Drinking water contamination. Water pollution
WATER POLLUTION
changes in the chemical and physical state or biological characteristics of water, limiting its further use. For all types of water use, either physical condition(for example, when heated), or the chemical composition of 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 textile industry, and inactive organic matter type of 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. Cities' 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. At reuse Insufficiently treated fecal waste, the bacteria and viruses it contains can cause intestinal diseases (typhoid, cholera and dysentery), as well as hepatitis and polio. Dissolved in waste water ah there are soap, synthetic washing powders, disinfectants, bleaches and other household chemicals. 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 does different functions, for example, serves as a raw material, heater and cooler in technological processes, in addition, transports, sorts and washes various 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 inorganic substances are discharged with industrial wastewater. 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 residues chemicals, contributing to increased 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, a large volume of feces and other organic residues from farms where large meat and dairy products are grown cattle, pigs or poultry. A lot of organic waste also comes from the processing of agricultural products (during the cutting of meat carcasses, leather processing, production 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 the water and release carbon dioxide as the organic residues are digested. 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 food industry enterprises, paper fibers and cellulose residues from pulp and paper industry enterprises, the decomposition processes proceed almost identically. Since aerobic bacteria use oxygen, the first result of the breakdown of organic residues is a decrease in the amount of oxygen 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 for the design of municipal wastewater treatment plants, the decomposition of organic substances contained in one liter of municipal wastewater of normal composition at a temperature of 20 ° C requires approximately 200 mg of oxygen 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 streams with fast current, 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 acid, to coal mine drainage water also significantly reduces the ability of some fish species to extract oxygen from the 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. The 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 the saturation of pathogenic microorganisms or floated 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 decay 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. Under 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 water look like pea soup with a foul odor and fishy taste, and also cover the stones with 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, accelerates the rate of chemical reactions and, therefore, affects the life of animals and plants in water intake basins. There are vivid examples of 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 malaria 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 mass death certain species, probably due to poisoning by 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 detrimental effects 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 the pesticides that enter their body, the eggshell becomes so thin and fragile that the eggs break and the embryos of the chicks die.
Radioactive contamination. 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 if sufficiently high doses- to death. The mechanism of the effects of radiation on living organisms is still not fully understood, and there are no effective ways to mitigate or prevent 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 dose 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 can 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 dyes intended for coloring cosmetic wipes and toilet paper. Lead (used in the production of 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 Sewage: They have been found in water leaking 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 waters 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 based largely on the same natural processes as the first and involves removing and reducing solids and organic matter by mechanical, biological and 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, consisting in reducing the volume of wastewater by changing technological processes; for example, as a result recycling materials or using natural pest control methods instead of pesticides, etc.
Wastewater treatment. 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 quickest solution to 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 under conditions of good aeration, since the bacteria must be able to consume a sufficient amount of 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 matter in the 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. Slowly decomposing organic compounds such as pesticides and phosphates are removed by filtering the treated wastewater through activated (powdered) charcoal, or by adding coagulants to 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 there are too many natural or man-made pollutants from the sources listed below, the natural system will not be able to clean the water. 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 soil particles 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 dung and other animal residues are the main pollutants in areas with large concentrations of animals in pastures and barnyards. 10. When fresh groundwater is pumped out, salinization may occur as a result of the pull-up of mineralized water 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. Exhaust gases from internal combustion engines are the 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
water pollution- Pollution of rivers, lakes, seas, groundwater with substances not usually present in them, which make the water unsuitable for use. Syn.: water pollution… Dictionary of Geography
water pollution- — EN water pollution The manmade or man induced alteration of the chemical, physical, biological and radiological integrity of water. (Source: LANDY)… … Technical Translator's Guide
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, kti 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 produktų, 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.
According to WWF, the list of the most polluted rivers in the world includes at the moment include Asian, European, American, Australian water flows. What rivers should you not swim in under any circumstances?
Dirty rivers of the world
Every continent now has its own “dead” river. Most often these are large rivers with a densely populated basin. It's scary to think how quickly a person transforms environment, and how several decades of demographic and industrial growth thoughtlessly erase entire eras of development of the fragile biosphere.So, let's start with Asia and its leader in water pollution - the Ganges River. More than 500 million people live and litter in the basin of this sacred Indian river. Overpopulated cities with low level life and numerous industrial enterprises dump millions of tons of waste and sewage into the water every day. The Ganga Action Plan, the Indian government's plan to clean up the river by the year 2000, became obsolete even before it was implemented due to the steady increase in discharge volumes. Near major cities, the river is a hellish cocktail of chemicals and feces.
