Physical and chemical properties of water in the world's oceans. Physical and chemical properties of the world's ocean waters Physicochemical properties of the world's ocean waters

The oceans represent the main part of the hydrosphere - the water shell of the Earth. Its waters cover 361 million km2, or 70.8%, of the earth's surface, which is almost 2.5 times the land area (149 million km2, or 29.2%). The most important consequence of such a global ratio of land and sea is the influence of the World Ocean on the water and heat balance of the Earth. About 10% of the solar radiation absorbed by the ocean's surface is spent on heating and turbulent heat exchange between the surface layers of water and the lower atmosphere. The remaining 90% of the heat is spent on evaporation. Evaporation from the ocean surface is both the main source of water in the global hydrological cycle and a consequence of the high latent heat of evaporation of water, and this is an important component of the global heat balance of the Earth. The water area of \u200b\u200bthe World Ocean consists of the Atlantic, Pacific, Indian, Arctic and Southern Oceans, marginal seas (Barents, Bering, Okhotsk, Japanese, Caribbean, etc.), inland seas (Mediterranean, Black, Baltic). Having no connection with the World Ocean, the Caspian and Aral seas-lakes are conventionally called seas exclusively because of their large size. At present, these are internal closed bodies of water, and in the Quaternary they were connected to the World Ocean.

The World Ocean contains at least 1.4 billion km3 of water, which is about 94% of the volume of the hydrosphere. These huge masses of water are in constant motion. Geological processes occurring in the World Ocean are diverse and are interrelated phenomena. They consist of the following processes:

Destruction, or abrasion (from the Latin "abrado" - shave, scrape off), rock massifs composing the coast and part of the shallow water;

Transfer and sorting of products of destruction brought from land;

Accumulation, or accumulation, of various precipitation. For a long time, the bottom of the World Ocean and its sediments remained unexplored. Only from the middle of the XX century, purposeful exploration of the World Ocean began with specially built research ships. Initially, various geophysical instruments installed on ships were used to study the bottom of the World Ocean, and rock samples were delivered by special trawls - dredges. As a result of these works, unique information about the topography of the World Ocean bottom was obtained.

Physicochemical properties of the waters of the seas and oceans

Salinity and chemical composition of waters. A large number of substances are dissolved in seawater. The total content of dissolved salts in seawater is called its salinity (5) and is expressed in ppm (% o). The average salinity of ocean waters is taken to be about 35% o. This means that 1 liter of water contains about 35 g of dissolved salts (the average value of the salinity of sea water). The salinity of the surface waters of the World Ocean ranges from 32 to 37% s, and such fluctuations are associated with climatic zoning, which directly affects the evaporation of waters. In arid zones, where evaporation prevails, salinity increases, and in humid areas and in places where large rivers runoff, salinity decreases. Salinity in the inland seas varies over a wide range. In the Mediterranean Sea, it is 35 - 39% o, in the Red Sea it increases to 41 -43% o, and in the seas located in humid regions, salinity decreases mainly due to the large influx of fresh waters. In the Black Sea, it is 18-22% o, in the Caspian -12-15% o, in the Azov -12% o, and in the Baltic - 0.3-6% o. Such low salinity of the Baltic Sea is due to the large volume of river flow. Indeed, such deep rivers as the Rhine, Vistula, Neva, Neman and others carry their waters to this sea. Especially high salinity (up to 300% o) is observed in lagoons separated from the sea in arid regions, for example, in the Kara-Bogaz-Gol Bay in The Caspian Sea.

In the waters of the seas and oceans, almost all chemical elements of the Periodic Table of DI Mendeleev are present. The content of some is so great that it is their ratio that determines the salinity of sea and ocean waters, while the number of others is thousandths and even ten-thousandths of a percent. When comparing cations and anions, it turns out that chlorides (89.1%) predominate in the salt composition of seawater, sulphates are in second place (10.1%), then carbonates are 0.56%, and bromides are only 0.3% ...

Gas mode... In the waters of the World Ocean, various gases are in a dissolved state, but the main ones are oxygen, carbon dioxide and, in some places, hydrogen sulfide. Oxygen enters seawater both directly from the atmosphere and through photosynthesis of phytoplankton. The main role in the redistribution of gases is played by the global ocean circulation. Thanks to it, the flow of oxygen-rich cold waters from high latitudes to the equator and surface waters to the bottom part occurs.

Carbon dioxide is partly in a dissolved state in seawater, and partly it is chemically bound in the form of Ca bicarbonates (HCO3) or carbonates (CaCO3). The solubility of CO2 in seawater depends on the seawater temperature and increases with decreasing temperature. Therefore, the cold waters of the Arctic and Antarctic contain more carbon dioxide than the waters of low latitudes. A significant content of CO2 is noted in the bottom cold waters at depths below 4000 m. This affects the dissolution of carbonate shells of dead organisms, which descend from the surface to the bottom.

In some sea basins, anomalous gas regime is observed. A classic example is the Black Sea, where, according to NM Strakhov, at depths of 150-170 m water is largely depleted in oxygen and contains large amounts of hydrogen sulfide. Its amount increases strongly in the bottom layers. Hydrogen sulfide is formed due to the vital activity of sulfate-containing bacteria, which reduce sulfates from Sea water to hydrogen sulfide. Hydrogen sulfide contamination is caused by disruption of free water exchange between the Black Sea and the Mediterranean Sea. In the Black Sea, water is stratified by salinity. In the upper part there are desalinated waters (17-18% o), and below salty (20-22% o). This excludes vertical circulation and leads to disruption of the gas regime, and then to the accumulation of hydrogen sulfide. Lack of oxygen in deeper layers contributes to the development of recovery processes. Hydrogen sulfide contamination in the bottom part of the Black Sea reaches 5 - 6 cm3 / l. In addition to the Black Sea, hydrogen sulfide contamination has been found in some Norwegian fjords.

Sea water temperature... The temperature distribution of the surface layers of the World Ocean is closely related to climatic zoning. The average annual temperature at high latitudes varies from 0 - 2 ° С and reaches maximum values \u200b\u200bof about 28 ° С in equatorial latitudes. In temperate latitudes, the water temperature experiences significant seasonal fluctuations ranging from 5 to 20 ° C. The water temperature changes with depth, reaching only 2 - 3 ° C in the bottom parts at considerable depths. In the polar regions, it drops to negative values \u200b\u200bof the order of -1.0 -1.8 ° C.

