In recent decades, humanity has shown increasing interest in the World Ocean, dictated, first of all, by the continuously growing needs for various types of resources - energy, mineral, chemical and biological. On a global scale, the issue of land mineral depletion is linked to the accelerated pace of global industrial production. Obviously, humanity is facing the threshold of a raw material “hunger”, which, according to economic forecasts, will begin to manifest itself more and more acutely in capitalist countries at the end of the century. The proposals of some Western scientists to limit production to a rate corresponding to the natural increase in mineral resources are essentially utopian and absurd. Among the possibilities for solving the problem of raw materials, in particular the problem of mineral and energy resources, the most promising possibility is the exploration of the ocean and seabed.Of course, this must be approached with a sober scientific approach, taking into account the mistakes made during mining on land. Any statements of this kind, such as “The ocean is an inexhaustible source” are groundless. However, it is an undeniable fact that in our time, from the bottom of the sea, the extraction of oil, gas, ferromanganese nodules, sulfur, silt containing tin, zinc, copper, and the development of underwater and coastal placers of mineral and building materials are continuously increasing.
It can be assumed that in the near future the issue of using the resources of the World Ocean will be legally regulated.
The Black Sea basin is a very interesting object for studying the geological origin of minerals. It is located on the border of two continents - Europe and Asia, surrounded by young folded mountain ranges of the Caucasus, Pontic Mountains, Crimea and Stara Planina. The nature of the subsidence and articulation of these structures on the seabed, like the Mizy platform in the west and the Russian platform in the north, is still not well understood. These platforms make up the bulk of the shelf, which in total occupies 24% of the Black Sea bottom area. Currently, this is the most promising part of the seabed for searching for oil and gas fields.
By shelf we mean “a relatively flat and relatively shallow part of the seabed, limiting the sea edge of the continents and characterized by a similar or similar rheological structure of the land” (Leontiev). This definition suggests that on the shelf one can expect the presence of minerals similar to minerals on land. Now 96 % of marine geological research and development work in the world is carried out on the shelf.
ENERGETIC RESOURCES
The main types of fuel - coal, oil, gas - occupy an important part in the energy balance of Bulgaria. Recently, there has been great interest in the search and exploration of oil and gas at the bottom of the oceans and seas. Currently, 95 countries around the world are conducting exploration work in the sea and producing 30% of the world's oil and gas production.
The northern, northwestern and western regions of the Black Sea shelf, i.e. the continuation of the surrounding land, are especially promising. The sedimentary Meso-Cenozoic complex of the Moesian, Russian and Scythian platforms continues on the shelf, which to varying degrees contains oil and gas. Favorable conditions of the shelf compared to land are expressed in an increase in the thickness of the layers and a change in their occurrence - due to the evolution of the Black Sea depression.
To localize a gas-oil field, it is necessary to determine the following conditions: 1) structure (anticline, monocline, etc.), 2) layers with suitable reservoir properties (porosity, fracturing, voids), 3) screening layers (virtually impermeable to liquids).
If the structure - the first necessary condition - can be determined relatively accurately, then the remaining two conditions, as well as the very presence of oil and gas, can only be estimated approximately by modern geophysical methods. Therefore, the search for oil and gas deposits, especially at sea, is often associated with a certain risk, not to mention the difficulties of a purely production nature that arise.
As a result of early geophysical studies, it was established that the structure of the Black Sea shelf is more diverse and complex than the structure of the shelf. Based on the structural layers (Paleozoic, Triassic, Cretaceous, etc.), the degree of expression of the structure is determined, which is one of the main conditions for the localization of gas and oil deposits. In general, about 60 geological structures have been identified so far in the waters of the Black Sea shelf.
This optimistic assessment is based on the fact that in one of these structures (the Golitsin structure, located southeast of Odessa), in the Maikop (Oligocene) formations, gas deposits were discovered in 1969 during the first sounding of the Black Sea. Since 1976, on the Romanian shelf east of Constanta, a second marine sounding has been carried out in one of the structures identified by Jurassic-Cretaceous strata.
Relatively recently, geophysical research began on the Bulgarian shelf. The section from Cape Emine to the Bulgarian-Romanian border is promising. Currently, a number of structures have been identified from sediments, for example, the large Tyulenovskaya structure, as well as BalchyksKaya, Kranevskaya, Yuzhno-Kaliakrinskaya, etc.
In addition to structures discovered from deposits whose oil and gas potential on land has been established (limestones and dolomites of the Tyulenovskoye field and Middle Triassic dolomites of the Dolnodybniky field), Paleogene and even Neogene structures on the shelf are of particular interest due to the rapid increase in their thickness towards the open parts of the sea. According to geophysical studies, on the Romanian shelf the thickness of the Paleogene-Neogene sedimentary complex increases significantly in the same direction, which is already sufficient reason to consider it as an oil and gas formation. However, small lenses of gas in Oligocene deposits have been established near Bylgarevo, Tolbukhinsky district, and Staro-Oryahovo, Varna district. Therefore, a particularly favorable structure (complemented mainly by tertiary sediments) for searching for oil and gas on the Bulgarian shelf at the second stage will be the marine continuation of the Nizhnekamchia depression. Here you can count on the so-called gas-oil fields of a non-structural type.
Pay attention to geological structure of the Black Sea basin, the continental slope and the bottom of the basin are also considered especially promising. Based on geophysical studies of the deep-sea Black Sea basin, it has been established that one powerful sedimentary complex takes part in its structure. It is assumed that it consists of limestones, mudstone sands, dolomites, etc., i.e., rocks similar to those that make up the surrounding land. Further elucidation of the conditions of their occurrence is of undoubted interest. This, in turn, is associated with the creation of technical means for the exploration and exploitation of deposits at great depths. In 1975, the deep-sea Black Sea basin not far from the Bosphorus was probed from the American vessel Glomar Challenger. Having passed a two-kilometer layer of water, the probe traveled another 1 km in the sediments of the Black Sea bottom.
MINERAL RESOURCES
The reserves of ferromanganese nodules in the World Ocean are estimated at approximately 900 billion tons. The first ferromanganese nodules in the Black Sea were discovered by N. I. Andrusov in 1890 during expeditions on the ship Chernomorets. Later, the nodules were studied by K. O. Mila - Shevich, S. A. Zernov, A. G. Titov. The research results were summarized by N. M. Strakhov in 1968. Currently, three nodule fields are known in the Black Sea: the first - south of Cape Tarkhankut (western part of the Crimean Peninsula), the second , little studied, west of the Rioni River delta, the third - on the Turkish part of the shelf and continental slope east of Sinop.
The field of ferromanganese nodules, located near Cape Tarkhankut, is located in the upper two-meter layer of Donnkh silt-clay deposits with inclusions of Modiola faseolina. There are three layers enriched with nodules, 30-40 cm thick: superficial, Upper Dzhemetinsky and Dzhemetinsky. The diameter of the nodules rarely exceeds 1-2 cm. The dominant shape of the formations is flat, due to the shape of the shells of Modiola faseolina, around which a soot-like (from dark to gray-brown or light brown) mass, composed of manganese hydroxides and carbonates, grows. The density of ferromanganese nodules in this field is, according to N. M. Strakhov, 2.5 kg per 1 m2. The chemical composition of nodules varies within fairly wide limits.
About 30 elements were discovered in them, the most important of them: iron - 18.24^36.56%, manganese - 1.45-13.95, phosphorus -1.1, titanium - 0.095, organic carbon - 0.67% . In addition, the nodules contain 14.45% silicon dioxide, 2.13% aluminum trioxide, 4.4% calcium hydroxide, 2.44% magnesium oxide, 0.14% sodium oxide, etc.
The presence of vanadium, chromium, nickel, cobalt, copper, molybdenum, tungsten was noted, and spectral analysis revealed arsenic, barium, beryllium, scandium, lanthanum, yttrium, ytterbium.
Black Sea ferromanganese nodules have some specific features that distinguish them from oceanic nodules. They appear due to different conditions of formation.
According to N.M. Strakhov, the process of ore sedimentation occurs only with normal water exchange. This is the only way to explain the absence of ferromanganese nodules in the deep-sea part of the Black Sea, where such a regime is impossible. The thickness of the layer enriched with ore elements is only a few centimeters. Nodules are located on the surface of sediments adjacent to water. In order for a concretion to form, among other things, a natural crystallization nucleus is necessary. Such a core consists of fragments of Modiola faseolina shells and various terrigenous grains. In experiments with magnetite and other sands in the Karkinitsky Gulf and the Sea of Azov, the annual increase in nodules was calculated.
At present, ferromanganese nodules of the Black Sea bottom constitute only reserves, the intensity of exploration and use of which in the near future will depend on the needs of individual countries.
In recent years, the coast and seabed have been considered as the main mining sites for platinum, diamond, tin, titanium, and rare minerals. Now about 15% of the world's production of useful minerals from placers occurs in the coastal parts of the seas and oceans. Their ever-increasing importance in industry depends on the development and improvement of technical means of operation. Most researchers define placer deposits as deposits containing grains or crystals of useful minerals, resistant to weathering processes, which were formed under conditions of constant wave action. In most cases, such deposits appear in modern coastal terraces or on the seabed. The currently known placers in the Black Sea are located near the modern coastline. Given that the coastline was different in the Pleistocene and Holocene, there is reason to believe that placer deposits may occur on the shelf at great depths.
The concentration of heavy minerals on Black Sea beaches is significant almost everywhere. In 1945, the exploitation of the Urek magnetite sand deposit in the USSR began. Significant concentrations of heavy minerals have been found near the mouth of the Danube, on beaches from the mouth of the Danube to Cape Burnas in the northwest.
The same applies to the Dnieper-Bug estuary and the beaches of the Crimean peninsula.
On the Bulgarian Black Sea coast, the titanium-magnetite sands of the Burgas Bay are of significant interest. In addition to titanium and magnetite, rutile, ilmenite and other minerals are also found here. Detailed geological and geophysical studies conducted since 1973 revealed an increased concentration of ore minerals at a depth of 20-30 m, and areas were noted where the sands contain approximately 3% magnetite. One area is located between Nessebar and Pomorie (the mouth of the Aheloy River), the other is near Sarafovo. The increased concentration of ore in the first region is explained by the erosion and transport activity of the Aheloy River, in the second - by the abrasive activity of the sea in the area of the Sarafov landslides, the initial content of magnetite in which is approximately 2%.
On the beaches of the northwestern part of the Black Sea, individual diamonds measuring 0.14-0.35 mm - colorless, yellow, gray - were found. Diamonds in the considered coastal zone of the Black Sea were found in sedimentary rocks (Devonian, Permian, Cretaceous, Neogene). Small pieces of gold were found in the northwestern part of the Black Sea and in the mouth of the Danube.
