What is meant by urban soil? Urban soil pollution

08.07.2020 | Documentation

Urban soils

The soil has a high buffering capacity, i.e. for a long time may not change its properties under the influence of pollutants. However, in the city it is one of the most polluted components of the environment. The soils of urban ecosystems are characterized by an uneven profile, strong compaction, changes in pH toward alkalization, and contamination with various toxic substances.

Features of the qualitative composition of microflora in urban soils have so far been studied only from the point of view of the presence of sanitary-indicative microbes in them. Soil microorganisms make up a significant part of any biogeosystem - an ecological system that includes soil, inert (non-living) and bio-inert (living or produced by living organisms) substances - and actively participate in its life activity.

Soil microorganisms are highly sensitive to anthropogenic impact, and in urban conditions their composition changes greatly. Therefore, they are good indicators of environmental pollution. Thus, by the type of microflora that predominantly lives (or, conversely, is absent) in a given area, it is possible to determine not only the degree of pollution, but also its type (which particular pollutant prevails in a given area). For example, indicators of severe anthropogenic pollution are the absence of coccoid forms of microalgae from the Chlorophyta division. The most resistant to pollution were filamentous forms of blue-green algae (cyanobacteria Cyanophyta) and green algae.

At the same time, microorganisms themselves are environmental cleaners. The fact is that the nutrients for many bacteria are substances that are absolutely inedible for higher organisms. In most cases, these substances (such as oil, methane, etc.) are direct sources of energy for such bacteria, without which they cannot survive. In some other cases, such substances are not vital for bacteria, but bacteria can absorb them in large quantities without harm to themselves.

By creating optimal conditions for microbial growth in properly designed engineered systems, waste treatment process rates can be significantly increased, facilitating the solution of many environmental biotechnology problems. Moreover, this discipline is gradually transforming from its usual function to a new phase characterized by maximum recovery of resources found in waste. Each territory has a certain technological capacity - that is, the amount of anthropogenic load that it is able to withstand without irreversible disruption of its functions. The introduction of appropriate microorganisms to contaminated areas significantly increases this indicator.

Solution environmental problems is based mainly on the foundation of biocatalytic methods due to their relative low cost and high productivity, and the entire subfield is called environmental biotechnology, which is currently the largest area of industrial application of biocatalysis, taking into account the volumes of processed substances. The philosophy within the framework of modern environmental biotechnology must be holistic in relation to all compartments of the environment, and this requires the integration of many scientific disciplines, and, first of all, detailed knowledge about the mechanisms of ongoing biocatalytic processes, as well as their effective engineering design.

To date, there are a number of biocatalytic and engineering approaches to protect the three main environmental compartments - soil, water and atmosphere. The main pollution of soils and water surfaces in the world is oil pollution. A number of microorganisms are able to effectively utilize oil and petroleum products, cleaning any surface from dangerous oil stains.

There is another unique and fairly widespread group of bacteria - methanotrophs, which use methane as the only source of carbon and energy. Interest in thermophilic methanotrophs is due to the prospects for their practical application both in science and in the field of ecology. Methanotrophic bacteria of the genera Methylocystis and Methylobacter are mainly found in biotopes.

Even before the adaptation of bacteria as biofilters and biopurifiers, before the advent of artificial pollutants, microorganisms already effectively performed a purifying role in nature. Recently, Russian scientists examined moss samples from various tundra swamps in northern Russia and discovered methanotrophic bacteria that live well in an acidic environment and at low temperatures right in the cells of sphagnum. The data obtained allowed scientists to assert that a methane-oxidizing bacterial filter operates throughout the entire territory of northern Russia from Chukotka and Kamchatka to the Polar Urals. This filter is closely related to sphagnum plants and is a physically organized structure that can control the flow of methane from peat bogs into the atmosphere.

Of course, in addition to methanotrophic and oil-refining bacteria, there are other species that process a number of other pollutants. Here are some processes for the processing of organic substances that are catalyzed by microorganisms: direct oxidation of propylene to 1,2-epoxypropane by molecular oxygen, direct oxidation of methane to methanol, microbial epoxidation of olefins, oxidation of gaseous hydrocarbons to alcohols and methyl ketones by atmospheric oxygen (with the participation of gas-assimilating microorganisms) , epoxidation of propylene by immobilized cells of gas-assimilating microorganisms. Moreover, while industrial processes for processing chemical pollutants usually require high temperatures, biocatalytic processes take place in microorganisms at a temperature usually within 20-40 degrees Celsius. And, if chemical processes produce a mass of by-products that are toxic in themselves (for example, during the oxidation of propylene into 1,2-epoxypropane with molecular oxygen, aldehydes, carbon monoxide, and aromatic organic substances are formed), then during the “work” of microorganisms such substances are not formed – they decompose into water and carbon dioxide, which are released by aerobic bacteria.

Currently, microorganisms have been developed that can utilize, that is, process to obtain energy for themselves, a huge amount of artificial substances - such as, for example, different kinds plastics, rubber, etc.

Assessing the state of organisms living in the soil and their biodiversity is important when solving problems of environmental practice: identifying zones of environmental distress, calculating the damage caused by human activity, determining the stability of the ecosystem and the impact of certain anthropogenic factors. Microorganisms and their metabolites allow early diagnosis of any environmental changes, which is important when predicting environmental changes under the influence of natural and anthropogenic factors.

