Causes and sources of water pollution. Natural sources of water pollution

Water is of great importance for all life on our planet. People, animals, and plants need it to live, grow and develop. Moreover, living organisms need clean water, not spoiled by foreign contaminants. Before the start of the industrial era, water in natural conditions was clean. But, as civilization developed, people began to pollute water sources with waste from their activities.

Natural sources of water that people use are rivers, lakes, and seas. Clean water is also obtained from underground sources using wells and boreholes. What are the sources of water pollution?

Industry
We live in an era of intense industrial activity. Water in industry is used in huge quantities, and after use is reset to industrial sewerage. Industrial wastewater is treated, but it cannot be completely purified. Numerous plants, factories and industries are sources of water pollution.

Oil production and oil transportation
Industry and transport require fuel, the production of which uses oil. Oil is produced both on land and at sea. The extracted oil is transported by huge sea tankers. In the event of accidents at oil production sites or transport accidents, spills of oil products occur on the water surface. A few grams of oil is enough to form a film of tens of square meters on the sea surface.

Energy
Thermal stations contribute to the deterioration of the quality of natural water. They use large quantities of water for cooling processes and discharge the heated water into open water bodies. The water temperature in such reservoirs rises, they begin to become overgrown with harmful algae, and the amount of oxygen in such water decreases. All this negatively affects living organisms living in such reservoirs. The ecological balance is disrupted and water quality deteriorates.

Household sphere
People need water, first of all, in everyday life. In every house, in every apartment, water is used for cooking, washing dishes, cleaning rooms, and also in bathrooms. Used water is removed from residential premises through sewage systems. Such water is subsequently purified in special purification devices, but it is very difficult to achieve complete purification. Therefore, one of the sources of water pollution in nature is municipal wastewater. These waters contain harmful chemicals, various microorganisms and small household waste.

Agriculture
Another source of pollution natural waters is agriculture. This type of human activity requires huge amounts of water. Numerous fields of crops need to be watered. Water is also needed for raising farm animals. Many artificial fertilizers are used in crop production. Water used to irrigate fertilized fields becomes contaminated by these fertilizers. And wastewater discharged from livestock complexes carries animal waste. With insufficient wastewater treatment in agriculture, natural water sources are polluted.

In our world, there are many sources of natural water pollution caused by human activities. It is impossible to refuse the benefits of civilization, therefore the only way to preserve the purity of natural waters is to continuously improve methods for purifying contaminated water.

WATER POLLUTION
changes in chemical and physical state or biological characteristics water, limiting its further use. For all types of water use, either the physical state changes (for example, when heated) or chemical composition water - when pollutants enter, which are divided into two main groups: those that change over time in the aquatic environment and those that remain unchanged in it. The first group includes organic components of domestic wastewater and most industrial waste, such as waste from pulp and paper mills. The second group consists of many inorganic salts, such as sodium sulfate, which is used as a dye in the textile industry, and inactive organic substances such as pesticides.
SOURCES OF POLLUTION
Settlements. The most well-known source of water pollution and the one that has traditionally received the most attention is domestic (or municipal) wastewater. Urban water consumption is usually estimated based on the average daily water consumption per person, which in the United States is approximately 750 liters and includes water for drinking, cooking and personal hygiene, for the operation of household plumbing fixtures, as well as for watering lawns and lawns, extinguishing fires, and washing streets and other urban needs. Almost all used water goes down the drain. Since a huge volume of feces enters wastewater every day, the main task of city services when processing domestic wastewater in the sewers of treatment plants is to remove pathogenic microorganisms. When insufficiently treated faecal waste is reused, the bacteria and viruses it contains can cause intestinal diseases (typhoid, cholera and dysentery), as well as hepatitis and polio. Soap, synthetic washing powders, disinfectants, bleaches and other household chemicals are present in dissolved form in wastewater. Paper waste comes from residential buildings, including toilet paper and baby diapers, waste from plant and animal food. Rain and melt water flows from the streets into the sewer system, often with sand or salt used to accelerate the melting of snow and ice on the roadways and sidewalks.
Industry. In industrialized countries, the main consumer of water and the largest source of wastewater is industry. Industrial wastewater into rivers is 3 times larger than municipal wastewater. Water performs various functions, for example, it serves as a raw material, a heater and a coolant in technological processes, in addition, it transports, sorts and washes different materials. Water also removes waste at all stages of production - from the extraction of raw materials, the preparation of semi-finished products to the release of final products and their packaging. Since it is much cheaper to throw away waste from various production cycles than to process and dispose of it, a huge amount of various organic and non-organic substances are discharged with industrial wastewater. organic matter. More than half of the wastewater entering water bodies comes from four main industries: pulp and paper, oil refining, organic synthesis industry and ferrous metallurgy (blast furnace and steel production). Due to the growing volume of industrial waste, the ecological balance of many lakes and rivers is being disrupted, although most of the wastewater is non-toxic and non-lethal to humans.
Thermal pollution. The largest single use of water is in electricity generation, where it is used primarily for cooling and condensing steam generated by turbines in thermal power plants. At the same time, the water heats up by an average of 7 ° C, after which it is discharged directly into rivers and lakes, being the main source of additional heat, which is called “thermal pollution”. There are objections to the use of this term, since increasing water temperature sometimes leads to beneficial environmental consequences.
Agriculture. The second main consumer of water is agriculture, which uses it to irrigate fields. The water flowing from them is saturated with salt solutions and soil particles, as well as chemical residues that help increase productivity. These include insecticides; fungicides that are sprayed over orchards and crops; herbicides, a famous weed control agent; and other pesticides, as well as organic and inorganic fertilizers containing nitrogen, phosphorus, potassium and other chemical elements. Except chemical compounds, large volumes of feces and other organic residues from farms where meat and dairy cattle, pigs or poultry are raised enter rivers. A lot of organic waste also comes from the processing of products. Agriculture(when cutting meat carcasses, processing leather, producing food products and canned food, etc.).
EFFECTS OF POLLUTION
Pure water is transparent, colorless, odorless and tasteless, inhabited by many fish, plants and animals. Polluted waters are cloudy, with unpleasant smell, not suitable for drinking, often contain huge amounts of bacteria and algae. Water self-purification system (aeration running water and sedimentation of suspended particles to the bottom) does not work due to the excess of anthropogenic pollutants in it.
Reduced oxygen content. Organic substances contained in wastewater are decomposed by enzymes of aerobic bacteria, which absorb oxygen dissolved in water and release carbon dioxide as organic residues are absorbed. Commonly known breakdown end products are carbon dioxide and water, but many other compounds can be formed. For example, bacteria convert nitrogen contained in waste into ammonia (NH3), which, when combined with sodium, potassium or other chemical elements, forms salts of nitric acid - nitrates. Sulfur is converted into hydrogen sulfide compounds (substances containing the radical -SH or hydrogen sulfide H2S), which gradually turn into sulfur (S) or sulfate ion (SO4-), which also forms salts. In waters containing fecal matter, plant or animal residues coming from enterprises Food Industry, paper fibers and cellulose residues from pulp and paper industry enterprises, the decomposition processes proceed almost identically. Because the aerobic bacteria use oxygen, the first result of the decomposition of organic residues is a decrease in the oxygen content dissolved in the receiving waters. It varies depending on temperature, and also to some extent on salinity and pressure. Fresh water at 20° C and intensive aeration contains 9.2 mg of dissolved oxygen in one liter. As the water temperature increases, this indicator decreases, and when it cools, it increases. According to the standards in force when designing municipal treatment facilities, for the breakdown of organic matter contained in one liter of municipal wastewater of normal composition at a temperature of 20 ° C, approximately 200 mg of oxygen is required over 5 days. This value, called biochemical oxygen demand (BOD), is used as the standard for calculating the amount of oxygen required to treat a given volume of wastewater. The BOD value of wastewater from leather, meat processing and sugar refinery industries is much higher than that of municipal wastewater. In small watercourses with fast currents, where the water is intensively mixed, oxygen coming from the atmosphere compensates for the depletion of its reserves dissolved in the water. At the same time, carbon dioxide formed during the decomposition of substances contained in wastewater evaporates into the atmosphere. This reduces the period of adverse effects of organic decomposition processes. Conversely, in bodies of water with weak currents, where the waters mix slowly and are isolated from the atmosphere, an inevitable decrease in oxygen content and an increase in carbon dioxide concentration entail serious changes. When the oxygen content decreases to a certain level, fish die and other living organisms begin to die, which, in turn, leads to an increase in the volume of decomposing organic matter. Most fish die due to poisoning from industrial and agricultural wastewater, but many also die from a lack of oxygen in the water. Fish, like all living things, absorb oxygen and release carbon dioxide. If there is little oxygen in the water, but a high concentration of carbon dioxide, the intensity of their respiration decreases (it is known that water with a high content of carbonic acid, i.e. carbon dioxide dissolved in it, becomes acidic).