The coastal zone, where deposits of valuable minerals are discovered, is a distribution zone for building materials. First of all, these are a variety of sands. Currently, in England alone, about 150 million tons of high-quality sands are mined for construction and other needs, in the USA - about 60 million tons of sand and 80 million tons of small pebbles. In the area of the Gulf of Mexico and San Francisco Bay, carbonate shell rock, used in the production of magnesium, is mined from the seabed.
The distribution and reserves of various building materials on the Black Sea shelf have not been sufficiently studied. Tourist and resort areas should not be included in mining zones; on the contrary, it is important to take measures in them to prevent phenomena that could disrupt the natural balance - landslides, abrasion, etc.
A huge deposit of construction sands was discovered on the Odessa Bank. The mineral composition of sands is very diverse. According to E.N. Nevessky, the sandbank formed in the Neo-Euxinian time as a complex of swamp and alluvial formations. Sands are also being mined in the Yalta Bay.
In the period 1968-1970. Sand dredging was carried out in the Burgas Bay, but was subsequently suspended. It must be emphasized that the coastal zone reacts very subtly to changes in some factors that determine its equilibrium. When some sand is removed, abrasion may increase, which may result in the beach shrinking or disappearing.
Aleurite soils, which are found at depths of 20–70 m in virtually inexhaustible reserves, will perhaps in the near future be of significant interest as a source raw material for the production of fire-resistant materials.
About one third of Turkey's coal reserves are located under water, which are in the process of exploitation. The sea boundary of this deposit has not yet been established.
Underwater deposits of iron ore are known in almost all marine areas. The so-called Cimmerian iron ores were discovered on the Soviet coast.
Christian Humanities and Economics Open University
Faculty of Humanities and Economics
Humanities Department
ABSTRACT
P O K U R S U:
« Use and protection of Black Sea resources"
1st year student
Distance learning in the humanities
Departments of the Faculty of Humanities
Supervisor- …
Odessa-2010
Introduction
Plant and animal resources of the Black Sea.
Energy and mineral resources.
Protection of Black Sea resources
International programs for the protection of the Black Sea
Bibliography.
Introduction.
Since ancient times, the population living on the shores of the Black Sea has been looking for opportunities to use its food resources. The main attention was paid to the fish fauna, and then mainly to the abundant fish species in the coastal zone. Fishing in the Black Sea has retained its importance to this day. At the same time, other biological resources - commercial invertebrates and algae - are increasingly used in the food industry and pharmacology.
^ 1. Plant and animal resources of the Black Sea .
In terms of biomass and productivity, algae ranks first among the plant resources of the Black Sea. Macrophytes occupy the shallow water zone to a depth of 60-80 m, but most of them are found (excluding the Zernov phyllophoran field) on rocky and rocky soils to a depth of 10 m. The biomass of macrophytes in the Black Sea is estimated at 10 million tons. Of the large number of algae species growing in the Black Sea, only a few species are currently used. In first place in terms of use is the red algae phyllophora, the reserves of which in the northwestern part of the Black Sea are estimated at 5-7 million tons. The maximum biomass of this algae per 1 m2 reaches 5.9 kg. Along the Bulgarian coast, phyllophora is rare and in very small quantities. Its accumulations in the Zernov field are used for industrial purposes. Ukraine has special vessels that collect phyllophora in this sea zone. From dried and washed with hot water raw materials, agar-agar is obtained, the mass of which is 20-22% of the mass of dry phyllophora. Agar-agar is used as a gelling agent in industry. If you add it to bread, the latter does not go stale for a long time. Agar-agar is also used in the textile industry - it gives fabrics density, shine and softness. Agar-agar is also used in the production of certain medicines and in the preparation of cosmetic creams. [Stepanov V.N. The Black Sea: resources and problems. - Leningrad, Gidrometeoizdat, 1981. - pp. 33-34].
Of interest are the thickets of brown algae Cystoseira, common on the rocky bottom near the seashore. Research by V. Petrova (1975) showed that the total reserves of Cystoseira in the sublittoral zone off the Bulgarian coast reach 330 thousand tons. In the zone with depths of up to 2 m, annual production of 10 thousand tons of raw material is possible. Algin is extracted from cystoseira, which is used in the food industry and for the production of various technical emulsions. Both in Bulgaria and in other Black Sea countries, the issue of mechanized production of cystoseira has not been resolved. In some areas of the coast, algae (mainly cystoseira) periodically thrown out by the sea are collected and used as an additive to nutritional mixtures for farm animals.
Of the flowering plants in the Black Sea, sea grass (Zostera) is relatively widespread. It grows at depths of up to 6 m and is rarely found at depths of up to 15 m. Zostera reserves in the Black Sea reach 1 million tons. Small fields of sea grass are also found off the Bulgarian coast. Zostera is used mainly as packaging and stuffing material in the furniture industry. [Nature of the Odessa region: resources, their rational use and protection. - Kyiv-Odessa, Vishcha School, 1979.- P.59-60].
The animal resources of the Black Sea are of very important economic importance. These include some invertebrate animals and a number of commercially valuable fish.
The first place among non-fish raw materials should be the mussel. Its reserves are approximately 9.5 million tons (Moi-seev). According to research by V. Abadzhieva and T. Marinov (1967), in the Bulgarian part of the sea, mussel stocks exceed 300 thousand tons, of which about 100 thousand tons can be considered as a commercial stock. However, recently the predatory rapana snail has caused significant damage to the mussel fields. Mussel meat contains the same amount of proteins as the meat of farm animals and fish, but it is richer in some amino acids (methionine, tyrosine, tryptophan), microelements and vitamins. In terms of taste, it is most suitable for preparing savory dishes; it is used as food in fresh, canned and dried form. Industrial production of mussels in Bulgaria is carried out using special dredges. Among other mollusks, the heart is used as food, and among crustaceans, shrimp. But their quantity and distribution do not allow industrial fishing. [Russ T.S. Fish resources of the Black Sea and their changes: [Text] // Black Sea Ecological Bulletin. - 2006. - No. 3-4 (21-22) veresen-gruden.- p.256].
In coastal areas and partly in Lake Varna, oysters are found, which were previously the object of fishing. In some coastal areas, stone crab is used as food. Currently, oysters and stone crab have no commercial value. A small number of crayfish are caught in the Blatnitsky and Shablensky lakes, as well as in the Mandrensky reservoir.
The biomass of fish in the Black Sea was estimated differently in different periods. After hydrogen sulfide was discovered in the deep waters of the basin, it was believed that the overall biological productivity of the sea was low. Before and after the Second World War, this estimate, which included an estimate of fish biomass, was significantly overestimated, but it was not confirmed by fish catches. When new methods for determining the production of organic matter began to be used, a modern understanding of the biomass and annual production of organisms in the Black Sea was obtained. According to the definitions of P. A. Moiseev, fish biomass should not be estimated at more than 1 million tons. He considers their more realistic biomass to be 500-600 thousand tons, which is only 0.8% of the gross biomass of all organisms. [Black Sea: collection / translation from Bulgarian. - Leningrad: "Gidrometeoizdat", 1983. - pp. 344-351].
Anchovy, sprat and horse mackerel are of decisive importance in the industrial fishery of the Black Sea. In certain periods, this group of commercial fish also includes bonito and mackerel. The second most important group of fish includes Kalkan, Black Sea trout, bluefish, mullet, etc. The main factor determining the volume of catches is the state of stocks of the main fish species. They also depend on many reasons, the main of which are abiotic factors that cause sudden changes in the amount of plankton. The amount of plankton, in turn, affects the number of planktivorous fish and subsequent trophic levels of the food chain. Fishing catches are also influenced to a large extent by the behavior and distribution of the main species.
Commercial fish living in the Black Sea are divided into two groups according to their biological characteristics and the nature of changes in stocks.
The first group includes fish with a long life cycle, i.e. fish that reach sexual maturity late. This group is dominated by species that reproduce more than once. Fish populations of the first group do not have high numbers, and their stocks change little. These are sturgeon fish and kalkan.
The second group includes species that have a short life cycle and puberty occurs early - sprat, anchovy, etc. In their populations, the young generation predominates over mature individuals. As a result, in one harvest year, stocks of sprat and anchovy can increase many times over. Losses - due to natural death, from predators and fishing - are compensated when the recruitment of juveniles is significant. Otherwise, stocks of the species begin to decrease.
Thus, after 1968, mackerel stocks decreased so much that it lost its commercial importance. The decrease in its numbers coincided with a relative increase in the stocks of predatory species - bluefish and partly bonito. The reduction of the parent school was so severe that the remaining individuals were not able to quickly increase the reproduction of the species. This was facilitated by the small breeding area of mackerel (only part of the Sea of Marmara) and the coincidence of the wintering area of mackerel with the wintering area of some predatory species (also the Sea of Marmara). Industrial fishing in the Black Sea waters is carried out all year round, but depending on the migration and distribution of the main species, some areas become more important in certain seasons. For example, anchovy along the Anatolian and Caucasian coasts is caught mainly in winter.
In the Bosphorus region, fish catches increase in the spring, when migrating species (horse mackerel, bonito, mackerel) from the strait and the Sea of Marmara enter the Black Sea. The same area becomes lively in the second half of autumn, when these species return to their wintering grounds. In the northwestern part of the Black Sea and areas near the Crimean Peninsula, commercially important species reproduce and remain for a long period of time. As a result, fishing in these waters intensifies in May - October. The fishing fleet is concentrated near the Kerch Strait, when the Azov anchovy migrates to wintering areas, to the Caucasian coast. The bulk of the catch of all Black Sea countries, except Romania, is obtained from ships. In coastal areas they are caught with fixed seines, nets and other fishing equipment.
^ 2. Energy and mineral resources of the Black Sea
According to existing classifications, energy resources mean reserves of oil, gas, coal, and mineral resources mean reserves of metals and minerals.
In recent decades, humanity has shown increasing interest in the World Ocean, dictated, first of all, by the continuously growing needs for various types of resources - energy, mineral, chemical and biological. On a global scale, the issue of depletion of land minerals is associated with the accelerated pace of world industrial production. Obviously, humanity is facing the threshold of a raw material “hunger,” which, according to economic forecasts, will begin to manifest itself more and more acutely in capitalist countries at the end of the century.
