hydrosphere (water shell of the Earth), which occupies the vast majority of it (more than $90\%$) and is a collection of water bodies (oceans, seas, bays, straits, etc.) washing land areas (continents, peninsulas, islands, etc.) .d.).
The area of the World Ocean is about $70\%$ of the planet Earth, which exceeds the area of the entire land by more than $2$ times.
The World Ocean, as the main part of the hydrosphere, is a special component - the oceanosphere, which is the object of study of the science of oceanology. Thanks to this scientific discipline, the component, as well as the physicochemical composition of the oceans are now known. Let us consider in more detail the component composition of the World Ocean.
The World Ocean can be componentally divided into its main components, independent large parts that communicate with each other - the oceans. In Russia, on the basis of the established classification, four separate oceans were distinguished from the composition of the World Ocean: the Pacific, Atlantic, Indian and Arctic. In some foreign countries, in addition to these four oceans, there is also a fifth one - the South (or the South Arctic), which combines the waters of the southern parts of the Pacific, Atlantic and Indian oceans surrounding Antarctica. However, due to the uncertainty of the boundaries, this ocean is not distinguished in the Russian classification of oceans.
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Seas
In turn, the component composition of the oceans includes seas, bays, straits.
Definition 2
Sea- this is a part of the ocean, limited by the shores of the continents, islands and bottom elevations and differing from neighboring objects in physico-chemical, environmental and other conditions, as well as characteristic hydrological features.
According to morphological and hydrological features, the seas are divided into marginal, mediterranean and interisland.
The marginal seas are located on the underwater margins of the continents, the shelf zone, in transition zones and are separated from the ocean by islands, archipelagos, peninsulas or underwater rapids.
The seas that are confined to continental shallows are shallow. For example, the Yellow Sea has a maximum depth of $106$ meters, and those seas that are located in the so-called transitional zones are characterized by depths of up to $4,000$ meters - the Sea of Okhotsk, the Bering Sea, and so on.
The water of the marginal seas practically does not differ in physical and chemical composition from the open waters of the oceans, because these seas have an extensive connection front with the oceans.
Definition 3
mediterranean called seas that cut deep into the land and are connected to the waters of the oceans by one or more small straits. This feature of the Mediterranean seas explains the difficulty of their water exchange with the waters of the oceans, which forms a special hydrological regime of these seas. The Mediterranean seas include the Mediterranean, Black, Azov, Red and other seas. The Mediterranean seas, in turn, are divided into intercontinental and intracontinental.
Interisland seas are separated from the oceans by islands or archipelagos, consisting of rings of individual islands or island arcs. Such seas include the Philippine Sea, the Fiji Sea, the Banda Sea, and others. The Sargasso Sea also belongs to the inter-island seas, which does not have definitely established and pronounced boundaries, but has a pronounced and specific hydrological regime and special types of marine flora and fauna.
Gulfs and straits
Definition 4
gulf- this is a part of the ocean or sea, protruding into the land, but not separated from it by an underwater threshold.
Depending on the nature of origin, hydrogeological features, forms of the coastline, shape, as well as confinement to a particular region or country, the bays are divided into: fjords, bays, lagoons, estuaries, bays, estuaries, harbors and others. The Gulf of Guinea, washing the coast of the countries of Central and West Africa, is recognized as the largest in area.
In turn, the oceans, seas and bays are interconnected by relatively narrow parts of the ocean or sea, which separate the continents or islands - straits. The straits have their own special hydrological regime, a special system of currents. The Drake Passage, which separates South America and Antarctica, is considered the widest and deepest strait. Its average width is 986 kilometers and a depth of more than 3,000 meters.
Physical and chemical composition of the waters of the World Ocean
Sea water is a highly dilute solution of mineral salts, various gases and organic matter, containing in its composition suspensions of both organic and inorganic origin.
A series of physicochemical, ecological and biological processes constantly occur in sea water, which directly affect the change in the overall composition of the solution concentration. The composition and concentration of mineral and organic substances in ocean water are actively affected by the inflows of fresh water flowing into the oceans, the evaporation of water from the surface of the ocean, precipitation on the surface of the World Ocean, and the processes of formation and melting of ice.
Remark 1
Some processes, such as the activity of marine organisms, the formation and decay of bottom sediments, are aimed at changing the content and concentration of solids in water and, as a result, at changing the ratio between them. The respiration of living organisms, the process of photosynthesis and the activity of bacteria affect the change in the concentration of dissolved gases in water. Despite this, all these processes do not violate the concentration of the salt composition of water in relation to the main elements included in the solution.
