Hydrosphere. World ocean

River basin- the area from which a river and its tributaries collect water. Swamp- an excessively moist area of ​​land with moisture-loving vegetation and a peat layer of at least 0.3 m. The water in swamps is in a bound state. There are two main types of swamps - upland swamps (in which moisture comes only from precipitation and dry out in its absence) and lowland swamps (fed by groundwater or river water, relatively rich in salts). Main reason formation of swamps - excessive moisture in combination with a high level of groundwater due to the close occurrence of water-resistant rocks to the surface and flat terrain.

Watershed- the line dividing the basins of two rivers or oceans, usually passing through elevated areas.

water sushi- part of the hydrosphere, these include groundwater, rivers, lakes, swamps, glaciers.

Unrest- These are predominantly oscillatory movements of water of different nature (wind, tidal, seismic). Common to all types of waves is the oscillatory movement of water particles, in which the mass of water moves around one point.

Geysers- springs that periodically emit fountains of water and steam, which are a manifestation of the late stages of volcanism. Known in Iceland, USA, New Zealand, Kamchatka.

Water shell of the Earth. The total volume of water in the hydrosphere is 1.4 billion km 3, 96.5% of which falls on the World Ocean, 1.7% on groundwater, about 1.8% on glaciers, less than 0.01% on surface water land (rivers, lakes, swamps).

Delta- a low-lying plain in the lower reaches of a river, composed of sediment brought by the river and cut through a network of channels.

Bay- a part of the ocean, sea or lake that cuts into land and has free water exchange with the main part of the reservoir. A small bay, well protected from the wind, is called a bay. A bay separated from the sea by a sand spit, in which there is a narrow strait (often formed at the mouth of a river) - an estuary. In northern Russia, a bay that juts deep into the land into which a river flows is called a gulf. Deep, long bays with winding shores are fjords.

One or several rivers flow from waste lakes (Baikal, Ontario, Victoria). Lakes that do not have a drainage are drainless (Caspian, Mortvoe, Chad). Endorheic lakes are often saline (salt content above 1%). Depending on the degree of salinity, lakes are fresh and salty.

Source- the place where a river originates (for example: a spring, lake, swamp, glacier in the mountains).

Glaciers- natural moving accumulations of ice formed from precipitation above snow line(the level above which snow does not melt). The height of the snow line is determined by temperature, which is related to the latitude of the area and the degree of continental climate, and the amount of solid precipitation. A glacier has a feeding area (i.e., ice accumulation) and an ice melting area. The ice in the glacier, under the influence of gravity, moves from the feeding area to the melting area at a speed of several tens of meters per year (see diagram 1 on p. 76). The total area of ​​glaciers is 11% of the land surface with a volume of 30 million km 3. If all glaciers melted, the level of the world's oceans would rise by 66 m.

Low water- a period of low water level in the river.

World ocean - main part hydrosphere, which accounts for 71% of the globe's area (in the Northern Hemisphere - 61%, in the Southern - 81%). The world ocean is conventionally divided into four oceans: Pacific, Atlantic, Indian, Arctic. Some researchers identify a fifth - the Southern Ocean. It includes water Southern Hemisphere between Antarctica and the southern tips of the continents South America, Africa and Australia.

Permafrost- rocks in the upper part of the earth's crust that remain permanently frozen or thaw only in the summer. Emergence permafrost occurs in conditions of very low temperatures and low altitude snow cover. The thickness of the permafrost layer can reach 600 m. The area of ​​permafrost in the world is 35 million km2, including 10 million km2 in Russia.

Sea- a part of the ocean, more or less separated by islands, peninsulas or underwater hills, characterized by a special hydrological regime. There are seas internal- protruding deeply into the continent (Mediterranean, Baltic) and outlying- adjacent to the mainland and slightly isolated from the ocean (Okhotsk, Beringovo).

Lake- a reservoir of slow water exchange, located in a closed natural depression (basin) of the land surface. Based on their origin, lake basins are divided into tectonic, volcanic, dam, glacial, karst, floodplain (oxbow lakes), and estuary. By water regime a distinction is made between waste and non-waste (Table 1, p. 76).

Flood- short-term, irregular rise in water level.

Groundwater- waters contained in the upper (12-16 km) thickness of the earth’s crust in liquid, solid and gaseous states. The possibility of water being found in the earth's crust is determined by the porosity of rocks. Permeable rocks (gravel, pebbles, sands) allow water to pass through well. Water-resistant rocks are fine-grained, weakly or completely impervious to water (clays, granites, basalts). According to the conditions of occurrence, groundwater is divided into soil (water in a bound state in the soil), groundwater (the first permanent aquifer from the surface, lying on the first waterproof horizon), interstratal water (confined between waterproof horizons), including artesian (pressure interstratal ).

Floodplain- part of a river valley that is flooded during high water and floods. The slopes of the valley usually rise above the floodplain, often in stepped shapes - terraces.

High water- annually recurring period high level water in the river caused by the main food source. Types of river feeding: rain, snow, glacial, underground.

Strait- a relatively narrow body of water that separates two land areas and connects adjacent water basins or parts thereof. The deepest and widest strait is the Drake Strait, the longest is the Mozambique Strait.

River mode- regular changes in the state of the river, due to the physical and geographical properties of its basin and climatic features.