The proposals of some Western scientists to limit production to a rate corresponding to the natural increase in mineral resources are essentially utopian and absurd. Among the possibilities for solving the problem of raw materials, in particular the problem of mineral and energy resources, the most promising opportunity is the study of the ocean and seabed. Of course, it is necessary to approach this soberly and scientifically, taking into account the mistakes made during mining on land. Any statements such as “the ocean is an inexhaustible source” are groundless. However, the undeniable fact is that in our time, from the bottom of the sea, the production of oil, gas, iron-manganese nodules, sulfur, silt containing tin, is continuously increasing, zinc, copper, development of underwater and coastal mineral deposits and construction materials. [Zaitsev Yu. Your friend the sea: essay. - O.: Mayak, 1985. - p.27].
The Black Sea basin is a very interesting object for studying the geological origin of minerals. It is located on the border of two continents - Europe and Asia, surrounded by young folded mountain ranges of the Caucasus, Pontic Mountains, Crimea and Stara Planina. The nature of the subsidence and articulation of these structures on the seabed, like the Mysian platform in the west and the Russian platform in the north, is still not well understood. These platforms make up the bulk of the shelf, which in total occupies 24% of the Black Sea bottom area. Currently, this is the most promising part of the seabed for searching for oil and gas fields.
By shelf we mean a relatively flat and relatively shallow part of the seabed, limiting the sea edge of the continents and characterized by a similar or similar rheological structure of the land. This definition suggests that the shelf can be expected to contain minerals similar to those found on land. Now 96% of marine geological research and exploitation work in the world is carried out on the shelf.
^ Energetic resources
The main types of fuel - coal, oil, gas - occupy an important part in the energy balance of Ukraine. Recently, there has been great interest in the search and exploration of oil and gas at the bottom of the Black Sea. The northern, northwestern and western regions of the Black Sea shelf, i.e., an extension of the surrounding land, are especially promising. The sedimentary Meso-Cenozoic complex of the Moesian, Russian and Scythian platforms continues on the shelf, which to one degree or another contains oil and gas. Favorable conditions of the shelf compared to land are expressed in an increase in the thickness of the layers and a change in their occurrence in connection with the evolution of the Black Sea depression.
To localize a gas-oil field, it is necessary to determine the following conditions: 1) structure (anti-cline, monocline, etc.), 2) layers with suitable reservoir properties (porosity, fracturing, voids) 3) screening layers (virtually impermeable to liquids).
If the structure - the first necessary condition - can be determined relatively accurately, then the remaining two conditions, as well as the very presence of oil and gas, can be assessed only approximately by modern geophysical methods. Therefore, the search for oil and gas deposits, especially at sea, is often associated with a certain risk, not to mention the difficulties that arise from a purely production nature.
In the Golitsyn structure, located southeast of Odessa, in the Maikop (Oligocene) layers, gas deposits were discovered.
According to geophysical studies, the Romanian shelf should also be considered as an oil and gas formation.
Taking into account the geological structure of the Black Sea basin, the continental slope and bottom of the basin are also considered particularly promising. Based on geophysical studies of the deep-water Black Sea basin, it was established that one powerful sedimentary complex takes part in its structure. It is assumed that it consists of limestones, argillic sands, dolomites, etc., i.e., rocks similar to those that make up the surrounding land.
Further clarification of the conditions of their occurrence is of undoubted interest. This, in turn, is associated with the creation of technical means for the exploration and exploitation of deposits at great depths. In 1975, the deep-sea Black Sea basin near the Bosphorus was sounded from the American vessel Glomar Challenger. Having passed through a two-kilometer layer of water, the probe traveled another 1 km in the sediments of the black seabed.
^ Mineral resources
The reserves of ferromanganese nodules in the World Ocean are estimated at approximately 900 billion tons. The first ferromanganese nodules in the Black Sea were discovered by N. I. Andrusov in 1890 during an expedition on the ship Chernomorets. Later, the nodules were studied by K. O. Milashevich, S. A. Zernov, A. G. Titov. Results research was summarized by N.M. Strakhov in 1968. Currently, three nodule fields are known in the Black Sea: the first - south of Cape Tarkhankut (western part of the Crimean Peninsula), the second, little studied, - west of the Rioni River delta, the third - on the Turkish part of the shelf and continental slope east of Sinop.
At present, ferromanganese nodules of the Black Sea bottom constitute only reserves, the intensity of research and use of which in the near future will depend on the needs of individual countries.
In recent years, the coast and seabed have been considered as the main mining sites for platinum, diamond, tin, titanium, and rare minerals. Currently, about 15% of the world's production of useful minerals from placers occurs in the coastal parts of the seas and oceans. Their ever-increasing importance in industry depends on the development and improvement of technical means of operation. Most researchers define placer deposits as deposits containing grains or crystals of useful minerals, resistant to weathering processes, which were formed under conditions of constant wave action. In most cases, such deposits appear in modern coastal terraces or on the seabed. The currently known placers in the Black Sea are located near the modern coastline. Considering that the coastline was different in the Pleistocene and Holocene, there is reason to assume that placer deposits can be found on the shelf at great depths.
The concentration of heavy minerals on Black Sea beaches is significant almost everywhere. In 1945, the exploitation of the Urek magnetite sand deposit began. Significant concentrations of heavy minerals have been found near the mouth of the Danube, on beaches from the mouth of the Danube to Cape Burnas in the northwest. The same applies to the Dnieper-Bug estuary and the beaches of the Crimean peninsula. On the Bulgarian Black Sea coast, the titanium-magnetite sands of the Burgas Bay are of significant interest. In addition to titanium and magnetite, rutile, ilmenite and other minerals are also found here. Detailed geological and geophysical studies conducted since 1973 revealed an increased concentration of ore minerals at a depth of 20-30 m, and areas were noted where the sands contain approximately 3% magnetite. One area is located between Nessebar and Pomorie (the mouth of the Aheloy River), the other is near Sarafovo. The increased concentration of ore in the first area is explained by erosion and the transport activity of the Aheloy River, in the second - by the abrasion activity of the sea in the area of the Sarafovo landslides, the original The magnetite content in which is approximately 2%.
On the beaches of the northwestern part of the Black Sea, individual diamonds measuring 0.14-0.35 mm - colorless, yellow, gray - were found. Diamonds in the considered coastal zone of the Black Sea were found in sedimentary rocks (Devonian, Permian, Cretaceous, Neogene). Small pieces of gold were found in the northwestern part of the Black Sea and near the mouth of the Danube.
The coastal zone, where deposits of valuable minerals have been discovered, is also a distribution zone for building materials. First of all, these are a variety of sands. The distribution and reserves of various construction materials on the Black Sea shelf have not been sufficiently studied. Tourist and resort areas should not be included in mining zones; on the contrary, it is important to take measures in them to prevent phenomena that could disrupt the natural balance - landslides, abrasion, etc.
A huge deposit of construction sands was discovered on the Odessa Bank. The mineral composition of sands is very diverse. According to E.N. Nevessky, the sand bank was formed in the Neo-Euxinian time as a complex of swamp and alluvial formations. Sands are also being mined in the Yalta Bay.
In the period 1968-1970. Sand dredging was carried out in the Burgas Bay, but was subsequently suspended. It must be emphasized that the coastal zone reacts very subtly to changes in some factors that determine its balance. When a certain amount of sand is removed, abrasion may increase, as a result of which the beach is likely to shrink or disappear.
Perhaps in the near future, silty soils, found at depths of 20-70 m in almost inexhaustible reserves, will be of significant interest as a source raw material for the production of fire-resistant materials.
About one third of Turkey's coal reserves, which are in operation, are located under water. The marine boundary of this field has not yet been established.
Underwater iron ore deposits are known in almost all marine areas. The so-called Cimmerian iron ores have been discovered on the Ukrainian coast.
^ Protection of Black Sea resources
The Ukrainian Scientific Center for Marine Ecology (UkrNCEM), being the parent organization of the Ministry of Ecology of Ukraine for marine environmental management and the International Active Center for Monitoring and Assessment of Environmental Conditions, conducts comprehensive monitoring studies of the Black and Azov Seas. [Fesyunov O.E. Geoecology of the northwestern shelf of the Black Sea. - O.: Astroprint, 2000. - p.25].
To save the Black Sea ecosystem, the Convention for the Protection and Conservation of the Black Sea was signed in 1992 in Bucharest (Romania), which Ukraine ratified in 1994. To develop the provisions of the Convention, a meeting of the ministers of ecology of six countries was held in Odessa in 1993 and the Odessa Declaration was signed. To implement the Odessa Declaration, the World Environmental Fund organized an international program to study environmental problems of the Black Sea.
As a result of 6 years of joint work of all the Black Sea countries, the main priorities and primary tasks for the rehabilitation of the Black Sea ecosystem were identified. In each country, “hot spots” have been identified, which account for up to 85% of all pollution in the Black Sea.
“Hot spots” of Ukraine: 3 spots are in the region of Odessa and Ilyichevsk - these are imperfect treatment facilities; 5 points are in the Crimea region - this is the lack of modern treatment facilities in Ba-laklava, Evpatoria, Yalta, Gurzuf, Sevastopol; 1 point - to the Kerch region - the environmentally hazardous Kamyshburunsky plant; 1 point - to the Krasnoperekopsk region - the environmentally hazardous Krasnoperekopsk bromine plant. It is the reconstruction of the above-mentioned structures that will give tangible results in the improvement of the Black Sea ecosystem.
In 1995, based on research on the International Black Sea Program, a Strategic Action Plan was prepared and signed by the ministers of ecology of 6 countries, on the basis of which each country had to prepare a national action plan to improve the environmental situation.
As part of the implementation of the Strategic Action Plan of Ukraine, a “Concept for the protection and creation of the abundant natural environment of the Azov and Black Seas” has been prepared. The UkrNCEM has prepared and agreed with all countries a Strategy for regional environmental monitoring of the Black Sea for all Black Sea countries, based on the capabilities of each country (availability of swimming facilities, analytical equipment, etc.). Also, the UkrSCEM has developed a document on quality standards for marine environmental research, which has been agreed upon with all Black Sea countries and accepted for implementation. In 2001, the document “Regional Database and Information Development Strategy” was prepared. This document defines the basic principles of data exchange that the countries of the Black Sea region receive as a result of monitoring observations of the state of the Black Sea, and formats for data exchange are developed. These documents made it possible to assess the current state of the Black Sea ecosystem in recent years.
At the end of 1999, the State Program of Ukraine for the protection and restoration of the Black and Azov Seas was prepared and agreed with the Cabinet of Ministers. In 2001, for the meeting of ministers of the countries of the Black Sea region, UkrNCEM prepared a National report “Black Sea Dovkilla State for 1996-2000”, which assessed the state of the Black Sea and developed specific measures that should be taken by the Government of Ukraine in the coming years to fulfill the tasks , defined by the Strategic Action Plan.
