The main soil pollutants

Soil - the top layer of land formed under the influence of plants, animals, microorganisms and climate from the parent rocks on which it is located. This is an important and complex component of the biosphere, closely related to other parts of it.

зп1

There are several stages in the development and formation of the soil. Young soils are usually the result of weathering of parent rocks or the transfer of sediment deposition (for example, alluvium). Microorganisms, pioneer plants - lichens, mosses, grasses, and small animals-settle on these substrates. Gradually, other plant and animal species are introduced, the composition of the biocenosis becomes more complex, and a whole series of relationships arise between the mineral substrate and living organisms. As a result, Mature soil is formed, the properties of which depend on the original parent rock and climate. The process of soil development ends when the balance is reached, the correspondence of the soil with the vegetation cover and climate. The soil is like a living organism, within which various complex processes take place. In order to keep the soil in good condition, it is necessary to know the nature of the metabolic processes of all its components. The soil is home to a great variety of different living organisms: bacteria, micro-fungi, algae, protozoa, mollusks, arthropods and their larvae, earthworms, and many others. All these organisms play a huge role in shaping the soil and changing its physical and chemical characteristics.

In artificial ecosystems, this cycle is disrupted, as people withdraw a significant part of agricultural products, using it for their own needs. Due to the non-participation of this part of the product in the cycle, the soil becomes barren. To avoid this and increase soil fertility in artificial ecosystems, people contribute organic and mineral fertilizers.

Soil pollution

зп2

Under normal natural conditions, all processes occurring in the soil are in equilibrium. But often a person is guilty of disturbing the equilibrium state of the soil. As a result of the development of human economic activity, there is pollution, changes in the composition of the soil and even its destruction. And these small areas continue to shrink due to inept human economic activity. Vast areas of fertile land are lost in mining operations, in the construction of enterprises and cities. Destruction of forests and natural grass cover, repeated plowing of the land without observing the rules of agricultural technology leads to soil erosion - destruction and washing away of the fertile layer by water and wind. One of the consequences of increasing human production activity is the intensive pollution of the soil cover. The main soil pollutants are metals and their compounds, radioactive elements, as well as fertilizers and pesticides used in agriculture. The most dangerous soil pollutants include mercury and its compounds. Mercury enters the environment with toxic chemicals, industrial waste containing metallic mercury and its various compounds. Lead contamination of soils is even more widespread and dangerous. Lead compounds are used as additives to gasoline, so vehicles are a serious source of lead pollution. Especially a lot of lead in soils along major highways. Near major centers of ferrous and non-ferrous metallurgy, soils are contaminated with iron, copper, zinc, manganese, Nickel, aluminum, and other metals. In many places, their concentration is ten times higher than the MPC. Radioactive elements can enter the soil and accumulate in it as a result of precipitation from nuclear explosions or when removing liquid and solid waste from industrial enterprises, nuclear power plants or research institutions associated with the study and use of nuclear energy.

зп3

Modern agriculture has a significant impact on the chemical composition of soils, which widely uses fertilizers and various chemicals to control pests, weeds and plant diseases. Currently, the amount of substances involved in the cycle in the process of agricultural activity is about the same as in the process of industrial production. Persistent organic compounds used as pesticides are particularly dangerous. They accumulate in the soil, water, and bottom sediments of reservoirs.

зп4

Heavy metals enter the soil mainly from the atmosphere with emissions from industrial enterprises. If soils are contaminated with heavy metals and radionuclides, then it is almost impossible to clean them. So far, the only way is known: to sow such soils with fast-growing crops, giving a large green mass; such crops extract toxic elements from the soil, and then the harvested crop must be destroyed. But this is a rather lengthy and expensive procedure. It is possible to reduce the mobility of toxic compounds and their entry into plants by increasing the pH of soils by liming or adding large doses of organic substances, such as peat. A good effect can be obtained by deep plowing, when the top contaminated soil layer is plowed to a depth of 50 - 70 cm when plowing, and the deep soil layers are raised to the surface. To do this, you can use special multi-tier plows, but at the same time the deep layers still remain contaminated. Finally, on soils contaminated with heavy metals (but not radionuclides), crops that are not used as food or feed, for example, flowers, can be grown.