Guidelines for assessing the degree of danger of soil contamination by chemicals. Assessment of chemical indicators of soil pollution Comprehensive indicator of soil pollution formula

Assessment of the actual state is a key area within the framework of environmental monitoring. She allows you to determine trends in changes in the state of the environment; degree of ill-being and its causes; helps make decisions to normalize the situation. Can be favorable situations have been identified, indicating the presence of ecological reserves of nature.

Ecological reserve of natural ecosystem There is the difference between the maximum permissible and actual state of the ecosystem.

The method for analyzing observation results and assessing the state of the ecosystem depends on the type of monitoring. Typically, the assessment is carried out using a set of indicators or conditional indices developed for the atmosphere, hydrosphere, and lithosphere. Unfortunately, there are no unified criteria even for identical elements of the natural environment. As an example, we will consider only individual criteria.

IN sanitary and hygienic monitoring usually used:

1) comprehensive assessments of the sanitary condition of natural objects based on a set of measured indicators(Table 1) or 2) pollution indices.

Table 1.

Comprehensive assessment of the sanitary condition of water bodies in total physical, chemical and hydrobiological indicators

General principle for calculating pollution indices the following: first, the degree of deviation of the concentration of each pollutant from its maximum permissible concentration is determined, and then the resulting values ​​are combined into a total indicator that takes into account the effects of several substances.

Let us give examples of calculating pollution indices used to assess atmospheric air pollution (AP) and surface water quality (WQ).

Calculation of the atmospheric pollution index air(ISA).

In practical work, a large number of different ISAs are used. Some of them are based on indirect indicators of air pollution, for example, atmospheric visibility, transparency coefficient.

Various ISAs, which can be divided into 2 main groups:

1.Single indices of air pollution by one impurity.

2.Comprehensive indicators of air pollution from several substances.

TO unit indices relate:

Coefficient for expressing the concentration of an impurity in MPC units (a), i.e. the value of the maximum or average concentration, reduced to the maximum permissible concentration:

a = Cί / MPCί

This ISA used as a criterion for atmospheric air quality by individual impurities.

Frequency (g) of impurity concentrations in the air above a given level at a post or at K posts in a city per year. This percentage (%) of cases where single values ​​of impurity concentration exceed a given level:

g = (m/n) ּ100%

Where n- number of observations for the period under consideration, m- number of cases of exceeding one-time concentrations at the post.

ISA (I) as a separate impurity- quantitative characteristic of the level of atmospheric pollution by a separate impurity, taking into account the hazard class of the substance through standardization for the danger of SO 2:

I = (Cg /PDKss) Ki

Where I- impurity, Ki- constant for various hazard classes in reducing the degree of harmfulness of sulfur dioxide, Cg- average annual concentration of impurities.

For substances of different hazard classes Ki is accepted:

The calculation of the API is based on the assumption that at the MPC level, all harmful substances are characterized by the same effect on humans, and with a further increase in concentration, the degree of their harmfulness increases at different rates, which depends on the hazard class of the substance.

This API is used to characterize the contribution of individual impurities to the overall level of air pollution over a given period of time in a given area and to compare the degree of air pollution by various substances.

TO complex indexes relate:

Comprehensive Urban Air Pollution Index (CIPA) is a quantitative characteristic of the level of air pollution created by n substances present in the city’s atmosphere:

KIZA=

Where II- unit index of atmospheric pollution by the i-th substance.

The comprehensive index of air pollution by priority substances is a quantitative characteristic of the level of air pollution by priority substances that determine air pollution in cities, calculated similarly to KIZA.

Calculations of the natural pollution index water(WPI) can also be performed using several methods.

Let us give as an example the calculation method recommended by the regulatory document, which is an integral part of the Rules for the Protection of Surface Waters (1991) - SanPiN 4630-88.

At the beginning measured concentrations of pollutants are grouped according to limiting signs of harmfulness - LPV(organoleptic, toxicological and general sanitary). Then, for the first and second (organoleptic and toxicological DP) groups, calculate degree of deviation (A i) of actual concentrations of substances (C i) from their MPC i, the same as for atmospheric air ( A i = C i /MPC i). Next they find amounts indicators A i, for the first and second groups of substances:

where S is the sum of A i for substances regulated by organoleptic (S org) and toxicological (S tox) LPW; n is the number of summarized water quality indicators.

