The waters of the White Sea are less desalinated due to freer communication with the ocean. In its basin, the salinity of surface waters is 24-26%o, in Gorlo 28-30%o, and in the bays it is much lower and fluctuates strongly under the influence of surge and tidal level fluctuations. Sometimes in the Dvina, Kandalaksha and Onega bays almost fresh water is replaced by water with a salinity of 20-25%o.[...]

The waters of inland seas located in tropical latitudes, where there is little precipitation, few rivers, and high evaporation, are more salinous than oceanic waters. These are the Mediterranean, Red and Persian Gulf seas. The Mediterranean Sea, characterized by a negative fresh balance and difficult water exchange with the ocean through the narrow Strait of Gibraltar, has a salinity of surface waters higher than that of the ocean. From the Strait of Gibraltar to Fr. In Sicily it is 37-38%o, in the eastern part of the sea it is 39%0 or more.[...]

The salinity of surface sea waters often differs significantly from the salinity of ocean waters (sometimes it exceeds it, sometimes it is less). These differences are determined by the conditions of water exchange between the seas and the ocean, the influence of climate and land runoff. The salinity of surface waters of seas, the water exchange of which occurs more or less freely, is close to oceanic. When water exchange is difficult, the differences can be significant.[...]

The salinity of the Ocean is not a constant value. It depends on climate (the ratio of precipitation and evaporation from the surface of the Ocean), the formation or melting of ice, sea currents, and near continents - on the influx of fresh river water. In the open Ocean, salinity ranges from 32-38%; in the marginal and Mediterranean seas its fluctuations are much greater. While experiencing fluctuations in the amount of dissolved salts, sea water is distinguished by the exceptional constancy of their ratio to each other. The ratio of dissolved substances is maintained in different parts of the Ocean, on its surface and in deep layers. Taking into account this regularity, a method was built for determining the salinity of sea waters by the amount of any one element contained in them, most often chlorine. [...]

The ocean is the main acceptor and accumulator of solar energy, since water has a high heat capacity. The water shell (hydrosphere) includes: the salty waters of the World Ocean and inland seas; fresh waters of land concentrated in mountain ice, rivers, lakes, swamps. Let's consider the environmental characteristics of the aquatic environment.[...]

The ocean belongs to the group of salty waters, while sea waters are sometimes brines (for example, the Red Sea) or semi-fresh (for example, the Sea of ​​Azov), that is, they have a sharply different concentration, less or more than the average, changing little in composition ocean water. The transition is sometimes quite abrupt.[...]

In the ocean, the difference in temperature and salinity is small, but the described process enhances the vertical mixing of water.[...]

The volume of water on the globe is measured at 1386 million km3, which means that each of us has 350 million m3 of water, which is equal to ten reservoirs such as Mozhaiskoe on the river. Moscow. Unfortunately, there is every reason for this. After all, a person needs not just any water, but only fresh water, that is, containing no more than 1 g of salts per 1 liter, and at the same time it must be of high quality. It is known that 97.5% of water is concentrated in the World Ocean, the salinity of which is 35%a, or 35 g/l. Fresh water accounts for only 2.5%, while more than 2/3 of it is conserved in glaciers and snowfields and only 0.32% is in lakes and rivers. The most important and used for a wide variety of needs, river waters make up only 0.0002% of the total water reserves [Lvovich, 1974].[...]

In the Pacific Ocean north of the subpolar front, North Pacific intermediate water is formed with a salinity of 33.6 to 34.6%o, which then spreads to the south at depths of 500-1500 m. [...]

In all oceans and seas there is a constant ratio of salts that make up the water. The total mass of salts in sea water is 48-1015 tons, or about 3.5% of the total mass of ocean water. This amount of salts would be enough to form a salt layer up to 45 m thick over the entire surface of our planet. For every 1000 g of ocean water there are 35 g of salts, i.e. The salinity of ocean water is on average 35%.[...]

The world's oceans are heterogeneous in both salinity and temperature. It is possible to distinguish isometric areas, layers and thinnest interlayers. The highest ocean water temperature (404°C) was recorded at a hot spring 480 km from the west coast of America. Water heated to such a temperature did not turn into steam, since the source was located at a considerable depth under conditions of high pressure. The cleanest water in the world is recorded in the Weddell Sea in Antarctica. Its transparency corresponds to the transparency of distilled water. At the same time, the waters of the World Ocean are in constant motion, their temperature and currents affect the state of air masses and determine weather and climatic conditions in adjacent territories.[...]

The area of ​​salt water (seas, oceans) is slightly more than 70% of the Earth's surface. Fresh waters (less than 1 g/l of salt) make up slightly less than 6% of the reserves or, in absolute terms, 90 million km3. But the trouble is that only about 3% of fresh water is easily accessible reserves such as rivers, lakes and reservoirs, the rest is glaciers and groundwater. Thus, we can only use about 2.5 million km3 of water. But some of this water is contaminated and unfit for consumption.[...]

