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Acid rain is a mixture of materials, both wet and dry, that fall to the earth from the atmosphere. They contain elevated levels of nitric and sulfuric acids. In simple terms, this means that the rain becomes acidic due to the presence of pollutants in the air. The air changes its composition due to emissions from machinery and production processes. The main component of acid rain is nitrogen. Acid rain also contains sulfur.
The combustion of fossil fuels and industry, which primarily emits nitrogen oxides (NOx) and sulfur dioxide (SO2), are causing irreversible changes in the atmosphere. Acidity is determined based on the pH level in the water droplets. Normal rainwater is slightly acidic with a pH range of 5.3-6.0. Carbon dioxide and water present in the air together react to form carbonic acid, which is a weak acid. When the pH level of rainwater falls below this range, the aforementioned precipitation forms.
When these gases react with water and oxygen molecules, sulfuric and nitric acids are formed, among other chemicals found in the atmosphere. They are also called chemical compounds of medium acidity. They usually lead to weathering of matter, corrosion of metal, and peeling of paint on the surface of buildings.
Volcanic eruptions also contain certain chemicals that can cause acid rain. In addition, the burning of fossil fuels, the operation of factories and vehicles as a result of human activities also lead to an increase in the acidity of formations in the atmosphere.
Currently, large amounts of acid precipitation are observed in Southeastern Canada, the Northeastern states of America and most European countries. Russia, Sweden, Norway and Germany suffer greatly from them, at least that’s what impartial statistics say. In addition, acid precipitation has recently been observed in South Asia, South Africa, Sri Lanka and South India.
Forms of precipitation
Acid precipitation comes in two forms
- wet
- dry
Each of them affects the earth's surface differently. And each of them consists of a variety of chemical elements. It is believed that dry forms of precipitation are more harmful, since they spread over vast distances, often crossing not only the borders of cities, but also states.
Wet precipitation
When the weather is humid, acids fall to the ground in the form of rain, sleet, or fog. The climate adjusts, driven by the need to respond. Acids are removed from the atmosphere and deposited on the earth's surface. When acid reaches the ground, it negatively affects a wide range of animal, plant and aquatic life. The water enters rivers and canals, which mix with seawater, thereby affecting marine habitats.
Dry precipitation
It is a mixture of acidic gases and particles. About half of the acidity in the atmosphere falls back to earth through dry deposition. If the wind blows in areas where the weather is dry, acidic pollutants turn into dust or smoke and fall to the ground as dry particles. These substances have a negative impact on cars, houses, trees and buildings. Almost 50% of acidic pollutants from the atmosphere are returned through dry precipitation. These acidic pollutants can be washed off the surface of the earth by rainfall. Then the level of acidity of water resources increases even more.
If wet precipitation sooner or later evaporates back into the atmosphere, then in forests dry precipitation clogs the pores of tree leaves.
Story
Acid rain and interesting facts about it have been known for quite some time. Acid rain was first mentioned back in the 1800s, during the Industrial Revolution. Scottish chemist Robert Angus Smith was the first to report this phenomenon in 1852. He devoted his life to researching the connection between acid rain and air pollution in Manchester, England. His work only came to public attention in the 1960s. The term was coined in 1972 when The New York Times published reports on the effects of climate change on forest growth.
Acid precipitation is a source of both natural and man-made disasters. But here the opposite effect occurs. It is these disasters that are most often the sources of acid rain. The main reason for this is the combustion of fossil fuels, which is accompanied by emissions of sulfur dioxide (SO2) and nitrogen oxides (NOx) into the atmosphere.
Natural springs
Natural sources of problematic precipitation:
- The main natural cause of acid rain is volcanic emissions. Volcanoes emit acid-forming gases that create abnormal acidity. Against this backdrop, record amounts of precipitation fall. The earth suffers from phenomena such as fog and snow. Vegetation and the health of residents in the vicinity of volcanic formations suffer.
- Rotting vegetation, forest fires and biological processes in the environment generate acid rain by forming gases.