The transition from the upper layer of high temperature water to the lower layer with low temperature occurs in a relatively thin layer called the thermocline. This layer coincides with the 8 - 10 ° isotherm and is located at a depth of 300 - 400 m in the tropics and 500 - 1000 m in the subtropics. The general regularities in the temperature distribution are violated by surface warm and cold currents, as well as by bottom currents.

Pressure and density... Hydrostatic pressure in oceans and seas corresponds to the mass of the water column and increases with depth, reaching a maximum value in the deepest parts of the ocean. The density of seawater averages approximately 1.025 g / cm3. In cold polar waters it increases to 1.028, and in warm tropical waters it decreases to 1.022 g / cm3. All these fluctuations are due to changes in the salinity and temperature of the waters of the World Ocean.

Relief elements.

There are four main stages of the ocean floor relief: continental shelf (shelf), continental slope, ocean floor, and deep-water depressions. Within the ocean floor, the greatest depth differences and grandiose mountain structures are observed. Therefore, within the limits of the bed, they began to distinguish oceanic basins, mid-ocean ridges and oceanic uplifts.

Shelf (continental shelf) - shallow sea terrace, bordering the mainland and being its continuation. Essentially, the shelf is a submerged surface of ancient land. This is an area of \u200b\u200bthe continental crust, which is characterized by a flat relief with traces of flooded river valleys, Quaternary glaciation, and ancient coastlines.

The outer boundary of the shelf is the edge - a sharp bend in the bottom, beyond which the continental slope begins. The average depth of the shelf edge is 133 m, but in specific cases it can vary from several tens to thousands of meters. Therefore, the term "continental shelf" is not suitable for the name of this bottom element (better - the shelf). The shelf width varies from zero (African coast) to thousands of kilometers (Asian coast). In general, the shelf occupies about 7% of the World Ocean area.

Continental slope - the area from the edge of the shelf to the continental foot. The average angle of inclination of the continental slope is about 6 °, but often the steepness of the slope can increase to 20-30 °. Due to the steep fall, the width of the continental slope is usually small - about 100 km. The most characteristic form of the continental slope relief is underwater canyons. Their tops often cut into the edge of the shelf, and their mouth reaches the continental foot.

Continental foot- the third element of the bottom topography, located within the continental crust. The continental foot is a vast sloping plain formed by sedimentary rocks 3-5 km thick. The width of this hilly plain can reach hundreds of kilometers, and the area is close to the areas of the shelf and continental slope.

Ocean bed - the deepest part of the ocean floor, occupying more than 2/3 of the entire area of \u200b\u200bthe World Ocean. The prevailing depths of the ocean floor range from 4 to 6 km, and the bottom topography is the most calm. The main elements are ocean basins, mid-ocean ridges and oceanic uplifts.

Ocean basins - extensive gentle depressions of the ocean floor with depths of about 5 km. The bottom of the basin, flat or slightly hilly, is usually called an abyssal (deep-sea) plain. The leveled surface of the abyssal plains is due to the accumulation of sedimentary material brought from land. The most extensive plains are found in the deep-water areas of the ocean floor. In general, the abyssal plains occupy about 8% of the ocean floor.

Mid ocean ridges - the most tectonically active zones in which a new formation of the earth's crust occurs. They are entirely composed of basaltic rocks formed as a result of their inflow along faults from the bowels of the Earth. This led to the originality of the earth's crust, which composes the mid-oceanic ridges, and its separation into a special riftogenic type.

Oceanic uplifts - large positive landforms of the ocean floor, not associated with mid-oceanic ridges. They are located within the oceanic type of the earth's crust and are distinguished by large horizontal and significant vertical dimensions.

In the deep-water part of the ocean, a large number of detached mountains have been found that do not form any ridges. Their origin is volcanic. Seamounts, the tops of which are a flat platform, are called guyots.

Deep-sea depressions (troughs) - the zone of the greatest depths of the World Ocean, exceeding 6000 m. Their sides are very steep, and the bottom can be leveled if it is covered with sediments. The deepest troughs are located in the Pacific Ocean.

The origin of the troughs is associated with the immersion of the lithospheric plates into the asthenosphere during the new formation of the seabed and the spreading of the plates. The gutters have significant horizontal dimensions. To date, 41 trenches have been discovered in the World Ocean (Pacific Ocean - 25, Atlantic - 7, Indian - 9).

Salinity. Ocean water by weight consists of 96.5% of pure water and 3.5% of dissolved minerals, gases, trace elements, colloids and suspensions of organic and inorganic origin. All known chemical elements are part of the sea water. Most of all in the ocean water sodium, that is, sodium chloride (27.2 g per 1 liter), so the ocean water tastes salty. This is followed by magnesium salts - MgCl (3.8 g per 1 l) and MgSO 4 (1.7 g per 1 l), which give the water a bitter taste. All other elements, including biogenic elements (phosphorus, nitrogen, etc.) and microelements, account for less than 1%, that is, their content is negligible. The total amount of salts in the Ocean reaches 50 10 16 tons. When precipitated, these salts can cover the bottom of the Ocean with a layer of about 60 m, the entire Earth with a layer of 45 m, and land with a layer of 153 m. An amazing feature of ocean water is the constancy of the salt composition. The solution can be in different parts of the Ocean of different concentrations, but the ratio of the main salts remains unchanged.

The average salinity of the World Ocean is 35 ‰. The Atlantic Ocean has the highest average salinity - 35.4 ‰, the lowest - the Arctic Ocean - 32 ‰. Deviations from the average salinity in one direction or the other are mainly caused by changes in the incoming-outgoing balance of fresh water. Atmospheric precipitation falling on the surface of the Ocean, runoff from land, and melting of ice cause a decrease in salinity; evaporation, ice formation - on the contrary, increase it. Since changes in salinity are mainly associated with the inflow and outflow of fresh water, they are noticeable only in the surface layer, which directly receives precipitation and evaporates water, and in a certain layer below it (up to a depth of 1500 m), determined by the mixing depth. Deeper, the salinity of the World Ocean remains unchanged (34.7 - 34.9 ‰).

