Robert Smith scientist acid rain. How to deal with acid rain: basic methods

The term “acid rain” was introduced by the English chemist R.E. Smith more than 100 years ago.

In 1911, cases of fish death as a result of acidification of natural water were recorded in Norway. However, it was only in the late 60s, when similar cases in Sweden, Canada, and the United States attracted public attention, that the suspicion arose that the cause was rain with a high content of sulfuric acid.

Acid rain is precipitation (rain, snow) with a pH less than 5.6 (high acidity).

Acid rain is formed by industrial emissions of sulfur dioxide and nitrogen oxides into the atmosphere, which, when combined with atmospheric moisture, form sulfuric and nitric acids. As a result, rain and snow become acidified (pH number below 5.6). In Bavaria (Germany) in August 1981, rain fell with an acidity pH = 3.5. Maximum recorded precipitation acidity in Western Europe- pH = 2.3.

The total global anthropogenic emissions of sulfur and nitrogen oxides annually amount to more than 255 million tons (1994). Acid-forming gases remain in the atmosphere for a long time and can travel over distances of hundreds and even thousands of kilometers. Thus, a significant portion of UK emissions ends up in Nordic countries(Sweden, Norway, etc.), i.e. with cross-border transport, and harms their economies.

Everyone knows what water is. There is a huge amount of it on Earth - one and a half billion cubic kilometers.

If you imagine Leningrad region the bottom of a giant glass and try to contain all the water of the Earth in it, then its height should be greater than the distance from the Earth to the Moon. It would seem that there is so much water that there should always be enough of it. But the trouble is that all oceans have salty water. We, and almost all living things, need fresh water. But there isn't much of it. That's why we desalinate water.

IN fresh water rivers and lakes contain a lot of soluble substances, including poisonous ones, it may contain pathogenic microbes, so it cannot be used, much less drunk, without additional purification. When it's raining, drops of water (or snowflakes when it snows) are captured from the air harmful impurities that got into it from the pipes of some factory.

As a result, harmful, so-called acid rain falls in some places on Earth. Neither plants nor animals like it.

The beneficial drops of rain have always brought joy to people, but now in many areas of the planet, rain has turned into a serious danger.

Acid precipitation (rain, fog, snow) is precipitation whose acidity is higher than normal. A measure of acidity is the pH value (hydrogen value). The pH scale goes from 02 (extremely acidic), through 7 (neutral) to 14 (alkaline), with the neutral point ( clean water) has pH=7. Rainwater in clean air has a pH of 5.6. The lower the pH value, the higher the acidity. If the acidity of the water is below 5.5, then the precipitation is considered acidic. In vast areas industrially developed countries Around the world there is precipitation, the acidity of which exceeds normal by 10 - 1000 times (pH = 5-2.5).

Chemical analysis acid precipitation indicates the presence of sulfuric (H 2 SO 4) and nitric (HNO 3) acids. The presence of sulfur and nitrogen in these formulas indicates that the problem is associated with the release of these elements into the atmosphere. When fuel is burned, sulfur dioxide enters the air, and atmospheric nitrogen also reacts with atmospheric oxygen and nitrogen oxides are formed.

These gaseous products (sulfur dioxide and nitrogen oxide) react with atmospheric water to form acids (nitric and sulfuric).

IN aquatic ecosystems acid precipitation cause the death of fish and other aquatic life. Acidification of river and lake water also seriously affects land animals, since many animals and birds are part of food chains that begin in aquatic ecosystems.

Along with the death of lakes, forest degradation also becomes apparent. Acids destroy the protective waxy coating of leaves, making plants more vulnerable to insects, fungi and other pathogens. During drought, more moisture evaporates through damaged leaves.

The leaching of nutrients from the soil and the release of toxic elements contribute to the slowdown of tree growth and death. One can imagine what happens to wild animal species when forests die.

If destroyed forest ecosystem, then soil erosion begins, clogging of water bodies, flooding and deterioration of water supplies become catastrophic.

As a result of acidification in the soil, dissolution occurs nutrients, vital for plants; These substances are carried by rain into groundwater. At the same time, heavy metals are leached from the soil, which are then absorbed by plants, causing serious damage to them. Using such plants for food, a person also receives an increased dose of heavy metals with them.

