surface salinity of sea water.

The least saline waters in the open ocean are the waters of the polar regions of both hemispheres. This is explained by the melting of continental ice, especially in the Southern Hemisphere, and large volumes of river flows in the Northern Hemisphere.

Salinity increases towards the tropics. The highest concentration of salts is observed not at the equator, but in latitude bands 3°-20° south and north of the equator. These bands are sometimes called salinity belts.

The fact that the surface salinity of water in the equatorial zone is relatively low is explained by the fact that the equator is a zone of heavy tropical rains that desalinize the water. Often, near the equator, dense clouds cover the ocean from direct sunlight, which reduces water evaporation at such moments.

In marginal and especially inland seas, salinity differs from that of the ocean. For example, in the Red Sea, the surface salinity of water reaches the highest values in the World Ocean - up to 42‰. This is explained simply: the Red Sea is located in a zone of high evaporation, and it communicates with the ocean through the shallow and narrow Bab-el-Mandeb Strait, and does not receive fresh water from the continent, since not a single river flows into this sea, and rare rains unable to desalinate the water to any noticeable extent.

The Baltic Sea, extending far inland, communicates with the ocean through several small and narrow straits, is located in a temperate climate zone and receives the waters of many large rivers and small rivers. Therefore, the Baltic is one of the most desalinated basins of the World Ocean. The surface salinity of the central part of the Baltic Sea is only 6-8 ‰, and in the north, in the shallow Gulf of Bothnia, it even drops to 2-3 ‰).

Salinity changes with depth. This is explained by the movement of subsurface waters, that is, the hydrological regime of a particular basin. For example, in the equatorial latitudes of the Atlantic and Pacific oceans, below a depth of 100-150 m, layers of very saline waters (above 36 ‰) can be traced, which are formed due to the transfer of saltier tropical waters by deep countercurrents from the western margins of the oceans.

Salinity changes sharply only to depths of about 1500 m. Below this horizon, almost no fluctuations in salinity are observed. At greater depths of different oceans, salinity indicators converge. Seasonal changes in salinity on the surface of the open ocean are insignificant, no more than 1 ‰.

Experts consider a salinity anomaly to be the salinity of water in the Red Sea at a depth of about 2000 m, which reaches 300 ‰.

The main method for determining the salinity of sea water is the titration method. The essence of the method is that a certain amount of silver nitrate (AgNO 3) is added to the water sample, which, in combination with sodium chloride of sea water, precipitates in the form of silver chloride. Since the ratio of the amount of sodium chloride to other substances dissolved in water is constant, by weighing the precipitated silver chloride, you can quite simply calculate the salinity of the water.

There are other ways to determine salinity. Since, for example, indicators such as the refraction of light in water, the density and electrical conductivity of water depend on its salinity, then, having determined them, it is possible to measure the salinity of the water.

Taking samples of sea water to determine its salinity or other indicators is not an easy task. To do this, they use special samplers - bathometers, which allow taking samples from different depths or from different layers of water. This process requires a lot of attention and caution from hydrologists.

So, the main processes affecting the salinity of water are the rate of water evaporation, the intensity of mixing of more saline waters with less saline ones, as well as the frequency and intensity of precipitation. These processes are determined by the climatic conditions of a particular region of the World Ocean.

In addition to these processes, the salinity of sea water is influenced by the proximity of melting glaciers and the volume of fresh water brought by rivers.

In general, the percentage of various salts in sea water in all areas of the ocean almost always remains the same. However, in some places, marine organisms have a noticeable influence on the chemical composition of sea water. They use many substances dissolved in the sea for their nutrition and development, although in varying quantities. Some substances, such as phosphates and nitrogenous compounds, are consumed in particularly large quantities. In areas where there are many marine organisms, the content of these substances in the water decreases somewhat. A noticeable influence on the chemical processes occurring in sea water is exerted by the smallest organisms that make up the plankton. They drift along the surface of the sea or in the near-surface layers of water and, dying, slowly and continuously fall to the bottom of the ocean.

Salinity of the World Ocean. Current monitoring map(increase) .

What is it like general content salts in the World Ocean? Now answering this question is not at all difficult. If we assume that the total amount of water in the World Ocean is 1370 million cubic kilometers, and the average concentration of salts in sea water is 35‰, that is, 35 g in one liter, then it turns out that one cubic kilometer contains approximately 35 thousand tons salt. Then the amount of salt in the World Ocean will be expressed by the astronomical figure of 4.8 * 10 16 tons (that is, 48 quadrillion tons).

This means that even the active extraction of salts for domestic and industrial needs will not be able to change the composition of seawater. In this regard, the ocean, without exaggeration, can be considered inexhaustible.

