The World Ocean is a continuous water shell of the Earth, which occupies 71% of its surface (361.1 million km 2). In the Northern Hemisphere, the ocean accounts for 61% of the surface, in the Southern - 81%. The concept of the World Ocean was introduced into Russian science by Yu. M. Shokalsky. According to its physical, chemical, biological features, the World Ocean is a single whole, but it is diverse in many characteristics - climatic, dynamic, optical, elements of the water regime, etc.

Parts of the World Ocean

According to the totality of all signs, the water shell of the Earth is divided into several oceans. These are large parts of the World Ocean, limited by the coastline of the continents. The existence of three oceans is canonically recognized: the Pacific, Atlantic and Indian. In our country and in a number of foreign countries, for example in Great Britain, it is customary to single out the Arctic Ocean. In addition, many recognize the existence of another one - the Southern Ocean, washing the shores of Antarctica. According to more ancient traditions, 7 oceans are also distinguished, dividing the Pacific and Atlantic oceans into the Northern and Southern parts. This is evidenced by the concept of the North Atlantic that has survived to this day.

The division of the World Ocean into separate parts is rather arbitrary. In a number of cases, the borders are also conditional, especially in the south (for example, between the Atlantic and Indian oceans, the Indian and Pacific oceans). Nevertheless, there are a number of signs and characteristics that are inherent in each of the four oceans separately. Each of the oceans has a certain configuration, size, coastline pattern of continents and islands.

Despite the commonality of geostructures (the presence of an underwater margin of the continents, a transition zone, mid-ocean ridges and a bed), they occupy different areas, and the bottom topography of each is individual. The oceans have their own structure of temperature distribution, salinity, water transparency, characteristic features of atmospheric and water circulation, their own system of currents, tides, etc.

The individual features of each ocean make it an independent giant biotope. Physical, chemical and dynamic properties create special conditions for the life of plants and animals.

The oceans greatly influence the formation of natural processes on the continents. Astronauts' visual observations of the oceans confirmed the individuality of each of the oceans, for example, each of them has a specific color. The Atlantic Ocean is seen from space as blue, the Indian Ocean as turquoise, especially off the coast of Asia, and the Arctic Ocean as white.

A number of experts recognize the existence of the fifth ocean - the South Arctic Ocean. It was first identified in 1650 by the Dutch scientist B. Varenius, who proposed the division of the World Ocean into five separate parts - the oceans. The Southern Arctic Ocean is the part of the World Ocean adjacent to Antarctica. In 1845, it was named Antarctic by the Royal Geographical Society of Great Britain, and under these two names, until 1937, it was distinguished by the International Hydrographic Bureau. In domestic literature, it was shown as an independent one in 1966 in the Atlas of the Antarctic. The southern boundary of this ocean is the coastline of Antarctica.

The basis for the identification of the Southern Arctic Ocean is the special very severe climatic and hydrological conditions in this region, increased ice coverage, common circulation of the surface layer of water, etc. Some researchers draw the boundary of the Southern Ocean along the southern periphery of the Antarctic convergence, located on average at 55 ° S. sh. Within the indicated northern boundary, the area of ​​the ocean is 36 million km 2, i.e., it is more than twice the size of the Arctic Ocean.

The climatic and hydrological conditions of the ocean differ in specific features, but are inextricably linked with the adjacent regions of the Pacific, Atlantic and Indian oceans.

The spatial heterogeneity of the oceans is largely determined by their geographic location, structural features of the basin, and morphometric characteristics.

On Earth, more than two-thirds of the surface is covered. The climate of the planet largely depends on the oceans, life originated in it (see the article ""), it provides us with food and many other necessary products. The total volume of the world's oceans is about 1400 million km3, but it is unevenly distributed over the surface of the planet. Most of this water is in the Southern Hemisphere.

There are five major oceans

• The largest of them is, covering 32% of the surface of the globe. It covers an area of ​​more than 160 million km 2 - more than all the land. In addition, it is the deepest ocean; its average depth is 4200 m, and the Mariana Trench has a depth of over 11 km.
• half the size of the Pacific: it covers an area of ​​80 million km 2. It is also inferior to the Pacific Ocean in depth: it reaches its maximum depth (9558 m) in the Puerto Rico trench,
• located in the Southern Hemisphere and covers an area of ​​73.5 million km 2.
• The small one is almost completely surrounded by land and is usually covered with ice 3-4 m thick.
• The Antarctic waters, sometimes referred to as the Antarctic or Southern Ocean, are much larger and surround the mainland. Two-thirds of these waters freeze in winter.

Seas are significantly smaller and shallower parts of the oceans and are partly surrounded by land. These include, for example, the Mediterranean, Baltic, Bering and Caribbean Seas. - a real planet-ocean. From space, the Earth appears blue because the oceans cover 930 million km2. or 71% of its surface.

sea ​​jungle

Coral reefs grow in the warm coastal tropical waters of the world's oceans. The reefs can be called a marine jungle because of the amazing variety of plants and animals found around them.

sperm whales

Sperm whales live in all oceans. This is the most numerous species, but for a long time they were intensively hunted because of fat, which led to a decrease in their numbers. The head of the sperm whale makes up about a third of the entire length of the animal's body. Sperm whales have the largest brains of all mammals.

The first sailors

floating ice

Icebergs are huge ice floes that break away from glaciers or shelf (coastal) ice and float along ocean currents.

oil leak

Man admires the world's oceans, is afraid of it, extracts food from it, but at the same time pollutes and harms it. , such as the one on the Exxon Voldez tanker in March 1989, is just one of many examples of man's devastating impact on the oceans. Fortunately, work is currently underway on .

Mountain ranges at the bottom of the seas

Ridges predominate at the bottom of the seas. The Mid-Atlantic Ridge stretches from north to south, on both sides of it are abyssal (deep) plains. The underwater ridges of the Pacific and Indian Oceans have a more complex shape.

Features of the oceans

The term "World Ocean" was introduced into the practice of scientific research by the French hydrographer Claret de Florier at the end of the 18th century. This concept refers to the totality of the oceans - the Arctic, Atlantic, Pacific and Indian (some researchers also distinguish the Southern Ocean, washing the shores of Antarctica, but its northern borders are rather uncertain), as well as marginal and inland seas. The world ocean occupies 361 million km2, or 70.8% of the earth's area.

The world ocean is not only water, but also aquatic animals and plants, its bottom and shores. At the same time, the World Ocean is understood as an independent integral formation, an object of a planetary scale, as an open dynamic system that exchanges matter and energy with the media that are in contact with it. This exchange takes place in the form of planetary cycles, which involve heat, moisture, salts and gases that are part of the oceans and continents.

Salinity of the oceans

By its structure, sea water is a completely ionized homogeneous solution. Its salinity is determined by the presence in the dissolved state of halides, sulfates, sodium, potassium, magnesium and calcium carbonates (in% 0).

On average, the salinity of the World Ocean is 35% o, but varies within fairly wide limits depending on the level of evaporation and the volume of river runoff. In the case when the river runoff in the seas prevails, the salinity falls below the average value. For example, in the Baltic Sea it is 6-11% o. If evaporation predominates, then salinity rises above the average value. In the Mediterranean Sea, it ranges from 37 to 38% o, and in the Red Sea it is 41% o. The Dead Sea and some saline and bitter-salty lakes (Elton, Baskunchak, etc.) have the highest salinity.

Gases are dissolved in ocean water: N 2, O 2, CO 2, H 2 S, etc. Due to the high horizontal and vertical hydrodynamics, due to the difference in temperature, density and salinity, atmospheric gases are mixed. The change in their content is associated with the vital activity of organisms, underwater volcanism, chemical reactions in the water column and at the bottom, as well as the intensity of the removal of suspended or dissolved matter from the continents.

Some semi-enclosed parts of the World Ocean - the Black Sea or the Gulf of Oman - are characterized by hydrogen sulfide contamination, which spreads from a depth of 200 m. The cause of such contamination is not only juvenile gases, but also chemical reactions that lead to the reduction of sulfates that occur in sediments with the participation of anaerobic bacteria.

Of great importance for the life of marine organisms is the transparency of water, i.e., the depth of penetration of sunlight to the depth. Transparency depends on mineral particles suspended in water and the volume of microplankton. The conditional transparency of ocean water is taken to be the depth at which a white disk, the so-called Secchi disk, with a diameter of 30 cm, becomes invisible. Conditional transparency (m) of parts of the World Ocean is different.

Temperature regime of the oceans

The temperature regime of the ocean is determined by the absorption of solar radiation and the evaporation of water vapor from its surface. The average of the World Ocean is 3.8°С, the maximum, 33°С, is set in the Persian Gulf, and the minimum temperatures are -1.6; -1°C are typical for the polar regions.

At different depths of ocean waters, there is a quasi-homogeneous layer, which is characterized by almost the same temperatures. Below it is the seasonal thermocline. The temperature difference in it during the period of maximum heating reaches 10-15°C. Under the seasonal thermocline lies the main thermocline, covering the main body of ocean waters with a temperature difference of several degrees. The depth of the thermocline in different parts of the same ocean is not the same. It depends not only on the temperature conditions in the near-surface part, but also on the hydrodynamics and salinity of the waters of the World Ocean.

The near-bottom boundary layer adjoins the ocean floor, in which low temperatures are recorded, varying depending on the geographical location from 0.3 to -2 °C.

The density of ocean water changes with temperature. Its average density in the surface areas is 1.02 g/cm 3 . With depth, as temperature decreases and pressure increases, density increases.

Currents of the oceans

As a result of the action of Coriolis forces, temperature differences, fluctuations in atmospheric pressure, interaction with the moving atmosphere, currents arise, which are divided into drift, gradient and tidal. In addition to them, the ocean is characterized by synoptic eddies, seiches and tsunamis.

Drift currents are formed under the action of wind as a result of friction of the air flow on the water surface. The direction of the current makes an angle of 45° with the direction of the wind, which is determined by the influence of the Coriolis forces. A characteristic feature of drift currents is the gradual attenuation of their intensity with a change in depth.

Gradient currents arise as a result of the formation of a slope in the water level under the influence of wind blowing for a long time. The maximum slope is observed near the coast. It creates a pressure gradient, which leads to the appearance of a surge or surge current. Gradient currents capture the entire water column, down to the bottom.

Barogradient and convection currents exist in the World Ocean. Barogradient ones arise as a result of the difference in atmospheric pressure in cyclones and anticyclones over different parts of the World Ocean. Convection currents are formed due to differences in the density of sea water at the same depth, creating a horizontal pressure gradient.

Tidal currents exist in the marginal seas and within marine shallow waters. They arise as a result of the impact on the water column of the gravitational fields of the Earth, the Moon and the Sun, as well as the centrifugal force of the Earth's rotation and the Coriolis forces.

In certain areas of the World Ocean, non-stationary eddy-like perturbations of water up to 400 km in diameter have been discovered. They often cover the entire water column and reach the bottom. Their speed is several centimeters per second. Among them, there are frontal eddies that arise when bends and eddies are cut off from the main flow, and eddies of the open ocean.

Waves caused by earthquakes on the sea or ocean floor. The wavelength ranges from several tens to hundreds of kilometers with a period of 2 to 200 minutes and a speed in the open ocean of up to 1000 km/h. In the open ocean, tsunami waves are about a meter high and may not even be noticed. However, in shallow waters and near the coast, the wave height reaches 40-50 m.

Seiches - standing waves of closed reservoirs, are characteristic only for inland seas. The water in them fluctuates with an amplitude of up to 60 m. The causes of seiches are tidal phenomena or strong winds, leading to surges and surges, as well as sharp changes in atmospheric pressure.

