What will acid rain cause? What is acid rain. Air pollution and acid precipitation
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 clean water 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.
Approximately two thirds acid rain 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, while some of them 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 create such global problems as global warming climate change and ozone depletion, their impact extends far beyond the country producing 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 into greater depth 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 diseases 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 acid precipitation, as the American press notes, leads to the destruction of planes and bridges in the United States. As is known, a serious problem has become the preservation ancient monuments in Greece and Italy. 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.
Low-sulfur coals are considered to have a sulfur content of less than 1%, 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.
Acid rain - all types of meteorological precipitation - rain, snow, hail, fog, sleet - in which there is a decrease in the pH of rainfall due to air pollution with acidic oxides, usually sulfur oxides and nitrogen oxides
Acid rain is one of the terms that industrialization brought to humanity.
First mentioned back in 1872, the concept became truly relevant only in the second half of the 20th century.
Certain level Any acidity has rainwater. But in the normal case, this indicator corresponds to a neutral pH level - 5.6-5.7 or slightly higher.
Prerequisites for increasing the acidity of atmospheric water arise when industrial enterprises emit large volumes of sulfur oxides and nitrogen oxides. The most typical sources of such pollution are vehicle exhaust gases, metallurgical production and thermal power plants (CHP). Unfortunately, modern level The development of purification technologies does not allow filtering out nitrogen and sulfur compounds that arise as a result of the combustion of coal, peat, and other types of raw materials that are used in industry.
Consequences of acid rain
1 Acid rain significantly increases the acidity of lakes, ponds, and reservoirs, as a result of which their natural flora and fauna gradually die out. As a result of changes in the ecosystem of water bodies, they become swamped, clogged, and have increased silt. In addition, as a result of such processes, water becomes unsuitable for human use. It increases the content of heavy metal salts and various toxic compounds, which under normal conditions are absorbed by the microflora of the reservoir.
2 Acid rain leads to forest degradation and plant extinction. They especially suffer coniferous trees, since the slow renewal of foliage does not give them the opportunity to independently eliminate the effects of acid rain. Young forests are also very susceptible to such precipitation, the quality of which is rapidly declining. With constant exposure to water with high acidity, trees die.
3 In the USA and Europe, acid rain is one of the common causes of poor harvests and the extinction of agricultural crops over vast areas. Moreover, the reason for such damage lies in both direct influence, which acid rain has on plants, and in violations of soil mineralization.
4 Acid rain causes irreparable damage to architectural monuments, buildings, and structures. The action of such precipitation causes accelerated corrosion of metals and failure of mechanisms.
5 Given the current acidity that acid rain has, in some cases it can cause direct harm to humans and animals. First of all, people in high-risk areas suffer from diseases of the upper respiratory tract. However, the day is not far off when the saturation of harmful substances in the atmosphere will reach a level at which sufficiently high concentrations of sulfuric and nitrate acid will fall out in the form of precipitation. In such a situation, the threat to human health will be significantly higher.
It is almost impossible to deal with precipitation itself. Falling over vast areas, acid rain causes significant damage, and there is no constructive solution to this problem.
Another thing is that in the case of acid rain, it is critically necessary to combat not the consequences, but the causes of this phenomenon. The search for alternative sources of energy production, environmentally friendly vehicles, new production technologies and technologies for purifying emissions into the atmosphere is an incomplete list of what humanity must attend to so that the consequences do not become catastrophic.
To solve the problem of acid rain, it is necessary to reduce emissions of sulfur dioxide and nitrogen oxide into the atmosphere. This can be achieved by several methods, including by reducing the energy received by humans from burning fossil fuels and increasing the number of power plants using alternative energy sources (energy sunlight, wind, tidal energy). Other opportunities to reduce emissions of pollutants into the atmosphere are:
- 1. Reduction of sulfur content in various types fuel. The most acceptable solution would be to use only those fuels that contain minimal amounts of sulfur compounds. However, there are very few such types of fuel. Only 20% of the world's oil reserves have a sulfur content of less than 0.5%. And in the future, unfortunately, the sulfur content in the fuel used will increase, since oil with low sulfur content is produced at an accelerated pace. The same is true with fossil coals. Removing sulfur from fuels has proven to be a very expensive process in financially Moreover, it is possible to remove no more than 50% of sulfur compounds from the fuel composition, which is an insufficient amount.
- 2. Application of tall pipes. This method does not reduce the impact on environment, but increases the efficiency of mixing pollutants in higher layers of the atmosphere, which leads to acid precipitation in more distant areas from the source of pollution. This method reduces the impact of pollution on local ecosystems, but increases the risk of acid rain in more remote regions.
- 3. Technological changes. The amount of nitrogen oxides NO that is formed during combustion depends on the combustion temperature. In the course of the experiments, it was possible to establish that what lower temperature combustion, the less nitrogen oxide is produced, and the amount of NO depends on the time the fuel is in the combustion zone with excess air.
Reductions in sulfur dioxide emissions can be obtained by cleaning the end gases from sulfur. The most common method is the wet process, where the resulting gases are bubbled through a limestone solution, resulting in the formation of sulfite and calcium sulfate. In this way it is possible to remove from the final gases greatest number sulfur.