River- a constant water flow flowing in a depression he himself developed - a channel.

river valley- a depression in the relief at the bottom of which a river flows.

River system- a river with its tributaries. The name of the river system is given by main river. The largest river systems world - Amazon, Congo, Mississippi and Missouri, Ob and Irtysh.

Salinity of sea water- the amount of salts in grams dissolved in 1 kg (l) of sea water. The average salinity of water in the ocean is 35%o, the maximum - up to 42%o - in the Red Sea.

Water temperature in the ocean depends on the amount of solar heat reaching its surface. The average annual temperature of surface waters is 17.5°; at a depth of 3000-4000 m it usually ranges from +2° to 0°C.

Currents- translational movements of water masses in the ocean, arising under the influence various forces. Currents can also be classified by temperature (warm, cold and neutral), by time of existence (short-term, periodic and permanent), depending on depth (surface, deep and bottom).

Estuary- the place where a river flows into a sea, lake or other river.

Estuary- a funnel-shaped flooded mouth of a river, expanding towards the sea. It is formed near rivers flowing into seas, where the influence of ocean water movements (tides, waves, currents) on the river mouth is strong.

Hydrosphere - the totality of all the waters of the Earth: continental (deep, soil, surface), oceanic and atmospheric. Sometimes the waters of oceans and seas are combined into a peculiar part of the hydrosphere - oceanosphere. This is logical, because the vast majority of water is concentrated in the oceans and seas.

The appearance of water on Earth is usually associated with the condensation of water vapor from volcanic eruptions that have occurred since the formation of the planet. Evidence of the presence of water in the geological past is sedimentary rocks that have horizontal layering, which reflects the uneven deposition of mineral particles in aquatic environment. Such rocks are known and their age dates back to 3.8-4.1 billion years. However, the appearance of droplet water could have happened earlier - in the air, on the surface of the planet, in the voids of rocks. So that water can concentrate in depressions earth's surface and form basins, watering of initially dehydrated rocks should have occurred. The primary waters were highly mineralized, which is associated with the dissolution of various substances in them that were released along with water vapor during volcanic manifestations. Fresh waters appeared later. It's possible that additional source there were waters on earth ice comets, invading the atmosphere. This process is still observed today, as is the formation of water during the condensation of vapor from volcanic eruptions.

Despite the diversity natural waters and their different states of aggregation, the hydrosphere is one, for all its parts are connected by the flows of oceanic and sea ​​currents, channel, surface and underground runoff, as well as atmospheric transport. The structural parts of the hydrosphere are given in Table. 5.3.

Physicochemical properties of water. Water is the most amazing substance in the world. Despite the fact that A. Celsius used for temperature scale The melting point of water is 0° and its boiling point is 100°, this liquid can freeze at a temperature of 100 ° C and remain liquid at -68 ° C depending on the oxygen content and atmospheric pressure. It has many anomalous properties.

Fresh water is odorless, colorless and tasteless, whereas sea water is tasteful, colorless and may have an odor. Under natural conditions, only water occurs in three states of aggregation: solid (ice), liquid (water) and gaseous (water vapor).

The presence of salts in water changes its phase transformations. Fresh water on the surface of land at a pressure of one atmosphere has a freezing point of 0°C and a boiling point of 100°C. Sea water at a pressure of one atmosphere and a salinity of 35‰ has a freezing point of about -1.9°C and a boiling point of 100.55°C. The boiling point depends on atmospheric pressure: than more height above the ground, the smaller it is. Water is a universal solvent: it dissolves more salts and other substances than any other substance. It is a chemically stable substance that is difficult to oxidize, burn, or decompose into its constituent parts. Water oxidizes almost all metals and destroys even the most resistant rocks.

Table 5.3 Volume of water and water exchange activity of various parts of the hydrosphere

When water freezes, it expands, increasing its volume by about 10%. The density of fresh water is 1.0 g/cm3, sea water is 1.028 g/cm3 (at a salinity of 35‰), fresh ice- 0.91 g/cm3 (this is why ice floats in water). The density of other bodies (except bismuth and gallium) increases during the transition from a liquid to a solid state. Water has a high specific heat capacity, i.e. ability to absorb large number heat and heat up relatively little. This property is extremely important, since water stabilizes the planet’s climate.

The anomalous properties of water are explained by the structure of its molecule: hydrogen atoms are attached to the oxygen atom not “classically”, but at an angle of 105°. Due to asymmetry, one side of the water molecule has positive charge, and the other is negative. Therefore, a water molecule represents an electric dipole.

The processes in which water is involved are extremely multifaceted: photosynthesis of plants and the respiration of organisms, the activity of bacteria and organisms that generate from water (mainly sea water) to build their skeletons or accumulate chemical elements (Ca, J, Co), nutritional processes and anthropogenic pollution and many others.

World ocean (oceanosphere)- single continuous water shell Earth, which includes oceans and seas. Currently, there are five oceans: Pacific, Atlantic, Indian, Arctic (Arctic according to foreign classifications) and Southern (Antarctic). According to the international classification, there are 54 seas, among which are: internal And outlying.

The volume of waters of the World Ocean is 1340-1370 million km3. The volume of land rising above sea level is 1/18 of the volume of the ocean. If the surface of the Earth were completely flat, the ocean would cover it with a layer of water of 2700 m.