Bioproductivity of the World Ocean

Bioproductivity is determined by the biomass of animals, aquatic plants and microorganisms living in the water column. The total biomass in the World Ocean exceeds 3.9 * 10 9 tons. Of these, about 0.27 * 10 9 tons are found on the shelf, 1.2 * 10 9 tons in coral reef thickets and algae, and 1 in estuaries, 4 * 10 9 tons, and in the open ocean - 1 * 10 9 tons. In the World Ocean there are about 6 million tons of plant matter, mainly in the form of phytoplankton, and about 6 million tons of zooplankton. Shallow waters and underwater sea deltas, located in tropical areas, have the maximum bioproductivity. Significant biological productivity has places where underwater currents come to the surface of the oceans, carrying water enriched with phosphates, nitrates and other salts from depths of more than 200 m. These areas are called upwelling zones. In places where such currents emerge, such as, for example, in the Bay of Benguela, along the coasts of Peru, Chile and Antarctica, zooplankton flourishes.

Ecological functions of the oceans

The World Ocean performs very diverse and extensive ecological functions through the active interaction of the aquatic environment with the atmosphere, lithosphere, continental runoff, and with the organisms inhabiting its expanses.

As a result of interaction with the atmosphere, energy and matter are exchanged, in particular oxygen and carbon dioxide. The most intense oxygen exchange in the ocean system occurs in temperate latitudes.

The oceans provide life to the organisms inhabiting it, giving them warmth and food. Each representative of these very extensive ecosystems (plankton, nekton and benthos) develops depending on the temperature, hydrodynamic regimes and the availability of nutrients. A characteristic example of a direct impact on the life of marine biota is the temperature factor. In many marine organisms, the timing of reproduction is confined to certain temperature conditions. The life of marine animals is directly affected not only by the presence of light, but also by hydrostatic pressure. In ocean waters, it increases by one atmosphere for every 10 m of depth. In the inhabitants of great depths, the variegation of color disappears, they become monotonous, the skeleton is thinned, and from certain depths (deeper than 4500 m), forms with a calcareous shell completely disappear, which are replaced by organisms with a silica or organic skeleton. Surface and deep currents strongly influence the life and distribution of marine biota.

The dynamics of the waters of the World Ocean is one of the constituent parts of the ecological function of the World Ocean. The activity of surface and deep currents is associated with different temperature regimes and with the nature of the distribution of surface and bottom temperatures, the characteristics of salinity, density and hydrostatic pressure. Earthquakes, tsunamis, together with storms and strong wave movements of water, are involved in the widespread marine abrasion of coastal areas. Underwater gravitational processes, as well as underwater volcanic activity, together with underwater hydrodynamics, form the bottom topography of the World Ocean.

The resource role of the World Ocean is great. Sea water itself, regardless of its degree of salinity, is a natural raw material that is used by mankind in various forms. The oceans are a kind of heat accumulator. Slowly heating up, it slowly releases heat and thus is the most important component of the climate-forming system, which, as is known, includes the atmosphere, biosphere, cryosphere and lithosphere.

Part of the kinetic and thermal energy of the World Ocean is fundamentally available for use in human economic activities. Kinematic energy is possessed by waves, ebbs and flows, sea currents, vertical movements of water (upwellings). They constitute energy resources, and, consequently, the World Ocean is an energy base, which is gradually being mastered by mankind. The use of tidal energy has begun and an attempt has been made to use waves and sea surf.

A number of coastal states, located in arid areas and experiencing a shortage of fresh water, place great hopes on the desalination of sea water. Existing desalination plants are energy intensive and therefore they receive electricity at nuclear power plants for their operation. Seawater desalination technologies are quite expensive.

The world's oceans are a global habitat. Marine aquatic organisms live from the surface to the deepest depths. Organisms inhabit not only the water column, but also the seas and oceans. All of them represent biological resources. However, only a small part of the organic world of the ocean is used by mankind. The biological resources of the oceans are only those few groups of marine life, the extraction of which is currently economically justified. These include fish, marine invertebrates (bivalves, cephalopods and gastropods, crustaceans and echinoderms), marine mammals (cetaceans and pinnipeds), and algae.

Many regions of the World Ocean, from the shelf zone to the abyssal depths, have a variety of minerals. The mineral resources of the World Ocean include solid, liquid and gaseous minerals that occur in the coastal strip of land, on the bottom and in the subsoil under the bottom of the World Ocean. They arose in different geodynamic and physiographic conditions. The main of them are coastal placers of titanium-magnetite, zirconium, monazite, cassiterite, native gold, platinum, chromite, silver, diamonds, deposits of phosphorites, sulfur, oil and gas, ferromanganese nodules.

The interaction of the surface of the World Ocean with such a mobile shell as the atmosphere leads to the occurrence of weather phenomena. Cyclones are born over the oceans, which carry moisture to the continents. Depending on the place of their birth, cyclones are divided into cyclones of tropical and extratropical latitudes. The most mobile are tropical cyclones, which often become sources of severe natural disasters covering vast regions. These include typhoons and hurricanes.

The World Ocean, due to its physical and geographical features, the mineral composition of waters and the uniform distribution of temperatures and air moisture, plays a recreational role. Due to the high content of certain ions, sea water, which in its chemical composition is close to the composition of blood plasma, play an important therapeutic role. Due to the balneological and micromineral qualities, the marine areas serve as an excellent place for recreation and treatment of people.

Geological impacts and ecological consequences of natural processes in the World Ocean

Sea waves destroy the coast, carry and deposit detrital material. The abrasion of rocky and loose rocks that make up the coast is associated with drift and tidal currents. Waves continuously undermine and destroy coastal rocks. During storms, colossal masses of water fall on the coast, forming splashes and breakers several tens of meters high. The force of the impact of the waves is such that they are able to destroy and move for some distance bank-protecting structures (breakwaters, breakwaters, concrete blocks) weighing hundreds of tons. The impact force of waves during a storm reaches several tons per square meter. Such waves not only destroy and crush rocks and concrete structures, but also move blocks of rocks weighing tens and hundreds of tons.

Less impressive because of its duration, but a strong impact on the coast is the daily splashing of the waves. As a result of the almost continuous action of waves, a wave-cutting niche is formed at the base of the coastal slope, the deepening of which leads to the collapse of the cornice rocks.

At first, blocks of the destroyed cornice slowly slide towards the sea, and then break up into separate fragments. Large blocks remain at the foot for some time, and the oncoming waves crush and transform them. As a result of prolonged exposure to waves, a platform is formed near the coast, covered with rounded debris - pebbles. A coastal (wave-cutting) ledge, or cliff, appears, and the coast itself recedes inland as a result of erosion. As a result of the action of the waves, wave-cut grottoes, stone bridges or arches and deep clefts are formed.

Massifs of solid rocks detached from the land as a result of erosion, large fragments of sea coasts turn into sea cliffs or columnar rocks. As erosion advances inland, destroying and removing the rocks of the coast, the coastal slope, along which the waves roll, expands and turns into a flat surface called a wave-cut terrace. At low tide, it is exposed, and numerous irregularities are visible on it - pits, ditches, hills, rocky reefs.

Boulders, pebbles and sand, which owe their origin to the action of waves and serve as the cause of wave erosion, eventually erode themselves. They rub against each other, acquiring a rounded shape and decreasing in size.

Depending on the duration and strength of the waves, the rate of erosion and retraction of the coast is different. For example, on the western coast of France (Medoc Peninsula), the coast moves away from the sea at a speed of 15-35 m/year, in the Sochi region - 4 m/year. A striking example of the impact of the sea on land is the island of Helgoland in the North Sea. As a result of wave erosion, its perimeter was reduced from 200 km, which it was in 900, to 5 km in 1900. Thus, its area decreased by 885 km 2 over a thousand years (annual retreat rate was 0.9 km 2 ).

The destruction of the coast occurs when the direction of the waves is perpendicular to the coast. The smaller the angle or the stronger the indentation of the coast, the less marine abrasion, which gives way to the accumulation of clastic material. Pebbles and sand accumulate on capes that limit the entrances to bays and bays, and in places where the action of waves is significantly reduced. Spits begin to form, gradually blocking the entrance to the bay. Then they turn into an embankment that laces the bay from the open sea. There are lagoons. Examples are the Arabat Spit separating the Sivash from the Sea of ​​Azov, the Curonian Spit at the entrance to the Gulf of Riga, etc.

Coastal sediments accumulate not only in the form of spits, but also in the form of beaches, bars, barrier reefs and wave terraces.

The control of coastal erosion and sedimentation in the coastal zone is one of the urgent problems of protecting sea coasts, especially those that are developed by man and are used both as resort areas and as port facilities. In order to prevent sea erosion and damage to port facilities, artificial structures are erected to restrain the activity of waves and coastal currents. Protective walls, lintels, lining, breakwaters, dams, although they limit the impact of storm waves, sometimes they themselves violate the existing hydrological regime. At the same time, in some places the shores suddenly erode, while in others debris begins to accumulate, which sharply reduces navigation. In a number of places, artificial replenishment of beaches with sand is carried out. Special structures constructed in the beach migration zone perpendicular to the shore are successfully used to build up a sandy beach. Knowledge of the hydrological regime made it possible to build wonderful sandy beaches in Gelendzhik and Gagra; at one time, the beach on Cape Pitsunda was saved from erosion. Fragments of rocks for artificially washing the coast were dumped into the sea at certain points, and then the waves themselves were transported along the coast, accumulating and gradually turning into pebbles and sand.

With all its positive impact, the artificial washing of the banks is fraught with negative aspects. Discharged sand and pebbles, as a rule, are mined in the immediate vicinity of the coast, which ultimately adversely affects the ecological state of the region. Mining in the 70s of the XX century. pebbles and sand for construction purposes led to the partial destruction of the Arabat Spit, which led to an increase in the salinity of the Sea of ​​\u200b\u200bAzov and, as a result, caused a reduction and even the disappearance of individual representatives of the marine fauna.

At one time, much attention was paid to the problem of the Kara-Bogaz-Gol Bay. The decrease in the level of the Caspian Sea was directly related to the large volume of evaporation in this bay. It was believed that only the construction of a dam, blocking the access of water to the bay, could save the Caspian Sea. However, the dam not only did not lead to a rise in the level of the Caspian Sea (the sea level began to rise for other reasons and long before the construction of the dam), but also upset the balance between the inflow and evaporation of sea water. This, in turn, caused the drainage of the bay, changed the processes of formation of unique deposits of self-sedimentary salts, led to deflation of the dried salt surface and the spread of salts over great distances. Salt was found even on the surface of the Tien Shan and Pamir glaciers, which caused their increased melting. Due to the wide distribution of salts and excessive irrigation, irrigated lands began to be additionally salinized.

The endogenous geological processes occurring at the bottom of the World Ocean, expressed in the form of underwater eruptions, earthquakes and in the form of "black smokers", are reflected on its surface and adjacent shores in the form of coastal floods and the formation of seamounts and hills. After grandiose underwater collapses, underwater earthquakes and volcanic eruptions in the open ocean, in the epicenter of earthquakes and places of eruptions or underwater collapses, peculiar waves arise - tsunamis. From the place of their origin, tsunamis diverge at a speed of up to 300 m/s. In the open ocean, such a wave, having a large length, can be completely imperceptible. However, as the depth decreases, the height and speed of the tsunami increase when approaching the coast. The height of the waves crashing on the coast reaches 30-45 m, and the speed is almost 1000 km/h. With such parameters, tsunamis destroy coastal structures and lead to large casualties. Especially often the coast of Japan, the western coast of the Pacific and Atlantic oceans are exposed to tsunamis. A typical example of the destructive impact of a tsunami was the famous Lisbon earthquake in 1775. Its epicenter was under the bottom of the Bay of Biscay near the city of Lisbon. At the beginning of the earthquake, the sea receded, but then a huge wave 26 m high hit the shore and flooded the coast to a width of 15 km. Over 300 ships were sunk in Lisbon harbor alone.

The waves of the Lisbon earthquake passed through the entire Atlantic Ocean. At Cadiz, their height reached 20 m, but off the coast of Africa (Tangier and Morocco) - 6 m. Similar waves reached the shores of America after some time.

