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Acid rain hotspots are places where the amount of acid rain negatively affects the stability of an ecosystem. An example of acid rain is any more acidic precipitation than biological levels. Acid rain is formed when SO₂ and N₂O industrial emissions combine with atmospheric moisture to produce sulfuric and nitric acids.
When analyzing the composition of acid rain, the main focus is on the content of hydrogen cations that determine its acidity (pH). For pure water, the pH = 7, which corresponds to a neutral reaction. Solutions with a pH below 7 are acidic and those with a higher pH are alkaline. Accordingly, the pH of acid rain tends to be low values. The mechanism of the formation of acid rain is associated with pollutants penetrating the lower atmospheric layers and lingering in them.
The main component of precipitation with increased acidity, as studies have shown, is sulfur oxide. In the atmosphere, as a result of the photochemical oxidative reaction, some of it is transformed into sulfuric anhydride, and it, in turn, in contact with water vapor, turns into sulfuric acid. The rest of the sulfur oxide is converted into sulfuric acid, which, when oxidized by high humidity, gradually becomes sulfuric acid.
The causes of acid rain are numerous, and the main ones are listed below:
● The main cause is the exhaust from gasoline-fueled vehicles. As a result of fuel combustion, the vapors rush into the atmosphere and, reacting with water, significantly increase the acidity of precipitation.
● The activities of thermal power plants. With the combustion of various fuels used to generate heat, there are constant emissions of harmful substances into the atmosphere.
● Acid rain is associated with the active extraction, processing, and use of minerals such as coal, ore, gas, and others. They are used by mankind for a long time, and few people think about the damage caused by the combustion of fuel, which causes the release of large amounts of carbon dioxide and various pollutants.
● Among the reasons for the formation of acid rain can be noted as natural, that is, not dependent on humans, but related to natural phenomena and processes. Thus, during volcanic eruptions, many compounds are emitted and released into the atmosphere, such as sulfur oxides, sulfates, and hydrogen sulfides. Also, emissions are caused by lightning discharges and the activity of microorganisms living in the soil.
● Hotspots of acid rain are also formed by the decomposition of animal and plant corpses. During these processes, nitrogen- and sulfur-containing compounds are produced which, when they enter the atmospheric layers and react with the moisture, turn into acids.
● Among the causes of acid rain should be highlighted are the activities of various industrial and processing enterprises engaged in metal processing, production of metal parts, and mechanical engineering. Many factories and plants do not use purification and filtration facilities, so harmful emissions enter the environment and strongly pollute it.
● Another reason why acid rain forms are the active use by people of various aerosols and sprays that contain hydrogen chloride and other equally harmful compounds.1. Effects of acid rain on water bodies and organisms that live in the water.
As a rule, the pH of most rivers and lakes is from 6 to 8, but when their waters contain high levels of minerals and organic acids, the pH is much lower.
All living things are sensitive to changes in pH, so increasing the acidity of water bodies causes irreparable damage to fish stocks. In Canada, for example, because of frequent acid rains, more than 4,000 lakes have been declared dead, and 12,000 more are on the verge of death. The biological balance of 18 thousand of lakes in Sweden is disturbed. Fish disappeared in half of the lakes in southern Norway.
Due to the death of phytoplankton, sunlight penetrates to a greater depth than usual. That is why all the lakes that have died of acid rain are strikingly clear and unusually blue.
2. Effects of acid rain on forests.
Acid rain causes great damage to forests, gardens, and parks. Leaves fall, and young shoots become brittle 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 nearly a third of all spruces. In wooded areas such as Bavaria and Baden, up to half of the forest land is affected. Acid rain does not only damage forests in the plains; several damages have been recorded in the high mountain forests of Switzerland, Austria, and Italy. Soil acidification is considered one of the negative factors leading to the degradation of temperate forests in the northern hemisphere. At the same time, the effect can manifest itself long after acid precipitation.
3. Effects of acid rain on soil.
It has been established that the effects of acid rain on the soil and crops are determined not only by their acidity and cationic composition but also by the duration and air temperature. Under the influence of acid precipitation, not only the nutrients vital for plants are leached from the soil, but also toxic heavy and light metals - lead, cadmium, aluminum, etc. Subsequently, they or the resulting toxic compounds are assimilated by plants and other soil organisms, which leads to very negative consequences.