World Ocean, area with seas 91.6 million km 2; average depth 3926 m; water volume 337 million m3. Includes: Mediterranean seas (Baltic, North, Mediterranean, Black, Azov, Caribbean with the Gulf of Mexico), less isolated seas (in the North - Baffin, Labrador; near Antarctica - Scotia, Weddell, Lazarev, Rieser-Larsen), large bays (Guinea , Biscay, Hudson, Above Lawrence). Islands of the Atlantic Ocean: Greenland (2176 thousand km 2), Iceland (103 thousand km 2), (230 thousand km 2), Greater and Lesser Antilles (220 thousand km 2), Ireland (84 thousand km 2), Cape Verde (4 thousand km 2), Faroe (1.4 thousand km 2), Shetland (1.4 thousand km 2), Azores (2.3 thousand km 2), Madeira (797 km 2), Bermuda (53.3 km 2) and others (See map).
Historical sketch. The Atlantic Ocean has been an object of navigation since the 2nd millennium BC. In the 6th century BC. Phoenician ships sailed around Africa. Ancient Greek navigator Pytheas in the 4th century BC. sailed to the North Atlantic. In the 10th century AD. Norman navigator Eric the Red explored the coast of Greenland. During the Age of Great Geographical Discovery (15-16 centuries), the Portuguese explored the route to the Indian Ocean along the coast of Africa (Vasco da Gama, 1497-98). The Genoese H. Columbus (1492, 1493-96, 1498-1500, 1502-1504) discovered the islands of the Caribbean Sea and. In these and subsequent voyages, the outlines and nature of the coasts were established for the first time, coastal depths, directions and speeds of currents, and climatic characteristics of the Atlantic Ocean were determined. The first soil samples were obtained by the English scientist J. Ross in the Baffin Sea (1817-1818 and others). Determinations of temperature, transparency and other measurements were carried out by expeditions of Russian navigators Yu. F. Lisyansky and I. F. Krusenstern (1803-06), O. E. Kotzebue (1817-18). In 1820, Antarctica was discovered by the Russian expedition of F. F. Bellingshausen and M. P. Lazarev. Interest in studying the relief and soils of the Atlantic Ocean increased in the mid-19th century due to the need to lay transoceanic telegraph cables. Dozens of vessels measured depths and took soil samples (American vessels "Arctic", "Cyclops"; English - "Lighting", "Porcupine"; German - "Gazelle", "Valdivia", "Gauss"; French - "Travaeur", " Talisman", etc.).
A major role in the study of the Atlantic Ocean was played by the British expedition on the ship Challenger (1872-76), based on the materials of which, using other data, the first relief and soils of the World Ocean were compiled. The most important expeditions of the 1st half of the 20th century: German on the Meteor (1925-38), American on the Atlantis (30s), Swedish on the Albatross (1947-48). In the early 50s, a number of countries, primarily and, launched extensive research into the geological structure of the Atlantic Ocean floor using precision echo sounders, the latest geophysical methods, and automatic and controlled underwater vehicles. Extensive work has been carried out by modern expeditions on the ships “Mikhail Lomonosov”, “Vityaz”, “Zarya”, “Sedov”, “Equator”, “Ob”, “Akademik Kurchatov”, “Akademik Vernadsky”, “Dmitry Mendeleev”, etc. 1968 Deep-sea drilling began on board the American vessel Glomar Challenger.
Hydrological regime. In the upper thickness of the Atlantic Ocean, 4 large-scale gyres are distinguished: the Northern Cyclonic Gyre (north of 45° north latitude), the anticyclonic gyre of the Northern Hemisphere (45° north latitude - 5° south latitude), the anticyclonic gyre of the Southern Hemisphere (5° south latitude - 45° south latitude), Antarctic circumpolar current of cyclonic rotation (45° south latitude - Antarctica). On the western periphery of the gyres there are narrow but powerful currents (2-6 km/h): Labrador - Northern Cyclonic Gyre; Gulf Stream (the most powerful current of the Atlantic Ocean.), Guiana Current - Northern Anticyclonic Gyre; Brazilian - Southern Anticyclonic Gyre. In the central and eastern regions of the ocean, currents are relatively weak, with the exception of the equatorial zone.
Bottom waters are formed when surface waters sink in polar latitudes (their average temperature is 1.6°C). In some places they move at high speeds (up to 1.6 km/h) and are capable of eroding sediments and transporting suspended material, creating underwater valleys and large bottom accumulative landforms. Cold and low-salinity bottom Antarctic waters penetrate along the bottoms of basins in the western regions of the Atlantic Ocean to 42° north latitude. The average surface temperature of the Atlantic Ocean is 16.53°C (the South Atlantic is 6°C colder than the North). The warmest waters with an average temperature of 26.7°C are observed at 5-10° northern latitude (thermal equator). Toward Greenland and Antarctica, the water temperature drops to 0°C. The salinity of the waters of the Atlantic Ocean is 34.0-37.3 0/00, the highest water density is over 1027 kg/m 3 in the northeast and south, decreasing to 1022.5 kg/m 3 towards the equator. Tides are predominantly semidiurnal (maximum 18 m in the Bay of Fundy); in some areas mixed and daily tides of 0.5-2.2 m are observed.
Ice. In the northern part of the Atlantic Ocean, ice forms only in the inland seas of temperate latitudes (the Baltic, North and Azov seas, the Gulf of St. Lawrence); a large amount of ice and icebergs are carried out from the Arctic Ocean (Greenland and Baffin seas). In the South Atlantic Ocean, ice and icebergs form off the coast of Antarctica and in the Weddell Sea.
