Problems of clean water in the world and current problems of hydroecology. The problem of clean water Oil pollution of the oceans

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Problems of clean water in the world and current problems of hydroecology. The problem of clean water Oil pollution of the oceans

Among the chemical compounds that a person encounters in his daily life, water is perhaps the most familiar and at the same time the strangest. Its amazing properties have always attracted the attention of scientists, and in recent years they have also become a reason for various pseudo-scientific speculations. Water is not a passive solvent, as is commonly believed, but an active agent in molecular biology; When it freezes, it expands rather than shrinks in volume like most liquids, reaching its greatest density at 4°C. So far, none of the theorists working on the general theory of liquids has come close to describing its strange properties.

Weak hydrogen bonds deserve special mention, thanks to which water molecules form quite complex structures for a short time. An article by Lars Pettersson and his colleagues from Stockholm University, published in 2004 in the journal Science, caused a lot of noise. In particular, it was stated that each water molecule is connected by hydrogen bonds to exactly two others. Because of this, chains and rings appear, with a length of the order of hundreds of molecules. It is along this path that researchers hope to find a rational explanation for the strangeness of water.

But for the inhabitants of our planet, this is not what is primarily interesting about water: without clean drinking water, they will all simply die out, and its availability becomes more and more problematic over the years. According to the World Health Organization (WHO), currently 1.2 billion people do not have enough water, and millions of people die every year from diseases caused by substances dissolved in water. In January 2008, at the UN World Economic Forum (World Economic Forum Annual Meeting 2008), held in Switzerland, it was stated that by 2025, the population of more than half of the world's countries will lack clean water, and by 2050 - 75%.

The problem of clean water is looming from all sides: for example, scientists suggest that in the next 30 years the melting of glaciers (one of the main reserves of fresh water on Earth) will lead to strong jumps in the level of many large rivers, such as the Brahmaputra, Ganges, Yellow River, which will put one and a half billion people in Southeast Asia at risk of running out of drinking water. At the same time, the flow of water, for example, from the Yellow River is already so great that it periodically does not reach the sea.

Declining freshwater supplies

Only 2% of the hydrosphere is fresh water, but it is constantly renewed. The rate of renewal determines the resources available to humanity. Most of the fresh water (85%) is concentrated in the ice of the polar zones and glaciers. The rate of water exchange here is less than in the ocean and amounts to 8000 years. Surface waters on land renew themselves approximately 500 times faster than in the ocean. River waters are renewed even faster, in about 10-12 days. Fresh waters from rivers are of greatest practical importance to humanity.

Rivers have always been a source of fresh water. But in the modern era, they began to transport waste. Waste in the catchment area flows along river beds into the seas and oceans. Most of the used river water is returned to rivers and reservoirs in the form of wastewater. Until now, the growth of wastewater treatment plants has lagged behind the growth of water consumption. And at first glance, this is the root of evil. In reality, everything is much more serious. Even with the most advanced treatment, including biological treatment, all dissolved inorganic substances and up to 10% of organic pollutants remain in the treated wastewater. Such water can again become suitable for consumption only after repeated dilution with pure natural water. And here the ratio of the absolute amount of wastewater, even purified, and the water flow of rivers is important for people.

The global water balance showed that 2,200 km of water per year is spent on all types of water use. Effluent dilution consumes almost 20% of the world's freshwater resources. Calculations for 2000, assuming that water consumption standards will decrease and treatment will cover all wastewater, showed that 30-35 thousand km 3 of fresh water will still be required annually to dilute wastewater. This means that the world's total river flow resources will be close to exhaustion, and in many areas of the world they are already exhausted. After all, 1 km 3 of purified wastewater “spoils” 10 km 3 of river water, and untreated waste water spoils 3-5 times more. The amount of fresh water does not decrease, but its quality drops sharply and it becomes unsuitable for consumption.

Humanity will have to change its water use strategy. Necessity forces us to isolate the anthropogenic water cycle from the natural one. In practice, this means a transition to a closed water supply, to low-water or low-waste, and then to “dry” or non-waste technology, accompanied by a sharp reduction in the volume of water consumption and treated wastewater.

Fresh water reserves are potentially large. However, in any area of the world they can be depleted due to unsustainable water use or pollution. The number of such places is growing, covering entire geographic areas. Water needs are unmet for 20% of the world's urban and 75% of the rural population. The volume of water consumed depends on the region and standard of living and ranges from 3 to 700 liters per day per person.

Industrial water consumption also depends on the economic development of the area. For example, in Canada, industry consumes 84% of all water intake, and in India - 1%. The most water-intensive industries are steel, chemicals, petrochemicals, pulp and paper and food processing. They consume almost 70% of all water spent in industry. On average, industry uses approximately 20% of all water consumed worldwide. The main consumer of fresh water is agriculture: 70-80% of all fresh water is used for its needs. Irrigated agriculture occupies only 15-17% of agricultural land, but produces half of all production. Almost 70% of the world's cotton crops depend on irrigation.

The total flow of rivers in the CIS (USSR) per year is 4,720 km. But water resources are distributed extremely unevenly. In the most populated regions, where up to 80% of industrial production resides and 90% of land suitable for agriculture is located, the share of water resources is only 20%. Many areas of the country are insufficiently supplied with water. These are the south and southeast of the European part of the CIS, the Caspian lowland, the south of Western Siberia and Kazakhstan, and some other regions of Central Asia, the south of Transbaikalia, and Central Yakutia. The northern regions of the CIS, the Baltic states, and the mountainous regions of the Caucasus, Central Asia, Sayan Mountains and the Far East are most supplied with water.

River flows vary depending on climate fluctuations. Human intervention in natural processes has already affected river flow. In agriculture, most of the water is not returned to rivers, but is spent on evaporation and the formation of plant mass, since during photosynthesis, hydrogen from water molecules is converted into organic compounds. To regulate river flow, which is not uniform throughout the year, 1,500 reservoirs were built (they regulate up to 9% of the total flow). Human economic activity has so far had almost no impact on the flow of rivers in the Far East, Siberia and the North of the European part of the country. However, in the most populated areas it decreased by 8%, and in rivers such as Terek, Don, Dniester and Ural by 11-20%. Water flow in the Volga, Syr Darya and Amu Darya has noticeably decreased. As a result, the water inflow to the Sea of Azov decreased by 23%, and to the Aral Sea by 33%. The level of the Aral Sea dropped by 12.5 m.

Limited and even scarce freshwater supplies in many countries are being significantly reduced due to pollution. Typically, pollutants are divided into several classes depending on their nature, chemical structure and origin.

Water pollution from domestic, agricultural and industrial wastewater.

Pathogenic microorganisms and viruses are found in poorly treated or untreated sewage from residential areas and livestock farms. When pathogenic microbes and viruses get into drinking water, they cause various epidemics, such as outbreaks of salmonelliosis, gastroenteritis, hepatitis, etc. In developed countries, the spread of epidemics through public water supplies is rare. Food products, such as vegetables grown in fields that are fertilized with sludge from household wastewater treatment (from German: Schlamme - literally mud), can be contaminated. Aquatic invertebrates, such as oysters or other shellfish, from contaminated water bodies were often the cause of outbreaks of typhoid fever.

Nutrients, mainly nitrogen and phosphorus compounds, enter water bodies with domestic and agricultural wastewater. An increase in the content of nitrites and nitrates in surface and groundwater leads to contamination of drinking water and the development of certain diseases, and the growth of these substances in water bodies causes their increased eutrophication (an increase in the reserves of nutrients and organic substances, due to which plankton and algae rapidly develop, absorbing all the oxygen is in the water).

