Heavy metals in soils. Sources of soil pollution with heavy metals Soil pollution with heavy metals is maximum in the territory

Heavy metals (HMs) are already ranked second in terms of danger, behind pesticides and well ahead of such well-known pollutants as carbon dioxide and sulfur. In the future, they may become more dangerous than nuclear power plant waste and solid waste. HM contamination is associated with their widespread use in industrial production. Due to imperfect purification systems, HMs enter the environment, including the soil, polluting and poisoning it. HMs are special pollutants, the monitoring of which is obligatory in all environments.

Soil is the main medium into which HMs enter, including from the atmosphere and the aquatic environment. It also serves as a source of secondary pollution of surface air and waters that enter the World Ocean from it.

HMs are absorbed from the soil by plants, which then get into food.

The term "heavy metals", which characterizes a wide group of pollutants, has recently become widely used. In various scientific and applied works, the authors interpret the meaning of this concept in different ways. In this regard, the number of elements assigned to the group of heavy metals varies over a wide range. Numerous characteristics are used as membership criteria: atomic mass, density, toxicity, prevalence in the natural environment, the degree of involvement in natural and technogenic cycles.

In works devoted to the problems of environmental pollution and environmental monitoring, today more than 40 elements of D.I. Mendeleev with an atomic mass of more than 40 atomic units: V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Mo, Cd, Sn, Hg, Pb, Bi, etc. According to the classification of N. Reimers, heavy metals should be considered with with a density of more than 8 g/cm3. At the same time, the following conditions play an important role in the categorization of heavy metals: their high toxicity to living organisms in relatively low concentrations, as well as their ability to bioaccumulate and biomagnify. Almost all metals that fall under this definition (with the exception of lead, mercury, cadmium and bismuth, the biological role of which is not clear at the moment), are actively involved in biological processes, are part of many enzymes.

The most powerful suppliers of metal-enriched wastes are non-ferrous metal smelting enterprises (aluminum, alumina, copper-zinc, lead-smelting, nickel, titanium-magnesium, mercury, etc.), as well as non-ferrous metal processing (radio engineering, electrical engineering, instrument-making, galvanic, etc.).

In the dust of metallurgical industries, ore processing plants, the concentration of Pb, Zn, Bi, Sn can be increased compared to the lithosphere by several orders of magnitude (up to 10-12), the concentration of Cd, V, Sb - tens of thousands of times, Cd, Mo, Pb, Sn, Zn, Bi, Ag - hundreds of times. Wastes from non-ferrous metallurgy enterprises, paint and varnish factories and reinforced concrete structures are enriched with mercury. The concentrations of W, Cd, and Pb are increased in dust from machine-building plants (Table 1).

Table 1. Main technogenic sources of heavy metals

Under the influence of metal-enriched emissions, areas of landscape pollution are formed mainly at the regional and local levels. The influence of energy enterprises on environmental pollution is not due to the concentration of metals in waste, but to their huge amount. The mass of waste, for example, in industrial centers, exceeds their total amount coming from all other sources of pollution. A significant amount of Pb is released into the environment with car exhaust gases, which exceeds its intake with waste from metallurgical enterprises.

Arable soils are polluted with elements such as Hg, As, Pb, Cu, Sn, Bi, which enter the soil as part of pesticides, biocides, plant growth stimulants, structure formers. Non-traditional fertilizers made from various waste products often contain a wide range of contaminants at high concentrations. Of the traditional mineral fertilizers, phosphate fertilizers contain impurities of Mn, Zn, Ni, Cr, Pb, Cu, Cd.

The distribution in the landscape of metals released into the atmosphere from technogenic sources is determined by the distance from the pollution source, climatic conditions (strength and direction of winds), terrain, and technological factors (the state of waste, the way waste enters the environment, the height of the pipes of enterprises).

HM dissipation depends on the height of the source of emissions into the atmosphere. According to M.E. Berland, with high chimneys, a significant concentration of emissions is created in the surface layer of the atmosphere at a distance of 10-40 chimney heights. Six zones are distinguished around such pollution sources (Table 2). The area of influence of individual industrial enterprises on the adjacent territory can reach 1000 km2.

Table 2. Zones of soil contamination around point sources of pollution

	Distance from pollution source in km	Excess of HM content in relation to the background
Security zone of the enterprise

Soil pollution zones and their size are closely related to the vectors of the prevailing winds. The relief, vegetation, urban buildings can change the direction and speed of movement of the surface layer of air. Similarly to the zones of soil pollution, zones of vegetation cover pollution can also be distinguished.

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FEDERAL STATE BUDGETARY EDUCATIONAL INSTITUTION OF HIGHER EDUCATION "OMSK STATE TECHNICAL UNIVERSITY"

Department of Industrial Ecology and Safety

"Problems of soil pollution with heavy metals and possible solutions"

Completed:

Fomin A., Melnikov D., Lamazhap A.

students gr. TB-161

Checked:

Kholkin E.G., Ph.D.