As you know, the sea is constantly changing its level, and this is especially noticeable on the coastal ledges. There are short-period (minutes, hours and days) and long-period (from tens of thousands to millions of years) fluctuations in the level of the World Ocean.

Short-term fluctuations in sea level are mainly due to the dynamics of waves - wave movements, gradient, drift and tidal movements. Surge floods are the most negative from an ecological point of view. The most famous among them are surge floods in St. Petersburg, which occur during strong westerly winds in the Gulf of Finland, which delay the flow of water from the Neva into the sea. The rise of water above the ordinary (above the zero mark on the water gauge, showing the average long-term water level) occurs quite often. One of the most significant rises in water occurred in November 1824. At this time, the water level rose 410 cm above the ordinary.

In order to stop the negative impact of surge flooding, the construction of a protective dam was begun, blocking the Neva Bay. However, long before the completion of construction, its negative aspects were revealed, which led to changes in the hydrological regime and the accumulation of pollutants in silt sediments.

Long-term changes in sea level are associated with changes in the total amount of water in the World Ocean and are manifested in all its parts. Their causes are the emergence and subsequent melting of sheet glaciers, as well as changes in the volume of the World Ocean bowl as a result of tectonic movements. Different-scale and different-age changes in the level of the World Ocean have been established as a result of paleogeographic reconstructions. On the geological material, global transgressions (advance) and regressions (retreat) of the seas and oceans are revealed. Their ecological consequences were negative, as the living conditions of organisms changed and food resources were reduced.

During the cooling period at the beginning of the Quaternary, a huge amount of sea water was withdrawn from the Arctic Ocean. At the same time, the shelves of the northern seas that protruded onto the earth's surface were covered with an ice shell. After the Holocene warming and the melting of the ice sheet, the shelves of the northern seas were again filled, and the White and Baltic Seas appeared in the depressions of the relief.

Large environmental consequences as a result of sea level fluctuations are noticeable on the coasts of the Black, Azov and Caspian Seas. Buildings of the Greek colony of Dioscuria were flooded in the Sukhumi Bay, Greek amphoras were found at the bottom off the coast of the Taman Peninsula in Crimea, and flooded Scythian burial mounds were found off the northern coast of the Sea of ​​Azov. Signs of coastal subsidence are pronounced on the western coast of the Black Sea. Here, under the water, Roman buildings were found, built about 3 thousand years BC. e., as well as sites of early Neolithic man. All of these subsidences are associated with a post-glacial rise in sea levels as a result of the vigorous melting of ice sheets.

The rises and falls of the sea level have been especially well recorded in the study of the terraces of the Mediterranean.

The relative rise in the water level leads to flooding of coastal areas. This is due to backwater and rising groundwater. Flooding causes the destruction of foundations and flooding of basements in cities, and in rural areas leads to waterlogging, salinization and waterlogging of soils. It is this process that is currently taking place on the coast of the Caspian Sea, the level of which is rising. In some cases, transgressions in limited areas are caused by human economic activity. One of the reasons for the flooding of the city of Venice in the 70-80s of the XX century. The waters of the Adriatic Sea are considered to be the subsidence of the seabed caused by subsidence due to the pumping of fresh groundwater.

Global and Regional Ecological Consequences in the World Ocean as a Result of Anthropogenic Activities

Active human economic activity has also affected the oceans. Firstly, mankind began to use the waters of the internal and marginal seas and ocean spaces as transport routes, secondly, as a source of food and mineral resources, and thirdly, as a repository of solid and liquid chemical and radioactive waste. All of the above actions have given rise to many environmental problems, some of which have proved intractable. In addition, the World Ocean, as a global natural complex with a more closed system than land, has become a kind of sump for various suspensions and dissolved compounds carried from the continents. The effluents and substances produced on the continents as a result of economic activity are brought by surface waters and winds into inland seas and oceans.

According to international practice, the part of the World Ocean adjacent to land is divided into territories with different state jurisdiction. From the outer boundary of internal waters, a zone of territorial waters with a length of 12 miles is distinguished. A 12-mile contiguous zone extends from it, which, together with territorial waters, has a width of 24 miles. A 200-mile economic zone stretches from inland waters towards the open sea, which is the territory of the sovereign right of the coastal state to explore, develop, preserve and reproduce biological and mineral resources. The state has the right to lease its economic zone.

Currently, there is an intensive development of the economic zone of the oceans. Its area is about 35% of the area of ​​the entire oceans. It is this territory that experiences the maximum anthropogenic load from the coastal states.

A striking example of ongoing pollution is the Mediterranean Sea, which washes the land of 15 states with different levels of industrial development. It has become a huge repository of industrial and domestic waste and sewage. Taking into account the fact that the water in the Mediterranean Sea is renewed every 50-80 years, at the current rate of wastewater discharge, its existence as a relatively clean and safe basin may completely cease in 30-40 years.

A large source of pollution are rivers, which, together with suspended particles formed from the erosion of land rocks, contribute a large amount of pollutants. Only the Rhine in the territorial waters of Holland takes out annually 35 thousand m 3 of solid waste, 10 thousand tons of chemicals (salts, phosphates and toxic substances).

In the World Ocean, a gigantic process of bioextraction, bioaccumulation and biosedimentation of pollutants is taking place. Its hydrological and biogenic systems are continuously working and due to this, the biological purification of the waters of the World Ocean is carried out. The marine ecosystem is dynamic and fairly resistant to moderate anthropogenic impact. Its ability to return to its initial state (homeostasis) after a stressful situation is the result of many adaptive processes, including mutational ones. Due to homeostasis, the processes of destruction of ecosystems at the first stage go unnoticed. However, homeostasis is not able to prevent long-term evolutionary changes or withstand powerful anthropogenic impact. Only long-term observations of physical, geochemical and hydrobiological processes make it possible to assess in which direction and at what speed the destruction of marine ecosystems occurs.

Recreational zones also play a certain role in the pollution of territorial waters, which include both natural and artificially created territories traditionally used for recreation, treatment and entertainment. The high anthropogenic load of these territories significantly changes the purity of water and worsens the bacterial situation of coastal waters, which contributes to the spread of various diseases, including epidemic ones.

Oil and oil products pose the greatest danger to hydrobionts. Every year, over 6 million tons of oil enter the World Ocean through various routes. Over time, oil penetrates into the water column, accumulates in bottom sediments and affects all groups of organisms. More than 75% of oil pollution occurs due to the imperfection of oil production, transportation and processing. However, accidental oil spills cause the greatest harm. Of particular danger are accidents at fixed and floating drilling rigs developing offshore oil and gas fields, as well as accidents on tankers carrying oil products. One ton of oil is capable of covering a water area of ​​12 km 2 with a thin layer. The oil film does not let the sun's rays through and prevents photosynthesis. Animals caught in a film of oil are not able to get rid of it. Especially often the fauna in coastal waters perishes.

Oil pollution has a pronounced regional character. The lowest concentration of oil pollution is observed in the Pacific Ocean (0.2-0.9 mg/l). The Indian Ocean has the highest level of pollution: in some areas, the concentration reaches 300 mg / l. The average concentration of oil pollution in the Atlantic is 4-5 mg/l. Shallow marginal and inland seas - the North Sea, the Sea of ​​Japan, and others - are especially heavily polluted with oil.

Oil pollution is characterized by eutrophication of the water area and, as a result, a decrease in species diversity, the destruction of trophic relationships, the mass development of a few species, structural and functional rearrangements of the biocenosis. After an oil spill, the number of hydrocarbon-oxidizing bacteria increases by 3-5 orders of magnitude.

Over the past quarter century, about 3.5 million tons of DDT have entered the World Ocean. Having a high solubility in fats, this drug and its metabolic products are able to accumulate in the tissues of organisms and retain their toxic effect for many years.

Until 1984, radioactive waste was buried in the World Ocean. In our country, it was carried out most intensively within the Barents and Kara seas, as well as in some places of the Far Eastern seas. At present, according to international agreements, the practice of disposal of radioactive waste is suspended due to the fact that the safety of used containers in which radioactive waste is stored is limited to several decades.

However, the risk of radioactive contamination of the oceans remains in connection with ongoing accidents of nuclear submarines, emergencies on nuclear icebreakers, accidents of surface ships carrying nuclear weapons, accidents and losses of nuclear warheads on aircraft, as well as nuclear explosions carried out by France on Mororua Atoll.

The most dangerous of the radioactive isotopes for marine biocenoses and humans entering the World Ocean are 90 Sr and 137 Cs involved in the biological cycle.

Pollutants also enter the World Ocean from air currents or with precipitation in the form of acid rain.

The spread of pollution of the World Ocean is facilitated not only by the interaction of its surface with the atmosphere, but also by the very dynamics of waters. Due to their mobility, waters spread pollutants relatively quickly throughout the oceans.

Pollution of the oceans is a global threat. Anthropogenic impacts change all existing interconnected systems of the World Ocean, cause damage to flora and fauna, including humans. Its pollution not only contributes to the spread of toxic substances, but also significantly affects the global distribution of oxygen. After all, one-fourth of all oxygen production by plants occurs in the oceans.

Our Earth looks like a blue planet from space. This is because ¾ of the surface of the globe is occupied by the World Ocean. It is one, though very divided.

The surface area of ​​the entire World Ocean is 361 million square meters. km.

Oceans of our planet

The ocean is the water shell of the earth, the most important component of the hydrosphere. Continents divide the oceans into parts.

Currently, it is customary to distinguish five oceans:

. - the largest and oldest on our planet. Its surface area is 178.6 million square meters. km. It occupies 1/3 of the Earth and makes up almost half of the oceans. To imagine this value, it is enough to say that all the continents and islands together can easily be placed in the Pacific Ocean. This is probably why it is often called the Great Ocean.

The Pacific Ocean owes its name to F. Magellan, who, during his round-the-world trip, crossed the ocean under favorable conditions.

The ocean has an oval shape, its widest part is located near the equator.

The southern part of the ocean is an area of ​​calm, light winds and a stable atmosphere. To the west of the Tuamotu Islands, the picture changes dramatically - here is an area of ​​​​storms and heavy winds, turning into ferocious hurricanes.

In the tropics, the waters of the Pacific Ocean are clear, transparent and have a deep blue color. A favorable climate formed near the equator. The air temperature here is +25ºC and practically does not change throughout the year. Winds of moderate strength, often calm.

The northern part of the ocean is similar to the southern, as if in a mirror image: in the west, unstable weather with frequent storms and typhoons, in the east - peace and quiet.

The Pacific Ocean is the richest in terms of the number of animal and plant species. Over 100 thousand species of animals live in its waters. Almost half of the world's fish catch is caught here. The most important sea routes are laid across this ocean, connecting 4 continents at once.

. covers an area of ​​92 million square meters. km. This ocean, like a huge strait, connects the two poles of our planet. The Mid-Atlantic Ridge runs through the center of the ocean, famous for the instability of the earth's crust. Separate peaks of this ridge rise above the water and form islands, the largest of which is Iceland.

The southern part of the ocean is under the influence of the trade winds. There are no cyclones here, so the water here is calm, clean and transparent. Closer to the equator, the Atlantic changes completely. The waters here are muddy, especially along the coast. This is due to the fact that large rivers flow into the ocean in this part.

The northern tropical zone of the Atlantic is famous for its hurricanes. Two major currents meet here - the warm Gulf Stream and the cold Labrador.

The northern latitudes of the Atlantic are the most picturesque area with huge icebergs and powerful ice tongues protruding from the waters. This area of ​​the ocean is dangerous for navigation.

. (76 million sq. km) - the area of ​​​​the most ancient civilizations. Navigation here began to develop much earlier than in other oceans. The average depth of the ocean is 3700 meters. The coastline is slightly indented, with the exception of the northern part, where most of the seas and bays are located.

The waters of the Indian Ocean are more salty than in others, as far fewer rivers flow into it. But, thanks to this, they are famous for their amazing transparency and rich azure and blue color.