The salinity of sea water is closely related to its density. Ocean water density– the ratio of the mass of a unit of its volume at a given temperature to the mass of pure water of the same volume at a temperature of + 4 ° C. The density of the Ocean's water always increases with increasing salinity, since the content of substances that have a greater specific gravity than water increases. An increase in the density of surface water layers is facilitated by cooling, evaporation and ice formation. Heating, as well as mixing salt water with precipitation water or melt water, causes a decrease in density. On the ocean surface, a density change is observed in the range from 0.9960 to 1.083. In the open Ocean, density, as a rule, is determined by temperature and therefore generally increases from the equator to the poles. The density of water in the Ocean increases with depth.

Gases in Ocean Water. Gases enter the water from the atmosphere, are released during chemical and biological processes, they are brought by rivers, they come during underwater eruptions. The redistribution of gases occurs through mixing. The ability of ocean water to dissolve gases depends on its temperature, salinity and hydrostatic pressure. The higher the temperature and salinity of the water, the less gases can dissolve in it. Dissolved in water are primarily nitrogen (63%), oxygen (35%) and carbon dioxide, as well as hydrogen sulfide, ammonia, methane, etc.

Carbon dioxide, like oxygen, dissolves better in cold water. Therefore, when the temperature rises, water gives it up to the atmosphere, and when it decreases, it absorbs it. During the day, due to the increased consumption of carbon dioxide by plants, its content in water decreases, at night, on the contrary, increases. At high latitudes, the Ocean absorbs carbon dioxide, at low latitudes, it releases it into the atmosphere. The exchange of gases between the Ocean and the atmosphere is a continuous process.

Pressure.For every square centimeter of the Ocean's surface, the atmosphere presses with approximately 1 kg (one atmosphere). The same pressure on the same area is exerted by a column of water only 10.06 m high. Thus, it can be assumed that for every 10 m depth, the pressure increases by 1 atm. All processes occurring at great depths are carried out under strong pressure, but this does not prevent the development of life in the depths of the Ocean.

Transparency.Radiant energy of the Sun, penetrating into the water column, is scattered and absorbed. The dissipation and absorption of solar energy depends on the amount of suspended particles in the water. The lowest transparency is observed near the shores in shallow water, due to the increase in the amount of suspended matter introduced by the rivers and the roiling of the soil by waves. The transparency of water significantly decreases during the period of mass development of plankton and during ice melting (ice always contains impurities; in addition, the mass of air bubbles trapped in ice passes into water). The transparency of the water increases in places where deep waters rise to the surface.

Transparency is expressed in the number of meters, i.e., the depth at which a white disk with a diameter of 30 cm is still visible.The highest transparency (67 m) was observed in the Central Pacific Ocean, in the Mediterranean Sea - 60 m, in the Indian Ocean - 50 m. In the North sea \u200b\u200bit is 23 m, in the Baltic - 13 m, in the White - 9 m, in the Azov - 3 m.

The color of the water of the oceans and seas. As a result of the collective absorption and scattering of light, the clear water column of the Ocean is blue or blue. The presence of plankton and inorganic suspended matter is reflected in the color of the water, and it acquires a greenish tint. Large amounts of organic impurities make the water yellowish-green; near river mouths it can even be brown.

In equatorial and tropical latitudes, the dominant color of the Ocean's water is dark blue and even blue. Water of this color, for example, in the Bay of Bengal, the Arabian Sea, the southern part of the China Sea, the Red Sea. Blue water in the Mediterranean and Black Seas. In temperate latitudes, in many places, the water is greenish (especially off the coast), it turns green noticeably in areas of melting ice. In polar latitudes, greenish color predominates.

The glow of the sea.The glow of seawater is created by organisms that emit "living" light. These organisms are primarily luminous bacteria. In freshened coastal waters, where such bacteria are prevalent, the glow of the sea is observed in the form of an even milky light. The luminescence is also caused by the smallest and smallest protozoa, of which the night light (Noctiluca) is the most famous. Some larger organisms (large jellyfish, bryozoans, fish, annelids, etc.) also differ in their ability to produce light. Sea glow is a phenomenon common throughout the world's oceans. It is observed only in seawater and never in fresh water.

Blooming sea is the rapid development of zoo and phytoplankton in the surface layers of the sea. Massive accumulations of these organisms cause changes in the color of the sea surface in the form of yellow, pink, milky, green, red, brown and other stripes and spots.

Sound conductivityocean water is 5 times more than air. In air, a sound wave moves at a speed of 332 m / s, in fresh water - 435 m / s, in oceanic water - 1500 m / s. Sound propagation in seawater depends on temperature, salinity, pressure, gas content, as well as suspended organic and inorganic impurities.

World Ocean water temperature... The main source of heat received by the surface of the World Ocean is direct and scattered solar radiation. River waters can serve as an additional source of heat. Part of the incoming solar radiation is reflected by the water surface, part is emitted into the atmosphere and interplanetary space. The sea loses a large amount of heat through evaporation. A large role in the distribution and change in the temperature of the ocean waters belongs to the continents, the prevailing winds and especially currents.

Sea waters touching the atmosphere exchange heat with it. If the water is warmer than the air, then heat is transferred to the atmosphere; if the water is colder, it receives a certain amount of heat in the process of heat exchange.

The heat coming from the Sun is absorbed by a thin surface layer and goes to heating the water, but due to the low thermal conductivity of water, it is almost not transferred to the depth. The penetration of heat from the surface to the underlying layers occurs mainly through vertical mixing, as well as due to the advection of heat by deep currents. As a result of vertical mixing in summer, colder waters rise to the surface and lower the temperature of the surface layers, and deep waters are warmed. In winter, when the surface waters are cooled, warmer waters inflow from the depths in the process of vertical exchange, delaying the onset of ice formation.

The average annual temperature on the surface of the Ocean is + 17.4 ° С, while the average annual air temperature is + 14 ° С. The surface of the Pacific Ocean has the highest average temperature, most of which is located in low latitudes (+ 19.1 ° C), Indian (+ 17.1 ° C), Atlantic (+ 16.9 ° C). Significant temperature changes occur only in the upper layers of the Ocean water with a thickness of 200 - 1000 m. Deeper the temperature does not exceed + 4, + 5 ° С and changes very little. Due to the high heat capacity of water, the Ocean is a solar heat accumulator on Earth.

The process of ice formation in sea and fresh water is different - fresh water freezes at a temperature of 0 ° C (slightly below 0 ° C), and sea water freezes at different temperatures depending on salinity. Ice formation in the Ocean begins with the formation of fresh crystals, which then freeze. At the same time, droplets of strong brine remain in the space between the ice crystals, therefore, the ice is salty when formed. The lower the temperature at which ice formation took place, the saltier the ice. The brine gradually flows between the crystals, so the ice becomes desalinated over time.