Introduction
Conclusion
Bibliography
Introduction
The soil is an invaluable natural wealth that provides a person with the necessary food resources. Nothing can replace the soil cover: without this colossal natural object, life on earth is impossible. At the same time, today one can observe the improper use of the soil, which leads to an increase in its pollution and, as a result, a decrease in its fertile properties. Humanity should already seriously think about the problem of soil pollution and take the necessary measures to protect it.
The soil is an indicator of the general technogenic situation. Pollution enters the soil with atmospheric precipitation, surface waste. They are also introduced into the soil layer by soil rocks and groundwater. The group of heavy metals includes all non-ferrous metals with a density exceeding the density of iron. The paradox of these elements is that they are necessary in certain quantities to ensure the normal functioning of plants and organisms.
But their excess can lead to serious illness and even death. The food cycle causes harmful compounds to enter the human body and often cause great harm to health. Sources of heavy metal pollution are industrial enterprises.
Soil protection is very important. Constant control and monitoring does not allow growing agricultural products and grazing livestock on contaminated lands.
The purpose of the work is to consider the problems of soil pollution with heavy metals and possible ways to solve them.
1. Soil pollution with heavy metals
Heavy metals (HMs) are already ranked second in terms of danger, behind pesticides and well ahead of such well-known pollutants as carbon dioxide and sulfur. In the future, they may become more dangerous than nuclear power plant waste and solid waste. HM contamination is associated with their widespread use in industrial production. Due to imperfect purification systems, HMs enter the environment, including the soil, polluting and poisoning it. HMs are special pollutants, the monitoring of which is obligatory in all environments.
Soil is the main medium into which HMs enter, including from the atmosphere and the aquatic environment. It also serves as a source of secondary pollution of surface air and waters that enter the World Ocean from it.
HMs are absorbed from the soil by plants, which then get into food.
The term "heavy metals", which characterizes a wide group of pollutants, has recently become widely used. In various scientific and applied works, the authors interpret the meaning of this concept in different ways. In this regard, the number of elements assigned to the group of heavy metals varies over a wide range. Numerous characteristics are used as membership criteria: atomic mass, density, toxicity, prevalence in the natural environment, the degree of involvement in natural and technogenic cycles.
In works devoted to the problems of environmental pollution and environmental monitoring, today more than 40 elements of D.I. Mendeleev with an atomic mass of more than 40 atomic units: V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Mo, Cd, Sn, Hg, Pb, Bi, etc. According to the classification of N. Reimers, heavy metals should be considered with with a density of more than 8 g/cm3. At the same time, the following conditions play an important role in the categorization of heavy metals: their high toxicity to living organisms in relatively low concentrations, as well as their ability to bioaccumulate and biomagnify. Almost all metals that fall under this definition (with the exception of lead, mercury, cadmium and bismuth, the biological role of which is not clear at the moment), are actively involved in biological processes, are part of many enzymes.
The most powerful suppliers of metal-enriched wastes are non-ferrous metal smelting enterprises (aluminum, alumina, copper-zinc, lead-smelting, nickel, titanium-magnesium, mercury, etc.), as well as non-ferrous metal processing (radio engineering, electrical engineering, instrument-making, galvanic, etc.).
In the dust of metallurgical industries, ore processing plants, the concentration of Pb, Zn, Bi, Sn can be increased compared to the lithosphere by several orders of magnitude (up to 10-12), the concentration of Cd, V, Sb - tens of thousands of times, Cd, Mo, Pb, Sn, Zn, Bi, Ag - hundreds of times. Wastes from non-ferrous metallurgy enterprises, paint and varnish factories and reinforced concrete structures are enriched with mercury. The concentrations of W, Cd, and Pb are increased in dust from machine-building plants (Table 1).
Table 1. Main technogenic sources of heavy metals

Under the influence of metal-enriched emissions, areas of landscape pollution are formed mainly at the regional and local levels. The influence of energy enterprises on environmental pollution is not due to the concentration of metals in waste, but to their huge amount. The mass of waste, for example, in industrial centers, exceeds their total amount coming from all other sources of pollution. A significant amount of Pb is released into the environment with car exhaust gases, which exceeds its intake with waste from metallurgical enterprises.
Arable soils are polluted with elements such as Hg, As, Pb, Cu, Sn, Bi, which enter the soil as part of pesticides, biocides, plant growth stimulants, structure formers. Non-traditional fertilizers made from various waste products often contain a wide range of contaminants at high concentrations. Of the traditional mineral fertilizers, phosphate fertilizers contain impurities of Mn, Zn, Ni, Cr, Pb, Cu, Cd.
The distribution in the landscape of metals released into the atmosphere from technogenic sources is determined by the distance from the pollution source, climatic conditions (strength and direction of winds), terrain, and technological factors (the state of waste, the way waste enters the environment, the height of the pipes of enterprises).
HM dissipation depends on the height of the source of emissions into the atmosphere. According to M.E. Berland, with high chimneys, a significant concentration of emissions is created in the surface layer of the atmosphere at a distance of 10-40 chimney heights. Six zones are distinguished around such pollution sources (Table 2). The area of influence of individual industrial enterprises on the adjacent territory can reach 1000 km2.
Table 2. Zones of soil contamination around point sources of pollution

	Distance from pollution source in km	Excess of HM content in relation to the background
Security zone of the enterprise

Soil pollution zones and their size are closely related to the vectors of the prevailing winds. The relief, vegetation, urban buildings can change the direction and speed of movement of the surface layer of air. Similarly to the zones of soil pollution, zones of vegetation cover pollution can also be distinguished.
2. Migration of heavy metals in the soil profile
The accumulation of the main part of pollutants is observed mainly in the humus-accumulative soil horizon, where they are bound by aluminosilicates, non-silicate minerals, organic substances due to various interaction reactions. The composition and amount of elements retained in the soil depend on the content and composition of humus, acid-base and redox conditions, sorption capacity, and intensity of biological absorption. Some of the heavy metals are firmly retained by these components and not only do not participate in migration along the soil profile, but also do not pose a danger to living organisms. Negative environmental consequences of soil pollution are associated with mobile metal compounds.
Within the soil profile, the technogenic flow of substances encounters a number of soil-geochemical barriers. These include carbonate, gypsum, illuvial horizons (illuvial-ferruginous-humus). Some of the highly toxic elements can transform into compounds that are difficult for plants to access, while other elements that are mobile in a given soil-geochemical setting can migrate in the soil layer, representing a potential hazard to biota. The mobility of elements is largely dependent on the acid-base and redox conditions in soils. In neutral soils, Zn, V, As, Se compounds are mobile, which can be leached during seasonal wetting of soils.
The accumulation of mobile compounds of elements that are especially dangerous for organisms depends on the water and air regimes of soils: their smallest accumulation is observed in permeable soils of the leaching regime, it increases in soils with a non-leaching regime and is maximum in soils with an effusion regime. With evaporative concentration and alkaline reaction, Se, As, V can accumulate in the soil in an easily accessible form, and under conditions of a reducing environment, Hg in the form of methylated compounds.
However, it should be borne in mind that under the conditions of the leaching regime, the potential mobility of metals is realized, and they can be taken out of the soil profile, being sources of secondary pollution of groundwater.
In acidic soils with a predominance of oxidizing conditions (podzolic soils, well drained), heavy metals such as Cd and Hg form easily mobile forms. On the contrary, Pb, As, Se form low-mobility compounds that can accumulate in humus and illuvial horizons and negatively affect the state of soil biota. If S is present in the composition of pollutants, a secondary hydrogen sulfide environment is created under reducing conditions, and many metals form insoluble or slightly soluble sulfides.
Mo, V, As, and Se are present in waterlogged soils in inactive forms. A significant part of the elements in acidic waterlogged soils is present in relatively mobile and dangerous forms for living matter; such are the compounds of Pb, Cr, Ni, Co, Cu, Zn, Cd and Hg. In slightly acidic and neutral soils with good aeration, hardly soluble Pb compounds are formed, especially during liming. In neutral soils, Zn, V, As, Se compounds are mobile, while Cd and Hg can be retained in the humus and illuvial horizons. As alkalinity increases, the risk of soil contamination with these elements increases.
3. Directions for combating soil pollution with heavy metals
3.1 Conducting soil monitoring of the state of the soil
Among the controlled indicators of the state of soils, two groups are distinguished: pedochemical and biochemical. Pedochemical indicators include those soil properties, the change of which can be caused by pollutants and which can adversely affect living organisms. Pedochemical indicators include indicators of the most important chemical properties of soils: humus state, acid-base and cation-exchange properties, in some cases, redox properties of soils.
Biochemical indicators include indicators that characterize the accumulation of pollutants in soils and their direct negative impact on living organisms. The group of biochemical indicators includes: 1) the total content of pollutants, 2) the content of compounds of pollutants with real and potential mobility.
Indicators of the total (gross) content of controlled elements of both natural and technogenic origin characterize their stock in soils (Table 3). Determination of the total content of chemical elements in soils is laborious and requires the complete decomposition of aluminosilicates, which retain a significant part of the compounds, especially in uncontaminated soils (sample melting, decomposition by acids with the participation of hydrofluoric acid).
When assessing the state of contaminated soils, the total content of chemical elements is a less informative indicator. There are quite a lot of data on the natural level of the total content of heavy metals (Hg, Pb, Cd, As, Zn, Cu, etc.) in the soils of the world, in the upper horizons of different soil types in Russia. In addition, the features of the regional background content of many elements have been established, as well as patterns of changes in their quantity depending on the particle size distribution, soil humus content, environmental reaction, the content of elements in soil-forming rocks, and other factors.
Table 3. Background content of gross forms of heavy metal compounds in soils (mg/kg)