The average salinity of water on the surface of different oceans is not the same: Atlantic 35.4%o, Pacific 34.9°/oo, Indian 34.8%o - Table. Figure 10 shows the average salinity on the surface of the oceans in the southern and northern hemispheres.[...]

The world ocean is the water shell of the Earth, with the exception of reservoirs on land and glaciers of Antarctica, Greenland, polar archipelagos and mountain peaks. The world's oceans are divided into four main parts - the Pacific, Atlantic, Indian, and Arctic oceans. The waters of the World Ocean, flowing into the land, form seas and bays. The seas are relatively isolated parts of the ocean (for example, the Black, Baltic, etc.), and the bays do not protrude into the land as much as the seas, and in terms of the properties of the waters they differ little from the World Ocean. In the seas, the salinity of water can be higher than the ocean (35%), as, for example, in the Red Sea - up to 40%, or lower, as in the Baltic Sea - from 3 to 20%. [...]

Typically, water contains various impurities of organic and inorganic origin. There is a distinction between salt and fresh water. The bulk of the water on our planet is salt water, forming the salty World Ocean and most of the mineralized underground waters of deep occurrence (1.5...2 km). [...]

Fronts in the ocean arise due to the influence of a variety of mechanisms. Sometimes they appear very clearly in the temperature and salinity fields, but are almost not expressed in the density field. Abrupt changes in properties at the fronts turn out to be significant due to the fact that they affect the dynamics. A review of satellite observations of temperature fronts was made in. The main climatic frontal zones (where fronts are most often recorded) in the North Pacific Ocean are shown in Fig. 13.11; they were discussed in Rodin's work. One of the important types of fronts is associated with Ekman convergence in the surface layer. Examples of such fronts are subtropical ones, which are observed at latitudes from 30° N. w. up to 40° south w. Their changes associated with fluctuations in Ekman divergence were studied in the work. The second type of fronts is formed at the boundary of water masses (see). Such a front separates, for example, the waters of subarctic and subtropical gyres. In the North Pacific Ocean (Fig. 13.11), this front is located at latitude 42° N. w. It is formed at the meeting point of the cold, equatorially directed Oyashio Current with the warm, polar-directed Kuroshio Current. On the surface, this front is well expressed in temperature and salinity sections, but in the density field it is weakly noticeable.[...]

In the World Ocean, physical, chemical, biological and other processes continuously occur that change salinity, i.e., decrease or increase the concentration of the solution. However, regardless of the absolute concentration of the solution, the quantitative relationships between the main ions remain constant. Therefore, it is enough to know the concentration of one of the components to determine the others. To determine salinity, the sum of Cl + Br + I ions, called chlorinity, is used, the concentration of which in sea water is the highest. [...]

The bulk of the water is concentrated in the World Ocean. Its average depth is more than 4000 m, it covers an area equal to 361 million km2 (71% of the world's surface), and is characterized by high salinity (3.5%). Continental bodies of water cover about 5% of the Earth's area. Of these, surface waters (lakes, rivers, swamps, etc.) account for a very small part (0.2%), glaciers - 1.7%. Groundwater makes up about 4% of the total volume of the hydrosphere. The entire planetary water reserve reaches 1450 million km.[...]

Sea water contains 89% chlorides, 10% sulfates and 0.2% carbonates, while fresh water contains 80% carbonates, 13% sulfates and 7% chlorides. The water of closed seas, such as the Caspian, is not typically seawater. It is significantly less salty and contains three times more carbonates than ocean water. According to modern concepts, the salinity of the water of the seas and oceans is “primary”, not changing during geological periods.[...]

Processes that change oceanological characteristics continuously occur in the World Ocean. As a result of uneven changes in these characteristics, horizontal and vertical gradients arise, simultaneously with which processes develop aimed at equalizing the properties of water masses and destroying gradients. These are processes of vertical and horizontal exchange, i.e. mixing. Changes in temperature, salinity and density with depth are associated with vertical gradients of these quantities. The gradient of each of these quantities can be positive or negative. If the density gradient is positive (density increases with depth), the water masses are in a stable state; if it is negative, they are unstable: light water tends to rise, and heavy water tends to sink. An increase in density under the influence of a decrease in temperature or an increase in salinity on the surface causes the upper layers of water to sink and the lower ones to rise. As a result, the density of water in the upper, mixed layer decreases, and in the underlying layer it increases. In the water layer located above the shock layer, water mixing processes occur most intensively; This layer is called the active layer. Below the jump layer, the waters become stable, since here the temperature decreases with depth, and salinity and density increase.[...]

Fluctuations in salinity over time are insignificant. Annual fluctuations in the open parts of the oceans do not exceed 1%o; at a depth of 1500-2000 m, salinity is almost unchanged (differences of 0.02-0.04%o). Significant fluctuations in salinity are observed in coastal areas, where the influx of fresh water is more intense in spring, as well as in polar regions due to the processes of freezing and melting of ice.[...]