Salts and other mineral and organic substances dissolved in water are predominantly in the form of ions. The composition of salts is diverse, almost all chemical elements are found in ocean water, but the main mass is made up of the following ions:
- $Na^+$
- $SO_4$
- $Mg_2^+$
- $Ca_2^+$
- $HCO_3,\CO$
- $H2_BO_3$
The highest concentrations in sea waters contain chlorine - $1.9\%$, sodium - $1.06\%$, magnesium - $0.13\%$, sulfur - $0.088\%$, calcium - $0.040\%$, potassium - $0.038\%$, bromine $0.0065\%$, carbon $0.003\%$. The content of other elements is insignificant and amounts to about $0.05\%.$
The total mass of matter dissolved in the World Ocean is more than $50,000$ tons.
Precious metals were found in the waters and at the bottom of the World Ocean, but their concentration is insignificant and, accordingly, their extraction is unprofitable. Ocean water in its chemical composition is strikingly different from the composition of land waters.
The salt concentration and salt composition in different parts of the World Ocean is not uniform, however, the greatest differences in salinity are observed in the surface layers of the ocean, which is explained by exposure to various external factors.
The main factor that makes adjustments to the concentration of salts in the waters of the World Ocean is atmospheric precipitation and evaporation from the water surface. The lowest salinity values on the surface of the World Ocean are observed at high latitudes, since these regions have an excess of precipitation over evaporation, significant river runoff and melting of floating ice. As you approach the tropical zone, salinity increases. In the equatorial latitudes, the amount of precipitation increases, and the salinity here again decreases. The vertical distribution of salinity is different in different latitudinal zones, but deeper than $1500$ meters, salinity remains almost constant and does not depend on latitude.
Remark 2
Also, in addition to salinity, one of the main physical properties of sea water is its transparency. The transparency of water is understood as the depth at which the white disc of Secchi with a diameter of $30$ centimeters ceases to be visible to the naked eye. The transparency of water depends, as a rule, on the content of suspended particles of various origins in the water.
The color or color of water also largely depends on the concentration of suspended particles, dissolved gases, and other impurities in the water. The color can vary from blue, turquoise and blue hues in clear tropical waters to blue-green and greenish and yellowish hues in coastal waters.
Water is the most abundant substance on earth. The water shell of the Earth developed along with the lithosphere, atmosphere and wildlife. Almost all processes on our planet proceed with the participation of water. The hydrosphere consists of the oceans, land waters and groundwater. The bulk of the water is concentrated in the oceans.
The World Ocean is the blue mirror of our planet, the cradle of life on Earth. It contains not only the past, but also the future of our planet. To understand the great role of the ocean, it is necessary to know the features of its nature: the properties of water masses, to understand the role of currents, the significance of the interaction of the ocean with the atmosphere and land. You will learn about all this by studying this topic.
§ 9. Waters of the oceans
- What is called the hydrosphere? World Ocean?
- What do you already know about the nature of the ocean?
- Make a characterization of the map of the oceans (see the plan in the appendix).
The role of the ocean in the life of the Earth. The ocean occupies almost 3/4 of the surface of our planet (Fig. 22). Water is one of the most amazing substances on Earth, a precious liquid, a gift of nature to our planet. In such quantities as on Earth, it is not found anywhere in the solar system.
Rice. 22. The area of land and ocean: a) in general on Earth; b) in the Northern Hemisphere; c) in the southern hemisphere
The ocean... It is hard to imagine how great its importance in the life of the Earth. Clouds in the sky, rain and snow, rivers and lakes, springs - all these are particles of the ocean that have only temporarily left it.
The ocean determines many features of the nature of the Earth: it gives the atmosphere the accumulated heat, nourishes it with moisture, part of which is transferred to the land. It has a great influence on the climate, soil, flora and fauna of the land. Its role in human economic activity is great. The ocean is a healer, giving medicines and taking millions of vacationers to its shores. He is a source of seafood, many minerals, energy; he is the "kitchen of the weather", and the most spacious road in the world connecting the continents. Thanks to the work of bacteria, the ocean has the ability (up to a certain limit) to cleanse itself, and therefore many of the waste generated on Earth is destroyed in it.
The history of mankind is inextricably linked with the study and development of the ocean. Its knowledge began in ancient times. (When? By whom?) Especially a lot of new data has been obtained over the past decades with the help of the latest technology. Research carried out on scientific ships, collected by automatic oceanographic stations, as well as artificial Earth satellites, helped to detect eddies in the waters of the ocean, deep countercurrents, and prove the existence of life at great depths. The study of the structure of the ocean floor made it possible to create a theory of the movement of lithospheric plates.