In addition, to determine WPI, they use the amount of oxygen dissolved in water And BOD 20(general sanitary LP), bacteriological indicator- the number of lactose-positive E. coli (LPKP) in 1 liter of water, smell and taste. The water pollution index is determined in accordance with the hygienic classification of water bodies according to the degree of pollution (Table 2).

By comparing the corresponding indicators (S org, S tox, BOD 20, etc.) with the estimated ones (see Table 2), the pollution index, the degree of pollution of the water body and the water quality class are determined. The pollution index is determined by the most stringent value of the assessment indicator. So, if according to all indicators water belongs to quality class I, but the oxygen content in it is less than 4.0 mg/l (but more than 3.0 mg/l), then the WPI of such water should be taken as 1 and classified as class II quality (moderate degree of contamination).

The types of water use depend on the degree of water pollution of a water body.(Table 3).

Table 2.

Hygienic classification of water bodies by degree of pollution (according to SanPiN 4630-88)

Table 3

Possible types of water use depending on the degree of water pollution object (according to SanPiN4630-88)

Degree of pollution	Possible use of the water body
Acceptable	Suitable for all types of water use by the population with virtually no restrictions
Moderate	Indicates the danger of using a water body for cultural and domestic purposes. Use as a source of household and drinking water supply without reducing the level of chemical contamination at water treatment plants can lead to initial symptoms of intoxication in part of the population, especially in the presence of substances of the 1st and 2nd hazard classes
High	There is an absolute danger of cultural and domestic water use on a water body. It is unacceptable to use it as a source of domestic drinking water supply due to the difficulty of removing toxic substances during the water treatment process. Drinking water can lead to symptoms of intoxication and the development of isolated effects, especially in the presence of substances of hazard classes 1 and 2
Extremely high	Absolutely unsuitable for all types of water use. Even short-term use of water from a water body is dangerous to public health

To assess water quality, the services of the Ministry of Natural Resources of the Russian Federation use the methodology for calculating WPI only based on chemical indicators, but taking into account more stringent fishery MPCs. At the same time, there are not 4, but 7 quality classes:

I - very clean water (WPI = 0.3);

II - pure (WPI = 0.3 - 1.0);

III - moderately polluted (WPI = 1.0 - 2.5);

IV - polluted (WPI = 2.5 - 4.0);

V - dirty (WPI = 4.0 - 6.0);

VI - very dirty (WPI = 6.0 - 10.0);

VII - extremely dirty (WPI more than 10.0).

Assessing the level of chemical contamination soil carried out according to indicators developed in geochemical and geohygienic studies. These indicators are:

· chemical concentration coefficient (K i),

K i = C i / C fi

Where C i– actual content of the analyte in the soil, mg/kg;

With fi– regional background content of the substance in the soil, mg/kg.

If there is a MPC i for the soil type under consideration, K i is determined by multiplicity of exceeding the hygienic standard, i.e. according to the formula

K i = C i / MPC i

· total pollution index Zc, which is determined by sum of chemical substance concentration coefficients:

Zc = ∑ K i – (n-1)

Where n– number of pollutants in the soil, Ki- concentration coefficient.

Approximate estimate soil pollution hazard scale based on total indicator presented in table. 3.

Table 3

Environmental monitoring is of particular importance in the global environmental monitoring system and, first of all, in monitoring renewable resources of the biosphere. It includes monitoring the ecological state of terrestrial, aquatic and marine ecosystems.

As criteria, characterizing changes in the state of natural systems, can be used: balance of production and destruction; value of primary production, structure of biocenosis; rate of nutrient cycling etc. All these criteria are expressed numerically by various chemical and biological indicators. Thus, changes in the Earth's vegetation cover are determined by changes in the area of ​​forests.

Urban soils. As a result of urban planning and economic activities, soils are subject to degradation, alienation, and pollution.

Degradation of urban soils - This is the destruction of the fertile soil layer, partial or complete destruction of the soil cover, accompanied by a deterioration in its physical and biological condition, and a decrease in fertility.

Degradation processes include:

- soil erosion– destruction of soils and removal of loose components of soil material by water and wind. Water erosion occurs under the influence of surface runoff, rain and melt water. Wind erosion (deflation) represents the blowing of fine earth from the upper soil layers.