Freshwater reserves account for less than 2% of water resources. The average salinity of the waters of the World Ocean is 3.5 g/l (in the oceans there are 48-1015 tons of table salt), drinking water should contain no more than 0.5 g/l, plants die from water containing 2.5 g/l of salt. Approximately 3/4 of the world's fresh water reserves are located in the ice of Antarctica, the Arctic, and glacial mountains. About 35 thousand sea ice and icebergs are included in the volume of the World Ocean. But 10-15 thousand icebergs break off annually from the Arctic and Greenland coasts alone. The annual river flow is estimated at 41 thousand km’. Europe and Asia, where 70% of the population lives, contain only 39% of the world's river water reserves. Lake Baikal, the world's most abundant lake (23 thousand km3), contains 20% of the world's surface fresh water reserves. Russia is home to the world's largest underground water storage facility - the West Siberian artesian basin with an area of ​​3 million km2, which is almost 8 times the area of ​​the Baltic Sea.[...]

If the density of sea water is constant, then the ocean is called homogeneous. If the vertical distribution of density depends only on pressure, then we speak of a barotropic ocean. If the density of sea water is determined by temperature, salinity and pressure, then the ocean is considered baroclinic.[...]

For every 1000 g of ocean water there are 35 g of salts, i.e. The salinity of ocean water is on average 35%o (ppm).[...]

According to modern concepts, the salinity of the water of the seas and oceans is “primary”, not changing during geological periods. Thus, the question of how water appeared on Earth requires study and clarification.[...]

Being an excellent solvent, water contains dissolved salts, gases, and organic substances, the content of which in water can vary over a wide range. If the salt concentration is less than 1 g/kg, the water is considered fresh; if the salt concentration is up to 25 g/kg, it is considered brackish; and if the concentration is higher, it is considered salty. In the ocean, the salt concentration is about 35 g/kg, in fresh lakes and rivers it is 5-1000 mg/kg. Sea water is a multicomponent system, including water molecules, anions and cations of salts, as well as many impurities. Good mixing of sea waters leads to equalization of the content of salt components in different parts of the World Ocean, and therefore we can talk about the constancy of the salt composition of ocean waters. To characterize salinity, the value S is used - salinity, which determines in grams the mass of dissolved solids contained in 1 kg of sea water, provided that bromine and iodine are replaced by an equivalent chlorine content, all carbon dioxide salts are converted to oxides, all organic substances are burned at a temperature of 480 ° WITH. This definition of salinity goes back to the previously accepted definition of salinity by chlorine content by titrating sea water. Salinity is measured in parts per thousand - ppm (%o). The constancy of the salt composition of sea water makes it possible to determine salinity by the content of one component.[...]

Similar expressions can be written for the salinity and density of sea water. The first term on the right side is the class of phenomena that form the subject of classical oceanography; the second term - heterogeneities related to the phenomenon of fine thermohaline structure; the third term is Reynolds microturbulence; ¿ig - values ​​of spatial and temporal scales delimiting the structural elements of water masses, caused by a thin layered structure and turbulence. As a rule, the ruggedness of vertical salinity profiles is greater than the ruggedness of temperature distributions. Sea water has another interesting property. If in the atmosphere the rates of molecular diffusion of heat and moisture are almost the same, then the rates of diffusion of heat and salt in the ocean differ by two orders of magnitude (K = 1.4 10 3 cm2/s, 1 = 1.04 10 5 cm2/s), which leads to such a phenomenon as differential diffusion convection, which is one of the mechanisms responsible for the formation of the fine thermohaline structure of sea waters.[...]

Since information about the temperature and salinity fields makes it possible to calculate currents only relative to a certain given level, the velocities of stationary geostrophic currents in the ocean cannot be determined absolutely accurately. Therefore, it is also impossible to find the exact values ​​of the transfers and compare them with calculations using the Sverdrup relation. However, some comparisons can still be made. So, for example, in Fig. 12.7,6 shows the currents of the North Atlantic at a depth of 100 m relative to the currents at a depth of 1500 m. If we assume that the latter currents are relatively weak, then Fig. 12.7,6 can be considered as a picture of near-surface geostrophic currents. On it you can find many striking coincidences with Fig. 12.7a, which indicates that the effect of wind largely explains the surface circulation pattern. On the other hand, the significant differences that can also be seen in these figures indicate the importance of other factors, such as buoyancy forces. Worthington's calculations, in particular, show that the subsidence of water in the Greenland Sea carries large masses of surface water from the North Atlantic there, and this significantly affects the overall circulation pattern.[...]