When the soil fauna degrades, yields decrease, the quality of agricultural products deteriorates, and this, as we know, entails a deterioration in public health.

Under the influence of acids from rocks and minerals, aluminum is released, as well as mercury and lead. which then end up in surface and groundwater. Aluminum can cause Alzheimer's disease, a type of premature aging. Heavy metals found in natural waters negatively affect the kidneys, liver, central nervous system, causing various cancers. Genetic consequences heavy metal poisoning can take 20 years or more to appear not only in those who consume dirty water, but also among their descendants.

Acid rain corrodes metals, paints, synthetic compounds, and destroys architectural monuments.

Acid rain is most common in industrialized countries with highly developed energy systems. Over the course of a year, thermal power plants in Russia emit about 18 million tons of sulfur dioxide into the atmosphere, and in addition, thanks to western air transport, sulfur compounds come from Ukraine and Western Europe.

To combat acid rain, efforts must be directed toward reducing emissions of acid-forming substances from coal-fired power plants. And for this you need:

using low-sulfur coal or removing sulfur from it

installation of filters for purification of gaseous products

use of alternative energy sources

Most people remain indifferent to the problem acid rain. Are you going to wait indifferently for the destruction of the biosphere or are you going to take action?

Removal, processing and disposal of waste from hazard classes 1 to 5

We work with all regions of Russia. Valid license. A complete set of closing documents. Individual approach to the client and flexible pricing policy.

Using this form, you can submit a request for services, request a commercial offer, or receive a free consultation from our specialists.

Send

Acid rain is a mixture of materials, both wet and dry, that fall to the earth from the atmosphere. They contain increased level 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 cars 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 has a slightly acidic environment 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 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 which 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 number Acid precipitation occurs 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, in lately Acid precipitation is 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 various 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 the acid reaches the ground, it has negative impact for a large number of species of animals, plants and aquatic organisms. Water enters rivers and canals, which mix with sea ​​water, thereby influencing marine environment habitat.

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 acidity level water resources rises 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 they 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 dedicated 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:

1. The main natural cause of acid rain is volcanic emissions. Volcanoes emit acid-forming gases that create abnormal acidity. Against this backdrop, a record amount of precipitation falls. The earth suffers from phenomena such as fog and snow. Vegetation and the health of residents in the vicinity of volcanic formations suffer.
2. Rotting vegetation forest fires And biological processes in the environment and generate acid rain, forming gases.
3. 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 emissions gaseous substances, which leads to acid rain.

Cars and factories also release large amounts of gaseous emissions into the air. The worst thing is that this process is repeated daily, especially in industrialized areas of the city with a large number car movement. 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 to 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. Impact on aquatic environment very large. 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.

Smog

Air pollution

As a result of pollution environment many local and global environmental problems arise, which are characteristic feature modern environmental crisis. The most famous of them are related to air pollution. The following is information about some of these phenomena.

Ambient air pollution- this is any change in its state and properties that has negative impact on human and animal health, the state of plants and ecosystems. Atmospheric pollution can be natural (natural) or anthropogenic (man-made).

Natural pollution air pollution is caused by volcanic activity, weathering of rocks, wind erosion, smoke from forest and steppe fires.

Anthropogenic pollution associated with the release of various pollutants during human activities. In its scale it significantly exceeds natural pollution.

Distinguish local, regional and global pollution atmosphere. An example of local pollution is the area of ​​Krasnoyarsk, adjacent to KRAZ; regional - the Putorana plateau in the vicinity of Norilsk; global - increased CO 2 content in the entire modern atmosphere of the globe.

The main pollutants (pollutants) are sulfur dioxide (SO 2), carbon oxides (CO) and particulate matter. They account for about 98% of the total volume of harmful substances. In addition to the main pollutants, about 70 other types of harmful substances are observed in the atmosphere of cities and large towns, among which the most common are formaldehyde, hydrogen fluoride, ammonia, phenol, benzene, carbon disulfide, etc. However, in many cities the concentration of the main pollutants is sulfur dioxide and carbon monoxide – most often exceeds permissible levels.