- Reconsolidation. The city's soils are heavily compacted from the surface, in the root layer. Soil compaction leads to a decrease in their porosity, and therefore to a decrease in soil moisture capacity and air permeability. The movement of water in the soil, water-lifting capacity and mobility of water depend on the size of the pores.

Lands are being alienated for residential buildings, industrial facilities, roads. Built-up or paved lands in large cities occupy up to 70-80% of the urban area. Soils sealed by asphalt and residential and industrial buildings are practically impermeable to precipitation and, to a lesser extent, to air. Sealed soils have changed water, air and thermal regimes. They are characterized by conditions of high humidity, oxygen deficiency, and a smaller temperature gradient.

Soils sealed under buildings become waterlogged without natural aeration. This causes an increase in humidity in basements and leads to the destruction of foundations.

Excessive covering of the soil with asphalt in forest parks, squares, boulevards and other similar areas is also unfavorable: roots that fall under the asphalt die under anaerobic conditions. Part of the soils of the urban area is alienated by littering with household and construction waste. At the same time, landfills become sources of chemical pollution of soils, as well as atmospheric air and groundwater.

Soil pollution As a result of anthropogenic activity, it leads to a change in their chemical composition and deterioration in quality, causing a number of negative consequences, including loss of the ability for bioproductivity and self-purification. Harmful substances enter the soils of cities as a result of the destruction and construction of buildings, emissions from transport, metallurgical, oil refining and chemical plants, power plants, water drainage, and the use of de-icing chemicals.

Indicators and assessment of the ecological state of soils. The main soil pollutants are metals, petroleum products, radioactive substances, fertilizers and pesticides. The main criterion for hygienic assessment of the danger of soil pollution by harmful substances is their maximum permissible concentrations.

According to the level of pollution and the degree of danger to the population, city soils are divided into categories: clean, acceptable, moderately dangerous, dangerous, extremely dangerous. For the “pure” category, the content of chemicals in soils is allowed from background to 1 MPC. For the pollution category “permissible” for hazard classes 1, 2, 3

Organic substances – from 1 MPC to 2 MPC;

Inorganic substances – from 2 background concentrations to 1 MPC

The total pollution indicator Zс is determined as

Zс =Σ Ксi – (n-1), where

N – number of pollutants; Kc – concentration coefficient of a chemical substance is equal to the ratio of the real content of the harmful substance Ci to the background Cf:

Кс = Сi / Сф.

Permissible at Zс less than 16;

Moderately dangerous - at 16... 32;

Dangerous – at 32…128;

Extremely dangerous with a Zc value of more than 128.

Based on the established categories of soil contamination, recommendations are given for their use. Soil category

- “clean” is used without restrictions;

- “permissible” is used without restrictions, excluding high-risk objects;

- “moderately dangerous” is used, and “dangerous” is used to a limited extent during construction work for filling pits and excavations;

- “extremely dangerous” is removed and disposed of at specialized landfills.

Soil protection measures include removal and preservation of the topsoil, anti-erosion measures, and reclamation of contaminated soils.

4.The health-improving function of green spaces in the city environment

- Quality improvement The exchange of air by green spaces occurs due to the release of oxygen and the absorption of carbon dioxide. Poplar produces the greatest amount of oxygen. Green spaces are capable of trapping dust, aerosols and harmful gases. Lilac and elm have the best dust-protective functions; oak and spruce capture less dust. Green spaces absorb heavy metals from the air. The crown of coniferous species adsorbs lead, zinc, cobalt, chromium, copper, and titanium. Lead is absorbed by poplar and maple.

- Noise level is reduced due to the damping of sound vibrations by green spaces. The crowns of deciduous trees absorb up to 26% of the sound energy falling on them.

- Improving the microclimate occurs due to: stabilization of wind conditions by green spaces; increasing air humidity; reducing daily and seasonal humidity fluctuations.

- Reducing surface runoff due to vegetation cover .

- Reduced soil erosion due to the fixation of loose soils by plants.

Standardized indicators of landscaping in the functional planning organization of residential development :

The proportion of green areas for various purposes within the boundaries of a residential area should be at least 25%.

The indicator of provision of residents with green areas is at least 12 sq.m., including public green spaces - at least 6 sq.m./person.