In the high latitudes of the northern hemisphere, the ice formed in winter does not have time to melt over the summer; therefore, among the polar ice there are ice of different ages - from one-year to multi-year. The thickness of first-year ice in the Arctic reaches 2 - 2.5 m, in the Antarctic 1 - 1.5 m. Perennial ice has a thickness of 3 - 5 m and more. In the place of ice compression, their thickness reaches 40 m. Ice covers about 15% of the entire water area of \u200b\u200bthe World Ocean, that is, 55 million km 2, including 38 million km 2 in the southern hemisphere.

The ice cover has a huge impact on the climate of the entire Earth, on life in the Ocean.

Ice in the oceans, and especially in the seas, impedes shipping and fishing.

The concept of water masses. The waters of the World Ocean have very different physical and chemical properties. Large volumes of water formed in given physical and geographical conditions at certain intervals of time and differing in characteristic physical, chemical and biological properties are called water masses.

Water masses are formed mainly in the surface layers of the World Ocean under the influence of climatic conditions, processes of thermal and dynamic interaction between the ocean and the atmosphere. In the formation of water masses, the main role belongs to convective mixing, which, like other types of vertical exchange, ends with the formation of a homogeneous water mass. Water masses are transported by currents to other regions, where, in contact with waters of a different origin, they are transformed, especially along the periphery.

Ocean water movement

The entire mass of ocean waters is constantly moving. This ensures constant mixing of water, redistribution of heat, salts and gases. There are 3 types of movement: vibrational - waves, progressive- ocean currents, mixed- ebb and flow.

Waves. The main cause of waves on the surface of the World Ocean is wind. In some cases, the waves reach a height of 18 m and a length of up to 1 km. The waves fade with depth.

With an earthquake, an underwater volcanic eruption and underwater landslides, seismic waves arise that propagate from the epicenter in all directions and cover the entire water column. They're called tsunami. Ordinary tsunamis are waves following one another at intervals of 20-60 minutes at a speed of 400-800 km / h. In the open ocean, the height of a tsunami does not exceed 1 m. When approaching the coast - in shallow water, the tsunami turns into a giant wave up to 15 - 30 m. Such waves cause enormous destruction. Tsunamis more often than others strike the eastern coasts of Eurasia, Japan, New Zealand, Australia, the Philippine and Hawaiian Islands, and the southeastern part of Kamchatka.

Ocean currents. The translational movements of huge masses of water are called currents... It is the horizontal movement of water over long distances. There are currents wind(or drift) when the cause is wind blowing in one direction. Wastewater currents arise in the event of a constant rise in the water level caused by its inflow or heavy precipitation. For example, the Gulf Stream is caused by rising water levels due to influx from the neighboring Caribbean Sea. Compensatorycurrents compensate for the loss of water in any part of the ocean. When the wind constantly blows from land to sea, it drives away surface waters, in place of which cold waters rise from the depths. Densitycurrents are the result of different water densities at the same depth. They can be observed in the straits connecting the seas with different salinity. For example, more salty and denser water flows along the Bosporus Strait along the bottom from the Mediterranean Sea to the Black Sea, and more fresh water flows from the surface towards this stream.

Currents violate latitudinal zoning in temperature distribution. In all three oceans - the Atlantic, Indian and Pacific - under the influence of currents, temperature anomalies arise: positive anomalies are associated with the transfer of warm waters from the equator to higher latitudes by currents having a direction close to the meridional direction; negative anomalies are caused by oppositely directed (from high latitudes to the equator) cold currents. The currents also affect the distribution of other oceanological characteristics: salinity, oxygen content, nutrients, color, transparency, etc. The distribution of these characteristics has a huge impact on the development of biological processes, flora and fauna of the seas and oceans.

Mixed flows - the ebb and flow resulting from the axial rotation of the Earth and the attraction of the planet by the Sun and the Moon. At each point of the Ocean surface, the tide is observed 2 times a day and the ebb tide 2 times. The height of the tidal wave in the open ocean is about 1.5 m, while off the coast it depends on their configuration. The highest tide in the Bay of Fundy off the coast of North America in the Atlantic Ocean is 18 m.

The ocean as a living environment

In the oceans life exists everywhere - in different forms and different manifestations. According to the conditions of existence in the Ocean, two different areas are distinguished: the water column (pelagial) and the bottom (benthal). Benthal is divided into coastal - littoral,having depths of up to 200 m, and deep - abyssal.The abyssal area is represented by peculiar organisms adapted to living in conditions of low temperature, high pressure, lack of light and relatively low oxygen content.

The organic world of the Ocean consists of three groups: benthos, plankton, nekton ... Benthos - inhabitants of the bottom (plants, worms, molluscs), unable to rise for a long time into the water column. Plankton - inhabitants of the water column (bacteria, fungi, algae, protozoa, etc.), which do not have the ability to actively move long distances. Nekton - inhabitants of the waters, freely swimming long distances (whales, dolphins, fish) .

Green plants can only develop where there is sufficient light for photosynthesis (up to a depth of no more than 200 m). Most of the mass of living matter in the Ocean is phytoplankton, which inhabits the upper 100-meter layer of water. The average phytoplankton mass is 1.7 billion tons, the annual production is 550 billion tons. The most common form of phytoplankton is diatoms, represented by 15 thousand species. One diatom algae can produce 10 million specimens per month. Just because phytoplankton dies off quickly and is eaten in large quantities, it has not filled the Ocean. Phytoplankton are the first link in the food chain in the Ocean. Areas of abundant development of phytoplankton are places of increased fertility in the Ocean, rich in life in general.

The distribution of life in the Ocean is very uneven and has a distinct zonal character... In high latitudes of the northern hemisphere, the conditions for the development of phytoplankton are unfavorable - continuous ice cover, polar night, low position of the Sun above the horizon in summer, cold (below 0 ° C) water, weak vertical circulation (a consequence of the desalination of the upper water layer), which does not provide the removal of nutrients from the depths. In summer, some cold-loving fish and fish-eating seals appear in the openings.