The waters of the World Ocean make up 96.5% of the volume of the hydrosphere and cover 70.8% of the planet's surface (362 million km2). Thanks to the huge mass of water, the World Ocean has great influence on the thermal regime of the earth's surface, performing the functions of a planetary thermostat.

Chemical composition of the waters of the World Ocean. Sea water is a special type of natural water. The formula of water H2O is also true for sea water. However, in addition to hydrogen and oxygen in sea ​​water contains 81 of 92 naturally occurring elements (theoretically, all naturally occurring elements of the periodic table can be found in seawater). Most of them are found in extremely low concentrations.

1 km3 of sea water contains about 40 tons of dissolved solids, which define it most important property - salinity. Salinity is expressed in ppm (0.1%) and its average value for ocean waters it is 35‰ . Water temperature and salinity determine density sea ​​water.

The main ones that make up sea water are given below.

1. Solids, averaging 3.5% (by weight). Sea water contains the most chlorine (1.9%), i.e. more than 50% of all dissolved solids. This is followed by: sodium (1.06%), magnesium (0.13%), sulfur (0.088%), calcium (0.040%), potassium (0.038%), bromine (0.0065%), carbon (0.003%) . The main elements dissolved in sea water form compounds, the main of which are: a) chlorides(NaCl, MgCl) - 88.7%, which gives sea water a bitter-salty taste; b) sulfates(MgSO4, CaSO4, K2SO4) - 10.8%; V) carbonates(CaCO3) - 0.3%. In fresh water, on the contrary: the most carbonates (60.1%) and the least chlorides (5.2%).

2. Nutrients(nutrients) - phosphorus, silicon, nitrogen, etc.

3. Gases. Sea water contains all atmospheric gases, but in a different proportion than in air: nitrogen predominates (63%), which, due to its inertness, does not participate in biological processes. Next come: oxygen (about 34%) and carbon dioxide(about 3%), argon and helium are present. In those marine areas where there is no oxygen (for example, in the Black Sea), hydrogen sulfide is formed, which is absent in the atmosphere under normal conditions.

4. Microelements present in low concentrations.

Geographic patterns of distribution of water temperature and salinity. General patterns of horizontal (latitudinal) distribution of temperature and salinity on the surface of the World Ocean are shown in Fig. 5.9 and 5.10. It is obvious that water temperature decreases in the direction from the equator to the poles, and salinity is characterized by a pronounced minimum in the equatorial region, two maximums in tropical latitudes and lower values ​​at the poles. The alternation of centers of low and high salinity near the equator and in the tropics is explained by the abundance of precipitation in the equatorial zone and the excess of evaporation over precipitation in the northern and southern tropics.

The water temperature decreases with depth, as can be seen in Fig. 5.11 for the North Pacific. This pattern is characteristic of the World Ocean as a whole, however, changes in water temperature and salinity differ in its separate parts, which can be explained by a number of reasons (for example, the time of year). Biggest changes occur in the upper layer to a depth of 50-100 m. With depth, the differences disappear.

Water masses- this is a large volume of water that forms in a certain area of ​​the World Ocean and has relatively constant physical, chemical and biological properties.

According to V.N. Stepanov (1982), the following water masses are distinguished vertically: superficial, intermediate, deep And bottom

Among the surface water masses there are equatorial, tropical(northern and southern), subtropical(northern and southern), subpolar(subarctic and subantarctic) and polar(Arctic and Antarctic) water masses (Fig. 5.12).

Borders various types water masses are boundary layers: hydrological fronts, zones divergences(discrepancies) or convergence(convergence) water.

Surface water interacts most actively with the atmosphere. In the surface layer, intense mixing of water occurs; it is rich in oxygen, carbon dioxide and living organisms. They can be called the waters of the “oceanic troposphere”.

Along with surface currents(see Fig. 7.11) in the World Ocean there are countercurrents, subsurface and deep water movements, as well as vertical mixing, tidal currents, and level fluctuations.

Rice. 5.9. Average annual temperature (°C) of the surface of the World Ocean (according to V.N. Stepanov 1982): 1 - isotherms; 2 - areas maximum temperature water; 3 - areas of water temperature below average ( average temperature water 18.56°С)

Rice. 5.10. Average annual salinity (‰) of the surface of the World Ocean (according to V.N. Stepanov, 1982): 1 - isohalines; 2 - areas of maximum salinity; 3 - areas of salinity below average; 4 - areas of minimum salinity (average salinity value 34.7 8‰)

Rice. 5.11. Graphs of vertical temperature distribution, typical for arctic (1), subarctic (2), subtropical (3), tropical (4) and equatorial (5) types of waters

Relief of the bottom of the World Ocean. The following structures are distinguished in the relief of the bottom of the World Ocean: shelf(continental shelf), usually limited by an isobath of 200 m, continental(continental) slope to a depth of 2000-3000 m and ocean bed. According to another classification, there are: littoral(And sublittoral), bathyal, abyssal(Fig. 5.13). Plots With depths greater than 6000 m constitute no more than 2% of the area of ​​the ocean floor; depths less than 200 m constitute approximately 7%.