Origin of the waters of the oceans. The ocean is the main custodian of water, the most common substance on Earth, which has long amazed researchers with its unusual properties. Only water under normal terrestrial conditions can be in three states. This property ensures the omnipresence of water. It permeates the entire geographic shell and performs a variety of work in it.
How did water appear on Earth? Finally, this “survey” has not yet been resolved by science. It is assumed that water either released immediately during the formation of the lithosphere from the upper mantle, or accumulated gradually. Water is still released from magma, falling on the surface of the planet during volcanic eruptions, during the formation of oceanic crust in the zones of stretching of lithospheric plates. This will continue for many millions of years. Part of the water comes to Earth from space.
properties of ocean waters. Their most characteristic properties - salinity and temperature - are already known to you. (Recall their key figures from Year 6.) Oceanic mode is a weak solution in which almost no chemicals are found. Gases, mineral and organic substances, formed as a result of vital activity of organisms, are dissolved in it.
The main changes in salinity are observed in the surface layer. The salinity of waters depends mainly on the ratio of atmospheric precipitation and evaporation, which varies depending on the geographical latitude. At the equator, the salinity is about 34%.., near the tropics - 36%, and in temperate and polar latitudes - about 33%. Salinity is less where the amount of precipitation exceeds evaporation, where there is a large influx of river waters, where ice melts.
You know that the waters of the ocean are heated, like the land, from the influx of solar heat on its surface. Occupying a large area, the ocean receives more heat than land. The temperature of surface waters varies and is distributed depending on the latitude (Fig. 23). In some areas of the ocean, this regularity is disturbed by ocean currents, and in coastal parts, by the runoff of warmer waters from the continents. The temperature of the ocean water also changes with depth. At first, its decrease is very significant, and then it slows down. At depths of more than 3-4 thousand meters, the temperature usually ranges from +2 to 0 °C.
Rice. 23. The average annual water temperature on the surface of the oceans. Compare water temperatures at the same latitudes. Explain the result
Ice in the ocean. The formation of ice depends on the temperature of ocean waters. You already know that sea water freezes at -2°C. As salt water cools, the density of salt water increases, its upper layer becomes heavier and sinks down, and warmer layers of water rise to the surface. This mixing of the water prevents the formation of ice. Ice forms only in arctic and subarctic latitudes, where winters are long and very cold. Some shallow seas located in the temperate zone also freeze. Distinguish between annual and multi-year ice. Ocean ice can be immobile if it is connected to the land, or floating, i.e. drifting. In the ocean, there are ices that have broken off from the glaciers of the land and descended into the ocean - icebergs (Fig. 24).
Rice. 24. Melting icebergs in the ocean
The ice cover of the ocean has a huge impact on the climate of the Earth, on life in it. Ice reflects the sun's rays, cools the air, and contributes to the formation of fogs. They impede navigation and marine fisheries.
water masses. Water is the main component of the nature of the ocean. Large volumes of water that form in certain parts of the ocean and differ from each other in temperature, salinity, density, transparency, the amount of oxygen, the presence of certain living organisms, are called water masses. These properties are preserved throughout the space occupied by one or another water mass.
In the ocean, surface, intermediate, deep, and bottom water masses are distinguished. In surface fashionable masses up to a depth of 200 m, equatorial masses are distinguished. tropical, temperate and polar water masses. They are formed as a result of the uneven supply of solar heat at different latitudes and the influence of the atmosphere. In the same latitudes, the properties of surface water masses may differ, therefore, coastal and intra-oceanic masses are also distinguished.
Water masses actively interact with the atmosphere: they give it heat and moisture, absorb carbon dioxide from it, and release oxygen. When mixed, they change their properties.
- What determines the salinity of ocean waters?
- What are the differences in ocean water temperature?
- Where does ice form in the ocean? How do they affect the nature of the Earth and human economic activity?
- What is a water mass? Name the main types of water masses. What water masses are isolated in the surface layer of the ocean?
The only source of practical importance that controls the light and heat regime of water bodies is the sun.
If the sun's rays falling on the surface of the water are partly reflected, partly spent on the evaporation of water and illuminating the layer where they penetrate, and partly absorbed, then it is obvious that the heating of the surface layer of water occurs only due to the absorbed part of the solar energy.
It is no less obvious that the laws of heat distribution on the surface of the World Ocean are the same as the laws of heat distribution on the surface of continents. Particular differences are explained by the high heat capacity of water and the greater homogeneity of water compared to land.
In the northern hemisphere, the oceans are warmer than in the southern, because in the southern hemisphere there is less land, which strongly heats the atmosphere, and there is also wide access to the cold Antarctic region; in the northern hemisphere there is more land, and the polar seas are more or less isolated. The thermal equator of water is located in the northern hemisphere. Temperatures naturally decrease from the equator to the poles.
