Causes of acid rain. Acid rain: causes, consequences, methods of struggle

Causes of acid rain

Main reason for dropout acid rain — the presence in the atmosphere due to industrial emissions of sulfur and nitrogen oxides, hydrogen chloride and other acid-forming compounds. As a result, rain and snow are acidified. Acid rain formation and its impact on environment shown in fig. 1 and 2.

The presence in the air of noticeable amounts, for example, ammonia or calcium ions, leads to the precipitation of not acidic, but alkaline precipitation. However, they are also called acidic, since they change their acidity when they enter the soil or into a reservoir.

The maximum recorded acidity of precipitation in Western Europe- with pH = 2.3, in China - with pH = 2.25. Author study guide On the experimental base of the Ecological Center of the Russian Academy of Sciences in the Moscow region in 1990, rain was recorded with pH = 2.15.

Acidification natural environment negatively affects the condition. In this case, not only nutrients are leached from the soil, but also toxic metals, such as lead, aluminum, etc.

In acidified water, the solubility of aluminum increases. In lakes, this leads to disease and death of fish, to a slowdown in the development of phytoplankton and algae. Acid rain destroys facing materials (marble, limestone, etc.), significantly reduces the service life of reinforced concrete structures.

Thus, environmental oxidation- one of the most important environmental issues that needs to be addressed in the near future.

Rice. 1. Formation of acid rain and its impact on the environment

Rice. 2. Approximate acidity of rainwater and some substances in pH units

The acid rain problem

The development of industry, transport, the development of new energy sources lead to the fact that the amount of industrial emissions is constantly increasing. This is mainly due to the use of fossil fuels in thermal power plants, industrial enterprises, in car engines and in residential heating systems.

As a result of the combustion of fossil fuels, compounds of nitrogen, sulfur, chlorine, and other elements enter the Earth's atmosphere. Among them, oxides of sulfur - S0 2 and nitrogen - NO x (N 2 0, N0 2) predominate. Combining with water particles, sulfur and nitrogen oxides form sulfuric (H 2 SO 4) and nitric (HNO 3) acids of various concentrations.

In 1883, the Swedish scientist S. Arrhenius coined two terms - "acid" and "base". He called acids substances that, when dissolved in water, form free positively charged hydrogen ions (H +), and bases - substances that, when dissolved in water, form free negatively charged hydroxide ions (OH -).

Aqueous solutions can have a pH (an indicator of the acidity of water, or an indicator of the degree of concentration of hydrogen ions) from 0 to 14. Neutral solutions have a pH of 7.0, an acidic environment is characterized by pH values \u200b\u200bless than 7.0, alkaline - more than 7.0 (Fig. 3 ).

In an environment with a pH of 6.0, fish species such as salmon, trout, roach and freshwater shrimp. At pH 5.5, pubic bacteria die, which decompose organic matter both leaves and organic debris begin to accumulate on the bottom. Then plankton dies - tiny unicellular algae and protozoan invertebrates that form the basis the food chain reservoir. When the acidity reaches pH 4.5, all fish die, most frogs and insects, only a few species of freshwater invertebrates survive.

Rice. 3. Acidity scale (pH)

It has been established that the share of technogenic emissions associated with the combustion of fossil coal accounts for about 60-70% of their total amount, the share of petroleum products - 20-30%, the rest production processes- 10 %. 40% of NO x emissions are vehicle exhaust gases.

The effects of acid rain

Characterized by a strongly acidic reaction (usually pH<5,6), получили название кислотных (кислых) дождей. Впервые этот термин был введен британским химиком Р.Э. Смитом в 1872 г. Занимаясь вопросами загрязнения г. Манчестера, Смит доказал, что дым и пары содержат вещества, вызывающие серьезные изменения в химическом составе дождя, и что эти изменения можно заметить не только вблизи источника их выделения, но и на большом расстоянии от него. Он также обнаружил некоторые вредные effects of acid rain: discoloration of fabrics, corrosion of metal surfaces, destruction of building materials and death of vegetation.

Experts argue that the term "acid rain" is not accurate enough. For this type of pollutant, the term "acid precipitation" is better suited. Indeed, pollutants can fall not only in the form of rain, but also in the form of snow, clouds, fog (“wet precipitation”), gas and dust (“dry precipitation”) during the dry period.