Main sources air pollution are thermal and nuclear power plants, boiler plants, ferrous metallurgy enterprises, chemical production, vehicle emissions, gas and oil refining, waste incineration.

The following main types of air pollution are distinguished: smog, acid precipitation, accumulation greenhouse gases and disruption of the ozone shield.

Smog– (in a broad sense) any air pollution visible to the naked eye.

The very first officially recorded case of air pollution that had serious consequences was smog in the city of Donora (USA) in 1948. Within 36 hours, two dozen deaths were registered, hundreds of residents felt very ill. Four years later, in December 1952, an even more tragic incident occurred in London. More than 4,000 people died in five days due to air pollution. Although in subsequent years severe smog was observed in London and other cities more than once, such catastrophic consequences, fortunately, there were no more.

Formation conditions: dust and gas air pollution combined with unfavorable weather conditions (high humidity air, increased solar activity), resulting in a synergistic (mutually reinforcing) effect. An additional condition for increased smog is calm weather and temperature inversion. The latter manifests itself in the blocking of cold air above the ground by a layer of warm air above. This happens when cold air “leaks” (wedges) under warm air. As a result upward movement air is blocked and pollutants are not carried upward, but accumulate above the Earth. The phenomenon of temperature inversion can be enhanced by relief features. Thus, the mountains surrounding the contaminated area prevent the horizontal outflow of pollutants.

There are three types of smog:

· Wet smog (London type) - a combination of gaseous pollutants (mainly SO 2), dust particles and fog droplets. Concentrations of sulfur oxides, dust and carbon monoxide reach levels dangerous to humans. So, in 1952 in London, more than 4,000 people died from the humidity of smog.

· Icy smog (Alaskan type) - a combination of dust and gas pollution and frozen fog drops.

· Photochemical smog (Los Angeles type) - secondary air pollution due to the decomposition and chemical interaction of pollutants, primarily nitrogen oxides and volatile hydrocarbons, under the influence of sun rays. The consequence of secondary atmospheric pollution during photochemical smog is the formation of photochemical oxidizers (aggressive and harmful compounds O 3 (ozone), CO (carbon monoxide), peroxyl cyl nitrates (PAN), etc. In Tokyo alone in 1970, this type of smog caused the poisoning of 10 thousand people , and in 1971 – 28 thousand.

Conditions for the formation of photochemical smog. Fuel combustion in a car engine occurs when high temperature, the interaction between oxygen and nitrogen, which are part of the atmospheric air, begins. Atomic oxygen formed during the dissociation of oxygen molecules is capable of splitting a molecule of relatively inert nitrogen, initiating a chain reaction:

O 2 + light quantum ® O* + O* (oxygen radicals)

O* + N 2 ® NO + N*

N* + O 2 ® NO + O*

As a result, nitrogen monoxide appears in the exhaust gases, which, once released into the atmosphere, is oxidized by atmospheric oxygen, turning into nitrogen dioxide. Brown nitrogen dioxide is photochemically active. Absorbing light, it dissociates:

Thus, a reactive oxygen atom appears in the air, which can react to form ozone:

O* + O 2 ® O 3 .

The presence of ozone is the most characteristic feature photochemical smog. It is not formed during fuel combustion, but is a secondary pollutant. Possessing strong oxidizing properties, ozone has a harmful effect on human health and destroys many materials, primarily rubber.

TO negative consequences smog applies:

§ deterioration of people’s condition (headaches, suffocation, nausea, allergic phenomena on the skin, eyes, mucous membranes of the upper respiratory tract); may increase mortality;

§ smog leads to drying out of vegetation and loss of crop yields;

§ causes premature wear of buildings, metal structures, rubber products, etc. For example, Los Angeles smog is more damaging to rubber, while London smog is more damaging to iron and concrete.

Nowadays, environmental problems of motor transport in large Russian cities have become a serious problem. Thus, automobile emissions in Moscow and St. Petersburg amount to hundreds of thousands of tons per year. Motor transport has confidently taken first place among all other sources of air pollution. Therefore, in Moscow, St. Petersburg and others major cities smog becomes a frequent visitor, especially in calm weather.