The average surface temperature of the entire World Ocean is 17°.4, i.e., 3° higher than the average air temperature on the globe. The high heat capacity of water and turbulent mixing explain the presence of large reserves of heat in the oceans. For fresh water, it is equal to I, for sea water (with a salinity of 35‰) it is slightly less, namely 0.932. On average annual output, the warmest ocean is the Pacific (19°.1), followed by the Indian (17°) and the Atlantic (16°.9).
Temperature fluctuations on the surface of the World Ocean are immeasurably smaller than air temperature fluctuations over the continents. The lowest reliable temperature observed on the surface of the ocean is -2°, the highest is +36°. Thus, the absolute amplitude is not more than 38°. As for the amplitudes of average temperatures, they are even narrower. The daily amplitudes do not go beyond 1°, and the annual amplitudes, which characterize the difference between the average temperatures of the coldest and warmest months, range from 1 to 15°. In the northern hemisphere for the sea, the warmest month is August, the coldest is February; vice versa in the southern hemisphere.
According to thermal conditions in the surface layers of the World Ocean, tropical waters, waters of the polar regions and waters of temperate regions are distinguished.
Tropical waters are located on both sides of the equator. Here in the upper layers the temperature never drops below 15-17°, and in large areas the water has a temperature of 20-25° and even 28°. Annual temperature fluctuations do not exceed 2° on average.
The waters of the polar regions (in the northern hemisphere they are called arctic, in the southern hemisphere antarctic) are distinguished by low temperatures, usually below 4-5 °. The annual amplitudes here are also small, as in the tropics - only 2-3°.
The waters of the temperate regions occupy an intermediate position - both territorially and in some of their features. Part of them, located in the northern hemisphere, was called the boreal region, in the southern - the notal region. In boreal waters, the annual amplitudes reach 10°, and in the notal region, they are half as much.
The transfer of heat from the surface and the depths of the ocean is practically carried out only by convection, i.e., by the vertical movement of water, which is caused by the fact that the upper layers turned out to be denser than the lower ones.
The vertical temperature distribution has its own characteristics for the polar regions and for the hot and temperate regions of the World Ocean. These features can be summarized in the form of a graph. The upper line represents the vertical temperature distribution at 3°S. sh. and 31°W d. in the Atlantic Ocean, i.e., serves as an example of a vertical distribution in tropical seas. What is striking is the slow drop in temperature in the very surface layer, the sharp drop in temperature from a depth of 50 m to a depth of 800 m, and then again a very slow drop from a depth of 800 m and below: the temperature here almost does not change, and, moreover, it is very low (less than 4 °C). ). This constancy of temperature at great depths is explained by the complete rest of the water.
The lower line represents the vertical temperature distribution at 84°N. sh. and 80 ° in. etc., i.e. serves as an example of a vertical distribution in the polar seas. It is characterized by the presence of a warm layer at a depth of 200 to 800 m, overlapped and underlain by cold water with negative temperatures. The warm layers found both in the Arctic and in the Antarctic were formed as a result of the sinking of waters brought to the polar countries by warm currents, because these waters, due to their higher salinity compared to the desalinated surface layers of the polar seas, turned out to be denser and, therefore, heavier than local polar waters.
In short, in temperate and tropical latitudes, there is a steady decrease in temperature with depth, only the rates of this decrease are different at different intervals: the smallest near the surface itself and deeper than 800-1000 m, the largest in the interval between these layers. For the polar seas, that is, for the Arctic Ocean and the southern polar space of the other three oceans, the pattern is different: the upper layer has low temperatures; with depth, these temperatures, rising, form a warm layer with positive temperatures, and under this layer, temperatures again decrease, with their transition to negative values.
This is the picture of vertical temperature changes in the oceans. As for individual seas, the vertical temperature distribution in them often deviates greatly from the patterns that we have just established for the World Ocean.
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The main mass of the Earth's water shell is formed by the salty waters of the World Ocean, covering 2/3 of the Earth's surface. Their volume is approximately 1379106 km3, while the volume of all land waters (including glaciers and groundwater to a depth of 5 km) is less than 90106 km3. Since oceanic waters make up about 93% of all waters in the biosphere, it can be assumed that their chemical composition determines the main features of the composition of the hydrosphere as a whole.
The modern chemical composition of the ocean is the result of its long-term change under the influence of the activities of living organisms. The formation of the primary ocean was due to the same processes of degassing of the planet's solid matter that led to the formation of the Earth's gaseous envelope. For this reason, the composition of the atmosphere and the hydrosphere is closely related, their evolution was also interconnected.
