Polluted water. Main sources of water pollution

Decor elements 13.10.2019

Decor elements

Water pollution is a decrease in its quality as a result of getting into rivers, streams, lakes, seas and oceans of various physical, chemical or biological substances. Water pollution has many causes.

Wastewater

Industrial effluents containing inorganic and organic waste are often discharged 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 effluents are pre-treated in many cases, they still contain toxic substances that are difficult to detect.

Domestic wastewater containing e.g. synthetic detergents eventually end 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 pools, lakes and ponds.

solid waste.

If it is in the water a large number of suspended solids, they make it opaque to sunlight and thereby interfere with the process of photosynthesis in water basins. This in turn causes disturbances in the food chain in such pools. In addition, solid waste causes silting up of rivers and shipping channels, resulting in the need for frequent dredging.

Eutrophication.

In industrial and agricultural sewage that enter water sources, the content of nitrates and phosphates is high. This leads to a supersaturation of closed reservoirs with fertilizing substances and causes an increased growth of the simplest algae microorganisms in them. Blue-green algae grows especially strongly. But, unfortunately, it is inedible for most species of fish. Algae growth leads to absorption from the water more oxygen than can naturally form in it. The result is an increase in the BOD of such water. Biological waste entering the water, such as wood pulp or untreated sewage water also leads to an increase in BOD. Other plants and living beings cannot survive in such an environment. However, microorganisms that can decompose dead plant and animal tissues multiply strongly in it. These microorganisms absorb even more oxygen and form even more nitrates and phosphates. Gradually, in such a reservoir, the number of plant and animal species is significantly reduced. The most important victims of the ongoing process are fish. Ultimately, a decrease in oxygen concentration as a result of the growth of algae and microorganisms that decompose dead tissues leads to the aging of lakes and their waterlogging. This process is called eutrophication.

A classic example of eutrophication is Lake Erie in the United States. For 25 years, the nitrogen content in this lake has increased by 50%, and the phosphorus content by 500%. The reason was mainly the ingress of domestic wastewater containing synthetic detergents into the lake. Synthetic detergents contain a lot of phosphates.

Wastewater treatment does not give the desired effect, since it allows you to remove from the water only solids and only a small fraction of the nutrients dissolved in it.

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 enclosed pools, heavy metals can reach dangerously high levels.

The most famous case of this kind occurred in Minamata Bay in Japan. Industrial wastewater containing methylmercury acetate was discharged into this bay. As a result, mercury began to enter the food chain. It was absorbed by algae, which ate shellfish; fish ate shellfish, and fish was eaten by the local population. The mercury content of the fish was found to be so high that it led to birth defects and deaths in children. This disease is called Minamata disease.

Of great concern is also the increase in nitrate levels observed in drinking water. The opinion is expressed that high content nitrates in water can lead to stomach cancer and cause increased infant mortality.

Microbiological contamination of water.

However, the problem of water pollution and its unsanitary condition is not limited to developing countries. A quarter of the entire Mediterranean coast is considered dangerously polluted. According to pollution report mediterranean sea, published in 1983 as part of the Protection Program environment UN, eating shellfish and lobster caught there is unsafe for health. Typhus, paratyphoid, dysentery, poliomyelitis, viral hepatitis and food poisoning, cholera outbreaks occur periodically. Most of these diseases are caused by the discharge of raw sewage into the sea. It is estimated that 85% of waste from 120 coastal cities is dumped into the Mediterranean Sea, where tourists and locals swim and fish. Between Barcelona and Genoa, approximately 200 tons of waste is dumped per mile of coastline per year.

oil leak

In the US alone, there are approximately 13,000 oil spills each year. AT sea water up to 12 million tons of oil enter annually. In the UK, more than 1 million tons of used engine oil is poured into the sewers every year.

Oil spilled into seawater has many adverse effects on marine life. First of all, birds die - drowning, overheating in the sun or deprived of food. Oil blinds animals living in the water - seals, seals. It reduces the penetration of light into closed water bodies and can increase the temperature of the water. This is especially detrimental to organisms that can only exist in a limited temperature range. Oil contains toxic components such as aromatic hydrocarbons, which have a detrimental effect on some forms of aquatic life, even in concentrations such as a few parts per million.

Other forms of water pollution

These include radioactive and thermal pollution. The main source of radioactive pollution of the sea is low-level waste removed from nuclear power plants. One of the most important issues arising from this contamination is that marine organisms such as algae accumulate, or concentrate, radioactive isotopes.