In particular, among the main environmental protection and compensation measures, the identification of local (characteristic of a given ecological zone) strains of microorganisms that most actively utilize hydrocarbon raw materials, as the basis for carrying out these measures, has recently increasingly been mentioned.

Conducting surveys to identify degraded and contaminated lands for the purpose of their conservation and rehabilitation, as well as selection, development and implementation of optimal sets of environmental and compensation measures to reduce the negative anthropogenic impact on environment, adapted to local natural conditions and types of impact. The final step is to assess the state of ecosystems and the residual consequences of anthropogenic impact on the environment after environmental protection and reclamation measures are carried out.

In the modern world, microorganisms are actively used for bioremediation. They “work” on their own or as part of various biological products. New cleaning technologies based on microorganisms are being developed and existing ones are being improved. An example is one of the recent developments - biocatalytic technology for removing hydrogen sulfide and recovering elemental sulfur from polluted gases, which practically does not require the use of reagents.

Bacteria play the role of ecologists in a variety of areas of production. With their help, it is possible to clean not only the three non-biological (hydro-, litho-, atmosphere) and the so-called “living” (biosphere) shells of the Earth, but also to eliminate the consequences of accidents in exclusively anthropogenic zones - for example, in enterprises. Many microorganisms successfully cope with corrosion, many can fight their “brothers” - bacteria of pathogenic species, making the human environment suitable for work.

Bibliography

1. Zenova G.N., Shtina E.A. Soil algae. M., Moscow State University, 1991, 96 p.

2. Kabirov R.R. The role of soil algae in maintaining the stability of terrestrial ecosystems. // Algology, 1991.T.1, No. 1, pp.60-68.

3. Ryzhov I.N., Yagodin G.A. School monitoring of the urban environment. M., “Galaktika”, 2000, 192 p.

4. Lysak A.V.; Sidorenko N.N.; Marfenina U.E.; Zvyagintsev D.G.; Microbial complexes of urban soils. // Soil science. 2000, No. 1, p. 80-85.

5. Yakovlev A.S. Biological diagnostics and assessment. // Soil science. 2000. No. 1, pp. 70-79.

6. I. Yu. Kirtsideli, T. M. Logutina, I. V. Boykova, I. I. Novikova. The influence of introduced oil-degrading bacteria on complexes of soil microorganisms. // News of taxonomy of lower plants. 2001. T. 34

general characteristics
Soils within the city have certain specific properties, the most typical of which are: the presence of construction inclusions household waste; increased compaction; trend towards increased alkalinity; accumulation of technogenic substances; presence of pathogenic microorganisms.
The soil typical for the center of the old city is urbanozem on an ancient cultural layer, characterized by a thick dark-colored organic urbic horizon, the absence of a pronounced transitional horizon B and eluvial-illuvial differentiation of the profile. The urban soil profile often grows upward due to evaporation or anthropogenic input of material.
1 Basic data on the properties of urban soils were obtained from studying the soils of cities in the taiga natural zone (works by M.N. Stroganova et al., 1992, 1997, 1998).

Urbanozems are genetically independent soils that have both signs of zonal pedogenic processes and specific properties.
They are characterized by a surface organic-mineral bulk, mixed horizon with urban-anthropogenic inclusions, understood as a special natural-anthropo-technogenic formation.
In urban soils, despite the specificity of the soil profile and its high contamination with various types of solid inclusions, the following processes occur: humus formation and humus accumulation; removal and redistribution of mineral matter; iron-humus segregation; mobilization and immobilization of carbonates; gleying; structuring, including biogenic processing; as a result of human activity - the process of pollution with heavy metals and polycyclic aromatic hydrocarbons (PAHs); the appearance of pathogenic microorganisms; seasonal salinity.
The degree of expression of these processes varies and depends on the age of the sediment, the conditions of use of the site and a number of other circumstances. But the influence on soil formation of the main processes characteristic of this natural zone is undoubtedly.
Under certain circumstances, it is likely that urban soils developing on a cultural layer or on soils can evolve into zonal soils with their inherent properties and a system of genetic horizons.
Morphological properties of soils
A distinctive characteristic of urban soils, especially soils in the city center, is a large number of anthropogenic inclusions in the middle and lower parts of the soil profile. A significant place in the soil profiles of cities is occupied by bulk soil, which has at least one lithological break.
Over time, the surface layer acquires the features of the A1 horizon. There are buried horizons that are darker due to the accumulation of organic matter, have a looser consistency, and have an increased number of roots and animal populations.

Most urbanozems, as the central image of urban soils, are characterized by: the absence of natural soil horizons; the soil profile combines layers of artificial origin of different color and thickness, as evidenced by sharp transitions and smooth boundaries between them; skeletal material is represented mainly by construction and household waste (brick chips, pieces of asphalt, broken glass, coal, etc.) in combination with industrial waste, peat-compost mixture or inclusions of fragments of natural soil horizons; sometimes there are layers consisting entirely of waste and debris. /> Along with urban soils in the city, natural soils, as well as partially alluvial floodplain soils, are preserved in parks and forest parks varying degrees disturbed™. They combine the undisturbed lower part of the profile and anthropogenically modified upper layers (urban soils).
All of the listed soils differ in the city: by the nature of formation (bulk, mixed), by humus content and gley content, by the degree of disturbed profile, by the number and composition of inclusions (concrete, glass, toxic waste, etc.) and other indicators.
Types of morphological profiles are presented in Fig. 10.8.
Water-physical properties of soils
Urbanozems differ significantly from natural soils in physical properties (Table 10.4).
The granulometric composition of the soil is an important indicator that determines the productivity of urban soil, the degree of its filtration and water-holding capacity.
Table 10.4
Changes in the physical properties of urban soils (surface horizons)