As noted earlier, water vapor and carbon dioxide dominated among the degassing products. From the moment the surface temperature of the planet dropped below 100 ° C, water vapor began to condense and form primary reservoirs. On the surface of the Earth, the process of the water cycle arose, which marked the beginning of the cyclic migration of chemical elements in the land-ocean-land system.
In accordance with the composition of the released gases, the first accumulations of water on the planet's surface were acidic, enriched mainly in HC1, as well as HF, H3BO3, and H2S. Ocean water has gone through many cycles. Acid rains vigorously destroyed aluminosilicates, extracting easily soluble cations from them - sodium, potassium, calcium, magnesium, which accumulated in the ocean. Cations gradually neutralized strong acids, and the waters of the ancient hydrosphere acquired a chlorine-calcium composition.
Among the various processes of transformation of degassable compounds, apparently, the activity of condensations of thermolithotrophic bacteria took place. The appearance of cyanobacteria that lived in water, protecting them from harmful ultraviolet radiation, marked the beginning of photosynthesis and biogeochemical oxygen production. The decrease in the partial pressure of CO2 due to photosynthesis contributed to the precipitation of large masses of carbonates Fe2+, then Mg2+ and Ca3+.
Free oxygen began to flow into the waters of the ancient ocean. Over a long period of time, reduced and underoxidized compounds of sulfur, ferrous iron and manganese were oxidized. The composition of oceanic water acquired a chloride-sulfate composition close to the modern one.
Chemical elements in the hydrosphere are in various forms. Among them, the most characteristic are simple and complex ions, as well as molecules that are in a state of highly dilute solutions. There are widespread ions that are sorption bound with particles of colloidal and subcolloidal sizes present in sea water in the form of a fine suspension. A special group is made up of elements of organic compounds.
The total amount of dissolved compounds in sea water (salinity) in the surface layers of the oceans and marginal seas ranges from 3.2 to 4%. In inland seas, salinity varies over a wider range. The average salinity of the World Ocean is assumed to be 35%.
Even in the middle of the XIX century. scientists have discovered a remarkable geochemical feature of ocean water: despite fluctuations in salinity, the ratio of the main ions remains constant. The salt composition of the ocean is a kind of geochemical constant.
As a result of the persistent work of scientists from many countries, extensive analytical material has been accumulated that characterizes the content in the water of the seas and oceans of not only the main, but also trace elements. The most substantiated data on the average values (clarks) of chemical elements in the water of the World Ocean are given in the reports of E.D. Goldberg (1963), A.P. Vinogradov (1967), B. Mason (1971), G. Horn (1972), A.P. Lisitsina (1983), K.N. Turekiana (1969). In table. 4.1 mainly uses the results of the last two authors.
As can be seen from the above data, the bulk of dissolved compounds are chlorides of common alkaline and alkaline earth elements, sulfates are less, and even less are hydrocarbonates. The concentration of trace elements, the unit of which is µg/l, is three mathematical orders of magnitude lower than in rocks. The range of clarks of scattered elements reaches 10 mathematical orders, i.e. approximately the same as in the earth's crust, but the ratios of the elements are completely different. Bromine, strontium, boron and fluorine clearly dominate, the concentration of which is above 1000 µg/l. Iodine and barium are present in significant amounts, their concentration exceeds 10 µg/l.