[s]tbl_dirt.jpg. TYPICAL WATER POLLUTANTS IN SOME INDUSTRIES

In waters experiencing thermal pollution, conditions are often created that lead to the death of fish. There, the oxygen content decreases, since it is slightly soluble in warm water, but the need for oxygen increases sharply, since the rate of its consumption by aerobic bacteria and fish increases. Adding acids, such as sulfuric, with drainage waters from coal mines also significantly reduces the ability of some fish species to extract oxygen from water. Biodegradability. Man-made materials that biodegrade increase the load on bacteria, which in turn increases the consumption of dissolved oxygen. These materials are specially created in such a way that they can be easily processed by bacteria, i.e. decompose. Natural organic matter is usually biodegradable. In order for artificial materials to have this property, the chemical composition of many of them (for example, detergents and cleaners, paper products, etc.) was changed accordingly. First synthetic detergents were resistant to biodegradation. When huge clouds of soap suds began to accumulate at municipal wastewater treatment plants and disrupt the operation of some water treatment plants due to contamination with pathogenic microorganisms or float downstream in rivers, public attention was drawn to this circumstance. Detergent manufacturers have solved the problem by making their products biodegradable. But this decision also provoked negative consequences, since it led to an increase in the BOD of watercourses receiving wastewater, and, consequently, an acceleration in the rate of oxygen consumption.
Formation of gases. Ammonia is the main product of microbiological decomposition of proteins and animal excretions. Ammonia and its gaseous amine derivatives are formed both in the presence and absence of oxygen dissolved in water. In the first case, ammonia is oxidized by bacteria to form nitrates and nitrites. In the absence of oxygen, ammonia does not oxidize, and its content in water remains stable. As the oxygen content decreases, the resulting nitrites and nitrates are converted to nitrogen gas. This happens quite often when water flowing from fertilized fields and already containing nitrates ends up in stagnant reservoirs, where organic residues also accumulate. The bottom silts of such reservoirs are inhabited by anaerobic bacteria that develop in an oxygen-free environment. They use the oxygen present in the sulfates and form hydrogen sulfide. When there is not enough available oxygen in the compounds, other forms of anaerobic bacteria develop, which cause the rotting of organic matter. Depending on the type of bacteria, carbon dioxide (CO2), hydrogen (H2) and methane (CH4) are formed - a colorless and odorless flammable gas, which is also called swamp gas. Eutrophication, or eutrophication, is the process of enriching water bodies with nutrients, especially nitrogen and phosphorus, mainly of biogenic origin. As a result, the lake gradually becomes overgrown and turns into a swamp filled with silt and decaying plant debris, which eventually dries out completely. IN natural conditions This process takes tens of thousands of years, but as a result of anthropogenic pollution it proceeds very quickly. For example, in small ponds and lakes under human influence it is completed in just a few decades. Eutrophication increases when plant growth in a body of water is stimulated by nitrogen and phosphorus contained in fertilizer-laden agricultural runoff, cleaning products and other waste. The waters of the lake receiving this wastewater provide a fertile environment in which aquatic plants grow vigorously, taking over the space where fish usually live. Algae and other plants, dying, fall to the bottom and are decomposed by aerobic bacteria, which consume oxygen for this, which leads to the death of fish. The lake is filled with floating and attached algae and other aquatic plants, as well as small animals that feed on them. Blue-green algae, or cyanobacteria, make the water taste like pea soup with a foul odor and fishy taste, and coat rocks in a slimy film.
Thermal pollution. The temperature of water used in thermal power plants for cooling steam rises by 3-10 ° C, and sometimes up to 20 ° C. The density and viscosity of heated water differs from the properties of more cold water receiving pool, so they are mixed gradually. Warm water cools either around the outlet or in a mixed stream flowing downstream of the river. Powerful power plants noticeably heat the waters in the rivers and bays on which they are located. In the summer, when the demand for electrical energy for air conditioning is very high and its production increases, these waters often overheat. The concept of “thermal pollution” refers specifically to such cases, since excess heat reduces the solubility of oxygen in water, accelerating the rate of chemical reactions and, therefore, affects the life of animals and plants in water intake basins. Exist vivid examples how, as a result of rising water temperatures, fish died, obstacles arose in the path of their migrations, algae and other lower weeds multiplied rapidly, and untimely seasonal changes in the aquatic environment occurred. However, in some cases, fish catches increased, the growing season extended, and other beneficial effects were observed. Therefore, we emphasize that for a more correct use of the term “thermal pollution” it is necessary to have much more information about the effect of additional heat on the aquatic environment in each specific place.
Accumulation of toxic organic substances. The stability and toxicity of pesticides have ensured success in the fight against insects (including malarial mosquitoes), various weeds and other pests that destroy crops. However, it has been proven that pesticides are also environmentally harmful substances, as they accumulate in different organisms and circulate within food, or trophic, chains. The unique chemical structures of pesticides are resistant to conventional chemical and biological degradation processes. Consequently, when plants and other living organisms treated with pesticides are consumed by animals, the toxic substances accumulate and reach high concentrations in their bodies. As larger animals eat smaller ones, these substances become more high level trophic chain. This happens both on land and in water bodies. Chemicals dissolved in rainwater and absorbed by soil particles are washed away into groundwater and then into rivers that drain agricultural land, where they begin to accumulate in fish and smaller aquatic organisms. Although some living organisms have adapted to these harmful substances, there have been cases of mass death individual species, probably due to poisoning from agricultural pesticides. For example, the insecticides rotenone and DDT and the pesticides 2,4-D and others have dealt a severe blow to the ichthyofauna. Even if the concentration of toxic chemicals is not lethal, these substances can lead to the death of animals or other harmful consequences at the next stage of the food chain. For example, gulls have died after eating large quantities of fish containing high concentrations of DDT, and several other fish-eating bird species, including the bald eagle and pelican, have been threatened with extinction due to reduced reproduction. Due to pesticides entering their body, the eggshell becomes so thin and fragile that the eggs break and the embryos of the chicks die.
Nuclear pollution. Radioactive isotopes, or radionuclides (radioactive forms of chemical elements), also accumulate within food chains because they are persistent in nature. During the process of radioactive decay, the nuclei of radioisotope atoms emit elementary particles and electromagnetic radiation. This process begins simultaneously with the formation of radioactive chemical element and continues until all its atoms are transformed under the influence of radiation into atoms of other elements. Each radioisotope is characterized by a certain half-life - the time during which the number of atoms in any of its samples is halved. Since the half-life of many radioactive isotopes is very long (eg, millions of years), their constant radiation can eventually lead to dire consequences for living organisms inhabiting bodies of water into which liquid radioactive waste is dumped. It is known that radiation destroys the tissues of plants and animals, leads to genetic mutations, infertility, and, at sufficiently high doses, death. The mechanism of the effect of radiation on living organisms has not yet been fully elucidated, and there are no effective ways mitigation or prevention negative consequences. But it is known that radiation accumulates, i.e. Repeated exposure to low doses may eventually have the same effect as a single high dose exposure.
Effect of toxic metals. Toxic metals such as mercury, arsenic, cadmium and lead also have a cumulative effect. The result of their accumulation in small doses can be the same as when receiving a single large dose. Mercury contained in industrial wastewater is deposited in bottom silt sediments in rivers and lakes. Anaerobic bacteria living in sludge convert it into toxic forms (for example, methylmercury), which can lead to serious damage to the nervous system and brain of animals and humans, as well as cause genetic mutations. Methylmercury is a volatile substance released from bottom sediments, and then, together with water, enters the body of the fish and accumulates in its tissues. Even though the fish do not die, a person who eats such contaminated fish may become poisoned and even die. Another well-known poison that enters waterways in dissolved form is arsenic. It has been found in small but measurable quantities in detergents containing water-soluble enzymes and phosphates, and in dyes intended to color cosmetic tissues and toilet paper. Lead (used in production) also enters water areas with industrial wastewater. metal products, batteries, paints, glass, gasoline and insecticides) and cadmium (used mainly in the production of batteries).
Other inorganic pollutants. In receiving basins, some metals, such as iron and manganese, are oxidized either through chemical or biological (bacterial) processes. For example, rust forms on the surface of iron and its compounds. Soluble forms of these metals exist in different types of wastewater: they have been found in water seeped from mines and scrap metal dumps, as well as from natural swamps. Salts of these metals that oxidize in water become less soluble and form solid colored precipitates that precipitate from solutions. Therefore, the water takes on color and becomes cloudy. Thus, the drains from iron ore mines and scrap metal dumps are colored red or orange-brown due to the presence of iron oxides (rust). Inorganic pollutants such as sodium chloride and sulfate, calcium chloride, etc. (i.e., salts formed during the neutralization of acidic or alkaline industrial wastewater) cannot be processed biologically or chemically. Although these substances themselves are not transformed, they affect the quality of the water into which wastewater is discharged. In many cases, it is undesirable to use “hard” water with a high salt content, since they form sediment on the walls of pipes and boilers. Inorganic substances such as zinc and copper are absorbed by the silt bottom sediments of wastewater streams and are then transported along with these fine particles by the current. Their toxic effect is stronger in an acidic environment than in a neutral or alkaline environment. In acidic coal mine wastewater, zinc, copper and aluminum reach concentrations that are lethal to aquatic life. Some pollutants, while not particularly toxic individually, become toxic compounds when interacting (for example, copper in the presence of cadmium).
CONTROL AND CLEANING
Three main methods of wastewater treatment are practiced. The first has been around for a long time and is the most economical: discharging wastewater into large watercourses, where it is diluted with fresh running water, aerated and neutralized naturally. Obviously, this method does not meet modern conditions. The second method is largely based on the same natural processes as the first, and consists of removing and reducing the content of solid and organic substances by mechanical, biological and by chemical means. It is mainly used in municipal wastewater treatment plants, which rarely have the equipment to process industrial and agricultural wastewater. The third method is widely known and quite common, which consists of reducing the volume of wastewater by changing technological processes; for example, by recycling materials or using natural pest control methods instead of pesticides, etc.
Cleaning of drains. Although many industrial enterprises are now trying to clean up their wastewater or make the production cycle closed, and the production of pesticides and other toxic substances is prohibited, the most radical and quick solution The problem of water pollution will be the construction of additional and more modern treatment facilities.
Primary (mechanical) cleaning. Typically, grates or sieves are installed along the wastewater flow path to trap floating objects and suspended particles. The sand and other coarse inorganic particles are then deposited in sand traps with sloping bottoms or captured in sieves. Oils and fats are removed from the surface of the water using special devices (oil traps, grease traps, etc.). For some time, wastewater is transferred to settling tanks to settle fine particles. Free-floating floc particles are settled by adding chemical coagulants. The sludge thus obtained, 70% consisting of organic substances, is passed through a special reinforced concrete tank - a methane tank, in which it is processed by anaerobic bacteria. As a result, liquid and gaseous methane, carbon dioxide, and mineral solid particles are formed. In the absence of a digester, solid waste is buried, dumped in landfills, burned (leading to air pollution), or dried and used as humus or fertilizer. Secondary treatment is carried out mainly by biological methods. Since the first stage does not remove organic matter, the next stage uses aerobic bacteria to decompose suspended and dissolved organic matter. The main task is to bring the wastewater into contact with as much as possible a large number bacteria in conditions of good aeration, since bacteria must be able to consume sufficient quantity dissolved oxygen. Wastewater is passed through various filters - sand, crushed stone, gravel, expanded clay or synthetic polymers (the same effect is achieved as in the process of natural purification in a riverbed stream over a distance of several kilometers). Bacteria form a film on the surface of the filter material and decompose organic wastewater as it passes through the filter, thereby reducing the BOD by more than 90%. This is the so-called bacterial filters. A 98% reduction in BOD is achieved in aeration tanks, in which natural oxidation processes are accelerated due to forced aeration of wastewater and its mixing with activated sludge. Activated sludge is formed in settling tanks from particles suspended in waste liquid, not retained during preliminary treatment and adsorbed by colloidal substances with microorganisms multiplying in them. Another method of secondary purification is long-term settling of water in special ponds or lagoons (irrigation fields or filtration fields), where algae consume carbon dioxide and release oxygen necessary for the decomposition of organic matter. In this case, BOD is reduced by 40-70%, but certain temperature conditions and solar lighting.
Tertiary treatment. Wastewater that has undergone primary and secondary treatment still contains dissolved substances that make it practically unsuitable for any use other than irrigation. Therefore, more advanced cleaning methods have been developed and tested to remove remaining contaminants. Some of these methods are used in installations that purify drinking water from reservoirs. So slowly decaying organic compounds, like pesticides and phosphates, are removed by filtration of secondary treated wastewater through activated (powdered) charcoal, or by the addition of coagulants that promote agglomeration of fine particles and sedimentation of the resulting flocs, or by treatment with such reagents that provide oxidation. Dissolved inorganic substances are removed by ion exchange (dissolved salt and metal ions); chemical precipitation (calcium and magnesium salts, which form a coating on the inner walls of boilers, tanks and pipes), softening the water; changing the osmotic pressure for enhanced filtration of water through a membrane, which retains concentrated solutions of nutrients - nitrates, phosphates, etc.; removal of nitrogen by air flow when wastewater passes through an ammonia desorption column; and other methods. There are only a few enterprises in the world that can carry out complete wastewater treatment.