Relief and geological structure. Within the Atlantic Ocean, there is a powerful mountain system stretching from north to south - the Mid-Atlantic Ridge, which is an element of the global system of Mid-Ocean Ridges, as well as deep-sea basins and (map). The Mid-Atlantic Ridge extends over 17 thousand km at a latitude of up to 1000 km. Its ridge in many areas is dissected by longitudinal gorges - rift valleys, as well as transverse depressions - transform faults, which break it into separate blocks with a latitudinal displacement relative to the ridge axis. The relief of the ridge, highly dissected in the axial zone, levels out towards the periphery due to the burial of sediments. Shallow-focus epicenters are localized in the axial zone along the ridge crest and in areas. Along the outskirts of the ridge there are deep-sea basins: in the west - Labrador, Newfoundland, North American, Brazilian, Argentine; in the east - European (including Icelandic, Iberian and Irish Trench), North African (including Canary and Cape Verde), Sierra Leone, Guinean, Angolan and Cape. Within the ocean floor, abyssal plains, hill zones, uplifts and seamounts are distinguished (map). Abyssal plains stretch in two intermittent stripes in the continental parts of deep-sea basins. These are the flattest areas of the earth's surface, the primary relief of which is leveled by sediments with a thickness of 3-3.5 km. Closer to the axis of the Mid-Atlantic Ridge, at a depth of 5.5-6 km, there are zones of abyssal hills. Oceanic rises are located between the continents and the mid-ocean ridge and separate the basins. The largest uplifts: Bermuda, Rio Grande, Rockall, Sierra Leone, Whale Ridge, Canary, Madeira, Cape Verde, etc.
There are thousands of seamounts known in the Atlantic Ocean; almost all of them are probably volcanic structures. The Atlantic Ocean is characterized by unconformable cutting of the geological structures of the continents by the coastline. The depth of the edge is 100-200 m, in the subpolar regions 200-350 m, the width is from several kilometers to several hundred kilometers. The most extensive shelf areas are off the island of Newfoundland, in the North Sea, the Gulf of Mexico and off the coast of Argentina. The shelf topography is characterized by longitudinal grooves along the outer edge. The continental slope of the Atlantic Ocean has a slope of several degrees, a height of 2-4 km, and is characterized by terrace-like ledges and transverse canyons. Within the sloping plain (continental foot), the “granite” layer of the continental crust is pinched out. The transition zone with a special crustal structure includes the marginal deep-sea trenches: Puerto Rico (maximum depth 8742 m), South Sandwich (8325 m), Cayman (7090 m), Oriente (up to 6795 m), within which they are observed as shallow-focus, and deep-focus earthquakes (map).
The similarity of the contours and geological structure of the continents surrounding the Atlantic Ocean, as well as the increase in the age of the basalt bed, the thickness and age of sediments with distance from the axis of the mid-ocean ridge, served as the basis for explaining the origin of the ocean within the framework of the concept of Mobilism. It is assumed that the North Atlantic formed in the Triassic (200 million years ago) during the separation of North America from North-West Africa, the South - 120-105 million years ago during the separation of Africa and South America. The connection of the basins occurred about 90 million years ago (the youngest age of the bottom - about 60 million years - was found in the Northeast of the southern tip of Greenland). Subsequently, the Atlantic Ocean expanded with constant new formation of the crust due to outpourings and intrusions of basalts in the axial zone of the mid-ocean ridge and its partial subsidence into the mantle in the marginal trenches.
Mineral resources. Among the mineral resources of the Atlantic Ocean, gas is also of great importance (map to the station of the World Ocean). North America has oil and gas reserves in the Labrador Sea, the bays of St. Lawrence, Nova Scotia, and Georges Bank. Oil reserves on the eastern shelf of Canada are estimated at 2.5 billion tons, gas reserves at 3.3 trillion. m 3, on the eastern shelf and continental slope of the USA - up to 0.54 billion tons of oil and 0.39 trillion. m 3 gas. More than 280 fields have been discovered on the southern shelf of the United States, and more than 20 fields off the coast (see). More than 60% of Venezuela's oil is produced in the Maracaibo Lagoon (see). The deposits of the Gulf of Paria (Trinidad Island) are actively exploited. The total reserves of the Caribbean Sea shelves amount to 13 billion tons of oil and 8.5 trillion. m 3 gas. Oil and gas bearing areas have been identified on the shelves (Toduz-yc-Santos Bay) and (San Xopxe Bay). Oil fields have been discovered in the North (114 fields) and Irish Seas, the Gulf of Guinea (50 on the Nigerian shelf, 37 off Gabon, 3 off Congo, etc.).
The forecast oil reserves on the Mediterranean shelf are estimated at 110-120 billion tons. There are known deposits in the Aegean, Adriatic, Ionian seas, off the coast of Tunisia, Egypt, Spain, etc. Sulfur is mined in the salt dome structures of the Gulf of Mexico. With the help of horizontal underground workings, coal is extracted from coastal mines in the offshore extensions of continental basins - in the UK (up to 10% of national production) and Canada. Off the eastern coast of the island of Newfoundland is the largest iron ore deposit of Waubana (total reserves of about 2 billion tons). Tin deposits are being developed off the coast of Great Britain (Cornwall peninsula). Heavy minerals (,) are mined off the coast of Florida, in the Gulf of Mexico. off the coast of Brazil, Uruguay, Argentina, the Scandinavian and Iberian Peninsulas, Senegal, and South Africa. The shelf of South-West Africa is an area of industrial diamond mining (reserves 12 million). Gold placers have been discovered off the Nova Scotia Peninsula. found on the US shelves, on the Agulhas Bank. The largest fields of ferromanganese nodules in the Atlantic Ocean are located in the North American Basin and on the Blake Plateau near Florida; their extraction is not yet profitable. The main sea routes in the Atlantic Ocean, along which mineral raw materials are transported, mainly developed in the 18th and 19th centuries. In the 1960s, the Atlantic Ocean accounted for 69% of all maritime traffic, except for floating vessels; pipelines are used to transport oil and gas from offshore fields to the shore. The Atlantic Ocean is increasingly being polluted by petroleum products, industrial wastewater from enterprises, containing toxic chemicals, radioactive and other substances that harm marine flora and fauna, are concentrated in marine food products, posing a great danger to humanity, which requires taking effective measures to preventing further pollution of the ocean environment.