Thermal water pollution is caused by thermal or nuclear power plants. Thermal pollution is introduced into the surrounding water bodies by waste cooling water. As a result, an increase in water temperature in these reservoirs leads to the acceleration of some biochemical processes in them, as well as to a decrease in the oxygen content dissolved in water. This causes rapid and often very significant changes in the biological environment in the vicinity of power plants. There is a violation of the finely balanced cycles of reproduction of various organisms. In conditions of thermal pollution, as a rule, there is a strong growth of algae, but the extinction of other organisms living in the water.

The pollutant poses a danger to living organisms such as plants or animals. Contaminants can be the result of human activity, such as a by-product of industry, or occur naturally, such as radioactive isotopes, fallout, or animal waste.

Because of how broad the concept of pollution is, it can be assumed that polluted waters existed even before the appearance of the negative activities of mankind.

However, the amount of polluted waters is increasing due to rapid population growth, agricultural activities and industrial development.

Main sources of water pollution

A number of human actions lead to water pollution that is harmful to aquatic life, aesthetic beauty, recreation and human health. The main sources of pollution can be grouped into several categories:

land use

Mankind impacts the land to a large extent, including the cultivation of meadows, the construction of buildings, the laying of roads, etc. Land use leads to disruption during precipitation and snowmelt. As water flows over the barren land and forms streams, it takes over everything in its path, including harmful substances. Vegetation is important because it holds back the organic and mineral components of the soil.

Impenetrable surfaces

Most artificial surfaces cannot absorb water like soil and roots. Rooftops, parking lots, and roads allow rain or melted snow to run off high speed and volume, picking up heavy metals, oils, road salt and other contaminants along the way. Otherwise, the pollutants would be absorbed by the soil and vegetation, and would naturally break down. Instead, they concentrate in wastewater and then end up in bodies of water.

Agriculture

General agricultural practices such as soil exposure to fertilizers and pesticides and livestock concentration contribute to water pollution. Water saturated with phosphorus and nitrates leads to algal blooms and other problems, including. Improper management of agricultural land and livestock can also lead to significant soil erosion.

Mining

Mine tailings are piles of discarded stones after the valuable part of the ore has been removed. Tailings can leach to surface and ground water a large number of pollutants. By-products are sometimes stored in artificial reservoirs, and the absence of dams to hold back these reservoirs can lead to an ecological disaster.

Industry

Industrial activity is the main source of water pollution. In the past, liquid waste was dumped directly into rivers or placed in special barrels, which were then buried somewhere. These barrels then began to break down, and harmful substances seep into the soil and then into The groundwater. In addition, accidental spills of pollutants are quite common and result in Negative consequences for human health and

Energy sector

The extraction and transportation of fossil fuels, especially oil, results in spills that can have long-term impacts on water resources. In addition, coal-fired power plants emit large amounts of sulfur dioxide and nitrogen oxides into the atmosphere. When these pollutants dissolve in rainwater and enter waterways, they significantly acidify rivers and lakes. Hydroelectric power generation results in significantly less pollution, but still has some harmful effect to aquatic ecosystems.

home activities

There are many actions we can take every day to prevent water pollution: avoid using pesticides, collect pet waste, dispose of household chemicals and medical preparations, avoid plastic, watch out for oil leaks in the car, clean regularly drain pits and etc.

Trash

A lot of garbage is stored in the environment, and plastic products are not subject to biodegradation, but only break down into harmful microparticles.

Is a substance always a pollutant?

Not always. For example, nuclear power plants use great amount water to cool the reactor using a steam generator. The warm water then flows back into the river from which it is pumped, creating a warm plume that affects aquatic life downstream.

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For a long time, the problem of water pollution was not acute for most countries. The resources available were sufficient to meet the needs local population. With the growth of industry, the increase in the amount of water used by man, the situation has changed dramatically. Now the issues of its purification and preservation of quality are being dealt with at the international level.

Methods for determining the degree of pollution

Water pollution is commonly understood as a change in its chemical or physical composition, biological characteristics. This defines restrictions on further use of the resource. Pollution deserves more attention fresh water because their purity is inextricably linked to the quality of life and human health.

In order to determine the state of water, a number of indicators are measured. Among them:

chromaticity;
degree of turbidity;
smell;
pH level;
content of heavy metals, trace elements and organic matter;
coli titer;
hydrobiological indicators;
the amount of oxygen dissolved in water;
oxidizability;
the presence of pathogenic microflora;
chemical oxygen demand, etc.