Inorganic and organic substances also include heavy metal compounds, petroleum products, pesticides (pesticides), synthetic detergents (detergents), and phenols. They enter water bodies with industrial waste, domestic and agricultural wastewater. Many of them either do not decompose at all in the aquatic environment, or decompose very slowly and are capable of accumulating in food chains.

An increase in bottom sediments is one of the hydrological consequences of urbanization. Their number in rivers and reservoirs is constantly increasing due to soil erosion as a result of improper farming, deforestation, and regulation of river flow. This phenomenon leads to a disruption of the ecological balance in aquatic systems and has a detrimental effect on bottom organisms.

Thermal water pollution

Just a few decades ago, polluted waters were like islands in a relatively clean natural environment. Now the picture has changed, continuous areas of contaminated areas have formed.

Oil pollution of the world's oceans

The world's rivers annually carry more than 1.8 million tons of petroleum products into sea and ocean waters.

At sea, oil pollution takes various forms. It can cover the surface of the water in a thin film, and during spills the thickness of the oil coating can initially be several centimeters. Over time, an emulsion of oil in water or water in oil is formed. Later, lumps of the heavy fraction of oil, oil aggregates, appear that can float on the surface of the sea for a long time. Various small animals are attached to the floating lumps of fuel oil, which fish and baleen whales readily feed on. Together with them they swallow oil. Some fish die from this, others are completely saturated with oil and become unfit for consumption due to the unpleasant smell and taste.

All components of oil are toxic to marine organisms. Oil affects the community structure of marine animals. Oil pollution changes the ratio of species and reduces their diversity. Thus, microorganisms that feed on petroleum hydrocarbons develop abundantly, and the biomass of these microorganisms is toxic to many marine inhabitants. It has been proven that long-term chronic exposure to even small concentrations of oil is very dangerous. At the same time, the primary biological productivity of the sea is gradually falling. Oil has another unpleasant side effect. Its hydrocarbons are capable of dissolving a number of other pollutants, such as pesticides and heavy metals, which, together with oil, are concentrated in the surface layer and further poison it. The aromatic fraction of oil contains substances of a mutagenic and carcinogenic nature, for example benzopyrene. There is now extensive evidence of the mutagenic effects of a polluted marine environment. Benzopyrene actively circulates through marine food chains and ends up in human food.

The largest quantities of oil are concentrated in a thin near-surface layer of sea water, which plays a particularly important role for various aspects of ocean life. Many organisms are concentrated in it; this layer plays the role of a “kindergarten” for many populations. Surface oil films disrupt gas exchange between the atmosphere and the ocean. The processes of dissolution and release of oxygen, carbon dioxide, heat exchange undergo changes, and the reflectivity (albedo) of sea water changes.

Birds suffer the most from oil, especially when coastal waters are polluted. Oil sticks the feathers together, it loses its heat-insulating properties, and, in addition, a bird stained with oil cannot swim. Birds freeze and drown. Even cleaning feathers with solvents cannot save all victims. The rest of the sea's inhabitants suffer less. Numerous studies have shown that oil that gets into the sea does not create any permanent or long-term danger to organisms living in water and does not accumulate in them, so its entry into humans through the food chain is excluded.

According to the latest data, significant harm to flora and fauna can only be caused in isolated cases. For example, petroleum products made from it - gasoline, diesel fuel, and so on - are much more dangerous than crude oil. High concentrations of oil in the littoral zone (tidal zone), especially on the sandy shore, are dangerous; in these cases, the concentration of oil remains high for a long time, and it causes a lot of harm. But fortunately such cases are rare.

Usually, during tanker accidents, oil quickly spreads through the water, becomes diluted, and its decomposition begins. It has been shown that oil hydrocarbons can pass through their digestive tract and even through tissues without harm to marine organisms: such experiments were carried out with crabs, bivalves, and various types of small fish, and no harmful effects were found for experimental animals.

Other water pollution

Along with river runoff, heavy metals also enter the ocean, many of which have toxic properties. The total river flow is 46 thousand km of water per year. Together with it, up to 2 million tons of lead, up to 20 thousand tons of cadmium and up to 10 thousand tons of mercury enter the World Ocean. Coastal waters and inland seas have the highest levels of pollution. The atmosphere also plays a significant role in the pollution of the World Ocean. For example, up to 30% of all mercury and 50% of lead entering the ocean each year is transported through the atmosphere. Due to its toxic effects in the marine environment, mercury is particularly dangerous. Microbiological processes convert toxic inorganic mercury into much more toxic organic forms of mercury. Methylated mercury compounds accumulated due to bioaccumulation in fish or shellfish pose a direct threat to human life and health. Let us recall, for example, the notorious “minamato” disease, which received its name from the Gulf of Japan, where mercury poisoning of local residents manifested itself so dramatically. It claimed many lives and undermined the health of many people who ate seafood from this bay, at the bottom of which a lot of mercury accumulated from the waste of a nearby plant.

Mercury, cadmium, lead, copper, zinc, chromium, arsenic and other heavy metals not only accumulate in marine organisms, thereby poisoning marine food, but also have a detrimental effect on sea inhabitants. The accumulation coefficients of toxic metals, i.e. their concentration per unit weight in marine organisms relative to seawater, vary widely - from hundreds to hundreds of thousands, depending on the nature of the metals and the types of organisms. These coefficients show how harmful substances accumulate in fish, shellfish, crustaceans, planktonic and other organisms. The scale of pollution of sea and ocean products is so great that many countries have established sanitary standards for the content of certain harmful substances in them. It is interesting to note that with mercury concentrations in water only 10 times higher than natural levels, oyster contamination already exceeds the limits set in some countries. This shows how close the limit of sea pollution is that cannot be crossed without harmful consequences for human life and health.

There is still a lot of water on the planet, but the share suitable for drinking is rapidly declining.

OnVThe collapse in Darfur province in southern Sudan in 2005 caused severe shortages of drinking water.water. And this is withVThis is not surprising: although there is plenty of water, it is not suitable for drinking. Photo: WHO

USA, Cherokee CountyVabout the drought of 2007. Photo (Creative Commons license): Mark N aka mjn9

In order to avoid a water crisis, new technologies are being developed for water purification and disinfection, desalination, as well as methods for its reuse. However, in addition to scientific research, effective methods for organizing control over the water resources of countries are needed: unfortunately, in most countries, several organizations are involved in the use and planning of water resources (for example, in the USA, more than twenty different federal agencies are involved in this). This topic became the main topic for the March 19 issue of this year of the scientific journal Nature. In particular, Mark Shannon and his colleagues from the University of Illinois at Urbana-Champaign (USA) reviewed new scientific developments and next-generation systems in the following areas: water disinfection and pathogen removal without the use of excessive amounts of chemical reagents and the formation of toxic by-products products; detection and removal of low concentration pollutants; reuse of water, as well as desalination of sea and inland water. Importantly, these technologies must be relatively inexpensive and suitable for use in developing countries.

Subtle infection

New effective disinfection methods must consist of several barriers: removal using physicochemical reactions (for example, coagulation, sedimentation or membrane filtration) and neutralization using ultraviolet light and chemical reagents. Relatively recently, visible spectrum light has again begun to be used for photochemical neutralization of pathogens, and in some cases, combining UV with chlorine or ozone is effective. True, this approach sometimes causes the appearance of harmful by-products: for example, the carcinogen bromate may appear from the action of ozone in water containing bromide ions.