The sacred river Ganges is one of the dirtiest in the world
However, every year about 700 million people travel to the Ganges religious ceremonies. People wash themselves, scatter the ashes, and dump the corpses of the dead. And every year millions of those who bathe in sacred waters die from infectious diseases, mostly children suffer.
According to analyses, the bacteria content in the Ganges water near major cities is 120 times higher than the officially permissible limit.
One of the branches of the Ganges in Bangladesh, the Buriganga River, is officially declared dead, unsuitable for any human use at all. True, this does not prevent local residents from continuing to fish in it, wash clothes and... also die.
Let's proceed further to the East. China, Yellow River. The famous Yellow River is quite dirty in appearance due to its high content of colored silt. But this is exactly the case when truly dangerous dirt is poorly visible against the background of harmless dirt. Water studies by the Yellow River Conservation Committee in the late 2000s showed that at least a third of the river below the city of Lanzhou is unsuitable for any use, according to UN criteria. The reason for this was the constant extensive emissions from chemical and oil refineries. However, the river continues to serve as the main source of water for the growing cities and agriculture in the lower reaches.
America, Mississippi. One of largest rivers world, whose basin provides fresh water 40% of the US territory. It is also the largest shipping route and a source of energy for numerous hydroelectric power stations. It contains both industrial and agricultural waste. As a result, up to 600 million tons of wastewater are discharged into the Gulf of Mexico annually.
The waters of the Gulf at the mouth of the Mississippi are literally dead, almost no organisms survive there. Numerous treatment plants pass through all these millions of cubic meters of contaminated water, but fail to cope with their main task.
Australia also did not avoid the mistakes of the Old World. The dirtiest river on the continent is located in Tasmania and is named King River. It's essentially an acid river. Its “poisoner” is the largest copper mine, which began work at the end of the 19th century. It took him about a hundred years for the river to break pollution records.
The mine was closed in 1995, a protective dam was even built, but the Tasmanian Environmental Protection Department still talks about one and a half million tons of sulfides, acids and metals per year.
Considered the dirtiest river in Europe Italian river Sarno. It often spills and washes away chemical fertilizers from the fields. There is no optimal solution to the problem.
Dirty rivers of Russia
Let’s move on from global problems of hydroecology to closer, domestic ones.The Volga is a feeding river; historically it has been a source of water, fish, and a living transport system. Naturally, in our time a significant part of industrial cities is concentrated on it. In addition, 65 of the 100 most polluted cities in Russia are located in the Volga basin. It's no surprise that this river is having a hard time.
In recent decades, ecologists have been talking about the critical state of the Volga biosphere: mutations of fish, excessive proliferation of certain types of algae are observed, the chemical composition of water near industrial wastewater does not stand up to criticism. The river's ability to self-purify can no longer ensure the balance of the ecosystem.
Unfortunately, almost any large city has a negative impact on the environment, and nowadays more and more bodies of water fall into the risk zone.
Dirty Moscow River
The largest urban agglomeration in Russia is located on the Moscow River, which cannot but affect the environment. To monitor the situation, environmental organizations constantly take water samples. Roshydromet uses a scale from 3 to 6 degrees to assess pollution. If at the entrance of the river to the city the state of the water is assessed as moderately polluted (grade 3), then at the exit of waste in the river there is already twice as much water as the actual water (grade 5). You can list all the polluting elements directly according to the periodic table, except that the situation with radiation is not so bad so far.Moscow River in spawning ban:(
Grade 5 water is considered unsuitable for drinking, industrial use and even agriculture. And this despite the fact that every year the city government spends several billion rubles on water purification measures.
However, no warnings from environmentalists stop Muscovites: they continue not only to swim calmly, but even in some places outside the city to wash cars in the river, making their modest contribution to the list of heavy metals dissolved in the river...