- Dimethyl sulfide is a typical example of the main biological sources of sulfur-containing elements in the atmosphere. It is its emissions that react with water molecules using electrical activity. Nitric acid becomes acid rain.
Technogenic sources
Human activities leading to the release of chemical gases such as sulfur and nitrogen are the main cause of acid rain. It is we, people, who are to blame for the fact that the atmosphere is destroying the planet. These activities are associated with sources of air pollution. It is the consequences of man-made activities that lead to emissions of sulfur and nitrogen from factories, energy facilities and cars. In particular, the use of coal for electricity generation is the largest source of gaseous emissions that lead to acid rain.
Cars and factories also release large amounts of gaseous emissions into the air. The scary thing is that this process repeats itself daily, especially in industrialized areas of the city with a lot of car traffic. These gases react in the atmosphere with water, oxygen and other chemicals to form various acidic compounds, such as sulfuric acid, ammonium nitrate and nitric acid. These experiments result in extremely high amounts of acid rain.
Existing winds carry these acidic mixtures over large areas across borders. They fall back to earth in the form of acid rain or other forms of precipitation. Having reached the ground, they spread over the surface, absorbing into the soil and ending up in lakes, rivers and finally mixing with sea water.
The gases sulfur dioxide (SO2) and nitrogen oxides (NOx) are mainly derived from electricity through the combustion of coal and are the cause of acid rain.
Consequences of acid rain
Acid rain has significant impacts on the environment and public health. The impact on the aquatic environment is very high. Acid rain either falls directly onto bodies of water or flows through forests, fields and roads into streams, rivers and lakes. Over a period of time, acids accumulate in the water and lower the pH level. Aquatic plants and animals require a certain pH level. It needs to stay around 4.8 to survive. If the pH level drops below, conditions become hostile to the survival of aquatic organisms.
Acid rain tends to change the pH and concentration of aluminum. This greatly affects the pH concentration level in the surface layer of water, thereby affecting fish as well as other aquatic life forms. When the pH level is below 5, most eggs will not hatch.
Below levels can also kill adult fish. Sediment from watersheds that is discharged into rivers and lakes reduces biodiversity in rivers and lakes. The water becomes more acidic. Many species, including fish, plants and various insects in lakes, rivers and streams, have become sick and some have even been eliminated entirely due to excess acid rain entering water resources.
Politicians, scientists, environmentalists and researchers are ringing the bells in an attempt to educate people about the harm of acid rain. Unlike wet precipitation, dry precipitation is more difficult to measure. When acid deposits, harmful organisms from the surface of the earth are washed into lakes and streams, which can cause uncontrollable climate change.
Hydrometeors with a pH below normal and characterized by the presence of harmful substances are acid rain. It could be snow, fog, rain or hail. Any of the species in the atmosphere and on earth can lead to an environmental disaster.
Just a couple of decades ago, only the scientific community was concerned about the negative impact of this phenomenon. Now it is causing great concern not only in the scientific world, but also among the general public, as well as various government agencies.
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History of the problem
The effect of precipitation with a reduced water index on the environment was outlined more than a hundred years ago by the British chemist R. Smith. The scientist became interested in smog and the substances in its composition. Thus was born the concept of acidity, which was immediately rejected by the advanced scientific community of the time. Ten years later, his colleague started talking about the hydrogen index again.
The chemist and engineer S. Arrhenius published a report on chemical substances that can release hydrogen cation. He again drew the attention of scientists to the harmfulness of such precipitation, to the danger the phenomenon poses, and became the person who coined the term: acid/base. Since then, these indicators have been considered the level of acids in the aquatic environment.
Svante Arrhenius
The main elements of hydrometeors are acidic components. This substance is monobasic acids (sulfuric and nitric). Precipitations based on interacting gases (chlorine and methane) are less common. What their composition will be depends on what chemical waste is combined with water.