TABLE OF CONTENTS
INTRODUCTION
The scientific direction of ocean geography, which emerged as an independent branch of geographical science in the second half of the twentieth century, was officially approved in the decisions of the V and VI Congresses of the Geographical Society of the USSR (1970, 1975) and the I All-Union Conference on Ocean Geography (1983). The main tasks of ocean geography were the study of general geographic patterns within the oceanosphere, the establishment of specific dependencies between natural conditions and ocean ecosystems, between natural resources and the ocean economy, as well as the identification of anomalous regimes of rational environmental management.Physical geography of the ocean deals with the study of the spatial structure and basic physical properties of the ocean as a single natural system, on the one hand, and as part of a more general planetary system - the biosphere - on the other hand. Its tasks include identifying the relationships between the nature of the ocean and continents, large-scale connections between the oceanosphere and the rest of the elements of the Earth’s geographic shell, processes of energy and mass exchange between them, and other phenomena.
The twentieth century, especially its last quarter, was marked by a very intensive increase in anthropogenic impact on the natural environment, which caused an environmental crisis on Earth, which continues in our time. This process covered not only land, but also the World Ocean, especially inland and marginal seas adjacent to economically developed countries. The Atlantic Ocean bears most of the anthropogenic load.
The above circumstances determine the relevance of the chosen topic. Object of study at work is the Atlantic Ocean, subject- its natural resources.
Purpose of the work– analyze the natural resources of the Atlantic. To achieve this goal, we set the following tasks:
- give a general description of the Atlantic Ocean;
- analyze the properties of waters, the composition of flora and fauna, and also pay attention to the minerals of the ocean;
- reveal the features and problems of ocean development.
This work will be useful to everyone who is interested in issues of oceanology, as well as environmental management.
CHAPTER 1. CHARACTERISTICS OF THE ATLANTIC OCEAN
1.1.Geographical location, climatic and hydrological conditions
The Atlantic Ocean is the most studied and developed by people. It got its name from the titan Atlas (according to Greek mythology, holding the vault of heaven on his shoulders). At different times it was called differently: “The Sea beyond the Pillars of Hercules”, “Atlantic”, “Western Ocean”, “Sea of Darkness”, etc. The name "Atlantic Ocean" first appeared in 1507 on Wald-Seemüller's map, and since then the name has become established in geography.The boundaries of the Atlantic Ocean along the shores of the continents (Eurasia, Africa, the Americas and Antarctica) are natural, with other oceans (the Arctic, Pacific and Indian) - largely conditional.
The Atlantic Ocean borders the Arctic Ocean at 70° N. w. (Baffin Island - Disko Island), then from Cape Brewster (Greenland) along the Icelandic-Farrer threshold to 6° N. w. (Scandinavian Peninsula); with the Pacific Ocean - from about. Oste (Terra del Fuego) to Cape Sternek (Antarctic Peninsula); with the Indian Ocean - 20° east. from Cape Agulhas to Antarctica. The rest of the ocean is limited by the coastlines of Eurasia, Africa, North and South America, and Antarctica (Fig. 1). The given boundaries are officially accepted in our country and are indicated in the Atlas of the Oceans (publishing house of the Ministry of Defense of the USSR and the Navy, 1980). Within the designated limits, the ocean area is 93.4 million km 2, the volume of water is 322.7 million km 3. Water exchange occurs in 46 years, which is 2 times faster than in the Pacific Ocean.
The significant role of the Atlantic in people’s lives is largely explained by purely geographical circumstances:
a large extent (from the Arctic to the Antarctic) between four continents, and it separates mainly flat areas on the continents that are convenient for human settlement and have long been developed by them;
the fact that large and medium-sized rivers flow into the ocean (Amazon, Congo, Niger, Mississippi, St. Lawrence, etc.), which served and serve as natural routes of communication;
the highly rugged coastline of Europe, the presence of the Mediterranean Sea and the Gulf of Mexico, which contributed to the development of navigation and ocean exploration.
The Atlantic Ocean has several seas: the Baltic, Mediterranean, Black, Marble, Azov, Caribbean and 3 large bays: Mexico, Biscay and Guinea. The largest islands - Great Britain and Ireland - are located off the coast of Europe. Particularly large clusters of islands are located off the coast of Central America: the Greater and Lesser Antilles, the Bahamas; off the coast of South America - Falkland, in the southern part of the ocean - South Orkney and South Sandwich; off the coast of Africa - the Canaries, Cape Verde, Azores, Madeira, Principe, Sao Tome, etc. In the axial zone of the ocean are the islands of Iceland, Ascension, St. Helena, Tristan da Cunha, on the border with the Arctic Ocean - The largest island on Earth is Greenland.
The climates of the Atlantic are largely determined by its large meridional extent, the peculiarities of the formation of the pressure field, and the unique configuration (there are more water areas in temperate latitudes than in equatorial-tropical latitudes). On the northern and southern outskirts there are huge regions of cooling and the formation of centers of high atmospheric pressure. Constant areas of low pressure in subequatorial and temperate latitudes and high pressure in subtropical latitudes are also formed over the ocean.
These are the Equatorial and Antarctic depressions, the Icelandic minimum, the North Atlantic (Azores) and South Atlantic maximums 1.
In the southern hemisphere, where the surface of the ocean is interrupted by land only in relatively small areas, all the main pressure systems are extended along the equator in the form of sublatitudinal belts separated by frontal zones, and during the year they only slightly shift following the sun towards the summer hemisphere.
In the winter of the southern hemisphere, the southeast trade wind penetrates to the equator and slightly further north, towards the Gulf of Guinea and northern South America. The main precipitation at this time falls in the northern hemisphere, and dry weather prevails on both sides of the Southern Tropic. South of 40° S. The western transport is active, winds blow, often reaching gale force, thick clouds and fogs are observed, and heavy precipitation falls in the form of rain and snow. These are the “roaring forties” latitudes. From Antarctica, in high latitudes, southeastern and eastern winds blow, with which icebergs and sea ice are blown to the north.
In the warm half of the year, the main directions of air flow remain the same, but the equatorial trough expands to the south, the southeast trade wind intensifies, rushing into an area of low pressure over South America, and precipitation falls along its eastern coast. Western winds in temperate and high latitudes remain the dominant atmospheric process.