Rice. 5.12. Ocean fronts and surface water masses of the World Ocean (according to V.N. Stepanov, 1982): types of water masses: Ar- arctic; SbAr- subarctic; SbTs - subtropical Northern Hemisphere; Ts- tropical Northern Hemisphere; E- equatorial; Ty - tropical Southern Hemisphere; SbTu- subtropical Southern Hemisphere; SbAn - subantarctic; An - Antarctic; Tar- Arabian Sea; 715 - Bay of Bengal. The names of the ocean fronts are indicated in the figure.

Rice. 5.13. Schematic subdivision of the ocean floor

The role of the oceanosphere. Various (thermal, mechanical, physical, chemical, etc.) processes occurring on the vast (more than 70% of the Earth's surface) water area of ​​the World Ocean have a significant impact on the processes occurring on land and in the atmosphere. Chemical elements, which are part of sea water, participate in the processes of gas, mass and moisture exchange at the boundaries of the hydrosphere - lithosphere - atmosphere. Hydrochemical processes affect animals and flora not only the ocean, but the planet as a whole. Constant gas exchange with the atmosphere regulates the gas balance of the Earth: the carbon dioxide content in seawater is 60 times higher than in the atmosphere.

land waters, Despite their relatively small volume, they play a huge role in the functioning of the geographical envelope and the life of organisms. It should be noted that not all land waters are fresh; there are salt lakes and springs. The ionic composition of fresh and sea water is given in table. 5.4.

Rivers- the most active representative of fresh waters on land. Rivers include permanent and relatively large watercourses. Smaller streams are called streams. Relief, geological structure, climate, soil, vegetation influence the regime of rivers and shape their natural appearance. The river has source - the place where it starts, and mouth- the place where a river directly flows into a receiving body of water (lake, sea, river). The mouth can branch, forming delta rivers. The area of ​​land through which a river flows is called along the riverbed The main river and its tributaries install a river system. Rivers flowing into the World Ocean form estuaries- vast spaces of mixing river and sea water. Estuaries are largely influenced by ocean waters.

Table 5.4. Ionic composition of river and sea water (according to P. Weil, 1977)

The nature of river flow is related to their food, which can be rain, snow, glacial and underground, and is determined climatic conditions in the river basin. Rivers predominantly snow-fed have pronounced spring floods and summer low water (Volga, Dnieper, Danube, Northern Dvina, Amur, etc.). Underground feeding smooths out annual flow. In rain-fed rivers, the maximum flow often occurs in different seasons of the year. The areas of the earth's surface and the thickness of soils and soils from which the river receives its nutrition are called catchment area

Rivers do significant work, eroding the bed, transporting and depositing erosion products - alluvium. They not only mechanically destroy, but also dissolve rocks. River deposits sometimes form vast alluvial plains with an area of ​​millions of kilometers (Amazonian, West Siberian lowlands, etc.). It is estimated that rivers hold 2,100 km3 of water at any one time, while 47,000 km3 flows into the ocean annually. This means that the volume of water in the rivers is renewed approximately every 16 days. For comparison, we point out that the waters of the World Ocean carry out great gyre in about 2500 years.

Lakes- a natural body of water on land with slow water exchange, which does not have a direct connection with the ocean. For its formation, the presence of a closed depression of the earth's surface (basin) is necessary. The lakes occupy a total area of ​​approximately 2 million km2, and the total volume of their water exceeds 176 thousand km3. According to the conditions of formation of the basin, size, chemical composition of water, thermal regime The lakes are very diverse. A lot of artificial lakes have been created - reservoirs(about 30 thousand), the volume of water in which is more than 5 thousand km3. Approximately half of the lake waters are salty, and most of them are concentrated in the largest closed lake - the Caspian Sea (76 thousand km3). The largest freshwater lakes are Baikal (23 thousand km3), Tanganyika (18.9 thousand km3), Verkhnee (16.6 thousand km3). The regime of lakes is characterized by heat influx, fluctuations in water level, currents, water exchange conditions, ice cover, etc. Large lakes largely determine the climatic conditions of adjacent territories (for example, Lake Ladoga).

Swamps- these are areas of land characterized by excessive moisture, stagnant or weakly flowing water regimes and hydrophytic vegetation. They occupy an area of ​​2.7 × 106 km2, or about 2% of the land surface. The volume of marsh waters in the world is about 11.5 km3, which is 5 times greater than the one-time volume of water in rivers. The occurrence of swamps is associated both with climatic conditions (excess moisture) and with geological structure territories (proximity to an impermeable horizon) that contribute to swamping of land or overgrowing of water bodies. In some areas of temperate and subpolar latitudes, permafrost plays the role of aquifer. A specific formation of swamps is peat.

Groundwater- These are waters found in rocks in a liquid, solid or gaseous state. According to latest research, the water content in rocks within the lithosphere exceeds the data indicated in table. 5.3, and is about 0.73 - 0.84 billion km3. This is only half as much as is contained in the seas, oceans and surface waters, including the world's ice reserves. Water accumulates in all sorts of voids - channels, cracks, pores. It has been established that below the groundwater level to a depth of 4 - 5 km or more, almost all the voids in the rocks are filled with water. According to deep drilling data, water in the voids of rocks is located at a depth of more than 9.5 km, i.e. below the average level of the bottom of the World Ocean.