In almost all countries, there are supervisory authorities that must determine the quality from the contents at certain intervals, depending on the degree of importance of a pond, lake, river, etc. If deviations are found, the reasons that could provoke water pollution are identified. Then steps are taken to eliminate them.

What causes resource pollution?

There are many reasons that can cause water pollution. It is not always associated with human activity or industrial enterprises. Natural disasters, which occur periodically in different areas, can also disrupt environmental conditions. The most common reasons are considered to be:

Domestic and industrial waste water. If they do not pass the synthetic cleaning system, chemical elements and organic substances, then, getting into water bodies, they are capable of provoking a water-environmental catastrophe.
. This problem is not talked about so often, so as not to provoke social tension. But the exhaust gases that enter the atmosphere after the emissions of road transport, industrial enterprises, along with rains, end up on the ground, polluting the environment.
Solid waste, which can not only change the state of the biological environment in the reservoir, but also the flow itself. Often this leads to flooding of rivers and lakes, obstruction of the flow.
Organic pollution associated with human activities, natural decomposition of dead animals, plants, etc.
Industrial accidents and man-made disasters.
Floods.
Thermal pollution associated with the production of electricity and other energy. In some cases, water is heated up to 7 degrees, which causes the death of microorganisms, plants and fish, which require a different temperature regime.
Avalanches, mudflows, etc.

In some cases, nature itself is able to clean up over time. water resources. But period chemical reactions will be big. Most often, the death of inhabitants of reservoirs and pollution of fresh water cannot be prevented without human intervention.

The process of moving pollutants in water

If we are not talking about solid waste, then in all other cases, pollutants can exist:

in a dissolved state;
in a balanced state.

They may be droplets or small particles. Biocontaminants are observed in the form of live microorganisms or viruses.

If solid particles get into the water, they will not necessarily settle to the bottom. Depending on the current, storm events, they are able to rise to the surface. An additional factor is the composition of the water. In the sea, it is almost impossible for such particles to sink to the bottom. As a result of the current, they easily move over long distances.

Experts draw attention to the fact that due to the change in the direction of the current in coastal zones traditionally the level of pollution is higher.

Regardless of the type of pollutant, it can enter the body of fish that live in a reservoir, or birds that are looking for food in the water. If this does not lead to the direct death of the creature, then it can affect the further food chain. There is a high probability that this is how water pollution poisons people and worsens their health.

The main results of the impact of pollution on the environment

Regardless of whether the pollutant enters the body of a person, fish, animal, a protective reaction is triggered. Some types of toxins can be neutralized by immune cells. In most cases, a living organism needs help in the form of treatment so that the processes do not become serious and do not lead to death.

Scientists determine, depending on the source of pollution and its influence, the following indicators of poisoning:

Genotoxicity. Heavy metals and other trace elements are ways to damage and change the structure of DNA. As a result, serious problems are observed in the development of a living organism, the risk of diseases increases, etc.
Carcinogenicity. The problems of oncology are closely related to what kind of water a person or animals consumes. The danger lies in the fact that a cell, having turned into a cancer cell, is able to quickly regenerate the rest in the body.
neurotoxicity. Many metals, chemicals can affect nervous system. Everyone knows the phenomenon of the release of whales, which is provoked by such pollution. The behavior of sea and river inhabitants becomes inadequate. They are not only able to kill themselves, but also begin to devour those who were previously uninteresting to them. Getting into the human body with water or food from such fish and animals, chemicals can provoke a slowdown in the reaction of the brain, destruction nerve cells etc.
Violation of energy exchange. By acting on mitochondrial cells, pollutants are able to change the processes of energy production. As a result, the body ceases to carry out active actions. Lack of energy can cause death.
reproductive insufficiency. If water pollution causes the death of living organisms not so often, then it can affect the state of health in 100 percent of cases. Scientists are especially concerned that their ability to reproduce a new generation is being lost. Solving this genetic problem is not easy. Requires artificial renewal of the aquatic environment.

How does water control and treatment work?

Realizing that pollution of fresh water endangers human existence, government agencies at the national and international level create requirements for the implementation of enterprises and people's behavior. These frameworks are reflected in the documents regulating the procedures for water control and the operation of purification systems.

There are the following cleaning methods:

Mechanical or primary. Its task is to prevent large objects from entering the reservoirs. To do this, special gratings and filters are installed on the pipes through which the drains go. It is required to clean the pipes in a timely manner, otherwise the blockage can cause an accident.
Specialized. Designed to capture pollutants of a single type. For example, there are traps for fats, oil slicks, flocs, which are deposited with the help of coagulants.
Chemical. It implies that wastewater will be reused in a closed cycle. Therefore, knowing their composition at the outlet, they select chemicals that are able to return water to its original state. Usually this is technical water, not drinking water.
Tertiary cleaning. So that water can be used in everyday life, agriculture, in Food Industry, its quality must be impeccable. To do this, it is treated with special compounds or powders that are capable of delaying heavy metals, harmful microorganisms and other substances.