The soil

i Chemical compounds contained in the soil are divided into natural And outsiders .

Substances that are always present in natural soil, but the concentration of which can increase as a result of anthropogenic activity, include, for example, metals - lead, mercury, cadmium, copper, etc. Increased lead content can be caused by absorption from the atmosphere due to vehicle exhaust gases, as a result of the application of fertilizers, pesticides, etc. Arsenic is found in many natural soils at concentrations of approximately 100 ppm, but levels can increase to 500 ppm. Mercury in normal soils ranges from 90 to 250 g/ha; due to grain dressing means, its content can annually increase by 5 g/ha; approximately the same amount enters the soil with rain.

Qualitative and quantitative changes during long-term presence of foreign organic chemicals in the soil and the mechanisms of their redistribution in the soil have not yet been studied for any of these substances.

In the process of transformation of organic substances (Figure 2) in the soil, both abiotic and biotic reactions that occur under the influence of living organisms in the soil, as well as free enzymes, play an important role.

The formation of non-extractable or associated residues of foreign substances in the soil largely determines its quality over a long period of time.

In accordance with the current level of knowledge, the following types of connections are possible in non-extractable xenobiotic residues found in the soil:

¨ inclusion of clay materials in the layered structure;

¨ non-covalent inclusion of humic macromolecules into the voids; the same with the participation of hydrogen bonds, van der Waals forces, interaction with charge transfer;

¨ covalent inclusion due to bonds with monomers and incorporation into the humic macromolecule.

Covalent bonds are most likely for substances with reactive groups similar to the monomers of humic substances, in particular for phenols and aromatic amines.

Bound chemical residues in the soil can be released again through the process of microbiological decomposition and long-term transformation of humic materials and thereby become biologically active in relation to plants. Until they mineralize or participate in carbon metabolism in some way, they are considered extraneous to the environment.

Since soils are often contaminated with several elements at once, they are calculated total pollution indicator Z c, reflecting the effect of a group of elements:

Where K si- concentration coefficient i-th element in the sample; n- number of elements taken into account.

The total pollution indicator can be determined both for all elements in one sample, and for a section of the territory using a geochemical sample.

Assessment of the danger of soil contamination by a complex of elements according to the indicator Z c is carried out according to an assessment scale, the gradations of which were developed based on a study of the health status of the population living in areas with different levels of soil contamination (Table 9).

Table 9 - Indicative rating scale for the danger of soil pollution

Soil pollution categories	Magnitude Z	Changes in population health indicators in pollution hotspots
Acceptable	less than 16	The lowest level of morbidity in children and a minimum of functional deviations
Moderately dangerous	16-32	Increase in overall morbidity rate
Dangerous	32-128	Increase in the overall level of morbidity, the number of frequently ill children, children with chronic diseases, disorders of the functioning of the cardiovascular system
Extremely dangerous	more than 128	Increased morbidity among children, impaired reproductive function of women (increased cases of toxicosis during pregnancy, premature birth, stillbirth, malnutrition of newborns)

One of the main sources of soil pollution is acid rain. For decades, acid pollution affects the buffer capacity of the soil. For many soils, there is a leaching of cations important for plant nutrition, sorption-bound with colloidal soil particles, and as a result they migrate into the deeper layers, becoming inaccessible to plant roots. Therefore, even if the soil pH remains constant, the soil fertility decreases. Continued acidification of the soil can be determined, for example, by a decrease in the concentration of Fe 2+ and Mg 2+ ions, as well as aluminum Al 3+.

Regardless of the release of Al 3+ ions and other cations, including heavy metals, changes in soil pH can lead to other changes. Thus, a decrease in pH prevents the development of microorganisms in the same way as occurs in immature humus soils. Such organisms include, in particular, fungi Mykorrhiza, which promote the absorption of minerals by plant roots. A tangible result of the destruction of soil microorganisms is disruption of its normal respiration. Low pH values ​​promote the addition of anions to iron-containing colloidal particles in the soil, since protons impart a positive charge to the complexes. Phosphates can exchange their acidic residues with OH groups on the surface of colloidal particles, while the phosphate residues bind and further absorption of phosphorus by plants becomes impossible.