Natural conditions in the subtropical and temperate latitudes of the North Atlantic differ significantly from those characteristic of the southern part of the ocean. This is due both to the characteristics of the water area itself and to the size of the land bordering it, the temperature and air pressure above which change sharply throughout the year. The most significant contrasts in pressure and temperature are created in winter, when high pressure centers form over ice-covered Greenland, North America and the interior of Eurasia due to cooling and the temperature not only over land, but also over the ice-clogged interisland waters of the Canadian Arctic Archipelago is very low . The ocean itself, with the exception of the coastal northwestern part, even in February maintains a surface water temperature of 5 to 10 °C. This is due to the influx of warm waters from the south into the northeastern part of the Atlantic and the lack of cold water from the Arctic Ocean.
In the north of the Atlantic Ocean, a closed area of low pressure is formed in winter - the Icelandic, or North Atlantic, minimum. Its interaction with the Azores (North Atlantic) maximum, located at the 30th parallel, creates a predominant westerly wind flow over the North Atlantic, carrying moist-unstable relatively warm air from the ocean to the Eurasian continent. This atmospheric process is accompanied by precipitation in the form of rain and snow at positive temperatures. A similar situation applies to the ocean area south of 40° N. and in the Mediterranean, where it rains at this time.
In the summer season of the northern hemisphere, the high pressure area remains only over the Greenland ice sheet, low pressure centers are established over the continents, and the Icelandic low weakens. Western transport remains the main circulation process in temperate and high latitudes, but it is not as intense as in winter. The Azores High intensifies and expands, and most of the North Atlantic, including the Mediterranean Sea, is under the influence of tropical air masses and does not receive precipitation. Only off the coast of North America, where moist, unstable air enters along the periphery of the Azores High, does monsoon-type precipitation occur, although this process is not at all as pronounced as on the Pacific coast of Eurasia.
In summer and especially in autumn, tropical hurricanes arise over the Atlantic Ocean between the northern tropic and the equator (as in the Pacific and Indian oceans at these latitudes), which sweep over the Caribbean Sea, the Gulf of Mexico, Florida with enormous destructive force, and sometimes penetrate far to the north, up to 40° N
Due to the high solar activity observed in recent years off the coast of the Atlantic Ocean, the frequency of tropical hurricanes has increased significantly. In 2005, three hurricanes hit the southern coast of the United States - Katrina, Rita and Emily, the first of which caused enormous damage to the city of New Orleans.
1.2.Bottom topography
The Mid-Atlantic Ridge runs across the entire ocean (at approximately equal distances from the continental coasts) (Fig. 2).The outlines of the shores of the Atlantic Ocean are extremely remarkable. If Africa and South America, Europe and North America are moved close to each other on the map, so that their coastlines coincide, then the contours of the continents will converge, like two halves of a torn ruble. This coincidence in the outlines of the coasts led some scientists to a rather simple and original conclusion that the listed continents used to form a single supercontinent, in which a giant crack arose under the influence of the Earth’s rotation. America separated from Europe and Africa and drifted along viscous deep rocks to the west, and the depression that formed between them filled with water and turned into the Atlantic Ocean.
Later, when it was established that a huge mountain system, the Mid-Atlantic Ridge, stretched from north to south in the Atlantic Ocean, it was not so easy to explain the origin of the Atlantic Ocean depression by the drift of America. The question arose: if America sailed from Africa, then where did the ridge 300-1500 kilometers wide, the peaks of which rise 1500-4500 meters above the ocean bed, come from between them? Maybe there was no continental drift? Maybe the waves of the Atlantic are walking over the flooded continents? This is precisely the opinion held by most geologists.
But the more information accumulated about the structure of the mysterious ridge, the details of the bottom topography and the rocks composing it, the clearer the complexity and seriousness of the problem became to scientists. This was further aggravated by the fact that the scientific data obtained often gave rise to contradictory judgments.
In the process of studying the ocean, it turned out that along the axis of the Mid-Atlantic Ridge there runs a deep valley - a crack that cuts the ridge along almost its entire length. Such valleys usually arise under the influence of tectonic extensional forces and are called rift valleys. They are zones of active manifestation of tectonics, seismicity and volcanism in the geological history of the Earth. The discovery of a rift valley on the ocean floor was reminiscent of a giant crack in a hypothetical supercontinent and continental drift. However, this new information and, above all, the relief features of the ridge required a different explanation of the mechanism of continental drift.
Schematically, the Mid-Atlantic Ridge is now represented as a symmetrical mountain structure, where the rift valley serves as the axis of symmetry. It is interesting that earthquakes occurring in the Atlantic Ocean are mostly associated with the Mid-Atlantic Ridge, and most of them are confined to the rift valley. Examining the relief of the ridge and pieces of rocks raised from the bottom, scientists noticed a pattern that surprised them in the geological structure of this mountain structure, namely: the further - be it to the west or east - from the rift valley, the older the bottom topography and the more ancient the mountain rocks become rocks that make up the mysterious underwater mountainous country. Thus, basalt rocks recovered by geologists from the crest of a ridge and from a rift valley, as a rule, are several hundred thousand years old; some basalt samples are several million years old, but not more than five million. In geological terms, these rocks are young. On the flanks of the ridge the basalts are much older than on the ridge; their age reaches 30 million years or more. Even further from the axis of symmetry, closer to the continents, the age of rocks raised from the ocean floor is determined to be 70 million years. It is important to note that no rocks older than 100 million years have been found in the Atlantic Ocean, while on land the oldest rocks are more than three billion years old.
The given information about the age of ocean rocks allows us to consider the Mid-Atlantic Ridge as a fairly young rock formation, which continues to develop and change to this day.
The Atlantic Ocean is second in size only to the Pacific. It is distinguished from other oceans by its highly rugged coastline, forming numerous seas and bays, especially in the northern part. In addition, the total area of river basins flowing into this ocean or its marginal seas is significantly larger than that of rivers flowing into any other ocean. Another difference of the Atlantic Ocean is the relatively small number of islands and the complex bottom topography, which, thanks to underwater ridges and rises, forms many separate basins.
The Atlantic Ocean is located in all climate zones of the Earth. The main part of the ocean is between 40° N latitude. and 42° S – located in subtropical, tropical, subequatorial and equatorial climatic zones. There are high positive air temperatures here all year round. The most severe climate is found in sub-Antarctic and Antarctic latitudes, and to a lesser extent in subpolar and northern latitudes.