For urban soils, the layering of soils in terms of granulometric composition has an important soil-geochemical significance, since it serves as a screening and capillary-interrupting barrier.
An important factor is the content of fine earth; it determines the degree of moisture capacity. Urban ecosystems are characterized by the introduction of sand and gravel into the soil, used in urban planning. Construction material, industrial waste, mechanical pollutants and other technological substrates have the size of gravel and stones. Because of this
their content in urban soils is constantly increasing.
Another important characteristic is the shape of the crushed stone. Many urban soils contain layers of hard, pointed debris, so such substrates exhibit little root penetration and sparse
occurrence of earthworms.
For urban soils, an important indicator is the clutter indicator, i.e. the degree of coverage of the soil surface with abiotic sediments, including toxic ones. This part of the soil can be called ballast. An important factor is the chemical composition of the material. When it is toxic, chemical pollution of the entire ecosystem occurs.
Urban phytocenoses that perform sanitary, hygienic and aesthetic functions are in harsh living conditions. One of the factors that causes depression or death of plants in urban conditions is high recreational load and, as a consequence,
trampling of ground cover and compaction of the soil surface. In such cases, it is difficult for roots to penetrate deep into the profile.
Density characterizes the ability of the soil to accumulate reserves of available moisture for plants, as well as air. Soil density affects moisture absorption, gas exchange in the soil, the development of plant root systems, and the intensity of microbiological processes. The optimal density of the arable horizon for most cultivated plants is 1.0-1.2 g/cm3, for urban soils it is higher (1.4-1.6 g/cm3). This value is a very important characteristic of soil cultivation.
As a rule, city soils are highly compacted from the surface. The limit of overconsolidation of the horizon and cessation of root development begins with a value of 1.4 g/cm3 for loamy soils and 1.5 g/cm3 for sandy soils.
The change in physical properties is associated with an increase in the volumetric mass of the surface layers of soil: in areas with increased traffic it reaches 1.7 g/cm3, although in bulk soils well fertilized with organic matter this value can be 0.8-0.9 g/cm3. V.D. Zelikov (19641) found that the state of green spaces depends on the ratio of loose and dense areas: if there are more than 30% of areas with soil volumetric mass above 1.1 g/cm3, then many trees suffer from dry tops. Gradual compaction leads to a change in the structure of soil horizons, the formation of layering and the formation of large-plate units (Rokhmistrov, Ivanova, 19852).
Strong soil compaction leads to the creation of conditions close to anaerobic in the root layer, especially during periods of prolonged rain in spring and autumn. In such conditions, the growth of small (active) roots of woody and herbaceous plants is greatly hampered and the process of natural regeneration of vegetation is disrupted. In compacted soils, the mass of roots is 2.5-3 times less than in uncompacted soils. Forest litter protects the soil well from overcompaction.
Research has also established that the soil hardness in compacted areas of the lawn, where thinning and poor grass growth was observed, was 40-45 kg/cm2, while for normal grass growth it is required that it be half as much (Abramashvili, 1985).
Porosity (porosity) is one of the most important soil properties, which mainly determines the water and air regime. From the value Zelikov V.D. Some materials on the characteristics of soils in forest parks, squares and streets of Moscow. // News of universities, Lesnoy railway. 1964. No. 3, p. 10-15. Rokhmistrov V.L., Ivanova T.G. Changes in soddy-podzolic soils in the conditions of a large industrial center // Pochvovedenie, No. 5, 1985, p. 71-76.
pores depend on the movement of water in the soil, water permeability and water-lifting capacity, and water mobility. In forest parks, gardens and boulevards, where the soil is almost not compacted, porosity ranges from 45 to 75%. Soil compaction reduces it to 25-45%, which leads to a deterioration in the water-air regime of the soil.
The moisture and air capacity of soils are related to porosity. With the deterioration of water-physical properties, the accumulation of moisture in it decreases, especially in summer months, amounting in compacted areas to only 14% of their moisture capacity.
Water permeability. An important characteristic of urban soils is the ability of the soil to absorb and pass through water coming from the surface. The magnitude and nature of water permeability strongly depend on the degree of rockiness, porosity of the soil, its moisture content and chemical composition. The presence of stones, cracks and voids in the soil of the city is essential. Urban soils are characterized by failed or patchy water permeability, caused by the presence of voids in the profile due to construction or household waste. There is a relationship between soil density and the rate of water filtration in it. For example, in the upper layers of soil in its natural state, water permeability is 60% higher compared to a moderately trampled area and four times higher compared to a heavily trampled area.
The presence of a path network with a highly compacted surface horizon disrupts the natural distribution of root mass, which can cause vegetation degradation.
Great importance to improve the environmental situation in the city and the health of its residents, the intensity of gas exchange between the urban soil and the atmosphere, as well as the composition of the gas phase of the soil, which is determined by the processes of transport of gases from the atmosphere and inside the soil, is determined. The gas composition of soils in the city is affected, in addition to soil density, soil moisture, etc., by the presence of the screening effect of artificial surfaces and leakage natural gas from the city gas pipeline network.
An asphalt coating, for example, almost completely screens the soil. One of the negative consequences hindered gas exchange is a reduced supply of oxygen: the diffusion coefficient of oxygen decreases from 3.8x10"2 cm2/s in open space to 5x10-5 cm2/s under an asphalt pavement. With this diffusion coefficient, if there are no other sources of oxygen supply, its amount is insufficient for vital activity of aerobic organisms and tree roots in a 10-centimeter layer of soil. However, oxygen can enter the soil under the asphalt from cracks and areas bordering the road, and there is a direct dependence of the amount of oxygen in the center of the road on its width.
The gas composition of soils is also affected by gas leaks from urban gas communications. In many countries Western Europe Cases have been recorded where this caused trees and shrubs to dry out in the city. This phenomenon probably occurs in our cities, but it does not seem to receive the attention it deserves.
When natural gas (mainly methane, ethane, propane) enters the soil, the intensity of microbiological oxidation of methane and other gases increases significantly (50-100 times) due to the active development of a specific group of anaerobic microorganisms, which increases the consumption of 02 and the production of CO2. Studies have shown that the composition of the gas phase of different soils around the leakage zones was similar. It was found that the area of influence of a gas leak depends on the intensity of the latter and can have a radius of up to 20 m, while completely anaerobic conditions are formed within a radius of up to 11 m. Around the anaerobic zone, a narrow (due to very high intensity) oxidation zone is formed, which, in turn, is surrounded by a zone of oxygen transit from unaffected areas. The listed zones have an almost regular spherical shape.
After eliminating a gas leak, significant changes occur in the number and composition of microorganisms and the composition of the gas phase of soils, but the return of the latter to its original state takes a period of several months to a year. The consequences of a gas leak may be the appearance of inorganic reducing agents (Fe2+, Mn2+, S2) or organic acids in the soil. Naturally, a gas leak, the consequences and after-effects of this phenomenon have an extremely negative effect on soil fauna and vegetation. In developed countries, the gas composition of soils in urban phytocenoses is sometimes regulated using specially developed methods, including the creation of ventilation channels and compressor treatment of soils in root distribution zones (Craul, 19921).
Recognizing the critical importance of green spaces in urban environments and important role soil and its ecological functions for plant growth, it is necessary to state the following:
Increased gravelly and carbonate content of urban soils, lack of structure, overcompaction and high hardness of surface layers negatively affect the water-physical properties of both artificially created and preserved natural soils of the city and, consequently, the functioning of urban phytocenoses and the entire urban ecosystem.
1 Craul R. G. Urban soils in landscape design. New-York. 1992.