The northern part of the ocean is a monsoon region, and typhoons often form in autumn and spring. Further south, the water temperature is lower due to the influence of Antarctica.

. (15 million sq. km) is located in the Arctic and occupies vast areas around the north pole. The maximum depth is 5527m.

The central part of the bottom is a continuous intersection of mountain ranges, between which there is a huge basin. The coastline is heavily indented by seas and bays, and in terms of the number of islands and archipelagos, the Arctic takes second place after such a giant as the Pacific Ocean.

The most characteristic part of this ocean is the presence of ice. The Arctic Ocean remains by far the least explored, as research is hampered by the fact that most of the ocean is hidden under the ice cover.

. . The waters surrounding Antarctica combine signs. Allowing them to be separated into a separate ocean. But there are still disputes about what to consider borders. If from the south the borders are marked by the mainland, then the northern borders are most often drawn along 40-50º south latitude. Within such limits, the ocean area is 86 million square meters. km.

The bottom relief is cut by underwater canyons, ridges and basins. The fauna of the Southern Ocean is rich, there is the largest number of endemic animals and plants.

Characteristics of the oceans

The oceans are several billion years old. Its prototype is the ancient Panthalassa ocean, which existed when all the continents were still a single whole. Until recently, the bottom of the oceans was assumed to be flat. But it turned out that the bottom, like the land, has a complex relief, with its mountains and plains.

Properties of the waters of the oceans

The Russian scientist A. Voyekov called the World Ocean "a huge heating battery" of our planet. The fact is that the average water temperature in the oceans is +17ºC, and the average air temperature is +14ºC. Water heats up much longer, but it also consumes heat more slowly than air, while having high heat capacity.

But not all the water column in the oceans has the same temperature. Under the sun, only surface waters heat up, and with depth, the temperature drops. It is known that at the bottom of the oceans the average temperature is only +3ºC. And it remains so because of the high density of water.

It should be remembered that the water in the oceans is salty, and therefore it freezes not at 0ºC, but at -2ºC.

The degree of salinity of the waters varies depending on the geographic latitude: in temperate latitudes, the waters are less saline than, for example, in the tropics. In the north, the waters are also less saline due to the melting of glaciers, which greatly desalinate the water.

The waters of the ocean are also different in terms of transparency. At the equator, the water is clearer. As the distance from the equator increases, the water becomes saturated with oxygen faster, which means that more microorganisms appear. But near the poles, due to low temperatures, the waters become more transparent again. So, the waters of the Weddell Sea near Antarctica are considered the most transparent. The second place belongs to the waters of the Sargasso Sea.

The difference between the ocean and the sea

The main difference between the sea and the ocean is in size. The oceans are much larger, and the seas are often only part of the oceans. The seas also differ from the ocean, to which they belong, by their unique hydrological regime (water temperature, salinity, transparency, distinctive composition of flora and fauna).

The climate of the oceans

Climate of the Pacific infinitely diverse, as the ocean is located in almost all climatic zones: from equatorial to subarctic in the north and Antarctic in the south. There are 5 warm currents and 4 cold currents in the Pacific Ocean.

The greatest amount of precipitation falls in the equatorial zone. The amount of precipitation exceeds the proportion of water evaporation, so the water in the Pacific Ocean is less salty than in others.

climate of the atlantic ocean determined by its large extent from north to south. The equator zone is the narrowest part of the ocean, so the water temperature here is lower than in the Pacific or Indian.

The Atlantic is conditionally divided into northern and southern, drawing the border along the equator, and the southern part is much colder due to its proximity to Antarctica. Many areas of this ocean are characterized by thick fogs and powerful cyclones. They are strongest near the southern tip of North America and in the Caribbean.

On formation Indian Ocean climate the proximity of two continents - Eurasia and Antarctica - has a huge impact. Eurasia actively participates in the annual change of seasons, bringing dry air in winter and filling the atmosphere with excess moisture in summer.

The proximity of Antarctica causes a decrease in water temperature in the southern part of the ocean. Hurricanes and storms are frequent north and south of the equator.

Formation climate of the Arctic Ocean determined by its geographic location. Arctic air masses dominate here. Average air temperature: from -20 ºC to -40 ºC, even in summer the temperature rarely rises above 0ºC. But the waters of the ocean are warmer due to constant contact with the Pacific and Atlantic oceans. Therefore, the Arctic Ocean warms a significant part of the land.

Strong winds are rare, but fogs are frequent in summer. Precipitation falls mainly in the form of snow.

It is influenced by the proximity of Antarctica, the presence of ice and the absence of warm currents. The Antarctic climate dominates here with low temperatures, cloudy weather and mild winds. Snow falls throughout the year. A distinctive feature of the climate of the Southern Ocean is the high activity of cyclones.

The influence of the ocean on the Earth's climate

The ocean has a tremendous influence on the formation of climate. It accumulates huge reserves of heat. Thanks to the oceans, the climate on our planet is becoming milder and warmer, since the temperature of the waters in the oceans does not change as sharply and quickly as the temperature of the air over land.

Oceans contribute to better circulation of air masses. And such an important natural phenomenon as the water cycle provides the land with a sufficient amount of moisture.

It is believed that the first person to visit the Pacific Ocean on a ship was Magellan. In 1520, he circled South America and saw new expanses of water. Since Magellan's team did not meet a single storm during the entire journey, the new ocean was called " Quiet".

But even earlier in 1513 the Spaniard Vasco Nunez de Balboa headed south from Colombia to what he was told was a wealthy country with a large sea. Having reached the ocean, the conquistador saw an endless expanse of water stretching to the west, and called it " South Sea".

Fauna of the Pacific Ocean

The ocean is famous for its rich flora and fauna. About 100 thousand species of animals live in it. There is no such diversity in any other ocean. For example, the second largest ocean - Atlantic, is inhabited by "only" 30 thousand species of animals.

There are several places in the Pacific Ocean where the depth exceeds 10 km. These are the famous Mariana Trench, the Philippine Trench and the Kermadec and Tonga depressions. Scientists were able to describe 20 species of animals that live at such a great depth.

Half of all seafood consumed by humans is caught in the Pacific Ocean. Among 3,000 fish species, industrial-scale fishing is open for herring, anchovies, mackerels, sardines, etc.

Climate

The large extent of the ocean from north to south quite logically explains the diversity of climatic zones - from equatorial to Antarctic. The largest zone is the equatorial zone. Throughout the year, the temperature here does not fall below 20 degrees. Temperature fluctuations during the year are so small that we can safely say that it is always +25 there. There is a lot of precipitation, more than 3,000 mm. in year. Very frequent cyclones are characteristic.

The amount of precipitation is greater than the amount of evaporating water. Rivers, which bring more than 30,000 m³ of fresh water into the ocean every year, make surface water less saline than other oceans.

The relief of the bottom and islands of the Pacific Ocean

The bottom relief is extremely varied. Located in the east East Pacific Rise where the terrain is relatively flat. In the center are basins and deep-sea trenches. The average depth is 4,000 m, and in some places exceeds 7 km. The bottom of the center of the ocean covers the products of volcanic activity with a high content of copper, nickel and cobalt. The thickness of such deposits in some areas can be 3 km. The age of these rocks begins with the Jurassic and Cretaceous period.

At the bottom there are several long chains of seamounts formed as a result of the action of volcanoes: mountains of the Emperor, Louisville and the Hawaiian islands. There are about 25,000 islands in the Pacific Ocean. That's more than all the other oceans combined. Most of them are located south of the equator.

Islands are classified into 4 types:

1. continental islands. Very closely related to the continents. Includes New Guinea, the islands of New Zealand and the Philippines;
2. high islands. Appeared as a result of eruptions of underwater volcanoes. Many of today's high islands have active volcanoes. For example, Bougainville, Hawaii and the Solomon Islands;
3. Coral raised atolls;

The last two types of islands are huge colonies of coral polyps that form coral reefs and islands.

• This ocean is so huge that its maximum width is equal to half the earth's equator, i.e. more than 17 thousand km.
• The animal world is large and varied. Even now, new animals unknown to science are regularly discovered there. So, in 2005, a group of scientists discovered about 1000 species of decapod cancer, two and a half thousand mollusks and more than a hundred crustaceans.
• The deepest point on the planet is in the Pacific Ocean in the Mariana Trench. Its depth exceeds 11 km.
• The highest mountain in the world is located in the Hawaiian Islands. It is called Muana Kea and is an extinct volcano. The height from the base to the top is about 10,000 m.
• At the bottom of the ocean is Pacific volcanic ring of fire, which is a chain of volcanoeslocated along the perimeter of the entire ocean.

The largest oceans are the Pacific, Atlantic and Indian. The Pacific Ocean (area 178,684,000 km²) is round in plan and occupies almost half of the water surface of the globe. The Atlantic Ocean (91,660,000 km²) is shaped like a wide S, with its western and eastern coasts nearly parallel. The Indian Ocean, with an area of ​​76,174,000 km², has the shape of a triangle.

The Arctic Ocean with an area of ​​​​only 14,750,000 km² is surrounded by land on almost all sides. Like Quiet, it has a rounded shape. Some geographers identify another ocean - the Antarctic, or the South - a body of water surrounding Antarctica with an area of ​​20,327,000 km².

ocean and atmosphere

The oceans, the average depth of which is approx. 4 km, contains 1350 million km3 of water. The atmosphere, enveloping the entire Earth in a layer several hundred kilometers thick, with a much larger base than the World Ocean, can be considered as a "shell". Both the ocean and the atmosphere are the fluids in which life exists; their properties determine the habitat of organisms. Circulation flows in the atmosphere affect the general circulation of water in the oceans, and the properties of ocean waters largely depend on the composition and temperature of the air. In turn, the ocean determines the main properties of the atmosphere and is a source of energy for many processes occurring in the atmosphere. The circulation of water in the ocean is affected by winds, the rotation of the Earth, and land barriers.

Ocean and climate

It is well known that the temperature regime and other climatic characteristics of the area at any latitude can change significantly in the direction from the ocean coast to the interior of the mainland. Compared to land, the ocean heats up more slowly in summer and cools more slowly in winter, smoothing out temperature fluctuations on adjacent land.

The atmosphere receives from the ocean a significant part of the heat coming to it and almost all of the water vapor. The vapor rises, condenses, and forms clouds that are carried by the winds and support life on the planet, falling as rain or snow. However, only surface waters participate in heat and moisture exchange; more than 95% of the water is in the depths, where its temperature remains virtually unchanged.

Composition of sea water

The ocean water is salty. The salty taste comes from the 3.5% dissolved minerals it contains—mainly sodium and chlorine compounds—the main ingredients in table salt. Magnesium is next in number, followed by sulfur; all common metals are also present. Of the non-metallic components, calcium and silicon are especially important, since they are involved in the structure of the skeletons and shells of many marine animals. Due to the fact that the water in the ocean is constantly mixed by waves and currents, its composition is almost the same in all oceans.

sea ​​water properties

The density of sea water (at a temperature of 20 ° C and a salinity of approx. 3.5%) is approximately 1.03, i.e. slightly higher than the density of fresh water (1.0). The density of water in the ocean varies with depth due to the pressure of the overlying layers, as well as depending on temperature and salinity. In the deepest parts of the ocean, the waters tend to be saltier and colder. The densest masses of water in the ocean can remain at depth and maintain a lower temperature for more than 1000 years.

Since sea water has a low viscosity and high surface tension, it offers relatively little resistance to the movement of a ship or swimmer and flows quickly from various surfaces. The predominant blue color of sea water is associated with the scattering of sunlight by small particles suspended in water.

Sea water is much less transparent to visible light than air, but more transparent than most other substances. Recorded penetration of sunlight into the ocean to a depth of 700 m. Radio waves penetrate into the water column only to a shallow depth, but sound waves can propagate under water for thousands of kilometers. The speed of sound propagation in sea water fluctuates, averaging 1500 m per second.

