We will answer the following questions.
1. What is called the salinity of sea water?
Sea water is a special type of natural water. The most important characteristic of sea water is salinity - the amount of salts dissolved in 1 liter of water. The salinity unit is ppm (means 1/1000 of a number and is indicated by the sign ‰). The average salinity of the waters of the World Ocean is 35 ‰. This means that 35 g of salts are dissolved in 1 liter of sea water.
2. What is the salinity of different parts of the oceans?
In those areas of the World Ocean where heavy precipitation falls, large rivers flow, ice melts, and the salinity of the waters decreases. The minimum salinity (2 ‰) is noted in the Gulf of Bothnia Baltic Sea. Increased evaporation of water from the surface of the ocean with a small amount of precipitation leads to an increase in salinity. The waters of the Red Sea have the highest salinity: on the surface 42 ‰, and at some points near the bottom - more than 280 ‰ (Fig. 90). The taste of sea water is bitter-salty. This is due to the composition of dissolved salts. The salty taste of sea water is given by table salt, the bitter taste is given by magnesium salts. If all the salts dissolved in the waters of the World Ocean are evaporated and evenly distributed over the surface of the Earth, then our planet will be covered with a layer of salt 45 cm thick.
3. At what temperature does sea water freeze?
Sea water does not have a specific freezing point. The temperature at which ice crystals begin to form depends on salinity: the higher the salinity, the lower the freezing point. At a salinity of 35 ‰, the freezing point of sea water is -1.9 °C. Density sea ice less than the density of sea water. Therefore, floating ice rises above the surface of the water by 1/7-1/10 of its thickness (Fig. 92).
4. How does the temperature of water in the oceans change?
The unique property of water as a substance is its ability to heat up slowly and cool down slowly. Therefore, the ocean accumulates a huge amount of heat and serves as a temperature regulator for surface air layers.
The surface temperature of the waters depends on the amount of solar heat and varies significantly in different latitudes (Fig. 91) Temperature surface water tropical zone reaches 27 - 29 ° C. As we move towards the polar regions, the temperature of surface waters decreases, reaching negative values: from -1.5 to -1.7 ° C in the Arctic Ocean and the seas surrounding Antarctica.
When diving into the depths of the ocean, a decrease in water temperature is observed everywhere (exceptions are the polar regions). In the upper layer of water, already at a depth of 300 - 500 m, the temperature drops sharply. Below, the water temperature decreases gradually. At depths of more than 3000 - 4000 m, the water temperature fluctuates between +2 and -1°C.
5. Why are currents formed in the oceans?
The waters of the oceans are constantly in motion: ocean water moves both vertically and horizontally.
The wind, due to the force of friction and pressure, causes oscillatory movements of surface water. This is how wind waves appear (up to 25 m in height) (Fig. 94, 95).
Surface water can travel great distances. In the ocean there is a whole system of peculiar "rivers without banks" - currents that are born for various reasons. The main reason for the formation of currents is constant winds that affect the sea surface. Surface waters begin to move in the direction of the wind - this is how wind (drift) currents are formed. They carry huge masses of water.
6. Which currents are called warm and which are cold?
Currents can be warm or cold. The water temperature of the warm currents is higher than in the surrounding waters. The water of cold currents has a lower temperature than the surrounding waters. Warm currents form near the equator, where the Sun heats the water more. The amount of solar heat in the direction from the equator to the poles decreases, therefore, currents directed towards the poles are warm, and currents directed towards the equator are cold.
Surface currents on the map are shown by arrows of two colors. On maps, blue arrows indicate cold currents, and red arrows indicate warm currents.
The role of currents in the life of the ocean is enormous. They carry heat, food for living organisms, are the ways of movement of fish and marine animals.
7. What are the reasons for the formation of ebbs and flows?
The Moon and the Sun, by the force of their attraction, cause tidal phenomena on the Earth. The tidal wave causes the water level in the ocean to rise. The highest water level at high tide is called high water. At low tide, the water level drops, the lowest water level at low tide is called low tide. The height of the tide corresponds to the difference in the levels of high water and low water and is determined by the relative position of the Earth, Moon and Sun. The main features of the tide are determined by the Moon, because. the lunar force acts 2.5 times stronger than the solar one. In addition, the height of the tide depends on geographical location, depth of the sea and the shape of the coastline.