Physicochemical properties of soils
Most emissions of various substances and materials, including toxic Bely I, into the urban environment are concentrated on the soil surface, where they gradually accumulate. This leads to a change in the chemical and physicochemical properties of the substrate.
In terms of basic physical and chemical indicators, city soils differ significantly from their natural counterparts. Table data 10.5 illustrate the difference in the properties of urban soils in Moscow and soddy-podzolic soils in the Moscow region. Probably in other natural areas Some trends in these differences may be different.
Table 10.5
Comparative characteristics properties of surface horizons of urban soils in Moscow and soddy-podzolic soils of the Moscow region
(Stroganova, Agarkova, 1992)

The acidity value of the root layer of urban soils varies widely, but soils with a neutral and slightly alkaline environment predominate. In most cases, the environmental response in urban soils is higher than in zonal soils (Obukhov et al., 1989, 1990). Most authors associate the high alkalinity of urban soils with the penetration into them through surface runoff and drainage water of mainly calcium and sodium chlorides, as well as other salts that are sprinkled on sidewalks and roads in winter. Another reason is the release of calcium under the influence of precipitation from various debris, construction waste, cement, bricks, etc., which have an alkaline reaction. Almost everywhere there is a gradual decrease in pH with depth.
As is known, increasing acidity to values close to neutral favors the growth of most plants and promotes the activity of microorganisms, as well as the binding of some soluble compounds of heavy metals. However, further alkalization can lead to the formation of poorly soluble forms of some nutrients and microelements, and, starting with pH values of 8-9, makes the soil unsuitable for the growth of most plants.
The content of organic carbon in urban soils varies and depends on its value in the original substrate, as well as on the use of organic and mineral fertilizers, the introduction of organic waste, etc. As a rule, the amount of organic matter in urban soils is higher than in background soils.
In all ancient soils, especially the soils of squares, parks, and vegetable gardens, the humus content reaches 8-12%, and on average 4-6% (Zemlyanitsky et al., 1962; Lepneva, Obukhov, 1987"). With depth it is somewhat falls, often having an abrupt distribution along the profile. Sometimes “old-fill” soils acquire the character of chernozem-like, as noted by L.T. Zemlyanitsky et al. (1962) for the Alexander Garden of Moscow.
In young soils of the city, the composition of organic matter is dominated by compost components and low-humified fulvic acid fraction.
The degree of base saturation often exceeds 80-95% and reaches 100%. For soils in most parks and urban forests it is usually less. The composition of exchangeable cations is dominated by Ca (up to 70%) and Mg (up to 30%).
Plant nutrition elements (N, P, K) are distributed unevenly in urban soils. Most researchers note the high enrichment of urbanozems and slightly disturbed soils with total nitrogen, phosphorus and potassium. They are also enriched in mobile forms of nutrients. For bulk soils in Moscow L.T. Zemlynitsky and co-authors (1962) noted a high supply of mobile phosphorus (up to 100-200 mg/100 g of soil and more); data on provision 1 Lepneva O.M., Obukhov A.I. Heavy metals in soils and plants on the territory of Moscow State University. // News. Moscow State University, ser. 7. No. 1, 1987.
The levels of available potassium are quite varied, sometimes the analysis reveals only traces of mobile potassium, and sometimes the value reaches 40 mg/100 g or more.
Urban soil pollutants. Since the sixties of the XX century. To this day, urban ecologists and soil scientists are interested in the problem of contamination of urban soils with heavy metals. It should be noted that this type of soil contamination is the most studied, since almost every publication devoted to urban soils contains information about contamination with microelements. Most urban ecologists believe that all urban soils are contaminated with heavy metals. Currently, for many large cities of the world it has been established that heavy metals enter the soil mainly from the air. In urban areas, the greatest attention is drawn to pollution with elements such as Pb, As, Cu, Zn, Cd, Ni.
Heavy metals are involved in the biological cycle, transmitted through food chains and cause a number of negative consequences. With the maximum manifestation of the process of chemical pollution, the soil loses its ability to be productive and biologically self-purifying, there is a loss of ecological functions and the death of the urban system. The composition, structure and abundance of microflora and mesofauna change. “Overloading” the soil with heavy metals can completely or partially block the course of many biochemical reactions. Heavy metals reduce the rate of decomposition of soil organic matter.
