At thermal power plants, people receive almost all the necessary energy on the planet. People have learned to get electricity otherwise, but still do not accept alternatives. Even though it is unprofitable for them to use fuel, they do not refuse it.

What is the secret of thermal power plants?

Thermal power plants It is no coincidence that they remain indispensable. Their turbine generates energy in the simplest way, using combustion. Due to this, it is possible to minimize construction costs, which are considered fully justified. In all countries of the world there are such objects, so you can not be surprised at the spread.

The principle of operation of thermal power plants built on burning huge amounts of fuel. As a result of this, electricity appears, which is first accumulated and then distributed to certain regions. Thermal power plant schemes remain almost constant.

What fuel is used at the station?

Each station uses a separate fuel. It is specially supplied so that the workflow is not disturbed. This point remains one of the problematic, as transport costs appear. What types of equipment does it use?

• Coal;
• oil shale;
• Peat;
• fuel oil;
• Natural gas.

Thermal schemes of thermal power plants are built on certain form fuel. Moreover, minor changes are made to them, providing maximum ratio useful action. If they are not done, the main consumption will be excessive, therefore, the received electric current will not justify.

Types of thermal power plants

Types of thermal power plants - important question. The answer to it will tell you how the necessary energy appears. Today, serious changes are being gradually introduced, where the main source will be alternative views, but so far their use remains impractical.

1. Condensing (CES);
2. Combined heat and power plants (CHP);
3. State district power plants (GRES).

TPP power plant will require detailed description. The species are different, so only a consideration will explain why construction of such a scale is being carried out.

Condensing (CES)

Types of thermal power plants begin with condensation. These CHP plants are used exclusively for generating electricity. Most often, it accumulates without immediately spreading. The condensation method provides maximum efficiency, so these principles are considered optimal. Today, in all countries, separate large-scale facilities are distinguished, providing for vast regions.

Nuclear plants are gradually appearing, replacing traditional fuel. Only replacement remains a costly and time-consuming process, as fossil fuel operation is different from other methods. Moreover, it is impossible to turn off a single station, because in such situations entire regions are left without valuable electricity.

Combined heat and power plants (CHP)

CHP plants are used for several purposes at once. They are primarily used to generate valuable electricity, but fuel combustion also remains useful for heat generation. Due to this, thermal power plants continue to be used in practice.

An important feature is that such thermal power plants are superior to other types of relatively small power. They provide individual areas, so there is no need for bulk supplies. Practice shows how profitable such a solution is due to the laying of additional power lines. The principle of operation of a modern thermal power plant is unnecessary only because of the environment.

State District Power Plants

General information about modern thermal power plants do not mark GRES. Gradually, they remain in the background, losing their relevance. Although state-owned district power plants remain useful in terms of energy generation.

Different types thermal power plants provide support to vast regions, but still their capacity is insufficient. In Soviet times, large-scale projects were carried out, which are now closed. The reason was the inappropriate use of fuel. Although their replacement remains problematic, since the advantages and disadvantages of modern TPPs are primarily noted by large amounts of energy.

Which power plants are thermal? Their principle is based on fuel combustion. They remain indispensable, although calculations are being actively made for an equivalent replacement. Thermal power plants advantages and disadvantages continue to be confirmed in practice. Because of what their work remains necessary.

ORGANIZATIONAL AND PRODUCTION STRUCTURE OF THERMAL POWER PLANTS (TPP)

Depending on the capacity of the equipment and schemes of technological connections between the stages of production at modern TPPs, shop, non-shop and block-shop organizational and production structures are distinguished.

Workshop organizational and production structure provides for the division of technological equipment and territory of TPP into separate sections and assigning them to specialized units - workshops, laboratories. In this case, the main structural unit is a workshop. Shops, depending on their participation in production, are divided into main and auxiliary. In addition, TPPs can include non-industrial households (housing and subsidiary farms, kindergartens, rest houses, sanatoriums, etc.).

Main workshops are directly involved in energy production. These include the fuel and transport, boiler, turbine, electrical and chemical shops.

The composition of the fuel and transport shop includes sections of the railway facilities and fuel supply with a fuel warehouse. This workshop is organized at power plants that burn solid fuel or fuel oil when it is delivered by rail.

The composition of the boiler shop includes areas for supplying liquid or gaseous fuels, dust preparation, ash removal.

The turbine shop includes: heating department, central pumping station and water management.

With a two-shop production structure, as well as at large TPPs, the boiler and turbine shops are combined into a single boiler-turbine shop (KTTs).

The electrical workshop is in charge of: all electrical equipment of the thermal power plant, an electrical laboratory, an oil economy, an electrical repair shop.

The chemical plant includes chemical laboratory and chemical water treatment.

Auxiliary shops serve the main production. These include: a shop for centralized repair, repair and construction, thermal automation and communications.

Non-industrial farms are not directly related to energy production and serve the domestic needs of TPP workers.