The electrical conductivity of sea water is about 4000 times higher than that of fresh water. The high salt content prevents its use for irrigation and irrigation of agricultural crops. It is also unsuitable for drinking.

inhabitants

Life in the ocean is extremely diverse - more than 200,000 species of organisms live there. Some of them, such as the lobe-finned coelacanth fish, are living fossils whose ancestors flourished here more than 300 million years ago; others have appeared more recently. Most marine organisms are found in shallow waters where sunlight penetrates to promote photosynthesis. Zones enriched with oxygen and nutrients, such as nitrates, are favorable for life. Widely known is the phenomenon of "upwelling" (English upwelling), - the rise to the surface of deep sea waters enriched with nutrients; it is with him that the richness of organic life is associated along some coasts. Life in the ocean is represented by a wide variety of organisms - from microscopic single-celled algae and tiny animals to whales exceeding 30 m in length and larger than any animal that has ever lived on land, including the largest dinosaurs. Oceanic biota is divided into the following main groups.

Plankton

Plankton is a mass of microscopic plants and animals that are not capable of independent movement and live in the near-surface well-lit layers of water, where they form floating "feeding grounds" for larger animals. Plankton consists of phytoplankton (including plants such as diatoms) and zooplankton (jellyfish, krill, crab larvae, etc.).

Nekton

Nekton consists of free-floating organisms in the water column, mostly predatory, and includes more than 20,000 species of fish, as well as squid, seals, sea lions, and whales.

Benthos

Benthos consists of animals and plants that live on or near the ocean floor, both at great depths and in shallow water. Plants represented by various algae (for example, brown ones) are found in shallow water, where sunlight penetrates. Of the animals, sponges, sea lilies (at one time considered extinct), brachiopods, and others should be noted.

food chains

More than 90% of the organic substances that make up the basis of life in the sea are synthesized under sunlight from minerals and other components by phytoplankton, which abundantly inhabit the upper layers of the water column in the ocean. Some organisms that make up zooplankton eat these plants and in turn are a food source for larger animals that live at greater depths. Those are eaten by larger animals that live even deeper, and this pattern can be traced to the very bottom of the ocean, where the largest invertebrates, such as glass sponges, receive the nutrients they need from the remains of dead organisms - organic detritus that sinks to the bottom from the overlying water column. However, it is known that many fish and other free-roaming animals have managed to adapt to the extreme conditions of high pressure, low temperature and constant darkness that are characteristic of great depths.

Waves, tides, currents

Like the entire universe, the ocean is never at rest. A variety of natural processes, including such catastrophic ones as underwater earthquakes or volcanic eruptions, cause the movement of ocean waters.

Waves

Ordinary waves are caused by wind blowing at varying speeds over the surface of the ocean. First, ripples appear, then the surface of the water begins to rise and fall rhythmically. Although the water surface rises and falls, individual water particles move along a trajectory that is almost a vicious circle, with little or no horizontal displacement. As the wind gets stronger, the waves get higher. In the open sea, the height of the crest of a wave can reach 30 m, and the distance between adjacent crests is 300 m.

Approaching the shore, the waves form breakers of two types - diving and sliding. Diving breakers are characteristic of waves that originated at a distance from the coast; they have a concave front, their crest overhangs and collapses like a waterfall. Sliding breakers do not form a concave front, and the wave declines gradually. In both cases, the wave rolls onto the shore and then rolls back.

catastrophic waves

Catastrophic waves can occur as a result of a sharp change in the depth of the seabed during the formation of faults (tsunamis), during severe storms and hurricanes (storm surges), or during avalanches and landslides of cliffs.

Tsunamis can propagate in the open ocean at speeds up to 700–800 km/h. When approaching the shore, the tsunami wave slows down, and its height simultaneously increases. As a result, a wave with a height of up to 30 m or more (relative to the mean ocean level) rolls onto the coast. Tsunamis have tremendous destructive power. Although areas near seismically active zones such as Alaska, Japan, Chile suffer the most from them, waves from distant sources can cause significant damage. Similar waves occur during explosive volcanic eruptions or the collapse of crater walls, as, for example, during the volcanic eruption on the island of Krakatau in Indonesia in 1883.

Even more destructive can be storm waves generated by hurricanes (tropical cyclones). Repeatedly similar waves crashed on the coast in the upper part of the Bay of Bengal; one of them in 1737 led to the death of about 300 thousand people. Now, thanks to a significantly improved early warning system, it is possible to warn the population of coastal cities in advance of approaching hurricanes.

Catastrophic waves caused by landslides and rock falls are relatively rare. They arise as a result of the fall of large blocks of rock into deep-sea bays; in this case, a huge mass of water is displaced, which falls on the shore. In 1796, a landslide came down on the island of Kyushu in Japan, which had tragic consequences: three huge waves generated by it claimed the lives of approx. 15 thousand people.

tides

Tides roll on the shores of the ocean, as a result of which the water level rises to a height of 15 m or more. The main cause of tides on the surface of the Earth is the attraction of the Moon. There are two high tides and two low tides every 24 hours and 52 minutes. Although these level fluctuations are only noticeable near the coast and in the shallows, they are known to manifest themselves in the open sea as well. Many very strong currents in the coastal zone are caused by tides, therefore, for safe navigation, sailors need to use special tables of currents. In the straits connecting the Inland Sea of ​​Japan with the open ocean, tidal currents reach a speed of 20 km / h, and in the Seymour-Narrows Strait off the coast of British Columbia (Vancouver Island) in Canada, a speed of approx. 30 km/h.

currents

Currents in the ocean can also be created by waves. Coastal waves approaching the shore at an angle cause relatively slow alongshore currents. Where the current deviates from the shore, its speed increases sharply - a discontinuous current is formed, which can be dangerous for swimmers. The rotation of the Earth causes major ocean currents to move clockwise in the Northern Hemisphere and counterclockwise in the Southern Hemisphere. Some currents have some of the richest fishing grounds, such as the Labrador Current off the east coast of North America and the Peruvian Current (or Humboldt) off the coast of Peru and Chile.

Turbid currents are among the strongest currents in the ocean. They are caused by the movement of a large volume of suspended sediment; these sediments can be carried by rivers, be the result of waves in shallow water, or be formed by a landslide on an underwater slope. Ideal conditions for the origin of such currents exist in the tops of submarine canyons located near the coast, especially at the confluence of rivers. Such currents develop speeds from 1.5 to 10 km / h and sometimes damage submarine cables. After the 1929 earthquake with its epicenter in the area of ​​the Great Newfoundland Bank, many transatlantic cables connecting Northern Europe and the USA were damaged, probably due to strong turbidity currents.

Shores and coastlines

The maps clearly show an extraordinary variety of coastlines. Examples include indented coastlines with islands and winding straits (in Maine, southern Alaska, and Norway); shores of relatively simple outline, as on much of the west coast of the United States; deeply penetrating and branching bays (for example, Chesapeake) in the middle part of the Atlantic coast of the USA; protruding low-lying coast of Louisiana near the mouth of the Mississippi River. Similar examples can be given for any latitude and any geographic or climatic region.

Shore evolution

First of all, let's look at how the sea level has changed over the past 18 thousand years. Just before that, most of the land at high latitudes was covered by huge glaciers. As these glaciers melted, melt water entered the ocean, as a result of which its level rose by about 100 m. At the same time, many river mouths were flooded - this is how estuaries were formed. Where glaciers have created valleys deepened below sea level, deep bays (fjords) have formed with numerous rocky islands, as, for example, in the coastal zone of Alaska and Norway. When attacking low-lying coasts, the sea also flooded the river valleys. On the sandy coasts, as a result of wave activity, low barrier islands were formed, stretched along the coast. Such forms are found off the southern and southeastern coasts of the United States. Sometimes barrier islands form accumulative coastal protrusions (for example, Cape Hatteras). At the mouths of rivers carrying a large amount of sediment, deltas appear. On tectonic block shores experiencing uplifts that compensated for sea level rise, rectilinear abrasion ledges (cliffs) can form. On the island of Hawaii, as a result of volcanic activity, lava flows flowed into the sea and lava deltas formed. In many places, the development of the coast proceeded in such a way that the bays formed during the flooding of the mouths of the rivers continued to exist - for example, the Chesapeake Bay or the bays on the northwestern coast of the Iberian Peninsula.

In the tropics, the rise in sea level promoted more intensive growth of corals on the outer (marine) side of the reefs, so that lagoons formed on the inner side, separating the barrier reef from the coast. A similar process also took place where, against the background of a rise in sea level, the island was submerged. At the same time, the barrier reefs on the outer side were partially destroyed during storms, and coral fragments were piled up by storm waves above calm sea level. Reef rings around submerged volcanic islands have formed atolls. In the last 2000 years, there has been practically no rise in the level of the World Ocean.

Beaches

Beaches have always been highly valued by man. They are composed mainly of sand, although there are also pebble and even small boulder beaches. Sometimes sand is a shell crushed by waves (the so-called shell sand). In the profile of the beach, sloping and almost horizontal parts stand out. The angle of inclination of the coastal part depends on the sand that composes it: on beaches composed of fine sand, the frontal zone is the most gentle; on coarse-grained sand beaches, the slopes are somewhat greater, and the steepest ledge is formed by pebble and boulder beaches. The rear zone of the beach is usually located above sea level, but sometimes huge storm waves flood it too.

There are several types of beaches. For the coasts of the United States, the most typical are long, relatively straight beaches, bordering the barrier islands from the outside. Such beaches are characterized by alongshore hollows, where currents dangerous for swimmers can develop. On the outer side of the hollows there are sand bars stretched along the coast, where the destruction of the waves occurs. With strong waves, discontinuous currents often occur here.

Irregularly shaped rocky shores usually form many small bays with small isolated stretches of beaches. These bays are often protected from the sea by rocks or underwater reefs protruding above the surface of the water.

On the beaches, formations created by waves are common - beach festoons, ripple marks, traces of wave splash, gullies formed during the runoff of water at low tide, as well as traces left by animals.

When beaches are washed out during winter storms, sand moves towards the open sea or along the coast. When the weather is calmer in summer, new masses of sand come to the beaches, brought by rivers or formed when coastal ledges are washed away by waves, and thus the beaches are restored. Unfortunately, this compensatory mechanism is often disrupted by human intervention. The construction of dams on rivers or the construction of bank protection walls prevents the flow of material to the beaches to replace the material washed away by winter storms.

In many places, sand is carried by waves along the coast, mainly in one direction (the so-called alongshore sediment flow). If coastal structures (dams, breakwaters, piers, groins, etc.) block this flow, then the beaches “upstream” (i.e., located on the side from which the sediment comes from) are either washed away by waves or expand beyond sediment input, while the "downstream" beaches are hardly fed by new sediments.

The relief of the bottom of the oceans

At the bottom of the oceans are huge mountain ranges, deep crevices with steep walls, extended ridges and deep rift valleys. In fact, the seabed is no less rugged than the land surface.

Shelf, continental slope and continental foot

The platform that fringes the continents and is called the continental shelf, or shelf, is not as flat as it was once believed. Rock ledges are common on the outer part of the shelf; Bedrock often comes out on the part of the continental slope adjacent to the shelf.

The average depth of the outer edge (edge) of the shelf separating it from the continental slope is approx. 130 m. Near the shores subjected to glaciation, hollows (troughs) and depressions are often noted on the shelf. So, off the fjord coasts of Norway, Alaska, and southern Chile, deep-water areas are found near the modern coastline; deep water troughs exist off the coast of Maine and in the Gulf of St. Lawrence. Glacier-carved troughs often run across the entire shelf; in some places along them there are shallows exceptionally rich in fish, for example, the banks of Georges or the Great Newfoundland.

Shelves off the coast, where there was no glaciation, have a more uniform structure, however, even on them sandy or even rocky ridges are often found, rising above the general level. During the Ice Age, when the level of the ocean dropped due to the fact that huge masses of water accumulated on land in the form of ice sheets, river deltas were created in many places of the present shelf. In other places on the outskirts of the continents, at the then sea level marks, abrasion platforms were cut into the surface. However, the results of these processes, which took place under the conditions of the low level of the World Ocean, were significantly transformed by tectonic movements and sedimentation in the subsequent post-glacial epoch.