The three important stages of the water cycle are evaporation (A), condensation (B), and precipitation (C). If it contains too many natural or man-made pollutants from the sources listed below, natural system does not cope with water purification. 1. Radioactive particles, dust and gases come from the atmosphere along with snow that falls and accumulates in the highlands. 2. Glacial meltwater with dissolved pollutants flows down from the highlands, forming the sources of rivers, which, on their way to the sea, carry particles of soil and rocks, eroding the surfaces along which they flow. 3. The waters draining mine workings contain acids and other inorganic substances. 4. Deforestation contributes to erosion. Many pollutants are discharged into rivers by pulp and paper mills that process wood. 5. Rainwater they wash chemicals from the soil and decomposing plants, transport them into groundwater, and also wash away soil particles from slopes into rivers. 6. Industrial gases enter the atmosphere, and from there, along with rain or snow, onto the ground. Industrial wastewater flows directly into rivers. The composition of gases and wastewater varies greatly depending on the industry sector. 7. Organic insecticides, fungicides, herbicides and fertilizers dissolved in water draining agricultural land enter rivers. 8. Spraying fields with pesticides pollutes the air and water environment. 9. Cow manure and other animal residues are the main pollutants in areas where there are large concentrations of animals in pastures and farmyards. 10. When pumping out fresh water groundwater Salinization may occur as a result of the pull-up of mineralized waters from estuaries and sea basins to their surface. 11. Methane is produced by bacteria both in natural swamps and in standing reservoirs with an excess of organic pollutants of anthropogenic origin. 12. Thermal pollution of rivers occurs due to the flow of heated water from power plants. 13. Cities generate a variety of waste, including both organic and inorganic. 14. Engine exhaust gases internal combustion- main sources of air pollution. Hydrocarbons are adsorbed by moisture in the air. 15. Large objects and particles are removed from municipal wastewater at pre-treatment stations, organic matter - at secondary treatment stations. It is impossible to get rid of many substances coming from industrial wastewater. 16. Oil spills from offshore oil wells and tankers pollute waters and beaches.