Everything in life more people tries to install powerful filters that eliminate pollution caused by old communications and pipes.

Diseases that dirty water can provoke

Until it became clear that pathogens and bacteria can enter the body with water, humanity was faced with. After all, epidemics observed periodically in a particular country claimed the lives of hundreds of thousands of people.

The most common diseases that can lead to bad water, relate:

cholera;
enterovirus;
giardiasis;
schistosomiasis;
amoebiasis;
congenital deformities;
mental anomalies;
intestinal disorders;
gastritis;
skin lesions;
mucous burns;
oncological diseases;
decrease in reproductive function;
endocrine disorders.

The purchase of bottled water and the installation of filters is a means of preventing diseases. Some use silver items, which also partially disinfect the water.

Water pollution has the power to change the planet and make the quality of life completely different. That is why the issue of water conservation is constantly raised by environmental organizations and research centers. This allows you to draw the attention of enterprises, the public, government agencies to existing problems and stimulate the start of active actions to prevent a catastrophe.

Water needs. It is clear to everyone how great is the role of water in the life of our planet and especially in the existence of the biosphere. Recall that the tissues of most plant and animal organisms contain from 50 to 90 percent water (with the exception of 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 for only a few days without drinking (and without food, he can live for more than a month). The biological need of man and animals for water per year is 10 times higher than their own weight. Even more impressive are the household, industrial and agricultural needs of man. So, for the production of a ton of soap, 2 tons of water are required, 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, mankind used 3494 cubic kilometers of water for various needs (66 percent in agriculture, 24.6 percent in industry, 5.4 percent for domestic needs, and 4 percent evaporation from the surface of artificial reservoirs). This represents 9-10 percent of the global river flow. During use, 64 percent of the withdrawn water evaporated, and 36 percent were 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 of fresh water for all needs (about 10 percent from underground sources), that is, approximately 1,200 tons per capita. Of the total, 38 percent went to industry, 53 percent to agriculture (including dryland irrigation), and 9 percent to drinking and household needs. In 1988, about 355-360 cubic kilometers were already taken.

Water pollution. The water used by man is eventually returned to the natural environment. But, apart from evaporated water, it is no longer pure water, but domestic, industrial and agricultural wastewater, usually not treated or treated insufficiently. Thus, there is pollution of freshwater reservoirs - rivers, lakes, land and coastal areas of the seas. In our country, out of 150 cubic kilometers of sewage, 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 poisonous 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 waters of the seas are domestic sewage, which contains feces, 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 contamination 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 (so-called lactose-positive, or LPC) in a liter of water. It characterizes the contamination of water 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 LCP per liter. If the water contains from 5,000 to 50,000 LCPs per liter, then the water is considered dirty, and there is a risk of infection when bathing. If a liter of water contains more than 50,000 LCPs, then bathing is unacceptable. It is clear that after disinfection by chlorination or ozonation, drinking water must meet much more stringent standards.

To characterize the contamination with organic substances, another indicator is used - biochemical oxygen demand (BCD). It shows how much oxygen is required by microorganisms to process all decomposable organic matter into inorganic compounds (for, say, five days - then this is BOD 5. According to the BOD 5 standards adopted in our country, 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 VPK. Drinking water must contain more than 4 milligrams of dissolved oxygen per liter.

chemical pollution created by the introduction of various toxic substances into the water. The main sources of chemical pollution are blast furnace and steel production, non-ferrous metallurgy, 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 water surface directly from the air.

In table. Table 3 shows the rates of contamination of surface waters with toxic heavy metals (according to the data of the same authors as the data on air and soil pollution by metals). 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, running a little ahead, ocean waters) among heavy metals, lead holds the palm: its ratio of an artificial source to a natural one exceeds 17. Other heavy metals - copper, zinc, chromium, nickel , cadmium is an artificial source of entry into natural waters also more natural, but not as much as lead. Mercury pollution from the air, forests and fields treated with pesticides, and sometimes as a result of industrial discharges, poses a great danger. The runoff of water from mercury deposits or mines is extremely dangerous, where mercury can turn into soluble compounds. This threat makes reservoir projects on the Altai Katun River extremely dangerous.