CHAPTER 2. NATURAL RICHES OF THE ATLANTIC OCEAN
2.1.Waters and their properties
The zoning of water masses in the ocean is complicated by the influence of land and sea currents. This is manifested primarily in the temperature distribution of surface waters. In many areas of the ocean, isotherms off the coast deviate sharply from the latitudinal direction.The northern half of the ocean is warmer than the southern half, the temperature difference reaches 6°C. The average surface water temperature (16.5°C) is slightly lower than in the Pacific Ocean. The cooling effect is exerted by the waters and ice of the Arctic and Antarctic.
In sub-equatorial latitudes there are two trade wind currents - the Northern Trade Wind and the Southern Trade Wind, moving from east to west. Between them, the Intertrade Countercurrent moves east. The Northern Trade Wind Current passes near 20° N latitude. and off the coast of North America it gradually deviates to the north. The Southern Trade Wind Current, passing south of the equator from the coast of Africa to the west, reaches the eastern protrusion of the South American continent and at Cape Cabo Branco it divides into two branches running along the coast of South America. Its northern branch (Guiana Current) reaches the Gulf of Mexico and, together with the North Trade Wind Current, takes part in the formation of the system of warm currents of the North Atlantic. The southern branch (Brazil Current) reaches 40° S, where it meets a branch of the circumpolar current of the Western Winds - the cold Falkland Current. Another branch of the Western Winds current, carrying relatively cold waters to the north, enters the Atlantic Ocean off the southwestern coast of Africa. This Benguela Current is an analogue of the Peruvian Current of the Pacific Ocean. Its influence can be traced almost to the equator, where it flows into the South Trade Wind Current, closing the southern Atlantic gyre and significantly reducing the temperature of surface waters off the coast of Africa.
The overall picture of surface currents in the North Atlantic is much more complex than in the southern part of the ocean.
A branch of the North Trade Wind Current, strengthened by the Guiana Current, penetrates through the Caribbean Sea and the Yucatan Strait into the Gulf of Mexico, causing a significant increase in water levels there compared to the ocean. As a result, a powerful waste current arises, which, rounding Cuba, emerges through the Strait of Florida into the ocean called the Gulf Stream (“stream from the gulf”). This is how the greatest system of warm surface currents in the World Ocean originates off the southeastern coast of North America.
Gulf Stream at 30° N latitude. and 79°W merges with the warm Antilles Current, which is a continuation of the North Trade Wind Current. The Gulf Stream then passes along the edge of the continental shelf to approximately 36°N. At Cape Hatteras, deviating under the influence of the Earth's rotation, it turns east, skirting the edge of the Great Newfoundland Bank, and goes to the shores of Europe under the name of the North Atlantic Current, or “Gulf Stream Drift”.
When leaving the Strait of Florida, the width of the Gulf Stream reaches 75 km, its depth is 700 m, and the current speed is from 6 to 30 km/h. The average surface water temperature is 26 °C. After merging with the Antilles Current, the width of the Gulf Stream increases 3 times, and the water flow is 82 million m 3 /s, i.e. 60 times higher than the flow of all rivers on the globe.
North Atlantic Current at 50°N. and 20°W is divided into three branches. The northern one (Irminger Current) goes to the southern and western shores of Iceland, and then goes around the southern coast of Greenland. The main middle branch continues to move northeast, towards the British Isles and the Scandinavian Peninsula, and goes into the Arctic Ocean called the Norwegian Current. The width of its flow north of the British Isles reaches 185 km, depth – 500 m, flow speed – from 9 to 12 km per day. The surface water temperature is 7... 8 °C in winter and 11... 13 °C in summer, which is on average 10 °C higher than at the same latitude in the western part of the ocean. The third, southern, branch penetrates the Bay of Biscay and continues south along the Iberian Peninsula and the northeastern coast of Africa in the form of the cold Canary Current. Flowing into the North Trade Wind Current, it closes the subtropical gyre of the North Atlantic.
The northwestern part of the Atlantic Ocean is mainly influenced by cold waters coming from the Arctic, and different hydrological conditions develop there. In the area of the island of Newfoundland, the cold waters of the Labrador Current move towards the Gulf Stream, pushing the warm waters of the Gulf Stream away from the northeastern coast of North America. In winter, the waters of the Labrador Current are 5...8 °C colder than the Gulf Stream; all year round their temperature does not exceed 10 °C; they form a so-called “cold wall”. The convergence of warm and cold waters promotes the development of microorganisms in the upper layer of water and, consequently, the abundance of fish. The Great Newfoundland Bank is especially famous in this regard, where cod, herring, and salmon are caught.
To approximately 43°N. The Labrador Current carries icebergs and sea ice, which, combined with the fogs characteristic of this part of the ocean, pose a great danger to shipping. A tragic illustration is the disaster of the Titanic, which sank in 1912 800 km southeast of Newfoundland.
The water temperature on the surface of the Atlantic Ocean, as in the Pacific, is generally lower in the southern hemisphere than in the northern. Even at 60° N latitude. (with the exception of the northwestern regions), the surface water temperature fluctuates throughout the year from 6 to 10 °C. In the southern hemisphere at the same latitude it is close to 0 °C and in the eastern part it is lower than in the western.
The warmest surface waters of the Atlantic (26...28 °C) are confined to the zone between the equator and the Northern Tropic. But even these maximum values do not reach the values observed at the same latitudes in the Pacific and Indian Oceans.
The salinity of the surface waters of the Atlantic Ocean is much more varied than in other oceans. The highest values (36-37%o - the maximum value for the open part of the World Ocean) are characteristic of subtropical regions with low annual precipitation and strong evaporation. High salinity is also associated with the influx of salt water from the Mediterranean Sea through the shallow Strait of Gibraltar. On the other hand, large areas of the water surface have average oceanic and even low salinity. This is due to large amounts of atmospheric precipitation (in equatorial regions) and the desalination effect of large rivers (Amazon, La Plata, Orinoco, Congo, etc.). In high latitudes, a decrease in salinity to 32-34%o, especially in summer, is explained by the melting of icebergs and floating sea ice.
