Air pollution

Air pollution is one of the main problems all over the world. Millions of chimneys, buses, cars, plants, factories and other industrial enterprises exhaust fumes and harmful substances into the atmosphere. Poisoned air is the main reason why it is hard to breathe in large cities with big amount of plants and transport (example – Nijnij Tagil in the Urals).

Human activity has been increasing the concentration of such gases like carbon dioxide; methane, nitrous oxide-and water vapor in the atmosphere. Scientists expect to see a doubling of carbon dioxide over pre-industrial levels around the year 2065. Every year the atmosphere is polluted by about one thousand (1000) tons of industrial dust. Among industries especially toxic wastes are made by enterprises of colour metallurgy, chemical, petrochemical, black metallurgy, woodworking, pulp paper industry etc. Big cities suffer from smog.

«Leaders» of wastes of harmful substances in atmosphere in Russia during three last years are Krasnoyarsk region, the Tyumen, Sverdlovsk, Chelyabinsk, Kemerovo area and it is necessary to attribute this areas to a zone of the ecological catastrophe. The most contaminated regions are economic centers of Russian Federation and most populated. Now 2/3 population of Russia continues to live in conditions of dangerous air contamination. Various chemical elements are intensively absorbed by our organism during breathing, it is harmful for our health. Air pollution is especially harmful for quality of genofond.

Scientists say that air pollution is the cause of acid rains, global warming and of greenhouse effect.

Acid rains

First of all I should say that the only place on earth where pure water is found is in a laboratory. Rainwater always contains small amounts of impurities. These impurities come from dust particles or are absorbed from the gases in the air. If pure water is exposed to the air it absorbs carbon dioxide to form carbonic acid and becomes slightly acidic, dropping from pH 7 i.e. neutral, to pH 5,6. Even in remote, unpopulated areas rain can reach a pH of 4,5. However, a pH of less than 4, 5 in rain is almost certainly caused by air pollution.

Acid rain is caused by the release of the sulphur dioxide and nitrous oxides. The main sources of sulphur dioxide are coal-fired power stations and metal working industries.

The main sources of nitrous oxides emissions are vehicles and fuel combustion. Sulphurdioxide reacts with water vapor and sunlight to form sulphuric acid. Likewise nitrous oxides form nitric acid in the air. These reactions take hours, or even days, during which polluted air may move hundreds of kilometers. Thus acid rain can fall far from, the source of pollution.

When mist or fog droplets condense they will remove pollutants from the air andcan become more strongly acid than acid rain. Even snow can be acid. Gases and particles, not dissolved in water, with a low pH can also be deposited directly onto soil, grass and leaves. It impossible that even more acidity is deposited in this way than by rain! Not much is known about this process, and it is particularly difficult to study. There are some undoubted effects of acid rains:

• Acid rains can increase the acidity of lakes, dams and streams and cause the death of aquatic life.

• Acid rain can increase the acidity of soil, water and shallow groundwater.

• Acid rain has been linked with the death of trees in Europe and North America.

In spite of a great deal of research, no one yet knows exactly how acid rain
harms forests. Most of the forests of Europe consist of huge areas of one tree
species. This encourages the spread of plant pests and diseases. It seems likely
that acid rain weakens the trees, perhaps helped by other pollutants such as
ozone, and then leaves the trees open to attack by disease. Acid rain also
disrupts the availability of soil nutrients. The final death of a tree may result
from a combination of stresses such as heat, cold, drought, nutrient disruption
and disease.

• Acid rains erode buildings and monuments.

• Acid particles in the air are suspected of contributing to respiratory problems of people.

Scientists have many ways to solve this environmental problem. We need to use energy more efficiently at home, in ourvehicles and in industry. We will have to think hard about alternative energy sources. It is possible to remove acidic emissions from coal burning, but this is very expensive. It may be possible to breed crops and trees that resist pollution, but this would only be a partial solution. In practice we will probably need a combination of all these ideas and innovations.

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