Table 4.1
The content of soluble forms of chemical elements in the oceans.| Chemical element or ion | Average concentration | The ratio of the concentration in the amount of salts to the clarke of the granite layer | Total weight, mln t | |
| in water, µg/l | in the amount of salts, 10 -4 % | |||
| C1 | 19 353 000,0 | 5529,0 | 3252,0 | 26513610000 |
| SO 4 2 — | 2 701 000,0 | 771,0 | - | 3700370000 |
| S | 890000,0 | 254,0 | 63,0 | 1216300000 |
| NSO 3 — | 143000,0 | 41,0 | - | 195910000 |
| Na | 10764000,0 | 3075,0 | 14,0 | 14746680000 |
| mg | 1297000,0 | 371,0 | 3,1 | 1776890000 |
| Sa | 408000,0 | 116,0 | 0,5 | 558960000 |
| To | 387000,0 | 111,0 | 0,4 | 530190000 |
| Vg | 67 300,0 | 1922,9 | 874,0 | 92 201 000 |
| Sr | 8100,0 | 231,4 | 1,0 | 1 1 097 000 |
| AT | 4450,0 | 127,1 | 13,0 | 6 096 500 |
| SiO2 | 6200,0 | 176,0 | - | 8494000 |
| Si | 3000,0 | 85,0 | 0,00028 | 4 1 10 000 |
| F | 1300,0 | 37,1 | 0,05 | 1 781 000 |
| N | 500,0 | 14,0 | 0,54 | 685 000 |
| R | 88,0 | 2,5 | 0,0031 | 120 560 |
| I | 64,0 | 1,8 | 3,6 | 87690 |
| Wa | 21,0 | 0,57 | 0,00084 | 28770 |
| Mo | 10,0 | 0,29 | 0,22 | 13700 |
| Zn | 5,0 | 0,14 | 0,0027 | 6850 |
| Fe | 3,4 | 0,097 | 0,0000027 | 4658 |
| U | 3,3 | 0,094 | 0,036 | 4521 |
| As | 2,6 | 0,074 | 0,039 | 3562 |
| Al | 1,0 | 0,029 | 0,00000036 | 1370 |
| Ti | 1,0 | 0,029 | 0,0000088 | 1370 |
| Cu | 0,90 | 0,025 | 0,001 1 | 1233 |
| Ni | 0,50 | 0,014 | 0,00054 | 685 |
| Mn | 0,40 | 0,011 | 0,000016 | 548 |
| Cr | 0,20 | 0,0057 | 0,00017 | 274 |
| hg | 0,15 | 0,0043 | 0,130 | 206 |
| CD | 0,11 | 0,0031 | 0,019 | 151 |
| Ag | 0,10 | 0,0029 | 0,065 | 137 |
| Se | 0,09 | 0,0026 | 0,019 | 123 |
| co | 0,03 | 0,00086 | 0,0012 | 41,1 |
| Ga | 0,03 | 0,00086 | 0,0012 | 41,1 |
| Pb | 0,03 | 0,00086 | 0,0012 | 41,1 |
| Zr | 0,026 | 0,00070 | 0,0000041 | 34,0 |
| sn | 0,020 | 0,00057 | 0,00021 | 27,4 |
| Au | 0,011 | 0,00031 | 0,26 | 15,1 |
Part of the metals in the water - molybdenum, zinc, uranium, titanium, copper - has a concentration of 1 to 10 µg/l. The concentration of nickel, manganese, cobalt, chromium, mercury, cadmium is much lower - hundredths and tenths of µg/l. At the same time, iron and aluminum, which play the role of the main elements in the earth's crust, have a lower concentration in the ocean than molybdenum and zinc. The least dissolved elements in the ocean are niobium, scandium, beryllium and thorium.
To determine some geochemical and biogeochemical indicators, it is necessary to know the concentration of elements not only in sea water, but also in the solid phase of soluble substances, i.e. in the amount of salts in sea water. The table shows the data, for the calculation of which the value of the average salinity is assumed to be 35 g/l.
As shown above, the leading factor in the evolution of the chemical composition of the ocean throughout geological history was the total biogeochemical activity of living organisms. Organisms play an equally important role in modern processes of differentiation of chemical elements in the ocean and the removal of their masses into sediment. According to the biofiltration hypothesis developed by A.P. Lisitsin, planktonic (mainly zooplankton) organisms daily filter through their bodies about 1.2107 km3 of water, or about 1% of the volume of the World Ocean. At the same time, thin mineral suspensions (particles with a size of 1 micron or less) bind into lumps (pellets). Pellets sizes from tens of micrometers to 1 - 4 mm. The binding of fine suspensions into lumps ensures a faster settling of the suspended material on the Bottom. At the same time, part of the chemical elements dissolved in water in the bodies of organisms passes into insoluble compounds. The most common examples of biogeochemical binding of dissolved elements into insoluble compounds are the formation of calcareous (calcite) and silicic (opal) skeletons of planktonic organisms, as well as the extraction of calcium carbonate by calcareous algae and corals.