A set of watercourses (rivers, streams, canals), reservoirs (lakes, reservoirs) and others water bodies(swamps, glaciers) is hydrographic network.

Land waters have been greatly transformed by humans due to irrigation, land reclamation, plowing and other urban processes, and therefore the problem of drinking water has become acute.

The difficulty of solving it lies in the fact that the needs for clean water grow, but its reserves remain the same. Used V in everyday life, in industrial and agricultural cycles, fresh water most often returns to river network in the form of wastewater, treated differently or not treated at all.

Water shell of the Earth. It includes all the water on Earth in liquid, solid and gaseous states. The hydrosphere consists of several parts.

Main parts of the Earth's hydrosphere Their ratio, %
World Ocean 96.4
Glaciers of the Earth 1.8
Groundwater 1.7
Rivers, lakes, swamps 0.01
The world's oceans occupy about 71% of the surface of our planet. It is divided by continents into four oceans: the Pacific, Atlantic, Indian and Arctic. Some scientists identify a fifth ocean - the Southern Ocean. The largest and deepest of them is Quiet. All oceans have seas, bays, and straits.
Seas- these are parts of the oceans, more or less separated from them by land or underwater rapids, bottom rises. The Baltic Sea, for example, is part of the Atlantic Ocean, and the Red Sea is part of the Indian Ocean.
Those seas that protrude slightly into the land are called marginal (Barents, Kara). But there are seas that extend far into the land; They are connected to the oceans by straits. Such seas are called marginal seas (Mediterranean, Baltic).
A bay is a part of the ocean, sea or lake that juts out into the land, gradually decreasing in width and depth. The Atlantic Ocean off the coast of Europe forms the Bay of Biscay, and the Indian Ocean, jutting into land in the south of Eurasia, forms the Bay of Bengal.
Relief of the bottom of the World Ocean. Along the coasts of the continents stretches their underwater outskirts - the continental shoal, or shelf. Its depth does not exceed 200 m, and its width can be different. Shelf - the most important place fishing for fish and other seafood, as well as minerals: oil and gas. The sea shelf at a distance of 200 miles is considered the territory of the coastal state and its property.
From a depth of 200 to 2500 m, the continental slope goes down quite steeply, which gradually turns into the ocean floor. The ocean bed, like land, has flat areas, mountains, the peaks of which sometimes protrude above the surface of the ocean in the form of islands, as well as depressions - deep ocean trenches.
The depths of the World Ocean are measured using a special device - an echo sounder. In 1957, this instrument measured the deepest depression in Pacific Ocean- Mariana Trench (11,022 m).
Irregularities in the bottom of oceans and seas are depicted on physical maps layer-by-layer painting (various shades blue) and depth marks.
Bottom sediments. The bottom of the oceans and seas is covered with marine sediments. By origin, these sediments are of two types: continental, that is, washed away from the land (sand, clay, pebbles), and oceanic, which are formed as a result of the death of marine organisms. Ocean sediment accumulates at the bottom in the form of silt. Accumulation occurs very slowly.
Water temperature The temperature of water at the surface of the ocean depends on climate (it decreases from the equator to the poles), as well as on powerful currents, which can violate this pattern. With depth, for every 1000 m, the water becomes colder by 2 °C. At the bottom of deep-sea depressions, the water temperature is about 0 °C.
Ocean salinity. In all seas and oceans, water has a bitter-salty taste. On average, every liter of sea water contains 35 g of salt. The water of inland seas differs in salinity and temperature from the water of the oceans: in the seas of the hot zone there is increased temperature and salinity, and in the seas temperate zone, taking in a large runoff river waters, salinity is much lower.
Ice in the World Ocean. The freezing point of salty ocean water is 1-2 °C lower than that of fresh water. The waters of the World Ocean are covered with ice only in the polar regions. Ocean ice can be stationary (land-bound) or mobile (drift ice in the North Arctic Ocean).
In addition to ice formed in the ocean itself, there is ice that has broken off from ice sheet sushi. Such “suppliers” of ice can be the polar islands, the island of Greenland and, of course, the “ice” continent of Antarctica. Icebergs (from the Dutch ice - ice, berg - mountain) of Antarctica sometimes reach 150 m in length. Typically, the main part of an iceberg is under water; it rises 70-100 m above the surface. Currents move icebergs across the World Ocean, where they gradually melt.
Movement of water in the ocean. Waves. How are waves formed on the surface of the oceans? Under the influence of the wind. Its gusts seem to press the surface of the ocean, forming waves up to several meters high.
Ocean currents. Water in the world's oceans moves. Horizontal movements of masses of water in the ocean in the form of huge streams moving along certain permanent paths(a kind of river in the ocean) are called ocean currents. They are formed mainly under the influence of constant winds, which force water to move in a certain direction. One of the largest ocean currents on the globe begins off the coast of North America in Atlantic Ocean and is called the Gulf Stream. Gulf Stream- warm current: its temperature is higher than the temperature surrounding water. There are also cold currents in the ocean, such as the Labrador Current. The directions of warm ocean currents on maps are indicated by red arrows, and cold ones by blue or black arrows. Ocean currents greatly influence the climate of coastal land areas.
The flora and fauna of the oceans and seas are rich and diverse; the largest animals on the globe - whales - live in the water, as well as thousands of species of fish, seaweed and plankton - the smallest plant and animal organisms. These organisms contain many nutrients and are food for whales and other marine life.
The seas of the Arctic Ocean are home to seals and walruses. Fur seals live on islands in the Bering Sea.
Mineral wealth of the World Ocean. Sea water can be called liquid ore, since many substances that are widely used by humans are dissolved in it - table salt, magnesium, bromine and others.
Huge reserves of oil and gas are hidden in the depths of the seabed. People have not yet learned how to use these riches intensively enough.
Shipping. Sea channels. Every year more and more different cargoes are transported across the seas and oceans. The Suez and Panama canals are important for shipping. The first was built in 1869 and made possible the sea route from the Mediterranean Sea to the Indian Ocean. The Panama Canal was officially opened to shipping in 1920 and shortened the route between the eastern and the west coasts North America. Sea routes to geographical maps are indicated by blue dotted lines, and sea port cities are marked symbol- anchor.
Modern methods of studying the oceans and seas. Great value Expeditionary vessels equipped with special equipment, in particular for studying the ocean floor, play a role in ocean exploration.
In the Arctic Ocean, scientists monitor the salinity and temperature of water, the direction and speed of currents, and the depth of the ocean from drifting stations.
The study of the depths of the World Ocean is carried out using a variety of underwater vehicles: bathyscaphes, submarines etc.
Observations of ocean currents, waves and drifting ice are also carried out from space.
Ocean waters need protection from pollution, and many animals need protection from destruction. The main pollutant of ocean waters is oil; it enters the water during its extraction from the bottom of the seas, during loading and unloading of oil tankers, and also as a result of accidents of oil tankers. Burials are also dangerous radioactive substances at the bottom of the ocean.

