A soil pollutant can be any physical agent, chemical substance and biological species that enters or occurs in the environment in amounts exceeding its normal concentration. The main indicator characterizing the impact of pollutants on the environment is the maximum permissible concentration (MPC).
Pollution of soils is associated with atmospheric and water pollution. Various solid and liquid wastes of industrial production, agriculture and municipal and domestic enterprises get into the soil. The main sources of pollution are houses and public utility companies, industrial enterprises, agriculture, transport.
Housing and communal economy
The main pollutants of soil are household waste, food waste, construction waste, waste heating systems, household items that have fallen into disrepair, garbage of public institutions (hospitals, canteens, hotels, stores).
All of this is collected and taken to municipal and local landfills, which occupy large areas of land and are sources of air and groundwater pollution by toxic substances. At present, the destruction of housing and communal waste is done by industrial processing of garbage at special factories.
Industrial enterprises
Solid and liquid industrial waste constantly contains some or other substances that can have a toxic effect on the soil, living organisms and their communities. For example, metallurgical waste contains salts of non-ferrous and heavy metals. The machine-building industry discharges cyanide, arsenic and beryllium compounds into the environment. Benzene and phenol wastes are produced in the production of plastics and man-made fibers. Waste from the pulp and paper industry, provide phenols, methanol, turpentine.
The main pathway of heavy metals into the soil is atmospheric. The greatest concentration in atmospheric emissions of enterprises have such metals as cadmium, mercury, lead, zinc, copper, nickel.
Agriculture
The main pollutants of the soil in this industry are fertilizers, pesticides used to protect plants from pests, diseases, weeds. Millions of tons of nutrients (nitrogen, potassium, phosphorus, magnesium, calcium, etc.) are removed from the soil each year with the harvest, which must be compensated. Therefore, the application of organic and mineral fertilizers – the most important means of restoring soil fertility. The need for pesticides in agriculture is explained by the fact that without them the crop yield drops sharply and is only 20-40% of what could have been obtained with their use. However, we should know that a large number of pesticides are toxic not only to pests of cultivated plants, but also to animals and humans. Unregulated use of pesticides leads to soil contamination due to the disruption of the cycle of substances in it. The peculiarity of these substances is that they remain stable in the soil for a long time, which leads to their accumulation in the harvest of crops.
The use of fertilizers in agriculture also causes a number of environmental problems associated with soil contamination by inorganic and organic chemicals. The accumulation of cadmium in the soil, which is naturally found in soil and water, as well as in plant tissues, poses a great danger to humans.
Organic fertilizers are often a source of biological soil contamination. Together with manure, pathogenic bacteria, helminth eggs and other harmful organisms enter it, which can enter the human body through food.
Transportation
Developed transport network, its progress is accompanied by negative consequences – negative impact on the environment. Environmental damage from the operation of motor vehicles is caused by toxic emissions. Thus, it has been established that every year motor vehicles emit into the atmosphere more than 12 million tons of various pollutants: carbon monoxide, nitrogen oxides, sulfur, soot and others. Most of these emissions are deposited on the soil, changing its basic natural parameters.