Analysis of the existing legal framework and research conducted within the framework of international programs show that priorities for the revival of the Black Sea ecosystem have changed significantly. Data from UkrNTsEM fully confirm this. Moreover, for a more clear analysis of the ecological state of the Black Sea, it is necessary to conditionally divide the water areas into several levels, in which there are different mechanisms for the entry of pollutants into the ecosystem, and ways of removing them from it.
The recreational zone experiences the greatest anthropogenic influence. This happens for many reasons. In recent years, about 7.4 million m3 of wastewater has been discharged into the Black Sea (in the recreation zone within Ukraine), practically without treatment, about 195 million m3 of insufficiently treated wastewater. The recreational zone receives annually about 31 million tons of suspended substances, etc. It is appropriate to note that these figures do not reflect the volume of discharges, since recently the construction of sanatoriums, campsites, public places and other facilities in the recreational area has been carried out haphazardly, in violation of the legislation of Ukraine. The situation is further aggravated due to the adoption of the law on land privatization, while there is still no regulatory framework for the use of the recreational zone of the Azov and Black Seas. The current state of the Black Sea recreational zone is characterized by significant pollution of water, bottom sediments and beach sand. Organochlorine pesticides (DDT, HCH), polychlorinated biphenyls (PCBs), synthetic surfactants (surfactants), petroleum hydrocarbons (PH), polyaromatic hydrocarbons (PAHs), the most toxic part of oil, which has carcinogenic properties, primarily 3,4-benzapyrene, phenols, dissolved organic matter, and some heavy metals in varying quantities are almost constant components of coastal waters and bottom sediments.
In recent years, the amount of petroleum products in the water of the recreational zone of the Odessa region has stabilized. However, the Black Sea is becoming a transport corridor for oil transportation and the construction of oil terminals in all six Black Sea countries can lead to significant pollution of the water area with petroleum hydrocarbons.
Synthetic surfactants (detergents) in the recreational area are always present in quantities exceeding the maximum permissible. Moreover, recently a huge amount of foreign-made detergents have appeared, the physico-chemical properties, effects and decay period of which are unknown. It is this circumstance that suggests the emergence of unknown allergic skin diseases in humans.
Traces of heavy metals are found almost everywhere in the recreational area of the Black Sea. Concentrations of arsenic, chromium, lithium, strontium, and mercury in some cases exceed the maximum permissible standards. The remaining metals are below the maximum permissible standards, but are 10 times higher than their natural content in the marine environment. They are significantly concentrated in bottom sediments.
The water of the recreational zone contains large quantities of dissolved organic substances. Significant concentrations of phosphorus and nitrogen in the recreational zone ultimately lead to a decrease in oxygen dissolved in water to values at which extensive zones of death phenomena and the appearance of hydrogen sulfide are observed. Thus, the recreational zone of the northwestern part of the Black Sea within the Odessa region is in a state of crisis, despite the fact that many enterprises that are potential polluters are not operating at full capacity.
In practice, the average concentrations of the main pollutants in the recreational zone do not differ significantly from pollution in the shelf zone and in the Gulf of Odessa. The shelf zone is contaminated with petroleum products in concentrations that in some cases exceed the maximum permissible limits. Significant concentrations of dissolved petroleum products are found in bottom sediments. The average concentrations of polyaromatic hydrocarbons decrease slightly. Heavy metals are found in trace amounts in the waters of the Black Sea shelf zone. Significant concentrations of organic matter and biogenic elements phosphorus and nitrogen are found everywhere in all areas of the shelf zone. [Mikhailov V.I., Gavrilova T.A., Lisovsky R.I., Issues of rational use of the resources of the Black Sea: [Text] //Ecology and marriage: a collection of scientific works. Issue 1.- O.: ODNB, 2002.- p.47-51].
In all areas of the Odessa Bay, there is a layer of silt at the bottom, which in some cases exceeds 3 cm; this phenomenon has been observed in the last 10 years. The silt practically destroys all living things living at the bottom in our region.
The analysis convincingly proves the degradation of the Black Sea ecosystem, despite the decrease in industrial discharges, since the amount of household wastewater and organic matter is constantly increasing, causing irreparable harm to the ecosystem.
Unfortunately, in the sphere of environmental management in the Black Sea in the past there was no separate array of environmental and economic requirements, standards, regulations regulating economic activities in marine areas, international rivers and ensuring the rational use of natural marine and river spaces, taking into account the requirements of protection natural environment. An example of this is the gross violations on the part of Romania during discharges into the Danube River and the lack of legal norms regarding Romania’s responsibility for these actions.
^ International programs for the protection of the Black Sea
According to these documents, the main strategic goal of Ukraine in protecting the natural environment is: ensuring the environmental safety of present and future generations; renewal and preservation of the biosphere; rational and integrated use of the entire natural resource potential of Ukraine, including the Black Sea basin; consistent solution to the problems of economic development of Ukraine along the path of achieving full biosphere compatibility.
In this regard, the Ukrainian government is tasked with environmental tasks related to stopping pollution of the Black and Azov Seas and improving their ecological condition.
At the present stage of socio-economic development, the conditions and prerequisites for specifying the state’s environmental policy, expanding the application of economic methods and environmental and economic standards in regulating marine environmental management are already being formed. This predetermines the need to form a qualitatively new environmental, economic and legal regulatory framework for marine environmental management and solve the problems of preventing the environmental and economic crisis in the basins of the Black and Azov Seas.
In April 1992, in Bucharest, all representatives of the Black Sea states signed the “Convention for the Protection of the Black Sea from Pollution.” To achieve the goals of the Convention, the parties to the agreement approved the Commission for the Protection of the Black Sea with a secretariat including representatives of all Black Sea states. The Convention sets out the main actions of the parties aimed at protecting the marine environment of the Black Sea. The main ones are: preventing the discharge of harmful substances from any source; reduction of pollution from coastal sources; prevention of pollution from ships; cooperation in combating pollution in emergency situations; reduction and control of waste disposal; protection of biological resources; monitoring the state of the marine environment.
In furtherance of the provisions of the Convention, in April 1993 in Odessa, all ministers of environmental protection of the Black Sea countries signed the “Ministerial Declaration on the Protection of the Black Sea”. The next stage of Ukraine’s participation in international treaties on the protection of the Black Sea was participation in the creation of the “Strategic Action Plan for the Improvement and Protection of the Black Sea,” which was signed in Istanbul in October 1996. Ukraine, together with the Black Sea countries, took upon itself the obligation to implement international agreements in the following areas: reducing levels of seawater pollution from coastal sources; reducing emissions of pollutants into the atmosphere of coastal zones; control and reduction of discharges from point sources; reducing pollution from ships; creation of a unified Black Sea plan for eliminating the consequences of accidents; control over the movement of waste; assessment and monitoring of the state of the marine environment; protection of biological diversity and landscapes; assessment of the impact of human activities on the natural environment; Coastal zone management. [Patlatyuk E.G., International programs for the protection of the Black Sea and Ukraine’s participation in them: [Text] //Ecology and marriage: a collection of scientific works. Issue 1.- O.: ODNB, 2002.- p.62-63].
The “Strategic Plan” provides for financing the planned work, mainly from the Black Sea Environmental Fund being created, as well as from revenues from the states parties to the Bucharest Convention. To implement the plan, Active Centers were created in the Convention states in the main areas: Center for Ecology and Safety of Shipping (Bulgaria, Varna); Center for Monitoring and Assessment of Marine Pollution (Ukraine, Odessa, UkrNTsEM); Center for Coastal Zone Management Methodology (Russia, Krasnodar); Center for Biological Diversity (Georgia, Batumi); Center for Fisheries and Living Marine Resources (Romania, Constanta). To coordinate the work on the Strategic Plan, the Secretariat of the Commission was created, currently located in Istanbul.
In terms of the development of Ukraine’s international obligations, on March 22, 2001, the President of Ukraine signed the Law of Ukraine “On approval of the national program for the protection and restoration of the environment of the Azov and Black Seas,” which provides for a set of national measures aimed at improving the ecological state of the seas with specific the timing of implementation and financing of this environmental program.
Conclusion.
There cannot be a single solution to the issue of all types of waste and where they are dumped. However, there is a need to develop more rational frameworks for making decisions about how to process and dispose of waste. No oceanographer wants hazardous waste to accumulate where he works or to have hazardous waste accumulate on land where he lives. However, since waste must find a place anyway, it would be preferable to make a choice based on knowledge of all factors.
The protection of nature, and water resources in particular, is a task of the 21st century, a problem that has become social. To fundamentally improve the situation, targeted and thoughtful actions will be needed. A responsible and effective policy in relation to the water environment will be possible only if we accumulate reliable data on the current state of the environment, reasonable knowledge about the interaction of important environmental factors, and if we develop new methods for reducing and preventing harm caused to Nature by Man.
Bibliography:
1. Zaitsev Yu. Your friend the sea: an essay. - O.: Mayak, 1985.
2. Krivosheeva O.M. Plant of fishery resources in the Black Sea basin, their protection and regulation of industry: [Text] // Black Sea Environmental Bulletin.- 2009.- No. 4 (34) breast.- p.197-198.
3. Mikhailov V.I., Gavrilova T.A., Lisovsky R.I., Issues of rational use of the resources of the Black Sea: [Text] //Ecology and marriage: a collection of scientific works. Issue 1.- O.: ODNB, 2002.
4. Patlatyuk E.G., International programs for the protection of the Black Sea and Ukraine’s participation in them: [Text] //Ecology and marriage: a collection of scientific works. Issue 1.- O.: ODNB, 2002.
5. Nature of the Odessa region: resources, their rational use and protection. - Kyiv-Odessa: Vishcha School, 1979.
6. Russ T.S. Fish resources of the Black Sea and their changes: [Text] // Black Sea Ecological Bulletin. - 2006. - No. 3-4 (21-22) veresen-gruden.- p.256.
7. Stepanov V.N. Black Sea: resources and problems. - Leningrad, Gidrometeoizdat, 1981.
8. Fesyunov O.E. Geoecology of the northwestern shelf of the Black Sea. - O.: Astroprint, 2000.
9. Black Sea: collection / Translation from Bulgarian. - Leningrad: “Gidrometeoizdat”, 1983.
Do you know what the Black Sea is? Most people will say: “Yes, of course!” After reading this article, you will understand that you were previously familiar with the Black Sea very superficially.