We will learn how to plan a text describing the ocean and describe the ocean according to the plan, draw up a map with the “route of the global ocean conveyor”.
1. Salinity of sea water
Fill in the missing words.
Salinity of sea water is the amount of salts in water dissolved in 1 liter (1000 g) of water.
The average salinity of the oceans is 35%.
The main salts of sea water are table salt and magnesium salt.
How many grams of sea salt must be dissolved in a liter of fresh water to obtain sea water with a salinity equal to that of the oceans?
Table 1
table 2
2. Sea water temperature
Fill in the missing words.
The temperature of sea water from the equator to the poles drops from 27 to -1.7°C.
The temperature of sea water during immersion drops to +2°C.
When the salinity of sea water is 35%, the freezing point of sea water is -1.9°C.
Table 3
Table 4
The diagram (Fig. 1) shows the currents of surface waters of one of the regions of the World Ocean. Based on the outlines of large islands, determine the area of \u200b\u200bthe ocean, sign the names of currents and islands. On the map of the hemispheres of the atlas, check the correctness of the task.
Based on the satellite image (textbook, p. 157, fig. 95), determine the main direction of movement sea waters in the southeastern part of the Baltic Sea.
Direction northeast.
4. Ebb and flow
5. Ocean description example
Based on the text of the textbook (pp. 157 - 158), draw up a plan for describing the Arctic Ocean. Using your plan, describe another ocean (of your choice).
1) Area and volume in the World Ocean.
2) The location of the ocean relative to the continents.
3) The connection of the ocean with other oceans.
4) The number of islands in the ocean.
The Atlantic Ocean is the second largest ocean on Earth after the Pacific Ocean. It lies between Greenland and Iceland in the north, Europe and Africa in the west, and Antarctica in the south.
The area is 91.6 million km2, of which about 16% is in the seas, bays and straits. The area of coastal seas is not large and does not exceed 1% of the total area. The volume of water is 329.7 million km³, which is equal to 25% of the volume of the World Ocean. The average depth is 3736 m, the greatest is 8742 m (Puerto Rico Trench). The average annual salinity of the ocean waters is 35‰. The Atlantic Ocean is heavily indented coastline with a pronounced division into regional water areas: seas and bays.
Pathfinder School
The work plan is given in the textbook (p. 158 - 159).
Conclusion. The global ocean conveyor has a closed loop and consists of warm and cold branches.
3. Characteristics of the oceanic water 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, that is, common table salt NaCl, predominates. Significantly less sulfates, that is, salts of sulfuric acid, are found in sea water (10.8%). All other substances account for only 0.5% of the total salt composition of sea water.
After sodium salts, magnesium salts are in second place in sea water. This metal is used in the manufacture of light and strong alloys required in mechanical engineering, especially in aircraft construction. Each cubic meter of sea water contains 1.3 kilograms of magnesium. The technology of 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, dolomites.
It is worth noting that bromine, discovered in 1826 by the French chemist A. Balard, is not contained in any mineral. You can get bromine only from sea water, where it is contained in a relatively small amount - 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 production of bromine and 60% of magnesium. Sodium and chlorine are extracted from sea water in significant quantities. As for edible (table) salt, a person has long received it from sea water by evaporation. Marine salt mines still operate in tropical countries, where salt is obtained directly from the shallow areas of the coast, fencing them off from the sea with dams. The technology here is not very sophisticated. The concentration of table salt in water is higher than the rest of the salts, and therefore, when evaporated, it is the first to precipitate. The crystals settled at the bottom are removed from the so-called mother liquor and washed with fresh water to remove the remains of magnesium salts, which give the salt a bitter taste.
A more advanced technology for extracting salt from sea water is used in numerous salt works in France and Spain, which supply large volumes of salt not only to the European market. For example, one of the new ways to produce salt is to install special seawater atomizers in the pools of salt works. Water turned into dust (suspension) has a huge evaporation area and from the smallest drops it evaporates instantly, and only salt falls on the ground.