The uneven distribution of temperature, as well as salinity, is mainly created by mixing processes and sea currents. In the surface layers, within the active layer of the sea, the interlayering of water masses is associated mainly with processes of vertical exchange, and at depth, the heterogeneity of oceanological characteristics is associated with the general circulation of waters of the World Ocean. The heterogeneity of the waters of the oceans and seas, associated with the processes of vertical and horizontal exchange, determines the presence of intermediate cold or warm layers with low or high temperatures. These layers can be of convective (due to mixing) and advective origin. The latter are associated with the delivery (askes), i.e. horizontal invasion, of water masses transported from outside by currents. An example is the presence of warm Atlantic waters throughout the central part of the Arctic Ocean, which can be traced at depths from 150-250 to 800-900 m. During the transition from surface waters to intermediate, deep and shallow waters (see p. 165) at their boundaries Do I have any contact? vertical gradients of oceanological characteristics. The transition layer, in which there are large gradients of temperature, salinity, density and other properties, is called the jump layer. These layers can be temporary, seasonal or permanent in the active layer and at its border with the waters of the depths. Deep-sea observations in various areas of the World Ocean (Fig. 14) show that in open areas, except for the polar regions, the temperature changes noticeably from the surface to a depth of 300-400 m, then up to 1500 m the changes are very insignificant, and from 1500 m it hardly changes. At 400-450 m the temperature is 10-12 ° C, at 1000 m 4-7 ° C, at 2000 m 2.5-4 ° C and from a depth of 3000 m it is about 1-2 ° C. [...]

If you do not touch dirty drains and toxic drains, then waters have been divided into salty and fresh since ancient times. Salt waters, compared to fresh waters, contain an increased concentration of salts, primarily sodium. They are not suitable for drinking and industrial use, but are excellent for swimming and water transport. The salt composition of salty waters in different bodies of water varies quite a lot: for example, in the shallow Gulf of Finland the waters are less salty than in the Black Sea, and in the oceans the salinity is much higher. I would like to remind you that salt water is not necessarily sea water. There are known basins with exclusively salty waters that have no communication with the sea, such as the Dead Sea in Palestine and the salt lake Baskunchak.[...]

Ripe lagenaria fruits are so light that they do not sink in salt water and are able to float in the ocean for a long time without damage and without the seeds losing their viability. Since ancient times, accidentally falling into the Atlantic Ocean, the fruits of lagenaria, picked up by ocean currents, sailed from the shores of West Africa to Brazil or across the Pacific Ocean from Southeast Asia to Peru, and from there the ancient inhabitants of South and North America spread throughout the continent .[...]

All of these factors determine the regime and changes in the salinity of the waters of the oceans and seas. Since salinity is the most conservative, established property of the waters of the World Ocean, we can talk about the balance of salts. The incoming part of the salt balance is composed of the influx of salts: a) with continental runoff, b) with precipitation, c) from the Earth's cedar in the form of products of mantle degassing, d) during the dissolution of rocks at the bottom of oceans and seas.[...]

The hydrosphere is the water shell of the Earth, including oceans, seas, rivers, lakes, groundwater and glaciers, snow cover, as well as water vapor in the atmosphere. The Earth's hydrosphere is 94% represented by salty waters of the oceans and seas, more than 75% of all fresh water is conserved in the polar caps of the Arctic and Antarctica (Table 6.1).[...]

The salinity of the water of the World Ocean is 35 g/l, and at a salinity of 60 g/l the main part of the cells cannot exist. The transport of salts by rivers into the ocean would double the concentration of salts every 80 million years, if not for natural processes that remove salts from ocean water. Under these conditions, the relative stability of ocean salinity has been maintained for several hundred million years.[...]

Biochemical properties. All biochemical processes of decomposition of organic matter in wastewater in seas and oceans proceed much more slowly compared to freshwater basins. This occurs due to the fact that the concentration of salts in salt water is greater than in fresh water and therefore the osmotic pressure through which the microbial cell absorbs the nutrients necessary for its life decreases (Gaultier, 1954). Accordingly, the decrease in the BOD value in sea water during the process of its self-purification occurs much more slowly than in fresh water. [...]

Temperate and tropical land zones with their humid climate and developed biostrome continue on the ocean as belts with high biological productivity. Subtropical desert belts of land with a poorly developed biostrome can be equally traced over the ocean. Ultimately, the lack of moisture both on land and in the ocean leads to a similar result for the bios - deserts appear, almost devoid of life”2.[...]

The small volume of work, of course, could not accommodate the enormous information that is associated with the problem of water desalination. But we tried to show that the idea of ​​​​obtaining fresh water from the colossal volume of salty waters of the seas and oceans occupied the minds of ancient thinkers and has now acquired real forms of not only technological, but also technical solutions. Today, entire cities have grown up on sun-scorched, waterless land thanks to the discovery of ways to desalinate seawater on an industrial scale.[...]

Regarding this project, M. Ewing’s forecast about the consequences of the implementation of the dam construction is known. According to this forecast, the cessation of the flow of saltier waters into the Atlantic Ocean could, within three decades, lead to such a decrease in salinity in it that it would entail a complete change in the circulation of ocean waters, which could ultimately result in the cessation of the flow of warm Gulf Stream waters into the Arctic and cooling there with simultaneous warming in continental Europe. At one time, this forecast caused a negative reaction from another famous oceanologist G. Stommel, who pointed out that based on M. Ewing’s assumptions, reverse processes could be predicted with equal success. This example is given in order to show the complexity and ambiguity of such forecasts in the current state of ocean science, even for stationary processes of exchange of water masses. [...]