In recent years, there has been a significant increase in the flow of surface water land of nitrates due to the irrational use of nitrogen fertilizers, as well as due to increased emissions into the atmosphere from car exhaust. The same applies to phosphates, for which, in addition to fertilizers, the increasing use of various detergents serves as a source. dangerous chemical pollution create hydrocarbons - oil and products of its processing, which enter rivers and lakes both with industrial discharges, especially during the extraction and transportation of oil, and as a result of washing off the soil and falling out of the atmosphere.

Dilution of sewage. To make wastewater more or less usable, it is subjected to multiple dilutions. But it would be more correct to say that at the same time, pure natural waters that could be used for any purpose, including drinking, become less suitable for this, polluted. So, if dilution by a factor of 30 is considered mandatory, then, for example, to dilute 20 cubic kilometers of sewage discharged into the Volga, 600 cubic kilometers of pure water would be needed, which is more than twice the annual flow of this river (250 cubic kilometers). To dilute all the effluents discharged into the rivers in our country, 4,500 cubic kilometers of pure 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 is almost no clean surface water left in our country.

Dilution of wastewater reduces the quality of water in natural reservoirs, but usually does not reach its main goal- prevention of 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, in the process of breathing and feeding, filter a large amount of water (mollusks, sponges, etc.) and, ultimately, both along the food chain and in the process of breathing concentrated in the tissues of fish. As a result, the concentration of poisons in the tissues of fish can become hundreds and even thousands of times greater than in water.

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

The dilution of industrial effluents, and especially solutions of fertilizers and pesticides from agricultural fields, often occurs already in the natural reservoirs themselves. If the reservoir is stagnant or slow-flowing, then the discharge of organic matter and fertilizers into it leads to an overabundance of nutrients - eutrophication and overgrowth of the reservoir. First, in such a reservoir accumulate nutrients and thriving algae, mostly microscopic blue-greens. After their death, the biomass sinks to the bottom, where it is mineralized with the consumption of a large amount of oxygen. Conditions in the deep layer of such a reservoir become unsuitable for the life of fish and other organisms that need oxygen. When all oxygen is exhausted, oxygen-free fermentation begins with the release of methane and hydrogen sulfide. Then there is a poisoning of the entire reservoir and the death of all living organisms (except for some bacteria). Such an unenviable fate threatens not only lakes into which domestic and industrial waste 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 vivid example of this is the current state of the Volga, which is more of a cascade of slow-flowing reservoirs than a river in the original sense of the word. The damage is obvious: it is both an acceleration of pollution and death aquatic organisms in places of water intake, and disruption of habitual migratory movements, and the loss of valuable agricultural land, and much more. And is this damage compensated by the energy produced at hydroelectric power plants? It is necessary to recalculate all the pros and cons, taking into account the modern environmental requirements of the existence of people. And it may turn out to be more expedient to dismantle some dams and liquidate reservoirs than to suffer losses from year to year.

physical pollution water is created by the discharge of heat or radioactive substances into them. 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 produced) is discharged into the same reservoir. Some industries 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 ceased to freeze in winter. On the Moskva River within Moscow, ice floes are now rarely seen in winter, and recently, at the confluence of some rivers (for example, Setun) and discharges of thermal power plants, polynyas were observed with wintering ducks on them. On some rivers of the industrial east of the USA, in the late 60s, the water heated up to 38˚ and even up to 48˚ in summer.

With significant thermal pollution, the fish suffocates and dies, as its oxygen demand increases, and the solubility of oxygen decreases. The amount of oxygen in the water also decreases because thermal pollution leads to the rapid development of unicellular algae: the water “blooms” with subsequent decay of the dying plant mass. In addition, thermal pollution significantly increases the toxicity of many chemical pollutants, in particular heavy metals.

During normal operation nuclear reactors neutrons can get into 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 wastes are weakly active, they can still increase the overall background of radioactivity. During accidents, the waste may be more active. In natural water bodies, radioactive substances undergo physical and chemical transformations - concentration on suspended particles (adsorption, including ion exchange), precipitation, sedimentation, transport by currents, absorption by living organisms, accumulation in their tissues. In living organisms, first of all, radioactive mercury, phosphorus, cadmium accumulate, in the soil - vanadium, cesium, niobium, zinc, sulfur, chromium, iodine remain in the water.