Soil acidification has a major effect on many, but not all metals. With an increase in acidity, cadmium, lead and zinc become mobile and are most easily absorbed by plants and animals. Along with soil acidification and an increase in the content of heavy metals and pesticides, soils can contain polychlorinated biphenyls in concentrations of up to 100 mg per 1 kg of dry weight. They disintegrate very slowly in the soil, and for this reason they accumulate in it.

& An example of such contamination is the cultivation of grain crops that are naturally high in selenium. In this case, sulfur in amino acids such as cysteine ​​and methionine is replaced by selenium. The resulting “selenium” amino acids can lead to poisoning of animals and humans. A lack of molybdenum in the soil leads to the accumulation of nitrates in plants; in the presence of natural secondary amines, a sequence of reactions begins that can initiate the development of cancer in warm-blooded organisms.

❐ Thus, anthropogenic chemicals released into the environment - air, water, soil - can be indifferent, undesirable or toxic.

5.2 Classification of alien pollutants - xenobiotics

☞ Foreign substances that enter the human body with food and have high toxicity are called xenobiotics or polluters. These include:

1) metal contaminants (mercury, lead, cadmium, arsenic, tin, zinc, copper, etc.);

I. Sanitary and chemical indicators of the sanitary condition of soils:

The main sanitary and chemical indicator is sanitary number, which indirectly characterizes the process of soil humification and allows one to evaluate the self-cleaning ability of the soil from organic contaminants.

Sanitary number- the quotient of dividing the amount of soil protein nitrogen (humus nitrogen) in mg in 100.0 absolutely dry soil by the total content of organic nitrogen in the same units. The soil is considered clean if the sanitary number approaches 1.

II. Biogeochemical indicators:

The main criterion for the hygienic assessment of soil contamination with chemicals is the maximum permissible concentration (MAC) or approximate permissible concentration (APC) of chemicals in the soil (Table 3).

Chemical concentration factor ( K s) . K s is determined by the ratio of the actual content of the analyte in the soil ( C i)

in mg/kg soil to MPC (Table 3) taking into account the regional background (with MPC):

K c = C i / C maximum

Total pollution indicator ( Z s), which is equal to the sum of the concentration coefficients of chemical pollutant elements and is expressed by the formula: Z c = Σ (K ci + … + K cn) – (n - 1),

Where n- number of determined summable substances;

K si- concentration coefficient of the i-th pollution component.

The assessment of the degree of danger of soil pollution by chemicals is carried out according to the sanitary number, the total indicator of pollution (Table 2).

table 2

Assessment of the degree of chemical contamination of soil

Table 3

Maximum permissible concentrations of exogenous chemicals

Name of substances	MPC, mg/kg	Hazard Class
Metals
Vanadium
Cobalt (mobile form)	5,0
Copper (movable form)	3,0
Nickel	4,0
Mercury	2,1
Lead
Chromium	6,0
Zinc
Inorganic compounds
Nitrates
Arsenic	2,0
Hydrogen sulfide	0,4
Phosphorus (superphosphate)
Fluorides (water soluble form)
Aromatic hydrocarbons
Benzene	0,3
Isopropylbenzene	0,5
Xylenes	0,3
Styrene	0,1
Toluene	0,3
Fertilizers and surfactants (surfactants)
Liquid complex fertilizers with manganese additives
Nitrogen-potassium fertilizers
Surfactant	0,2
Benz(a)pyrene	0,02
DDT	0,05

Assessment of soil sanitary and epidemiological safety indicators

I. Sanitary and bacteriological indicators

1. Indirect, characterize the intensity of the biological load on the soil. These are sanitary indicator organisms of the Escherichia coli group (coli-index) and fecal streptococci (index enterococci).

2. Direct sanitary and bacteriological indicators of the epidemic danger of soil - detection of pathogens of intestinal infections (causative agents

intestinal infections, pathogenic enterobacteria, enteroviruses). The concentration of coliphage in the soil at a level of 10 CFU/g or more indicates infection of the soil with enteroviruses.

The number of geohelminth eggs (roundworms, whipworms, toxocara, hookworms, etc.), biohelminth eggs (opisthorchides, diphyllobothriids, etc.), as well as cysts of intestinal pathogenic protozoa (cryptosporidium, isosporus, lamblia, balantidium, dysenteric amoeba).