The extraction of table salt from sea water 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 necessary for mankind 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 growing in the ocean.
Even gold is contained in ocean water, though in negligible amounts - 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 vaults of the Reichsbank with gold bars: the production costs would have exceeded the value of the 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 is already being mined from sea water on an industrial scale. Since 1986, the world's first plant for extracting uranium from sea water has been operating on the coast 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, more than 13 million tons of sea water must be filtered and subjected to ion treatment. But persistent in work, the Japanese cope with this work. Moreover, they are well aware of what atomic Energy. -)
An indicator of the amount of chemicals dissolved in water is a special characteristic called salinity. Salinity is the mass of all salts, expressed in grams, contained in 1 kg of sea water.. Salinity is measured in thousandths, 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 salinity slightly above average (34.87‰), while the waters of the Indian Ocean are slightly lower (34.58‰). This is where the freshening effect of the 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 salty in the open ocean are the waters of the polar regions of both hemispheres. This is due to the melting of continental ice, especially in the Southern Hemisphere, and large volumes of river runoff in the Northern Hemisphere.
Salinity increases towards the tropics. The highest concentration of salts is observed not at the equator, but in the latitude bands 3°-20° south and north of the equator. These bands are sometimes called salinity belts.
The fact that the surface water salinity is relatively low in the equatorial zone is explained by the fact that the equator is a zone of heavy tropical rains that desalinate the water. Often, around the equator, dense clouds cover the ocean from direct sunlight, which reduces the evaporation of water at such moments.
In marginal and especially inland seas, the 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 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 in any noticeable way.
The Baltic Sea, which extends far into the land, communicates with the ocean through several small and narrow straits, is located in the temperate climate zone and receives water from many major rivers and small rivers. Therefore, the Baltic is one of the most desalinated basins of the oceans. 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 due to 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 salty waters (above 36 ‰) are traced, which are formed due to the transfer of more salty tropical waters from the western margins of the oceans by deep countercurrents.
Salinity changes sharply only to depths of about 1500 m. Below this horizon, almost no fluctuations in salinity are observed. At great depths of different oceans, salinity indicators converge. Seasonal changes in salinity on the surface of the open ocean are insignificant, no more than 1 ‰.
An anomaly of salinity is considered by experts 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, one 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 by determining them, it is possible to measure the salinity of 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 - bottles, which provide sampling from different depths or from different layers of water. This process requires a lot of attention and care from hydrologists.
So, the main processes that affect 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 affected by the proximity of melting glaciers and the volume of fresh water brought by rivers.
In general, the percentage ratio of various salts in sea water in all areas of the ocean almost always remains the same. However, in some places, the chemical composition of sea water is significantly influenced by marine organisms. They use for their nutrition and development many substances dissolved in the sea, although in varying quantities. Some substances, such as phosphates and nitrogenous compounds, are consumed especially in large quantities. In areas where there are many marine organisms, the content of these substances in the water is somewhat reduced. The smallest organisms that make up plankton have a noticeable effect on the chemical processes occurring in sea water. They drift on 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 oceans. Current monitoring map(increase) .
What is the total salt content in the oceans? Now it is not difficult to answer this question. If we proceed from the fact that the total amount of water in the oceans is 1370 million cubic kilometers, and the average concentration of salts in sea water is 35‰, that is, 35 g per 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 as an 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 sea water. In this respect, the ocean, without exaggeration, can be considered inexhaustible.
Now it is necessary to answer an equally important question: why is there so much salt in the ocean?
For many years science has been dominated by the hypothesis that salt was brought into the sea by rivers. 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 37,000 years for the complete renewal of water in the World Ocean - approximately in such a time it is possible to fill the ocean with river runoff. And if we accept that in the geological history of the Earth there were at least one hundred thousand such periods, and the salt content in river water, on average, is about 1 gram per liter, then it turns out that for the entire geological history of the Earth, about 1 was carried into the ocean by rivers. 4*10 20 tons of salt. And according to the calculation of scientists, which we have just given, 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 of sea salt. If sodium and magnesium compounds with chlorine absolutely predominate in sea water (89% of the dry residue after evaporation of water and only 0.3% is calcium carbonate), then in river water calcium carbonate occupies the first place - over 60% of the dry residue, and sodium chlorides and magnesium together - only 5.2 percent.