Now we need to answer an equally important question: where does so much salt come from in the ocean?

For many years, science was dominated by the hypothesis that rivers brought salt to the sea. But this hypothesis, at first glance quite convincing, turned out to be scientifically untenable. It has been established that every second the rivers of our planet carry about a million tons of water into the ocean, and their annual flow is 37 thousand cubic kilometers. It takes 37 thousand years for the water in the World Ocean to be completely renewed - in about this time the ocean can be filled with river flow. And if we accept that in the geological history of the Earth there were at least one hundred thousand such periods, and the content of salts in river water in the average approximation is about 1 gram per liter, then it turns out that during the entire geological history of the Earth about 1. 4*10 20 tons of salts. And according to the scientists’ calculations, which we just cited, 4.8 * 10 16 tons of salt are dissolved in the World Ocean, that is, 3 thousand times less. But it's not only that. Chemical composition salts dissolved in river water differs sharply from the composition sea salt. If in sea water the compounds of sodium and magnesium with chlorine absolutely predominate (89% of the dry residue after evaporation of water and only 0.3% is calcium carbonate), then in river water calcium carbonate takes first place - over 60% of the dry residue, and sodium chlorides and magnesium together – only 5.2 percent.

Scientists are left with one assumption: the ocean became salty during its birth. The most ancient animals could not exist in weakly salted, much less freshwater, pools. This means that the composition of sea water has not changed since its inception. But where did the carbonates that came into the ocean along with river runoff for hundreds of millions of years go? The only correct answer to this question was given by the founder of biogeochemistry, the great Russian scientist Academician V.I. Vernadsky. He argued that almost all calcium carbonate, as well as silicon salts carried by rivers into the ocean, are immediately extracted from solution by those marine plants and animals that need these minerals for their skeletons, shells and shells. As these living organisms die, the calcium carbonate (CaCO 3) and silicon salts they contain are deposited on the seabed in the form of sediments organic origin. Thus, living organisms maintain the composition of its salts unchanged throughout the existence of the World Ocean.

And now a few words about another mineral contained in sea water. We have spent so many words praising the ocean for the fact that its waters contain many different salts and other substances, including deuterium, uranium and even gold. But we did not mention the main and main mineral that is found in the World Ocean - simple water H 2 O. Without this “mineral” there would be nothing on Earth at all: neither oceans, nor seas, nor you and me. About the main physical properties water, we already had the opportunity to talk. Therefore, here we will limit ourselves to only a few comments.

In the entire history of science, people have not unraveled all the secrets of this rather simple chemical substance, the molecule of which consists of three atoms: two hydrogen atoms and one oxygen atom. By the way, modern science claims that hydrogen atoms make up 93% of all atoms in the Universe.

And among the mysteries and secrets of water, there remain, for example, the following: why frozen water vapor turns into snowflakes, the shape of which is a surprisingly regular geometric figure, reminiscent of magnificent patterns. And the drawings on window panes on frosty days? Instead of amorphous snow and ice, we see ice crystals that are lined up like this amazingly that look like leaves and branches of some fairy-tale trees.

Or here's another one. Two gaseous substances- Oxygen and hydrogen combined together and turned into liquid. Many other substances, including solids, when combined with hydrogen, become gaseous, like hydrogen, for example, hydrogen sulfide H 2 S, hydrogen selenide (H 2 Se), or a compound with tellurium (H 2 Te).

It is known that water dissolves many substances well. They say that it dissolves, although to a vanishingly small degree, even the glass of the glass into which we poured it.

However, the most important thing to say about water is that water has become the cradle of life. Water, having initially dissolved dozens of chemical compounds in itself, that is, becoming sea water, turned into a solution unique in its diversity of components, which ultimately turned out to be a favorable environment for the emergence and maintenance of organic life.

In the first chapter of this story, we have already noted what is almost universally accepted. The hypothesis has now turned into a theory of the origin of life, each position of which, according to the authors of this theory, is based on factual data from cosmogony, astronomy, historical geology, mineralogy, energy, physics, chemistry, including biological chemistry and other sciences.

The first opinion that life originated in the ocean was expressed in 1893 by the German naturalist G. Bunge. He realized that the amazing similarity between blood and sea water in the composition of the salts dissolved in them was not accidental. Later, the theory of the oceanic origin of the mineral composition of blood was developed in detail by the English physiologist McKellum, who confirmed the correctness of this assumption by the results of numerous blood tests of various animals, from invertebrate mollusks to mammals.

It turned out that not only blood, but also the entire internal environment of our body shows traces preserved from the long stay of our distant ancestors in sea water.

Currently, world science has no doubts about the oceanic origin of life on Earth.

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