The most surprising thing is that in many places on the outer shelf one can still find deposits that formed in the past, when the sea level was more than 100 m below the present. There are also found the bones of mammoths who lived in the Ice Age, and sometimes the tools of primitive man.

Speaking about the continental slope, the following features should be noted: firstly, it usually forms a clear and well-defined boundary with the shelf; secondly, it is almost always crossed by deep submarine canyons. The average angle of inclination on the continental slope is 4°, but there are also steeper, sometimes almost vertical sections. At the lower boundary of the slope in the Atlantic and Indian Oceans there is a gently sloping surface, called the "continental foot". Along the periphery of the Pacific Ocean, the continental foot is usually absent; it is often replaced by deep sea trenches, where tectonic movements (faults) generate earthquakes and where most tsunamis originate.

submarine canyons

These canyons, cut into the seabed for 300 m or more, are usually characterized by steep sides, a narrow bottom, and sinuosity in plan; like their land-based counterparts, they receive numerous tributaries. The deepest known underwater canyon, the Grand Bahama Canyon, is incised for almost 5 km.

Despite the similarity to the formations of the same name on land, the majority of submarine canyons are not ancient river valleys submerged below sea level. Turbid currents are quite capable of both working out a valley at the bottom of the ocean, and deepening and transforming a flooded river valley or a depression along a fault line. Submarine valleys do not remain unchanged; sediment transport is carried out along them, as evidenced by the signs of ripples on the bottom, and their depth is constantly changing.

deep sea trenches

Much has become known about the relief of the deep parts of the ocean floor as a result of large-scale research that unfolded after the Second World War. The greatest depths are confined to the deep-sea trenches of the Pacific Ocean. The deepest point - the so-called. "Challenger Deep" - is located within the Mariana Trench in the southwest Pacific Ocean. The following are the greatest depths of the oceans, with their names and locations:

• Arctic - 5527 m in the Greenland Sea;
• Atlantic - Puerto Rico Trench (off the coast of Puerto Rico) - 8742 m;
• Indian - Sunda (Yavansky) trench (west of the Sunda archipelago) - 7729 m;
• Quiet - the Mariana Trench (near the Mariana Islands) - 11,033 m; the Tonga trench (near New Zealand) - 10,882 m; Philippine Trench (near the Philippine Islands) - 10,497 m.

Mid-Atlantic Ridge

The existence of a large underwater ridge stretching from north to south across the central part of the Atlantic Ocean has long been known. Its length is almost 60 thousand km, one of its branches stretches into the Gulf of Aden to the Red Sea, and the other ends off the coast of the Gulf of California. The width of the ridge is hundreds of kilometers; its most striking feature is the rift valleys that can be traced along almost its entire length and resemble the East African rift zone.

An even more surprising discovery was that the main ridge is crossed at right angles to its axis by numerous ridges and hollows. These transverse ridges are traced in the ocean for thousands of kilometers. At the places where they intersect with the axial ridge, there are so-called. fault zones, which are associated with active tectonic movements and where the centers of large earthquakes are located.

A. Wegener's Continental Drift Hypothesis

Until about 1965, most geologists believed that the position and shape of the continents and ocean basins remained unchanged. There was a rather vague notion that the Earth was contracting, and that this contraction resulted in the formation of folded mountain ranges. When, in 1912, the German meteorologist Alfred Wegener proposed the idea that the continents were moving ("drifting") and that the Atlantic Ocean was formed in the process of widening a crack that split an ancient supercontinent, this idea was met with incredulity, despite a lot of evidence in its favor. (the similarity of the outlines of the eastern and western coasts of the Atlantic Ocean; the similarity of fossil remains in Africa and South America; traces of the great glaciations of the Carboniferous and Permian periods in the interval 350-230 million years ago in areas now located near the equator).

Growth (spreading) of the ocean floor. Gradually, Wegener's arguments were reinforced by the results of further research. It has been suggested that rift valleys within mid-ocean ridges originate as extensional fissures, which are then filled by rising magma from the depths. The continents and adjacent parts of the oceans form huge plates moving away from the underwater ridges. The frontal part of the American Plate is pushing against the Pacific Plate; the latter, in turn, moves under the mainland - a process called subduction occurs. There is a lot of other evidence in favor of this theory: for example, the confinement of earthquake centers, marginal deep-sea trenches, mountain ranges and volcanoes to these areas. This theory makes it possible to explain almost all major landforms of continents and ocean basins.

Magnetic anomalies

The most convincing argument in favor of the hypothesis of the expansion of the ocean floor is the alternation of bands of direct and reverse polarity (positive and negative magnetic anomalies), traced symmetrically on both sides of the mid-ocean ridges and running parallel to their axis. The study of these anomalies made it possible to establish that the spreading of the oceans occurs on average at a rate of several centimeters per year.

Plate tectonics

Another proof of the likelihood of this hypothesis was obtained with the help of deep-sea drilling. If, as follows from historical geology, the expansion of the oceans began in the Jurassic, no part of the Atlantic Ocean can be older than this time. Deep-sea boreholes have penetrated Jurassic deposits (formed 190–135 million years ago) in some places, but older ones have not been found anywhere. This circumstance can be considered weighty evidence; at the same time, it leads to the paradoxical conclusion that the ocean floor is younger than the ocean itself.

ocean research

Early research

The first attempts to explore the oceans were purely geographical in nature. Travelers of the past (Columbus, Magellan, Cook, etc.) made long tedious voyages across the seas and discovered islands and new continents. The first attempt to explore the ocean itself and its bottom was made by the British expedition on the Challenger (1872-1876). This voyage laid the foundations of modern oceanology. The echo sounding method, developed during the First World War, made it possible to compile new maps of the shelf and the continental slope. Special oceanological scientific institutions that appeared in the 1920s and 1930s extended their activities to deep-sea areas.

Modern stage

Real progress in research, however, begins only after the end of the Second World War, when the navies of various countries took part in the study of the ocean. At the same time, many oceanographic stations received support.

The leading role in these studies belonged to the USA and the USSR; on a smaller scale, similar work was carried out by Great Britain, France, Japan, West Germany and other countries. In about 20 years, it was possible to get a fairly complete picture of the topography of the ocean floor. On the published maps of the bottom relief, a picture of the distribution of depths emerged. The study of the ocean floor with the help of echo sounding, in which sound waves are reflected from the surface of bedrock buried under loose sediments, has also acquired great importance. Now more is known about these buried deposits than about the rocks of the continental crust.

Submersibles with a crew on board

A great step forward in ocean research was the development of deep-sea submersibles with portholes. In 1960, Jacques Picard and Donald Walsh, on the Trieste I submersible, dived in the deepest known area of ​​the ocean, the Challenger Deep, 320 km southwest of Guam. The "diving saucer" by Jacques-Yves Cousteau turned out to be the most successful among devices of this type; with its help, it was possible to discover the amazing world of coral reefs and underwater canyons to a depth of 300 m. Another apparatus, Alvin, descended to a depth of 3650 m (with a design diving depth of up to 4580 m) and was actively used in scientific research.

deep sea drilling

Just as the concept of plate tectonics revolutionized geological theory, deep sea drilling revolutionized the understanding of geological history. An advanced drilling rig allows you to pass hundreds and even thousands of meters in igneous rocks. If it was necessary to replace the blunt bit of this installation, a casing string was left in the well, which could be easily detected by a sonar mounted on a new drill pipe bit, and thus continue drilling the same well. Cores from deep-sea wells have made it possible to fill in many gaps in the geological history of our planet and, in particular, have provided much evidence for the correctness of the ocean floor spreading hypothesis.

ocean resources

As the planet's resources increasingly struggle to meet the needs of a growing population, the ocean is becoming increasingly important as a source of food, energy, minerals and water.

Ocean food resources

Tens of millions of tons of fish, shellfish and crustaceans are caught in the oceans every year. In some parts of the oceans, modern factory ship fishing is very intensive. Some species of whales are almost completely exterminated. Continued intensive fishing can cause severe damage to such valuable commercial fish species as tuna, herring, cod, sea bass, sardine, hake.

Fish farming

Large areas of the shelf could be singled out for fish breeding. At the same time, you can fertilize the seabed to ensure the growth of marine plants that feed on fish.

Mineral resources of the oceans

All the minerals that are found on land are also present in sea water. Salts, magnesium, sulfur, calcium, potassium, bromine are most common there. Recently, oceanologists have discovered that in many places the ocean floor is literally covered with a scattering of ferromanganese nodules with a high content of manganese, nickel and cobalt. Phosphorite concretions found in shallow water can be used as a raw material for the production of fertilizers. Sea water also contains valuable metals such as titanium, silver and gold. Currently, only salt, magnesium and bromine are extracted from sea water in significant quantities.

Oil

A number of large oil fields are already being developed on the shelf, for example, off the coast of Texas and Louisiana, in the North Sea, the Persian Gulf and off the coast of China. Exploration is ongoing in many other areas, such as off the coast of West Africa, off the east coast of the United States and Mexico, off the coast of Arctic Canada and Alaska, Venezuela and Brazil.

The ocean is a source of energy

The ocean is an almost inexhaustible source of energy.

Tidal energy

It has long been known that tidal currents passing through narrow straits can be used for energy in the same way as waterfalls and dams on rivers. Thus, for example, a tidal hydroelectric power station has been successfully operating in Saint-Malo in France since 1966.

Wave energy

Wave energy can also be used to generate electricity.

Thermal Gradient Energy

Nearly three-quarters of the solar energy that hits Earth comes from the oceans, so the ocean is the perfect giant heat sink. Energy generation, based on the use of the temperature difference between the surface and deep layers of the ocean, could be carried out on large floating power plants. Currently, the development of such systems is in the experimental stage.

Other resources

Other resources include pearls, which are formed in the body of some mollusks; sponges; algae used as fertilizers, food products and food additives, as well as in medicine as a source of iodine, sodium and potassium; deposits of guano - bird droppings mined on some atolls in the Pacific Ocean and used as fertilizer. Finally, desalination makes it possible to obtain fresh water from sea water.

ocean and man

Scientists believe that life originated in the ocean about 4 billion years ago. The special properties of water have had a huge impact on human evolution and still make life possible on our planet. Man used the seas as a way of trade and communication. Sailing the seas, he made discoveries. He turned to the sea in search of food, energy, material resources and inspiration.

Oceanography and Oceanology

Ocean research is often subdivided into physical oceanography, chemical oceanography, marine geology and geophysics, marine meteorology, ocean biology, and engineering oceanography. In most countries with access to the ocean, oceanographic research is being carried out.

International organizations

Among the most significant organizations involved in the study of the seas and oceans is the UN Intergovernmental Oceanographic Commission.

Related essay:

plan:

introduction
• 1Phase of the oceans
• 2 Research history
  • 2.1 Research methods
  • 2.2 Scientific organizations
  • 2.3 Museums and aquariums
• 3 Opening of the oceans
• 4 Geography of the oceans
  • 4.1 World ocean water
  • 4.2. Bottom development
  • 4.3 Sea currents
• 5Geologija
• 6Klima
• 7 Ecology
• 8 Economy
• 9Research the facts

introduction

World Ocean- the main part of the hydrosphere, which makes up 94.1% of its area, which is a continuous, but unbridled water of the earth's shell surrounding continents and islands, and is marked by a common salt composition.

Selin and large archipelagos divide the ocean of the world into five large parts (oceans):

• Atlantic Ocean
• Indian Ocean
• arctic ocean
• Pacific Ocean
• South ocean

The smaller oceans are known as seas, bays, straits, etc.

The land ocean doctrine is called Oceanology.

1. Origin of the oceans

The source of the oceans is a matter of hundreds of years of disputes.