Ecological dictionary

WATER POLLUTION, contamination of water with harmful waste. Main source of water pollution industrial waste. Toxic chemicals that cannot be disinfected by CHLORINATION are discharged into industrial wastewater. The burning of fossil fuels causes... ... Scientific and technical encyclopedic dictionary

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water pollution- vandens tarša statusas Aprobuotas sritis ekologinis ūkininkavimas apibrėžtis Azoto junginių tiesioginis arba netiesioginis patekimas iš žemės ūkio šaltinių į vandenį, galintis kelti pavojų žmonių sveikatai, kenk ti gyviesiems organizmams ir… … Lithuanian dictionary (lietuvių žodynas)

water pollution- vandens tarša statusas T sritis ekologija ir aplinkotyra apibrėžtis Kenksmingųjų medžiagų (buitinių ir pramoninių nutekamųjų vandenų, žemės ūkio atliekų, transporto išmetamųjų dujų, naftos ir jos pro duktų, radioaktyviųjų medžiagų, trąšų,… … Ekologijos terminų aiškinamasis žodynas

In most cases, freshwater pollution remains invisible because the pollutants are dissolved in the water. But there are exceptions: foaming detergents, as well as oil products floating on the surface and raw sewage. There are several... ... Wikipedia

Water pollution of reservoirs and streams- The process of changing the composition and properties of water in reservoirs and streams under the influence of pollutants, microorganisms, and heat entering the water, leading to a deterioration in water quality.

Water requirements. Everyone understands how great the role of water is in the life of our planet and especially in the existence of the biosphere. Let us recall that the tissues of most plant and animal organisms contain from 50 to 90 percent water (the exception is mosses and lichens, which contain 5-7 percent water). All living organisms need a constant supply of water from outside. A person whose tissues are 65 percent water can live without drinking for only a few days (and without food he can live for more than a month). The biological need of humans and animals for water per year is 10 times greater than their own weight. Even more impressive are the domestic, industrial and agricultural needs of humans. So, to produce a ton of soap requires 2 tons of water, sugar - 9, cotton products - 200, steel 250, nitrogen fertilizers or synthetic fiber - 600, grain - about 1000, paper - 1000, synthetic rubber - 2500 tons of water.

In 1980, humanity used 3,494 cubic kilometers of water for various needs (66 percent in agriculture, 24.6 percent in industry, 5.4 percent for domestic needs, 4 percent evaporation from the surface of artificial reservoirs). This represents 9-10 percent of global river flow. During use, 64 percent of the withdrawn water evaporated, and 36 percent was returned to natural reservoirs.

In our country in 1985, 327 cubic kilometers of clean water were taken for household needs, and the volume of discharge was 150 cubic kilometers (in 1965 it was 35 cubic kilometers). In 1987, the USSR took 339 cubic kilometers for all needs fresh water(from underground sources about 10 percent), that is, approximately 1,200 tons per capita. Of the total, 38 percent went to industry, 53 to agriculture (including irrigation of dry lands), and 9 percent to drinking and household needs. In 1988, about 355-360 cubic kilometers were taken.

Water pollution. Water used by humans ultimately returns to the natural environment. But, apart from the evaporated water, this is no longer pure water, but domestic, industrial and agricultural wastewater, usually not treated or not treated sufficiently. Thus, freshwater bodies of water - rivers, lakes, land and coastal areas of the seas - are polluted. In our country, out of 150 cubic kilometers of wastewater, 40 cubic kilometers are discharged without any treatment. And modern methods of water purification, mechanical and biological, are far from perfect. According to the Institute of Biology of Inland Waters of the USSR, even after biological treatment, 10 percent of organic and 60-90 percent of inorganic substances remain in wastewater, including up to 60 percent of nitrogen. 70 phosphorus, 80 potassium and almost 100 percent salts of toxic heavy metals.

Biological pollution. There are three types of water pollution - biological, chemical and physical. Biological pollution is created by microorganisms, including pathogens, as well as organic substances capable of fermentation. The main sources of biological pollution of land waters and coastal sea waters are household wastewater, which contains feces and food waste; wastewater from food industry enterprises (slaughterhouses and meat processing plants, dairy and cheese factories, sugar factories, etc.), pulp and paper and chemical industries, and in rural areas - wastewater from large livestock complexes. Biological pollution can cause epidemics of cholera, typhoid, paratyphoid and other intestinal infections and various viral infections, such as hepatitis.

The degree of biological pollution is characterized mainly by three indicators. One of them is the number of E. coli (the so-called lactose-positive, or LPC) in a liter of water. It characterizes water contamination with animal waste products and indicates the possibility of the presence of pathogenic bacteria and viruses. According to the State Standard of 1980, for example, swimming is considered safe if the water contains no more than 1000 paints per liter. If the water contains from 5,000 to 50,000 paints per liter, then the water is considered dirty, and there is a risk of infection when swimming. If a liter of water contains more than 50,000 paints, then swimming is unacceptable. It is clear that after disinfection by chlorination or ozonation, drinking water must meet much more stringent standards.

To characterize pollution with organic substances, another indicator is used - biochemical oxygen demand (BOD). It shows how much oxygen is required for microorganisms to process all organic matter subject to decomposition into inorganic compounds (within, say, five days - then this is BOD 5. According to the standards adopted in our country, BOD 5 drinking water should not exceed 3 milligrams of oxygen per liter of water. Finally, the third indicator is the content of dissolved oxygen. It is inversely proportional to the military-industrial complex. Drinking water should contain more than 4 milligrams of dissolved oxygen per liter.

Chemical pollution is created by the entry of various toxic substances into water. The main sources of chemical pollution are blast furnace and steel production, non-ferrous metallurgy enterprises, mining, chemical industry and, to a large extent, extensive agriculture. In addition to direct discharges of wastewater into water bodies and surface runoff, it is also necessary to take into account the ingress of pollutants onto the surface of water directly from the air.

In table Figure 3 shows the rate of contamination of surface waters with toxic heavy metals (according to the same authors as the information on metal contamination of air and soil). These data include 30 percent of the mass of metals entering the atmospheric air.

As in air pollution, in the pollution of surface waters (and, looking ahead a little, ocean waters), among heavy metals, lead holds the palm: its ratio of artificial to natural sources exceeds 17. Other heavy metals include copper, zinc, chromium, nickel , the artificial source of cadmium entering natural waters is also greater than natural, but not as much as that of lead. A major danger is posed by mercury pollution that enters natural waters from the air, forests and fields treated with pesticides, and sometimes as a result of industrial discharges. Water runoff from mercury deposits or mines, where mercury can become soluble compounds, is extremely dangerous. This threat makes reservoir projects on the Altai Katun River extremely dangerous.

In recent years, the flow of nitrates into land surface waters has increased significantly due to the irrational use of nitrogen fertilizers, as well as due to increased emissions into the atmosphere from vehicle exhaust gases. The same applies to phosphates, for which, in addition to fertilizers, the source is the increasingly widespread use of various detergents. Dangerous chemical pollution is created by hydrocarbons - oil and its refined products, which enter rivers and lakes both with industrial discharges, especially during oil production and transportation, and as a result of being washed off from the soil and falling out of the atmosphere.