INIndia, where the need for disinfectionwaterfelt up toVVery sharply, Javel water is used for these purposes. Photo: WHO

In developing countries, technology is used to disinfect water in polyethylene terephthalate (PET) bottles using firstly sunlight and secondly sodium hypochloride (this method is used mainly in rural areas). Thanks to chlorine, it was possible to reduce the incidence of gastrointestinal diseases, but in areas where the water contains ammonia and organic nitrogen, the method does not work: chlorine forms compounds with these substances and becomes inactive.

It is expected that in the future, disinfection methods will include the action of ultraviolet radiation and nanostructures. Ultraviolet radiation is effective in combating bacteria living in water and protozoan cysts, but has no effect on viruses. However, ultraviolet light can activate photocatalytic compounds, such as titanium (TiO2), which in turn can kill viruses. In addition, new compounds, such as TiO2 with nitrogen (TiON) or with nitrogen and some metals (palladium), can be activated by radiation in the visible part of the spectrum, which requires less energy than irradiation with ultraviolet light, or even just sunlight. True, such disinfection installations have extremely low productivity.

Another important task in water purification is the removal of harmful substances from it. There are a huge number of toxic substances and compounds (such as arsenic, heavy metals, halogenated aromatic compounds, nitrosamines, nitrates, phosphates and many others). The list of substances suspected of being harmful to health is constantly growing, and many of them are toxic even in minute quantities. Detecting these substances in water and then removing them in the presence of other, non-toxic impurities, the content of which can be an order of magnitude higher, is difficult and expensive. And among other things, this search for one toxin may interfere with the discovery of another, more dangerous one. Pollutant monitoring techniques inevitably involve the use of sophisticated laboratory equipment and skilled personnel, so it is important to find inexpensive and relatively simple means of identifying contaminants wherever possible.

A kind of “specialization” is also important here: for example, arsenic trioxide (As-III) is 50 times more toxic than pentoxide (As-V), and therefore it is necessary to measure their content both together and separately for subsequent neutralization or removal. Existing measurement methods either have a low accuracy limit or require qualified specialists.

Scientists believe that a promising direction in the development of methods for detecting harmful substances is the method of molecular recognition motif, based on the use of sensor reagents (like litmus paper familiar from school), together with micro/nanofluidic manipulation and telemetry. Similar biosensor methods can be applied to pathogenic microorganisms living in water. However, in this case, it is necessary to monitor the presence of anions in the water: their presence can neutralize methods that are quite effective under other conditions. Thus, when treating water with ozone, bacteria die, but if there are Br- ions in the water, oxidation to BrO3- occurs, that is, one type of pollution changes to another.
Reverse osmosis system used in the USA: the water pressure on the side of the synthetic membrane where the pollutants are located exceeds the pressure of clean water on the opposite side. In accordance with the laws of hydrostatics, water seeps through the membrane, purifying itself onto the road. Photo (Creative Commons license): Fred aka fhemerick

In general, there are two ways to combat harmful substances - influencing the micropollutant using chemical or biochemical reagents until it turns into a non-hazardous form, or removing it from the water. This issue is resolved depending on the location. Thus, Sono filtration technology is used in wells in Bangladesh, and reverse osmosis is used in factories in the USA to solve the same problem - removing arsenic from water.

Reverse osmosis system appliedVUSA: pressurewateron the side of the synthetic membrane where the pollutants are located,Vpressure goes downclean waterwith protiVthe opposite side. In accordance with the laws of hydrostatics, water seeps through the membrane, purifying itself onto the road. Photo (Creative Commons license): Fred aka fhemerick

Currently, they are trying to convert organic harmful substances in water through reactions into harmless nitrogen, carbon dioxide and water. Serious anionic contaminants such as nitrates and perchlorates are removed using ion exchange resins and reverse osmosis, and toxic brines are disposed of in storage. In the future, bimetallic catalysts may be used to mineralize these brines, as well as active nanocatalysts in membranes to transform anions.

By V tor use water

Nowadays, environmentalists are passionately dreaming of reusing industrial and municipal wastewater, previously treated to drinking water quality. But in this case, you have to deal with a huge number of all kinds of pollutants and pathogens, as well as organic substances that must be removed or transformed into harmless compounds. Consequently, all operations become more expensive and more complicated.

Municipal wastewater is typically treated in treatment plants, where microbes are suspended to remove organic matter and food residues, and then in settling tanks, where solids and liquids are separated. Water after such purification can be discharged into surface water bodies, and can also be used for limited irrigation and for some factory needs. Currently, one of the actively implemented technologies is membrane bioreactors. This technology combines the use of biomass suspended in water (as in conventional wastewater treatment plants) and aqueous micro- and ultra-thin membranes instead of settling tanks. Water from MBR can be freely used for irrigation and industrial needs.

MBRs can also be of great benefit in developing countries with poor sanitation, especially in fast-growing megacities: they can directly treat wastewater, separating useful substances from it, clean water, nitrogen and phosphorus. MBRs are also used as water pre-treatment for reverse osmosis; if you then treat it with UV (or photocatalytic substances that react to visible light), then it will be suitable for drinking. In the future, it is possible that "water reuse" systems will consist of only two stages: an MBR with a nanofiltration membrane (eliminating the need for a reverse osmosis step) and a photocatalytic reactor, which will serve as a barrier to pathogens and destroy low molecular weight organic pollutants. True, one of the serious obstacles is the rapid clogging of the membrane, and the success of the development of this direction of water purification largely depends on new modifications and properties of membranes.

Environmental laws also pose a significant barrier: in many countries, the reuse of water for municipal purposes is strictly prohibited. However, due to the lack of water resources, this is also changing: for example, in the United States, water reuse is increasing by 15% annually.

Without salt

Increasing fresh water supplies by desalinating the waters of seas, oceans and saline inland waters is a very tempting goal, because these reserves make up 97.5% of all water on Earth. Desalination technologies have come a long way, especially over the past decade, but they still require a lot of energy and capital investment, which has held back their expansion. Most likely, the share of large water desalination plants using the traditional (thermal) method will decrease: they consume too much energy and suffer greatly from corrosion. It is assumed that the future lies in small desalination systems designed for one or several families (this applies mainly to developing countries).

Desalination station. Such structures are not yet commonVyou'll find them quite expensive. But there is no doubt: over time there will be more and more of them. Photo (Creative Commons license): Tom Arthur

Modern desalination technologies use reverse osmosis membrane separation and temperature distillation. Limiting factors for the development of desalination are, as already mentioned, high energy consumption and operating costs, rapid fouling of plant membranes, as well as the problem of brine disposal and the presence of residual low molecular weight pollutants in water, such as boron.

The prospects for research in this direction are determined primarily by a reduction in specific energy costs, and here some progress is evident: if in the 1980s they averaged 10 kWh/m3, now they have decreased to 4 kWh/m3. But there are other important advances: the creation of new materials for membranes (for example, from carbon nanotubes), as well as the creation of new purification biotechnologies.

We can only hope that in the coming years science and technology will really make a big step forward - after all, even while remaining almost invisible to many, the specter of a water crisis has long been wandering not only across Europe, but throughout the world.

MINISTRY OF EDUCATION AND SCIENCE OF RUSSIA
Federal budgetary state educational institution
higher professional education
"Volgograd State Social and Pedagogical University"

Faculty of Economics and Management
Department of Economics and Management

Essay
on the subject “Fundamentals of Ecological Culture”
on the topic “The problem of clean water”

Performed:
1st year student
Group: EU-EB-11
Sokolnikova E.A.
Checked:
Ass. Elantseva A.A.