The history of land use in old cities is quite complex. Heavy metal pollution may have occurred as a result of craft and industrial activities in past centuries, as a result of the destruction and construction of buildings after wars. In general, when land use changes in different times There was an accumulation of substrates with different properties, including those contaminated with heavy metals.
Motor transport is recognized as one of the main sources of pollution in cities. Experts count about 40 chemicals in exhaust gases, most of them toxic. There is especially a lot of toxic lead; its increased concentrations are found at a distance of more than 100 m from the highway.
Much attention Researchers are focusing on soil contamination with deicing compounds. Since the beginning of the seventies, regular studies have been carried out in Western European countries on the influence of NaCl, CaC12 and Ca(N03)2, which are sprinkled on roads in winter, on the properties of soils along roads. The accumulation of salts in the soil can be observed at a distance of 100 m from the road, but it is significant at a distance of the first 5-10 m. The maximum salt content occurs at early spring, at least for September-October. By autumn, Na moves from the surface horizon (0-5 cm) to deeper layers, C1 is washed out. At a distance of 10 m from the road of ten years of operation, Na accumulates in an amount of 50-70 mg/kg. There is evidence of an increase in the pH of the soil solution. Sprinkling roads with salt leads to increased dispersion, deterioration of soil moisture conductivity and aeration. The issue of the aftereffects of chlorides and exhaust gases requires further in-depth and thorough research.
Other pollutants common in urban environments include: various shapes pesticides inherited from agricultural landscapes and characteristic mainly of new urban areas; organic waste (liquid effluent from livestock farms, industrial organic waste, wastewater); radionuclides; mercury; substances entering the soil with contaminated precipitation.
Inclusions of anthropogenic materials extremely strongly affect all soil properties, limiting the area of possible penetration of roots and the spread of microorganisms, and reduce the water-holding capacity of soils. Calcium containing construction garbage, dust, cement chips and similar materials contribute to alkalization, and the decomposition of other substrates (plastic, etc.) leads to the release of toxic substances and gases.
The most important factor influencing the properties of urban soils is their contamination with heavy metals, pesticides, organochlorine compounds and other toxicants.
Currently, extensive materials have been obtained on the levels of soil pollution in various cities of the CIS and abroad. For 120 cities in Russia, in 80% of cases, significant excesses of the approximate permissible concentrations (APC) of lead and other heavy metals in the soil were noted. More than 10 million urban residents come into contact with soil that, on average, exceeds the maximum permissible concentration for lead. In most cities, the lead content varies between 30-150 mg/kg with an average value of 100 mg/kg.
To a large extent, these indicators are determined by the type of pollution source, the quantitative and qualitative composition of emissions, the distance of pollutants from the source of pollution, and are specific to each city and any area in it. The distribution of pollutants over the soil surface is determined by many factors. It depends on the characteristics of pollution sources, wind patterns, geochemical migration flows, and landforms.
The degree of manifestation of the pollution process is determined as the ratio of the content of a pollutant in the soil to the MPC value or another standard value. Chemical pollution with heavy metals is determined by their bulk and mobile forms.

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FEDERAL EDUCATION AGENCY

STATE EDUCATIONAL INSTITUTION

HIGHER PROFESSIONAL EDUCATION

URAL FEDERAL UNIVERSITY

Department of Biology

Department of Ecology

Report

on the topic: "Diversity of soils and soil-like bodies in urban ecosystems"

Novikova Evgenia

teacher: doctor of biology sciences,

Professor Makhonina Galina Ivanovna

Ekaterinburg - 2011

An analysis of domestic literature reveals not only the absence of urban landscape soils in the national classification of Russia, but also the disunity of researchers in this direction.