Although the alarm sounded more than a century ago, industrialized nations have long ignored the dangers of acid rain. But in the 60s. 20th century Ecologists have reported a decrease in fish stocks and even its complete disappearance in some lakes in Scandinavia. In 1972, the problem of acid rain was first raised by environmental scientists in Sweden at the UN Conference on the Environment. Since that time, the danger of global acidification of the environment has become one of the most acute problems that have befallen humanity.

As of 1985 in Sweden, fisheries in 2,500 lakes have been severely affected by acid rain. In 1750, out of 5,000 lakes in southern Norway, fish completely disappeared. A study of the reservoirs of Bavaria (Germany) showed that in recent years there has been a sharp decrease in the number, and in some cases, the complete disappearance of fish. When studying 17 lakes in the autumn, it was found that the pH of the water ranged from 4.4 to 7.0. In lakes where the pH was 4.4; 5.1 and 5.8, not a single fish was caught, and in the remaining lakes only individual specimens of lake and rainbow trout and char were found.

Along with the death of lakes, degradation of forests occurs. Although forest soils are less susceptible to acidification than water bodies, the vegetation growing on them reacts extremely negatively to an increase in acidity. Acid precipitation in the form of aerosols envelop the needles and foliage of trees, penetrate into the crown, flow down the trunk, and accumulate in the soil. Direct damage is expressed in a chemical burn of plants, a decrease in growth, a change in the composition of the undergrowth vegetation.

Acid rain damages buildings, pipelines, wrecks cars, reduces soil fertility, and can allow toxic metals to seep into aquifers.

Many monuments of world culture are exposed to the destructive effect of acid precipitation. So, for 25 centuries, the marble statues of the world-famous monument of architecture of Ancient Greece, the Acropolis, were constantly exposed to wind erosion and rain. Recently, the action of acid rain has accelerated this process. In addition, this is accompanied by the deposition of soot crusts on the monuments in the form of sulfur dioxide emitted by industrial enterprises. To connect individual architectural elements, the ancient Greeks used small rods and staples made of iron coated with a thin layer of lead. Thus, they were protected from rust. During the restoration work (1896-1933) steel parts were used without any precautions, and due to the oxidation of iron under the action of an acid solution, extensive cracks form in the marble structures. Rust causes an increase in volume, and the marble cracks.

The results of studies initiated by one of the UN commissions show that acid precipitation also has a detrimental effect on ancient stained glass windows in some Western European cities, which can completely destroy them. More than 100,000 stained glass samples are at risk. Ancient stained glass windows were in good condition until the beginning of the 20th century. However, over the past 30 years, the process of destruction has accelerated, and if the necessary restoration work is not carried out, the stained-glass windows may die in a few decades. Colored glass made in the 8th-17th centuries is at particular risk. This is due to the peculiarities of the production technology.

Acid rain was first recorded in Western Europe, in particular Scandinavia, and North America in the 1950s. Now this problem exists throughout the industrial world and has acquired particular importance in connection with the increased technogenic emissions of sulfur and nitrogen oxides. Within a few decades, the scale of this disaster became so wide, and the negative consequences were so great, that in 1982 a special international conference on acid rain was held in Stockholm, which was attended by representatives of 20 countries and a number of international organizations. Until now, the severity of this problem remains, it is constantly in the focus of attention of national governments and international environmental organizations. On average, the acidity of precipitation, which falls mainly in the form of rain in Western Europe and North America, covers an area of almost 10 million square meters. km, is 5-4.5, and fogs here often have a pH of 3-2.5. In recent years, acid rain has been observed in industrial areas of Asia, Latin America and Africa. For example, in the Eastern Transvaal (South Africa), where 4/5 of the country's electricity is generated, per 1 sq. km falls about 60 tons of sulfur per year in the form of acid precipitation. In tropical regions, where industry is practically undeveloped, acid precipitation is caused by the release of nitrogen oxides into the atmosphere due to the burning of biomass.

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 largely facilitated by the once adopted "policy of high pipes" as an effective means of combating surface air pollution. Almost all countries simultaneously are "exporters" of their own and "importers" of foreign emissions. The "wet" part of the emissions (aerosols) is exported, the dry part of the pollution falls in the immediate vicinity of the emission source or at a small distance from it.