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

With river runoff, 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. Especially goes to the inland and semi-enclosed seas, in which the ratio of the catchment areas and the sea itself is greater than that of the entire World Ocean (for example, in the Black Sea it is 4.4 versus 0.4 in the World Ocean). According to minimal estimates, 367,000 tons of organic matter, 45,000 tons of nitrogen, 20,000 tons of phosphorus, and 13,000 tons of oil products enter the Caspian Sea with the flow of the Volga. There is a high content of organochlorine pesticides in tissues sturgeon fish and sprat - the main objects of fishing. In the Sea of Azov, from 1983 to 1987, the content of pesticides increased by 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, lead - by 9 percent.

Pollution coming with river runoff is unevenly distributed over the ocean. About 80-95 percent of the suspended matter and 20 to 60 percent of the dissolved matter of river runoff is lost in river deltas and estuaries and does not enter the ocean. That part of the pollution that nevertheless breaks through the areas of “avalanche sedimentation” in the mouths of the rivers moves mainly along the coast, remaining within the shelf. Therefore, the role of river runoff in the pollution of the open ocean is not as great as previously thought.

Atmospheric sources of ocean pollution for some types of pollutants are comparable to river runoff. This applies, for example, to lead, the average concentration of which in the waters of the North Atlantic has increased from 0.01 to 0.07 milligrams per liter over forty-five years and decreases with depth, directly indicating an atmospheric source. Mercury from the atmosphere comes almost as much as with river runoff. Half of the pesticides found in ocean water 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 pollution of the ocean by oil and oil products. Natural pollution occurs as a result of oil seepage from oil-bearing layers, mainly on the shelf. For example, in the Santa Barbara Strait off the coast of California (USA), an average of almost 3 thousand tons per year enters this way; this seepage was discovered as early as 1793 by the English navigator George Vancouver. In total, from 0.2 to 2 million tons of oil per year enters the World Ocean from natural sources. If we take the lower estimate, which seems to be 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 activities 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 greatest contribution to the oil pollution of the ocean is made by sea transportation of oil. Of the 3 billion tons of oil currently produced, about 2 billion tons are transported by sea. Even with accident-free transport, oil is lost during its loading and unloading, flushing and ballast waters (which fill tanks after oil is unloaded) into the ocean, as well as during the discharge of so-called bilge waters, which always accumulate on the floor of the engine rooms of any ships. Although international conventions prohibit the discharge of oil-polluted 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, 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 error or equipment failure.

But the greatest damage to the environment and the biosphere is caused by sudden spills of large amounts of oil during tanker accidents, although such spills account for only 5-6 percent of the total oil pollution. The record of these accidents is as long as the history of seaborne oil shipments. The first such accident is believed to have occurred on Friday, December 13, 1907, when the seven-masted sailing schooner Thomas Lawson, carrying 1,200 tons of kerosene, crashed against the rocks off the Isles of Scilly near the southwestern 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 position of the vessel, as a result of which it deviated from the course, and a severe storm that tore the schooner from anchors threw it onto the rocks. As a curiosity, we note that the most popular book of the writer Thomas Lawson, whose name was borne by the lost schooner, 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 the Prince William Strait, ran into an underwater rock and ran aground. More than 40 thousand tons of oil poured out of eight holes in its hull, which in 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 slick, expanding, drifted to the southwest, polluting the adjacent shores. Colossal damage was caused to the flora and fauna of the area, many local species were under the threat 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 it was still very far from the complete restoration of the ecological health of the region. The cause of the accident was the irresponsibility of the captain of the ship, who, being in a state of intoxication, entrusted the management of the tanker to an unauthorized person. The inexperienced third assistant, frightened by the ice floes that appeared near, mistakenly changed course, as a result of which the disaster occurred.

In the interval between these two events, at least a thousand oil tankers perished, and there were many more accidents in which it was possible to save the vessel. 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 very different: these are navigational errors, and bad weather, and technical problems, and the irresponsibility of personnel. The desire to reduce the cost of oil transportation led to the appearance of supertankers with a displacement of more than 200,000 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): "Niseki-maru" ( 372 thousand tons); Globtik Tokyo and Globtik London (478 thousand tons each); “Batillus” (540 thousand tons): “Pierre Guillaume” (550 thousand tons) and others. 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, bypassing 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 appeared: supertankers began to break quite often on very large ocean waves, which can be as long as tankers.

The hull of supertankers may not withstand if its middle part is 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-prollers" in South Africa, where the waves, dispersed by the western winds of the “roaring forties”, go to the opposite current of Cape Agulhas, but also in other areas of the ocean.