Closer to this problem is the classification of anthropogenically transformed soils and soil-like surface formations, proposed by a group of employees of the Soil Institute named after. Dokuchaev, which was the result of a generalization of many years of work by scientists from Russia and the CIS countries, fits into the general classification of soils in Russia.

Based on this development and on the study of various approaches to the problem of systematics and classification of urban soils in Russia, in the near and far abroad and G.V.’s own research. Dobrovolsky proposed the following classification of soils in the taiga zone. It is based on the features of the profile-genetic (morphological) structure of the soil profile as a fairly simple and universal approach, as well as on the nature of the soil-forming rocks and soils. This classification was developed for soils in cities in central Russia.

All soils of the city are divided into groups of soils: natural undisturbed, natural anthropogenic, surface-transformed (naturally disturbed), anthropogenic deeply transformed urbanozems and soils of technogenic surface soil-like formations - urbantechnozems.

The main difference between urban soils and natural soils is the presence of a diagnostic “urbic” horizon. This is a surface bulk, mixed horizon, part of the cultural layer with an admixture of anthropogenic inclusions (construction and household waste, industrial waste) of more than 5%, with a thickness of more than 5 cm. Its upper part is humified. An upward growth of the horizon is observed due to atmospheric dust fallout and aeolian movements. urbantechnozem taiga soil anthropogenic

Natural undisturbed soils retain the normal occurrence of natural soil horizons and are confined to urban forests and forested areas located within the city.

Table. Classification of urban soils in the taiga zone

Soil block	Natural soils within the city	Natural-anthropogenic soils	Anthropogenic transformed	Technogenic surface soil-like formations
Soil class	Natural soils	Surface-transformed natural soils	Anthropozems: anthropogenic deeply transformed soils	Surface-humused technozems (artificially created)
Urban soil type	Podzolic, bog-podzolic, alluvial, sod-gley, etc. with signs of urbogenesis	The same, but with transformation, less than 50 cm of the profile is affected (urban soil)	Urbanozems: transformation affected more than 50 cm of the profile	Urbotechnozems (soils)
Soil subtype	Sod-podzolic, swamp-podzolic and others	The same, but broken, scalped, bulked, etc.	1. Urbanozem 2. Kulturozem 3. Ekranozem 4. Necrozem 5. Industrializem 6. Intruzem	1. Replantozem 2. Constructozem

Naturally anthropogenic surface-transformed soils in the city are subject to surface changes in the soil profile of less than 50 cm in thickness. They combine an urbic horizon less than 50 cm thick and an undisturbed lower part of the profile. The soils retain the type name indicating the nature of the disturbance. Currently, there are no strict nomenclature names for such soils, since they have not been developed in the general national classification of soils in Russia.

Anthropogenic deeply transformed soils form a group of urban soils proper, urbanozems, in which the “urbic” horizon has a thickness of more than 50 cm. They are formed due to urbanization processes on the cultural layer or on bulk, alluvial and mixed soils with a thickness of more than 50 cm, and are divided into 2 subgroups: 1) physically transformed soils in which a physical and mechanical restructuring of the profile has occurred (urbanozem, culturozem, necrozem, ekranozem); 2) chemically transformed soils, in which significant chemogenic changes in the properties and structure of the profile have occurred due to intense chemical pollution by both air and liquid, which is reflected in their separation (industrizem, intruzem).

In addition, soil-like technogenic surface formations (urbotechnozems) are formed on the territory of cities. They are artificially created soils by enriching them with a fertile layer, peat-compost mixture of bulk or other fresh soils (replanozem, constructozem).

Anthropogenically transformed and artificially created soils can be diagnosed based on the following characteristics:

Type "Urbanozem".

A. Physically transformed:

1. Urbanozems (actually) - the soil profile consists of a series of diagnostic horizons U1, U2, etc., from a peculiar silty-humus substrate of varying thickness and quality with an admixture of urban waste; can be underlain with impermeable material (asphalt, foundation, concrete slabs, communications). They are characterized by the absence of genetic horizons to a depth of 50 cm or more. Formed on soils of different origins and on the cultural layer.

2. Cultural soils - urban soils of fruit and botanical gardens, old vegetable gardens. They are characterized by a large thickness of the humus horizon, the presence of humus-peat-compost layers more than 50 cm thick, developing on the lower illuvial part of the soil profile, on the cultural layer or on soils of different origins.

3. Necrozems - soils included in the soil complex of city cemeteries. Soil mixing is more than 200 cm.

4. Ekranozems - screened soils (the name is conditional). They are formed under asphalt concrete pavement and stone. They are also called paved, sealed.

B. Chemically transformed:

Chemically transformed and contaminated soils may also include technogenically polluted soils in which the genetic profile is preserved.

5. Industrial soils - soils of industrial and communal zones. Heavily technogenically polluted with heavy metals and other toxic substances that change the soil-absorbing complex of soils, extremely reduce the biodiversity of soil biota, and make the soil almost abiotic. Compacted, structureless, with inclusions of toxic non-soil material of more than 20%. The name is conditional; they can also be called “pollutozem”.

6. Intruzems - soils saturated with organic oil-gasoline liquids. They form on the territory of gas stations and car parks when oil and gasoline constantly penetrate into the ground. The name is conditional; they are also proposed to be called “urbochemozem”, “petroleum soil”.

Type "Urbotechnozem".