IN subpolar latitudesseasonal migration of the polar ice edge occurs. In the cold part of the year, in a layer of several hundred meters, the water is intensively mixed (a consequence of cooling), enriched with oxygen and nutrient salts. In spring and summer, a lot of light comes in, and, despite the relatively low temperature of the water (the result of heat consumption for melting), a lot of phytoplankton develops in it. This is followed by a short period of development of zooplankton feeding on phytoplankton. During this period, a lot of fish (herring, cod, haddock, sea bass, etc.) accumulate in the subpolar zone. Whales, which are especially abundant in the southern hemisphere, come to feed.

IN temperate latitudesboth hemispheres strong mixing of water, a sufficient amount of heat and light create the most favorable conditions for the development of life. These are the most productive areas of the Ocean. The maximum development of phytoplankton is observed in spring. He assimilates nutrients, their amount decreases - the development of zooplankton begins. Autumn is the second maximum of phytoplankton development. The abundance of zooplankton determines the abundance of fish (herring, cod, anchovy, salmon, sardine, tuna, flounder, halibut, navaga, etc.).

IN subtropical and tropicalat latitudes, the water on the surface of the Ocean has increased salinity, but due to the high temperature it turns out to be relatively light, which interferes with mixing. Particles containing nutrients, without lingering, sink to the bottom. Oxygen is 2 times less than in the temperate zone. Phytoplankton develops weakly, and there is little zooplankton. In subtropical latitudes, the water has the greatest transparency and intense blue color (the color of the ocean desert). In warm water, brown algae, which are not associated with the bottom, grow - sargassus, typical for this part of the Ocean.

IN equatorial latitudeswater mixing occurs at the border of trade winds and equatorial countercurrents, and therefore it is relatively rich in nutrient salts and oxygen. There is much more plankton here than in neighboring latitudes, although not as much as on the northern edge of the temperate zone.

Warm water contains little carbon dioxide and therefore poorly dissolves calcium carbonate, which is abundant in it and is easily absorbed by plants and animals. As a result, the shells and skeletons of animals acquire massiveness and strength, and after the withering away of the organisms, powerful strata of carbonate deposits, coral reefs and islands, so characteristic of low latitudes, are formed.

The latitudinal zoning of the distribution of life in the upper layers of the Ocean, well expressed in its open part, is disturbed on the outskirts under the influence of winds and currents.

Salinity. Ocean water by weight consists of 96.5% of pure water and 3.5% of dissolved minerals, gases, trace elements, colloids and suspensions of organic and inorganic origin. All known chemical elements are part of sea water. Most of all in the ocean water sodium, that is, sodium chloride (27.2 g per 1 liter), so the ocean water tastes salty. This is followed by magnesium salts - MgCl (3.8 g per 1 l) and MgSO 4 (1.7 g per 1 l), which give the water a bitter taste. All other elements, including biogenic elements (phosphorus, nitrogen, etc.) and microelements, account for less than 1%, that is, their content is negligible. The total amount of salts in the Ocean reaches 50 10 16 tons. During precipitation, these ...
salts can cover the bottom of the Ocean with a layer of about 60 m, the entire Earth with a layer of 45 m, and the land with a layer of 153 m. An amazing feature of ocean water is the constancy of the salt composition. The solution can be in different parts of the Ocean of different concentrations, but the ratio of the main salts remains unchanged.

The ice cover has a huge impact on the climate of the entire Earth, on life in the Ocean.

Ice in the oceans, and especially in the seas, impedes shipping and fishing.

Ocean water movement

Waves... The main cause of waves on the surface of the World Ocean is wind. In some cases, the waves reach a height of 18 m and a length of up to 1 km. The waves fade with depth.

Ocean currents... The translational movements of huge masses of water are called currents... It is the horizontal movement of water over long distances. There are currents wind (or drift) when the cause is wind blowing in one direction. Wastewater currents arise in the event of a constant rise in the water level caused by its inflow or heavy precipitation. For example, the Gulf Stream is caused by rising water levels due to influx from the neighboring Caribbean Sea. Compensatory currents compensate for the loss of water in any part of the ocean. When the wind constantly blows from land to sea, it drives away surface water, in place of which cold waters rise from the depths. Density currents are the result of different water densities at the same depth. They can be seen in the straits connecting seas with different salinity. For example, more salty and denser water flows along the Bosporus Strait along the bottom from the Mediterranean Sea to the Black Sea, and fresher water flows towards this stream from the surface.

The ocean as a living environment

In the oceans life exists everywhere - in different forms and different manifestations. According to the conditions of existence in the Ocean, two different areas are distinguished: the water column (pelagial) and the bottom (benthal). Benthal is divided into coastal - littoral, having depths of up to 200 m, and deep - abyssal. The abyssal area is represented by peculiar organisms adapted to living in conditions of low temperature, high pressure, lack of light and relatively low oxygen content.

IN subpolar latitudes seasonal migration of the polar ice edge occurs. In the cold part of the year, in a layer of several hundred meters, the water is intensively mixed (as a result of cooling), enriched with oxygen and nutrient salts. In spring and summer, a lot of light comes in, and, despite the relatively low temperature of the water (the result of heat consumption for melting), a lot of phytoplankton develops in it. This is followed by a short period of development of zooplankton feeding on phytoplankton. During this period, a lot of fish (herring, cod, haddock, sea bass, etc.) accumulate in the subpolar zone. Whales, which are especially abundant in the southern hemisphere, come to feed.

IN temperate latitudes both hemispheres strong mixing of water, a sufficient amount of heat and light create the most favorable conditions for the development of life. These are the most productive areas of the Ocean. The maximum development of phytoplankton is observed in spring. He assimilates nutrients, their amount decreases - the development of zooplankton begins. Autumn is the second maximum of phytoplankton development. The abundance of zooplankton determines the abundance of fish (herring, cod, anchovy, salmon, sardine, tuna, flounder, halibut, navaga, etc.).

IN subtropical and tropical At latitudes, the water on the surface of the Ocean has increased salinity, but due to the high temperature it turns out to be relatively light, which interferes with mixing. Particles containing nutrients, without lingering, sink to the bottom. Oxygen is 2 times less than in the temperate zone. Phytoplankton develops weakly, and there is little zooplankton. In subtropical latitudes, the water has the greatest transparency and intense blue color (the color of the ocean desert). In warm water, brown algae, which are not associated with the bottom, grow - sargassus, typical for this part of the Ocean.