Today, the catastrophe of the century remains the accident that occurred with the supertanker Amoco Cadiz, which, near the island of Ouessant (Brittany, France), lost control due to malfunctions in the steering mechanism (and the time it took to bargain with the rescue ship) and sat on the rocks near this island. It happened on March 16, 1978. All 223,000 tons of crude oil poured out of the Amoco Cadiz tanks into the sea. This created a severe environmental disaster in the 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, and the coast of France was polluted for 300 kilometers. Within a few kilometers from the accident site (and it happened 1.5 miles from the coast), all living things died: birds, fish, crustaceans, molluscs, and other organisms. According to scientists, never seen biological damage on such a huge area in any of the previous oil pollution. A month after the spill, 67 thousand tons of oil evaporated, 62 thousand tons reached the shore, 30 thousand tons were distributed in the water column (of which 10 thousand tons decomposed under the influence of microorganisms), 18 thousand tons were absorbed by sediments in shallow water and 46 thousand tons were collected from coast and from the surface of the water mechanically.

The main physicochemical and biological processes by which ocean waters self-purify are dissolution, biodegradation, 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 catastrophe, the content of aromatic hydrocarbons in bottom sediments remained 100-200 times higher than the norm. According to scientists, in order to restore complete ecological balance natural environment many years must pass.

Accidental spills occur during offshore oil production, which currently accounts for about a third of global production. On average, such accidents make a relatively small contribution to the oil pollution of the ocean, but individual accidents are catastrophic. These include, for example, the accident at the Ixstock-1 drilling rig in the Gulf of Mexico in June 1979. The oil gusher, which escaped from control, 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 self-cleaning time and damage to the biosphere during oil spills are closely related to climatic and weather conditions, with the prevailing water circulation. Despite the huge amount of oil spilled during the accident on the Ixstock-1 platform, which stretches in a wide strip for a thousand kilometers from the Mexican coast to Texas (USA), only an insignificant part 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, self-purification of polluted waters during the Ex-son Valdez accident in Prince William Bay (Alaska) will take 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 indented rocky shores of Prince William Bay 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.

Due 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 is found by eye in the form of a thin film (with a minimum thickness of up to 0.15 micrometers) and tar 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 on the ocean-atmosphere interface and in the layers adjacent to it. With an increase in ocean pollution, such an 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 affects 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 moistening of the continents largely depends. The oil film makes it difficult to evaporate moisture, and with a sufficiently large thickness (about 400 micrometers) it can reduce it to almost zero. Smoothing out wind waves and preventing the formation of water splashes, which, evaporating, leave tiny particles of salt in the atmosphere, the oil film changes the salt exchange between the ocean and the atmosphere. It can also affect the amount of atmospheric precipitation over the oceans and continents, since salt particles make up a significant part of the condensation nuclei needed to form rain.

Hazardous waste. According to the International Commission on Environment and Development of the United Nations, 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, and not too distant, when hazardous waste from chemical and other enterprises ended up in ordinary city dumps, dumped into water bodies, buried in the ground without taking any precautions. Soon, however, in one country after another, the sometimes very tragic consequences of the careless handling of hazardous waste began to appear more and more often. The broad environmental movement of the public in industrial developed countries forced the governments of these countries to significantly tighten the legislation on the disposal of hazardous waste.

In recent years, the problem of hazardous waste has become truly global. Hazardous wastes have begun to cross national borders more frequently, sometimes without the knowledge of the government or the public in the recipient country. The underdeveloped countries are particularly affected by 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 a small pore in Koko (Nigeria). The cargo was imported from Italy in five consignments from August 1987 to May 1988 using forged documents. The Nigerian government arrested the perpetrators, as well as the Italian merchant ship Piave, in order to send hazardous waste back to Italy. Nigeria withdrew its ambassador from Italy and threatened to take the case to an international court in The Hague. An inspection of the landfill showed that the metal drums contained volatile solvents and that there was a risk of fire or explosion, emitting extremely toxic fumes. About 4,000 barrels were old, rusty, many bloated from the heat, and three of them were found to be highly radioactive. When loading waste for shipment to Italy on the ship "Karin B", which became infamous, loaders and crew members suffered. Some of them received severe chemical burns, others vomited blood, and one person was partially paralyzed. By mid-August, the landfill was cleared of the foreign “gift”.

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 up and dying. It turned out that the cargo delivered by the Norwegian company is 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 what happened, was arrested. The waste has been removed.