The hydrosphere is located between the earth's crust and the atmosphere and is a collection of oceans, seas, surface waters, ice and snow. Sometimes the hydrosphere also includes groundwater and water contained in the atmosphere and living organisms (Table II. H).

The vast majority of water is concentrated in the oceans. Other water bodies include groundwater and glaciers. The bulk of fresh water, which represents the most important part of humanity’s water resources, is concentrated in underground horizons and glaciers. The volume of groundwater, especially in the lower parts of the earth's crust, is estimated approximately.

Despite the variety of types of water, the hydrosphere is united. Its unity is connected both with common origin of all waters (came from the Earth's mantle), and with continuous exchange between reservoirs.

World ocean. The waters of the World Ocean make up 96.5% of the mass of water in the hydrosphere. They cover most of the planet's surface (70.8%), forming an almost continuous water shell of the Earth. The World Ocean is the most important link in moisture circulation in the system of interaction “ocean - atmosphere - continents”. It has an extremely large influence on the thermal regime of the earth's surface, performing the functions of a planetary heater and thermostat.

The United World Ocean has historically been divided into separate parts - oceans. Their morphometric indicators are given in table. II.2. Inside the oceans there are smaller parts: seas, bays, straits, estuaries, etc.

Sea water. The world's oceans are called a large sedimentation basin because they accumulate various substances, coming from land. Almost all elements of the periodic table are present in sea water, but the concentration various elements not the same. The average salinity of the World Ocean is about 35%o, i.e. 1000 kg of sea water contains 35 kg of salts. The overwhelming majority of salts are sodium and magnesium chlorides (88.7%). Second place is occupied by sulfates (10.8%), then carbonates (0.3%) and other compounds. The distribution of salinity in surface waters (Figure II.6) is largely zonal. It reflects the structure of the water balance in different parts of the World Ocean. The maximum salinity (more than 36% o) is observed in tropical and partially subtropical regions, i.e., where evaporation is most significant and at the same time there is relatively little precipitation. That is why, in general, the distribution of salinity corresponds to the isolines of the map (see Fig. III.14), which shows the distribution of the difference between evaporation and precipitation on the oceans. In the equatorial zone there is a slight decrease in salinity. In yet to a greater extent salinity decreases in temperate, subpolar and polar regions.

General zonal patterns of salinity distribution are complicated by the influence of regional factors. The Atlantic Ocean has higher salinity than other oceans. In the Arctic, it is lower under the influence of ice cover, in the Indian and Pacific - due to an increase in the amount of precipitation falling over them.

In inland seas, salinity depends largely on the amount of incoming water. river flow and on the intensity of water exchange with open ocean. Salinity is low, for example, in the Baltic Sea (8% o). The salinity in the Black Sea is significantly lower than the average salinity of the ocean - 17-18%. But in the Red Sea it rises to 40%. This is explained by the very large evaporation from the surface of the Red Sea under conditions of strong heating and the virtual absence of river flow in this area.

Below a depth of 2000 m, the salinity of all oceans is close to 34.7-34.9%o, that is, in low latitudes it is less than at the surface, in polar latitudes it is higher.

Gases are also dissolved in the water of oceans and seas, the most important of which are oxygen and carbon dioxide (carbon dioxide). There is a constant exchange of gases between the ocean and the atmosphere, so that the ocean acts as a regulator of their content in the atmosphere.

The density of sea water is important, the average value of which is 1.025 g/cm3. As already mentioned, salty sea water has its maximum density at its freezing temperature. Therefore, the cooled seawater sinks down. If there were no flow of fresh water into the oceans, the oceans would never be covered with ice.