The current appearance of the Black Sea has evolved over the last millennium. Surprisingly, this sea has the lowest salt content in the entire globe. Thanks to this, it has a very gentle effect on our skin.
The Black Sea is the northernmost subtropics. On its coasts you can admire palm trees, eucalyptus trees, magnolias, meadow grasses and many other representatives of the plant world. The connection between the Black Sea and the Mediterranean is responsible for the diverse fauna. The Black Sea, of course, is not so rich in representatives of the animal world, nevertheless, it is quite interesting for research. Now about everything in more detail.
Vegetable world
Today, the fauna of the sea includes 270 species of algae: green, brown, red bottom (cystoseira, phyllophora, zoster, cladophora, ulva, etc.). Phytoplankton is very diverse - about 600 species. Among them are dinoflagellates, diatoms and others.
Animal world
Compared to the Mediterranean Sea, the Black Sea has a much poorer fauna. The Black Sea has become a haven for 2.5 thousand species of animals. Among them are 500 unicellular organisms, 500 crustaceans, 200 molluscs, and 160 vertebrates. Everything else is various invertebrates. The fauna of the Mediterranean Sea, for comparison, is represented by 9 thousand species.
The Black Sea is characterized by a wide range of water salinity, moderately cold water and the presence of hydrogen sulfide at great depths. All this is due to the relatively poor fauna. The Black Sea is suitable for habitat of unpretentious species that do not require great depths at all stages of their development.
At the bottom of the sea live oysters, mussels, pecten and a predatory mollusk - rapana, which was brought by Far Eastern ships. Crabs and shrimp can be found among the stones and crevices of the coastal cliffs. The Black Sea chordate fauna is quite poor, but it is quite sufficient for divers and researchers. There are also several species of jellyfish (mainly Corneros and Aurelia), sponges and sea anemones.
The following types of fish are found in the Black Sea:
- goby (goby, whip, round, martovik, rotan),
- anchovy (Azov and Black Sea),
- dogfish shark,
- five types of mullet,
- flounder glossa,
- hake (hake),
- bluefish,
- mullet,
- sea ruff,
- mackerel,
- horse mackerel,
- haddock,
- herring,
- sprat and others.
There are also sturgeon species: beluga, sturgeon (Azov and Black Sea). The fauna of the Black Sea is not so poor - there are quite a lot of fish here.
There are also dangerous species of fish: sea dragon (the most dangerous - the spines of the gill covers and dorsal fin are poisonous), scorpionfish, stingray, which has poisonous spines on its tail.
Birds and mammals
So, the inhabitants of the Black Sea, who are they? Let's talk a little about the small representatives of the fauna. Birds include: gulls, petrels, diving ducks and cormorants. Mammals are represented by: dolphins (white-sided and bottlenose dolphins), porpoise (also called the Azov dolphin) and white-bellied seal.
Rapana - a guest from the Far East
Some inhabitants of the Black Sea did not originally live in it. Most of them came here through the Bosporus and Dardanelles straits. The reason for this was the current or their personal curiosity.
The predatory mollusk rapana entered the Black Sea in 1947. To date, he has eaten almost the entire population of oysters and scallops. Young rapana, having found a victim, drill into its shell and drink the contents. Adults hunt a little differently - they secrete mucus, which paralyzes the valves of the prey and allows the predator to eat the mollusk without any problems. Rapana itself is not threatened by anything, because due to the low salinity of the water in the sea there are no its main enemies - starfish.
Rapana is edible. It tastes like sturgeon. It is generally accepted that rapana is the closest relative of the endangered mollusks, from whose shells the Phoenicians made purple dye.
Katran shark
The marine fauna of the Black Sea is not very diverse, but quite interesting. There is even one species of shark found there. This is a spiny shark, or, as it is also called, katran. It rarely grows more than a meter in length and tries to stay deep, where the water is colder and there are no people. Among fishermen, the katran is considered a real trophy. The fact is that shark liver oil has medicinal properties. At the same time, the shark can be dangerous to humans, since its dorsal fins have spines with poison.
Jellyfish
Most often, two types of jellyfish are found in the sea: Aurelia and Cornerot. Cornerot is the largest jellyfish of the Black Sea, while Aurelia, on the contrary, is the smallest. Aurelia, as a rule, does not grow more than 30 centimeters in diameter. But the root can reach 50 cm.
Aurelia is not poisonous, and in case of contact with a person, the root can cause a burn similar to a nettle burn. It causes mild redness, burning, and in rare cases even blisters. The cornet has a bluish color with a purple dome. If you see this jellyfish in the water, just grab it by the dome and move it away from you. The dome, unlike the tentacles, is not poisonous.
Some vacationers on the beaches of the Black Sea deliberately look for encounters with poisonous jellyfish. They believe that the venom of the cornet has healing properties. There are rumors that by rubbing your body with jellyfish, you can cure yourself of sciatica. This is a misconception that has neither scientific nor practical justification. Such therapy will not bring any relief, and will cause suffering to both the patient and the jellyfish.
Glowing Sea
Among the plankton living in the waters of the Black Sea, there is one unusual species - noctiluca, also known as the night light. This is a predator algae whose diet consists of ready-made organic substances. But the main feature of Noctiluca is its ability to phosphorescent. Thanks to this algae, in August the Black Sea may seem to glow.
Sea of dead depths
Having become acquainted with the inhabitants of everyone’s favorite sea, let’s consider a couple of interesting facts. The Black Sea is by far the largest anoxic body of water in the world. Life in its waters is impossible at a depth of more than 200 meters due to the high concentration of hydrogen sulfide there. Over the years, the sea has accumulated more than a billion tons of hydrogen sulfide, which is a product of bacterial activity. There is a version that during the emergence of the Black Sea (7200 years ago), the freshwater inhabitants of the Black Sea lake, which was here earlier, died in it. Because of them, reserves of methane and hydrogen sulfide have accumulated at the bottom. But these are just guesses that have not yet been confirmed. But the fact is that due to the high content of hydrogen sulfide in the sea, the fauna is so poor.
The Black Sea, in addition, has a high content of fresh water, which also negatively affects some of its inhabitants. The fact is that the water coming from the rivers does not have time to completely evaporate. And salt water enters the sea mainly from the Bosphorus Strait, which is not enough to maintain the salt balance.
There are many hypotheses regarding the origin of the name of the Black Sea. But one of them looks the most plausible. Retrieving anchors from the waters of the Black Sea, the sailors were surprised at their color - the anchors turned black. This was due to the reaction of the metal and hydrogen sulfide. Perhaps this is why the sea received the name that we know now. By the way, one of the first names sounded like “sea of dead depths.” Now we know what causes this.
Underwater river
Surprisingly, a real river flows along the bottom of the Black Sea. It originates in the Bosphorus Strait and extends almost a hundred kilometers into the water column. According to unverified (yet) data from scientists, during the formation of the Black Sea, when the isthmus between the Crimean plain and the Mediterranean Sea was destroyed, the water that filled the territory of the present Black Sea formed a network of gutters in the ground. Today, an underwater river with salt water flows along one of them, which does not change its direction.
Why doesn't the water of an underwater river mix with sea water? It's all about the difference in densities and temperatures. The underwater river is several degrees colder than the sea. And denser due to the high salt content, because it is fed by the saltier Mediterranean Sea. The river flows along the bottom, carrying its waters to the bottom plains. These plains, like deserts on land, have virtually no life. The underwater river brings oxygen and food to them, which is very useful, given the abundance of hydrogen sulfide in the depths of the Black Sea. It is possible that there is life in these plains. Life under the “sea of hydrogen sulfide” located under the Black Sea. This is an intriguing play on words.
By the way, there is a guess that the ancient Greeks knew about the existence of the underwater river. Swimming out to sea, they threw a load attached to a rope from the ship. The river pulled the cargo, and with it the ship, making the work of the sailors easier.
Conclusion
So, today we found out who the inhabitants of the Black Sea are. The list and names helped us get to know them better. We also learned how the Black Sea differs from others, and what mysteries of nature are hidden behind its powerful waters. Now, when you go on vacation to your favorite sea, you will have something to surprise your friends and something to tell your inquisitive children.
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Main environmental problems of the Black Sea
Currently, the Black Sea is an important part of the Atlantic Ocean and covers an area of 420,325 km2. It is home to more than three thousand species of flora and fauna. A notable feature is the fact that all of the above-described diversity is found only at a depth of no more than 150 m. Further, falling below this mark, right down to the very bottom, one can observe a complete absence of life forms, with rare exceptions in the form of anaerobic bacteria. This is explained by the fact that the deep layers of water are a saturated solution of hydrogen sulfide. This is a destructive environment for all creatures that require oxygen for normal functioning.
Black Sea: environmental problems
Like any other modern body of water, this sea is subject to the negative influence of anthropogenic factors. Every year hundreds of tons of harmful substances are dumped into its basin. Such pollutants can safely include all organic and mineral fertilizers, which generously fertilize the soil to obtain a better harvest. It is they that, when they enter the sea and accumulate in the water column, provoke the active reproduction of phytoplankton. When such living organisms die, they consume the oxygen contained in the water masses, and thereby create certain problems. The Black Sea is covered with a whole layer of dead algae, which becomes larger and larger every year. Under the influence of this factor, oxygen deficiency is observed in the near-bottom areas.
Environmental problems of the Black Sea are also determined by the following negative factors:
1. Pollution of rivers flowing into it with sewage rainwater. This entails not only a decrease in water transparency and sea blooms, but also the destruction of multicellular algae.
2. Pollution of water masses with oil products. Such environmental problems of the Black Sea are most common in the western part of the water area, where many ports and a large number of tanker traffic are located. As a result, there is the death of many representatives of flora and fauna, disruption of their normal life activities, as well as deterioration of the atmosphere due to the evaporation of oil and its derivatives.
3. Pollution of water masses with human waste products. Such environmental problems of the Black Sea are the result of the discharge of untreated and poorly treated wastewater. The main burden falls on the northwestern part of the region. The main spawning grounds for fish and breeding grounds for various species of animals and birds are also located there. Another significant factor is the active development of the coastline. As a result of this, the bottom surface of the Black Sea shelf is contaminated with cement dust and residues of chemicals used in construction.
4. Negative factors can also include mass fishing, which entails an inevitable and global restructuring of marine ecosystems.
These are the main environmental problems of the Black Sea.