They think the ocean is hot in the heat. Due to the high partial pressure of carbon dioxide in the atmosphere, it reaches 5 bar, its water is saturated with carbon dioxide, H2CO3 is acidified (pH ≈ 3-5).

This water dissolves a large number of different metals, especially iron in the form of FeCl2 chloride.

The activity of photosynthetic bacteria led to the appearance of oxygen in the atmosphere. It was taken up by the ocean and consumed to oxidize the iron dissolved in the water.

There is a hypothesis that from the silhouette of the Paleozoic and Mesozoic period up to the supercontinent Pangea, the ancient Pantal Ocean was surrounded, which covers about half of the world.

second

Research history

The first explorers were navigators. In the era of geographical discoveries, the continent, explored oceans and islands are described. The voyage of Magellan (1519-1522) and, as a result, the abolition of James Cook (1768-1780) allowed Europeans to get an idea of ​​the vast expanses of water that surrounds the continents of our planet, and to imagine the contours of the continents.

The first maps of the world were created. In the 17th and 18th centuries, the coastlines were detailed and the world map took on a modern look. However, the depths of the ocean have been poorly explored. In the middle of the 17th century, the Dutch geographer Bernhardus Varenius suggested using the term "water", "World Ocean".

December 22, 1872 from Portsmouth, Port Portland, set off on the ship "Challenger", specially equipped to participate in the first oceanographic cancellation.

In the second half of the 20th century, intensive study of the depths of the oceans began.

Using the echolocation method, detailed maps of the ocean depths were collected and the main landforms of the bottom in the ocean were discovered. These data, together with the results of geophysical and geological studies, led to the formation of the theory of tectonic tectonics in the late 60s. Tectonic plates are a modern geological theory of the movement of the lithosphere.

To study the structure of the oceanic crust, an international program was organized to study the seabed. One of the main results of the program was the confirmation of the theory.

2.1.

Research methods

• Ocean research in the 20th century was actively carried out on research ships. In some areas of the oceans, they performed regular flights. A significant contribution to science was the research of such national courts as Vityaz, academician Kurchatov, academician Mstislav Keldysh. Large international scientific experiments took place in the ocean of Polygon-70, MODE-I, POLYMODE.
• The study used Deep Sea vehicles such as Peaks, Mir, Trieste.

  In a survey of the Trieste bathyscaphe in 1960, a dive was recorded at Marian Dietsch. One of the most important scientific results of diving is the discovery of highly organized life at such depths.

• Late 1970s. The development of the first specialized oceanographic satellites (SEASAT in the USA, Cosmos-1076 in the USSR) began.
• On April 11, 2007, the Chinese satellite "Haiyan-1B" ("Ocean 1B") began to study the color and temperature of the sea.

• In 2006, NASA's Jason 2 satellite began work on the International Oceanic Ocean Topography Mission (OSTM) project to study global ocean circulation and global sea level fluctuations.

• By July 2009, Canada had built one of the largest scientific complexes for the study of the oceans.

2.2.

Scientific organizations

• AARI
• VNIIOkeangeologiya
• Institute of Oceanology. P. P. Shirshov RAS
• Institute of the Pacific. VI Ilyichev from the Far Eastern Branch of the Russian Academy of Sciences.
• Scripps Research Institute of California.

2.3. Museums and aquariums

• Museum of the World Ocean
• Oceanographic Museum of Monaco

There are only 3 aquariums in Russia: "Planet Neptune" in St. Petersburg, "Aquamir" in Vladivostok and an aquarium in Sochi.

The construction of aquariums in Moscow began.

To date, there are several views on the division of the global ocean, taking into account hydrophysical and climatic characteristics, water characteristics, biological factors, etc.

Already in the XVIII-XIX. There were several such versions. Conrad Malta-Brunet and Charles de Fleurier divided the two oceans. In particular, Philippe Beuchet and Henry Steenfens proposed to divide it into three parts.

The Italian geographer Adriano Balbi (1782-1878) identified four regions in the oceans: the Atlantic, north and south of the North Sea and the Great Ocean, part of which became the modern Indian (this division is due to the inability to determine the exact boundaries between the Indian and Pacific oceans and the similarity zoogeographical conditions of these regions).

Today we often talk about the Indo-Pacific region, located in the area of ​​​​the tropical zoogeography of this area, which includes the tropical Indians and the Pacific Ocean, as well as the Red Sea. The border area runs along the coast of Africa at the Cape of Needles and then from the Yellow Sea on the northern coast of New Zealand and the Southern California Tropic of Capricorn.

In 1953, the International Hydrogeographic Bureau developed a new division of the world ocean, which was then finally granted to the Arctic, Atlantic, Indian and Pacific oceans.

fourth

Geography of the oceans

General physical and geographical data:

• Average temperature: 5°C;
• Medium pressure: 20 MPa;
• Average density: 1.024 g/cm3;
• Average depth: 3730 m;
• Total weight: 1.4 × 1021 kg;
• Total volume: 1370 million km3;
• pH: 8.1 ± 0.2.

The deepest point of the ocean is the Marianas Ditches, located in the Pacific Ocean off the Northern Mariana Islands.

its greatest depth. 11,022 m was explored in 1951 by the British submarine Challenger II, after which the deepest part of the basin was named Challenger Deep.

4.1.

Waters of the World Ocean

The oceans lead to most of the Earth's hydrosphere - the oceanosphere. In the ocean, it is more than 96% (1,338 billion cubic meters). From the water of the earth. The volume of fresh water entering the ocean with river flow and precipitation does not exceed 0.5 million cubic kilometers, which corresponds to a water layer in an area of ​​about 1.25 m. This leads to insensitivity of the salt composition of sea water and insignificant changes in density.

The unity of the ocean as a water mass is ensured by constant movement in the horizontal and vertical directions. In the ocean, as in the atmosphere, there are no sharp natural boundaries, they are all more or less gradual. The global mechanism of energy transformation and metabolism is maintained here, supported by uneven warming of surface waters and the atmosphere with the help of solar radiation.

4.2.

Below is the relief

The systematic study of the ocean floor began with the advent of the echo sounder. Most of the ocean floor is flat surfaces, the so-called abyssal plane.

Their average depth is 5 km. In the central parts of all oceans of 1-2 km there are linear rises - the central ocean reefs, which are connected to one network. The reefs are divided by the transformation of faults into segments that appear in low elevation relief perpendicular to the crest.

In the absolute plains there are many lonely mountains, some of which are divided above the surface of the water in the form of islands. Most of these hills are extinct or active volcanoes.

Under the weight of the mountain, the oceanic crust sways and the mountains slowly sink into the water. There is a coral reef that creates a peak, which results in a ring island of corals - an atol.

If the continent is passive, then between it and the ocean there is an underwater part - the underwater part of the continent and the continental slope, which smoothly turns into the plain of the abyss.

Before subduction, areas where trees of oceanic crust are under continents that contain ditches, the deepest parts of the oceans.

4.3. sea ​​currents

Sea currents - the movement of large ocean waters - have serious consequences for the climate of many regions of the world.

5. Geology

Main article - Marine geology.

sixth

The ocean plays an important role in shaping the Earth's climate. Under the influence of solar radiation, water evaporates and is transported to the continents, where it enters in the form of various atmospheric precipitation. Ocean currents carry heated or cooled water to other latitudes and are largely responsible for the distribution of heat around the planet.

Water has a huge heat capacity, so the temperature of the ocean changes much more slowly than the temperature of air or soil.

Areas near the ocean have lower diurnal and seasonal differences in temperature.

If the factors causing the currents are constant, a constant current is generated, and if they are episodic, a short-term random current is generated. In the predominant direction, the streams are divided into a meridian, which directs its waters to the north or south, and an area that extends in breadth.

Currents whose water temperature is higher than the average temperature for the same latitude are called hot, cold currents, and currents that have the same temperature as the surrounding waters are neutral.

The direction of flow in the world's oceans is affected by the repulsive force caused by the rotation of the Earth, the Coriolis force. In the northern hemisphere, the branches flow to the right, and in the south they flow to the left. On average, the flow velocity does not exceed 10 m / s, and the depth does not exceed 300 m.

seventh

ecology

The ocean is the living space of many life forms; among them:

• Kites like whales and dolphins
• Cephalopods such as octopus, squid
• Shellfish such as lobster, shrimp, wings
• sea ​​worms
• plankton
• coral
• seaweed

Decreased ozone concentrations in the stratosphere over Antarctic waters cause lower ocean uptake of carbon dioxide, which compromises the exoskeletons of calcium and mollusk, molluscs and crustaceans.

eighths

economy

The oceans are of great importance for transport, with many ships being transported by ship between the world's ports. For transportation of a unit of cargo per unit of distance, maritime transport is one of the cheapest, but not the fastest.

Canals were built to reduce the length of the sea, most notably Panama and Suez.

9. Interesting facts

• To warm the oceans to a boil, energy is needed, which is released during the decay of 6.8 gigans of uranium.
• If you take all the ocean water (1.34 billion km3) and make a ball, you get a planet with a diameter of about 1400 km.

remarks

links

Exhibitions and openings

• For the secrets of Neptune / Science.

  Edition and after. A. A. Aksenov. - Moscow: Mizel, 1976. - 399 p. — (XX century: travel, discoveries, research).

oceanology

• Wegener A. Origin of continents and oceans / Trans. with him. P. G. Kaminsky, ur. P. N. Kropotkin. - L .: Nauka, 1984. - 285 p.
• Stepanov V.N. Okeanosfera.

  — M.: Mizel, 1983. — 270 p.

• Shamraev Yu.I., Shishkina L.A. Oceanology. - L .: Gidrometeoizdat, 1980. - 382 p.
• Gusev A.M. Fundamentals of Oceanology. - Moscow: Publishing House of Moscow State University, 1983.
• Gusev A.M. Antarctica. Oceans and Atmosphere .. - M .: Education, 1983. - 151 p.

• Moiseev P.

  A. Biological resources of the oceans. - 2nd ed. — M.: Agropromizdat, 1989. — 366 p. — ISBN 5-10-000265-4

• Zakharov L.A. Introduction to commercial oceanography. - Kaliningrad, 1998.

  - 83 seconds.

general information

• Dictionary of the geographical encyclopedia / Ch. Edition A. F. Treshnikov. - 2nd ed., Issue. - Moscow: Soviet Encyclopedia, 1989 - 591 p.

World map showing the oceans in blue.

Pangea surrounded by the super-ocean of Panthalassa

Bathyscaphe "Trieste"

The average annual surface temperature of the World Ocean

Alignment of the geoid (EGM96) with an idealized figure of the Earth (WGS84 ellipsoid).

We can see that the surface of the World Ocean is not completely smooth, for example in the north Indian Ocean - it drops 100 meters and rises ~80 meters in the western Pacific.

Message "Ocean"

Point one. The concept of the oceans. What is the World Ocean? This is the totality of all known seas and oceans of our planet, in other words, the marine water shell of our planet Earth. More than 95 percent of the water on Earth is in the oceans. Alas, you can’t drink it, since the seas and oceans of the Earth are salty waters.

They surround the continents of the Earth. A great many islands are scattered in the World Ocean, large, huge, small and very tiny, inhabited and uninhabited by man.

Point two. Five or four oceans of the Earth. The world ocean includes five or four oceans - scientists have no consensus on this issue.

These are the Atlantic, Pacific (Great) oceans, Indian and Arctic oceans. According to another classification, there is also the Southern Ocean on the planet.

The maximum depth of water in the ocean is more than 11 km - this is much more than the height of the highest mountain on Earth, that is, Everest.

Such a depth was noted in the abyss of the Mariana Trench in the Pacific Ocean.

Point three. We all came from the oceans? The world ocean is the cradle of life on Earth, according to the main version of biologists, life on the planet originated once, in time immemorial, in the ocean.

And later, living beings came to land and adapted to life on land.