For smog prevention is necessary :

§ improve car engines;

§ effectively purify exhaust gases;

§ The amount of carbon monoxide produced in car engines can be reduced by burning it into less dangerous carbon dioxide. Increasing the proportion of air in the combustible mixture helps to reduce the emission of not only CO, but also unburned hydrocarbons. The most effective are catalytic converters, in which carbon monoxide and unburned hydrocarbons are oxidized to carbon dioxide and water, and nitrogen oxides are reduced to molecular nitrogen. Unfortunately, catalytic afterburners cannot be used when refueling a car with leaded gasoline. Such gasoline contains lead compounds that irreversibly poison the catalyst. Alas, leaded gasoline is still widely used in our country;

§ to reduce sulfur dioxide emissions, sulfur compounds are first removed from oil, and the exhaust flue gases are further purified. The release of sulfur compounds into the atmosphere can also be reduced by burning solid fuel in a fluidized bed. Particulate matter emissions from thermal power plants are reduced by using electrostatic precipitators or vacuum air filters.

Acid precipitation– this is any precipitation (rain, fog, snow), the acidity of which is lower than normal due to its acidification by air impurities. Acid precipitation also includes the loss of dry acidic particles from the atmosphere (otherwise known as acid deposits).

The term "acid rain" was coined in 1872. English engineer Robert Smith in his monograph Air and Rain: The Beginnings of Chemical Climatology. In the absence of pollutants in the air, the reaction of rainwater is slightly acidic (pH = 5.6), since it easily dissolves carbon dioxide from the air to form weak carbonic acid. Therefore, precipitation with a pH value of 5.5 should be more accurately called acidic.

Chemical analysis of acid precipitation shows the presence of sulfuric (H 2 SO 4) and nitric (HNO 3) acids. The presence of sulfur and nitrogen in these formulas indicates that the problem is associated with the release of these elements into the atmosphere. When fuel is burned, sulfur dioxide is released into the air, and atmospheric nitrogen also reacts with atmospheric oxygen to form nitrogen oxides. Therefore, the conditions for the formation of acid precipitation are the massive entry into the atmosphere of sulfur dioxide (SO 2) and nitrogen oxides (NO 2, etc.), which, due to their dissolution in water, acidify the precipitation:

SO 3 + H 2 O ® H 2 SO 4,

NO 2 + H 2 O ® HNO 3 .

The acidity of sediments is usually due to the presence of sulfuric acid 2/3 and nitric acid 1/3.

Figure 2. Mechanism of formation of acid precipitation

The acidity of precipitation depends both on the amount of acids (the level of atmospheric pollution with sulfur and nitrogen oxides) and on the amount of water entering the earth in the form of precipitation. The pH decreases (which means the acidity increases) of precipitation in the following sequence: heavy rains ® drizzles ® fogs. Acid dew, which is formed from acid deposits (dry acidic precipitation) on the surface of plants and other objects when it falls, can have significant acidity. small quantity dripping water (dew).

Acid precipitation illustrates the threshold effect. Most soils, lakes and rivers contain alkaline chemicals that can react with some acids, neutralizing them. However, regular, long-term exposure to acids depletes most of these acidifying agents. Then, as if suddenly, the mass death of trees and fish in lakes and rivers begins. When this happens, it is too late to take any measures to prevent serious damage. The delay is 10 - 20 years.

Sources releases of sulfur and nitrogen oxides into the atmosphere: thermal power plants (working on low-grade coal and fuel oil); industrial boiler houses; exhaust gases from motor vehicles, etc. The resulting weak solutions of sulfuric and nitric acid in the atmosphere can fall out as precipitation, sometimes several days later, hundreds of kilometers from the source of emission (Figure 2).

In general, the acidity of precipitation, especially in places where industrial enterprises are concentrated, can be 10-1000 times higher than normal.

Dynamics. Acid rain was first noted in Western Europe, particularly in Scandinavia, and North America in the 1950s Now this problem exists throughout the industrial world, and has become special meaning due to increased technogenic emissions of sulfur and nitrogen oxides.