Scientists have one assumption left: the ocean became salty in the process of its birth. The most ancient animals could not exist in slightly saline, and even more so in freshwater pools. This means that the composition of sea water has not changed since its inception. But what happened to the carbonates that came to the ocean along with river runoff over hundreds of millions of years? 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, brought by rivers into the ocean, are immediately removed from the solution by those marine plants and animals that need these minerals for their skeletons, shells and shells. As these living organisms die off, the calcium carbonate (CaCO 3 ) contained in them and silicon salts are deposited on the seabed in the form of sediments of organic origin. So living organisms throughout the entire time of 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 such as deuterium, uranium and even gold. But we did not mention the main and main mineral that is in the oceans - plain water. H 2 O. Without this “mineral”, there would be nothing on Earth at all: neither oceans, nor seas, nor us. We have already had the opportunity to talk about the basic physical properties of water. Therefore, here we restrict ourselves to only a few remarks.
Throughout the 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 mysteries of water, for example, such remain: 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 the window panes on frosty days? Instead of amorphous snow and ice, we see ice crystals lined up in such an amazing way that they look like leaves and branches of some fabulous trees.
Or here's another. Two gaseous substances - oxygen and hydrogen, combined together, turned into a liquid. Many other substances, including solids, when combined with hydrogen, become, like hydrogen, gaseous, 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. It is said that it dissolves, albeit to a vanishingly small extent, even the glass of the glass into which we have 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 unique solution in terms of the variety of components, which eventually turned out to be a favorable environment for the emergence and maintenance of organic life.
In the first chapter of this story of ours, we have already noted what is almost universally recognized. 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 the actual data of 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 terms of the composition of salts dissolved in them is 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 molluscs to mammals.
It turned out that not only blood, but the entire internal environment of our body shows traces that have been preserved from the long stay of our distant ancestors in sea water.
At present, world science has no doubts about the oceanic origin of life on Earth.
© Vladimir Kalanov,
"Knowledge is power"
Seventy percent of the surface of our planet is covered with water - most of it is 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 so good?" 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 salinity is not the same in different parts of the hydrosphere. Several factors influence its change:
- ice formation;
- evaporation;
- precipitation;
- currents;
- river flow;
- melting ice.
While the water from the surface of the ocean evaporates, the salt does not erode and remains. Her concentration is increasing. The freezing process has a similar effect. Glaciers contain the largest supply of fresh water on the planet. The salinity of the oceans during their formation increases.
The opposite effect is characterized by the melting of glaciers, in which the salt content decreases. Salt also comes from rivers flowing into the ocean and 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, the concentration of salt in the oceans is always greater than in the seas, and location does not have any effect on this. This fact is not explained.
Salinity is due to the presence of magnesium and sodium. One of the options for explaining the different concentrations is the presence of certain land areas enriched in deposits of such components. However, such an explanation is not very plausible, if we take into account the sea currents. Thanks to them, over time, the salt level should stabilize throughout the volume.
World Ocean
The salinity of the ocean depends on the geographical latitude, the proximity of rivers, climatic features objects etc. Its average value according to the measurement is 35 ppm.
Near the Antarctic and the Arctic in cold areas, the concentration is less, 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.
In the Atlantic and Pacific oceans, the concentration of salt is approximately the same, 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 the presence of salt in the ocean. Scientists believe that the reason is the ability of water masses to destroy the rock, leaching easily soluble elements from it. This process is ongoing. Salt saturates the seas and gives a bitter taste.
However, there are diametrically opposed opinions on this issue:
Volcanic activity decreased over time, and the atmosphere cleared of vapor. 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.