Point four. Pollution of the oceans and other environmental "shortcomings". The oceans and seas of the world are explored by oceanologists. Today they talk about the environmental problems associated with the oceans. Firstly, this is the pollution of the oceans - plastic garbage that is swallowed by fish, chemical waste from the coastal industry, which poisons all living things in the ocean.

And, of course, oil spilled from tankers while transporting this type of fuel. This is the most dangerous pollution of sea and ocean waters: massively, smeared with oil, seabirds die, fish and marine animals are poisoned by oil poisons over vast territories. One wrecked oil tanker can devastate an entire region!

Also, the level of the World Ocean is now rising due to global warming on Earth, which is due to the fault of people.

A rise in the level of the World Ocean only up to 5 cm can lead to catastrophic consequences: flooding of coastal zones, entire cities and resort areas in different countries, large floods.

Therefore, it is important for people to prevent global warming on the planet.

The world ocean, which is the entire sea and oceans of the Earth, has a great influence on the life of the planet. A huge mass of ocean water forms the climate of the planet and serves as a source of precipitation. This produces more than half of the oxygen and regulates the amount of carbon dioxide in the atmosphere as it can absorb the excess. The accumulation and transformation of a large mass of mineral and organic matter occurs at the bottom of the World Ocean, and the geological and geochemical processes occurring in the oceans and seas have strongly influenced the entire earth's crust.

The Pope became the cradle of life on Earth; now lives about 4/5 of all living things on the planet.

1. World Ocean and its parts

We once called our planet Earth even though it looked blue from space. This color is explained by the fact that ¾ of the planet's surface is covered with a continuous water cover - with oceans and seas - and only a little more than ¼ of the earth's share.

The surface of the World Ocean and the Earth is qualitatively different, but they are not separated: among them is a constant exchange of matter and energy. A huge role in this exchange belongs to the circle of water in nature.

The world ocean is one, although it is strongly divided. Its surface is 361 million.

km². The average depth of the world's oceans is about 4000 meters - this is only 0.0007 the radius of the world. The ocean, given that the density of its water is close to 1, and the density of the solid body of the Earth is about 5.5, we have only a small part of the mass of our planet. The world ocean is divided into four main parts: the Pacific, Atlantic, Indian and Arctic oceans.

Since there is a constant exchange of water between them, the distribution of the World Ocean into parts is largely conditioned and turns into historical changes.

Then the oceans are divided into parts. They have seas, bays and straits.

The parts of the ocean that come into the country and are separated from the ocean from the islands or peninsula, as well as the heights of the underwater landscape, are called seas.

The surface of the sea is called the water area. Part of the sea area of ​​a certain width, which extends along the national belt, is called territorial water. They are part of this situation.

International law does not allow the extension of territorial waters above 12 nautical miles (1 nautical mile is 1852 meters). The 12-mile connection has been recognized by about 100 countries, including our own, and by 22 countries that have arbitrarily established wider territorial waters.

Outside the territorial waters, it is the high seas, which is generally used in all countries.

The part of the sea or ocean that penetrates deep into the earth, but communicates freely with it, is called a bay. With its water features, currents and living organisms, bays are usually very different from the sea and oceans.

Parts of the oceans are connected with narrower ones. Narrower - a relatively wide water area, which is limited on both sides by the coasts of continents, islands or peninsulas.

The width of the strait is very different.

Thus, the global ocean, as part of the hydrosphere, consists of oceans, seas and strains. All are connected.

2. Problems of the world ocean

Man is a child of nature, his whole life conforms to his laws and regulations, but we must not draw attention to the growing negative impact of economic activity on the environment. Changes are taking place on an ever-increasing scale due to deforestation, plowing of large areas, hydrotechnical measures affecting river flow and groundwater regimes, the introduction of large amounts of river, groundwater and lake water, and pollution in particular.

Accordingly, it changes the liquid, gaseous and solid flow into the seas and oceans. Sea water is polluted due to the dumping of various wastes, garbage and impurities from ships, unfortunately, frequent accidents. In the Pacific Ocean, about 9 million tons of waste is dumped every year during the flight stages, in the Atlantic Ocean - more than 30 million tons.

Oceans and seas are polluted with such harmful substances as oil, heavy metals, pesticides, radioisotopes. In March 1995, the bodies of 324 dolphins and 8 whales were found in the Gulf of California.

According to experts, the main cause of the tragedy was the influence of these substances. Gaseous toxic substances, such as carbon monoxide, sulfur dioxide, enter the atmosphere from sea water. According to Caltech calculations, 50,000 tons of lead enters the oceans every year in the world's oceans, raining in the air with car exhaust. In places close to the sea coast, sea water often reveals pathogenic microflora.

The level of pollution is constantly increasing. The water's self-cleaning capacity is sometimes insufficient to deal with the ever-increasing amount of waste. Under the influence of currents, pollution mixes and spreads very quickly, negatively affecting areas rich in animals and vegetation, which causes serious damage to the state of marine ecosystems. Humanity is killing.

3. Protecting the oceans

The most serious problem of the seas and oceans in our century is oil pollution, the consequences of which are catastrophic for all life on Earth.

That is why an international conference was organized in London in 1954 to develop coordinated measures to protect the marine environment from oil pollution.

He adopted a convention defining the responsibilities of countries in this area. Later, in 1958, four more documents were adopted in Geneva: on the high seas, on the territorial sea and the adjacent zone, on the continental shelf, on fisheries and on the conservation of living marine resources. These conventions were legally enshrined in the principles and norms of maritime law. Each country is obliged to develop and enforce laws prohibiting the pollution of the marine environment by oils, radioactive waste and other harmful substances.

A conference held in London in 1973 adopted documents on the prevention of pollution from ships. In accordance with the adopted Convention, each ship must have a certificate - evidence that the hull, mechanisms and other equipment are in good condition and do not cause damage to the seabed.

Compliance with certificates is verified by checking at the port of entry.

It is forbidden to drain oil from tankers, all emissions from them must be exhausted only at coastal points. Electrochemical plants have been established to treat and decontaminate ship waste, including household waste. The Institute of Oceanology of the Russian Academy of Sciences has developed an emulsion method for cleaning tanks, which completely exclude oil from entering the water area. It consists of the addition of several surfactants to the wash water (ML formulation) which allows the vessel to be cleaned without releasing contaminated water or oily residues, which can then be reclaimed for further use.

Each tanker can carry up to 300 tons of oil.

To prevent oil leakage, the oil tanker is planned to be improved. Many modern tankers have a double bottom. If one of them is damaged, the oil does not spill, the other shell holds it.

In particular, logbooks, shipmasters must record information on all oil and oil products operations to indicate the place and time of delivery or discharges from a contaminated sewage vessel.

Floating oil spreaders and side barriers are used to systematically clean water surfaces from accidental spills. Physico-chemical methods are also used to prevent the spread of oil. We have created a group of foams that are completely scalded when in contact with oil. After the foam, the foam can be reused as a sorbent. Such drugs are very suitable for their ease of use and low costs, but their mass production has not yet been established.

There are also sorbents based on vegetable, mineral and synthetic substances. Some can collect up to 90% of spilled oil. The main requirement for them is irreversibility.

When oil is collected by sorbents or mechanical means, a thin film is left on the surface of the water, which can be removed by spraying chemical products that decompose them.

These substances must be biologically pure.

In Japan, a unique technology has been developed and tested, thanks to which a huge city can be removed in a short time. Kansai Sange Corporation has prepared the ASWW reagent, the main ingredient of which is a specially processed rice shell. Broken across the surface, the drug absorbs the ejection within half an hour and turns it into a thick mass that can be pulled out with a simple mesh.

The original cleaning method is confirmed by American scientists in the Atlantic Ocean. Under the oil film, the ceramic plate falls to a certain depth. An acoustic panel is connected to it. Under vibration, it is first collected at the plate installation site, and then mixed with water and flashes. An electric current brought to the stove, a lit fountain, and the oil is completely burned.

To remove oil stains from the surface of coastal waters, American scientists have created a modification of polypropylene that attracts fat particles.

On the cascades of the ship between the buildings, they pulled out some kind of curtain from this material, the ends of which hang in the water. When the cutter is hit in place, the oil adheres well to the "curtains". The rest of the polymer passes only through the cylinders of a special device that presses the oil into the prepared container.

Since 1993, the dumping of liquid radioactive waste (LRW) has been banned, but the number is constantly increasing. To protect the environment, in the 1990s, we began to develop projects for the treatment of LRW.

In 1996, representatives of Japanese, American and Russian companies signed a contract for the creation of a plant for the processing of LRW, located in the Far East of Russia. The Japanese government allocated $25.2 million. USA to complete the project.

Despite some progress in finding effective means of eliminating pollution, it is premature to talk about a solution to the problem.

Only by introducing new methods of cleaning water surfaces, we cannot guarantee the cleanliness of the seas and oceans. The main challenge that all countries must address is the prevention of pollution.

Answer left guest

I think that the ocean of the world provides the planet with oxygen, especially since the main source of oxygen on Earth is not reproduced by forests, but blue - with green algae - living in the ocean.
This largely determines the shape of the planet as a whole, including the climate, the water cycle on Earth. In the ocean, vital shipping routes connect continents and islands.

Its biological resources are enormous. There are more than 160 thousand species of animals and about 10 thousand species of algae in the World Ocean. Annually, the repetition of commercial fish is estimated at 200 million tons, of which about 1/3. More than 90% of the world's production comes from the coastal shelf, especially in the temperate and high latitudes of the northern hemisphere. The share of the Pacific Ocean in the world catch is about 60%, the Atlantic - about 35%. On the shelf of the World Ocean there are large reserves of oil and gas, large reserves of ferromanganese ores and other minerals.

Mankind is just beginning to use the energy resources of the world, including tidal and tidal energies.

The oceans make up 94% of the hydrosphere. With the desalination of sea water, the solution of many water problems in the future is connected. Unfortunately, humanity does not always wisely use the natural resources of the oceans.

Today at the lesson of the world around me, I made a presentation on the topic "Oceans and seas in human life."

We live in the center of Russia, and the seas and oceans are far from us, but, nevertheless, they are of great importance in our life.

Placethe origin of life.

There is a theory that all life on earth originated in the oceans. Including the person. Water is not only the source of life, but also the most important element for its maintenance.

This is the ocean.

It plays an important role in our life.

2. Food source.

The seas and oceans are the place where a person receives food. The seafood we eat includes: fish, shrimp, squid, mussels, edible seaweed, lobster, octopus, crabs, lobsters, sea salt, oysters, scallops.

Most of the dishes that are prepared from these products are delicacies. Sea food contains vitamins A, B, C and D, and is also rich in iodine, bromine, calcium and phosphorus, which are essential for the human body. Every year people consume 100 million tons of seafood.

3. Climate.

Ocean currents significantly affect the climate on the continents, so the way of life of people also depends on them.

The dry climate in the desert and the humid climate in the jungle also depend on the proximity of the ocean.

4. Movement and movement.

Sea routes are used to transport passengers and goods.

5. Minerals.

At the bottom of the oceans there are deposits of minerals in large volumes.

For example, at the bottom of the Arctic Ocean there is a lot of oil and
gas.

6. Health.

The sea is a place of healing. The maritime climate favorably affects human health: the skin, respiratory and nervous systems, and also strengthens the immune system.

7. Recreation and entertainment.

Sea cruises and travel are popular all over the world, as well as boating,
catamarans and water skiing.

Study.

The world ocean is not well studied yet. Scientific expeditions are organized to study its expanses and inhabitants.

9. Sport.

Rowing, sailing and other water activities are very popular and are included in the program of the Summer Olympic Games.

10. Jewelry materials.

Pearls that grow in sea shells are used to make velor jewelry.

Beads and earrings are made from corals.

11. Fleet basing and border protection.

Sections of the sea coast are used for the parking of ships and vessels, including military ones, which are the force for protecting the state's maritime borders.

If my report about the seas and oceans helps you a little in your studies, please put a link to my blog in your social network. After all, I tried.