The dirtiest river in the world
A few decades ago, the Indonesian Citarum River was an ordinary, fairly clean, full of fish, but now it is easier to catch a plastic bottle in it than living creature. Now Chitarum is an example of the dirtiest river, both in terms of water composition and appearance.This is the undoubted leader in the volume of industrial discharges per unit of time, in the amount of garbage in the water and on the banks. How did this happen? It's simple: a man came to the river, and, as always, did not think about the consequences of his activities. The length of Citarum is only 300 kilometers, and more than 500 buildings have been built on it since the early eighties of the last century. industrial enterprises. Almost two pieces per kilometer of river.
The most polluted river in India. River Yamuna. (River Yamuna India)
The industries did not care too much about preserving the river, since it was only about making the process cheaper, and the residents of the growing cities followed them.
Meanwhile, the longest river in the world, the Amazon, is not considered too dirty.
Subscribe to our channel in Yandex.Zen
Water pollution is a decrease in its quality as a result of various physical, chemical or biological substances entering rivers, streams, lakes, seas and oceans. Water pollution has many causes.
Wastewater
Industrial wastewater containing inorganic and organic waste, often descend into rivers and seas. Every year, thousands of chemicals enter water sources, the effect of which on the environment is not known in advance. Hundreds of these substances are new compounds. Although industrial wastewater is in many cases pre-treated, it still contains toxic substances, which are difficult to detect.
Domestic wastewater containing, for example, synthetic detergents eventually ends up in rivers and seas. Fertilizers washed off the soil surface end up in drains leading to lakes and seas. All these reasons lead to severe water pollution, especially in closed lakes, bays and fjords.
Solid waste. If there is a large amount of suspended solids in the water, they make it opaque to sunlight and thereby interfere with the process of photosynthesis in water pools. This in turn causes disturbances in the food chain in such pools. In addition, solid waste causes siltation in rivers and shipping channels, necessitating frequent dredging.
Eutrophication. Industrial and agricultural wastewater that enters water sources contains high levels of nitrates and phosphates. This leads to oversaturation of closed reservoirs with fertilizing substances and causes increased growth of protozoan algae microorganisms in them. Blue-green algae grows especially strongly. But, unfortunately, it is inedible for most fish species. The growth of algae causes more oxygen to be absorbed from the water than can be naturally produced in the water. As a result, the WIC of such water increases. Getting into the water biological waste, such as wood pulp or untreated sewage water, also leads to increased WIC. Other plants and living things cannot survive in such an environment. However, microorganisms that are capable of decomposing dead plant and animal tissues multiply rapidly in it. These microorganisms absorb even more oxygen and form even more nitrates and phosphates. Gradually, the number of plant and animal species in such a reservoir decreases significantly. The most important victims of the ongoing process are fish. Ultimately, the decrease in oxygen concentration due to the growth of algae and microorganisms that decompose dead tissue leads to the aging of lakes and their waterlogging. This process is called eutrophication.
A classic example of eutrophication is Lake Erie in the USA. Over 25 years, the nitrogen content in this lake has increased by 50%, and the phosphorus content by 500%. The cause was mainly the entry into the lake of household wastewater containing synthetic detergents. Synthetic detergents contain a lot of phosphates.
Wastewater treatment is ineffective because it removes only solids and only a small proportion of dissolved nutrients from the water.
Toxicity of inorganic waste. The discharge of industrial wastewater into rivers and seas leads to an increase in the concentration of toxic heavy metal ions, such as cadmium, mercury and lead. A significant part of them is absorbed or adsorbed by certain substances, and this is sometimes called the process of self-purification. However, in closed pools, heavy metals can reach dangerously high levels.
Most famous case this kind occurred in Minamata Bay in Japan. Industrial wastewater containing methyl mercury acetate was discharged into this bay. As a result, mercury began to enter the food chain. It was absorbed by algae, which were eaten by shellfish; Fish ate shellfish, and fish was eaten by the local population. The mercury content in fish turned out to be so high that it led to the appearance of children with congenital deformities and deaths. This disease is called Minamata disease.
Increased nitrate levels observed in drinking water are also of great concern. It has been suggested that high levels of nitrates in water can lead to stomach cancer and cause increased child mortality.