Wastewater dilution. To make wastewater more or less suitable for use, it is subjected to repeated dilution. But it would be more correct to say that in this case, clean natural waters, which could be used for any purpose, including drinking, become less suitable for this and become polluted. So, if dilution by 30 times is considered mandatory, then, for example, to dilute 20 cubic kilometers of wastewater discharged into the Volga, 600 cubic kilometers of clean water would be needed, which is more than twice the annual flow of this river (250 cubic kilometers). To dilute all the waste discharged into rivers in our country, 4,500 cubic kilometers of clean water would be required, that is, almost the entire river flow in the USSR, amounting to 4.7 thousand cubic kilometers. This means that there are almost no clean surface waters left in our country.

Wastewater dilution reduces the quality of water in natural bodies of water, but usually does not achieve its intended purpose. main goal- preventing harm to human health. The fact is that harmful impurities contained in water in negligible concentrations accumulate in some organisms that people eat. First, toxic substances enter the tissues of the smallest planktonic organisms, then they accumulate in organisms that filter through the process of breathing and feeding a large number of water (molluscs, sponges, etc.) and ultimately, both through the food chain and during respiration, are concentrated in the tissues of fish. As a result, the concentration of poisons in fish tissues can become hundreds and even thousands of times greater than in water.

In 1956, an epidemic of an unknown disease with complete breakdown of the central nervous system broke out in Minamata (Kyushu Island, Japan). People's vision and hearing deteriorated, speech was impaired, their minds were lost, movements became uncertain, accompanied by trembling. Minamata disease affected several hundred people, with 43 deaths reported. It turned out that the culprit was a chemical plant on the shore of the bay. Careful studies, which the plant administration initially put up with all sorts of obstacles, showed that its wastewater contains mercury salts, which are used as catalysts in the production of acetaldehyde. Mercury salts themselves are poisonous, and under the influence of specific microorganisms in the bay they turned into extremely toxic methylmercury, which was concentrated in fish tissues 500 thousand times. People were poisoned by this fish.

Dilution of industrial wastewater, and especially solutions of fertilizers and pesticides from agricultural fields, often occurs in natural reservoirs themselves. If the reservoir is stagnant or weakly flowing, then the discharge of organic matter and fertilizers into it leads to an excess of nutrients - eutrophication and overgrowing of the reservoir. First, in such a reservoir they accumulate nutrients and algae, mainly microscopic blue-green, grow rapidly. After they die, the biomass sinks to the bottom, where it mineralizes and consumes large amounts of oxygen. Conditions in the deep layer of such a reservoir become unsuitable for the life of fish and other organisms that require oxygen. When all the oxygen is exhausted, oxygen-free fermentation begins with the release of methane and hydrogen sulfide. Then the entire reservoir is poisoned and all living organisms die (except for some bacteria). Such an unenviable fate threatens not only lakes into which household and industrial wastewater is discharged, but also some closed and semi-enclosed seas.

Damage to water bodies, especially rivers, is caused not only by an increase in the volume of discharged pollution, but also by a decrease in the ability of water bodies to self-purify. A striking example of this is the current state of the Volga, which is more of a cascade of low-flow reservoirs than a river in the original sense of the word. The damage is obvious: the acceleration of pollution, the death of aquatic organisms in places of water intake, the disruption of usual migration movements, the loss of valuable agricultural land, and much more. Is this damage compensated by the energy produced at hydroelectric power plants? The pros and cons must be re-calculated taking into account the modern environmental requirements of human existence. And it may turn out that it is more expedient to dismantle some dams and liquidate reservoirs than to suffer losses from year to year.

Physical pollution water is created by dumping heat or radioactive substances into it. Thermal pollution is mainly due to the fact that the water used for cooling at thermal and nuclear power plants (and, accordingly, about 1/3 and 1/2 of the energy generated) is discharged into the same body of water. Some industrial enterprises also contribute to thermal pollution. Since the beginning of this century, the water in the Seine has warmed by more than 5°, and many rivers in France have stopped freezing in winter. On the Moskva River within Moscow, it is now rarely possible to see ice floes in winter, and recently, at the confluence of some rivers (for example, Setun) and discharges of thermal power plants, ice holes with ducks wintering on them were observed. On some rivers in the industrial east of the United States, back in the late 60s, the water heated up to 38˚ and even 48˚ in the summer.

With significant thermal pollution, the fish suffocate and die, as its need for oxygen increases and the solubility of oxygen decreases. The amount of oxygen in water also decreases because, with thermal pollution, rapid development of unicellular algae occurs: the water “blooms,” followed by rotting of the dying plant mass. In addition, thermal pollution significantly increases the toxicity of many chemical pollutants, in particular heavy metals.

During normal operation of nuclear reactors, neutrons can enter the coolant, which is mainly water, under the influence of which the atoms of this substance and impurities, primarily corrosion products, become radioactive. In addition, the protective zirconium shells of fuel elements may have microcracks through which nuclear reaction products can enter the coolant. Although such waste is low-level, it can still increase the overall background radioactivity. In case of accidents, the waste may become more active. In natural bodies of water, radioactive substances undergo physicochemical transformations - concentration on suspended particles (adsorption, including ion exchange), precipitation, sedimentation, transfer by currents, absorption by living organisms, accumulation in their tissues. In living organisms, primarily radioactive mercury, phosphorus, and cadmium accumulate, in the soil - vanadium, cesium, niobium, zinc, and sulfur, chromium, and iodine remain in the water.

Pollution oceans and seas occurs as a result of the entry of pollutants with river runoff, their fall out from the atmosphere and, finally, due to human economic activity directly in the seas and oceans. According to data dating back to the first half of the 1980s, even in a sea like the North Sea, where the Rhine and Elbe flow, collecting runoff from the vast industrial zone of Europe, the amount of lead brought by rivers is only 31 percent of the total, while in atmospheric source accounts for 58 percent. the rest falls on industrial and domestic wastewater from the coastal zone.

With river flow, the volume of which is about 36-38 thousand cubic kilometers, a huge amount of pollutants in suspended and dissolved form enters the oceans and seas. According to some estimates, more than 320 million tons of iron, up to 200 thousand tons of lead, 110 million tons of sulfur, up to 20 thousand tons of cadmium, from 5 to 8 thousand tons of mercury, 6.5 million tons of phosphorus, hundreds of millions of tons of organic pollutants. This is especially true for inland and semi-enclosed seas, where the ratio of the drainage area to the sea itself is greater than that of the entire World Ocean (for example, near the Black Sea it is 4.4 versus 0.4 near the World Ocean). According to minimal estimates, 367 thousand tons of organic matter, 45 thousand tons of nitrogen, 20 thousand tons of phosphorus, and 13 thousand tons of petroleum products enter the Caspian Sea with the flow of the Volga. There is a high content of organochlorine pesticides in the tissues of sturgeon and sprat, the main fish species. In the Sea of ​​Azov from 1983 to 1987, the content of pesticides increased more than 5 times. In the Baltic Sea over the past 40 years, the content of cadmium has increased by 2.4 percent, mercury by 4 percent, and lead by 9 percent.

Pollution arriving with river runoff is distributed unevenly across the ocean. About 80 to 95 percent of the suspended matter and 20 to 60 percent of the dissolved matter in river runoff is lost in river deltas and estuaries and does not reach the ocean. That part of the pollution that does break through the areas of “avalanche deposition” at river mouths moves mainly along the coast, remaining within the shelf. Therefore, the role of river runoff in polluting the open ocean is not as great as previously thought.

Atmospheric sources of ocean pollution are comparable to river runoff for some types of pollutants. This applies, for example, to lead, the average concentration of which in the waters of the North Atlantic has increased over forty-five years from 0.01 to 0.07 milligrams per liter and decreases with depth, directly pointing to an atmospheric source. Almost the same amount of mercury comes from the atmosphere as from river runoff. Half of the pesticides found in ocean waters also come from the atmosphere. Somewhat less than with river runoff, cadmium, sulfur, and hydrocarbons enter the ocean from the atmosphere.