Various water masses are separated by frontal zones or frontal surfaces, in which the gradients of the characteristics of water masses become sharper. Quasi-stationary climatic frontal zones are the natural boundaries of the main water masses in the ocean. There are five types of fronts in the open ocean: equatorial, subequatorial, tropical, subpolar, polar. The frontal zones are distinguished by the high dynamism of the processes occurring in them. In the coastal zone, in the estuary zone, fronts are formed that separate shelf or drainage waters from the waters of the deep-sea part. The formation of one type of front or another depends on external conditions. According to the data of subsurface towing of temperature and salinity probes (measurements were carried out at a depth of 30 cm), with a front width of about 70 m, the salinity and temperature gradients are 2.2%o and 1.1° per 10 m, respectively. A runoff front with a lens of desalinated waters is formed at the flow of fresh river water over salty and dense sea water. In the case of the influx of Baltic waters into the lagoon, a front of intrusion of heavy sea waters into the lighter waters of the lagoon is formed. When a wedge of salty sea waters propagates along a deep sea channel, a typical estuarine front is observed. Typical changes in temperature, salinity and density as a front crosses are shown in Fig. 6.5.[...]

This type of renewable energy resource is perhaps the most exotic, and the youngest in terms of development time: the first technical ideas date back only to the 70s. of our century. The renewal of this type of resource is associated with the transformation of part of the thermal energy of the ocean during the evaporation of water from its surface. As already noted, about 54% of the total balance of energy coming from the Sun is spent on this. When fresh water enters in the form of precipitation and river runoff back into the ocean, in the process of mixing with salt water, energy is released that is practically proportional to the change in entropy of the fresh-ocean water system, which is a measure of the orderliness of this system. The change in entropy itself is an unobservable phenomenon, therefore, for example, at river mouths there are no noticeable manifestations of the release of additional energy. The energy of dissolution can be determined by first finding the value of the equilibrium osmotic pressure that occurs on a thin film that separates fresh and ocean water and has the ability to pass only water molecules. The penetration of HgO molecules continues until the pressure of the solution column balances the osmotic pressure, as a result of which equilibrium conditions are established between the solution and the solvent.[...]

Currently, work on organizing irrigated agriculture for growing perennial herbs and vegetables in the steppe zone continues, but small irrigated fields with an area of ​​tens (not more than 200-300) hectares are being created, water is drawn from artificial reservoirs in which spring snow waters accumulate. Irrigation from lakes is prohibited, where interference with the hydrological regime is especially dangerous, as it can lead to irreversible changes in their ecosystems (for example, the disappearance of fish and water blooms, i.e., the massive development of cyanobacteria, etc.). HYDROSPHERE (G.) - the water shell of the Earth, including oceans, seas, rivers, lakes, groundwater, glaciers. The structure of the Earth is shown in table. 16. 94% of the world is represented by salty waters of the oceans and seas, and the contribution of rivers to the planet’s water budget is 10 times less than the amount of water vapor in the atmosphere.[...]

Only the uppermost layers, 100-200 m thick, can be called true pelagic: in some places, foraminifera and pteropods make up more than 50% of them, while siliceous microfossils are rare. The increased salinity of the waters of the Red Sea probably prevents the development of radiolarians, and the appearance of these microorganisms in the Quaternary sediments corresponds to interglacial eras of high sea level, when the restriction of water exchange with the ocean was minimal. Coccoli-tophorites can withstand harsher conditions, but during the last glacial maximum, salinity was so high that even the most tolerant forms eventually disappeared.

Seventy percent of our planet's surface is covered with water - most of it in the oceans. The waters of the World Ocean are heterogeneous in composition and have a bitter-salty taste. Not every parent can answer the child’s question: “Why does sea water taste like that?” What determines the amount of salt? There are different points of view on this matter.

In contact with

What determines the salinity of water?

At different times of the year in different parts of the hydrosphere, salinity is not the same. Several factors influence its change:

• ice formation;
• evaporation;
• precipitation;
• currents;
• river flow;
• melting ice.

While water evaporates from the surface of the ocean, the salt does not erode and remains. Its concentration increases. The freezing process has a similar effect. Glaciers contain the largest supply of fresh water on the planet. The salinity of the World Ocean increases during their formation.

The opposite effect is characterized by the melting of glaciers, during which the salt content decreases. The source of salt is also rivers flowing into the ocean and atmospheric precipitation. The closer to the bottom, the less salinity. Cold currents reduce salinity, warm currents increase it.

Location

According to experts, The concentration of salt in the seas depends on their location. Closer to the northern regions the concentration increases, to the south it decreases. However, in the oceans the salt concentration is always greater than in the seas, and location has no effect on this. There is no explanation for this fact.