However, the problem of water pollution and its unsanitary condition is not limited to developing countries. A quarter of everything Mediterranean coast considered dangerously contaminated. According to the pollution report Mediterranean Sea, published in 1983 as part of the United Nations Environment Programme, eating shellfish and lobsters caught there is unsafe for health. Typhoid, paratyphoid, dysentery, polio, viral hepatitis and food poisoning, and cholera outbreaks occur periodically. Most of these diseases are caused by the discharge of untreated sewage into the sea. It is estimated that 85% of waste from 120 coastal cities is dumped into the Mediterranean Sea, where holidaymakers and tourists swim and fish. local residents. Between Barcelona and Genoa, every mile of coastline produces approximately 200 tons of waste per year.
Pesticides
The most toxic pesticides are halogenated hydrocarbons, such as DDT and polychlorinated biphenyls. Although DDT has already been banned for use in many countries, it is still used in others, and approximately 25% of the amount used reaches the sea. Unfortunately, these halogenated hydrocarbons are chemically stable and cannot be decomposed by microorganisms. Therefore, they accumulate in the food chain. DDT can destroy all life on the scale of entire river basins; it also prevents birds from breeding.
Oil leak
In the United States alone, approximately 13,000 oil spills occur annually. IN sea water up to 12 million tons of oil fall annually. In the UK, over 1 million tons of used engine oil are poured down the drain every year.
Oil spilled into sea water has many adverse effects on sea life. First of all, birds die - they drown, overheat in the sun or are deprived of food. Oil blinds animals living in the water - seals and seals. It reduces the penetration of light into enclosed bodies of water and can increase water temperature. This is especially destructive for organisms that can exist only in a limited temperature range. Oil contains toxic components, e.g. aromatic hydrocarbons, which have a detrimental effect on some forms of aquatic life even in concentrations as low as a few parts per million.
O.V.Mosin
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 natural level, causing their oppression, degradation and death.
There are several types of water pollution:
Chemical water pollution seems to be the most dangerous at present due to the global scale of this process and the growing number of pollutants, including many xenobiotics, i.e. substances alien to aquatic and near-water 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 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 in the 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 ground waters 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 water that disrupts gas exchange between water and the atmosphere. Phosphates included in surfactants cause eutrophication of water bodies.
The use of mineral and organic fertilizers leads to contamination of soils, surface and ground waters with nitrogen compounds, 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 in warm season in water bodies susceptible 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 the MPC), moderate (3-fold excess of the MPC), high (10-fold excess of the 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 the 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.
Protection of natural resources and quality assurance natural waters- 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.
How humans pollute the hydrosphere, you will learn from this article.
How does a person pollute water?
Hydrosphere- This aquatic environment, which includes underground and surface water. Today, man's activities have led to massive water pollution.
Main types of pollution:
- Pollution from petroleum products and oil. Oil slicks prevent sunlight from reaching the water column and slow down the process of photosynthesis.
- Wastewater pollution due to mineral and organic fertilizer soil and industrial production. Algae in water bodies begin to actively reproduce and lead to waterlogging and death of other ecosystems.
- Pollution with heavy metal ions.
- Acid rain.
- Radioactive contamination.
- Thermal pollution. Emissions from nuclear power plants and thermal power plants contribute to the development of blue-green algae and water blooms.
- Mechanical contamination.
- Biological and bacterial contamination promotes the development of pathogenic organisms and fungi.
How do people pollute the ocean and seas?
Every year more than 10 million tons of oil enter the Ocean. Today, about 20% of its area is covered with an oil film. The problem of pollution from industrial waste and household waste is especially acute. Often, marine inhabitants swallow plastic and bags and die either from suffocation or from the fact that this garbage gets stuck in the body. A serious environmental threat to the world's oceans and seas is the human burial of radioactive waste and the dumping of radioactive liquid waste.
How do people pollute rivers and lakes?
In the process of human industrial activity, large amounts of petroleum products, wastewater, and radioactive liquid substances enter the waters of lakes and rivers. Pesticides are especially dangerous. Once in the water, they instantly dissipate and reach a maximum degree of concentration. Waste from nuclear fuel and weapons-grade plutonium destroys the fauna of these water bodies.
How do people pollute groundwater?
They suffer greatly from oil fields, filtration fields, the mining industry, slag dumps, chemical fertilizer and waste storage facilities, metallurgical plant dumps, and sewers. As a result, groundwater is polluted with phenols, copper, zinc, petroleum products, nickel, mercury, sulfates, and chlorides.
We hope that from this article you learned how people pollute water.