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Black Sea, features, nature, wildlife, islands
The Black Sea is the sea of the Atlantic Ocean. It is connected by the Kerch Strait with the Sea of Azov, the Bosphorus Strait with the Marmara Strait. The area of the Black Sea is 422,000 km2, surrounded on all sides by the landmass of the Eurasian continent. Due to this, it has difficulty exchanging water with the ocean, so there are no ebbs and flows. The maximum depth of the Black Sea is 2210 meters, the average reaches 1240 meters. The length of the coastline is 4340 km. It washes the shores of Ukraine, Russia, Bulgaria, Turkey, Romania, Georgia and Abkhazia.
The ancient Greek name of the Black Sea is Pont Aksinsky, which translated meant “Inhospitable Sea”. It received its modern name in the 13th century, but scientists still cannot come to a common conclusion about what exactly it means.
Previously, tens of millions of years ago, in its place was the ancient Tethys Ocean. Subsequently, the earth's crust and continents moved, and the sea gradually turned into an enclosed body of water. This happened approximately a million years ago, when the Caucasus and Crimean mountains were formed.
Exploring the bottom of the Black Sea at depths of about 100 meters, archaeologists came to the conclusion that it was once an area with fertile lands on which settlements were located during the Neolithic period. Relatively recently, eight thousand years ago, the Bosporus Strait was formed by an earthquake, thanks to which today the Black Sea mixes with the Mediterranean. It led to the flooding of the area that was located around the then small reservoir. Scientists disagree on how quickly this happened, some admit that the water could advance at a speed of up to 1.5 km per day.
The water temperature in the Black Sea fluctuates depending on the depth. In coastal areas it can reach +30 degrees in summer and +8 degrees in winter. This top layer is oxygenated and rich in organisms. In the lower layer, which starts at approximately 150 meters, the temperature is approximately +8 degrees; this layer is filled with hydrogen sulfide and there is no life in it. The salinity of the Black Sea in the upper layer is 18 ppm, in the lower layer it reaches 22.5 ppm. Water transparency averages 7 meters; off the southern coast of Crimea it can reach 18-20 meters.
Great excitement is caused by hydrogen sulfide in the Black Sea, which accumulates as a result of the activity of microspira bacteria. This gas has explosive properties, which has given rise to rumors that the sea could become the source of a worldwide catastrophe in the future. In fact, its concentration percentage is too small for such an effect to occur, so the explosion of the Black Sea does not threaten the planet.
The Black Sea islands are small, the largest of them - Zmeiny and Berezan - do not even reach 1 square kilometer in area. Several large rivers flow into the Black Sea - the Dnieper, Dniester, Danube - and more than 300 small ones.
The underwater world of the Black Sea is quite diverse. These are more than 2,500 species of animals and 270 species of algae. For the most part, these are species that live at shallow depths and are unpretentious to living conditions. There are several species of mammals, dolphins and seals, and there are also dangerous animals.
The resources of the Black Sea are also varied. They include large deposits of oil and natural gas, minerals and chemical raw materials. It is rich in fish, shellfish and algae, which are used in the food industry.
Today, the Black Sea basin is widely exploited by people. It is difficult to overestimate its transport importance - it is mainly freight transport between countries, ferry crossings, and transport corridors. The largest ports of the Black Sea are Kerch, Sevastopol, Yalta, Evpatoria in Crimea, Ukraine; Odessa - in Ukraine; Novorossiysk and Sochi in Russia; Varna - Bulgaria; Sukhum – Georgia; Samsun, Trabzon - Türkiye; Constanta - Romania. A deep-sea gas pipeline runs along the bottom, connecting Turkey and Russia. Industrial fishing and oil and gas production are developed. Coastal areas are widely used for recreational purposes. In connection with all this, the ecology of the Black Sea, in general, is quite unfavorable: it is polluted with oil products, human waste, and also, due to the influence of the anthropogenic factor, the fauna of the Black Sea has greatly changed and mutated.
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The meaning of the Black Sea | Kratkoe.com
What is the significance of the Black Sea for people and nature, you will learn by reading this article.
The meaning of the Black Sea
The Black Sea belongs to the Atlantic Ocean basin. It is connected to the Sea of Azov by the Kerch Strait and the Sea of Marmara by the Bosphorus Strait. Even the ancient Greeks knew about it, and it was called Pont Aksinsky, that is, “inhospitable sea.” This sea received its modern name in the 13th century and scientists are still at a loss as to why it was named.
Economic use of the Black Sea
The Black Sea is rich in resources that are used by humans. There are large deposits of natural gas and oil, chemical and mineral raw materials near the coastlines and on the shelf.
The Black Sea is also famous for its biological resources: algae, fish, shellfish. They are widely used in the food industry. Laminaria and phyllophora are extracted from algae here, from which medicines are made. Cystoseira (brown algae) and zostera (sea grass) reserves are used less.
Every year people catch tons of shrimp and mussels, fish and even dolphins. All this goes to the food industry.
The types of economic activities of people associated with the Black Sea are not limited to fishing and oil production. Today its pool is actively exploited by people. Its importance as a transport route is especially important: freight transport, transport corridors and ferry crossings take place across the Black Sea every day. It is also used as a recreational area, which brings good profits to the country, washed by the sea, during the season.
The most important ports of the Black Sea
Among the largest ports of the Black Sea are:
- Evpatoria, Sevastopol, Kerch, Yalta (Crimea)
- Sochi and Novorossiysk (Russia)
- Odessa, Ukraine)
- Varna (Bulgaria)
- Sukhum (Georgia)
- Trabzon and Samsun (Türkiye)
- Constanta (Romania)
Environmental problems of the Black Sea
Human activity in the Black Sea has led to an unfavorable environmental situation. It is heavily polluted with petroleum products and waste. Due to anthropogenic influence, the fauna of the sea has mutated.
The waste mostly comes with the waters of the Danube, Prut and Dnieper. The most pollution of the Black Sea with oil film is observed near the Caucasian coast and the Crimean Peninsula. Along the coast there are areas with an excess of toxic substances: cadmium, copper ions, lead and chromium.
Also in the Black Sea there is a process of water bloom due to lack of oxygen. Metals and pesticides, nitrogen and phosphorus enter it with river waters. Phytoplankton, absorbing these elements, multiply too quickly and the water “blooms”. In this case, bottom microorganisms die. When they rot, they cause hypoxia in mussels, juvenile sturgeon, squid, crabs, and oysters.
The coast and the bottom of coastal zones are polluted with household garbage, which can decompose in salt water for decades, or even centuries. This releases toxic substances into the water.
We hope that from this article you learned the importance of the nature of the Black Sea.
kratkoe.com
Black Sea
The Black Sea is an internal sea. Belongs to the Atlantic Ocean basin. It is connected to the Sea of Marmara through the Bosphorus Strait, then through the Dardanelles Strait (both straits are called the Black Sea) it is connected to the Aegean Sea and through the Kerch Strait it is connected to the Mediterranean Sea. From the north, the Crimean Peninsula juts out into the sea. The Black Sea serves as the water boundary separating Asia Minor and Europe. There are a number of hypotheses regarding the reasons for the origin of the name Black Sea: There are many hypotheses about the origin of the name Black Sea. According to one version, the Turkish and other conquerors who tried to conquer the population of the coast received very violent rebuff from the Circassians, Circassians and other tribes living here. For this reason, the sea was nicknamed inhospitable, Karaden-giz - Black.
According to a number of researchers, another reason that influenced the name of the sea is the color of the water during storms - it darkens significantly. Another hypothesis is related to the “color” designation of the cardinal directions, adopted in a number of Asian countries, where “black” denoted the north, respectively, the Black Sea - the northern sea. One common hypothesis is that the name is associated with memories of the Bosphorus breakthrough 7500-5000 years ago, which caused a catastrophic rise in sea level by almost 100 meters and in turn led to the flooding of a vast shelf zone and the formation of the Sea of Azov.
The Black Sea occupies an area equal to 422,000 square kilometers (other data indicate 436,400 square kilometers. In outline, the Black Sea is an oval, the axis of which is 1,150 km. In length from the north to the south, the Black Sea stretches for 580 km. Its maximum depth is equal to 2210 m. The average depth is in the range of 1220 - 1240 m.
The Black Sea has a volume of water of 555 thousand cubic kilometers. A characteristic feature of the sea is the complete absence of life at depths of 160 - 200 meters, due to the saturation of the water with hydrogen sulfide. (with the exception of some anaerobic bacteria).
The only large peninsula is Crimean. The largest bays are: Yagorlytsky, Tendrovsky, Dzharylgachsky, Karkinitsky, Kalamitsky and Feodosia in Ukraine, Varna and Burgas in Bulgaria, Sinop and Samsun - on the southern shores of the sea. In the north and northwest, estuaries overflow at the confluence of rivers. The total length of the coastline is 3400 km.
A number of sections of the sea coast have their own names: the southern coast of Crimea in Ukraine, the Black Sea coast of the Caucasus in Russia, the Rumelian coast and the Anatolian coast in Turkey. In the west and north-west the banks are low-lying, steep in places; in Crimea - mostly lowland, with the exception of the southern mountainous shores. On the eastern and southern shores, the spurs of the Caucasus and Pontic mountains come close to the sea.
There are almost no islands in the Black Sea. The largest are Berezan and Zmeiny (both with an area of less than 1 sq. km.). The following largest rivers flow into the Black Sea: Danube, Dnieper, Dniester, as well as smaller Mzymta, Rioni, Kodori, Inguri (in the east of the sea), Chorokh, Kyzyl-Irmak, Ashley-Irmak, Sakarya (in the south), Southern Bug ( in the north).
The average January temperature in the northern part of the Black Sea is 3 °C, but can drop to - 30 °C. In the territories adjacent to the southern coast of Crimea and the Caucasus coast, winter is much milder: temperatures rarely drop below 0 °C. Snow, however, periodically falls in all areas of the sea. The average July temperature in the north of the sea is + 22 +23°C. Maximum temperatures are not so high due to the softening effect of the water reservoir and usually do not exceed 35 °C.
The flora of the sea includes 270 species of multicellular green, brown, and red bottom algae (Cystoseira, Phyllophora, Zostera, Cladophora, Ulva, Enteromorpha, etc.). The phytoplankton of the Black Sea contains at least six hundred species. Among them are dinoflagellates - armored flagellates (prorocentrum micans, ceratium furca, small Scrippsiella trochoidea, etc.), dinoflagellates (dinophysis, protoperidinium, alexandrium), various diatoms, etc.
The fauna of the Black Sea is noticeably poorer than that of the Mediterranean. The Black Sea is home to 2.5 thousand species of animals (of which 500 species are unicellular, 160 species of vertebrates - fish and mammals, 500 species of crustaceans, 200 species of mollusks, the rest are invertebrates of various species), for comparison, in the Mediterranean - about 9 thousand .species. Among the main reasons for the relative poverty of the marine fauna: a wide range of water salinities, moderately cold water, and the presence of hydrogen sulfide at great depths.