4. Liming. To reduce acidification of lakes and soils, alkaline substances (CaCO 3) are added to them. This operation very often used in Scandinavian countries, where lime is sprayed from helicopters onto the soil or onto the catchment area. The Scandinavian countries suffer the most in terms of acid rain, since most Scandinavian lakes have granite or limestone-poor beds. Such lakes have a much lower ability to neutralize acids than lakes located in areas rich in limestone. But along with the advantages, liming also has its own number of disadvantages:
In flowing and rapidly mixing lake water, neutralization does not occur effectively;
Happening gross violation chemical and biological balance of water and soil;
Can't fix everything harmful effects acidification;
Liming cannot remove heavy metals. During a decrease in acidity, these metals turn into poorly soluble compounds and precipitate, but when a new portion of acid is added, they dissolve again, thus representing a constant potential danger to lakes.
It should be noted that a method has not yet been developed that, when burning fossil fuels, will reduce emissions of sulfur dioxide and nitrogen to a minimum, and in some cases completely prevent it.
History of the term
The term “acid rain” was first coined this year by the English researcher Robert Smith. The Victorian smog in Manchester caught his attention. And although scientists of that time rejected the theory of the existence of acid rain, today no one doubts that acid rain is one of the causes of the death of life in water bodies, forests, crops, and vegetation. In addition, acid rain destroys buildings and cultural monuments, pipelines, renders cars unusable, reduces soil fertility and can lead to toxic metals seeping into aquifers. The water of ordinary rain is also a slightly acidic solution. This occurs because natural atmospheric substances such as carbon dioxide (CO2) react with rainwater. This produces weak carbonic acid (CO2 + H2O -> H2CO3). . While ideally the pH of rainwater is 5.6-5.7, real life The pH value of rainwater in one area may be different from that of rainwater in another area. This, first of all, depends on the composition of gases contained in the atmosphere of a particular area, such as sulfur oxide and nitrogen oxides. In 2009, the Swedish scientist Svante Arrhenius coined two terms - acid and base. He called acids substances that, when dissolved in water, form free positively charged hydrogen ions (H+). He called bases substances that, when dissolved in water, form free negatively charged hydroxide ions (OH-). The term pH is used as an indicator of the acidity of water. The term pH means, translated from English, an indicator of the degree of concentration of hydrogen ions.
Chemical reactions
It should be noted that even normal rainwater has a slightly acidic (pH about 6) reaction due to the presence of carbon dioxide in the air. Acid rain is formed by a reaction between water and pollutants such as sulfur oxide (SO2) and various nitrogen oxides (NOx). These substances are emitted into the atmosphere by road transport, as a result of the activities of metallurgical enterprises and power plants. Sulfur compounds (sulfides, native sulfur and others) are contained in coals and ores (especially a lot of sulfides in brown coals), when burned or roasted, volatile compounds are formed - sulfur oxide (IV) - SO 2 - sulfur dioxide, sulfur oxide (VI) - SO 3 - sulfuric anhydride, hydrogen sulfide - H 2 S (in small quantities, with insufficient firing or incomplete combustion, at low temperature). Various nitrogen compounds are contained in coals, and especially in peat (since nitrogen, like sulfur, is part of biological structures, from which these minerals were formed). When such fossils are burned, nitrogen oxides (acid oxides, anhydrides) are formed - for example, nitrogen oxide (IV) NO 2. Reacting with atmospheric water (often under the influence solar radiation, so-called “photochemical reactions”), they are converted into solutions of acids - sulfuric, sulfurous, nitrous and nitric. Then, along with snow or rain, they fall to the ground.
Environmental and economic consequences
The consequences of acid rain are observed in the USA, Germany, the Czech Republic, Slovakia, the Netherlands, Switzerland, Australia, the republics of the former Yugoslavia and many more countries globe. Acid rain has a negative impact on bodies of water - lakes, rivers, bays, ponds - increasing their acidity to such a level that flora and fauna die in them. There are three stages of the impact of acid rain on water bodies. The first stage is the initial stage. With an increase in water acidity (pH values less than 7), aquatic plants begin to die, depriving other animals of the reservoir of food, the amount of oxygen in the water decreases, and algae (brown-green) begin to rapidly develop. The first stage of eutrophication (swamping) of a reservoir. At pH6 acidity, freshwater shrimp die. The second stage - acidity rises to pH5.5, bottom bacteria die, which decompose organic matter and leaves, and organic waste begins to accumulate at the bottom. Then plankton, the tiny animal that forms the basis, dies food chain reservoir and feeds on substances formed during decomposition by bacteria organic matter. The third stage - acidity reaches pH 4.5, all fish, most frogs and insects die. The first and second stages are reversible when the impact of acid rain on the reservoir ceases. As organic matter accumulates at the bottom of water bodies, toxic metals begin to leach out. Increased acidity of water contributes to higher solubility of such hazardous metals like aluminum, cadmium, and lead from sediments and soils. These toxic metals pose a risk to human health. People, drinking water with high levels of lead or who eat fish containing high levels of mercury may acquire serious illnesses. Acid rain not only harms aquatic flora and fauna. It also destroys vegetation on land. Scientists believe that although the mechanism has not yet been fully understood, “a complex mixture of pollutants, including acid precipitation, ozone, and heavy metals, collectively lead to forest degradation. Economic losses from acid rain in the United States, according to one study, are estimated at east coast 13 million dollars and by the end of the century losses will reach 1.750 billion dollars from forest loss; $8.300 billion in crop losses (in the Ohio River Basin alone) and $40 million in medical expenses in Minnesota alone. The only way To change the situation for the better, according to many experts, is to reduce the amount of harmful emissions into the atmosphere.