Volgograd 2013

Introduction………………………………………………………………………..3

1. The essence of the problem of clean water…………………………………………………….4

1.1 Reduction of fresh water reserves…………………………………………..…5

1.2 Water pollution from domestic, agricultural and industrial wastewater…………………………………………………………………………………………7

1.3 Thermal water pollution…………………………………………………………...…..8

1.4 Oil pollution of the World Ocean…………………………………..….8

1.5 Other water pollution…………………………………..….….10

2. Possible solutions……………………………………………..….… ..11

2.1 Water purification……………………………………………………………… 11

2.2 Reuse of water………………………………………….….…14

2.3 Desalination of salt water…………………………………………………………..….…..15

Conclusion……………………………………………………… ……………...….….16

List of references……………………………………………………….….…. 17

Introduction

One could perhaps say that

The purpose of a person is as if

Is to

Destroy your family

Having previously made a globe

Unsuitable for habitation.

J.-B. Lamarck

Once upon a time, people were content with the water they found in rivers, lakes, streams and wells. But with the development of industry and population growth, there is a need to manage water supplies much more carefully to avoid harm to human health and damage to the environment.
A previously inexhaustible resource - fresh, clean water - is becoming exhaustible. Today, water suitable for drinking, industrial production and irrigation is in short supply in many areas of the world. Already, 20 thousand people die annually due to dioxin pollution of water bodies in Russia.
The topic I have chosen is more relevant today than ever, because if not us, then our children will definitely feel the full impact of anthropogenic environmental pollution. However, if you recognize the problem in time and follow the ways to solve it, then an environmental disaster can be avoided.
The purpose of this work is to get acquainted with the problem of clean water as a global environmental problem. In all this, significant attention will be paid to the causes, environmental consequences and possible ways to solve this problem.

1. The essence of the clean water problem

1.1 Declining freshwater supplies

Fresh water resources exist thanks to the eternal water cycle. As a result of evaporation, a gigantic volume of water is formed, reaching 525 thousand km3 per year. 86% of this amount comes from the salty waters of the World Ocean and inland seas - the Caspian, Aral, etc.; the rest evaporates on land, half due to transpiration of moisture by plants. Every year, a layer of water approximately 1250 mm thick evaporates. Some of it falls again with precipitation into the ocean, and some is carried by winds to land and here feeds rivers and lakes, glaciers and groundwater. A natural distiller is powered by the energy of the Sun and takes approximately 20% of this energy.
Only 2% of the hydrosphere is fresh water, but it is constantly renewed. The rate of renewal determines the resources available to humanity. Most of the fresh water (85%) is concentrated in the ice of the polar zones and glaciers. The rate of water exchange here is less than in the ocean and amounts to 8000 years. Surface waters on land renew themselves approximately 500 times faster than in the ocean. River waters are renewed even faster, in about 10-12 days. Fresh waters from rivers are of greatest practical importance to humanity.
Rivers have always been a source of fresh water. But in the modern era, they began to transport waste. Waste in the catchment area flows along river beds into the seas and oceans. Most of the used river water is returned to rivers and reservoirs in the form of wastewater. Until now, the growth of wastewater treatment plants has lagged behind the growth of water consumption. And at first glance, this is the root of evil. In reality, everything is much more serious. Even with the most advanced treatment, including biological treatment, all dissolved inorganic substances and up to 10% of organic pollutants remain in the treated wastewater. Such water can again become suitable for consumption only after repeated dilution with pure natural water. And here the ratio of the absolute amount of wastewater, even purified, and the water flow of rivers is important for people.
The global water balance showed that 2,200 km of water per year is spent on all types of water use. Effluent dilution consumes almost 20% of the world's freshwater resources. Calculations for 2000, assuming that water consumption standards will decrease and treatment will cover all wastewater, showed that 30-35 thousand km3 of fresh water will still be required annually to dilute wastewater. This means that the world's total river flow resources will be close to exhaustion, and in many areas of the world they are already exhausted. After all, 1 km3 of treated wastewater “spoils” 10 km3 of river water, and untreated waste water spoils 3-5 times more. The amount of fresh water does not decrease, but its quality drops sharply and it becomes unsuitable for consumption.
Humanity will have to change its water use strategy. Necessity forces us to isolate the anthropogenic water cycle from the natural one. In practice, this means a transition to a closed water supply, to low-water or low-waste, and then to “dry” or non-waste technology, accompanied by a sharp reduction in the volume of water consumption and treated wastewater.
Fresh water reserves are potentially large. However, in any area of the world they can be depleted due to unsustainable water use or pollution. The number of such places is growing, covering entire geographic areas. Water needs are unmet for 20% of the world's urban and 75% of the rural population. The volume of water consumed depends on the region and standard of living and ranges from 3 to 700 liters per day per person.
Industrial water consumption also depends on the economic development of the area. For example, in Canada, industry consumes 84% of all water withdrawals, and in India - 1%. The most water-intensive industries are steel, chemicals, petrochemicals, pulp and paper and food processing. They consume almost 70% of all water spent in industry. On average, industry uses approximately 20% of all water consumed worldwide. The main consumer of fresh water is agriculture: 70-80% of all fresh water is used for its needs. Irrigated agriculture occupies only 15-17% of agricultural land, but produces half of all production. Almost 70% of the world's cotton crops depend on irrigation.
The total flow of rivers in the CIS (USSR) per year is 4,720 km. But water resources are distributed extremely unevenly. In the most populated regions, where up to 80% of industrial production resides and 90% of land suitable for agriculture is located, the share of water resources is only 20%. Many areas of the country are insufficiently supplied with water. These are the south and southeast of the European part of the CIS, the Caspian lowland, the south of Western Siberia and Kazakhstan, and some other regions of Central Asia, the south of Transbaikalia, and Central Yakutia. The northern regions of the CIS, the Baltic states, and the mountainous regions of the Caucasus, Central Asia, Sayan Mountains and the Far East are most supplied with water.
River flows vary depending on climate fluctuations. Human intervention in natural processes has already affected river flow. In agriculture, most of the water is not returned to rivers, but is spent on evaporation and the formation of plant mass, since during photosynthesis, hydrogen from water molecules is converted into organic compounds. To regulate river flow, which is not uniform throughout the year, 1,500 reservoirs were built (they regulate up to 9% of the total flow). Human economic activity has so far had almost no impact on the flow of rivers in the Far East, Siberia and the North of the European part of the country. However, in the most populated areas it decreased by 8%, and in rivers such as Terek, Don, Dniester and Ural by 11-20%. Water flow in the Volga, Syr Darya and Amu Darya has noticeably decreased. As a result, the water inflow to the Sea of Azov decreased by 23%, and to the Aral Sea by 33%. The level of the Aral Sea dropped by 12.5 m.
Limited and even scarce freshwater supplies in many countries are being significantly reduced due to pollution. Typically, pollutants are divided into several classes depending on their nature, chemical structure and origin.