In this regard, the Black Sea is suitable for the habitat of fairly unpretentious species, at all stages of development of which great depths are not required. The bottom of the Black Sea is inhabited by mussels, oysters, pecten, as well as the predator mollusk rapana, brought with ships from the Far East. Numerous crabs live in the crevices of the coastal rocks and among the stones, there are shrimps, various types of jellyfish are found (the most common are Corneros and Aurelia), sea anemones, and sponges.
Among the fish found in the Black Sea: various types of gobies (bighead goby, whip goby, round goby, martovy goby, rotan goby), Azov anchovy, Black Sea anchovy, dogfish shark, glossa flounder, mullet of five species, bluefish, hake (hake), sea ruff, red mullet (common Black Sea mullet), haddock, mackerel, horse mackerel, Black Sea-Azov herring, Black Sea-Azov sprat, etc. There are sturgeon (beluga, stellate sturgeon, Black Sea-Azov ( Russian) and Atlantic sturgeon).
Among the dangerous fish of the Black Sea are the sea dragon (the most dangerous - the spines of the dorsal fin and gill covers are poisonous), the Black Sea and noticeable scorpionfish, the stingray (sea cat) with poisonous spines on the tail.
The most common birds are gulls, petrels, diving ducks, cormorants and a number of other species. Mammals are represented in the Black Sea by two species of dolphins (the common dolphin and the bottlenose dolphin), the Azov-Black Sea harbor porpoise (often called the Azov dolphin), and the white-bellied seal. Some species of animals that do not live in the Black Sea are often brought into it through the Bosporus and Dardanelles straits by currents or swim on their own.
Favorable climatic conditions in the Black Sea region determine its development as an important resort region. The largest resort areas on the Black Sea include: The southern coast of Crimea (Yalta, Alushta, Sudak, Evpatoria, Koktebel, Feodosia) in Ukraine, the Black Sea coast of the Caucasus (Anapa, Gelendzhik, Sochi) in Russia, Pitsunda, Gagra and Batumi in Georgia, Golden sands and Sunny Beach in Bulgaria, Mamaia, Eforie in Romania. The Black Sea coast of the Caucasus is the main resort region of the Russian Federation.
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| Central City Library named after. L.N. Tolstoy Information and bibliographic department Sevastopol The list dedicated to the Black Sea, its history, biological resources, modern problems, was compiled on the basis of the funds of the Central City Hospital named after. Tolstoy and includes books, articles from collections and periodicals for 2002 – 2012. In some cases, earlier editions were used. The list consists of five sections:
members of public environmental organizations - everyone who is not indifferent to the fate of the sea. Compiled by Pavlova T.F., chief bibliographer On October 31, 1996, government delegations of the Black Sea countries adopted in Istanbul a strategic action plan to save the Black Sea. Now this date is celebrated as International Black Sea Day. But perhaps it was on the same day many centuries ago that a catastrophe occurred, as a result of which, through a gap called today the Bosporus, the waters of the Mediterranean Sea poured into the depression between the modern Middle East and the Balkans and created a new sea, which the Hellenes at first called inhospitable - Pontus Aksinsky, and centuries later - Euxinian - hospitable? The Black Sea has a long geological history. Its resources are varied. Sea warmth, favorable climate, beaches - huge opportunities for relaxation, recreational resources. Fish, shellfish, algae - these biological resources are very important in the food balance of the Black Sea states. The Black Sea is a huge hub of transport communications. Since the time of Herodotus, who visited the Black Sea in the 5th century. BC, our knowledge of the sea and its shores has increased immeasurably. Its shores were carefully described, the bottom topography and soils were studied. Currents, the chemical composition of water and its temperature at different depths have been studied, and the laws of interaction between the sea and the atmosphere have been successfully learned. The flora and fauna of the sea is diverse. Classes of organisms have been registered, data have been accumulated on the numbers of many species, places and times of their aggregations, habits, nutrition, reproduction and importance of marine animals for humans. Now the Black Sea is one of the most studied on the globe. However, many problems still need to be solved by science and practice in order to make fuller use of the resources of the Black Sea, without causing damage to the reservoir itself. Caring for the sea and protecting it from pollution is one of the most pressing tasks today.
V. Bays of Sevastopol
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Resources of the Black and Azov Seas
Mineral resources are, first of all, natural gas and oil deposits in the central part of the Azov Sea bottom and the Black Sea shelf. In the coastal strip, building materials are mined (pebbles, gravel, sand), placers of ore minerals and even diamonds are found. Large deposits of iron-manganese nodules have been discovered at the bottom of the Black Sea. In the future, it is possible to extract hydrogen sulfide gas from the depths of the Black Sea. It is a flammable gas that is used to produce sulfuric acid. From the brine of the Sivash Bay (salinity from 100 to 200% o) rock salt, magnesium oxide, bromine, etc. are extracted.
The recreational resources of the seas are great (natural prerequisites for organizing recreation for the population). In particular, the length of sea beaches is about 1000 km, and 4 million people can relax on them at the same time.
Questions and tasks
How are the features of the nature of the seas reflected in their geographical names? 2. Using table 4 of the flyleaf, compare the nature of the two seas washing Ukraine. Describe the connections between the nature of the seas and land of Ukraine. Describe the natural resources and economic importance of the seas. Are negative changes occurring in the natural complexes of the seas?
Draw up a diagram of the connections between the natural complexes of the seas and land of Ukraine. Show the flows of substances in different states of aggregation. 7. What does the fact indicate that 176 km3 of water per year is transported through the Bosphorus Strait by deep currents, and 340 km3 by surface currents?
On the contour map, indicate with numbers the elements of the coastline of the seas KARKINITSKY, Kalamitsky, Dzharylgachsky, Feodosiysky, Sivash, Taganrog, Berdyansk. Estuaries Dniester, Dnieper-Bug, Kuyalnitsky, Utlyutsky, Molochny. Strait: Kerch, Crimean, Tarkhankutsky, Kerch islands. Spit (narrow strips of land, islands and peninsulas formed from sediment carried by coastal currents) Berezan, Tendrovskaya, Dzharylgach, Arabatskaya Strelka, Biryuchiy Island, Tuzla. Islands: Zmeiny, Lebedine.
In what cases is it permissible to use primary fire extinguishing agents? Designation of batteries
The Black Sea is home to 184 species and subspecies of fish, of which 144 are exclusively marine, 24 are anadromous or partially anadromous, 16 are freshwater. In recent years, the ichthyocenosis of the Black Sea has been replenished by the Far Eastern mullet Mugil so-iuy Basilewsky, which has successfully acclimatized in the Azov-Black Sea basin.
Marine fish species of the Black Sea are usually divided into 4 groups: permanently inhabiting (Black Sea anchovy race, Black Sea horse mackerel, Black Sea sprat, Kalkan); wintering in the Black Sea, but spawning and fattening in the Sea of Azov (Azov race of anchovy, Kerch race of herring); wintering and spawning in the Black Sea, but feeding in the Azov Sea (mullet, Black Sea mullet); developing the Black Sea as a spawning and feeding area, but wintering or spawning in the Marmara and Aegean Seas (bonito, mackerel).
V. Vodyanitsky (1941) gave the following diagram of the food relationships of Black Sea fish. (according to L.A. Zenkevich. 1963) (Fig. 1.)
The number of most Black Sea fish depends not only on the conditions of their existence in the Black Sea, but also on the conditions of spawning, feeding or wintering in adjacent seas, which determines the complex type of dynamics of the raw material base of the entire sea.
Of the total number of fish, about 20% serve as commercial fish. In the 70s and 80s, the USSR added about 200 thousand tons of fish and seafood to the Black Sea. The basis of the catch was the Black Sea race of anchovy, sprat, whiting, horse mackerel, and katran (Table 1). The catch of other fish - mullet, mullet, herring, perch, etc. off the coast of the former USSR is very limited due to their low numbers.
Fishery research has established that significant interannual fluctuations in the number of fish in the Black Sea are accompanied by changes in the species composition of catches. So from the late 40s to the mid 50s. In the Black Sea, planktivorous fish dominated - anchovy and Black Sea horse mackerel. Subsequently, until the 60s, the catch was dominated by
Table 1 USSR catches of the main commercial fish of the Black Sea (1975 - 1990), thousand. T.
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Game fish |
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Horse mackerel |
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* Black Sea anchovy (anchovy) with Azov bycatch during fishing in the south-eastern part of the sea. |
Since 1974, more than 95% of the catch has been anchovy, Black Sea sprat, whiting and horse mackerel. According to FAO, the total catch of the listed fish in 1971-1984. tended to increase, which is associated with the expansion of the scale of their fishing.
Various researchers have estimated the initial stocks and production of fish in the Black Sea at 0.5-5.7 million tons and 0.25-2.9 million tons, respectively. Such a large range is associated with both the methodological approach and large interannual fluctuations number of commercial fish in the reservoir. In addition, at present, anthropogenic factors are a significant “regulator” of the number of commercial fish, which influence not only the abiotic, but also the biotic part of the Black Sea ecosystem.
The results of Ukrainian research over the past ten years allow us to speak about the initial stock of pelagic fish (anchovy, horse mackerel, sprat) at the level of 2-3 million tons, demersal fish (merlang, katran, galkan, etc.) - 0.3-0.7 million .T. This assessment did not include information on Mediterranean migrants (lufal, mackerel, bonito), since their migrations to the former USSR zone have practically not been observed in the last 20 years.
The commercial importance of the Black Sea is determined not only by fish resources, but also by significant reserves of invertebrates (mussels) and algae (phyllophora), the size of populations and associations of which undergo significant changes under the influence of various types of economic activity.
In addition to fish, invertebrates and algae, the Black Sea is home to mammals. So, here there are three species of dolphins (white-sided, bottlenose and Azov), which have long been hunted by all Black Sea countries. The number of dolphins was previously high, and the total production exceeded 10 thousand tons per year, which led to a sharp decrease in their stocks. Since 1966, dolphin fishing has been prohibited.
The general fishing regime in the Black Sea is determined by the principles of rational use of fish resources in accordance with the state of the stocks of the exploited objects. However, due to the lack of concerted action on industrial exploitation and biological resources, problems arise in international fisheries regulation.(2)
Mineral wealth of the Black Sea
The Black Sea is currently the most promising for oil and gas resources. And the first ferromanganese nodules in the Black Sea were discovered back in 1890 by N.I. Andrusov. A little later, such scientists as Zernov S.A., Milashevich K.O., Titov A.G., and Strakhov N.M. were engaged in their detailed study. Currently, three different nodule belts have been explored and discovered in the Black Sea: west of the Rioni River delta, south of Cape Tartankhut, as well as on the continental slope east of Sinop and on the Turkish part of the shelf.