Exchange acid-forming and other air pollutant emissions are typical for all countries of Western Europe and North America. Great Britain, Germany, France send more oxidized sulfur to their neighbors than they receive from them. Norway, Sweden, Finland receive more oxidized sulfur from their neighbors than they release through their own borders (up to 70% of acid rain in these countries is the result of "export" from the UK and Germany). The transboundary transport of acid rain is one of the reasons for the conflict between the US and Canada.

Acid rain and its causes

The term "acid rain" refers to all types of meteorological precipitation - rain, snow, hail, fog, sleet - whose pH is less than the average pH of rainwater (the average pH for rainwater is 5.6). Sulfur dioxide (SO2) and nitrogen oxides (NOx) released during human activity are transformed into acid-forming particles in the earth's atmosphere. These particles react with atmospheric water, turning it into acid solutions, which lower the pH of rainwater. The term "acid rain" was first introduced in 1872 by the English explorer Angus Smith. His attention was drawn to the Victorian smog in Manchester. 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 reservoirs, forests, crops, and vegetation. In addition, acid rain destroys buildings and cultural monuments, pipelines, renders cars unusable, reduces soil fertility and can lead to seepage of toxic metals into aquifers.

Normal rain water is also a slightly acidic solution. This is due to the fact that natural substances in the atmosphere, 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, in real life the acidity of rainwater in one area may differ from the acidity of rainwater in another area. This primarily depends on the composition of gases contained in the atmosphere of a particular area, such as sulfur oxide and nitrogen oxides.

Chemical analysis of acid precipitation shows the presence of sulfuric (H2SO4) and nitric (HNO3) acids. The presence of sulfur and nitrogen in these formulas indicates that the problem is related to the release of these elements into the atmosphere. When fuel is burned, sulfur dioxide enters the air, atmospheric nitrogen also reacts with atmospheric oxygen and nitrogen oxides are formed.

As already mentioned, any rainwater has a certain level of acidity. But in the normal case, this indicator corresponds to a neutral pH level - 5.6-5.7 or slightly higher. A slight acidity is due to the content of carbon dioxide in the air, but it is considered so low that it does not cause any harm to living organisms. Thus, the causes of acid rain are associated exclusively with human activities, and cannot be explained by natural causes.

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, the current level of development of purification technologies does not allow filtering out nitrogen and sulfur compounds that result from the combustion of coal, peat, and other types of raw materials that are used in industry. As a result, such oxides enter the atmosphere, combine with water as a result of reactions under the action of sunlight, and fall to the ground in the form of precipitation, which is called "acid rain".

Ecology

Acid rain, which is described as sulfuric and nitric acids deposited in the atmosphere, is a major environmental problem. Although often associated with rainfall, the term also applies to dry acidic substances. These acids are the result of sulfur dioxide and nitric oxide reacting with moisture and other substances in the atmosphere. While there are natural sources of these chemicals, there is increasing focus on man-made sources such as coal-fired power plants.

What is the danger of acid rain? First, acid rain contributes to the acidification of soil, rivers and lakes, which exceeds the allowable limits for plants and animals, and they also destroy human-made structures. What other effect does acid rain have?

Water oxidation

Water resists rapid changes in pH, a measure of the acidity of a substance, which at low values indicates more acidity. However, even this resistance can be overcome with constant and prolonged exposure to acid rain. Ecosystems of rivers and lakes are especially susceptible to such changes. So, for example, one-day flies die at pH 5.5, while trout and perch can survive in more acidic water. However, with a decrease in the population of dayflies and other insects, the same trout will face a lack of food to maintain their population. Also, at a pH of 5, many fish are unable to hatch and grow 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 high altitude forests, where the trees are often submerged in an acid cloud. Acid rain can also damage trees in a more subtle way, reducing nutrient levels and increasing levels of toxic compounds in the soil.

Cars

Many people go to great lengths to improve the look of their car, but acid rain can literally destroy the protective coating on your vehicle. To combat these effects of acid rain, many car manufacturers have begun to coat their cars with acid-resistant paints.