		Element, mg/kg

Sod-podzolic sandy and sandy loam
Soddy-podzolic loamy and clayey
gray forest
Chernozems
chestnut

With the expansion of environmental monitoring of the state of soils, methods for determining the content of acid-soluble (1 N HCI, 1 N HNO3) HM compounds began to be widely used. Often they are given the name "conditional gross content of HM". The use of dilute solutions of mineral acids as reagents does not ensure complete decomposition of the sample, but it allows the main part of the compounds of chemical elements of technogenic origin to be transferred into the solution.
The mobile forms of HM include elements and compounds of the soil solution and the solid phase of the soil, which are in a state of dynamic equilibrium with the chemical elements of the soil solution. To determine mobile HMs in soils, weakly saline solutions are used as an extractant, with an ionic strength close to the ionic strength of natural soil solutions: (0.01-0.05 M CaCI2, Ca(NO3)2, KNO3). The content of potentially mobile compounds of controlled elements in soils is determined in an extract of 1 N. NH4CH3COO at different pH values. This extractant is also used with the addition of complexing agents (0.02-1.0 M EDTA).
For analysis, most often, the upper layers of the soil (0-10 cm) are selected, sometimes the distribution of pollutants in the soil profile is analyzed. The upper horizons play the role of a geochemical barrier to the flow of substances coming from the atmosphere. Under the conditions of the leaching water regime, pollutants can penetrate deep into and accumulate in illuvial horizons, which also serve as geochemical barriers.
heavy metal earth reclamation
3.2 Reclamation of lands contaminated with heavy metals
Soil pollution with heavy metals leads to the formation of an acidic or alkaline reaction of the soil environment, a decrease in the exchange capacity of cations, loss of nutrients, a change in density, porosity, reflectivity, the development of erosion, deflation, a reduction in the species composition of vegetation, its suppression or complete death. .
Before starting the reclamation of such lands, it is necessary to establish the source and causes of pollution, take measures to reduce emissions, localize or eliminate the source of pollution. Only under such conditions can high efficiency of reclamation work be achieved.
The guideline for the development of the scope of work on land reclamation is primarily a priority substance that causes deterioration of the ecological state of soils and the quality of agricultural products, and the expected mobility of other hazardous substances should be regulated by special or complex measures.
Reclamation of lands contaminated with heavy metals is carried out using the following methods:
1) Cultivation of pollution-resistant cultivated and wild plants. On the contaminated agricultural lands, the reorganization and reorientation of agricultural production is carried out through the introduction of a new structure of crop production, which ensures the production of quality products. In areas with an ecological emergency with a multi-element set of pollutants, it is advisable to switch from vegetable production to grain-forage crop rotations and the development of animal husbandry with a special regime for keeping animals, for example, with stall and feeding with diluted feed or pasture on polluted and clean meadows.
The transition to other agricultural crops is determined by their different responsiveness to the level of metal content in the soil, and this responsiveness in plants is manifested both depending on the species, variety, and the distribution of metals in the vegetative and regenerative organs. Different accumulation of heavy metals in plants is caused by the existence of biological barriers in the system: soil - root - stem (leaves) - regenerative organ. Usually, the greatest accumulation of heavy metals is observed in vegetative organs, the smallest - in regenerative ones, for example, when the content of lead in the soil is 800 mg/kg, 9 mg/kg was found in rye straw, and 0.9 mg/kg in grain. The responsiveness of plants to certain metals can be traced on the example of cadmium, the most sensitive to an excess of cadmium are soybean, lettuce, spinach, and the most resistant are rice, tomato, cabbage.
Taking into account the specific conditions on soils contaminated with heavy metals, the following resistant crops can be grown: cereals, cereal grasses, potatoes, cabbage, tomatoes, cotton, sugar beets.
2) Soil reclamation with the help of plants (phytorecultivation) capable of accumulating heavy metals in vegetative organs. It has been established that a tree during the growing season along the road is able to accumulate an amount of lead equal to its content in 130 kg of gasoline, therefore, in settlements with polluted areas, it is advisable to collect and dispose of leaf litter. To clean soils from zinc, lead and cadmium, it is necessary to grow a large knotweed, from lead and chromium - mustard, from nickel - buckwheat, etc. (Table 5), in case of contamination with radioactive isotopes, vetch, peas, alfalfa, and shag can be used.
3) Regulation of the mobility of heavy metals in the soil. The absorption of heavy metals by plants depends on the content of their mobile forms in the soil. The existence of mobile forms is determined by the properties and fertility of soils, biogeochemical processes, the intensity and volumes of heavy metals entering the soil, and removal by plants. The behavior of heavy metals in soil and ways to manage their content follow from the theory of geochemical barriers, and the reclamation of contaminated soils is reduced to the creation of additional barriers, the management of existing barriers, or the weakening of some of them.
Soils that are heavy in mechanical composition and have high fertility contain less mobile forms of heavy metals than soils that are light and unproductive. Many of the metals belonging to the first hazard class form sparingly soluble compounds in a neutral soil environment, and easily soluble compounds in an acidic one. Cadmium is most mobile in an acidic medium and weakly mobile in a neutral and alkaline medium. Mobile in an acidic environment include chemical compounds containing cations Zn, Сu, Pb, Cd, Sr, Mn, Ni, Co, etc. Mobile in a neutral and alkaline environment - Mo, Cr, As, V, Se.
Under equal conditions, phosphates and sulfides of heavy metals have the least solubility; among carbonate compounds, compounds of mercury, lead and cadmium have the lowest solubility. Heavy metal hydroxides form sparingly soluble forms in slightly acidic and neutral media, with the exception of Fe (рН = 2.5) and Al (рН = 4.1) hydroxides.
The mobility is influenced by organic substances with a low molecular weight, fulvic acids and humic acids, so the amount of mobile copper changes from 4.5 mg / kg to 2.0 mg / kg with a change in the humus content in the soil from 0.6 to 6.5% . When the humus content in soil changes from 2.5% to 7.0%, lead adsorption by soil increases from 5 µg/kg to 20 µg/kg.
The introduction of liquid manure and weakly decomposed organic substances into the soil increases the mobility of heavy metals due to the formation of low-molecular water-soluble complexes. The intake of heavy metals in plants according to the degree of their mobility: cadmium - lead - zinc - copper.
To regulate the mobility of heavy metal compounds in the soil, liming, gypsum, organic and mineral fertilizers, earthing (clay or sand) are used.
When recultivating lands contaminated with heavy metals, considerable attention is paid to the maintenance and formation of sparingly soluble compounds in the soil. For this, in addition to the above methods, artificial and natural adsorbents are used. Peat, moss, chernozem soils, sapropel, bentonite and bentonite-like clays, glauconite sands, clinoptilolites, flasks, tripoli, diatomites belong to the natural ones. Artificial adsorbents are created as a result of activation or mixing of natural adsorbents, for example, activated carbon, aluminosilicate and iron-aluminosilicate adsorbents, coal-aluminum gels, SORBEKS adsorbent, ion-exchange resins, polystyrene.