In short, the mechanism of formation of the phenomenon is the combination of oxides released into the atmosphere with water molecules. During the interaction, the formation of chemical components occurs - sulfuric and nitric acid.
Reasons for appearance
Hydrometeors with low pH levels are caused by increased concentrations of sulfur and nitrogen oxides in the atmosphere. Compounds enter the atmosphere either naturally or man-made. Natural sources are:
The main reason is human activity. What is it? The factor causing precipitation is air pollution. The most famous pollutants are road transport and thermal power plants. A significant role in the appearance of oxides in the atmosphere is played by emissions from industrial enterprises and nuclear tests. Hydrometeors with acid are formed in large quantities in places where space rockets are launched.
Vostochny Cosmodrome. Launch of the Soyuz-2.1b launch vehicle with 19 satellites Hydrometeors with acids are not only snow or fog, but also dust clouds. They are formed when toxic gases and vapors rise into the air during dry weather.
The main reasons lie in the huge emissions of harmful substances into the atmosphere. The main ones here include chemical production, oil and gasoline storage facilities, and solvents, which are used by enterprises and in everyday life more and more actively every year. The problem of acid precipitation is very acute in areas where metal processing is concentrated. Production leads to the appearance of sulfur oxides in the atmosphere, which cause irreparable damage to flora and fauna.
Of all the above, the greatest danger is the phenomenon associated with atmospheric pollution by toxic waste from internal combustion engines. Gases rise into the air and cause oxidation. One of the reasons is nitrogen compounds released during the production of materials for construction, building construction, and road construction. They also often result in sediments with low pH.
Interesting Facts:
- On Venus, smog is caused by the concentration of sulfuric acid in the atmosphere.
- On Mars, limestone and marble rocks are also corroded by toxic acid fallout in the form of fog.
The facts about such precipitation show that the problem of acid rain has existed for millions of years. Their influence has been known on Earth since prehistoric times. Nearly 300 million years ago, the formation of acid rain led to the extinction of 90 percent of species.
Consequences for nature
Precipitation with low pH levels poses a risk of global disturbances in the biosphere. What harm do they cause? Ecologists talk about the negative consequences of this precipitation:
Consequences for modern humanity
Unfortunately, the substance that makes the greatest contribution to the formation of acid precipitation is only increasing in the atmosphere every year. Acid rain as a global environmental problem has become clear and serious. Their most frequent formation is observed in Denmark, Sweden, Norway and Finland. Why do the Scandinavian countries suffer more than all others? There are several reasons for this. Firstly, wind transport of sulfur formations from Central Europe and Britain. Secondly, lakes poor in limestone contribute to acid rain. Reservoirs do not have much ability to neutralize acids.
In Russia, acid precipitation is increasing every year. Environmentalists are sounding the alarm. The atmosphere over megacities is oversaturated with chemical elements and dangerous substances. Acid rain and smog occur especially often over large cities in calm weather. In the Arkhangelsk region, acid precipitation is caused by the combustion of low-quality fuel. The problem of environmental pollution in the Arkhangelsk region has not changed for the better for the last ten years and is caused by emissions of chemicals into the atmosphere. These are sulfuric and nitric acids, leading to the formation of acid precipitation. The situation in Kazakhstan is not the best. There, acid precipitation is associated with the development of mining deposits and the activities of large test sites.
Negative consequences as a result of acid rain are observed in all countries without exception. As a result of their loss, not only the environment suffers. Chronic diseases such as allergies and asthma are becoming more acute among the population. The problem is becoming more acute because it has a great negative impact on the health of modern people. It has been scientifically proven that they cause an increase in the number of cancer tumors. The main cause of precipitation is harmful emissions, which humans are unable to avoid. This is why doctors advise against getting out in the rain, protecting yourself with raincoats and umbrellas, and washing thoroughly after a walk. The consequences can be intoxication and the gradual accumulation of toxins in the body.