Building

Limestone and marble structures are particularly susceptible to acid rain. All this is due to the content of the mineral calcite in these materials, which dissolves easily. Damage is easily visible on older stone buildings and monuments where the carvings have corroded 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 acid reacts with.

Human health

Acid rain looks like normal rain without any distinctive taste or sensation. The harm from acid rain to humans is not direct. Walking in acid rain, and even swimming in a lake affected by acid rain, is no more dangerous than swimming in clear water. However, the pollutants that cause acid rain do harm human health. Sulfur dioxide and nitric oxide react with the atmosphere to form pure sulfate and nitrogen particles that are carried long distances by the wind and inhaled into the lungs of humans. Small particles can also get into the house. For example, many studies have found an association 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 fight acid rain is to limit the 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.

Normal rainwater is slightly acidic because the air, where moisture particles form, contains carbon dioxide. But if there is an increased content of pollutants in the atmosphere emitted as a result of the work of cars, metallurgical enterprises, power plants and other human activities, then the water reacts with these compounds, and its pH decreases. It contains sulfuric, nitrous, sulfurous, nitric and other acids. And when 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.

The effects of acid rain

If acid rain is observed in the area of reservoirs - above 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 rains occur regularly, then this stability decreases, as a result, the ecological state of water bodies worsens. With a high concentration of acids in the water, the creatures living in it, most often insects, begin to die. For example, day-flies cannot live at a pH greater than 5.5. Fish are more resistant to such pollution, but if insects die, the chain is inevitably broken: for example, trout that feeds on these, faces a lack of food. As a result, the number of fish in the pond also decreases.

Some fish can exist in acidic water, but cannot grow offspring in it, which also leads to the death of the population.

If acid rain falls on forests, the leaves of the trees break down and fall off. Most often, tall trees that find themselves in acid clouds are exposed to such an effect. Insignificant 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 man-made structures: buildings and monuments made of marble or limestone are literally corroded, as calcite is washed out of them.

Granite and sandy rocks are more resistant to acids.

Acid rain also poses a risk to human health. Outwardly, they cannot be distinguished, 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 when swimming in a river or lake. This leads to an increased risk of cardiovascular diseases, respiratory diseases - asthma, bronchitis, sinusitis.

Tip 2: How dangerous is battery and battery waste

Batteries and accumulators are considered hazardous waste. They are made up of various chemicals that allow them to work through reactions. Some of these substances, such as nickel and cadmium, are highly toxic and can harm people and the environment.

In particular, they can infect water, soil and damage wildlife. Cadmium can harm microorganisms and adversely affect the decomposition of organic matter. It can also accumulate in fish, reducing their numbers and making them unfit for human consumption.

In addition, batteries contain alkaline and acid components, heavy metals (mercury, lithium, lead, zinc, cobalt).

Which batteries are more dangerous - disposable or rechargeable?

Household uses both disposable and rechargeable batteries.

Batteries are used in mobile, laptops, computers, digital video cameras, cameras. They contain environmentally hazardous nickel and cadmium compounds, nickel hydride and lithium.

Disposable batteries are used in flashlights, toys, smoke detectors, wall clocks, calculators, radios, and remote controls. These are alkaline batteries in which a chemical reaction is converted into an electrical one. They contain zinc and manganese. Disposable batteries are less harmful than accumulators, but they are thrown away more often and the volume of waste from them is greater.

What happens to used batteries and accumulators

When they are thrown away with the rest of the trash, batteries and accumulators end up in landfills. Their toxic components penetrate into water and soil, pollute lakes, streams, making water unsuitable for drinking, fishing and swimming. If it rains over such a place, together with the rain water, toxic substances will penetrate deeper into the soil. It will increase the likelihood that they will enter the groundwater.

Some chemicals from batteries and accumulators can react with other trash to form very dangerous compounds.

In some cases, toxic substances can cause serious harm to humans, animals and plants. For example, this happens when a small amount of waste is constantly thrown into the same place, or when a large amount of toxic waste is thrown out at one time.

Humans and animals can be exposed to harmful components through inhalation, ingestion and skin contact. For example, a person may inhale the vapors of polluted water while taking a shower. He can also eat foods contaminated with toxic substances. The most common type of poisoning of the human body with toxic substances occurs due to contaminated drinking water. If a toxic substance enters the skin of a person, infection also occurs.