Workshopless organizational and production structure provides for the specialization of divisions in the performance of the main production functions: operation of equipment, its maintenance, technological control. This causes the creation of production services instead of workshops: operation, repairs, control and improvement of equipment. In turn, production services are divided into specialized sections.

Creation block-shop organizational and production structure due to the emergence of complex energy units-blocks. The block equipment carries out several phases of the energy process - fuel combustion in a steam generator, electricity generation in a turbogenerator, and sometimes its transformation in a transformer. In contrast to the workshop, with a block-shop structure, the main production unit of the power plant is the blocks. They are included in the CTC, which are engaged in the centralized operation of the main and auxiliary equipment boiler blocks. The block-shop structure provides for the preservation of the main and auxiliary shops that take place in the shop structure, for example, the fuel and transport shop (TTTS), chemical, etc.

All types of organizational and production structure provide for the implementation of production management on the basis of unity of command. At each TPP there is an administrative, economic, production, technical and operational dispatch department.

The administrative and economic head of the TPP is the director, the technical manager is the chief engineer. Operational and dispatching control is carried out by the duty engineer of the power plant. Operationally, he is subordinate to the EPS dispatcher on duty.

Name and quantity structural divisions, and the need to introduce separate positions is determined depending on the standard number of industrial and production personnel of the power plant.

The specified technological and organizational and economic features of electric power production affect the content and tasks of activity management energy enterprises and associations.

The main requirement for the electric power industry is a reliable and uninterrupted power supply to consumers, covering the required load schedule. This requirement is transformed into specific indicators that evaluate the participation of the power plant and network enterprises in the implementation of the production program of energy associations.

For the power plant, the readiness to carry the load is set, which is set by the dispatch schedule. For network enterprises, a schedule for repairs of equipment and facilities is established. The plan also sets out other technical and economic indicators: specific fuel consumption at power plants, reduction of energy losses in networks, and financial indicators. However manufacturing program energy enterprises cannot be rigidly determined by the volume of production or supply electrical energy and warmth. This is impractical due to the exceptional dynamism of energy consumption and, accordingly, energy production.

However, the volume of energy production is an important calculation indicator that determines the level of many other indicators (for example, cost) and the results of economic activity.

Content heavy metals(HM) in soils depends, as established by many researchers, on the composition of the initial rocks, a significant variety of which is associated with a complex geological history development of territories. The chemical composition of soil-forming rocks, represented by the weathering products of rocks, is predetermined chemical composition source rocks and depends on the conditions of hypergene transformation.

AT recent decades in the processes of HM migration to natural environment turned on intensively anthropogenic activity humanity.

One of the most important groups of toxicants that pollute the soil are heavy metals. These include metals with a density of more than 8 thousand kg / m 3 (except noble and rare): Pb, Cu, Zn, Ni, Cd, Hg, Co, Sb, Sn, Be. In applied works, Pt, Ag, W, Fe, and Mn are often added to the list of heavy metals. almost all heavy metals are toxic. Anthropogenic dispersion of this group of contaminants (including in the form of salts) in the biosphere leads to poisoning or the threat of poisoning living things.

Table one.

Table 1. Classification of chemicals by hazard classes

Copper- is one of the most important irreplaceable elements necessary for living organisms. In plants, it is actively involved in the processes of photosynthesis, respiration, restoration and nitrogen fixation. Copper is part of a number of oxidase enzymes - cytochrome oxidase, ceruloplasmin, superoxide dismutase, urate oxidase and others, and is involved in biochemical processes as an integral part of enzymes that carry out oxidation reactions of substrates with molecular oxygen.

Clark in earth's crust 47 mg/kg. Chemically, copper is an inactive metal. The fundamental factor influencing the value of Cu content is its concentration in soil-forming rocks. Of the igneous rocks, the largest amount of the element is accumulated by the main rocks - basalts (100-140 mg/kg) and andesites (20-30 mg/kg). Covering and loess-like loams (20-40 mg/kg) are less rich in copper. Its lowest content is noted in sandstones, limestones and granites (5-15 mg/kg). The metal concentration in clays of the European part of Russia reaches 25 mg/kg, in loess-like loams – 18 mg/kg. Sandy and sandy soil-forming rocks of the Altai Mountains accumulate an average of 31 mg/kg of copper, south Western Siberia– 19 mg/kg.

In soils, copper is a weakly migratory element, although the content of the mobile form is quite high. The amount of mobile copper depends on many factors: chemical and mineralogical composition parent rock, soil solution pH, organic matter content, etc. The largest amount of copper in the soil is associated with iron oxides, manganese, iron and aluminum hydroxides, and, especially, with vermiculite montmorillonite. Humic and fulvic acids are able to form stable complexes with copper. At pH 7-8, the solubility of copper is the lowest.

MPC for copper in Russia is 55 mg/kg, APC for sandy and sandy loamy soils is 33 mg/kg.