Children, young people and older people suffer from allergies and asthma If you ask the question: name the areas where acid rain most often forms? The answer is quite simple: in places with the greatest concentration of various industries and vehicles. However, identifying a top region in this regard is not so easy. Why is acid rain dangerous? Because due to the wind changing its direction, precipitation can fall many kilometers from a metropolis or test site.
Control measures
The causes of acid precipitation have been studied quite fully. Despite this, the problem of acidic hydrometeors is only growing. Much has been said about how to combat acid rain, but the scale of the environmental disaster is only increasing in scale. Examples of solving the problem are demonstrated in many developed countries.
Acid rain as a global environmental problem, along with such a problem as ozone holes, does not have a radical and quick solution. Many scientists and environmentalists believe that due to the development of modern economics, this is completely impossible to do. To the question: explain, provide evidence, they present graphs and tables of studies that indicate an increase in the degree of danger to nature and humans. Now the solution to the problem is to reduce harmful emissions. The cause of the negative phenomenon must be eliminated. To do this, the following methods of combating acid rain are used:
- reducing the sulfur content in fuel reduces the causes of acid precipitation;
- the operation of high pipes in enterprises represents modern ways to solve the problem;
- improved technology eliminates the causes and consequences of harmful emissions;
- Liming of reservoirs is also an effective way to solve the problem.
It is worth noting that there is still not even a hint that in the foreseeable future methods will be created to minimize the negative impact of acid precipitation on humans and nature.
Acid rain is one of the main threats of our time, resulting from human economic activity.
We have already touched on this topic in our material - ACID RAIN IS THE ENEMY OF ALL LIVING THINGS. In this material we will provide several precise definitions given to this phenomenon in respected dictionaries and encyclopedias.
Acid rain is...
Dictionary COUNTRIES OF THE WORLD
Acid rain, a term used to describe the deposition of chemical pollutants in the form of either particulate matter or acid rain, hail, snow or fog. Automobiles, industrial production processes, and the burning of fossil fuels in power plants create pollution primarily in the form of sulfur dioxide, nitrogen oxides, and hydrocarbons that react with water and sunlight to form weak sulfuric or nitric acid, ammonium salts, and others. mineral acids. All this is deposited on the ground, often at a great distance from the source of the release, causing corrosion, death of trees, unwanted acidification of water and soil, and therefore a threat to human health. The degree of acidity is usually measured using the pH scale, a logarithmic system for measuring the concentration of hydrogen ions. The amplitude of values is from 0 (maximum acidity) to 14 (maximum alkalinity). pH value = 5.6 corresponds to pure water.
Countries of the world. Dictionary. 1998
Peoples and cultures. Oxford Illustrated Encyclopedia
Acid rain, chemical pollution of water resources, flora and fauna caused by the emission of exhaust gases as a result of the combustion of fossil fuels. The acidity of rain, snow and fog increases due to the absorption of exhaust gases, mainly sulfur and nitrogen oxides emitted by power plants, factories and road transport. Cauldrons cause damage to human health, causing bronchial diseases, destroying limestone buildings, and increasing the acidity of lakes and rivers, which is fatal to fish, animals, vegetation, and forests. Acidic waters are also dangerous because they contain harmful metals, such as cadmium and mercury, which are usually retained in the soil. The alarm about the effects of KD was first raised in Sweden in the 1960s; from them, of course, it means that part of the forests of Europe, globally, suffered. Central, as well as S., E. and N.-E. USA and Japan. In 1984, pl. countries signed a protocol to the Geneva Convention on the Control of Air Pollution (1979), agreeing to reduce sulfur emissions, although the worst air polluters - the UK, the USA, Poland and Spain - did not sign on to this document. Significant reductions in sulfur emissions require the reconstruction or closure of coal-fired power plants. Reducing nitrogen oxide levels can be achieved by reducing the life and speed of passenger car and truck engines and equipping them with catalytic converters that remove most of this gas (and hydrocarbons that contribute to the formation of nitrogen) from automobile exhaust; since 1992, the installation of catalytic converters has been mandatory in European countries; in the US they have been widely used to control air pollution since the 1970s.