Oceanic water masses. A relatively large volume of water that forms in certain areas of the World Ocean, has relatively constant physical, chemical and biological characteristics and forms a single complex (natural aquatic), is called oceanic water mass. Water masses in the oceans are analogues of natural territorial complexes on land. The boundaries between water masses in the ocean are less clearly defined than the boundaries of natural territorial complexes on land. Vertically, there are four main water masses or structural zones: surface, intermediate, deep and bottom.

The surface structural zone extends to approximately depths of 300 m. The waters of this zone actively interact with the atmosphere. This layer is sometimes called the oceanic troposphere by analogy with the atmospheric troposphere. Active mixing of water occurs in the surface layer; it is rich in oxygen and carbon dioxide, organisms. His physical characteristics and salinity are subject to fluctuations due to atmospheric influences. Surface waters are captured by currents that form specific gyres (see III. 2.3).

Surface waters are divided horizontally by oceanic fronts into water masses. Highlight following types water masses in the surface structural zone.

1. Equatorial with water temperature 26-28 °C, salinity 33-35%o, oxygen content 3-4 g/m3 and relatively low saturation life forms.

2. Tropical, divided into north tropical and south tropical, with water temperatures from 18 to 27 ° C, salinity 34.5-35.5%o, oxygen content 2-4 g/m3.

3. Subtropical, subdivided into northern and southern subtropical, with temperatures from 15 to 28 ° C, salinity from 35 to 37%o, oxygen content 4-5 g/m3.

4. Subpolar, subdivided into subarctic and subantarctic, with temperatures from 5 to 20 °C, salinity 34-35%o, oxygen content 4-6 g/m3. They are very rich in life forms: fish, mammals (whales, seals, etc.). It is in these water masses that the main fishing areas are located.

5. Polar, including Arctic and Antarctic water masses, with low temperatures (from 5 to -1.8 ° C), with low salinity (32-34%o), very rich in oxygen (5-7 g/m3). Most of the year they are covered with ice, but nevertheless they are rich in life, especially in contact zones (rocky shores, ice edges, etc.).

Natural features of the listed water masses in to a large extent are determined by the features of vertical circulation, which will be discussed below.

The transitional, or intermediate, structural zone is located at depths from 300 to 2000 m. In the polar regions, the waters of this zone are characterized by relatively high temperature, since from the surface it is covered by approximately a hundred-meter layer of the surface zone, which has a low temperature and low salinity.

Deep water masses occupy most of the ocean's volume. They are characterized by a low temperature (2-3°C), the absence of seasonal fluctuations, and also seasonal changes salinity, oxygen content and other characteristics that are subject to seasonal variability in the overlying water masses.

Bottom waters fill the deepest parts of the ocean. Like deep water masses, they are formed as a result of the subsidence of cold polar surface water masses. In the bottom waters there is a slight increase in temperature (by about 0.1 °C). This increase is associated with the flow of heat from the depths.

Ocean fronts that form in zones of contact and interaction of various water masses are distinguished by vortex movements of water - cyclonic and anticyclonic, accumulation of life, and active interaction with the atmosphere. They are dynamic and unstable. Only some of them are confined to certain areas.

Surface waters of land. They are represented by rivers, lakes and swamp waters and make up only 0.014% of the world's water reserves. Despite their insignificant percentage in the world's water reserves, they play a significant role in natural processes flowing in geographical envelope.

Rivers. The most active element of this group of waters are rivers. In river beds there is approximately 2,100 km3 of water at a time, while 47,000 km3 flows into the ocean per year. This means that the volume of water in the rivers is renewed approximately every 16 days. This is the intensity of water exchange in rivers. For comparison, let us point out that ocean waters pass through a large cycle in about 2.5 thousand years.

The most important characteristic of rivers (along with flow) is their nutrition. Rivers with snow, rain, glacial and underground feeding are distinguished. More or less significant rivers, as a rule, have mixed nutrition, including rain and underground, and often snow and glacial. This depends on the size of the basin and the diversity of its landscapes. An essential element of river nutrition is groundwater, which ensures the constant water flow of rivers. As a result, they account for up to 30% of the total river flow each year.

The annual flow of rivers is closely related to their nutrition. Thus, rivers predominantly snow-fed have pronounced spring floods and summer low water (rivers of the European part of the USSR). Glacially fed rivers are characterized by predominantly summer flow, since during this season of the year snow and glaciers in the mountains (Amu Darya, Syrdarya, Kuban, Terek, etc.) melt especially intensively. The runoff in rain-fed rivers depends on the timing of predominant precipitation: it can be summer (in areas of monsoon climate), winter (in Mediterranean areas), and can be uniform throughout the year (rivers of Western Europe). Consequently, river flow is largely determined by climatic conditions in river basins. This gave grounds to climatologist A.I. Voeikov to conclude that “rivers are a product of climate.”

Flowing river waters have kinetic energy and produce significant work, eroding the riverbed and transporting erosion products - alluvium. River deposits form alluvial plains, for example, the Amazon, West Siberian, East China, Congo, etc. They form deltas at river mouths (Nile, Lena, Volga, Parana) and river terraces on valley slopes.