IN equatorial latitudes water mixing occurs at the border of trade winds and equatorial countercurrents, and therefore it is relatively rich in nutrient salts and oxygen. There is much more plankton here than in neighboring latitudes, although not as much as on the northern edge of the temperate zone.

The latitudinal zoning of the distribution of life in the upper layers of the Ocean, well expressed in its open part, is disturbed on the outskirts under the influence of winds and currents.

Salinityis the most important feature of ocean water. This solution contains almost all chemical elements known on Earth. The total amount of salts is 50-10 16 tons. They can cover the ocean floor with a layer, they can cover the ocean floor with a layer of 60 m, the entire Earth - 45 m, land - 153 m. The ratio of salts in ocean water remains constant, this is ensured by the high dynamics of ocean waters. The composition is dominated by NaCl (77.8%), MgCl (10.9%), etc.

The average salinity of the ocean water is 35 0/00. The deviation from the average salinity in one direction or another is caused by changes in the incoming and outgoing balance of fresh water. Thus, atmospheric precipitation, water from glaciers, runoff from land reduce salinity; evaporation - increases salinity.

There are both zonal and regional features in the distribution of salinity in the ocean. Zonal features are associated with climatic conditions (distribution of precipitation and evaporation). In the equatorial zone, the waters are slightly saline (O\u003e E), in tropical and subtropical latitudes (E\u003e O), the salinity is maximum for ocean surface waters - 36-37 0/00, to the north and south of this zone salinity decreases. The melting of ice contributes to the decrease in salinity in high latitudes.

Latitudinal zoning in the distribution of salinity on the ocean surface is disturbed by currents. Warm ones increase salinity, cold ones lower it. The average salinity of the oceans on the surface is different. The highest salinity is in the Atlantic Ocean - 35.4 0/00, the least in the Arctic Ocean - 32 0/00 (the desalination role of Siberian waters is great). Salinity changes are mainly associated with surface layers that directly receive fresh water and are determined by the depth of mixing. All changes in salinity occur in the upper layers to a depth of 1500 m, deeper salinity does not change.

World ocean water temperature.

Changes in the course of heat balance elements determine the course of water temperature. The daily amplitudes of water temperature fluctuations on the ocean surface do not exceed, on average, 0.5 0 C. The largest daily amplitude is at low latitudes (up to 1 0 C), the smallest - at high latitudes (up to 0 0 C). Daily fluctuations in ocean temperature play a subordinate role.

Annual amplitudes of temperature fluctuations on the ocean surface are greater than daily ones. Annual temperature fluctuations are small at low (1 0) and high (2 0) latitudes. In the first case, a large amount is evenly distributed throughout the year, in the second - in a short summer, the water does not have time to heat up much. The largest annual amplitudes (from 10 0 to 17 0) are noted in temperate latitudes. The highest average annual water temperatures (27-28 0) are observed in equatorial and tropical latitudes, to the north and south of them the temperature drops to 0 0 C and below in polar latitudes. The thermal equator is located at about 5 ° C N. Ocean currents disturb the zonal temperature distribution. Currents that transfer heat towards the poles (for example, the Gulf Stream) stand out as positive temperature anomalies. Therefore, in tropical latitudes, under the influence of currents, the water temperature at the eastern coasts is higher than at the western ones, and in temperate latitudes, on the contrary, at the western ones it is higher than at the eastern ones. In the southern, more seaward hemisphere, the zoning in the distribution of water temperatures is almost not disturbed. The highest temperature on the ocean surface (+32 0 С) was observed in August in the Pacific Ocean, the lowest in February in the Arctic Ocean (-1.7 0 С). On average, the ocean surface in the southern hemisphere is colder per year than in the northern (the influence of Antarctica). The average annual temperature on the ocean surface is + 17.4 0 С, which is higher than the annual air temperature +14 0. The warmest is the Indian Ocean - about +20 0 C. The heat of solar radiation, heating the upper layer of water, is extremely slowly transferred to the underlying layers. The redistribution of heat in the ocean water column occurs due to convection and mixing by waves and currents. Hence, the temperature decreases with depth. At a depth of about 100-200 m, the temperature drops sharply. The layer of a sharp drop in water temperature with depth is called a thermocline.

Thermocline in the ocean from the equator to 50-60 0 s. and y.sh. exists constantly at depths from 100 to 700 m. In the Arctic Ocean, the water temperature drops to a depth of 50-100 m, and then rises, reaching a maximum at a depth of 200-600 m. than the upper layers of water.

Ice appears in the ocean at high latitudes when the water temperature drops below freezing point. The freezing point depends on its salinity. The higher the salinity, the lower the freezing point. Ice is less dense than fresh ice. Salted ice is less durable than fresh ice, but more plastic and viscous. It does not break on swell (weak excitement). It acquires a greenish tint, in contrast to the blue color of fresh ice. Ice in the ocean can be stationary and floating. Fixed ice is a continuous ice sheet associated with land or shoals. This is usually ice fast ice. Floating ice (drifting) is not connected to the shore and is moved by wind and currents.

1.1 Distribution of water and land on the globe.

The total surface of the land is 510 million square kilometers.

The land area is - 149 million square kilometers. (29%)

Water occupied - 310 million square kilometers. (71%)

In the Northern and Southern Hemispheres, the ratio of the surface of land and water is not the same:

In the Southern Hemisphere, water accounts for 81%

In the Northern Hemisphere, water accounts for 61%

The continents are more or less disconnected from each other, while the ocean waters form a continuous water space on the surface of the globe, which is called the World Ocean. According to the physical and geographical features, the latter is subdivided into separate oceans, seas, bays, bays and straits.

Ocean - the largest part of the World Ocean, bounded from different sides by unconnected continents.

Since the 1930s, the division into 4 oceans has been adopted: Quiet, Indian, Atlantic, Arctic (formerly South Arctic).

The continents dismembering the World Ocean define the natural boundaries between the oceans. In the high southern latitudes there are no such boundaries and they are accepted here conditionally: between the Pacific and Atlantic along the meridian of Cape Horn (6804 ‘W), from Tierra del Fuego Island to Antarctica; between the Atlantic and Indian - from Cape Agulhas along the meridian 20E. ; between Indian and Tikhim - from Cape Yugo - Vostochny on about. Tasmania along the meridian 14655 '.