Peoples and cultures. Oxford Illustrated Encyclopedia. - M.: Infra-M. Edited by R. Hoggart. 2002
ACID RAIN (acid rain), characterized by an increased content of acids (mainly sulfuric acid); pH value<4,5. Образуются при взаимодействии атмосферной влаги с транспортно-промышленными выбросами (главным образом серы диоксид, а также азота оксиды и др.). Вредно действуют на здоровье людей, растительный и животный мир, сооружения и конструкции; закисляют почвы и водоемы. Распространены в промышленных районах США, стран Западной Европы, России и др. Кислотные загрязнения могут содержаться в других атмосферных осадках (снег, град и т.п.).
Modern encyclopedia. 2000
Ecological dictionary
Acid rain is rain caused by atmospheric pollution with sulfur dioxide (SO 2). They have a biocidal effect, in particular, the death of fish (for example, in the waters of Scandinavia due to the transfer of gas emissions in the industrial cities of England).
Ecological Dictionary. - Alma-Ata: “Science”. B.A. Bykov. 1983
Geography. Modern illustrated encyclopedia
Acid rain is one of the types of intense environmental pollution, which is the precipitation of drops of sulfuric and nitric acids with rain, resulting from the reaction of sulfur and nitrogen oxides emitted into the air by industrial enterprises and transport with water droplets in the atmosphere. Acid droplets can be carried long distances by air currents before falling as acid rain. Acid rain causes great damage to forests, water bodies, crops, buildings, etc., and also adversely affects human health. Acid rain is heaviest in and near the world's most industrialized areas. In 1984, in the Black Forest (Germany), about half of the trees in the forests were damaged by acid rain. Significant damage to forests has also been observed in the northeastern states of the United States and Eastern Canada. To overcome the adverse effects of acid rain, national and international standards are being set to reduce nitrogen and sulfur emissions into the atmosphere.
Geography. Modern illustrated encyclopedia. - M.: Rosman. Edited by Professor A.P. Gorkin. 2006
As we can see from the above definitions, acid rain is not a local problem of individual industrial areas of our planet. The damage caused by such rains is global in nature and requires appropriate global solutions. To be more precise - active global solutions, since such damage is often irreparable / irreparable.
Normal rainwater has a slightly acidic reaction, since the air where moisture particles are formed contains carbon dioxide. But if the atmosphere is high in pollutants emitted by cars, metallurgical plants, power plants and other human activities, then the water reacts with these compounds and its pH decreases. It contains sulfuric, nitrogenous, sulfurous, nitric and other acids. And when they fall on the ground in the form of rain, snow or other types of precipitation (including fog), these substances interact with the environment and have a detrimental effect on it.
Consequences of acid rain
If acid rain is observed in the area of reservoirs - over rivers, lakes, seas, then the water in them also gradually begins to oxidize, although with small impacts it actively resists changes in pH. But if acid rain occurs regularly, then this stability decreases, as a result, the ecological condition of water bodies deteriorates. With a high concentration of acids in water, the creatures living in it, most often insects, begin to die. For example, mayflies cannot live at a pH greater than 5.5. Fish are more resistant to such pollution, but if the insects die, the chain is inevitably broken: for example, trout that feed on these are faced with a lack of food. As a result, the number of fish in the reservoir also decreases.
Some fish can exist in acidic water, but cannot raise offspring in it, which also leads to the death of the population.
When acid rain falls on forests, tree leaves are destroyed and fall off. Most often, tall trees that find themselves in acidic clouds are exposed to this effect. Light precipitation with high acidity destroys forests more slowly and imperceptibly: they gradually reduce soil fertility and saturate it with toxins, plants begin to get sick and slowly die out.
Cars that cause air pollution then begin to suffer from them: acid precipitation destroys their protective coatings. Such rains are no less dangerous for structures created by man: buildings and monuments made of marble or limestone are literally corroded, as calcite is washed out of them.