In addition to all this, the coast and bottom of the Black Sea have recently been considered as the main places where tin, diamonds, platinum, ore metals and titanium can be mined. The Black Sea is also a storehouse of building materials such as shell rock, pebbles and sand.
Mineral wealth of the Azov Sea
The shallowest sea is rich in minerals, hidden not only under water, at the bottom, but often even in the depths of the seabed. The most important among its hidden treasures are the potential oil and gas resources of the water area. Gas fields (Kerch-Taman region - in the south, in the vicinity of the village of Strelkovoe - in the west, Beisugskoye - in the east, Sinyavinskoye - in the northeast) seem to frame the entire Sea of Azov. Throughout the local water area and around, the main promising oil and gas bearing horizon is the Lower Cretaceous sediments, to a lesser extent - Paleocene, Eocene, Maikop, Miocene and even Pliocene rocks. From the point of view of oil content, the Maikop ones are the most interesting.
The total thickness of the sedimentary cover in the southern part of the sea - in the Indolo-Kuban depression - is enormous and reaches 14 km. A significant part of this powerful section is promising for oil and gas.
Along the shores of its western half is the Azov-Black Sea Neogene iron ore province, represented by oolitic iron ores of Cimmerian age. In the northwestern part of the sea, within the so-called Molochansky graben, there are likely to be large deposits of iron ore with reserves of several billion tons. They are presumably localized along the northern slope of the Azov swell and within the entire negative structure of this graben.
Another type of mineral raw material supplied by the Sea of Azov is table salt. Sea salt is extracted from Sivash. And a lot: about 60 thousand tons.
Major minerals from the bottom of the seas
The first place among them is occupied by oil along with flammable gases, followed by iron and manganese ores, bauxite, limestone, dolomite and phosphorite.
Oil is a mixture of various hydrocarbons, i.e. compounds of carbon with hydrogen. It is fluid, capable of moving underground over considerable distances. During these movements, oil droplets scattered in rocks can accumulate into large oil deposits.
According to the teachings of academician I.M. Gubkin (1871-1939) oil was formed in sedimentary rocks of all geological eras. “It arose precisely in those cases where there were favorable conditions for sedimentation of a lagoonal, coastal or lacustrine nature, which contributed to the accumulation of organic material from which oil was subsequently formed.”
Oil and gas fields are found in foothill troughs, in subsidence zones of mountain ranges and in extensive tectonic depressions within platforms. Such places are favorable for the accumulation of thick layers of sandy-clayey or carbonate sediments. Along with these sediments, interspersed with them, the semi-decomposed remains of various organisms, mainly small, microscopic ones, accumulate. Some of this organic material gradually turns into oil over geological time. Water displaces oil from clays and other source rocks where it originated into coarsely porous rocks, or “reservoirs,” such as sands, sandstones, limestones and dolomites. If there is a layer above the reservoir that is impermeable to oil in the form of dense clay or other rock, then oil accumulates under such a seal, forming a deposit. The richest oil deposits are found in the crests of uplifted layers. In this case, the upper part of the arch under the impermeable layer is occupied by flammable gas, below is oil, and even lower is water (Fig. 1).
Rice. 1
That is why petroleum geologists first of all study the bends or structures of layers, look for underground vaults or other similar “traps” of oil placed by nature along the paths of its underground movement.
In some places, oil comes to the surface of the earth as a spring. At such sources it forms thin multi-colored films on the water. The same type of film is also found in ferruginous sources. Upon impact, the ferrous film breaks into sharp-angled fragments, and the oil film into round or elongated spots, which can then merge again.
The relatively rapid accumulation of sedimentary rocks is one of the necessary conditions for the formation of the oil source strata. Ores of iron, manganese, aluminum and phosphorus, on the contrary, accumulate very slowly, and even if the ore minerals of these metals are formed in the source strata, they turn out to be dispersed in them, not representing any interest for extraction.
Deposits of marine ores of iron, manganese, aluminum and phosphorus have the form of layers, sometimes short, sometimes stretching over long distances. The layers of some phosphorites stretch for tens and even hundreds of kilometers. For example, a layer of phosphorite from the “Kursk nugget” runs from Minsk through Kursk to Stalingrad.
All these ores were deposited in shallow places of the seas and lie among marine shallow sandy-clayey or calcareous rocks. The formation of iron, manganese and aluminum ores is characterized by a close connection with the adjacent land - with its composition, topography and climate. In a humid climate and with flat or hilly land topography, the flow of rivers is calm and therefore they carry little sand and clay and relatively many dissolved compounds of iron, and sometimes aluminum and manganese. During its decomposition, the dense vegetation of humid climate regions produces many acids that destroy rocks and allow the released compounds of iron, manganese and aluminum to move in dissolved form. In addition, dense vegetation protects the land from erosion, which also reduces the amount of sandy-clayey turbidity in rivers.
The composition of the rocks that make up the land, as well as the climate, determine the relative amount of ore elements removed from the land. Basic rocks, especially basalts and diabases, provide a lot of iron and manganese. In humid tropics, aluminum is more easily washed out from basalts and nepheline rocks, and more difficult from granites.
Rivers carry dissolved compounds of iron, manganese and aluminum into the sea, where they are deposited. If few contaminants are deposited at the same time, relatively pure ore deposits can form. Favorable places for the accumulation of these ores are calm bays or lagoons.
Slow accumulation of sediments can occur not only on platforms, but sometimes also in geosynclines. Since the main rocks (diabases, basalts and others) often came to the surface over large areas in geosynclinal areas, there were no less, but more opportunities for the accumulation of ores in them than on platforms. For the accumulation of sediments, it is also important that geosynclinal areas are not characterized throughout their entire area by instability of the earth’s crust or rapid accumulation of sediments. They contain areas that are at times relatively stable, which contributes to the slow accumulation of sedimentary rocks. Such areas are precisely of the greatest interest from the point of view of sedimentary ore formation.
At the beginning of industrialization, our Motherland experienced an urgent need for aluminum ores - bauxite. At that time, the prevailing theory here and abroad was that bauxite was formed on land as a result of tropical weathering. Academician A.D. Arkhangelsky, based on a detailed study of bauxites, came to a completely different conclusion. He found that the largest and highest quality bauxite deposits are not of land, but of marine origin and formed in geosynclines. Geological parties were sent to areas of geosynclinal marine sediments favorable for the formation of bauxite. These geological searches culminated in the discovery of a number of new rich bauxite deposits in Devonian marine sediments in the Urals, which provided our aluminum plants with domestic raw materials. The Devonian bauxites of the Urals were deposited, although in a geosynclinal region, but at such moments of its life when the accumulation of sediments occurred slowly, with interruptions and temporary retreats of the sea. Much of this bauxite was deposited on land in depressions among limestones.
The origin of phosphorite deposits is interesting. Due to the conditions of their formation, they do not have such a close connection with the land as metal ores. Phosphates dissolved in seawater are characterized by the fact that they are a very important and, moreover, scarce nutrient for marine organisms. Phosphates feed plants, which in turn are eaten by animals. Dead organisms, sinking to the bottom, take phosphorus with them. During their decomposition, they release it on the way to the bottom and partly at the bottom. As a result, the upper layers of water are depleted in phosphorus, and the lower layers are enriched with it. Starting from a depth of 150-200 m, its concentration is 5 or 10 times higher than at the surface of the water, and the highest concentrations of dissolved phosphates are formed in silt or groundwater. In these waters at the bottom of the sea, phosphates precipitate from solution. Phosphorites have the form of continuous layers, cavernous slabs or nodules of various types.
The origin of almost all phosphorite layers is associated with interruptions in the accumulation of sedimentary strata, which was especially noted by A.D. Arkhangelsk. This fact is apparently explained by the fact that phosphorites were deposited in relatively shallow water conditions, at depths of approximately 50-200 m, so that a slight rise in the seabed was enough for them to end up in the zone of wave erosion.
White chalk and limestone are also of marine origin. Both of them consist mainly of calcite or calcium carbonate and differ not in mineralogical or chemical composition, but in physical state - white chalk is soft, it is composed of tiny uncemented particles; limestone, on the contrary, is strong, the particles composing it are larger than in chalk.
Layers of white chalk come to the surface in many places in Ukraine, on the Don and on the Volga. More than half of the chalk consists of the remains of microscopic calcareous algae coccolithophores (Fig. 2). Modern coccolithophores swim near the surface of the water, moving with the help of their flagella. They inhabit mainly warm seas.
In addition to the remains of coccolithophores, microscopic calcite shells of rhizomes, or foraminifera, as well as mollusk shells and the remains of sea urchins, crinoids and flint sponges are often found in the Cretaceous.
The amount of remains of coccolithophores in chalk is usually 40-60 percent, rhizomes - 3-7 percent, other calcareous organisms - 2-6 percent, and the rest is powdery calcite, the origin of which has not yet been clarified.
The predominance of remains of calcareous algae in the composition of chalk was established back in the last century by Kyiv professor P. Tutkovsky and Kharkov professor A. Gurov
Limestones also largely consist of calcite organic remains - shells of mollusks and brachiopods, remains of echinoderms, calcareous algae and corals. Many limestones have changed so much that it is difficult to determine their origin by appearance. There are still disputes about such limestones: some say that the calcite in them was chemically precipitated from a solution of sea water, others argue that the limestone is composed of organic remains that have now been altered beyond recognition.
In his recently published work, Professor N.M. Strakhov proved that almost all marine limestones were formed due to the remains of calcareous organisms, and the chemical precipitation of calcium carbonate in the sea occurs in very limited quantities. Indeed, the white limestones of the Cretaceous period, widespread in the Crimea and the Caucasus, at first glance are extremely poor in organic remains, but upon careful study, a large number of remains of coccolithophores and rhizomes were found in them. This means that these limestones were previously chalk, and then became very compacted.
The use of limestone is very diverse. They are used as crushed stone for roads and railways, as rubble for laying foundations, and some of the densest ones are used for cladding buildings like marble. In such marbles one can see shells of brachiopods and mollusks, sea lilies, calcareous algae and corals. Limestones are also widely used for the production of lime and cement, for liming soils, in metallurgy, in the production of soda, glass, in the purification of sugar syrup and in the production of calcium carbide. Chalk, where high strength is not required from it, is used in the same way as limestone.
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