The selective ability of adsorbents can be focused on certain metals, for example, when using the adsorbent "MERCAPTO-8-TRIAZIN", cadmium, lead, mercury and nickel pass into compounds inaccessible to plants (the experience of Japan, France, Germany and other countries), the use of clinoptololite is significantly reduces the intake of lead, chromium, cadmium, copper, zinc in plants, etc.
4) Regulation of the ratio of chemical elements in the soil. This method is based on the antagonism and synergy of chemical elements, i.e. when one element prevents or facilitates the entry of another into the plant, for example, zinc prevents the entry of mercury, and an excess of phosphorus leads to a decrease in the toxicity of zinc, cadmium, lead and copper, the presence of calcium can create antagonistic conditions for some metals, and synergistic conditions for others, in a fertile In soil, zinc and cadmium resist the fixation of copper and lead, and in poor soil, the process can develop in the opposite direction.
5) Creation of a reclamation layer, replacement or dilution of a contaminated soil layer can be carried out according to a multilayer scheme, as well as by applying one layer of soil to a previously screened or unscreened contaminated surface. Dilution of the contaminated layer is carried out by earthing clean soil, followed by mixing, dilution can also be carried out by deep plowing, when the upper contaminated layer is mixed with the clean lower layer. They use the removal of a contaminated layer and its processing, or the removal of contaminated soil, followed by cleaning and returning back, but usually such operations are carried out in small areas, they are an expensive method of reclamation.
For the reclamation of large areas, including residential and recreational areas of settlements, agricultural land experiencing long-term pollution, the following complex scheme can be applied:
- significant reduction of emissions by enterprises (technological barrier);
- strict dosing of chemical plant protection products, optimal regulation of the nutrient and acid regimes of the soil (technological barrier);
- management of water migration flows through the organization of surface runoff, the creation of storm sewers, drainage, followed by wastewater treatment (mechanical barrier).
- strengthening the sorption barrier of the soil layer, which is necessary to significantly reduce the amount of mobile compounds of heavy metals that enter plants and pollute products, while the total amount of metals in the soil can not only not decrease, but even increase due to a decrease in mobility.
- in addition to this - minimization of the infiltration component of the water regime of the soil layer in the conditions of irrigation of green spaces, lawns, garden, agricultural and other crops, i.e. implementation of measures aimed, on the one hand, at some weakening of the hydrophysical barrier, but on the other hand, necessary to consolidate the effect of strengthening the sorption barrier.
A decrease in the number of mobile compounds during the introduction of a sorbent actually weakens the redistribution of the total content of metals along the soil profile under the action of downward moisture currents and leads to excessive accumulation of metals in the uppermost layer. The weakening of the hydrophysical barrier by controlled infiltration contributes to the redistribution of metals, since the soil solution is diluted and the hardly soluble compounds are simultaneously reduced due to desorption.
Such an event can be considered possible, since with significant contamination of soils and groundwater with toxic substances, it is necessary to create an engineering and environmental permanent system for controlling the flow of matter in the components: soil - groundwater. Such a system ensures the reclamation of polluted soils and groundwater, and also serves as a barrier to the flow of technogenic products into rivers and other places of groundwater discharge. For the quantitative substantiation of these measures, mathematical models of the movement of moisture, as well as heavy metals, are used, taking into account their sorption and selection by plant roots.
Conclusion
The relevance of the problem of the impact of heavy metals on soil microorganisms is determined by the fact that it is in the soil that most of all the processes of mineralization of organic residues are concentrated, which ensure the conjugation of the biological and geological cycles. The soil is the ecological node of the biosphere, in which the interaction of living and non-living matter proceeds most intensively. On the soil, the processes of metabolism between the earth's crust, hydrosphere, atmosphere, and land-dwelling organisms are closed, an important place among which is occupied by soil microorganisms.
Increasing environmental pollution with heavy metals (TM) poses a threat to natural biocomplexes and agrocenoses. The TMs accumulated in the soil are extracted from it by plants and enter the body of animals through trophic chains in increasing concentrations. Plants accumulate TM not only from the soil, but also from the air. Depending on the type of plants and the ecological situation, they are dominated by the influence of soil or air pollution. Therefore, the concentration of TM in plants may exceed or be below their content in the soil. Especially a lot of lead from the air (up to 95%) is absorbed by leafy vegetables.
In roadside areas, vehicles significantly pollute the soil with heavy metals, especially lead. At its concentration in the soil of 50 mg/kg, about a tenth of this amount is accumulated by herbaceous plants. Also, plants actively absorb zinc, the amount of which in them can be several times higher than its content in the soil.
Heavy metals significantly affect the abundance, species composition, and vital activity of soil microbiota. They inhibit the processes of mineralization and synthesis of various substances in soils, suppress the respiration of soil microorganisms, cause a microbostatic effect, and can act as a mutagenic factor.
Bibliography
1. Harmful chemicals: inorganic compounds of elements of groups I-IV / ed. V.A. Filov. - L.: Chemistry, 2008. - 611 p.
2. Dzhuvelikyan Kh. A., Shcheglov D. I., Gorubnova N. S. Pollution of soils with heavy metals. Ways to control and standardize polluted soils. Voronezh: Publishing and Printing Center of Voronezh State University, 2009. - 21 p.
3. GN 2.1.7.020-94. Tentative Permissible Concentrations (APC) of heavy metals and arsenic in soils. Supplement No. 1 to the list of MPC and AEC No. 6229-91. - M.: Goskomsanizdat, 1995.
4. GOST 17.4.2.03-86 (ST SEV 5299-85). Protection of Nature. Soils. Soil passport. - M.: Goskomsanizdat, 1987.
5. GOST 17.4.3.01-83 (ST SEV 3847-82). Protection of Nature. Soils. General requirements for sampling. - M.: Goskomsanizdat, 1984.
6. GOST 17.4.3.06-86 (ST SEV 5301-85). Protection of Nature. Soils. General requirements for the classification of soils according to the influence of chemical pollutants on them. - M.: Goskomsanizdat, 1987.
7. Guidelines for the determination of heavy metals in agricultural soils and crop production. - M. : TsINAO, 1992. - 60 p.
8. Motuzova G.V. Ecological monitoring of soils / G.V. Motuzova, O.S. Bezuglov. - M.: Academic Project; Gaudeamus, 2007. - 237 p.
9. Perelman A.I. Landscape geochemistry / A.I. Perelman, N.S. Kasimov. - M. : Astreya-2000, 1999. - 768 p.
10. Reimers N.F. Nature management: words.-ref. / N.F. Reimers. - M. : Thought, 1990. - 638 p.
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What are the causes of soil pollution?