Even a complete list of cases known to date will not be exhaustive, since, of course, not all cases are made public. On March 22, 1989, in Basel (Switzerland), representatives of 105 states signed an agreement on the control of the export of toxic waste, which will enter into force after ratification by at least 20 countries. At the heart of this treaty is an indispensable condition: the government of the host country must give written permission in advance to receive the waste. The treaty thus rules out fraudulent transactions, but legitimizes transactions between governments. The green 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 imprudently took on board dangerous goods. The already mentioned “Karin B” and “Deep Sea Carrier”, which exported dangerous cargo from Nigeria, could not immediately unload, a 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. For more than a year, the dangerous cargo traveled with cyanide, pesticides, dioxin and other poisons before it returned aboard the Syrian vessel Zanoobia to the port of departure of Marina de Carrara (Italy).

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

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

Water is one of the most important natural resources, and it is in our power to prevent its pollution. Small changes in habits, such as using natural cleaning products instead of toxic chemicals at home, growing trees and flowers in the garden, can make a huge difference. For larger-scale changes, try not to hush up the facts of discharges of dirty effluents from enterprises into local water bodies. Any action can lead to a positive result.

Steps

Changing household habits

Use as little as possible chemicals when cleaning the house. This simple step can make a big difference. The use of toxic chemicals like bleach or ammonia is not only bad for the water supply, it's simply not necessary. Natural cleaning products are also effective for household care, but they do not harm the environment and the planet's water resources.

Dispose of waste properly. Never dispose of waste that does not decompose down the drain. When you use toxic substances such as paints or ammonia, take care to dispose of them correctly. If you are unsure how to properly dispose of them, consult a hazardous waste collection point or search the Internet for information. Here is a list of some substances that should never be dumped down the drain:

Paints
Engine oil
Solvents and cleaners
Ammonia
Pool chemicals

Do not flush medicines down the drain. Medicines are made from substances that may be harmful to the environment. If you have expired medicines, take them to a hazardous waste collection point, such as mobile collection points - Ecomobiles. So the medicines will not get into the reservoir, they will not harm people and animals.

Do not flush trash down the drain. Flushing items such as diapers, wet wipes, and plastic tampon applicators down the toilet can create sewage problems. In addition, these items will litter rivers and lakes, and this can kill fish and other river and marine life. Instead of flushing such items down the toilet, respectively, just throw them in the trash.
- You can use cloth diapers, recycled toilet paper, biodegradable tampons to minimize the items that end up in the landfill.
Save as much water as possible. Conserving water is very important to conserve the planet's water resources. Purification of drinking water and water for reference household requires a lot of effort and energy, so save as much water as possible, especially during a drought. Here are some good habits that will help you conserve water:

Try not to use plastic. Since plastic is not biodegradable, it accumulates in rivers, lakes, seas, because it has nowhere else to go. For example, the Great Pacific Garbage Patch, or the Eastern Garbage Continent, or the Pacific "garbage swirl" - garbage accumulated in pacific ocean. Garbage that pollutes rivers, seas and lakes harms marine life and people. Whenever possible, use glass containers or cloth bags instead of plastic.
Collect and compost garden waste. If the waste is stored in any way, they can get into sewers, ditches, drains. Even if your waste does not contain herbicides and pesticides, a large number of branches, leaves, and cut grass can oversaturate the water with nutrients.
- Store the compost in a bin or barrel so that the compost doesn't wash out over the area. In some countries, these boxes are provided free of charge or at a low cost.
- Use a lawn mower with a mulch instead of a lawn mower with a grass bag. A lawnmower with mulching adds a natural layer of compost to your lawn, plus you don't have to deal with the disposal of grass clippings.
- Properly dispose of garden waste and grass clippings. If you don't have compost, find out if there are recycling centers in your area.
Monitor the condition of your car. If gasoline or other liquids leak in the machine, remember that they enter through the soil. Regularly inspect the machine, eliminate all faults in a timely manner.
- In addition to the above, remember to properly dispose of your engine oil instead of just dumping it down the drain.
Sharing your ideas and achievements
1. Be active at school or at work. At school or at work, you can take the same steps as at home. Review the rules of the school or office and determine what areas need to be changed to improve water and environmental health in general. Involve friends, teachers, colleagues in this process, tell them about the possibilities of keeping water clean.
  - For example, you can recommend environmentally friendly cleaning products for your school or office, and tell you which of these products are most effective.
  - You can put up signs to remind people to save water in the kitchen and bathroom.
2. Help clean up trash around waterways. If you live near a local water source, there are many things you can do to protect it from pollution. Find out if subbotniks are organized to clean the areas adjacent to the reservoir, be sure to participate in such cleaning as a volunteer to clean the banks of the river, lake, sea.