The structural features of the North Atlantic basin, the circulation of the atmosphere and surface waters in subtropical latitudes determined the existence here of a unique natural formation called the Sargasso Sea (Fig. 2). This mysterious area of almost stagnant water lies in the southwestern part of the North Atlantic, between Bermuda and the West Indies. This sea got its name from the Portuguese word “saggaco”, which means “seaweed”. Almost stagnant, but clean and warm water is inhabited by sargassum algae, which are able to live and reproduce afloat (Fig. 3). Thanks to them, conditions here are more reminiscent of a tidal zone rather than an open ocean. Microscopic plankton do not live here because the water temperature is too high.
2.2.Flora
Ocean vegetation is very diverse. Phytobenthos (bottom vegetation) occupies about 2% of the bottom area and is distributed on the shelf to a depth of 100 m. It is represented by green, brown, red algae and some higher plants. The tropical ocean zone has a high species diversity, but a small amount of biomass compared to cold and temperate geographic zones. The northern littoral zone is characterized by brown algae, and the sublittoral zone by kelp. Red algae and some types of sea grass are found. Green algae are very common in the tropical zone. Various types of sea lettuce are the largest in size. Among the red algae, porphyry, rhodolinia, chaidrus, and ahnfeltia are widely represented. For many animals, free-floating sargassum algae, typical of the Sargasso Sea, form a unique biotope. Of the brown algae in the sublittoral zone in the northern part of the ocean, giant representatives of Macrocystis are characteristic. Phytoplankton, unlike phytobenthos, develops throughout the entire body of water. In the cold and temperate zones of the ocean it is concentrated at a depth of up to 50 m, and in the tropical zone - up to 80 m. It is represented by 234 species. Important representatives of phytoplankton are silicon algae, characteristic of temperate and circumpolar regions. In these areas, silicon algae represent more than 95% of the total phytoplankton. Near the equator the amount of algae is insignificant. The mass of phytoplankton ranges from 1 to 100 mg/m3, and in the high latitudes of the Northern and Southern Hemispheres during the period of mass development (sea bloom) it reaches 10 g/m3 or more.2.3.Fauna
The fauna of the Atlantic Ocean is rich and diverse. Animals inhabit the entire thickness of ocean water. The diversity of fauna increases towards the tropics. In polar and temperate latitudes they number thousands of species, in tropical latitudes - tens of thousands.Temperate and cold waters are inhabited by large marine mammals - whales and pinnipeds, fish - herring, cod, perch and flounder; in zooplankton there is a sharp predominance of copepods and sometimes pteropods. There is great similarity between the faunas of the temperate zones of both hemispheres. More than 100 species of animals are bipolar, that is, they live only in cold and temperate zones, these include seals, fur seals, whales, sprat, sardines, anchovies, and many invertebrates, including mussels. The tropical waters of the Atlantic Ocean are characterized by: sperm whales, sea turtles, crustaceans, sharks, flying fish, crabs, coral polyps, scyphoid jellyfish, siphonophores, radiolarians. There are also many dangerous inhabitants: sharks, barracudas, moray eels. There are urchin fish and invertebrate sea urchins, the pricks of which are very painful.
The world of corals is very unique, but the coral structures of the Atlantic are insignificant in comparison with the Pacific Ocean. At a depth of about 4 m off the coast of Cuba, a “sea fan” coral lives, which has the appearance of burdock-shaped leaves penetrated by a network of vessels - this is the soft coral Gongonaria, forming entire thickets - “underwater forests”.
The deep-sea regions of the Atlantic, like other oceans, represent a special environment of enormous pressure, low temperatures and eternal darkness. Here you can find crustaceans, echinoderms, annelids, silicon sponges, and sea lilies.
In the Atlantic, there is also an “ocean desert” (“ocean Sahara”) - this is the Sargasso Sea, where the biomass value is no more than 25 mg/m 3, which is primarily due, apparently, to the special gas regime of the sea.
2.4. Minerals
A large number of offshore oil and gas fields have been discovered in the Atlantic Ocean and its seas and are being intensively developed. The richest offshore oil and gas areas in the world include: the Gulf of Mexico, the Maracaibo Lagoon, the North Sea, and the Gulf of Guinea, which are being intensively developed. Three large oil and gas provinces have been identified in the Western Atlantic: 1) from Davis Strait to the latitude of New York (industrial reserves near Labrador and south of Newfoundland); 2) on the Brazilian shelf from Cape Calcañar to Rio de Janeiro (more than 25 fields have been discovered); 3) in the coastal waters of Argentina from the Gulf of San Jorge to the Strait of Magellan. According to estimates, promising oil and gas areas make up about 1/4 of the ocean, and the total potential recoverable oil and gas resources are estimated at more than 80 billion tons. The largest iron ore deposit of Waubana is located off the east coast of the island of Newfoundland (total reserves are about 2 billion tons). Tin deposits are being developed off the coast of Great Britain and Florida. Heavy minerals (ilmenite, rutile, zircon, monazite) are mined off the coast of Florida, in the Gulf of Mexico. off the coast of Brazil, Uruguay, Argentina, the Scandinavian and Iberian Peninsulas, Senegal, and South Africa. The shelf of South-West Africa is an area of industrial diamond mining (reserves of 12 million carats). Gold placers have been discovered off the Nova Scotia Peninsula. Phosphorites were found on the shelves of the USA, Morocco, Liberia, and on the Agulhas Bank. Diamond deposits were discovered off the coast of South-West Africa on the shelf in sediments of ancient and modern rivers. Ferromanganese nodules were found in bottom basins off the coasts of Florida and Newfoundland 2 . Coal, barite, sulfur, sand, pebbles and limestone are also mined from the seabed.Like the entire World Ocean, the Atlantic is characterized by an abundance of biomass with a relative poverty of the species composition of the organic world in temperate and high latitudes and much greater species diversity in the intertropical space and subtropics.