To the urgent question of what causes soil contamination with heavy metals, environmentalists answer: there are several main reasons. Most strongly on soil pollution and degradation, the deterioration of its quality affects:

1. The development of the industrial activity of mankind. Despite the fact that the progression of the industrial sector has made it possible for mankind to make a big breakthrough in development, this sphere has been and remains dangerous for the ecology and health of the planet. This is due to the fact that the mass extraction of minerals, rocks, the creation of mines and mines contribute to the fact that a large amount of industrial waste remains on the soil surface, which does not decay and is not processed for many years. Soil is contaminated with oil and oil products. The soil becomes unsuitable for further use.
2. Development of the agricultural sector. In the process of development of the agricultural sector, an increasing number of fertilizers and methods of processing cultivated crops ceased to have a natural basis and became chemical. The use of chemically active substances simplifies and improves the process of production of agricultural products, increases the yield. However, these same chemicals become dangerous and harmful to the soil and humanity. How does soil pollution affect human health? Foreign substances do not decompose and do not break down in the soil, seep into the water, poisoning and gradually reducing the fertility and health of the soil. Chemicals in agriculture also poison plants, cause soil pollution and depletion, and become a serious threat to the planet's atmosphere.
3. Waste and their disposal. Despite the fact that the industrial sphere of human activity annually causes a huge blow to the ecology and cleanliness of the soil with its waste, man himself pollutes the planet no less. Currently, the main indicators of soil pollution with chemicals are natural human waste, which accumulates in the form of huge piles of biological debris. Human waste contains a large amount of toxic substances that adversely affect the health and functioning of the soil.
4. Oil accidents. In the process of production and transportation of petroleum products, a considerable amount of them can be spilled or scattered on the soil. There are more than enough examples of this phenomenon during the oil production. Oil seeps into the ground and enters the groundwater, which impregnates the soil and provokes soil pollution with oil products, making it unsuitable for further use, and water dangerous to human health.
5. Acid rain and its consequences. Acid rain is the result of human industrial activity. Evaporation of large amounts of chemicals into the atmosphere causes them to accumulate and seep back into the ground as rain. Chemical rain can significantly damage plants and soil, alter their biological structure and make them unsuitable for further use or consumption.

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What will soil pollution lead to?

Contamination of the soil with radioactive substances and other dangerous elements is directly related to the health and well-being of mankind, since we obtain everything important for the functioning and life of substances from the soil and what grows on it. Therefore, the consequences of soil pollution affect many areas of human life.

Pollution of the soil with pesticides worsens the health and well-being of a person. Food, consisting of poisoned plants or unhealthy animal meat, sooner or later leads to the formation of new diseases, mutations, deterioration of body functions as a whole. Soil contamination with pesticides is especially dangerous for the younger generation, because the less healthy food a child receives, the weaker the new generation will be.

Soil pollution is dangerous for the development of chronic and genetic diseases. The impact of soil pollution on human health lies in the fact that chemicals in the composition of plants or animal products can cause the development in the human body of new chronic ailments or congenital diseases that cannot be cured by known methods and medicines. In addition, plants and animal meat poisoned by chemicals can lead to starvation and food poisoning that cannot be stopped for a long time.

Contaminated soil leads to mutations and destruction of plants. Chemicals in the soil cause plants to stop growing and fruiting because they do not have the ability to adapt to changes in the chemical composition of the soil. As a result of radioactive contamination of the soil, a significant number of crops can disappear, and the accumulation and mutation of some plants can lead to soil erosion, changes in soil composition and global poisoning.

Poisoned soil is the cause of toxic substances in the air. Many types of soil pollution and waste products that accumulate on the soil surface lead to the formation of toxic fumes and gases. How does soil pollution affect humans? Toxic substances in the air enter the lungs of a person and can provoke the development of allergic reactions, many chronic diseases, diseases of the mucous membrane, and oncological problems.

Soil pollution disrupts the biological balance and soil structure. What causes soil pollution? Soil pollution leads to the gradual extermination of earthworms and many types of insects that maintain the balance of flora and promote soil renewal. Without these types of living beings, the soil can change its structure and become unsuitable for its further use.

How to solve the problem of soil pollution?

If the problem of waste and waste disposal can be dealt with by building recycling plants, then other causes of pollution are difficult to eliminate quickly and easily.