Oil pollution. A special place is occupied by ocean pollution with oil and petroleum products. Natural pollution occurs as a result of oil seepage from oil-bearing layers, mainly on the shelf. For example, in the Santa Barbara Channel off the coast of California (USA), an average of almost 3 thousand tons per year arrives this way; this seepage was discovered back in 1793 by the English navigator George Vancouver. In total, from 0.2 to 2 million tons of oil per year enter the World Ocean from natural sources. If we take the lower estimate, which seems more reliable, it turns out that the artificial source, which is estimated at 5-10 million tons per year, exceeds the natural one by 25-50 times.

About half of artificial sources are created by human activity directly on the seas and oceans. In second place is river runoff (together with surface runoff from the coastal area) and in third place is the atmospheric source. Soviet specialists M. Nesterova, A. Simonov, I. Nemirovskaya give the following ratio between these sources - 46:44:10.

The largest contribution to ocean oil pollution is made by seaborne oil transportation. Of the 3 billion tons of oil currently produced, about 2 billion tons are transported by sea. Even with accident-free transport, oil losses occur during loading and unloading, the discharge of washing and ballast water into the ocean (with which tanks are filled after unloading oil), as well as during the discharge of so-called bilge water, which always accumulates on the floor of the engine rooms of any ships. Although international conventions prohibit the discharge of oil-contaminated waters in special areas of the ocean (such as the Mediterranean, Black, Baltic, Red Seas, and the Persian Gulf), in the immediate vicinity of the coast in any area of ​​the ocean, they impose restrictions on the content of oil and oil products in discharged waters, they still do not eliminate pollution; During loading and unloading, oil spills occur as a result of human errors or equipment failure.

But the greatest damage to the environment and the biosphere is caused by sudden spills of large quantities of oil during tanker accidents, although such spills account for only 5-6 percent of total oil pollution. The chronicle of these accidents is as long as the history of the maritime transportation of oil itself. The first such accident is believed to have occurred on Friday 13 December 1907, when the 1,200 ton seven-masted sailing schooner Thomas Lawson, carrying a cargo of kerosene, crashed into rocks off the Isles of Scilly, off the south-western tip of Great Britain, in stormy weather. The cause of the accident was bad weather, which for a long time did not allow astronomical determination of the ship's location, as a result of which it deviated from course, and a severe storm that tore the schooner from its anchors and threw it onto the rocks. As a curiosity, we note that the most popular book by the writer Thomas Lawson, whose name the lost schooner bore, was called “Friday the 13th.”

On the night of March 25, 1989, the American tanker Exxon Valdie, which had just departed from the oil pipeline terminal in the port of Valdez (Alaska) with a cargo of 177,400 tons of crude oil, while passing through Prince William Sound, ran into an underwater rock and ran aground. Eight holes in its hull spilled more than 40 thousand tons of oil, which within a few hours formed a slick with an area of ​​more than 100 square kilometers. Thousands of birds floundered in the oil lake, thousands of fish surfaced, and mammals died. Subsequently, the spot, expanding, drifted to the southwest, polluting the adjacent shores. Enormous damage was caused to the flora and fauna of the area, many local species were in danger of complete extinction. Six months later, the Exxon oil company, having spent $1,400 million, stopped work to eliminate the consequences of the disaster, although the complete restoration of the ecological health of the area was still very far away. The cause of the accident was the irresponsibility of the ship's captain, who, while drunk, entrusted the control of the tanker to an unauthorized person. The inexperienced third officer, frightened by the ice floes that appeared nearby, mistakenly changed course, resulting in a disaster.

Between these two events, at least a thousand oil tankers were lost, and there were many more accidents in which the ship was saved. The number of accidents increased and their consequences became more serious as the volume of maritime transport of oil increased. In 1969 and 1970, for example, there were 700 accidents of various sizes, as a result of which more than 200 thousand tons of oil ended up in the sea. The causes of accidents are varied: navigation errors, bad weather, technical problems, and irresponsible personnel. The desire to reduce the cost of oil transportation has led to the appearance of supertankers with a displacement of more than 200 thousand tons. In 1966, the first such vessel was built - the Japanese tanker Idemitsu Maru (206 thousand tons), then tankers of even larger displacement appeared: Universe Ireland (326 thousand deadweight tons): Nisseki Maru ( 372 thousand tons); “Globtik Tokyo” and “Globtik London” (478 thousand tons each); “Batillus” (540 thousand tons): “Pierre Guillaume” (550 thousand tons), etc. Per ton of cargo capacity, this really reduced the cost of building and operating the vessel, so it became more profitable to transport oil from the Persian Gulf to Europe, rounding the southern the tip of Africa, rather than by conventional tankers along the shortest route - through the Suez Canal (previously, such a route was forced due to the Israeli-Arab war). However, as a result, another cause of oil spills has emerged: supertankers have become quite often broken up by very large ocean waves, which can be as long as the tankers.

The hull of supertankers may not be able to withstand it if its middle part ends up on the crest of such a wave, and the bow and stern hang over the soles. Such accidents were noted not only in the area of ​​​​the famous “key rollers” off South Africa, where waves, accelerated by the westerly winds of the “Roaring Forties,” enter the oncoming current of Cape Agulhas, but also in other areas of the ocean.

The disaster of the century today remains the accident that occurred with the supertanker “Amoco Cadiz”, which in the area of ​​the island of Ouessant (Brittany, France) lost control due to malfunctions of the steering mechanism (and the time it took to negotiate with the rescue vessel) and sat on the rocks near of this island. This happened on March 16, 1978. All 223 thousand tons of crude oil spilled from the Amoco Cadiz tanks into the sea. This created a severe environmental disaster in a vast area of ​​the sea adjacent to Brittany and along a large stretch of its coast. Already in the first two weeks after the disaster, the spilled oil spread over a vast area of ​​water, and the French coastline was polluted for 300 kilometers. Within a few kilometers from the site of the accident (and it happened 1.5 miles from the coast), all living things died: birds, fish, crustaceans, mollusks, and other organisms. According to scientists, biological damage has never been seen over such a huge area in any of the previous oil pollution events. A month after the spill, 67 thousand tons of oil had evaporated, 62 thousand had reached the shore, 30 thousand tons had been distributed in the water column (of which 10 thousand tons had decomposed under the influence of microorganisms), 18 thousand tons had been absorbed by sediments in shallow waters, and 46 thousand tons had been collected from shore and from the surface of the water mechanically.

The main physicochemical and biological processes through which self-purification of ocean waters occur are dissolution, biological decomposition, emulsification, evaporation, photochemical oxidation, agglomeration and sedimentation. But even three years after the accident of the Amoco Cadiz tanker, oil residues remained in the bottom sediments of the coastal zone. 5-7 years after the disaster, the content of aromatic hydrocarbons in bottom sediments remained 100-200 times higher than normal. According to scientists, it will take many years to restore the full ecological balance of the natural environment.

Accidental spills occur during offshore oil production, which currently accounts for about a third of all global production. On average, such accidents make a relatively small contribution to oil pollution of the ocean, but individual accidents are catastrophic. These include, for example, the accident at the Ixtoc-1 drilling rig in the Gulf of Mexico in June 1979. The out-of-control oil gusher erupted for more than six months. During this time, almost 500 thousand tons of oil ended up in the sea (according to other sources, almost a million tons). The time of self-cleaning and damage to the biosphere during oil spills are closely related to climatic and weather conditions, and the prevailing water circulation. Despite the huge amount of oil spilled during the accident on the Ixtoc-1 platform, which stretched in a wide strip for a thousand kilometers from the Mexican coast to Texas (USA), only a small share of it reached the coastal zone. In addition, the prevalence of stormy weather contributed to the rapid dilution of oil. Therefore, this spill did not have such noticeable consequences as the Amoco Cadiz disaster. On the other hand, if it took at least 10 years to restore the ecological balance in the “catastrophe of the century” zone, then, according to scientists’ forecasts, it will take about 5 to 15 years, although the amount of oil spilled there is 5 times less. The fact is that low water temperatures slow down the evaporation of oil from the surface and significantly reduce the activity of oil-oxidizing bacteria, which ultimately destroy oil pollution. In addition, the heavily rugged rocky shores of Prince William Sound and the islands located in it form numerous “pockets” of oil that will serve as long-term sources of pollution, and the oil there contains a large percentage of the heavy fraction, which decomposes much more slowly than light oil.