The areas of the oceans as a percentage of the total area of \u200b\u200bthe World Ocean are;

Quiet - 50%

Atlantic - 25.8%

Indian - 20.8%

North Arctic - 3.6%

In each of their oceans, seas are distinguished and they are more or less isolated and rather extensive areas of the ocean, which have their own hydrological regime, connecting under the influence of local conditions and difficult water exchange with the adjacent areas of the ocean.

The seas are divided into three main groups according to the degree of their isolation from the ocean and physical and geographical conditions:

1. inland seas

a. middle seas

b. semi-closed

2. marginal seas

3. inter-island seas

Mediterranean seas surrounded on all sides by land and communicated with the ocean by one or more straits. They are characterized by the maximum isolation of natural conditions, closed circulation of surface waters and the greatest independence in the distribution of salinity and temperature.

These seas include: Mediterranean, Black, White seas.

Semi-enclosed seas partially bounded by continents and separated from the ocean by peninsulas or a chain of islands, the rapids in the straits between which make it difficult for water exchange, but it is still much freer than in the Mediterranean seas.

Example: the Bering, Okhotsk, Sea of \u200b\u200bJapan, which are separated from the Pacific Ocean by the Aleutian, Kuril, and Japanese islands.

Marginal seas are more or less open parts of the ocean, separated from the ocean by peninsulas or islands.

Water exchange between the seas of this type and the ocean is practically free. The formation of the system of currents and the distribution of salinity and temperature are equally influenced by the continent and the ocean. The marginal seas include: the Arctic seas, except for the White.

Inter-island seas - these are parts of the ocean, surrounded by a ring of islands, the rapids in the straits between which impede some kind of free water exchange. As a result of the influence of the ocean, the natural conditions of these seas are similar to those of the ocean. There is some independence in the nature of the currents and the distribution of temperature and salinity on the surface and at the depth of these seas. Seas of this type include the seas of the East Indian Archipelago: Sulu, Celeba, Benda, Yavan, etc.

The smaller subdivisions of the ocean are bays, bays and straits. The distinction between a bay and a bay is rather arbitrary.

By the bay refers to the part of the sea that juts out into the land and is sufficiently open for the influence of adjacent waters. The largest bays: Biscay, Guinea, Bengal, Alaska, Hudson, Anadyr, etc.

By the bay they call a small bay with the mouth of the bay itself, bounded by islands or peninsulas, which somewhat complicate the water exchange between the bay and the adjacent reservoir. Example Sevastopol, Golden Horn, Tsemeskaya, etc.

In the north, bays deeply protruding into the land where rivers usually flow are called lips, at the bottom of the bay there are traces of river sediments, the water is highly desalinated.

The largest bays: Obskaya, Dvinskaya, Onezhskaya, etc. Winding, low, deeply protruding bays, formed in connection with glacial erosion, are called fjords .

Liman the mouth of a river valley, or gully, flooded by the sea as a result of a slight sinking of the land. Lagoon called: a) a shallow body of water, separated from the sea as a result of sedimentation in the form of a coastal bar and connected to the sea by a narrow strait; b) a section of the sea between the mainland and a coral reef or atoll.

The strait is called a relatively narrow part of the World Ocean, connecting two reservoirs with fairly independent natural conditions.

1.2. Chemical composition and salinity of sea water

Sea water differs from fresh water in taste, specific gravity, transparency, color, and more aggressive impact. Due to the strongly pronounced polarity and large dipole moment of the molecules, water has a great dissociating ability. Therefore, various salts are dissolved in ionic dispersed form, and seawater is essentially a weak, fully ionized solution with an alkaline reaction, which is determined by the excess of the sum of cation equivalents by an average of 2.38 mg-eq / l (alkaline solution). the amount expressed in grams of dissolved in 1 kg of seawater, provided that all halogens are replaced by an equivalent amount of chlorine, all carbonates are converted to oxides, and organic matter is burned, it is customary to call the salinity of seawater. The salinity is indicated by the symbol S. For the unit of salinity, 1 g of salt dissolved in 1000 g of sea water is taken, and is called ppm , denoted by% 0. The average amount of minerals dissolved in 1 kg of seawater is 35g and, therefore, the average salinity of the world ocean is S \u003d 35% 0.

Theoretically, all known chemical elements are found in seawater, but their weight content is different. There are two groups of elements contained in seawater.

1 group. Major ions of ocean water.

Ions and molecules	For 1 kg of water (S \u003d 35% 0)
Ions and molecules
Chloride Cl
Sulphated SO4
Hydrocarbonate HCO3
Bromide B2
Fluoride F
Boric acid H2 BO3
Sum of anions:
Sodium Na
Magnesium Mg
Calcium Ca
Strontium Sr
The amount of cations
The sum of ions

Group 2 - Microelements, the total content of which does not exceed 3 mg / kg.

Individual elements are present in seawater in vanishingly small quantities. Example silver - 310 -7 g, gold - 510 -7 g. The main elements are found in seawater of salt compounds, the main of which are NaCl and MgCl, which constitute 88.7% of the weight of all solids dissolved in seawater ; sulfates MgSO4, CaSO4, K2SO4 constituting 10.8% and CaCO3 carbonate constituting 0.3%. As a result of the analysis of seawater samples, it was found that the content of dissolved minerals can vary over a wide range (from 2 to 30 g / kg), but their percentage with sufficient accuracy for practical purposes can be taken constant. This pattern was named the constancy of the salt composition of sea water .

Based on this regularity, it turned out to be possible to associate the salinity of seawater with the content of chlorine (as an element in the largest amount contained in seawater)

S \u003d 0.030 + 1.805 Cl.

River water contains on average 60.1% carbonates and 5.2% chlorides. However, despite the fact that every year 1.6910 9 tons of carbonates (HCO3) enter the World Ocean with the water of rivers whose runoff is 3.610 4, their total content in the ocean remains practically unchanged. The reasons are:

Intense consumption by maritime organizations to build limestone formations.

Precipitation due to poor solubility.

It should be noted that it is almost impossible to catch changes in the salt content, since the total mass of water in the ocean is 5610 15 tons, and the input of salts is practically negligible. For example, it will take 210 5 years to change the content of chloride ions by 0.02% 0.

Salinity on the surface of the ocean in its open parts depends on the ratio between precipitation and evaporation, and salinity fluctuations for these reasons are 0.2% 0. The greater the difference in temperature between water and air, the wind speed and its duration, the greater the amount of evaporation. This leads to an increase in the salinity of the water. Precipitation decreases surface salinity.