Before embarking on solving the problem of soil pollution, it is worthwhile to study in detail the scale and severity of pollution, indicators of soil pollution, as well as to understand the causes of this phenomenon in a particular area or area.

Chemical contamination of the soil can occur under the influence of several factors that should be considered:

Quantity and intensity of contaminants and waste entering the soil.
General characteristics of the soil that is being polluted (soil absorption parameters, soil structure, soil moisture and solubility levels, friability, etc.).
Peculiarities of climate and weather conditions in the selected zone or area of pollution.
Structure and state of factors that can spread pollution (presence and amount of groundwater, amount of green spaces, species of animals living in the selected area).
Features of biological factors that affect the breakdown of chemicals, their absorption or disinfection in the soil, hydrolysis processes.

The EcoTextEspress laboratory provides modern services for scanning and biological analysis of the soil, checking the chemical composition of the soil and its morphological characteristics. Based on the results of the analysis, highly qualified personnel will provide a complete package of documents with data on the condition of the tested soil, its saturation with minerals and suitability for further use.

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ENVIRONMENTAL ASSESSMENT OF SOIL POLLUTION WITH HEAVY METALS

UDC 631.45.

Snetilova Valeria Sergeevna,
Vologda State University

Master student of the Department of Geoecology and Engineering Geology, Faculty of Ecology

ENVIRONMENTAL ASSESSMENT OF SOIL POLLUTION WITH HEAVY METALS

Shatilova Valeria,

undergraduate of 2 years of training

Department of Geoecology and engineering Geology, faculty of ecology

Vologda State University

ANNOTATION:

The soil is the most important element of the ecosystem, it includes various polluting components of chemical origin, such as heavy metals, which bind to the organic and mineral environment of the soil, increasing its toxicity. The excess of heavy metals in the soil cover has a negative impact on the agricultural products grown, the phytosanitary indicators of plants, which, in turn, is an important marker of the ecological quality of crop production of the agro-industrial complex of the country. The studies covered arable soddy-podzolic soils of the Vologda Oblast, which are subject to intense anthropogenic impact.

ABSTRACT:

The soil is the most important element of the ecosystem, includes the different polluting components of chemical origin, such as heavy metals, bind with organic and mineral soil pH, increasing indicators of toxicity. High concentrations of heavy metals in soil negatively affects grown agricultural products, phytosanitary indica plants, which, in turn, is an important marker of ecological quality of crop products agro-industrial complex of the country. The researches covered arable sod-podzolic soil of the Vologda area exposed to intensive anthropogenic impact.

Keywords: soil, heavy metals, toxicity, phytosanitary state of plants, ecological quality of plant products.

key words: soil, heavy metals, toxicity, phytosanitary condition of plants, ecological quality of vegetable production.

The fight against pollution of various natural environments is the most important task of Russia's environmental security.

There are many studies in the direction of studying the nature of ecosystem pollution, covering various individual aspects of water, soil, and air pollution.

The soil is the most important element of biogeocenosis, it includes various polluting components of chemical origin, such as heavy metals that bind to the organic and mineral environment of the soil, increasing its toxicity. The excess of heavy metals in the soil cover negatively affects the agricultural products grown, the phytosanitary indicators of plants, which, in turn, is an important marker of the ecological quality of crop products of the country's agro-industrial complex.

The aim of our research isassessment of heavy metal pollution of arable soddy-podzolic soils in the Vologda region.

To achieve the goal, it is necessary to decide tasks :

1. Analysis of soil types and soil formation factors;

3. Analysis of the influence of heavy metals on the vital activity of plant organisms.

A fairly diverse soil cover has formed on the territory of the Vologda Oblast. Most of the agricultural land is located on soils of the soddy-podzolic type.

The studies covered arable soddy-podzolic soils of the Vologda Oblast, which are subject to intense anthropogenic impact. MPCs are determined using hygienic standards.

In loamy soils MPC for copper is exceeded.

Copper is an integral element of the complex of oxidative enzymes. Copper has a positive effect on the processes of photosynthesis, chlorophyll, synthesis processes in plant organisms.

In loamy and sandy soils, the MPC is exceeded for zinc content. In sandy soils MPC is not exceeded.

Zinc takes an active part in redox reactions, respiratory processes, the transformation of various compounds, is important for phosphorus and carbohydrate metabolism, the synthesis of nucleic acids and proteins, starch, and controls the fruiting process. With a lack of zinc, the activity of enzymes decreases, various diseases of the leaf blade appear.

In loamy soils, an excess of MPC for manganese content is observed. In sandy and sandy soils, MPC is not exceeded.

Manganese takes part in photosynthetic and respiratory processes, is a regulator of redox reactions in plants. With nitrogen nutrition, manganese acts as a reducing agent, with ammonia nutrition it serves as a strong oxidizing agent. Manganese is located mainly in chloroplasts, accelerates nitrogen fixation, increases the amino acid series, boosts the fermentation of alcohols and aerobic oxidation of carbohydrates, and leads to the activation of enzymes that catalyze redox reactions.

In the examined soil samples, the MPC for cobalt was not exceeded.

The physiological significance of cobalt for plant life is very large and varied. Cobalt increases the yield of potato crops, as well as the content of starch compounds in it. It enhances the process of protein biosynthesis, increases the content of ascorbic acids, accelerates the flowering process of clover culture and leads to an increase in the yield of many vegetable crops.

In the examined soil samples, the MPC for cadmium was not exceeded.

Cadmium is a very toxic metal. Cadmium is actively absorbed by plants, but they do not need them for normal life. Cadmium stagnation occurs in the root systems, to a lesser extent in the stem and leaves. With the help of chlorophyll, cadmium is concentrated in plant tissues. With an increase in the content of cadmium in plants, chlorosis of the leaf blades occurs, the leaves acquire a red-brown color along the edges and veins, in addition, inhibition of growth processes and damage to the roots of plants is observed.

In loamy and sandy soils, an excess of MPC is observed for the average content of lead, in sandy soils, MPC is not exceeded.

Lead in small amounts (from 5 to 10 mg/kg) increases the starch content, accelerates the process of germination of plant seedlings.

In loamy soils, an excess of MPC is observed in terms of nickel content. In sandy and sandy soils, MPC is not exceeded.

The biological significance of nickel is currently not well understood, but it is found in various plant organisms. Nickel affects the yield of agricultural crops.

In loamy soils, an excess of MPC is observed for the average content of chromium. In sandy and sandy soils, MPC is not exceeded.

Chromium is needed by plants in small doses, but its physiological significance is poorly understood.

In all the studied soils, MPC is exceeded. The greatest excess is in soddy-podzolic loamy soils.