Thanks to the action of wind and currents, oil pollution has affected essentially the entire oceans. At the same time, the degree of ocean pollution is increasing from year to year.

In the open ocean, oil occurs visually as a thin film (with minimum thickness up to 0.15 micrometers) and resin lumps, which are formed from heavy fractions of oil. If tar lumps primarily affect plant and animal marine organisms, then the oil film, in addition, affects many physical and chemical processes occurring at the ocean-atmosphere interface and in the layers adjacent to it. With increasing ocean pollution, this impact may become global.

First of all, the oil film increases the share of solar energy reflected from the ocean surface and reduces the share of absorbed energy. Thus, the oil film influences the processes of heat accumulation in the ocean. Despite the decrease in the amount of incoming heat, the surface temperature in the presence of an oil film increases the more, the thicker the oil film. The ocean is the main supplier of atmospheric moisture, on which the degree of continental humidification largely depends. The oil film makes it difficult for moisture to evaporate, and with a sufficiently large thickness (about 400 micrometers) it can reduce it to almost zero. By smoothing out wind waves and preventing the formation of water spray, which, when evaporating, leaves tiny particles of salt in the atmosphere, the oil film changes the salt exchange between the ocean and the atmosphere. This can also affect the amount of precipitation over the ocean and continents, since salt particles make up a large part of the condensation nuclei needed to form rain.

Hazardous waste. According to the United Nations International Commission on Environment and Development, the amount of hazardous waste generated annually in the world is more than 300 million tons, with 90 percent of it occurring in industrialized countries. There was a time, not too distant, when hazardous waste from chemical and other enterprises ended up in ordinary city landfills, dumped in water bodies, and buried in the ground without taking any precautions. However, soon, in one country or another, the sometimes very tragic consequences of frivolous handling of hazardous waste began to appear more and more often. A broad environmental public movement in industrialized countries has forced the governments of these countries to significantly tighten legislation on the disposal of hazardous waste.

In recent years, hazardous waste problems have become truly global. Hazardous wastes have increasingly crossed national borders, sometimes without the knowledge of the government or public of the receiving country. Underdeveloped countries especially suffer from this type of trade. Some publicized egregious cases literally shocked the world community. On June 2, 1988, about 4 thousand tons of toxic waste of foreign origin were discovered in the area of ​​​​the small town of Koko (Nigeria). The cargo was imported from Italy in five shipments from August 1987 to May 1988 using forged documents. The Nigerian government arrested the culprits, as well as the Italian merchant ship Piave, in order to ship the hazardous waste back to Italy. Nigeria recalled its ambassador from Italy and threatened to take the case to the international court in The Hague. A survey of the landfill revealed that the metal drums contained volatile solvents and were at risk of fire or explosion, producing extremely toxic fumes. About 4,000 barrels were old, rusty, many were swollen from the heat, and three of them contained a highly radioactive substance. When loading waste for shipment to Italy on the ship “Karin B”, which became notorious, loaders and crew members were injured. Some of them received severe chemical burns, others suffered from vomiting blood, and one person was partially paralyzed. By mid-August, the landfill was cleared of foreign “gifts.”

In March of that year, 15,000 tons of “raw brick material” (so the documents said) were buried in a quarry on the island of Kassa opposite Conakry, the capital of Guinea. Under the same contract, another 70 thousand tons of the same cargo were soon to be delivered. After 3 months, newspapers reported that the vegetation on the island was drying out and dying. It turned out that the cargo delivered by the Norwegian company was ash rich in toxic heavy metals from household waste incinerators from Philadelphia (USA). The Norwegian consul, who turned out to be the director of the Norwegian-Guinean company - the direct culprit of the incident, was arrested. The waste was removed.

Even a complete list of cases known today will not be exhaustive, since, of course, not all cases are made public. On March 22, 1989, in Basel (Switzerland), representatives of 105 countries signed a treaty to control the export of toxic waste, which will come into force after ratification by at least 20 countries. The highlight of this agreement is considered to be an indispensable condition: the government of the receiving country must give written permission in advance to accept waste. The treaty thus excludes fraudulent transactions but legitimizes transactions between governments. The Green environmental movement has condemned the treaty and is demanding a complete ban on the export of hazardous waste. The effectiveness of the measures taken by the “greens” is evidenced by the fate of some ships that carelessly took on board dangerous cargo. The already mentioned “Karin B” and “Deep Sea Carrier”, which were transporting dangerous cargo from Nigeria, could not immediately unload; the ship that left Philadelphia in August 1986 with 10 thousand tons of waste wandered the seas for a long time, the cargo of which was not accepted in the Bahamas , nor in Honduras, Haiti, Dominican Republic, Guinea-Bissau. The dangerous cargo, containing cyanide, pesticides, dioxin and other poisons, traveled for more than a year before returning on board the Syrian ship Zanoobia to the port of departure Marina de Carrara (Italy).

The problem of hazardous waste must, of course, be solved by creating waste-free technologies and decomposing waste into harmless compounds, for example, using high-temperature combustion.

Radioactive waste. The problem of radioactive waste is of particular importance. Their distinctive feature is the impossibility of their destruction and the need to isolate them from the environment for a long time. As mentioned above, the bulk of radioactive waste is generated at nuclear industry plants. These wastes, mostly solid and liquid, are highly radioactive mixtures of uranium fission products and transuranic elements (except plutonium, which is separated from the waste and used in the military industry and for other purposes). The radioactivity of the mixture averages 1.2-10 5 Curie per kilogram, which approximately corresponds to the activity of strontium-90 and cesium-137. Currently, there are about 400 nuclear reactors operating in the world at nuclear power plants with a capacity of about 275 gigawatts. Roughly, we can assume that per 1 gigawatt of power annually there is about a ton of radioactive waste with an average activity of 1.2-10 5 Curies. Thus, the amount of waste by weight is relatively small, but its total activity is growing rapidly. So, in 1970 it was 5.55-10 20 Becquerels, in 1980 it quadrupled, and in 2000, according to forecasts, it will quadruple. The problem of disposal of such waste has not yet been resolved.

A large surface of the Earth is covered with water, which altogether makes up the World Ocean. On land there are sources of fresh water - lakes. Rivers are the vital arteries of many cities and countries. The seas feed a large number of people. All this suggests that there cannot be life on the planet without water. However, people neglect the main resource of nature, which has led to enormous pollution of the hydrosphere.

Water is necessary for life not only for people, but for animals and plants. By wasting water and polluting it, all life on the planet is at risk. Water supplies on the planet vary. Some parts of the world have a sufficient number of bodies of water, while others experience great water shortages. Moreover, 3 million people die every year from diseases caused by drinking poor quality water.

Causes of water pollution

Since surface waters are the source of water for many populated areas, the main cause of pollution of water bodies is anthropogenic activity. The main sources of hydrosphere pollution:

• domestic wastewater;
• operation of hydroelectric power stations;
• dams and reservoirs;
• use of agrochemicals;
• biological organisms;
• industrial water runoff;
• radiation pollution.

Of course, this list can be continued indefinitely. Quite often, water resources are used for some purpose, but by discharging wastewater into the water, it is not even cleaned, and the polluting elements spread their range and deepen the situation.

Protection of water bodies from pollution

The condition of many rivers and lakes around the world is critical. If you do not stop the pollution of water bodies, then many aquatic systems will stop functioning - self-cleaning and giving life to fish and other inhabitants. Including people will not have any water reserves, which will inevitably lead to death.

Before it’s too late, reservoirs need to be protected. It is important to control the process of water discharge and the interaction of industrial enterprises with water bodies. It is necessary for every person to save water resources, since excessive water consumption contributes to the use of more of it, which means that water bodies will become more polluted. Protection of rivers and lakes, control of resource use is necessary measure in order to preserve the planet’s reserves of clean drinking water, necessary for life for everyone without exception. In addition, it requires a more rational distribution water resources between different localities and entire states.