) or PSU units (Practical Salinity Units) of the practical salinity scale (Practical Salinity Scale).
| Element | Content, mg/l |
|---|---|
| Chlorine | 19 500 |
| Sodium | 10 833 |
| Magnesium | 1 311 |
| Sulfur | 910 |
| Calcium | 412 |
| Potassium | 390 |
| Bromine | 65 |
| Carbon | 20 |
| Strontium | 13 |
| Bor | 4,5 |
| Fluorine | 1,0 |
| Silicon | 0,5 |
| Rubidium | 0,2 |
| Nitrogen | 0,1 |
Salinity in ppm 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, organic matter is burned.
In 1978, the practical salinity scale (Practical Salinity Scale 1978, PSS-78) was introduced and approved by all international oceanographic organizations, in which salinity measurement is based on electrical conductivity (conductometry), and not on water evaporation. In the 1970s, oceanographic CTD probes became widely used in marine research, and since then, water salinity has been measured mainly by electrical methods. To verify the operation of electrical conductivity cells that are immersed in water, laboratory salt meters are used. In turn, standard sea water is used to check salt meters. Standard sea water recommended international organization IAPSO for calibration of salt meters, produced in the UK by Ocean Scientific International Limited (OSIL) from natural sea water. If all measurement standards are followed, salinity measurement accuracy up to 0.001 PSU can be achieved.
The PSS-78 gives numerical results that are close to measurements of mass fractions, and differences are noticeable either when measurements with an accuracy better than 0.01 PSU are needed, or when the salt composition does not correspond to the standard composition of ocean water.
- Atlantic Ocean - 35.4 ‰ The highest salinity of surface waters in the open ocean is observed in the subtropical zone (up to 37.25 ‰), and the maximum is in the Mediterranean Sea: 39 ‰. In the equatorial zone, where the maximum amount of precipitation is noted, salinity decreases to 34 ‰. A sharp desalination of water occurs in the estuarine areas (for example, at the mouth of La Plata - 18-19 ‰).
- Indian Ocean - 34.8 ‰. The maximum salinity of surface waters is observed in the Persian Gulf and the Red Sea, where it reaches 40-41 ‰. High salinity (more than 36 ‰) is also observed in the southern tropical zone, especially in the eastern regions, and in the northern hemisphere also in the Arabian Sea. In the neighboring Bay of Bengal, due to the desalination effect of the Ganges runoff from the Brahmaputra and the Irrawaddy, the salinity is reduced to 30-34 ‰. The seasonal difference in salinity is significant only in the Antarctic and equatorial zones. In winter, desalinated waters from the northeastern part of the ocean are carried by the monsoon current, forming a tongue of low salinity along 5°N. sh. In summer, this language disappears.
- Pacific Ocean - 34.5 ‰. Tropical zones have the maximum salinity (up to a maximum of 35.5-35.6 ‰), where intensive evaporation is combined with a relatively small amount of precipitation. To the east, under the influence of cold currents, salinity decreases. A large amount of precipitation also lowers salinity, especially at the equator and in the western circulation zones of temperate and subpolar latitudes.
- Northern Arctic ocean - 32 ‰. There are several layers of water masses in the Arctic Ocean. The surface layer has low temperature(below 0 °C) and low salinity. The latter is explained by the freshening effect of river runoff, melt water and very weak evaporation. Below, a subsurface layer stands out, colder (up to −1.8 °C) and more salty (up to 34.3 ‰), formed by mixing surface waters with the underlying intermediate water layer. The intermediate water layer is Atlantic water coming from the Greenland Sea with a positive temperature and high salinity (more than 37 ‰), spreading to a depth of 750-800 m. Deeper lies the deep water layer, which also forms in the Greenland Sea in winter, slowly creeping in a single stream from the strait between Greenland and Svalbard. The temperature of deep waters is about -0.9 ° C, salinity is close to 35 ‰. .
The salinity of ocean waters varies depending on the geographical latitude, from the open part of the ocean to the coast. In the surface waters of the oceans, it is lowered in the equatorial region, in polar latitudes.
| Name | Salinity, ‰ |
|---|---|
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 the 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 the inland seas, located in tropical latitudes, where there is little precipitation, few rivers, and high evaporation, are more saline than oceanic waters. These are the Mediterranean, Red and Persian Gulf seas. The Mediterranean Sea, characterized by a negative freshwater 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 about. Sicily it is 37-38%o, in the eastern part of the sea 39%0 and more.[ ...]