In soils where there is an excess of MPC, it is necessary to carry out phytosanitary measures, consisting in overseeding grass stands (within crop rotations), accumulating heavy metals from the soil.

BIBLIOGRAPHY:

Ukhanov V.P. , Khamitova S.M. , Avdeev Yu.M. Ecological monitoring of the state of specially protected natural areas//. 2016. No. 10 (121). pp. 66-71.

Ruvinova L.G. , Sverchkova A.N. , Khamitova S.M. , Avdeev Yu.M. Biological monitoring of soil and water pollution in urbanization // Bulletin of the Krasnoyarsk State Agrarian University. 2016. No. 6 (117). pp. 14-20.

Akhmedov A.E., Akhmedova O.I., Shatalov M.A. Formation of a waste management system in the Russian Federation // Problems of reclamation of household waste, industrial and agricultural production. IV International Scientific Ecological Conference (with the participation of ecologists from Azerbaijan, Armenia, Belarus, Germany, Georgia, Kazakhstan, Kyrgyzstan, Latvia, Lebanon, Moldova, Transnistria, Russia, Slovakia, Uzbekistan and Ukraine). Krasnodar, 2015. S. 718-721.

Korchagov S.A., Avdeev Yu.M., Khamitova S.M., Glinina Yu.V., Enalsky A.P. Ecological and genetiScientific assessment of the properties of spruce trees of various ecotypes in the conditions of the Vologda Oblast//Bulletin of the Krasnoyarsk State Agrarian University. 2016. No. 5 (116) . pp. 65-72

Avdeev Y.M. The influence of the crown on the formation of the tree //
Ural Scientific Bulletin. 2016. Vol. 11. № 2 . pp. 129-130

Avdeev Y.M. The environmental performance of wood in forest ecosystems// Ural Scientific Bulletin. 2016. Vol. 11. № 2 . pp. 131-132

Bely A.V., Zavarin D.A., Protopopova E.V. Methodology for training bachelors of land management at VoGTU in the light of the introduction of new generation geodetic instruments//In the collection: University science - to the region Materials of the Tenth All-Russian Scientific and Technical Conference in 2 volumes. Managing editor: Plekhanov A.A. Vologda, 2012. P. 190-192

Tesalovsky A.A. // Proceedings of the St. Petersburg State Agrarian University. 2011. No. 23. pp. 337-341

Bely A.V., Krutov G.G., Protopopova E.V. Optimization of the training of bachelors-land surveyors and ways to achieve it//In the collection: University science - to the region Materials of the XII All-Russian Scientific and Technical Conference. 2014. S. 368-370

Tesalovsky A.A. Methodology for the cadastral valuation of lands reserved for the construction of reservoirs for complex purposes //
Bulletin of MGSU. 2010. No. 2. pp. 31-36

Shatalov M.A., Mychka S.Yu. The mechanism of household waste management within the framework of the system of environmentally friendly recycling technologies // Economics. Innovation. Quality control. 2015. No. 3 (12). S. 181.

Popov Yu.P., Bely A.V. Features of the development of a territorial waste management scheme based on a regional GIS//University science - to the region materials of the XIV All-Russian scientific conference. 2016. S. 117-119

Bely A.V., Popov Yu.P. On the issue of environmental pollution in the handling of municipal solid waste// NovaUm.Ru. 2017. No. 5. pp. 186-188

Bely A.V., Popov Yu.P. Results of a comprehensive study of environmental pollution from MSW landfills in rural settlements of the Vologda Oblast//In the collection: University science - to the region Materials of the Tenth All-Russian Scientific and Technical Conference in 2 volumes. Managing editor: Plekhanov A.A. Vologda, 2012. P. 192-195

Popov Yu.P., Bely A.V. Management of the system for handling land used for the disposal of solid household waste in the Vologda Oblast based on a geographic information system//Ecology of industrial production. 2012. No. 3. pp. 80-84

Popov Yu.P., Bely A.V. Features of managing the choice of sites for the construction of landfills for municipal solid waste//In the collection: University science - to the region Materials of the XII All-Russian Scientific and Technical Conference. 2014. S. 245-247

Asaul A.N., Asaul M.A., Zavarin D.A. Features of state cadastral registration of a land plot // Tauride scientific observer. 2015. No. 5-1. pp. 107-115

Asaul A.N., Zavarin D.A., Ivanov S.N.Organizational mechanismsof stimulating innovative activity of regional investment constructionclusters// Bulletin of civil engineers. 2015. № 5 (52) . pp. 273-282

Bely A.V., Popov Yu.P. To the question of substantiation of the system of solid domestic waste management on the basis of municipal GIS //
In the collection: University science - to the region Materials of the Seventh All-Russian Scientific and Technical Conference in 2 volumes. Vologda, 2009. S. 252-254

Tesalovsky A.A. Features of cadastral support for the development of a scheme for the placement of waste processing and storage facilities when planning the development of territories//Eurasian Law Journal. 2017. No. 1 (104) . pp. 371-374

Popov Yu.P., Bely A.V. Management of the system of handling land used for the disposal of municipal solid waste in the Vologda region based on GIS // Land management, cadastre and land monitoring. 2012. No. 9 (93) . pp. 56-61

Bely A.V., Popov Yu.P. О Possibilities of ecological substantiation of territorial construction standards for the treatment of municipal solid waste at the regional level// In the collection: University science - to the region Materials of the ninth all-Russian scientific and technical conference in 2 volumes. Vologda, 2011. S. 203-206

Khamitova S.M., Avdeev Yu.M., Selishcheva O.A. Research of soil microflora of the arboretum named after Nikolai Klyuev// In the collection: 2015. P. 78

Khamitova S.M., Avdeev Yu.M. Microbiological studies of soils in green urban plantings of the Vologda region//Bulletin of the Krasnoyarsk State Agrarian University. 2016. No. 10 (121) . pp. 29-35

Rudakov V.O., Kartabaeva B.B., Khamitova S.M., Avdeev Yu.M. Microorganisms of the soil of the arboretum of Nikolai Klyuev// Biotics. 2015. Vol. 7. No. 6. pp. 172-175

Study of soil microflora in forest nurseries of the Vologda region//Samara Scientific Bulletin. 2016. No. 3 (16) . pp. 53-56

Zaidelman F.R., Plavinsky V.A., Bely A.V. Influence of deep reclamation loosening on the physical properties of soils on heavy cover rocks and yield // Bulletin of Moscow University. Episode 17: Soil Science. 1986. No. 2. pp. 10-16