Zooplankton includes copepods (krill) and pteropods, while phytoplankton is dominated by diatoms. The corresponding latitudes of the northern part of the Atlantic Ocean (North Atlantic biogeographical region) are characterized by the presence in the organic world of the same groups of living organisms as in the southern hemisphere, but they are represented by other species and even genera. And compared to the same latitudes of the Pacific Ocean, the North Atlantic is distinguished by greater species diversity. This is especially true for fish and some mammals. Many areas of the North Atlantic have long been and continue to be places of intense fishing. Cod, herring, halibut, sea bass, and sprat are caught on banks off the coast of North America, in the North and Baltic seas. Since ancient times, mammals have been hunted in the Atlantic Ocean, especially seals, whales and other marine animals. This led to a severe depletion of the Atlantic's fishing resources compared to the Pacific and Indian oceans.
etc.............
South Atlantic Ocean. This includes areas adjacent to the east coast of South America and the southwest coast of Africa, as well as the Antarctic regions, with a total area
more than 40 million km 2 , of which only about 3 million km 2 (7.5%)
occupied by depths of less than 1000 m, and the largest shallow water plateau (about 1.4 million km 2) called the Patagonian-Falkland shelf, adjacent to the Atlantic coast of Uruguay and Argentina. The large latitudinal extent, which includes both warm subtropical and cold Antarctic zones, leaves its mark on the commercial fauna, represented here by both warm water (tuna, marlin, swordfish, scienes, sardines, etc.) and cold water (blue whiting, merluea, notothenia, silverfish, toothfish, etc.) inhabitants. The intensity of fishing here is quite high only on the southwestern and southern coasts of Africa, where in some years (1968-1970) sardines (up to 1.7 million tons), anchovies (0.4-0.6 million tons) and hake (0.5-0.7 million tons), while on the Patagonian shelf, the raw materials of which make it possible to produce at least 5-6 million tons of fish, the fishery is extremely poorly developed (only about 1.0 million tons). The total catch within the South Atlantic in recent years alone has reached 4 million tons, while the possible catch exceeds 10 million tons.
The Antarctic regions are of significant importance for fishing, where whales, seals, some fish, squid live in commercial quantities, and the resource of the abundant planktonic crustacean, Arctic krill, has a particularly great potential commercial importance.
Summarizing the current assessment of the used biological resources in the Atlantic Ocean and the possible prospects for the further development of fisheries, it should be considered that in this basin the catch of traditional fisheries by all countries can be increased from 23 - 25 to 35 million tons
The Soviet Union produced 3.5 million tons in the Atlantic Ocean basin, i.e. a significant portion (39%) of its marine fish catches, and in recent years Russia has been eyeing this vast region
as the most important for the implementation of sea and ocean fishing,
Lecture No. 9 Topic: "Raw materials of the Pacific Ocean."
Pacific Ocean. The Pacific Ocean basin makes up half
(176.7 million km 2 - 49.8%) of the entire water area of the World Ocean. The predominant part of its surface (80.8%) is located above depths from
3000 to 6000 m and only 8.7% (15.5 million km 2) is occupied by relatively shallow depths (less than 1000 m) and in this respect it is significantly inferior to the Atlantic, where about 15% is in shallow areas.
The greatest ruggedness of the coastline and the largest sections of the shelf are characteristic of the northern and western parts of the ocean (4.5 million km 2), where the Bering, Okhotsk, Japanese, Yellow, East and South China seas, etc. are located, as well as areas adjacent to the Indonesian archipelago. In addition, the shelf zones of Australia, New Zealand and Tasmania are quite extensive (more than 2 million km 2). Along the Pacific coast of North and esp. but the South American shelf is poorly developed. The oceanological regime of the Pacific Ocean is significantly influenced by a system of currents that creates several large-scale frontal zones and gyres in the northern and southern parts of the ocean.
Unlike the Atlantic, the northern part of the Pacific is connected to the Arctic Ocean basin by the narrow and shallow Bering Strait, and Pacific waters cannot warm the seas of the corresponding sector of the Arctic (East Siberian, Chukotka, etc.), which are characterized as low-productive. Here, only cod (polar cod) can be considered as a relatively abundant commercial fish.
The Pacific Ocean basin provides more than 53 million tons (6%) of global marine production. However, the relatively weak development of shallow waters leads to the fact that the catches here are sharply dominated by pelagic (89^) rather than bottom-dwelling objects, while in the Atlantic Ocean basin the share of the latter is much higher. Its modern fish productivity (300 kg/km) exceeded that of the Atlantic Ocean (250 kg/km) and many times
higher than the Indian one (60 kg/km), and there are still opportunities for further development of fishing for traditional objects within its limits.
Coastal marine placers rich in ilmenite, rutile, zircon and monocyte are represented by large deposits on the coasts of Brazil and the Florida Peninsula (USA). On a smaller scale, minerals of this type are concentrated off the coast of Argentina, Uruguay, Denmark, Spain, and Portugal. Tin-bearing and ferruginous sands are found on the Atlantic coast of North America and Europe, and coastal-marine placers of diamonds, gold, and platinum are found off the coast of South-West Africa (Angola, Namibia, South Africa). On the shelf of the Atlantic coast of North and South America and Africa (Blake Plateau, off Morocco, Liberia, etc.) phosphorite formations and phosphate sands (the extraction of which is still unprofitable due to lower quality compared to terrestrial phosphorites) have been discovered. Extensive fields of ferromanganese nodules are located in the northwestern part of the ocean, in the North American Basin and on the Blake Plateau. The total reserves of ferromanganese nodules in the Atlantic Ocean are estimated at 45 billion tons. The level of concentration of non-ferrous metals in them (with a low manganese content) is close to that of ore-bearing land rocks. A large number of offshore oil and gas fields have been discovered in the Atlantic Ocean and its seas and are being intensively developed. The richest offshore oil and gas areas in the world include the Gulf of Mexico, the Maracaibo Lagoon, the North Sea, and the Gulf of Guinea, which are being intensively developed. Three large oil and gas provinces have been identified in the Western Atlantic: 1) from Davis Strait to the latitude of New York (industrial reserves near Labrador and south of Newfoundland); 2) on the Brazilian shelf from Cape Calcañar to Rio de Janeiro (more than 25 fields have been discovered); 3) in the coastal waters of Argentina from the Gulf of San Jorge to the Strait of Magellan. According to estimates, promising oil and gas areas make up about 1/4 of the ocean, and the total potential recoverable oil and gas resources are estimated at more than 80 billion tons. Some areas of the Atlantic shelf are rich in coal (Great Britain, Canada), iron ore (Canada, Finland) .