Surface-humused urbotechnozems.

In cities and in areas of mass construction, artificially created surface formations are formed, which in their properties are close to Technozems, but differ from them in some features that bring them closer to soils, which were previously called “soil-soil”.

Urban technozems (underdeveloped, young, primitive) differ in thickness and properties, humus layer, composition and properties of the rock.

1. Replantozems - soils that consist of a thin humus layer, a layer of peat-compost mixture or a layer of organic-mineral substance applied to the surface of the reclaimed rock. They are mainly formed in areas of urban industrial and residential new buildings, on new lawns. The term “replantozem” was introduced by I.A. Krupenikov and B.P. Podymov.

2. Constructozems are artificially purposefully created soils, consisting of layers of soil of different granulometric composition and origin and bulk fertile layer. Currently, these soils in cities are not constructed and are considered as a problem for future work.

In addition to these soil-like formations, in cities there are landfill sites with weakly humified and non-humused mineral soils.

Most of the territories of large cities are represented by urban soils, and the areas of new buildings and construction sites are represented by urban-technozems, but along with them, the city also contains natural soils of varying degrees of disturbance.

In slightly disturbed soils, disturbances affect humus-accumulative horizons (up to 10-25 cm); in heavily disturbed soils, the depth of disturbance reaches the illuvial horizons (up to 25-50 cm). Buried soils include urban soils that have preserved the entire soil profile or some of its upper part under the anthropogenic strata.

The origin of soil-forming rocks is of great importance for the classification of urban soils.

Soil formation in cities occurs on soil-forming rocks of different composition, genesis, physical and chemical properties. There are three types of soil formed: mixed (on site), bulk (imported) or alluvial.

In urban landscapes, on reclaimed bulk and alluvial soils, over time, some signs of initial soil formation, rock structuring, gleyization, humus formation, etc. can be observed, that is, the evolution of soils begins from primitive urban-technozems to urbanozems, and the latter, with long-term exposure, evolve in the direction of natural soils. soil

Literature

1. Stroganova M.N., Agarkova M.G. Urban soils: experience in studying and systematics (On the example of the southwestern part of Moscow).//Vest. Moscow State University, series 17. 1992, No. 7, p. 16-24.

2. Stroganova M.N., Myagkova A.D., Prokofieva T.V. Urban soils: genesis, classification, functions. - The soil. City. Ecology. Ed. G.V. Dobrovolsky. M., 1997, p. 15-85.

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Total soil contamination with chemical elements

Zinc, lead, copper, and mercury are widely distributed and actively accumulate in soils. Mainly at background concentrations they contain molybdenum, nickel, tin, barium, chromium, cadmium, beryllium, cobalt and boron.

A study of the soil cover showed that about 43% of the city's area falls into the category of weak (acceptable) pollution (Zc less than 16). Soils with an average (moderately dangerous) level of pollution (Zc 16-32) occupy 28% of the entire territory. On 27% of the area, severe (dangerous) soil contamination was detected (Zc 32-128), and on 2% the maximum (extremely dangerous) level was recorded (Zc more than 128).

Soils with acceptable levels of contamination are distributed mainly on the periphery of Moscow, mainly in the west and southwest, and are confined to large urban forest parks. Such soils are found fragmentarily in the north, south and east of the city ().

Heavily contaminated soils stretch in a wide strip from northwest to southeast, covering the central part of the city.

Foci of maximum soil contamination have been identified mainly in the area of industrial zones or are located in their zone of influence. Most of these outbreaks were recorded in the Central, South-Eastern, Southern and Eastern districts.

Lowest concentration chemical elements in the soils of Western administrative district.

Depending on the functional purpose of the territories, the level of chemical elements in soils decreases in the following order: industrial zones (Zc 45) - squares, boulevards, residential areas (Zc 31) - cultural and recreation parks (Zc 28) - wastelands (Zc 21) - natural and national parks (Zc 12-13).

The soils of industrial zones are subject to the most powerful technogenic pressure; here, even the average value of the pollution index (Zc) corresponds to a dangerous level of pollution. The soils of public gardens, boulevards and residential areas are also approaching dangerous levels of pollution. Squares and boulevards are usually located near highways and are exposed to vehicle emissions. The main sources of soil pollution in residential areas are municipal waste and vehicles.

Soil contamination with individual chemical elements

The main soil pollutants in the city are zinc, lead, copper, cadmium, tin, molybdenum and chromium.

Below is a brief description of distribution of widespread and most toxic chemical elements in soils in the city.

Mercury

The established concentrations of mercury in soils in Moscow range from 0.02 to 2.1 mg/kg, with an average content of 0.2 mg/kg. Elevated concentrations metals are typical for the Central and South-Eastern districts of the capital.

In general, mercury contamination of city soils is insignificant and does not pose an environmental hazard.

Cadmium

Concentrations of this element in soils of the city of Moscow vary widely with an average value of 0.3 mg/kg, which is significantly lower than the established MPC (2 mg/kg).

The highest concentrations of the element are characteristic of the South-Eastern, Southern and Central districts.

Contamination of soils in the city of Moscow with cadmium is manifested to a greater extent than mercury pollution, but in general it is assessed as low.

Lead

Widely distributed in the city's soil cover, its average content is 96.5 mg/kg. The distribution of lead in the city is shown in Fig. 6.5.2.