In the polar regions, salinity changes with melting and ice formation and fluctuations here are about 0.7% 0.

Salinity changes across latitudes are approximately the same for all oceans. Salinity increases in the direction from the poles to the tropics, reaching 20-25s. and y. or and decreases again at the equator. Distribution by latitude in the Atlantic Ocean of salinity, precipitation, evaporation, density, water temperature. (Figure 1).

A uniform change in the salinity surface is obtained due to the presence of oceanic and coastal currents, as well as as a result of the outflow of fresh water by large rivers.

The salinity of the seas is the more different from the salinity of the ocean, the less the sea communicates with the ocean.

Salinity of the seas:

Mediterranean 37-38% 0 in the west

38-39% 0 in the east

Red Sea 37% 0 in the south

41% 0 in the north

Persian Gulf 40% 0 in the north

37-38% 0in the east

in depth fluctuations in salinity occur only at a depth of 1500m. Below this horizon, salinity does not change significantly. The distribution of salinity along the depth is influenced by horizontal displacements and vertical circulation of water masses. For a cartographic image of the salinity distribution on the ocean surface or on any other horizon, salinity lines are drawn - isohaline .

1.3. Gases in seawater

Contacting the atmosphere, seawater absorbs gases from the air: oxygen, nitrogen, carbon dioxide.

The amount of dissolved gases in seawater is determined by the partial pressure and solubility of gases, which depends on the chemical nature of the gases and decreases with increasing temperature.

Table of gas solubility in fresh water at a partial pressure of 760 mm Hg.

Solubility of gases (ml / l)
Oxygen	Carbon dioxide	Hydrogen sulfide

The solubility of oxygen and nitrogen, which do not react with sea water, also depends on salinity and decreases with its increase. The content of soluble gases in seawater is estimated in absolute units (ml / l) or as a percentage of the saturated amount, i.e. from the amount of gases that can dissolve in water at a given temperature and salinity, normal humidity and a pressure of 760 mm Hg. Oxygen and nitrogen, due to the better solubility of oxygen in seawater, is in a ratio of 1: 2. The oxygen content fluctuates in time and space from significant supersaturation (up to 350% then in shallow water as a result of photosynthesis, to its complete disappearance when spent on respiration of organisms and oxidation and in the absence of vertical circulation.

Since the solubility of oxygen largely depends on temperature, in the cold season, oxygen is absorbed by sea water, and as the temperature rises, excess oxygen passes into the atmosphere.

Carbon dioxide is contained in the air in an amount of 0.03% and therefore its content in water should have been reached at 0.5 ml / l. However, unlike oxygen and nitrogen, carbon dioxide not only dissolves in water, but also partially enters into compounds with bases (because water is a weakly alkaline reaction). As a result, the total content of free and bound carbon dioxide can reach 50 ml / l. Carbon dioxide is consumed during photosynthesis and for the construction of calcareous formations by organisms. A small part of carbon dioxide (1%) combines with water to form carbonic acid

CO2 + H2O  H2CO3.

Oxygen dissociates releasing bicorbanate and carbonate ions, as well as hydrogen ions

H2CO3  H + HCO3

H2CO3  H + CO3

A normal solution of hydrogen ions contains 1 g
in 1 liter of water. Experiments have established that when the concentration of H ions is 110 -7 g / l, water is neutral. It is pleasant to express the concentration of hydrogen ions with an exponent with the opposite sign and indicate pH.

For neutral water pH \u003d 7

If hydrogen ions prevail pH< 7 (кислая реакция).

If hydroxyl ions predominate, pH\u003e 7 (alkaline reaction).

It was found that with a decrease in the content of free carbon dioxide, pH increases. In the open ocean, water has a slightly alkaline reaction or pH \u003d 7.8 - 8.8.

1.4. Temperature and thermal properties of sea water

Heating of the ocean surface occurs directly and by scattered solar radiation.

In the absence of continents, the temperature on the surface of the ocean would depend only on the latitude of the place. In fact, with the exception of the southern part of the World Ocean, the map is completely different due to the dissection of the ocean, the influence of oceanic plants and vertical circulation.

Average gas temperatures at the surface of the oceans:

Atlantic - 16.9 С

Indian - 17.0 С

Quiet 19.1 С

World - 17.4С

Average air temperature 14.3 С

The highest in the Persian Gulf (35.6 С). The lowest in the Arctic Ocean (-2 С). The temperature decreases with depth to 3000 - 500 m horizons very quickly, further down to 1200 - 1500 m much slower and from 1500 m to the bottom either very slowly or does not change at all. (Fig 2)

Fig. 2. Temperature variation with depth at different latitudes.

Daily temperature fluctuations rapidly decrease with depth and fade out at the 30-50 m horizon. The maximum temperature at a depth occurs 5-6 hours later than at the surface. The depth of penetration of gas temperature fluctuations depends on the weather conditions, but usually does not exceed 300 - 500 m. The specific heat capacity is very high:

1 Cal / g * deg \u003d 4186.8 J / kg * deg.

Substance	Heat capacity Cal / G * deg
Fresh water
Sea water


Liquid ammonia

When 1 cubic cm of water is cooled by 1C, an amount of heat is released, sufficient to heat about 3000 cubic meters by 1 m. cm air.

The thermal conductivity of sea water is determined by the coefficient of molecular thermal conductivity, which varies depending on and on temperature, salinity, pressure in the range (1.3 - 1.4)  10 -3 Cal / cm  degsec.

The transfer of heat in this way is extremely slow. In real conditions, there is always turbulence in fluid motion, and heat transfer in the ocean is always determined by the coefficient of turbulent heat conductivity.

1.5. Density, specific gravity and compressibility of seawater

The density of seawater is the ratio of a unit of weight of a volume of water at a temperature at the time of observation to the weight of a unit of volume of distilled water at a temperature of 4  С ( ).

It is known from physics that density is defined as mass enclosed in units of volume (g / cm ; kg / m ).

Since the density and specific gravity of distilled water at 4 ° C is taken \u003d 1, then numerically the density ( ) and physical density are equal.

In oceanography, density is not measured but calculated through specific gravity, while for intermediate calculations, 2 forms of specific gravity are used:

The following concepts are derived:

Conditional density

Conditional specific gravity at 17.5  FROM

Conditional specific gravity at 0  С (standard conventional weight of sea water)