Salinity is determined by the presence in it magnesium and sodium. One of the options for explaining the different concentrations is the presence of certain land areas enriched with deposits of such components. However, such an explanation is not very plausible if we take into account sea currents. Thanks to them, over time, the salt level should stabilize throughout the entire volume.

World Ocean

Ocean salinity depends on geographic latitude, proximity of rivers, and climatic features of objects etc. Its average value according to measurement is 35 ppm.

Near the Antarctic and Arctic in cold areas the concentration is lower, but in winter, during the formation of ice, the amount of salt increases. Therefore, the water in the Arctic Ocean is the least salty, and in the Indian Ocean the concentration of salt is the highest.

The Atlantic and Pacific oceans have approximately the same salt concentration, which decreases in the equatorial zone and, conversely, increases in tropical and subtropical regions. Some cold and warm currents balance each other. For example, the salty Labrador Current and the unsalted Gulf Stream.

Interesting to know: How many exist on Earth?

Why are the oceans salty?

There are different points of view that reveal the essence of salt in the ocean. Scientists believe that the reason is the ability of water masses to destroy rock, leaching easily soluble elements from it. This process is ongoing. Salt saturates the seas and gives them a bitter taste.

However, there is also a diametrically opposite opinion on this issue:

Volcanic activity decreased over time and the atmosphere cleared of vapors. Acid rain fell less and less, and about 500 years ago the composition of the ocean water surface stabilized and became what we know it today. Carbonates, which enter the ocean with river water, are an excellent building material for marine organisms.

The main feature that distinguishes the waters of the World Ocean from the waters of land is their high salinity.

The number of grams of substances dissolved in 1 liter of water is called salinity . Sea water is a solution of 44 chemical elements, but the main role in it is played by salts, chlorides (89%) and sulfates (10%). Sea water is a relatively homogeneous solution of various salts, completely ionized, 99% of the total salts are sodium, magnesium, potassium, calcium, chlorine and sulfur ions. In addition, it also contains suspended particles, dissolved gases, and some organic compounds. Table salt gives water a salty taste, while magnesium salt gives it a bitter taste.

Salinity is expressed in ppm (Latin pro mille - “per thousand”). This term means one thousandth of any value. Permille is denoted o/oo. The average salinity of sea water in the ocean is 35 o/oo, which means that 35 grams of substance are dissolved in a liter of sea water. Fluctuations in salinity depend on many factors:

From water evaporation. During this process, the salts do not evaporate;

From ice formation;

From precipitation;

From river water flow, especially for inland seas;

From melting ice.

Melting ice, precipitation, river runoff - all this has a desalination effect on sea water, and evaporation and ice formation, on the contrary, contribute to an increase in salinity. Evaporation and precipitation play a major role in changing salinity, so the salinity of surface waters is very dependent on climatic conditions associated with latitude (see “Water Masses”).

In equatorial regions ocean salinity approx. 34 o/oo, since here the surface is strongly heated by the Sun, ascending air currents are formed, a low pressure area is formed and an abundance of precipitation falls.

In tropical waters, where an area of ​​high pressure is formed, downward air currents do not contribute to precipitation and there are few rivers, the salinity is 36 o/oo.

In polar latitudes, where melting ice has a strong desalinating effect, the salinity is 32 o/oo.

Rivers also have a desalination effect, so the salinity of ocean waters off the continents significantly less than in the center of the ocean, since river waters desalinate coastal waters.

The saltiest is Red sea - 42 o/oo, This is because this inland sea is spreading in tropical latitudes, Where few rivers, falls out little precipitation, evaporation of water from strong heating by the Sun is very large.

The salinity of another Inland Sea - the Baltic - is significantly lower - 11 o/oo(in the center - 6 o / oo, in the eastern part of the Gulf of Finland up to 1 o / oo. This is explained by the fact that this sea is located in a climate zone where precipitation falls, and flows into it many rivers.

Sometimes the overall picture of the salinity of the World Ocean is disrupted currents , which is clearly visible in the example Gulf Stream- one of the most powerful currents in the ocean, the branches of which can penetrate far into the Arctic Ocean. At the same time, the salinity of the current waters is significantly higher than the salinity of ocean waters.

The opposite phenomenon is observed off the coast of North America, where the cold Labrador the current, moving from the polar latitudes, contributes to a decrease in salinity off the coast of the continent.

The salinity of the deep layers of the World Ocean is generally almost constant. Waters whose salinity does not exceed 1 o/oo are called fresh .

Ocean water temperature

The ocean receives a lot of heat from the Sun - occupying a large area, it receives more heat than land. Water has high heat capacity, so a huge amount of heat accumulates in the ocean. Only the top 10-meter layer of ocean water contains more heat than the entire atmosphere. But the sun's rays heat only the top layer of water; heat is transferred down from this layer as a result of constant stirring the water. But it should be noted that the water temperature decreases with depth, first abruptly, and then smoothly. At depth, water is almost uniform in temperature, since the depths of the oceans are mainly filled with waters of the same origin, forming in the polar regions of the Earth. At a depth more than 3-4 thousand meters the temperature usually ranges from +2°C to 0°C.