The salinity of the surface waters of the seas often differs significantly from the salinity of oceanic waters (sometimes it exceeds it, sometimes it turns out to be less). These differences are determined by the conditions of water exchange between the seas and the ocean, the influence of climate and land water runoff. The salinity of the surface waters of the seas, the water exchange of which occurs more or less freely, is close to oceanic. With difficult water exchange, the differences can be significant.[ ...]
The salinity of the Ocean is not a constant value. It depends on the climate (the ratio of precipitation and evaporation from the surface of the Ocean), the formation or melting of ice, sea currents, near the continents, on the influx of fresh river waters. In the open Ocean, salinity ranges from 32-38%; in the outskirts and mediterranean seas its fluctuations are much greater. 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 solutes is maintained in various parts Ocean, on its surface and in deep layers. Based on 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: salty waters of the World Ocean and inland seas; fresh waters of the land, concentrated in mountain ice, rivers, lakes, swamps. Consider environmental characteristics aquatic environment.[ ...]
The ocean belongs to the group of saline waters, while sea waters are sometimes brines (for example, the Red Sea) or semi-solid (for example, the Sea of \u200b\u200bAzov), that is, they have a sharply different concentration, less or more than the average, little changing 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 Mozhayskoye 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 the 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% falls on lakes and rivers. The most important and used for a variety of needs, river waters account for only 0.0002% of the total water reserves [Lvovich, 1974].[ ...]
In the Pacific Ocean, to the north of the subpolar front, the 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 the oceans averages 35%.[ ...]
The world ocean is heterogeneous both in salinity and in temperature. It is possible to distinguish isometric regions, layers and the thinnest layers in it. The highest water temperature in the ocean (404°C) was recorded at a hot spring 480 km off 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 found 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 the weather and climatic conditions, in the surrounding areas.[ ...]
The area of salt waters (seas, oceans) is just over 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, The groundwater. Thus, we can only use about 2.5 million km3 of water. But part of this water is polluted and unfit for consumption.[ ...]
The average salinity of the waters on the surface of various oceans is not the same: the Atlantic 35.4% o, the Pacific 34.9 ° / oo, the Indian 34.8% o. 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 water bodies on land and the glaciers of Antarctica, Greenland, polar archipelagos and mountain peaks. The oceans are divided into four main parts - Pacific, Atlantic, Indian, Arctic oceans. The waters of the World Ocean, going 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 differ little from the World Ocean. In the seas, the salinity of water can be higher than oceanic (35%), as, for example, in the Red Sea, up to 40%, or lower, as in the Baltic Sea, from 3 to 20%.[ ...]
Usually in water there are various impurities of organic and inorganic origin. Distinguish between salt and fresh water. The main mass of water on our planet is salt water, which forms 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 look very distinct in the fields of temperature and salinity, while in the density field they are almost not expressed. Abrupt changes properties at the fronts turn out to be significant due to the fact that they affect the dynamics. A review of satellite observations over temperature fronts is made in . The main climatic frontal zones (where fronts are most often recorded) in the northern part of the 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 the Ekman convergence in the surface layer. Examples of such fronts are subtropical fronts, which are observed at latitudes from 30 ° N. sh. up to 40°S sh. Their changes associated with fluctuations in the Ekman divergence were studied in . The second type of fronts is formed at the boundary of water masses (see). Such a front separates, for example, the waters of the subarctic and subtropical gyres. In the northern part of the Pacific Ocean (Fig. 13.11), this front is located at a latitude of 42 ° N. sh. It was formed at the meeting place of the cold, equator-directed, Oyashio current with the warm current of the polar direction - Kuroshio. On the surface, this front is well expressed in the sections of temperature and salinity, but in the density field it is hardly noticeable.[ ...]
In the World Ocean, physical, chemical, biological and other processes continuously occur that change the salinity, i.e., reduce or increase the concentration of the solution. However, regardless of the absolute concentration of the solution, the quantitative ratios between the main ions remain constant. Therefore, it is sufficient to know the concentration of one of the components in order to determine the rest. To determine salinity, the sum of ions Cl + Br + I, called chlorine content, is used, the concentration of which in sea water is the highest.[ ...]