II.Sanitary and entomological indicators

The presence of synanthropic flies and their larvae is a direct indicator of soil contamination and allows us to judge the contamination of the soil with certain types of waste and the unsatisfactory state of cleaning in general or certain stages of it (Table 4). In populated areas in public and private households, food and trade enterprises, public catering establishments, zoos, places where service and sport animals are kept), meat and dairy plants, etc. The most likely breeding sites for flies are accumulations of decaying organic matter and soil around them at a distance of up to 1 m.

Table 4

Assessment of the degree of epidemic danger of soil

Soil pollution category	TMC, g	Coliform index	Anaerobe titer, g	Pathogen. bacteria	Geo-helminth eggs, ind./kg	Larvae/pupae of flies in soil with S20×20 cm
Clean	Less than 1000	1 - 10	≥ 0,1
Moderately dangerous	Tens of thousands	10 - 100	0,1-0,001		to 10	up to 10/0
Dangerous	Hundreds of thousands	100 - 1000	0,001-0,0001		up to 100	up to 100/10
Extremely dangerous	Millions	1000 and above	< 0,0001		> 100	> 100 / > 10

Healthy soil is easily permeable, coarse-grained, unpolluted soil if the content of clay and sand in it is 1:3, there are no pathogens or helminth eggs, and microelements are contained in quantities that do not cause endemic diseases.

The results of soil surveys are taken into account when developing measures for their reclamation, prevention of infectious and non-infectious diseases, regional planning schemes, and for other purposes (Table 5).

Soil pollution categories	Recommendations for soil use
Clean	Unlimited use
Acceptable	Use without restrictions, excluding high-risk objects
Moderately dangerous	Use during construction work for filling pits and excavations, in landscaping areas with adding a layer of clean soil of at least 0.2 m. Use for any crops, subject to quality control of agricultural products.
Dangerous	Limited use of excavations and pits for filling, covered with a layer of clean soil of at least 0.5 m. If there is an epidemiological danger, use after disinfection (disinfestation) as prescribed by the state sanitary and epidemiological service, followed by laboratory control. Use for industrial crops. Use for agricultural crops is limited, taking into account hub plants
Extremely dangerous	Removal and disposal at specialized landfills. If there is an epidemiological danger - use after disinfection (disinfestation) as prescribed by the state sanitary and epidemiological service with subsequent laboratory control. Use for industrial crops or exclude from agricultural use. Forest shelterbelts

1. Based on the data of the situational task, estimate:

1) physical properties of the soil and its ability to self-purify;

2) the degree of soil contamination with chemicals;

3) sanitary condition of the soil.

2. Give an opinion on the degree of contamination and danger of the soil in this area, indicate recommendations on the possible use of this soil.

Situational tasks to assess the degree of soil contamination and danger

Indicator Option	1	2	3	4	5
Mechanical composition
Foreign impurities, %
Sand particles >0.01 mm, %
Clay particles<0,01мм,%
Chemical composition
Lead, mg/kg			0,03		0,09
Copper, mg/kg	0,11		0,45		0,17
Fluorides, mg/kg			0,8	3,2	0,1
Xylenes, mg/kg	-	-	4,6	-	0,6
Nitrates, mg/kg			-	-
Surfactant, mg/kg	0,12	0,4	-	0,28	-
DDT, mg/kg	0,5	-	-	-	0,3
Benz(a)pyrene, mg/kg	-	0,14	0,7	0,02	0,08
Total number of bacteria in 1 g.	3 10 4	6,8 10 5	2 10 5	6 10 4	2,3 10 3
Coli-titer, g		7,6	0,05	0,012	0,01
Anaerobe titer, g	0,1	1,0	0,001	0,0005	0,3
Number of helminth eggs	-	-			-
	-	-			-
Indicator Option	6	7	8	9	10
Mechanical composition
Foreign impurities, %	0,5			0,9
Sand particles>0.01 mm,%
Clay particles>0.01mm,%	12,5			17,1
Chemical composition
Total organic nitrogen content in 100.0 g of soil, mg
Humus nitrogen content per 100.0 g			8,5
Lead, mg/kg	2,6				24,5
Copper, mg/kg	0,9	0,6	0,02	2,1	3,6
Fluorides, mg/kg	0,25		5,4		0,2
Xylenes, mg/kg	-	2,8		-	0,05
Nitrates, mg/kg
Surfactant, mg/kg	0,1	-	0,06	0,12	0,01
DDT, mg/kg		-	-	3,8	0,7
Benz(a)pyrene, mg/kg	-	0,15	0,1	0,002	0,4
Indicators of sanitary and epidemiological safety of soil
Total number of bacteria in 1 g.	3,1 10 4	4 10 5	1,2 10 5	5,2 10 3	1,3 10 4
Coli-titer, g	0,006	0,3	0,03	0,8	0,02
Anaerobe titer, g	0,008	0,02	0,5	0,016	0,08
Number of helminth eggs			-	-
Number of fly larvae and pupae per 25 m²			-	-