Granite and sand rocks are more resistant to acids.
Acid rain also poses a threat to human health. Outwardly, they are impossible to distinguish, they look like ordinary rain, do not have a specific smell or taste and do not lead to unpleasant sensations on the skin. You can be exposed to acids not only during precipitation, but also while swimming in a river or lake. This leads to an increased risk of cardiovascular diseases and respiratory diseases - asthma, bronchitis, sinusitis.
Atmospheric pollution with compounds of sulfuric and nitric acids followed by precipitation is called acidicrains. Acid rain is formed as a result of the release of sulfur and nitrogen oxides into the atmosphere by enterprises of the fuel and energy complex, motor vehicles, as well as chemical and metallurgical plants. When analyzing the composition of acid rain, the main attention is paid to the content of hydrogen cations, which determine its acidity (pH). For pure water, the pH value is pH = 7, which corresponds to a neutral reaction. Solutions with a pH below 7 are acidic, above - alkaline. The entire acidity-alkalinity range is covered by pH values from 0 to 14.
About two-thirds of acid rain is caused by sulfur dioxide. The remaining third is caused mainly by nitrogen oxides, which also serve as one of the causes of the greenhouse effect and are part of urban smog.
Industry in different countries annually emits more than 120 million tons of sulfur dioxide into the atmosphere, which, reacting with atmospheric moisture, turns into sulfuric acid. Once released into the atmosphere, these pollutants can be carried by the wind thousands of kilometers from their source and return to the ground in rain, snow or fog. They turn lakes, rivers and ponds into “dead” bodies of water, destroying almost all living things in them - from fish to microorganisms and vegetation, destroying forests, destroying buildings and architectural monuments. Many animals and plants cannot survive in highly acidic conditions. Acid rain not only causes acidification of surface waters and upper soil horizons, but also spreads with downward flows of water throughout the entire soil profile and causes significant acidification of groundwater.
Sulfur is found in minerals such as coal, oil, copper and iron ores, some of which are used as fuel, while others are processed in the chemical and metallurgical industries. During processing, sulfur is converted into various chemical compounds, among which sulfur dioxide and sulfates predominate. The resulting compounds are partially captured by treatment devices, and the rest is released into the atmosphere.
Sulfates are formed during the combustion of liquid fuels and during industrial processes such as oil refining, the production of cement and gypsum, and sulfuric acid. When burning liquid fuels, about 16% of the total amount of sulfates is formed.
Although acid rain does not cause global problems such as global warming and ozone depletion, its impact extends far beyond the country where it produces the pollution.
Acid rain and ponds. As a rule, the pH of most rivers and lakes is 6...8, but with a high content of mineral and organic acids in their waters, the pH is much lower. The process of acid rain entering water bodies (rivers, ponds, lakes and reservoirs) includes many stages, at each of which their pH can decrease or increase. For example, changes in the pH of sediments are possible when they move along the forest floor, interacting with minerals and products of microorganisms.
All living things are sensitive to changes in pH, so increasing the acidity of water bodies causes irreparable harm to fish stocks. In Canada, for example, due to frequent acid rain, more than 4 thousand lakes have been declared dead, and another 12 thousand are on the verge of death. The biological balance of 18 thousand lakes in Sweden has been disrupted. Fish have disappeared from half the lakes in southern Norway.
Due to the death of phytoplankton, sunlight penetrates to greater depths than usual. Therefore, all the lakes that died from acid rain are strikingly transparent and unusually blue.
Acid rain and forests. Acid rain causes enormous damage to forests, gardens, and parks. Leaves fall, young shoots become as fragile as glass and die. Trees become more susceptible to disease and pests, and up to 50% of their root system dies, mainly the small roots that feed the tree. In Germany, acid rain has already destroyed almost a third of all spruce trees. In forested areas such as Bavaria and Baden, up to half of the forest land was damaged. Acid rain causes damage not only to forests located on the plains; a number of damages have been recorded in the high-mountain forests of Switzerland, Austria, and Italy.