1.2 Water pollution from domestic, agricultural and industrial wastewater

Organic materials come from domestic, agricultural or industrial wastewater. Their decomposition occurs under the influence of microorganisms and is accompanied by the consumption of oxygen dissolved in water. If there is enough oxygen in the water and the amount of waste is small, then aerobic bacteria quickly transform them into relatively harmless residues. Otherwise, the activity of aerobic bacteria is suppressed, the oxygen content drops sharply, and decay processes develop. When the oxygen content in water is below 5 mg per liter, and in spawning areas - below 7 mg, many fish species die.
Pathogenic microorganisms and viruses are found in poorly treated or untreated sewage from residential areas and livestock farms. When pathogenic microbes and viruses get into drinking water, they cause various epidemics, such as outbreaks of salmonelliosis, gastroenteritis, hepatitis, etc. In developed countries today, the spread of epidemics through public water supplies rarely occurs. Food products, such as vegetables grown in fields that are fertilized with sludge from domestic wastewater treatment (from German Schlamme - literally mud), can be contaminated. Aquatic invertebrates, such as oysters or other shellfish, from contaminated water bodies were often the cause of outbreaks of typhoid fever.
Nutrients, mainly nitrogen and phosphorus compounds, enter water bodies with domestic and agricultural wastewater. An increase in the content of nitrites and nitrates in surface and groundwater leads to contamination of drinking water and the development of certain diseases, and the growth of these substances in water bodies causes their increased eutrophication (an increase in the reserves of nutrients and organic substances, due to which plankton and algae rapidly develop, absorbing all the oxygen is in the water).
Inorganic and organic substances also include heavy metal compounds, petroleum products, pesticides (pesticides), synthetic detergents (detergents), and phenols. They enter water bodies with industrial waste, domestic and agricultural wastewater. Many of them either do not decompose at all in the aquatic environment, or decompose very slowly and are capable of accumulating in food chains.
An increase in bottom sediments is one of the hydrological consequences of urbanization. Their number in rivers and reservoirs is constantly increasing due to soil erosion as a result of improper farming, deforestation, and regulation of river flow. This phenomenon leads to a disruption of the ecological balance in aquatic systems and has a detrimental effect on bottom organisms.

1.3 Thermal water pollution

The source of thermal pollution is heated waste water from thermal power plants and industry. An increase in the temperature of natural waters changes the natural conditions for aquatic organisms, reduces the amount of dissolved oxygen, and changes the metabolic rate. Many inhabitants of rivers, lakes or reservoirs die, the development of others is suppressed.
Just a few decades ago, polluted waters were like islands in a relatively clean natural environment. Now the picture has changed, continuous areas of contaminated areas have formed.

1.4 Oil pollution of the oceans

Oil pollution of the World Ocean is undoubtedly the most widespread phenomenon. From 2 to 4% of the water surface of the Pacific and Atlantic oceans is constantly covered with an oil film. Up to 6 million tons of petroleum hydrocarbons enter sea waters annually. Almost half of this amount is associated with transportation and offshore development. Continental oil pollution enters the ocean through river runoff.
The world's rivers annually carry more than 1.8 million tons of petroleum products into sea and ocean waters.
At sea, oil pollution takes various forms. It can cover the surface of the water in a thin film, and during spills the thickness of the oil coating can initially be several centimeters. Over time, an emulsion of oil in water or water in oil is formed. Later, lumps of the heavy fraction of oil, oil aggregates, appear that can float on the surface of the sea for a long time. Various small animals are attached to the floating lumps of fuel oil, which fish and baleen whales readily feed on. Together with them they swallow oil. Some fish die from this, others are completely saturated with oil and become unsuitable for consumption due to the unpleasant smell and taste.
All components of oil are toxic to marine organisms. Oil affects the community structure of marine animals. Oil pollution changes the ratio of species and reduces their diversity. Thus, microorganisms that feed on petroleum hydrocarbons develop abundantly, and the biomass of these microorganisms is toxic to many marine inhabitants. It has been proven that long-term chronic exposure to even small concentrations of oil is very dangerous. At the same time, the primary biological productivity of the sea is gradually falling. Oil has another unpleasant side effect. Its hydrocarbons are capable of dissolving a number of other pollutants, such as pesticides and heavy metals, which, together with oil, are concentrated in the surface layer and further poison it. The aromatic fraction of oil contains substances of a mutagenic and carcinogenic nature, for example benzopyrene. There is now extensive evidence of the mutagenic effects of a polluted marine environment. Benzpyrene actively circulates through marine food chains and ends up in human food.
The largest quantities of oil are concentrated in a thin near-surface layer of sea water, which plays a particularly important role for various aspects of ocean life. Many organisms are concentrated in it; this layer plays the role of a “kindergarten” for many populations. Surface oil films disrupt gas exchange between the atmosphere and the ocean. The processes of dissolution and release of oxygen, carbon dioxide, heat exchange undergo changes, and the reflectivity (albedo) of sea water changes.
Birds suffer the most from oil, especially when coastal waters are polluted. Oil sticks the feathers together, it loses its heat-insulating properties, and, in addition, a bird stained with oil cannot swim. Birds freeze and drown. Even cleaning feathers with solvents cannot save all victims. The rest of the sea's inhabitants suffer less. Numerous studies have shown that oil that gets into the sea does not create any permanent or long-term danger to organisms living in water and does not accumulate in them, so its entry into humans through the food chain is excluded.
According to the latest data, significant harm to flora and fauna can only be caused in isolated cases. For example, petroleum products made from it - gasoline, diesel fuel, and so on - are much more dangerous than crude oil. High concentrations of oil in the littoral zone (tidal zone), especially on the sandy shore, are dangerous; in these cases, the concentration of oil remains high for a long time, and it causes a lot of harm. But fortunately such cases are rare.
Usually, during tanker accidents, oil quickly spreads through the water, becomes diluted, and its decomposition begins. It has been shown that oil hydrocarbons can pass through their digestive tract and even through tissues without harm to marine organisms: such experiments were carried out with crabs, bivalves, and various types of small fish, and no harmful effects were found for experimental animals.

1.5 Other water pollution

Chlorinated hydrocarbons, widely used as means of controlling agricultural and forestry pests and carriers of infectious diseases, have been entering the World Ocean along with river runoff and through the atmosphere for many decades. DDT and its derivatives, polychlorinated biphenyls and other persistent compounds of this class are now found throughout the world's oceans, including the Arctic and Antarctic. They are easily soluble in fats and therefore accumulate in the organs of fish, mammals, and seabirds. Being xenobiotics, i.e. substances of completely artificial origin, they do not have their “consumers” among microorganisms and therefore almost do not decompose under natural conditions, but only accumulate in the World Ocean. At the same time, they are acutely toxic, affect the hematopoietic system, suppress enzymatic activity, and greatly affect heredity.
Along with river runoff, heavy metals also enter the ocean, many of which have toxic properties. The total river flow is 46 thousand km of water per year. Together with it, up to 2 million tons of lead, up to 20 thousand tons of cadmium and up to 10 thousand tons of mercury enter the World Ocean. Coastal waters and inland seas have the highest levels of pollution. The atmosphere also plays a significant role in the pollution of the World Ocean. For example, up to 30% of all mercury and 50% of lead entering the ocean each year is transported through the atmosphere. Due to its toxic effects in the marine environment, mercury is particularly dangerous. Microbiological processes convert toxic inorganic mercury into much more toxic organic forms of mercury. Methylated mercury compounds accumulated due to bioaccumulation in fish or shellfish pose a direct threat to human life and health. Let us recall, for example, the notorious “minamato” disease, which received its name from the Gulf of Japan, where mercury poisoning of local residents manifested itself so dramatically. It claimed many lives and undermined the health of many people who ate seafood from this bay, at the bottom of which a lot of mercury accumulated from the waste of a nearby plant. Mercury, cadmium, lead, copper, zinc, chromium, arsenic and other heavy metals not only accumulate in marine organisms, thereby poisoning marine food, but also have a detrimental effect on sea inhabitants. The accumulation coefficients of toxic metals, i.e. their concentration per unit weight in marine organisms relative to seawater, vary widely - from hundreds to hundreds of thousands, depending on the nature of the metals and the types of organisms. These coefficients show how harmful substances accumulate in fish, shellfish, crustaceans, planktonic and other organisms. The scale of pollution of sea and ocean products is so great that many countries have established sanitary standards for the content of certain harmful substances in them. It is interesting to note that with mercury concentrations in water only 10 times higher than natural levels, oyster contamination already exceeds the limits set in some countries. This shows how close the limit of sea pollution is that cannot be crossed without harmful consequences for human life and health.