The temperature of the world's oceans depends on latitude and distributed on its surface zonally. The highest average temperatures are located at the equator and are 27°-28°C. Since our Earth is a globe, with increasing latitude the angle of incidence of the sun's ray decreases, the amount of solar radiation decreases and the temperature of the waters of the World Ocean decreases. Due to the proximity of cold Antarctica, the rate of temperature decrease in the south is slightly faster than in the north.

The temperature of sea water is also affected by climate of surrounding areas: for example, the temperature of the waters of the Red Sea, surrounded by hot deserts, reaches 34°C.

The temperature of sea water in temperate latitudes is greatly influenced by season and even Times of Day.

The temperature of ocean waters is strongly influenced by ocean currents: Warm currents carry water from the equator to temperate latitudes, and cold currents carry water from the polar regions. Such mixing of waters contributes to a more uniform distribution of temperatures in water masses.

For the entire oceans average surface layer temperature ocean waters is +17.5°C. It decreases with depth, however, the temperature of the waters of hot springs at the bottom of the ocean reaches 400°C. The average temperature of the entire mass of ocean waters is only 4°C. The highest average temperature at the surface of the water in the Pacific Ocean is 19°C, in the Indian Ocean - 17°C, in the Atlantic Ocean - 16°C, in the Arctic Ocean - 1°C.

So, the ocean absorbs 25-50% more heat than land. The sun heats the water all summer, and in winter this heat enters the atmosphere, so without the World Ocean, such severe frosts would occur on Earth that all life on the planet would die. This is its huge role for living beings of the Earth. It has been calculated that if the oceans did not conserve heat so carefully, the average temperature on our planet would be -21°C, which is 36° lower than what we have now.

Ice in the ocean

The freezing point of water with average salinity is 1.8°C below 0°. The higher the salinity of the water, the lower its freezing point. Ice formation in the ocean begins with the formation of freshwater crystals, which then freeze together. Between the crystals are droplets of salty water, which gradually drains, so young ice is saltier than old, desalinated ice. The thickness of first-year ice reaches 2-2.5 m, and multi-year ice has a thickness of up to 5 m.

Ice forms only in arctic and subarctic latitudes, where winters are long and very cold.

By origin, the ice found in the seas and oceans is not only marine, that is, formed by the freezing of salt water; fresh ice is carried by rivers and enters the ocean from continents and islands. Continental ice floating mountains often form in the ocean - icebergs . These are giant ice mountains of various shapes. They broke away from the glaciers covering the continent. Northern icebergs are separated from Greenland ice sheet , which annually releases more than 300 km 2 ice. Northern icebergs are smaller in size than southern ones, which are formed by breaking off ice blocks from covers of Antarctica . Most often, northern icebergs are 1-2 km long, but there are also those that reach 200 and even 300 km in length and more than 70 km in width. The height of individual ice mountains together with the underwater part can reach 600 m.

The cruising range of icebergs and the duration of their existence depend not only on the speed and direction of sea currents, but also on the properties of the iceberg itself. Very large and deeply frozen Antarctic icebergs exist for many years, and sometimes for more than a decade. Greenland icebergs melt faster, their lifespan is only 2-3 years. They are smaller and their freezing temperature is lower. Northern and southern icebergs differ from each other in their shape. Greenland icebergs are dome-shaped, sometimes pyramid-shaped, ice mountains. Antarctic icebergs most often have a flat surface and vertical vertical walls.

Icebergs are carried by sea currents to lower latitudes, where they gradually melt. For example, in the Atlantic Ocean, the remains of these ice mountains are sometimes found at the latitude of Bermuda and the Azores (30°-40° N). Sometimes icebergs end up in areas of heavy shipping, and they pose a threat here, since, firstly, the ice reflects sunlight, cools the air and contributes to the formation of fog, and secondly, most of the iceberg is under water, and ship collisions are most often happening to this part of the ice mountain. Thus, in 1912, the sinking of the steamship Titanic occurred as a result of its collision with an iceberg. To prevent this disaster, iceberg warning devices are now installed on ships.

But there may be icebergs source of fresh water , the lack of which is increasingly felt on the planet. Projects are already being developed to use icebergs to supply fresh water to the coastal areas of Australia, South America, Asia, and Africa. The initiator of the first conference discussing the problem of “catching” and towing icebergs as a source of fresh water was the king of Saudi Arabia, a state located in the desert.

In 1773, the first report appeared in print about the so-called “black icebergs” discovered off the coast of Antarctica. New Zealand scientists have suggested that the black color of these ice mountains is caused by the activity of volcanoes in the South Shetland Islands. The glaciers on these islands are covered with a layer of volcanic dust, which is not washed off by sea water.

Ice covers about 15% of the entire water area of ​​the World Ocean, that is, 55 million km 2, including 38 million km 2 in the Southern Hemisphere. Ice cover has a major impact on ocean life and the Earth's climate.