On approximately 20% of the city's area, the concentration of lead in the soil exceeds the MEC value (130 mg/kg), and on 5% of the territory, the concentration of the element exceeds the MAC by more than 2 times. Soils with lead concentrations less than the maximum concentration limit are distributed mainly on the periphery of the city. The soils of the Central Administrative District are most contaminated, and the least contaminated are those of the Western and Southwestern districts.

In comparison with the monitoring results of 2006, there was an increase in the lead content in Moscow soils, which is undoubtedly due to the constantly increasing number of vehicles in the city and the continued use of gasoline with lead additives.

Zinc

The most contaminated soil is in the districts of Central Administrative District, North-Eastern Administrative District, Southern Administrative District, South-Eastern Administrative District and Eastern Administrative District, where contaminated soil with contents close to the UEC occupies about 70-80% of the area. The least contaminated soil is the western sector of the city - the districts of the North-Western Administrative District, the Western Administrative District, and the South-Western Administrative District ().

Soils with zinc concentrations less than 0.5 TAC in surface horizons are distributed mainly on the periphery of the city, but relatively small areas of soils relatively uncontaminated with zinc are found throughout its territory.

Copper

On 91.5% of the city's area, the copper content is below the APC value (less than 132 mg/kg). At the same time, in the territory of ZAO and SZAO, and in other districts in the zone from the regional railway to the city borders, the copper content usually does not reach 0.5 ADC. In the central part of the city, concentrations ranging from 0.5 to 1 TAC value predominate. On 7.5% of the city's territory the copper content is at the level of 1-2 OPC, only on 1.4% of the territory it is 2-4 OPC and on 0.6% of the area it is above 4 OPC values.

Chromium

The average chromium content in the city's soils is about 58 mg/kg. The average concentrations of the element in the soils of administrative districts differ slightly and do not exceed the maximum permissible contents (MPC 90 mg/kg). The highest concentrations of chromium were found in the soils of the southern sector of the city; the least contaminated soil was in the Western and Northwestern districts.

On 7.5% of the city's territory, chromium contents exceed the maximum permissible concentrations in soils (MPC) by up to 2 times, and only on 1.2% of the surveyed area do they exceed 2 MACs.

Nickel

The results of the study allow us to assess the contamination of urban soils with nickel as insignificant and not posing a significant environmental hazard.

Manganese

Increased contents of the specified element were identified in the territories national park Losiny Island and natural park Bitsa. Contents close to the background analogue were recorded in the Tsaritsyno, Troparevsky, Filevsky parks, and in the Serebryanoborsky forestry. In the rest of the city, the manganese content in soils is generally below the background value.

Thus, the analysis of the content of heavy metals in the city’s soils showed that, according to the total pollution indicator (Zc value), the existing technogenic pollution of the city’s soil cover on 43% of the territory is characterized by a low level and a satisfactory environmental situation. On 28% of the area, an average level of pollution was recorded, and on 29%, high and maximum levels of pollution were recorded, which allows them to be classified as areas with an increased risk to the health of the population living here.

Each region of our country has its own soil types. Their formation was influenced not only by climate and relief, but also by vegetation and animal world. Today we will talk about the types of soils and what crops can be grown on them.

What is soil?

The first who began to study the issue of studying soil was the Soviet scientist V.V. Dokuchaev. He found out that each region has its own soil types. After much research, the scientist concluded how the terrain, vegetation, animals, The groundwater influence the fertility of the land in a particular region. And, based on this, he proposed his own classification. They were given full characteristics soil

Of course, each country is guided by the international or its own local table of differentiation of the top layer of the earth. But today we will look at Dokuchaev’s classification.

Types of soils and plants suitable for them

Characteristics of sandy loam soils

Sandy loam soils are another type of soil that is favorable for growing cultivated plants. What are the characteristics of this type of land?

Due to its light structure, such soil perfectly allows air and water to pass through it. It is also worth noting that it retains moisture and some minerals well. Thus, sandy loam soils can enrich all plants growing in them.

During rains or irrigation, such soil quickly absorbs water and does not form a crust on its surface.

Sandy loam soils warm up quickly. Thus, already in early spring they can be used as soil for planting seeds or planting cuttings.

To make your land more fertile, it is recommended to add peat to it. It will help improve the structure of this soil. As for nutrients, to enrich the land with them it is necessary to add compost or manure to it. This needs to be done often. As a rule, summer residents pour prepared humus diluted with water onto the roots of plants, which ensures rapid growth and enrichment with minerals and nutrients.

How can you determine soil fertility?

We have already figured out that all types of soil differ from each other not only in composition, but also in their suitability for growing certain plants in them. But is it possible to determine the fertility of the soil in your dacha yourself? Yes, it's possible.

First of all, you must understand that the amount of nutrient minerals in the soil depends on acidity. Therefore, in order to decide whether it is necessary to improve its composition or not by adding fertilizers, it is necessary to know its acidity. The norm for all soils is pH 7. Such soil perfectly absorbs the necessary nutrients and enriches all the plants growing in it with them.

So, in order to determine the pH of the soil, you need to use a special indicator. But, as practice shows, sometimes this method is not reliable, since the result is not always true. Therefore, experts recommend collecting a small amount of soil from different places in the dacha and taking it to the laboratory for analysis.

What is meant by urban soil? Urban soil pollution

Urban soils

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Total soil contamination with chemical elements