Among pelagic silts (deep-sea sediments of the ocean), two groups can be distinguished. The former consist mainly of biogenic plankton formations, the latter are formed mainly by particles of non-biogenic origin. In the first group, calcareous (carbonate) silts are most common, in the second - clayey silts. Carbonate silts occupy about a third of the area of the bottom of the World Ocean, clayey - more than a quarter. In carbonate sediments, the concentration of not only calcium and magnesium, but also strontium and iodine increases. Silts, where clay components predominate, contain much more metals. Some elements are very weakly removed from solution into silts and gradually accumulate in sea water. They should be called talas-sophilic. Having calculated the ratio between the concentrations in the sum of soluble salts of sea water and silt, we will obtain the value of the thalassophylicity coefficient of CT, which shows how many times this element is more in the salt part of ocean water compared to sediment. Thalassophilic elements accumulating in the dissolved salt part of water have the following CT coefficients:
| Chemical element | Relative toto clay silts. | In relation to lime sludge |
| iodine | 180 0 | 36,0 |
| Bromine | 27 5 | 27 5 |
| Chromium | 27 0 | 27 0 |
| Sulfur | 19 5 | 19 5 |
| Sodium | . 7 7 | 15 4 |
| Magnesium | 1 8 | 0 9 |
| Strontium | 1 3 | 0 1 |
| Bor. | 06 | 2 3 |
| Potassium | 04 | 3 8 |
| Molybdenum | 0 01 | 10 0 |
| Lithium | 0.09 | 1.0 |
Knowing the mass of the element in the oceans and the value of its annual income, it is possible to determine the rate of its removal from the oceanic solution. For example, the amount of arsenic in the ocean is approximately 3.6109 t, with river runoff brought 74103 t/year. Consequently, for a period equal to 49 thousand years, there is a complete removal of the entire mass of arsenic from the oceans.
The assessment of the time spent by elements in a dissolved state in the ocean was undertaken by many authors: T.F. Bart (1961), E.D. Goldberg (1965), H.J. Bowen (1966), A.P. Vinogradov (1967) and others. The data of different authors have greater or lesser discrepancies. According to our calculations, the periods of complete removal of dissolved chemical elements from the World Ocean are characterized by the following time intervals (in years, in the sequence of increasing periods in each series):
- n*102: Th, Zr, Al, Y, Sc
- n*103: Pb, Sn, Mn, Fe, Co, Cu, Ni, Cr, Ti, Zn
- n*104: Ag, Cd, Si, Ba, As, Hg, N
- n*105: Mo, U, I
- n*106: Ca, F, Sr, B, K
- n*107: S, Na
- n*108: C1, Br
Despite the tentative nature of such calculations, the orders of magnitude obtained make it possible to distinguish groups of trace elements that differ in the duration of their stay in the oceanic solution. Elements that are most intensely concentrated in deep-sea silts have the shortest residence time in the ocean. These are thorium, zirconium, yttrium, scandium, aluminum. The periods of presence of lead, manganese, iron, and cobalt in the oceanic solution are close to them. Most of the metals are completely removed from the ocean over several thousand or tens of thousands of years. Thalassophilic elements have been in a dissolved state for hundreds of thousands of years or more.
Significant masses of dispersed elements in the ocean are bound by dispersed organic matter. Its main source is dying planktonic organisms. The process of destruction of their remains is most active up to a depth of 500-1000 m. Therefore, in the sediments of shelf and shallow continental seas, huge masses of dispersed organic matter of marine organisms accumulate, to which organic suspensions are added, taken out by river runoff from land.
The main part of the organic matter of the ocean is in a dissolved state and only 3 - 5% is in the form of suspension (Vinogradov A.P., 1967). The concentration of these suspensions in water is low, but their total mass in the entire volume of the ocean is very significant: 120 - 200 billion tons. The annual accumulation of highly dispersed organic detritus in the sediments of the World Ocean, according to V.A. Uspensky, exceeds 0.5109 tons.
Dispersed organic matter sorbs and entrains a certain complex of dispersed elements into sediments. With a certain convention, their content can be judged by the microelement composition of large accumulations of organic matter - deposits of coal and oil. The concentration of elements in these objects is usually given in relation to the ash; Equally important are data relative to the original, unashed material.
As can be seen from Table. 4.2, the microelement composition of coal and oil is fundamentally different.
Table 4.2
Average concentrations of trace metals in coal and oil, 10-4%
| Chemical element | In the dry matter of bituminous coals (W.R. Kler, 1979) | In the ashes of coal (F.Ya. Saprykin, 1975) | In the ashes of oils (K. Krauskopf, 1958) |
| Ti | 1600 | 9200 | - |
| Mn | 155 | - | - |
| Zr | 70 | 480 | 50-500 |
| Zn | 50 | 319 | 100-2500 |
| Cr | 18 | - | 200-3000 |
| V | 17 (10-200) | - | 500-25000 |
| Cu | 11 | - | 200-8000 |
| Pb | 10 | 93 | 50-2000 |
| Ni | 5 | 214 | 1000-45000 |
| Ga | 4,5(0,6-18) | 64 | 3-30 |
| co | 2 | 63 | 100-500 |
| Mo | 2 | 21 | 50-1500 |
| Ag | 1,5 | - | 5 |
| sn | 1,2 | 15 | 20-500 |
| hg | 0,2 | - | - |
| As | - | - | 1500 |
| Ba | - | - | 500-1000 |
| Sr | - | - | 500-1000 |
Oil has a different ratio, a significantly higher concentration of many trace elements. The high content of titanium, manganese and zirconium in hard coals is due to mineral impurities. Among the scattered metals, the highest concentration is typical for zinc, chromium, vanadium, copper and lead.