The bulk of the water is concentrated in the oceans. Its average depth is more than 4000 m, it covers an area equal to 361 million km2 (71% of the surface the globe), and has a high salinity (3.5%). Continental water bodies 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 supply 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 marine. It is significantly less salty and contains three times more carbonates than the water of the oceans. By modern concepts the salinity of the water of the seas and oceans is "primary", not changing during geological periods.[ ...]
Processes that change oceanological characteristics are continuously taking place in the World Ocean. As a result of uneven changes in these characteristics, their horizontal and vertical gradients arise, simultaneously with which processes are developed aimed at equalizing the properties of water masses and destroying the 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 values. The gradient of each of these values 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 waters tend to rise, and heavy ones tend 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, while in the underlying layer it increases. In the water layer located above the shock layer, the processes of water mixing occur most intensively; this layer is called the active layer. Below the water jump layer, they become stable, since here the temperature decreases with depth, and salinity and density increase.[ ...]
Salinity fluctuations 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 fresh water inflow is more intense in spring, as well as in polar regions due to the processes of freezing and melting of ice.[ ...]
Fresh water reserves make up less than 2% of water resources. The average salinity of the waters of the World Ocean is 3.5 g / l (in the oceans 48-1015 tons of 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 only from the coast of the Arctic and Greenland. The annual river runoff is estimated at 41,000 km'. In Europe and Asia, where 70% of the population lives, only 39% of the world's river water reserves are concentrated. The world's most abundant lake Baikal (23 thousand km3) contains 20% of the world's surface fresh water reserves. Russia has the world's largest underground water storage - 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 said to be homogeneous. If the vertical density distribution depends only on pressure, then one speaks 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 the oceans averages 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, 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, with a salt concentration of up to 25 g / kg - brackish, and at a higher concentration - salty. In the ocean, the concentration of salts is about 35 g / kg, in fresh lakes, rivers 5-1000 mg / kg. Sea water is a multicomponent system that includes 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 one can speak of 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 content of chlorine, all carbonic salts are converted into 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 thousandths - 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 are the subject of classical oceanography; the second term is heterogeneities related to the phenomenon of fine thermohaline structure; the third term is microturbulence according to Reynolds; tr - values of spatial and temporal scales delimiting the structural elements of water masses, due to the thin layered structure and turbulence. As a rule, the irregularity of vertical salinity profiles is greater than the irregularity of temperature distributions. Sea water has another interesting property. If the rates of molecular diffusion of heat and moisture in the atmosphere 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 that determine the formation of a fine thermohaline structure of sea waters.[ ...]
Since information about the fields of temperature and salinity makes it possible to calculate currents only with respect to some 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 transfers and compare them with calculations using the Sverdrup ratio. 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 currents at a depth of 1500 m. If we assume that the last currents are relatively weak, then Fig. 12.7.6 can be viewed as a picture of near-surface geostrophic currents. It shows many conspicuous coincidences with Fig. 12.7, a, which indicates that the effect of wind largely explains the pattern of surface circulation. On the other hand, significant differences, which 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 sinking of the waters in the Greenland Sea carries large masses of surface water there from the North Atlantic, 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 stratification of water masses is associated mainly with the processes of vertical exchange, and at depth the heterogeneity of oceanological characteristics is associated with the general circulation of the 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 intrusion, of water masses carried from outside by currents. An example is the presence of warm Atlantic waters in the entire central part of the Arctic Ocean, which can be traced at depths from 150–250 to 800–900 m. contacts arise? vertical gradients of oceanographic characteristics. The transition layer, in which the gradients of temperature, salinity, density and other properties are large, is called the jump layer. These layers may be temporary, seasonal, or permanent in the active layer and on its boundary with deep waters. Deep-water observations in various regions of the World Ocean (Fig. 14) show that in open regions, 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 almost does not change. 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 poisonous plums, then since ancient times the waters are divided into salty and fresh. Salt waters, compared to fresh waters, contain increased concentration salts, especially sodium salts. They are not suitable for drinking and industrial use, but are excellent for swimming and water transport. The salt composition of saline waters in different water bodies varies quite a lot: for example, in the shallow Gulf of Finland, the waters are less saline than in the Black Sea, and in the oceans, the salinity is much higher. I want to remind you that salt water is not necessarily sea water. There are known basins with exceptionally salty waters that have no connection 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 swim in the ocean for a long time without damage and without loss of seed germination. Since ancient times, accidentally falling into the Atlantic Ocean, the fruits of lagenaria, picked up by ocean currents, sailed from the coast of West Africa to Brazil or through Pacific Ocean came 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 oceans and seas. Since salinity is the most conservative, established property of the waters of the World Ocean, we can also talk about the balance of salts. The incoming part of the salt balance is made up of the inflow of salts: a) with continental runoff, b) with atmospheric precipitation, c) from the Earth's cedar in the form of mantle degassing products, d) during the dissolution of rocks at the bottom of the oceans and seas.[ ...]