On average, the acidity of precipitation, which falls mainly in the form of rain in Western Europe and North America over an area of ​​almost 10 million km 2, is 5-4.5, and fogs here often have a pH of 3-2.5.

In Russia the most high levels fallout of oxidized sulfur and nitrogen oxides (up to 750 kg/km2 per year) over large areas (several thousand km2) are observed in densely populated and industrial regions of the country - in the Northwestern, Central, Central Black Earth, Ural and other regions ; in local areas (up to 1 thousand km2 in area) - in the immediate vicinity of metallurgical enterprises, large state district power plants, as well as large cities and industrial centers (Moscow, St. Petersburg, Omsk, Norilsk, Krasnoyarsk, Irkutsk, etc.), saturated power plants and motor transport. The minimum pH values ​​of precipitation in these places reach 3.1-3.4. The Republic of Sakha (Yakutia) is recognized as the most favorable region in this regard.

A specific feature of acid rain is its transboundary nature, due to the transfer of acid-forming emissions by air currents over long distances - hundreds and even thousands of kilometers. This is greatly facilitated by the once adopted “high chimney policy” as effective remedy against ground air pollution.

Almost all countries are simultaneously “exporters” of their own and “importers” of others’ emissions. The greatest contribution to the transboundary acidification of the Russian natural environment with sulfur compounds is made by Ukraine, Poland, and Germany.

About 75% of the acid deposition that falls in Canada is blown from the United States, and only 15% of the acid deposition that falls in the northeastern states comes from emissions within Canada. This large positive balance of acid deposition transport between the United States and Canada led to strained relations between the two countries.

Canadian scientists and officials and many US scientists have criticized the US government for not moving quickly enough to reduce harmful emissions from industrial plants and power plants by at least 50%. The Ontario Ministry of Environment estimates that acid deposition threatens 48,000 Canadian lakes and their $1.1 billion-a-year sport fishing and $10-billion-a-year tourism industries. Canadians are also concerned that acid deposition is harming forestry and related industries, which employ one in 10 people in the country and generate $14 billion a year.

The consequences of acid precipitation are limited to a negative impact on ecosystem components:

1. Acid precipitation leads to forest degradation due to direct burns of plant tissues, leaching of nutrients from soils, and decreased plant resistance to pests and diseases. The leaching of aluminum and heavy metals from the soil by incoming acids, and their further entry into plants or water bodies, causes poisoning of organisms. Forests are drying out, and dry tops are developing over large areas. Acid increases the mobility of aluminum in soils, which is toxic to small roots, and this leads to oppression of foliage and needles, and brittleness of branches. Coniferous trees are especially affected because the needles are replaced less frequently than the leaves, and therefore accumulate more harmful substances over the same period. Coniferous trees They turn yellow, their crowns thin out, and small roots are damaged. But also deciduous trees The color of the leaves changes, the foliage falls off prematurely, part of the crown dies, and the bark is damaged. Natural regeneration of conifers and deciduous forests doesn't happen. In the mid-70s, it began to be noticed that Norway spruce thickets began to turn yellow and crumble; 50 million hectares of forest in 25 European countries were suffering from a complex mixture of pollutants, including acid rain. Examples:

§ In Holland and Great Britain, by 1986, about a third of trees were “completely or moderately naked.” In Germany the same thing happened with 20%, in Czechoslovakia and Switzerland with about 16% of trees.

§ In Germany, 30%, and in some places 50% of forests were damaged. And all this happens far from cities and industrial centers. It turned out that the cause of all these troubles is acid rain.

§ In addition, atmospheric pollution from thermal power plants and thermal power plants has led, as scientists believe, to a new phenomenon of damage to some types of soft tree species, as well as to a rapid and simultaneous drop in the growth rate of at least six species of coniferous trees.