Khamitova S.M., Avdeev Yu.M., Snetilova V.S. Study of pathogenic rhizospheric nematode fauna of the Nikolay Klyuev Arboretum// In the collection: Actual problems of development of the forest complex materials of the International scientific and technical conference. 2017. S. 49-52

Khamitova S.M., Avdeev Yu.M., Konashenko Yu.I., Klimovskaya A.R., Selyakova N.S., Snetilova V.S. Studies of soil microflora in the cedar grove of Gryazovets in the Vologda region// In the collection: Collection of materials of the III Youth Ecological Forum 2015. P. 80

Duryagina N.V., Andreeva T.V., Khamitova S.M., Avdeev Yu.M. Organization and state of phytosanitary control in the Vologda region// In the collection: Sprouts of Science Collection of scientific works of students, graduate students and young scientists, dedicated to the 70th anniversary of the Faculty of Agronomy and Forestry. 2013. S. 17-18

Avdeev Yu.M. Energy assessment of agroecosystems//NovaUm.Ru . 2017. No. 6. pp. 47-51

Shatalov M.A., Mychka S.Yu. Formation of a system for deep processing of waste products of food production in the agro-industrial complex // Problems of reclamation of household waste, industrial and agricultural production. IV International Scientific Ecological Conference (with the participation of ecologists from Azerbaijan, Armenia, Belarus, Germany, Georgia, Kazakhstan, Kyrgyzstan, Latvia, Lebanon, Moldova, Transnistria, Russia, Slovakia, Uzbekistan and Ukraine). 2015. S. 402-404.

Filippova A.B., Avdeev Yu.M. Formation of shoots and resistance of perennial grasses in sown grass stands of the Far North//Bulletin of the Krasnoyarsk State Agrarian University. 2015. No. 7. pp. 130-134

Mychka S.Yu., Shatalov M.A. Formation of a system for deep processing of industrial and industrial waste subsystems of the agro-industrial complex // Agrotechnics and energy supply. 2015. No. 3 (7). pp. 185-190.

Avdeev Yu.M., Kostin A.E., Litonina A.S. Influence of vegetable feed additives on dry matter digestibility and protein digestibility in barley grain stored under sealed conditions //
Feed production. 2011. No. 7. pp. 37-38

Zorin D.P., Starkovsky B.N., Avdeev Yu.M., Kostin A.E. The effectiveness of the use of insecticides on seed plantings of fireweed angustifolia //
Feed production. 2012. No. 1. pp. 28-29

Bautin V.M., Shatalov M.A. Directions for the development of a system for deep processing of industrial waste subsystems of the agro-industrial complex // Economics. Innovation. Quality control. 2015. No. 3 (12). pp. 72-73.

Avdeev Yu.M., Kostin A.E. Vegetable Feed Additives: Impact on Grain in Sealed Conditions // Feed production. 2011. No. 8. pp. 33-34

Hygienic standards GN 2.1.7.2511-09. Approximately permissible concentrations of chemicals in the soil [Electronic resource]. - Approved. Decree of the Chief State Sanitary Doctor of the Russian Federation dated May 18, 2009 No. No. 32 // Portal of regulatory documents. – Access mode: hptt: // OpenGost.ru.

Soil pollution with heavy metals has different sources:

1. waste from the metalworking industry;

2. industrial emissions;

3. products of fuel combustion;

4. automotive exhaust gases;

5. means of chemicalization of agriculture.

Metallurgical enterprises annually emit more than 150 thousand tons of copper, 120 thousand tons of zinc, about 90 thousand tons of lead, 12 thousand tons of nickel, 1.5 thousand tons of molybdenum, about 800 tons of cobalt and about 30 tons of mercury to the surface of the earth . For 1 gram of blister copper, waste from the copper smelting industry contains 2.09 tons of dust, which contains up to 15% copper, 60% iron oxide and 4% each of arsenic, mercury, zinc and lead. Wastes from engineering and chemical industries contain up to 1 g/kg of lead, up to 3 g/kg of copper, up to 10 g/kg of chromium and iron, up to 100 g/kg of phosphorus, and up to 10 g/kg of manganese and nickel. In Silesia, dumps with a zinc content of 2 to 12% and lead from 0.5 to 3% are heaped around zinc plants, and ores with a zinc content of 1.8% are exploited in the USA.

With exhaust gases, more than 250 thousand tons of lead per year enters the soil surface; it is the main soil pollutant with lead. Heavy metals enter the soil along with fertilizers, in which they are included as an impurity.

Although heavy metals are sometimes found in soils in low concentrations, they form stable complexes with organic compounds and enter into specific adsorption reactions more easily than alkali and alkaline earth metals. Near enterprises, natural phytocenoses of enterprises become more uniform in species composition, since many species cannot withstand increasing the concentration of heavy metals in the soil. The number of species can be reduced to 2-3, and sometimes to the formation of monocenoses. In forest phytocenoses, lichens and mosses are the first to react to pollution. The tree layer is the most stable. However, long-term or high-intensity exposure causes dry-resistant phenomena in it. Restoration of disturbed soil cover requires a long time and large investments.

A particularly difficult task is the restoration of vegetation cover on overburden dumps and tailings (tailings) of workings where metal ores were mined: such tailings are usually poor in nutrients, rich in toxic metals and poorly retain water. A serious problem for the environment is wind erosion of mine dumps.

Rationing of the content of heavy metals in the soil

Rationing the content of heavy metals in soil and plants is extremely difficult due to the impossibility of fully taking into account all environmental factors. So, changing only the agrochemical properties of the soil (reaction of the environment, humus content, degree of saturation with bases, granulometric composition) can reduce or increase the content of heavy metals in plants several times. There are conflicting data even on the background content of some metals. The results given by researchers sometimes differ by 5-10 times.

Numerous scales of environmental regulation of heavy metals have been proposed. In some cases, the highest content of metals observed in ordinary anthropogenic soils is taken as the maximum allowable concentration, in others - the content that is the limit in terms of phytotoxicity. In most cases, MPCs have been proposed for heavy metals, which exceed the actual allowable values of metal concentrations by several times.

To characterize technogenic pollution with heavy metals, a concentration coefficient is used that is equal to the ratio of the concentration of an element in contaminated soil to its background concentration.

Table 1 shows officially approved MPCs and permissible levels of their content in terms of harmfulness. In accordance with the scheme adopted by medical hygienists, the regulation of heavy metals in soils is divided into translocation (transition of an element into plants), migratory water (transition into water), and general sanitary (influence on the self-cleaning capacity of soils and soil microbiocenosis).

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