2. Possible solutions

In order to avoid a water crisis, new technologies are being developed for water purification and disinfection, desalination, as well as methods for its reuse. However, in addition to scientific research, effective methods for organizing control over the water resources of countries are needed: unfortunately, in most countries, several organizations are involved in the use and planning of water resources (for example, in the USA, more than twenty different federal agencies are involved in this). This topic became the main topic for the March 19, 2007 issue of the scientific journal Nature. In particular, Mark Shannon and his colleagues from the University of Illinois at Urbana-Champaign (USA) reviewed new scientific developments and next-generation systems in the following areas: water disinfection and pathogen removal without the use of excessive amounts of chemical reagents and the formation of toxic by-products products; detection and removal of low concentration pollutants; reuse of water, as well as desalination of sea and inland water. Importantly, these technologies must be relatively inexpensive and suitable for use in developing countries.

2.1 Water purification

Disinfection is especially important in developing countries of Southeast Asia and Sub-Saharan Africa: it is there that pathogens living in water most often cause widespread illness. Along with pathogenic organisms such as helminths (worms), protozoa, fungi and bacteria, viruses and prions pose an increased danger. Free chlorine, the most common disinfectant in the world (as well as the cheapest and one of the most effective), works well against intestinal viruses, but is powerless against diarrhea-causing cryptosporidium C. parvum or mycobacteria. The situation is complicated by the fact that many pathogens live in thin biofilms on the walls of water pipes.
New effective disinfection methods must consist of several barriers: removal using physicochemical reactions (for example, coagulation, sedimentation or membrane filtration) and neutralization using ultraviolet light and chemical reagents. Relatively recently, visible spectrum light has again begun to be used for photochemical neutralization of pathogens, and in some cases, combining UV with chlorine or ozone is effective. True, this approach sometimes causes the appearance of harmful by-products: for example, the carcinogen bromate may appear from the action of ozone in water containing bromide ions.
In India, where the need for water disinfection is felt quite acutely, Javel water is used for these purposes.
In developing countries, technology is used to disinfect water in polyethylene terephthalate (PET) bottles using firstly sunlight and secondly sodium hypochloride (this method is used mainly in rural areas). Thanks to chlorine, it was possible to reduce the incidence of gastrointestinal diseases, but in areas where the water contains ammonia and organic nitrogen, the method does not work: chlorine forms compounds with these substances and becomes inactive.
It is expected that in the future, disinfection methods will include the action of ultraviolet radiation and nanostructures. Ultraviolet radiation is effective in combating bacteria living in water and protozoan cysts, but has no effect on viruses. However, ultraviolet light can activate photocatalytic compounds, such as titanium (TiO2), which in turn can kill viruses. In addition, new compounds, such as TiO2 with nitrogen (TiON) or with nitrogen and some metals (palladium), can be activated by radiation in the visible part of the spectrum, which requires less energy than irradiation with ultraviolet light, or even just sunlight. True, such disinfection installations have extremely low productivity.
Another important task in water purification is the removal of harmful substances from it. There are a huge number of toxic substances and compounds (such as arsenic, heavy metals, halogenated aromatic compounds, nitrosamines, nitrates, phosphates and many others). The list of substances suspected of being harmful to health is constantly growing, and many of them are toxic even in minute quantities. Detecting these substances in water and then removing them in the presence of other, non-toxic impurities, the content of which can be an order of magnitude higher, is difficult and expensive. And among other things, this search for one toxin may interfere with the discovery of another, more dangerous one. Pollutant monitoring techniques inevitably involve the use of sophisticated laboratory equipment and skilled personnel, so it is important to find inexpensive and relatively simple means of identifying contaminants wherever possible.
A kind of “specialization” is also important here: for example, arsenic trioxide (As-III) is 50 times more toxic than pentoxide (As-V), and therefore it is necessary to measure their content both together and separately for subsequent neutralization or removal. Existing measurement methods either have a low accuracy limit or require qualified specialists.
Scientists believe that a promising direction in the development of methods for detecting harmful substances is the method of molecular recognition motif, based on the use of sensor reagents (like litmus paper familiar from school), together with micro/nanofluidic manipulation and telemetry. Similar biosensor methods can be applied to pathogenic microorganisms living in water. However, in this case, it is necessary to monitor the presence of anions in the water: their presence can neutralize methods that are quite effective under other conditions. Thus, when treating water with ozone, bacteria die, but if there are Br- ions in the water, oxidation to BrO3- occurs, that is, one type of pollution changes to another.
Reverse osmosis system used in the USA: the water pressure on the side of the synthetic membrane where the pollutants are located exceeds the pressure of clean water on the opposite side. In accordance with the laws of hydrostatics, water seeps through the membrane, purifying itself onto the road. In general, there are two ways to combat harmful substances - influencing the micropollutant using chemical or biochemical reagents until it turns into a non-hazardous form, or removing it from the water. This issue is resolved depending on the location. Thus, Sono filtration technology is used in wells in Bangladesh, and reverse osmosis is used in factories in the USA to solve the same problem - removing arsenic from water.
Reverse osmosis system used in the USA: water pressure on the side of the synthetic membrane where the pollutants are located,
etc.................

Clean water problem. Natural water is not only a natural resource of enormous economic value, but also one of the most important components of ecosystems, and a habitat for aquatic plants and animals.

It would seem that the reserves of water on Earth are inexhaustibly large. However, in fact, the problem of the quantity and quality of water is becoming increasingly biocenotic and economically acute from year to year, and it is caused by the economic (and more often mismanagement) activities of people.

The volume of the entire hydrosphere of the Earth is 1,454,327,000 km 3. However, about 94% of it comes from the World Ocean, 4.12% from groundwater, 1.64% from glaciers, and only about 0.5% from lakes, rivers, soil moisture, and atmospheric water vapor. Consequently, fresh waters represent a negligible part of total water resources (Fig. 158).

Rice. 158. Volume of individual parts of the Earth’s hydrosphere and associated water of the earth’s crust (including water of living organisms) (in thousand km 3) (according to: Blagosklonov et al., 1967).

River water, in which we are particularly interested, accounts for less than one millionth of the volume of the hydrosphere. Its very important property is a high degree of mobility and the ability to quickly renew itself. Water in river beds changes on average every 12 days, or 30 times during the year.

Meanwhile, in other bodies of water, complete exchange occurs much more slowly: in lakes, after about 10 years.

The extremely uneven distribution of water on Earth is very important. In addition, most of it is unsuitable for use by plants, animals, and humans. Meanwhile, water consumption is increasing from year to year, because modern industry requires a huge amount of water, not counting what is consumed by agriculture and the population for their own needs. Let us note, for example, that to produce 1 ton of paper, 36 tons of water are required, for the same amount of nitric acid - 300 tons, synthetic fiber - 3500 tons of water. A metallurgical plant, like Magnitogorsk, consumes about the same amount of water as a city with a million people. However, one must keep in mind that, for example, 500 tons of water are consumed to produce 1 ton of grain. It is estimated that by 1980 the water demand in the Soviet Union will reach levels almost equal to the steady flow of our rivers. At the same time, industry and public utilities absolutely need clean water, and some industries need such clean water as is available only in Baikal.

Unfortunately, with such a great need for water, it is often used very irrationally. Thus, in one of the irrigation systems of Tajikistan, filtration takes away about 63% of the water entering it.