Organic matter actively accumulates many toxic elements (arsenic, mercury, lead, etc.), which are constantly removed from ocean water. Consequently, dispersed organic matter, like mineral suspensions, plays the role of a global sorbent that regulates the content of trace elements and protects the environment of the World Ocean from dangerous levels of their concentration. The amount of trace elements bound in dispersed organic matter is very significant, given that the mass of matter in sedimentary rocks is hundreds of times greater than the total amount of all deposits of coal, coal shale and oil. According to J. Hunt (1972), N.B. Vassoevich (1973), A.B. Ronova (1976) the total amount of organic matter in sedimentary rocks is (1520)1015 tons.
The masses of scattered elements accumulated in the organic matter of the Earth's sedimentary stratum are measured in many billions of tons.
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General information. The area of the World Ocean is 361 million km/sq. In the northern hemisphere, the World Ocean occupies 61%, and in the southern - 81% of the area of the hemispheres. For convenience, the globe is depicted in the form of so-called maps of the hemispheres. There are maps of the Northern, Southern, Western and Eastern hemispheres, as well as maps of the hemispheres of the oceans and continents (Fig. 7). In the oceanic hemispheres, 95.5% of the area is occupied by water.
World ocean: structure and history of research. The world ocean is one, it is not interrupted anywhere. From any of its points you can get to any other without crossing the land. According to scientists, the term ocean is borrowed from the Phoenicians and translated from ancient Greek means "a great river encircling the Earth."
The term "World Ocean" was introduced by the Russian scientist Yu.M. Shokalsky in 1917. In rare cases, the term "oceanosphere" is used instead of the term "World Ocean".
Map of the hemispheres of graphic discoveries, which cover the oceans from the second half of the 15th century to the first half of the 17th century. Great geographical discoveries are associated with the names of X. Columbus, J. Cabot, Vasco da Gama, F. Magellan, J. Drake, A. Tasman, A. Vespucci and others. its outlines, depth, salinity, temperature, etc.
Purposeful scientific research of the World Ocean began in the 17th century and is associated with the names of J. Cook, I. Krusenstern, Yu. Lisyansky, F. Bellingshausen, N. Lazarev, S. Makarov and others. ship Challenger. The results obtained by the Challenger expedition laid the foundation for a new science - oceanography.
In the 20th century, the study of the World Ocean is carried out on the basis of international cooperation. Since 1920, work has been underway to measure the depths of the oceans. The outstanding French explorer Jean Picard was the first to sink to the bottom of the Mariana Trench in 1960. A lot of interesting information about the World Ocean was collected by the team of the famous French explorer Jacques Yves Cousteau. Space observations provide valuable information about the World Ocean.
The structure of the oceans. The World Ocean, as is known, is conditionally divided into separate oceans, seas, bays and straits. Each ocean is a separate natural complex, due to its geographical location, the peculiarity of the geological structure and the bioorganisms inhabiting it.
The World Ocean in 1650 was first divided by the Dutch scientist B. Varenius into 5 parts, which are currently approved by the International Oceanographic Committee. As part of the World Ocean, 69 seas are distinguished, including 2 on land (Caspian and Aral).
Geological structure. The world ocean consists of large lithospheric plates, which, with the exception of the Pacific, are named after the continents.
River, glacial and biogenic deposits are found at the bottom of the World Ocean. The deposits of active volcanoes, as a rule, are confined to the mid-ocean ridges.
The relief of the bottom of the oceans. The relief of the bottom of the World Ocean, like the land relief, has a complex structure. The bottom of the World Ocean is usually separated from the land by a continental shelf, or shelf. At the bottom of the World Ocean, as well as on land, there are plains, mountain ranges, plateau-like elevations, canyons and depressions. Deep-sea depressions are a landmark of the World Ocean that cannot be found on land.
The mid-ocean ridges, together with the spurs, form a continuous single chain of mountains with a length of 60,000 km. The waters of the land are divided between five basins: the Pacific, Atlantic, Indian, Arctic and Inner closed. For example, rivers flowing into the Pacific Ocean or its constituent seas are called the rivers of the Pacific Basin, and so on.
A. Soatov, A. Abdulkasymov, M. Mirakmalov "Physical geography of continents and oceans" Publishing and printing art house "O`qituvchi" Tashkent-2013