3. Scandinavia felt a particularly negative impact from “acid rain”. In the 70s in rivers and lakes fish began to disappear in the Scandinavian countries, the snow in the mountains turned gray, leaves from the trees covered the ground ahead of time. Very soon the same phenomena were noticed in the USA, Canada, and Western Europe. The pH value varies in different bodies of water, but in undisturbed natural environment the range of these changes is strictly limited. Natural waters and soils have buffering capabilities, they are able to neutralize certain part acid and preserve the environment. However, it is obvious that nature’s buffering capacity is not unlimited. The intensity of the impact depends on the buffer capacity of the ecosystem. However, the capabilities of the buffer are limited; with the continuous entry of acid precipitation into the ecosystem, it is chemically consumed and there comes a point at which even a slight further arrival acid leads to a decrease in pH in the ecosystem biotope. As pH decreases in aquatic ecosystems, reproductive capacity decreases and death (primarily of more primitive) organisms is noted; Long-term food chains are disrupted not only in water, but also in near-aquatic terrestrial ecosystems. Recorded:

§ Reduced ability to reproduce salmon and trout at pH< 5,5.

§ Death and decreased productivity of many species of phytoplankton when pH<6 – 8.

§ Disruption of the nitrogen cycle in lakes, when the pH value ranges from 5.4 to 5.7.

§ Damage to tree roots and death of many fish species due to the release of aluminum, lead, mercury and cadmium ions from soils and bottom sediments.

4. Canadian ecologists were able to establish that the population of coral reef inhabitants Caribbean Sea fish population has decreased by 32-72% over the past 10-15 years. This is reported by Science NOW. Ecologists name several possible reasons for the decline in coral numbers. Among them are an increase in water acidity due to rising levels of CO 2 in the atmosphere and rising ocean temperatures.

5. Acid rain not only kills wildlife, but also destroy architectural monuments . Durable, hard marble, a mixture of calcium oxides (CaO and CO 2), reacts with a solution of sulfuric acid and turns into gypsum (CaSO 4). Temperature changes, rain and wind destroy this soft material. Historical monuments of Greece and Rome, having stood for millennia, have been destroyed right before our eyes in recent years. The same fate threatens the Taj Mahal, a masterpiece of Indian architecture of the Mughal period, and in London the Tower and Westminster Abbey. At St. Paul's Cathedral in Rome, a layer of Portland limestone has been eroded by an inch. In Holland, the statues at St. John's Cathedral are melting like candy. The royal palace on Dam Square in Amsterdam is corroded by black deposits. More than 100 thousand valuable stained glass windows decorating the cathedrals in Tabernacle, Conterbury, Cologne, Erfurt, Prague, Bern, and other European cities may be completely lost in the next 15 - 20 years.

6. A study of the health histories of large numbers of urban residents clearly shows that urban areas with the highest levels of air pollution have the highest number of respiratory diseases and the lowest average life expectancy. Effect on people and products:

· allergic reactions of the skin and mucous membranes in humans;

· premature wear due to accelerated corrosion of buildings, structures, architectural monuments (made of marble);

· the productivity of agricultural land is sharply reduced.

Measures to reduce the destructive effects of acid precipitation. It is necessary to save nature from acidification. To do this, it will be necessary to sharply reduce emissions of sulfur and nitrogen oxides into the atmosphere, but primarily sulfur dioxide, since it is sulfuric acid and its salts that account for 70–80% of the acidity of rain that falls at large distances from the site of industrial emissions.

Water bodies damaged by acid rain can be given new life by small amounts of phosphate fertilizers; they help plankton absorb nitrates, which leads to a decrease in water acidity. Phosphate is less expensive to use than lime, and phosphate also has less impact on water chemistry.

One of the measures to control acid deposition is monitoring. Observations of the chemical composition and acidity of precipitation in Russia are carried out by 131 stations that take total samples for chemical analysis, and 108 points at which only the pH value is promptly measured.

The snow cover pollution control system in Russia is carried out at 625 points, surveying an area of ​​15 million km 2. Samples are taken for the presence of sulfate ions, ammonium nitrate, heavy metals, and the pH value is determined.

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 found in coals, and especially in peat (since nitrogen, like sulfur, is part of the 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 of solar radiation, so-called “photochemical reactions”), they turn into acid solutions - sulfuric, sulphurous, nitrogenous and nitrogenous. 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 other countries around the 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 debris 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 water promotes higher solubility of hazardous metals such as 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 with high levels of mercury can become seriously ill. 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

Wikimedia Foundation. 2010.

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