River waters not only mechanically destroy, but also dissolve rocks, and then transport and accumulate substances in the form of ions, colloids, nutrients, microelements, etc. About 1.6-1012-1.7-1012 kg of dissolved substances are carried into the ocean annually substances, including 0.72-1011 kg of organic substances.

IN modern era there is contamination of surface waters with organic and inorganic substances industrial and agricultural origin, mineral fertilizers. As a result, some lakes are eutrophicated, that is, they are rapidly overgrown with algae (mainly blue-green), which receive abundant nutrition in the form of these pollutants. Pollution of surface waters with petroleum products, chemical waste, and plant protection products is dangerous.

Noteworthy difference chemical composition salts dissolved in sea and river waters. If chlorides and sulfates predominate in ocean waters with an insignificant participation of carbonates, then in rivers carbonates absolutely dominate (up to 60% of the mass of salts). There are only 0.3% of them in sea water.

Lakes. The role of lakes in the geographic environment is quite important and diverse. First of all, they are regulators of river flow, especially in rivers flowing from lakes. Lakes often serve as large accumulators of fresh water: Baikal - 23-1012 m3, Tanganyika - 18.9-1012 m3, Verkhnee - 16.6-1012 m3, etc. The lakes contain reserves of valuable fish species, etc. Minerals are mined in some lakes .

Lakes play a significant role in the water balance of land surface waters. The total area occupied by them is estimated at approximately 2 million km2 with a total volume of water over 1.76X 1014 m3. This is four times the total annual flow of all the world's rivers. Freshwater lakes contain about half of the total volume of lake water (0.91–1014 m3).

Humanity has created (almost exclusively in the second half of the 20th century) a large number (about 10 thousand) of artificial lakes. Currently, the reservoirs have a total water volume of about 5-1012 m3. Largest quantity large reservoirs created in the USSR, as well as in the USA, Canada, China, India and other countries. They have water regulation, reclamation, shipping, fishery and other meanings and functions. In addition to large reservoirs, large number(hundreds of thousands) of ponds of water and fishery importance.

Swamps. These are areas of land characterized by sharply excessive moisture, stagnant or weakly flowing water regimes and specific hygrophytic vegetation. The total area of ​​wetlands on the globe is about 2.7-106 km2, which is about 2% of the land area. The total volume of marsh waters in the world is about 11.5X X 109 m3. This is 5 times the one-time volume of water in river beds. Swamps serve as accumulators of atmospheric, river, and groundwater. Slowly releasing these waters into the river, they thereby regulate the low-water flow.

Groundwater. They are found in the rocks of the upper part of the earth's crust in liquid, solid and vapor states. Based on their origin, the following types of groundwater are distinguished: infiltration, formed as a result of seepage from the surface of rain, melt and river waters; condensation, arising in the pores and cracks of rocks from water vapor; sedimentation, formed in the process of geological sedimentation in aquatic conditions; magmatic, or juvenile, formed during crystallization of magma and metamorphization of rocks. It is believed that most hydrosphere waters occurred due to degassing of magma.

By physical condition There are seven types of groundwater. 1. Gravitational waters. They move under the influence of gravity, fill cracks and voids in the earth's crust, move along them, and also occupy closed depressions on the earth's surface, forming oceans, seas, and lakes.

1. Capillary waters. They fill small pores in soil and rocks and are held in place by forces surface tension and move depending on the gradient of temperature and humidity of the rock, even against the gradient of gravity (due to this, in particular, groundwater flows to the surface). Gravity and capillary waters actively participate in moisture circulation.

3. Film water. It envelops soil particles and is attracted to them by the force of surface tension, therefore it weakly participates in moisture circulation and is poorly used by plants.

4. Hygroscopic water. It envelops small soil aggregates and is removed only with strong heating.

5. Water of crystallization is physically bound in minerals (gypsum, etc.), therefore, when it is removed, their physical properties change.

6. Constitutional water. It is chemically bound in minerals in such a way that when it is removed, the minerals are destroyed.

Based on the nature of the filling of rocks, groundwater is divided into the following types: pore water, filling sands, pebbles and other loose rocks; fissures, or veins, - in rocks (granites, sandstones, etc.); karst - in soluble rocks - limestone, dolomite, gypsum, rock and potassium salts, etc.

A certain stratification (layering) is also observed in groundwater. The first permanently existing unconfined horizon from the earth's surface is called groundwater. Groundwater that lies below groundwater and is separated from it by layers of impermeable rocks is called interstratal. They are usually under hydrostatic pressure and in this case they are called pressure or artesian.

Groundwater is usually fresh (salt content up to 1 g/l) and belongs to the zone of active water exchange with surface waters and, above all, riverine, since rivers drain this horizon, interacting with it. Groundwater most fully reflects natural features territories. The thickness of the groundwater zone can reach 100 m.

Interstratal and fissure waters to approximately a depth of 200-300 m belong to the zone of relatively active water exchange. In this zone, groundwater is partially discharged into deep river valleys and the ocean. They are mostly fresh or slightly mineralized (can contain up to 10 g/l of salts).

The zone of slow water exchange is located below sea level. Its underground waters are discharged only into the ocean. They are predominantly salted (up to 50 g/l), and sometimes are brines (over 50 g/l).