When assessing the ecological state of soils, it is very important to assess the content of both natural elements and compounds, and xenobiotic compounds. Assessment of soil contamination is carried out by comparing (contrasting) the content of polluting elements and substances in the studied soils, with their background content on the one hand, and on the other hand, with their maximum permissible content (MAC).

The maximum permissible concentration of a substance in the soil is a concentration that does not cause pathological changes (anomalies) during biological processes during long-term exposure to soil and plants, does not lead to the accumulation of toxic elements in plants and does not pose a danger to human health and life. MPC values ​​are determined experimentally, usually on sandy soils, based on several indicators of harmfulness, mainly for bulk forms, which does not allow drawing a conclusion about the flow power and availability of pollutants to plants. This makes the application of such standards controversial from both an environmental and economic point of view. Moreover, it is now almost universally recognized that component-by-component assessment of ecosystems does not provide satisfactory results. Comprehensive ecosystem standards are needed that could characterize the state of the ecosystem in question as a whole.

Since the hygienic danger of a particular concentration of pollutants depends on soil conditions, the creation of unified MPC standards encounters significant difficulties. It is no coincidence that currently MPCs have been established for only a little more than a hundred substances by which soil quality is controlled.

The principles for regulating chemicals in soils also differ from those for water bodies, atmospheric air, and food products. This is mainly due to the fact that the MPC standard for soil is based on its indirect impact on the human body through food.

The direct entry of harmful substances from the soil into the human body is limited and most often occurs through other media adjacent to the soil. Thus, the entry of pollutants into the human body occurs along the following paths: soil-plant-human, soil-plant-animal-human, soil-water-human, soil-atmospheric air-human.

Therefore, the issue of assessing soil pollution based on MPCs is very difficult. Currently, in many urbanized regions of Russia, and especially in Moscow, the condition of soils and soils, assessed according to accepted sanitary and hygienic methods (MPC), is close to critical, when the content of many pollutants exceeds these MAC from several to tens of times. In addition, this situation is complicated by the spatial heterogeneity of the content of pollutants and the discreteness of pollution sources.

The list of indicators of chemical pollution of soils and soils is determined based on the priority of the components of chemical pollution in accordance with the requirements of GOST 17.4.2.01-81 “Nature Conservation. Soils. Nomenclature of sanitary condition indicators”, SanPiN No. 2.1.7.1287-03 “Sanitary and Epidemiological requirements for soil quality”, GOST 17.4.1.02-83 “Nature conservation. Soils. Classification of Chemicals for Pollution Control.”

Hazard classes of chemical elements and substances in soils and soils

Currently, in accordance with SanPiN 2.1.7.1287-03 “Sanitary and epidemiological requirements for soil quality,” the chemical study of soils and soils during engineering and environmental surveys includes a standard and expanded list of indicators.
The standard list of chemical studies of soils and soils includes the definition of:

• content of heavy metals of hazard class 1 and 2: lead (Pb), cadmium (Cd), zinc (Zn), mercury (Hg), copper (Cu), nickel (Ni) and arsenic (As);
• content of 3,4-benz(a)pyrene and petroleum products.

An expanded list of studies is carried out in the presence of certain specific sources of soil and soil pollution by determining a more complete range of polluting chemicals. The choice of indicators of chemical pollution depends on the expected composition of pollutants, taking into account the nature of the source of contamination of soils and soils.
The main criterion for assessing the level of contamination of soils and grounds with chemicals is the maximum permissible concentration (MAC) or approximate permissible concentration (APC) of chemical elements (substances) in soils and soils (GN 2.17.2041-06 “Maximum permissible concentrations (MAC) of chemical substances in soil" and GN 2.1.7.2511-09 "Approximate permissible concentrations (APC) of chemicals in soil").