Acid rain and agricultural yieldstour. It has been established that the consequences of exposure to acid rain on agricultural crops are determined not only by their acidity and cationic composition, but also by duration and air temperature. In general, it has been established that the dependence of the growth and maturation of agricultural crops on the acidity of precipitation indicates the relationship between plant physiology, the development of microorganisms and a number of other factors. It is therefore obvious that a quantitative accounting of all components of acid rain that affect the yield and quality of products, as well as the complex processes of the functioning of soil biota for each specific region, is necessary.
Acid rain and materials. The impact of acid rain on a wide range of structural materials is becoming more and more obvious from year to year. Thus, accelerated corrosion of metals under the influence of acid precipitation, as noted by the American press, leads to the destruction of aircraft and bridges in the United States. As is known, the preservation of ancient monuments in Greece and Italy has become a serious problem. The main damaging ingredients are hydrogen cation, sulfur dioxide, nitrogen oxides, as well as ozone, formaldehyde and hydrogen peroxide.
The intensity of destruction of materials depends on: their porosity, since the higher the specific surface area, the greater its sorption capacity; from the design features, since in the presence of various recesses they are collectors of acid precipitation; on operating conditions: wind speed, temperature, air humidity, etc.
In practice, the greatest attention is paid to three groups of materials: metals - stainless steel and galvanized iron; from building materials - materials for external structures of buildings; from protective - paints, varnishes and polymers for surface coatings. When exposed to precipitation and gases, their damaging effect is determined by the intensity of catalytic reactions involving metals, as well as synergism (synergy is the ability of one substance to enhance the effect of another), with uniform corrosion most often observed.
According to the European Parliament, the economic damage from acid rain amounts to 4% of the gross national product. This must be taken into account when choosing a strategy to combat acid rain in the long term.
Specific measures to reduce sulfur emissions into the atmosphere are being implemented in two directions:
use of coal with low sulfur content at thermal power plants;
emissions cleaning.
Coals with a sulfur content of less than 1% are considered low-sulfur, and high-sulfur coals are those with a sulfur content of more than 3%. To reduce the likelihood of acid rain, high-sulfur coals are pre-treated. Coal usually contains pyrite and organic sulfur. Modern multi-stage methods of coal purification make it possible to extract up to 90% of all pyrite sulfur from it, i.e. up to 65% of its total quantity. To remove organic sulfur, chemical and microbiological treatment methods are currently being developed.
Similar methods must be applied to high-sulfur oil. World reserves of oil with low sulfur content (up to 1%) are small and amount to no more than 15%.
When burning fuel oil with a high sulfur content, special chemical additives are used to reduce the content of sulfur dioxide in emissions.
One of the simplest ways to reduce the amount of nitrogen oxides during fuel combustion is to carry out the process in conditions of a lack of oxygen, which is ensured by the speed of air supply to the combustion zone. Japan has developed a technology for “afterburning” primary combustion products. In this case, first the fuel (oil, gas) is burned in an optimal mode to form nitrogen oxides, and then the unreacted fuel is destroyed in the afterburning zone. At the same time, reactions leading to the reduction of oxides and their release are reduced by 80%.
The next direction in solving this problem is to abandon the practice of dispersing gaseous emissions. They should not be scattered, relying on the enormous scale of the atmosphere, but, on the contrary, captured and concentrated.
The most effective way to remove sulfur dioxide from emissions is based on its reaction with crushed lime. As a result of the reaction, 90% of the sulfur dioxide binds to the lime, forming gypsum, which can be used in construction. Thus, a thermal power plant with a capacity of 500 MW, equipped with an installation for purifying emissions, produces 600 thousand m 3 of gypsum per year.
A promising measure to reduce harmful impacts is to set limits on emissions. Thus, the US Environmental Protection Agency has set a limit on the total emission of sulfur dioxide in the country, providing for its annual reduction. This event had a certain positive effect.
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