The consequences of such exposure for human health can be very different, from skin burns in the event of an alkaline battery leaking to chronic diseases.

With constant exposure to toxic substances, diseases such as cancer, liver failure, and delayed development and growth in children can develop. The danger from toxic substances also lies in the fact that some of them accumulate in the body, manifesting themselves not immediately. When their number reaches a critical level, serious health problems arise.

Problem history

The impact of precipitation with a low water index on the environment was identified more than a hundred years ago by the British chemist R. Smith. The scientist was 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. His colleague spoke again about the hydrogen index 10 years later.

The chemist and engineer S. Arrhenius published a report on chemicals that can donate a hydrogen cation. He again drew the attention of scientists to the harmfulness of such precipitation, to what danger the phenomenon poses, and became the man who introduced 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 acid components. This substance is monobasic acids (sulfuric and nitric). Precipitation based on interacting gases (chlorine and methane) is less common. What they will be in composition depends on what chemical waste is in combination with water.

In short, the mechanism for the formation of the phenomenon is the combination of oxides that have entered the atmosphere with water molecules. During the interaction, the formation of chemical components - sulfuric and nitric acid.

Reasons for the appearance

Low pH hydrometeors are caused by elevated concentrations of sulfur and nitrogen oxides in the atmosphere. Compounds enter the atmosphere naturally or artificially created by man. Natural sources are:

The main reason is human activity. What is it? The factor that causes precipitation is air pollution. The most well-known pollutants are road transport and thermal power plants. A significant role in the occurrence of oxides in the atmosphere is played by the release of industrial enterprises, nuclear tests. Hydrometeors with acid are formed in large quantities in places where space rockets are launched.

Cosmodrome Vostochny. Launch of Soyuz-2.1b launch vehicle with 19 satellites

Hydrometeors with acids are not only snow or fog, but also dust clouds. They form when toxic 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 can be called chemical production, oil and gasoline storage facilities, solvents 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. The gases rise into the air and cause oxidation. One of the reasons is nitrogen compounds released during the production of materials for the construction, construction of buildings, road construction. They also often result in low pH precipitation.

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 poisonous acid rainfall in the form of fog.

The facts about such precipitation say that the problem of acid rain has existed for millions of years. On Earth, their influence is known from the prehistoric period. Almost 300 million years ago, the formation of acid rain led to the extinction of 90 percent of species.

Consequences for nature

Precipitation with a low pH level poses a risk of global disturbances in the biosphere. What harm do they do? Ecologists say about the negative consequences of these precipitations:

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 noted in Denmark, Sweden, Norway and Finland. Why do the Scandinavian countries suffer the most? There are several reasons for this. First, wind-driven sulfur formations from Central Europe and Britain. Secondly, limestone-poor lakes contribute to acid rain. Reservoirs do not have much capacity to neutralize acids.

In Russia, acid precipitation is becoming more active every year. Environmentalists are sounding the alarm. The atmosphere above megacities is oversaturated with chemical elements and hazardous substances. Especially often acid rain and smog over large cities fall 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 over the past 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 is not the best in Kazakhstan. 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 noted in all countries without exception. As a result of their loss, not only the environment suffers. Chronic diseases such as allergies and asthma are exacerbating 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 increase the number of oncological tumors. The main cause of precipitation is harmful emissions, which a person is not able to avoid. That is why doctors do not advise getting caught 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.

Allergies and asthma affect children, young people, and older people

If you ask a question: what are the areas where acid rain most often forms? The answer to it is quite simple: in the places of greatest concentration of various industries and vehicles. However, it is not so easy to designate an area that is top in this regard. Why is acid rain dangerous? The fact that due to the wind changing its direction, precipitation can fall many kilometers from the 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. There is a lot of talk about how to deal with acid rain, but the size 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 cardinal and quick solution. Many scientists and environmentalists believe that due to the development of the modern economy, it is generally impossible to do this. 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 man. 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 dealing with acid rain are used:

reducing the sulfur content in fuel reduces the causes of acid precipitation;
the operation of high pipes at enterprises is a modern way to solve the problem;
technological improvement 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 so far there is 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.