For the ecological and geochemical assessment of the condition of soils and soils, the following indicators are used:

• concentration coefficient relative to the maximum permissible concentration (MAC), characterizing the excess of the content of an element in soils and soils over its maximum permissible concentration (maximum concentration). The concentration coefficient relative to the TPC(MPC) is equal to the ratio of the content of the element in the object under study to its TPC(MPC):
  K ODK (maximum permissible concentration) = C i / ODK (maximum permissible concentration),
• concentration coefficient (Ksi) relative to the background, characterizing the intensity of the technogenic anomaly. The concentration coefficient is equal to the ratio of the element content in the object under study to its background content
  К сi = С i / С f, where
  C i is the actual content of the i-th chemical element in soils and soils, mg/kg;
  C phi is the background content of the i-th chemical element in soils and soils, mg/kg.

Background contents of gross forms of heavy metals and arsenic in soils (mg/kg)

Soils	Zn	Cd	Pb	Hg	Cu	Co	Ni	As
Sod-podzolic sandy and sandy loam	28	0,05	6	0,05	8	3	6	1,5
Soddy-podzolic loamy and clayey	45	0,12	15	0,10	15	10	20	2,2
Gray forest	60	0,20	16	0,15	18	12	35	2,6
Chernozems	68	0,24	20	0,20	25	25	45	5,6
Chestnut	54	0,16	16	0,15	20	12	35	5,2
Serozems	58	0,25	18	0,12	18	12	40	4,5

• total pollution indicator (Z c), characterizing the effect of exposure to a group of elements. The total pollution indicator is equal to the sum of the concentration coefficients of chemical elements
  Z c = K ci + ... + K cn - (n - 1) , where
  n is the number of chemical elements taken into account;
  K ci is the concentration coefficient of the i-th pollution component exceeding one.

The assessment of the danger of chemical pollution of soils and soils with heavy metals and arsenic is carried out according to the total pollution indicator (Zc) (Table 4.10). To calculate Zc, at least seven chemical elements should be used - Pb, As, Cd, Zn, Hg, Cu, Ni.

Rating scale of levels of chemical contamination of soils and soils with heavy metals and arsenic based on the total pollution indicator (Zс)

The assessment of the danger of chemical pollution of soils and soils with substances of organic origin is carried out based on its maximum permissible concentration (or permissible level) and hazard class. For organic compounds, their background content in soils and soils is equal to 0.1 MPC

Rating scale of levels of chemical contamination of soils and soils with substances of organic origin

Content	Category of soil and soil pollution
Hazard Class substances	1 class	2nd grade	3rd grade
> 5 MPC	Extremely dangerous	Extremely dangerous	Dangerous
From 2 to 5 MPC	Dangerous	Dangerous	Moderately dangerous
From 1 to 2 MPC	Acceptable	Acceptable	Acceptable

In case of multicomponent pollution, assessment of the level of chemical contamination of soils and soils is allowed based on the most toxic substance with the maximum content in soils and soils. The table provides an example of establishing a pollution category taking into account all pollution indicators.

Soils and grounds characterized by an extremely dangerous category of pollution, in accordance with the requirements of SanPiN 2.1.7.1287-03, are subject to removal and disposal at specialized landfills.

The classification of waste into a hazard class for the natural environment is carried out on the basis of the K indicator, which characterizes the degree of danger of the waste when it impacts the natural environment and is determined by calculation, in accordance with the Criteria for classifying hazardous waste as a hazard class for the natural environment, approved by order of the Ministry of Natural Resources Russia dated June 15, 2001 No. 511, according to the following formula:

K=K 1 + K 2 +……+ K n,

where: K – indicator of the degree of danger of waste to the environment;
K 1, K 2, K n – indicators of the degree of hazard of individual waste components, calculated according to the equation: K i = C i / Wi
C i is the actual content of the polluting chemical component in the soil (soil), mg/kg;
W i – hazard degree coefficient of the i-th component of hazardous waste, mg/kg;
n is the number of determined polluting chemical components.
The decision to assign soils to the waste hazard class is determined by the value of the hazard index according to Table 4.12.