3. Characteristics of the oceanic aquatic environment.

© Vladimir Kalanov,
"Knowledge is power".

The oceanic environment, that is, sea water, is not just a substance known to us from birth, which is hydrogen oxide H 2 O. 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 seawater 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 the total salt content 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. The chemical composition of salts dissolved in river water differs sharply from the composition of 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 organic sediments. Thus, living organisms throughout the existence of the World Ocean maintain the composition of its salts unchanged.

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. We have already had the opportunity to talk about the basic physical properties of water. 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 fairly 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. What about drawings on window glass on frosty days? Instead of amorphous snow and ice, we see ice crystals, which are lined up in such an amazing way that they look like the 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.

© Vladimir Kalanov,
"Knowledge is power"

Our planet is covered with water by 70%, of which more than 96% is occupied by oceans. This means that most of the water on Earth is salty. What is water salinity? How is it determined and what does it depend on? Is it possible to use such water on the farm? Let's try to answer these questions.

What is water salinity?

Most of the water on the planet has salinity. It is usually called sea water and is found in oceans, seas and some lakes. The rest is fresh, its amount on Earth is less than 4%. Before you understand what the salinity of water is, you need to understand what salt is.

Salts are complex substances that consist of cations (positively charged ions) of metals and anions (negatively charged ions) of acid bases. Lomonosov defined them as “fragile bodies that can dissolve in water.” There are many substances dissolved in sea water. It contains sulfates, nitrates, phosphates, cations of sodium, magnesium, rubidium, potassium, etc. Together these substances are defined as salts.

So what is water salinity? This is the content of substances dissolved in it. It is measured in parts per thousand - ppm, which are designated by a special symbol - %o. Permille determines the number of grams in one kilogram of water.

What determines the salinity of water?

In different parts of the hydrosphere and even at different times of the year, the salinity of water is not the same. It changes under the influence of several factors:

• evaporation;
• ice formation;
• precipitation;
• melting ice;
• river flow;
• currents.

When water evaporates from the surface of the oceans, salts remain and do not erode. As a result, their concentration increases. The freezing process has a similar effect. Glaciers contain the largest reserve of fresh water on the planet. During their formation, the salinity of the waters of the World Ocean increases.

The melting of glaciers has the opposite effect, reducing the salt content. In addition to them, the source of fresh water is precipitation and rivers flowing into the ocean. The level of salts also depends on the depth and nature of the currents.

Their greatest concentration is on the surface. The closer to the bottom, the less salinity. influence the salt content in a positive direction; cold ones, on the contrary, reduce it.

Salinity of the World Ocean

What is the salinity of sea water? We already know that it is far from the same in different parts of the planet. Its indicators depend on geographic latitudes, climatic features of the area, proximity to river objects, etc.

The average salinity of the waters of the World Ocean is 35 ppm. Cold areas near the Arctic and Antarctic are characterized by lower concentrations of substances. Although in winter, when ice forms, the amount of salts increases.

For the same reason, the least saline ocean is the Arctic Ocean (32%). The Indian Ocean has the highest content. It covers the Red Sea and Persian Gulf region, as well as the southern tropical zone, where salinity is up to 36 ppm.

The Pacific and Atlantic oceans have approximately equal concentrations of substances. Their salinity decreases in the equatorial zone and increases in subtropical and tropical regions. Some are warm and balance each other out. For example, the non-salty Gulf Stream and the salty Labrador Current in the Atlantic Ocean.

Salinity of lakes and seas

Most lakes on the planet are fresh, as they are fed mainly by sediments. This does not mean that there are no salts in them at all, just that their content is extremely low. If the amount of dissolved substances exceeds one ppm, then the lake is considered saline or mineral. The Caspian Sea has a record value (13%). The largest fresh lake is Baikal.

The concentration of salts depends on how the water leaves the lake. Fresh water bodies are flowing, while saltier ones are closed and subject to evaporation. The determining factor is also the rocks on which the lakes were formed. Thus, in the region of the Canadian Shield, rocks are poorly soluble in water, which is why the reservoirs there are “clean”.

The seas are connected to the oceans through straits. Their salinity is slightly different and affects the average values ​​of ocean waters. Thus, the concentration of substances in the Mediterranean Sea is 39% and is reflected in the Atlantic. The Red Sea, with an indicator of 41%o, greatly raises the average. The saltiest is the Dead Sea, in which the concentration of substances ranges from 300 to 350%o.

Properties and significance of sea water

Not suitable for economic activity. It is not suitable for drinking or watering plants. However, many organisms have long adapted to life in it. Moreover, they are very sensitive to changes in its salinity level. Based on this, organisms are divided into freshwater and marine.

Thus, many animals and plants that live in the oceans cannot live in the fresh water of rivers and lakes. Edible mussels, crabs, jellyfish, dolphins, whales, sharks and other animals are exclusively marine.

People use fresh water for drinking. Salted water is used for medicinal purposes. Water with sea salt is consumed in small quantities to restore the body. The healing effect comes from swimming and bathing in sea water.