In many countries there is already a shortage of fresh water, complex technological, economic, and at the same time biogeocenological problems arise. It is clear that all of them taken together are of direct importance for wildlife and for humans. Deforestation near rivers and at their sources, plowing up the slopes of valleys and floodplains, straightening riverbeds, indiscriminate drainage of high-moss bogs and other insufficiently thought-out measures have a sharply negative impact on the condition of rivers and other fresh water bodies, causing their shallowing, a decrease in reserves and groundwater levels, drying out of soils.

The quantitative shortage of fresh water is aggravated by a sharp deterioration in its quality due to the discharge of untreated or poorly treated industrial, agricultural and other wastewater directly into rivers and lakes, as well as into groundwater. In recent years, 16 billion m3 of wastewater annually entered the reservoirs of the RSFSR, of which only 4.5 billion m3 was treated. Meanwhile, it is known that every cubic meter of wastewater contaminates 40-60 times the volume of clean water.

Waste from chemical and oil refineries is especially dangerous. Even their cleaning does not completely remove the threat to water bodies, since the most advanced treatment methods do not provide a complete guarantee; 10-20% of the most persistent pollutants, including all water-soluble salts, remain in wastewater.

The task of combating detergents that have entered water bodies, i.e., cleaning chemicals used in industry and households, is very difficult. They cover the surface of the water with a thick layer of foam and are very difficult to destroy.

All this waste causes mass death of aquatic plants, invertebrates and fish, making water unfit for consumption. Ultimately, such reservoirs will suffer the tragic fate of North American Lake Erie, which has turned into a dead lake.

In the last 20-30 years, a lot of waste containing nitrogen and phosphorus compounds has been entering water bodies. As a result, anthropogenic eutrophication of such reservoirs occurs, i.e., an exorbitant increase in productivity. It is caused mainly by chemical fertilizers from surrounding fields being washed into water bodies. Eutrophication entails the increased development of some hydrobionts, in particular phytoplankton (which causes “blooming” of water), coastal thickets, algae, etc. The deep zone expands with anaerobic metabolism, accumulation of hydrogen sulfide, ammonia, etc. Redox processes are disrupted and a deficiency occurs oxygen. All this is followed by the death of valuable fish species, the water becomes unsuitable not only for drinking, but even for swimming. Ultimately, such a eutrophicated reservoir loses its economic and biogeocenotic significance.

The struggle for clean water has become one of the most pressing problems of the entire range of environmental protection problems. Without going into details, we will note some basic methods. The most effective of them must be a categorical ban on discharging wastewater into water bodies without preliminary treatment. Unfortunately, such a recommendation in its absolute terms is impossible. In its place, proposals were made, for example, to discharge wastewater away from water bodies. In some southern regions, it was proposed to collect wastewater in estuaries in winter, and use it to irrigate fields in summer. However, irrigation is not necessary everywhere and not all types of wastewater are suitable for it. The advice to pump wastewater under high pressure into underground workings cannot be accepted unconditionally, since this creates a real danger of polluting artesian waters, which are extremely necessary for local domestic and industrial needs.

Therefore, the most common way remains - purification of drained water by physical, chemical or biological methods. The simplest example of the first of them is the so-called oil traps. In them, the admixture of oil in the water is mechanically retained, precipitated and in this way excluded from the further circulation. Good results are achieved by a more complex method of electrocoagulation.

Much more complicated is chemical purification, in which substances dissolved in water are precipitated in one way or another and then removed by settling. Chemical cleaning is widespread, but does not always lead to the expected result. In particular, detergent residues, which now flow in large quantities through sewers into water bodies, cannot be treated chemically.

Biological and biochemical treatment is very promising. It consists in the fact that the mineralization of harmful impurities is carried out by microorganisms. The mineralization process takes place either in the soil or in special reservoirs, under conditions close to natural or artificially created. In this case, different types of treatment facilities are used. Previously, preference was given to biological ponds, irrigation fields, and filtration fields, but this way wastewater is purified very slowly. Therefore, biological filters and aeration tanks are now more often used. The latter look like containers open at the top, where waste liquid enriched with microorganisms moves slowly.

Of great importance is the constant improvement of production technology in order to minimize the loss of raw materials, production waste, etc. It is very promising to introduce closed cycles of water use into factory practice, when water received from outside and used for the manufacture of products is not thrown away outside, but undergoes thorough cleaning and is reintroduced into the technological process at the same plant. This technique allows you to achieve great savings in water consumption and avoid its pollution outside the enterprise. It is successfully used at a number of our enterprises, as well as in other countries, especially in Japan, where there is an acute shortage of fresh water.

Currently, construction and improvement of treatment facilities is being carried out incomparably more energetically than in the recent past. Unfortunately, they are very expensive, are built slowly and are still far from being properly effective. Until now, treatment plants are often put into operation very late, and the environment suffers serious damage from waste from industrial enterprises and populated areas.

In timber production areas, noticeable damage to rivers, lakes and their fauna is caused by improperly organized timber rafting. Mol alloy has a particularly detrimental effect on water bodies when the trunks are fused without preliminary rafting, and so to speak in bulk. At the same time, many logs dry out along the banks or drown, the water becomes clogged with rotting bark and is poisoned by chemicals released from the bark and wood. Currently, moth rafting is prohibited, rafting rivers are gradually cleared of accumulated “float”, and ultimately the regime of such reservoirs is improving. However, all these activities are still far from complete and are being implemented too slowly.

During heavy rains and when snow melts in agricultural areas, mineral fertilizers and pesticides are intensively washed from fields into rivers and lakes, which leads to contamination of water bodies with harmful chemicals. In addition, at the same time, the rivers become clogged with soil particles washed away from the fields and, accordingly, become shallow. According to the Committee on the Desna, in the Bryansk region alone every year, stormy streams carry away about 3 million cubic meters of land. Of course, it is dominated by sand and clay, but at the same time there are thousands of tons of fertile soil.

Tree and shrub plantings in floodplains, on the slopes of river valleys and in the catchment area, as well as preserved forests that require careful treatment, can serve as protection against these phenomena. Thanks to them, surface runoff is sharply reduced, becomes more uniform throughout the year, rivers stop shallowing and the water level in them becomes more stable. This is also facilitated by the cessation of continuous plowing of floodplain lands and straightening of river beds.

Particularly important is the issue of protecting the World Ocean and seas. Many of these waters serve as places for uncontrolled dumping of all kinds of waste. The famous traveler Thor Heyerdahl, crossing the Atlantic Ocean, observed with alarm that even its central parts were extremely clogged with all kinds of garbage and waste.

Ocean tankers annually transport hundreds of millions of tons of oil and various petroleum products. Numerous ships use liquid fuel. Sometimes their engines are not adjusted well enough and some of the fuel ends up overboard. On the high seas, despite international agreements, tankers often wash out their empty tanks, and large quantities of oil end up in the water. Huge disasters are caused by accidents of giant supertankers, when a mass of oil erupts, which in a continuous layer covers the surface of the water and the edge of the shore and destroys a mass of aquatic plants, invertebrates, fish, and seabirds (Fig. 159). In this case, even many land birds die, and later their eggs.

Rice. 159. Black scoter dying from oil. Photo by R. Rode.

Of course, the strictest adherence to generally accepted rules regarding places and methods of washing tankers and other vessels is necessary. The development and improvement of methods for the accelerated and complete destruction of spilled oil, especially in the event of supertanker accidents, deserve special attention.