Hydrosphere - 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 salt 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 removal of salts by rivers into the ocean would double the concentration of salts every 80 million years, if not for the 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 decomposition processes organic matter sewage in the seas and oceans flow much more slowly compared to freshwater basins. This is due to the fact that the concentration of salts in salt water is greater than in fresh water and therefore the osmotic pressure with which the microbial cell absorbs the nutrients necessary for its life decreases (Gaultier, 1954). Accordingly, the decrease in the value of BODz in sea water in the process of its self-purification occurs much more slowly than in fresh water.[ ...]
Moderate and tropical belts the land masses, with their humid climate and developed biostrome, continue on the ocean as belts of 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.[ ...]
A small amount of work, of course, could not contain the huge information that is associated with the problem of water desalination. But we have tried to show that the idea of obtaining fresh water from the colossal salt 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 on the sun-scorched, waterless land thanks to the found ways to desalinate sea water 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 entry of more saline waters into the Atlantic Ocean could lead in three decades to such a decrease in salinity in it that it would entail a complete change in the circulation of ocean waters, the result of which could eventually be the cessation of warm waters Gulf Stream to the Arctic and cooling there with simultaneous warming in continental Europe. At one time, this forecast caused a negative reaction from another well-known oceanologist G. Stommel, who pointed out that on the basis of M. Ewing's assumptions, reverse processes could be predicted with the same 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 water mass exchange.[ ...]
Various water masses are separated by frontal zones or frontal surfaces, in which the gradients of water mass characteristics become sharper. Quasi-stationary climatic frontal zones are the natural boundaries of the main water masses in the ocean. Five types of fronts are distinguished in the open ocean: equatorial, subequatorial, tropical, subpolar, and polar. The frontal zones are distinguished by the high dynamism of the processes occurring in them. In the coastal zone, in the estuarine zone, fronts are formed that separate the shelf or runoff waters from the waters of the deep part. The formation of one or another type of front 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. flow of fresh river water over saline and dense sea water. In the case of the inflow of Baltic waters into the lagoon, an intrusion front of heavy sea waters into the lighter waters of the lagoon is formed. When a wedge of saline sea waters propagates along a deep sea channel, a typical estuarine front is observed. A typical change in temperature, salinity and density at the front crossing is shown in fig. 6.5.[...]
This type of renewable energy resources is perhaps the most exotic, and the youngest in development time: the first technical ideas date back only to the 70s. 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. This, as already noted, consumes about 54% of the total balance of energy coming from the Sun. 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 magnitude of the change in the 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, in the mouths of rivers 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 H2O 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.[ ...]
At present, work on the organization of irrigated agriculture for growing perennial grasses 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 intake is carried out from artificial reservoirs in which spring snow water accumulates. 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 blooming water, 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 G. of the Earth is shown in Table. 16. G. is 94% represented by the 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 section of Quaternary deposits corresponds to interglacial periods of high sea level, when the limitation of water exchange with the ocean was minimal. Coccolithophorites can withstand harsher conditions, but during the maximum of the last glaciation, salinity was so high that even the most tolerant forms eventually disappeared.