Literature
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See what “Acid rain” is in other dictionaries:
- (acid rain) precipitation(including snow), acidified (pH below 5.6) due to the increased content of industrial emissions in the air, mainly SO2, NO2, HCl, etc. As a result of acid rain entering the surface layer of soil and... ... Big Encyclopedic Dictionary
- (acid rain), characterized by a high 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 … Modern encyclopedia
Rain caused by atmospheric pollution with sulfur dioxide (SO2). They have a biocidal effect, in particular, the death of fish (for example, in the waters of Scandinavia due to the transfer of lawn emissions in the industrial cities of England). Ecological Dictionary. Alma Ata:... ... Ecological dictionary
acid rain- – rains with pH 5.6. General chemistry: textbook / A. V. Zholnin ... Chemical terms
- (acid rain), precipitation (including snow), acidified (pH below 5.6) due to the increased content of industrial emissions in the air, mainly SO2, NO2, HCl, etc. As a result of acid rain entering the surface layer soil... Encyclopedic Dictionary
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... ... Geographical encyclopedia
Acid rain- (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... ... Peoples and cultures
- (acid rain), atm. precipitation (including snow), acidified (pH below 5.6) due to increased industrial air content emissions, ch. arr. SO2, NO2, HCl, etc. As a result of the entry of acid into the surface layer of soil and water bodies, acidification develops, which... ... Natural science. Encyclopedic Dictionary
Acid rain- are caused by the presence in the atmosphere of sulfur and nitrogen dioxides, which appear due to the oxidation of sulfur and nitrogen during the combustion of fossil fuels. Further oxidation occurs in clouds, reactions in which are catalyzed by ozone,... ... The beginnings of modern natural science
Ecology
Acid rain, which is described as sulfuric and nitric acids deposited in the atmosphere, is a serious environmental problem. Although often associated with rainfall, the term also refers to acidic solids. These acids are the result of sulfur dioxide and nitrogen oxide, which react with moisture and other substances in the atmosphere. While there are natural sources of these chemicals, experts are increasingly focusing on man-made sources such as coal-fired power plants.
What are the dangers of acid rain? Firstly, acid rain contributes to the acidification of soil, rivers and lakes, which exceeds the permissible limits for plants and animals, and it also destroys man-made structures. What other effects does acid rain have?
Oxidation of waters
Water resists rapid changes in pH, a measure of the acidity of a substance, which when low indicates more acidity. However, even this resistance can be overcome by constant and prolonged exposure to acid rain. Ecosystems of rivers and lakes are especially susceptible to such changes. For example, mayflies die at an acidity of pH 5.5, while trout and perch can survive in more acidic water. However, as populations of mayflies and other insects decline, those same trout will face insufficient food to support their populations. Also, at a pH of 5, many fish cannot hatch and raise young fish from eggs, which undermines the health of the fish population.
Forests
Direct contact with acid rain weakens trees and destroys their leaves. This is especially true in forests at high altitudes, where trees are often submerged in an acid cloud. Acid rain can also damage trees in more subtle ways, reducing nutrient levels and increasing levels of toxic compounds in the soil.
Cars
Many people work hard to improve the appearance of their car, but acid rain can literally destroy the protective coating of your vehicle. To combat these effects of acid rain, many car manufacturers have begun coating their cars with special acid-resistant paints.
Buildings
Limestone and marble structures are especially susceptible to acid rain. All this occurs due to the content of the mineral calcite in these materials, which is easily dissolved. Damage is easily visible on old stone buildings and monuments where the carvings have eroded over time. Not all stones are affected by this. Granite and sandstone have a chemical composition that does not react with acid rain, although some types of sandstone contain carbonate that the acid reacts with.
Human health
Acid rain looks like regular rain, without having any distinctive taste or causing any unusual sensations. The harm caused by acid rain to humans is not direct. Walking in acid rain, or even swimming in a lake exposed to acid rain, is no more dangerous than swimming in clear water. However, the pollutants that cause acid rain do cause harm to human health. Sulfur dioxide and nitrogen oxide react with the atmosphere to form pure sulfate and nitrogen particles, which are carried long distances by wind and inhaled into people's lungs. Small particles can also find their way into your home. Many studies have found a link between increased levels of fine particles and the risk of disease and premature death from heart disorders and respiratory diseases such as asthma and bronchitis.
The only way to combat acid rain is to limit emissions of the pollutants that cause it. And even if the best-case scenario were to stop acid rain, it would take many years for the harmful effects of acid rain to completely disappear.