24. Transport system and ports of the Atlantic Ocean.
A leading place among other sea basins in the world. The world's largest oil cargo flow from the Persian Gulf countries on its way to the Atlantic is divided into two branches: one goes around Africa from the south and heads to Western Europe, North and South America, and the other through Suez. Oil from North African countries to Europe and, partially, to North America, from the Gulf of Guinea countries to the USA and Brazil. From Mexico and Venezuela to the USA via the Caribbean Sea, and from Alaska via the Panama Canal to ports on the Atlantic coast. Liquefied gas from North African countries (Algeria, Libya) to Western Europe and the USA. In dry bulk transportation - iron ore (from Brazilian and Venezuelan ports to Europe), grain (from the USA, Canada, Argentina - to European ports), phosphorites (from the USA (Florida), Morocco - Western Europe), bauxite and alumina (from Jamaica, Suriname and Guyana in the USA), manganese (from Brazil, West and South Africa), chrome ore (from South Africa and the Mediterranean), zinc and nickel ores (from Canada), timber cargo (from Canada, Scandinavian countries and northern ports Russia to Western Europe). General cargo, which is 2/3 transported by liner vessels. Universal ports with a high level of mechanization. Western Europe - 1/2 of cargo turnover. The English Channel to the Kiel Canal, the east coast of Great Britain, Mediterranean port complexes along the coast of the Gulf of Lyon and the Ligurian Sea. USA from Gulf of Maine to Chesapeake Bay: New York - New Jersey, Ameriport and Hampton Rhodes. The Gulf of Mexico, where there are three main port-industrial complexes (New Orleans and Baton Rouge; Galveston Bay and the Houston Canal; the ports of Beaumont, Port Arthur, and Orange connected to the Gulf of Mexico by canals through Lake Sabine). oil (Amuay, Cartagena, Tobruk) and chemical (Arzev, Alexandria, Abidjan) factories, aluminum (Belen, San Luis, Puerto Madryn), metallurgy (Tubaran, Maracaibo, Warrij), cement (Freeport) industries. the southeastern coast of Brazil (Santos, Rio de Janeiro, Victoria) and in the Gulf of La Plata (Buenos Aires, Rosario, Santa Fe). (Port Harcourt, Lagos, Niger Delta). North African ports are wide open to the sea, and their universal nature requires significant costs to modernize the port facilities (Algeria, Tripoli, Casablanca, Alexandria and Tunisia). On a number of Caribbean islands (Bahamas, Cayman, Virgin Islands), the deepest transshipment terminals for large tankers (400 - 600 thousand deadweight tons) in this part of the ocean have been built.
To the question: Resources of the ATLANTIC OCEAN? given by the author Nasopharynx the best answer is Mineral Resources. Among the mineral resources of the Atlantic Ocean, the most important are oil and gas (map to the station. World Ocean). North America has oil and gas shelves in the Labrador Sea, the bays of St. Lawrence, Nova Scotia, and Georges Bank. Oil reserves on the eastern shelf of Canada are estimated at 2.5 billion tons, gas reserves at 3.3 trillion. m3, on the eastern shelf and continental slope of the USA - up to 0.54 billion tons of oil and 0.39 trillion. m3 of gas. More than 280 fields have been discovered on the southern shelf of the United States, and more than 20 fields off the coast of Mexico (see Gulf of Mexico oil and gas basin). More than 60% of Venezuela's oil is produced in the Maracaibo Lagoon (see Maracaibo oil and gas basin). The deposits of the Gulf of Paria (Trinidad Island) are actively exploited. The total reserves of the Caribbean Sea shelves amount to 13 billion tons of oil and 8.5 trillion. m3 of gas. Oil and gas bearing areas have been identified on the shelves of Brazil (Toduz-yc-Santos Bay) and Argentina (San Xopxe Bay). Oil fields have been discovered in the North (114 fields) and Irish Seas, the Gulf of Guinea (50 on the Nigerian shelf, 37 off Gabon, 3 off Congo, etc.).
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Mineral resources. Among the mineral resources of the Atlantic Ocean, the most important are oil and gas (map to the station. World Ocean). North America has oil and gas shelves in the Labrador Sea, the bays of St. Lawrence, Nova Scotia, and Georges Bank. Oil reserves on the eastern shelf of Canada are estimated at 2.5 billion tons, gas reserves at 3.3 trillion. m3, on the eastern shelf and continental slope of the USA - up to 0.54 billion tons of oil and 0.39 trillion. m3 of gas. More than 280 fields have been discovered on the southern shelf of the United States, and more than 20 fields off the coast of Mexico (see Gulf of Mexico oil and gas basin). More than 60% of Venezuela's oil is produced in the Maracaibo Lagoon (see Maracaibo oil and gas basin). The deposits of the Gulf of Paria (Trinidad Island) are actively exploited. The total reserves of the Caribbean Sea shelves amount to 13 billion tons of oil and 8.5 trillion. m3 of gas. Oil and gas bearing areas have been identified on the shelves of Brazil (Toduz-yc-Santos Bay) and Argentina (San Xopxe Bay). Oil fields have been discovered in the North (114 fields) and Irish Seas, the Gulf of Guinea (50 on the Nigerian shelf, 37 off Gabon, 3 off Congo, etc.).
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Valentin Bibik Student (193) 1 year ago
Natural resources: oil and gas deposits, fish, marine mammals (pinnipeds and whales), sand and gravel mixtures, placer deposits, ferromanganese nodules, precious stones
Definition: This indicator contains information about natural resources, reserves of minerals, raw materials, energy, fisheries and forest resources.
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Andrey Zelenin Student (140) 1 month ago
fish, oil, oyster harvesting.
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Maxim Surmin Student (197) 3 weeks ago
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