Pollution of water bodies– discharge or otherwise entering water bodies (surface and underground), as well as the formation in them of harmful substances that worsen the quality of water, limit their use or negatively affect the condition of the bottom and banks of water bodies; anthropogenic introduction of various pollutants into the aquatic ecosystem, the impact of which on living organisms exceeds the natural level, causing their oppression, degradation and death.

There are several types of water pollution:

The most dangerous at present seems to be chemical water pollution due to on a global scale manifestations of this process, an increase in the number of pollutants, among which there are many xenobiotics, i.e. substances alien to aquatic and semi-aquatic ecosystems.

Pollutants enter the environment in liquid, solid, gaseous and aerosol form. The routes of their entry into the aquatic environment are varied: directly into water bodies, through the atmosphere with precipitation and during dry deposition, through the drainage area with surface, intrasoil and underground water flow.

Sources of pollutants can be divided into concentrated, distributed, or diffuse, and linear.

Concentrated runoff comes from enterprises and utilities and, as a rule, is controlled in volume and composition by the relevant services and can be managed, in particular through the construction of treatment facilities. Diffuse runoff comes irregularly from built-up areas, unequipped landfills and landfills, agricultural fields and livestock farms, as well as from precipitation. This runoff is generally unmonitored and unregulated.

Sources of diffuse runoff are also zones of anomalous technogenic soil pollution, which systematically “feed” water bodies with hazardous substances. Such zones were formed, for example, after the Chernobyl accident. These are also lenses of liquid waste, for example, petroleum products, solid waste burial sites, the waterproofing of which is broken.

It is almost impossible to control the flow of pollutants from such sources; the only way is to prevent their formation.

Global pollution is a sign of today. Natural and man-made flows of chemicals are comparable in scale; For some substances (primarily metals), the intensity of anthropogenic turnover is many times greater than the intensity of the natural cycle.

Acid precipitation, formed as a result of nitrogen and sulfur oxides entering the atmosphere, significantly changes the behavior of microelements in water bodies and their catchment areas. The process of removal of microelements from soils is activated, water acidification occurs in reservoirs, which negatively affects all aquatic ecosystems.

An important consequence of water pollution is the accumulation of pollutants in the bottom sediments of water bodies. Under certain conditions, they are released into the water mass, causing an increase in pollution in the apparent absence of pollution from wastewater.

Dangerous water pollutants include oil and petroleum products. Their sources are all stages of oil production, transportation and refining, as well as consumption of petroleum products. In Russia, tens of thousands of medium and large accidental oil and petroleum product spills occur annually. A lot of oil gets into the water due to leaks in oil and product pipelines, railways, on the territory of oil storage facilities. Natural oil is a mixture of dozens of individual hydrocarbons, some of which are toxic. It also contains heavy metals (for example molybdenum and vanadium), radionuclides (uranium and thorium).

The main process of transformation of hydrocarbons into natural environment is biodegradation. However, its speed is low and depends on the hydrometeorological situation. In the northern regions, where the main Russian oil reserves are concentrated, the rate of oil biodegradation is very low. Some of the oil and insufficiently oxidized hydrocarbons fall to the bottom of water bodies, where the rate of their oxidation is practically zero. Substances such as polyaromatic hydrocarbons of petroleum, including 3,4-benzo(a)pyrene, exhibit increased stability in water. An increase in its concentration poses a real danger to the organisms of the aquatic ecosystem.

Another dangerous component of water pollution is pesticides. Migrating in the form of suspensions, they settle to the bottom of water bodies. Bottom sediments are the main reservoir for the accumulation of pesticides and other persistent organic pollutants, which ensures their long-term circulation in aquatic ecosystems. In food chains their concentration increases many times over. Thus, compared to the content in bottom silt, the concentration of DDT in algae increases 10 times, in zooplankton (crustaceans) - 100 times, in fish - 1000 times, in predatory fish - 10,000 times.

A number of pesticides have structures unknown to nature and therefore resistant to biotransformation. These pesticides include organochlorine pesticides, which are extremely toxic and persistent in the aquatic environment and in soils. Representatives such as DDT are banned, but traces of this substance are still found in nature.

Persistent substances include dioxins and polychlorinated biphenyls. Some of them have exceptional toxicity that surpasses the most powerful poisons. For example, the maximum permissible concentration of dioxins in surface and groundwater in the USA is 0.013 ng/l, in Germany - 0.01 ng/l. They actively accumulate in food chains, especially in the final links of these chains - in animals. The highest concentrations are observed in fish.

Polyaromatic hydrocarbons (PAHs) enter the environment with energy and transport waste. Among them, benzo(a)pyrene accounts for 70–80% of the emission mass. PAHs are classified as strong carcinogens.

Surfactants (surfactants) are usually not toxic, but they form a film on the surface of the water that disrupts gas exchange between water and the atmosphere. Phosphates included in surfactants cause eutrophication of water bodies.

Use of mineral and organic fertilizers leads to contamination of soils, surface and groundwater with compounds of nitrogen, phosphorus, and microelements. Pollution with phosphorus compounds is the main cause of eutrophication of water bodies; the greatest threat to the biota of water bodies is posed by blue-green algae, or cyanobacteria, which multiply in huge quantities during the warm season in water bodies prone to eutrophication. When these organisms die and decompose, acutely toxic substances – cyanotoxins – are released. About 20% of all phosphorus pollution in water bodies comes from agricultural landscapes, 45% comes from livestock farming and municipal wastewater, and more than a third comes from losses during transportation and storage of fertilizers.

IN mineral fertilizers contains a large “bouquet” of microelements. Among them are heavy metals: chromium, lead, zinc, copper, arsenic, cadmium, nickel. They can negatively affect animals and humans.

The huge number of existing anthropogenic sources of pollution and the numerous ways in which pollutants enter water bodies make it practically impossible to completely eliminate pollution of water bodies. Therefore, it was necessary to determine water quality indicators that ensure the safety of water use by the population and the stability of aquatic ecosystems. The establishment of such indicators is called water quality standardization. In sanitary and hygienic standards, the focus is on the impact of dangerous concentrations of chemicals in water on human health, while in environmental standards, the priority is to ensure the protection of living organisms in the aquatic environment from them.

The indicator of maximum permissible concentrations (MAC) is based on the concept of the threshold of action of a pollutant. Below this threshold, the concentration of the substance is considered safe for organisms.

The classification of water bodies according to the nature and level of pollution allows for a classification that establishes four degrees of pollution of a water body: permissible (1-fold excess of MPC), moderate (3-fold excess of MPC), high (10-fold excess of MPC) and extremely high (100 - multiple excess of MPC).

Environmental regulation is designed to ensure the preservation of the sustainability and integrity of aquatic ecosystems. Using the principle of the “weak link” of an ecosystem allows us to estimate the concentration of pollutants that are acceptable for the most vulnerable component of the system. This concentration is accepted as acceptable for the entire ecosystem as a whole.

The degree of pollution of land waters is controlled by the State Monitoring of Water Bodies system. In 2007, sampling for physical and chemical indicators with the simultaneous determination of hydrological indicators was carried out at 1716 points (2390 sections).

IN Russian Federation The problem of providing the population with good-quality drinking water remains unresolved. The main reason for this is the unsatisfactory condition of water supply sources. Rivers like

Pollution of aquatic ecosystems leads to a decrease in biodiversity and depletion of the gene pool. This is not the only, but important reason for the decline in biodiversity and numbers of aquatic species.

Protecting natural resources and ensuring the quality of natural waters is a task of national importance.

By Order of the Government of the Russian Federation of August 27, 2009 No. 1235-r, the Water Strategy of the Russian Federation for the period until 2020 was approved. It states that in order to improve the quality of water in water bodies, restore aquatic ecosystems and the recreational potential of water bodies, the following tasks must be solved:

To solve this problem, legislative, organizational, economic, technological measures are required, and most importantly, political will aimed at solving the formulated problems.