It is completely unacceptable, as some Western countries practice, to dump industrial waste containing dangerous poisons, poisonous and radioactive substances in the depths of the ocean in containers. Sooner or later, both metal and reinforced concrete containers collapse and their contents end up in the water. Meanwhile, sea water, even at the greatest depths, is gradually drawn into currents and, being contaminated with toxic waste, becomes extremely dangerous for marine organisms and for people in contact with the ocean and aquatic organisms.

Scientists around the world say that the world is experiencing an increasingly acute shortage of fresh water. But how does this happen? After all, logically, there is a water cycle in nature, which means, theoretically, the amount of water on the planet does not change.

However, the problem of fresh water exists. But it doesn’t take much to solve it. If every person on the planet adhered to simple rules of water conservation in everyday life, the problem of its shortage would not be felt so acutely. But not only people, but also businesses should save. Scientists have calculated that over the 20th century, fresh water consumption increased sevenfold, while the planet's population only tripled. The reason for this is the rapid growth of industry. If enterprises used water more economically in production, strictly monitoring leaks and gusts, purifying water as much as possible and returning it back to nature, the problem of water shortages would disappear for at least a hundred years.

Every person can make their own contribution to saving water. You don't need to put in a lot of effort to do this. Just follow the rules given in this article.

"Perpetual motion machine"

Water on Earth is unique. After all, only this substance is on our planet simultaneously in three of its forms: in liquid, solid and gaseous form. Moreover, water constantly remains within a cycle, which is called the “water cycle in nature.” Thus, water on Earth is constantly being reused.

The water cycle in nature looks very simple. The sun heats the water in rivers, lakes, and oceans and turns it into steam. Water also evaporates from the soil, tree leaves and other places. The steam rises into the air and condenses into clouds. Interestingly, clouds are made of small drops of water. When these drops become heavy and can no longer be held in the air, they fall to the ground in the form of rain. If the air temperature is below zero at that time, it will be in the form of hail or snow. Rainwater saturates the earth, rivers, lakes, seas, oceans and other bodies of water with water. Some of the water seeps under the top layer of soil and forms so-called groundwater - aquifers. After this, the water cycle cycle begins again.

How much water is there in the world?

Scientists estimate that about 75% of the surface of our planet is covered with water. The volume of the World Ocean is 1.3324 billion cubic meters of water. But only 1% of the total water on Earth is available for human use. The rest is either salty water of the seas and oceans, or frozen in polar glaciers and mountain ice caps.

Interestingly, the amount of water on Earth is relatively static. Moreover, during the cycle the water is purified. After all, steam evaporates, that is, fresh water without impurities. The question arises: if water does not disappear from the Earth, but simply goes through a circulation cycle and, moreover, is purified at the same time, then why is there less of it? Why is there so much talk about the problem of fresh water shortage? Why do environmentalists call for saving water? The answer is simple - people use up fresh water faster than nature can replenish them naturally. In addition, technological progress and an increase in the number of people on Earth leads to an increase in water use. It is estimated that water consumption increases by seven percent every year. At the same time, fresh water is distributed unevenly on the planet, and for many people it is not just a “convenience”, but a very scarce and necessary substance. Moreover, not only people, but also fish and other animals suffer from a lack of fresh water. They do not have a tap from which water flows. And the intensive use of water from rivers and other bodies of water leads to a decrease in their level and even drying out.

help yourself

By using water wisely, we help nature, and therefore ourselves. If we save water, it means we consume less of it and more water remains in wells, rivers or other places from where it is extracted for our needs. If we save water, we save energy. After all, the water supplier will need to spend less energy to supply water to our home and to further purify the wastewater. By reducing the use of hot water, we save twice as much - we do not spend energy on heating it. And needless to say, by saving water, we save, first of all, our money. Which can be spent on other needs.

Scientists estimate that the average person in a typical country where water is available uses about 200 liters of water per day. However, for example, in the USA this figure is 280 liters, and in Germany – 140 liters. In megacities, much more water is consumed than in small towns and villages. For example, in Moscow, on average, one person consumes up to 400 liters of water per day. It's actually a lot. Especially if you look at how people usually use water.

For normal functioning of the body, each person needs to drink about 2-3 liters of liquid per day. But where do the remaining 197 liters go? A person also spends water on visiting the toilet, taking a bath and shower, washing clothes, washing hands, washing dishes, cooking, cleaning and other needs. And the water that people supposedly use is not actually used. It is consumed in the form of various types of leaks.

How to save water?

There are several very simple, but very effective ways to save water.

1. Hand washing. It is known that washing hands requires water. But while soaping them, water simply flows from the tap and is not used. To prevent it from being wasted, after you have wet your hands, you must first turn off the water and then take the soap. But many will argue that unscrewing the tap with soapy hands is not convenient. Perhaps, but for convenience, there are also faucets with a lever, as well as faucets with motion detectors that automatically turn off the water if you remove your hands.

2. Brushing your teeth. If you turn off the water when you brush your teeth, you will save at least 4 liters of water per minute. Considering that the process of brushing your teeth takes 2-3 minutes, that’s 8-12 liters just at one time! Simple mathematics will help you calculate that if you listen to your dentist’s advice and brush your teeth twice a day, then simply turning off the water during brushing will save at least 16 liters of water per day. This amounts to 480 liters of water per month!

3. Small trash. We also save water by not clogging the toilet! It is better to throw paper, insects, hair and other small debris in the trash rather than flush it down the toilet. This way you reduce the load on the wastewater treatment system.

4. Washing dishes. It's time to join the “clean plate society”! After all, the cleaner the plate, the less water is spent on washing it. It is also more economical to wash dishes using a dishwasher rather than by hand. Of course, if you use it at full load.

5. Swimming. Take baths less often. But when taking a shower, reduce the water pressure. This way you can save up to 1000 liters of water per month!

6. Leaks and bursts. Check your taps and pipes for leaks and if any are found, get rid of them. Even small leaks can waste up to 300 liters of water per month!

By the way, a small leak in the toilet can cost you about 600 liters of water per month! Therefore, check your toilet for the slightest leaks. They are not always noticeable, but there is an easy way to spot them. Remove the lid of the reservoir and add food coloring to the water. Wait a few minutes. And if the toilet bowl becomes stained, then there is a leak and it must be repaired immediately.

7. Washing. You also need to know how to do laundry. Make sure your clothes are truly dirty before you put them in the laundry basket. Wash only when the machine is fully loaded and, if possible, use economical washing modes.

8. Watering plants. If you have a garden, vegetable garden or lawn near your home, do not water it every day. Plants feel good even if watered once every 3-5 days. Also make sure that you are watering the plants, and not the sidewalk, fence, paths and... neighbors or passers-by.

9. Cleaning. The temptation to wash away dirt from the floor, stairs, porch or terrace with just a strong stream of water is great. But refrain from it and use a broom or broom, and then wash it with a mop.

And if you need to wash your car, turn off the water in the hose when you soap the car. This way you will save over 100 liters of water.

What's next?

All over the world, scientists are exploring various options for how to use water more efficiently, how to avoid leaks and reduce waste to zero. So far, most of them are inclined to believe that the best way to save water for domestic needs is to abandon its centralized supply. In China, Spain, Brazil and some other countries, projects to create private water supply systems are already being implemented. It is expected that this will reduce water consumption by more than half - to 90-120 liters per person per day.

Some countries that have direct access to the sea or ocean are implementing projects to desalinate salt water. Water desalination is especially active in the Persian Gulf countries. At the moment, desalination costs from $2.5 to $4.5 per cubic meter of fresh liquid. But environmentalists warn that mass desalination of water is not the solution. After all, this can lead to disruption of the ecological balance in the seas and oceans.

Therefore, before turning on the tap, think about it: do you really need to use water here and now?