Data on the toxicity of the element to plants are scarce. Currently, the main problem is the lack of copper in soils or its imbalance with cobalt. The main signs of copper deficiency for plants are a slowdown and then cessation of the formation of reproductive organs, the appearance of puny grain, empty-grained ears, and a decrease in resistance to adverse environmental factors. Wheat, oats, barley, alfalfa, red beets, onions and sunflowers are most sensitive to its deficiency.

Manganese It is widely distributed in soils, but is found there in smaller quantities compared to iron. Manganese is found in soil in several forms. The only forms available to plants are the exchangeable and water-soluble forms of manganese. The availability of soil manganese decreases with increasing pH (with decreasing soil acidity). Rarely, however, are soils depleted by leaching to such an extent that there is not enough available manganese for plant nutrition.

Depending on the type of soil, the content of manganese varies: chestnut 15.5 ± 2.0 mg/kg, serozem 22.0 ± 1.8 mg/kg, meadow 6.1 ± 0.6 mg/kg, zheltozem 4.7 ± 3.8 mg/kg, sandy 6.8 ± 0.7 mg/kg.

Manganese compounds are strong oxidizing agents. The maximum allowable concentration for chernozem soils is
1500 mg/kg soil.

The content of manganese in plant foods grown on meadow, yellow earth and sandy soils correlates with its content in these soils. The amount of manganese in the daily diet in these geochemical provinces is more than 2 times less daily requirement human and food ration of people living in the zones of chestnut and sierozem soils.



Heavy metals in soil

AT recent times in connection with the rapid development of industry, there is a significant increase in the level of heavy metals in the environment. The term "heavy metals" is applied to metals either with a density exceeding 5 g/cm 3 or with atomic number more than 20. Although, there is another point of view, according to which heavy metals include more than 40 chemical elements with atomic masses greater than 50 at. units Among the chemical elements, heavy metals are the most toxic and second only to pesticides in terms of their level of danger. At the same time, the following chemical elements are toxic: Co, Ni, Cu, Zn, Sn, As, Se, Te, Rb, Ag, Cd, Au, Hg, Pb, Sb, Bi, Pt.

Phytotoxicity of heavy metals depends on their chemical properties: valency, ionic radius and ability to complex formation. In most cases, according to the degree of toxicity, the elements are arranged in the sequence: Cu> Ni> Cd> Zn> Pb> Hg> Fe> Mo> Mn. However, this series may change somewhat due to the unequal precipitation of elements by the soil and the transfer to a state inaccessible to plants, growing conditions, and the physiological and genetic characteristics of the plants themselves. The transformation and migration of heavy metals occurs with direct and indirect influence complex formation reactions. When assessing pollution environment it is necessary to take into account the properties of the soil and, first of all, the granulometric composition, humus content and buffering. Buffering capacity is understood as the ability of soils to maintain the concentration of metals in the soil solution at a constant level.

In soils, heavy metals are present in two phases - solid and in soil solution. The form of existence of metals is determined by the reaction of the environment, chemical and material composition soil solution and, first of all, the content of organic matter. Elements - complexants that pollute the soil are concentrated mainly in its upper 10 cm layer. However, when low-buffer soil is acidified, a significant proportion of metals from the exchange-absorbed state passes into the soil solution. Strong migratory ability acidic environment possess cadmium, copper, nickel, cobalt. A decrease in pH by 1.8-2 units leads to an increase in the mobility of zinc by 3.8-5.4, cadmium - by 4-8, copper - by 2-3 times. .

Table 1 MPC (MAC) standards, background concentrations of chemical elements in soils (mg/kg)

	Hazard Class		AEC by soil groups
	Extractable with ammonium acetate buffer (рН=4.8)	Sandy, sandy	loamy, clayey
pH xl< 5,5	pH xl > 5.5

Thus, when entering the soil, heavy metals quickly interact with organic ligands to form complex compounds. So, at low concentrations in the soil (20-30 mg/kg), approximately 30% of lead is in the form of complexes with organic substances. The share of lead complex compounds increases with its concentration up to 400 mg/g, and then decreases. Metals are also sorbed (exchange or non-exchange) by precipitation of iron and manganese hydroxides, clay minerals, and soil organic matter. Metals available to plants and capable of leaching are found in the soil solution in the form of free ions, complexes, and chelates.

HM uptake by soil in more depends on the reaction of the medium and on which anions prevail in the soil solution. In an acidic environment, copper, lead and zinc are more sorbed, and in an alkaline environment, cadmium and cobalt are intensively absorbed. Copper preferentially binds to organic ligands and iron hydroxides.

Table 2 Mobility of trace elements in various soils depending on the pH of the soil solution

Soil-climatic factors often determine the direction and rate of migration and transformation of HMs in the soil. Thus, soil conditions and water regimes forest-steppe zone contribute to intensive vertical migration of HM along the soil profile, including the possible transfer of metals with water flow along cracks, root passages, etc. .

Nickel (Ni) - element of group VIII periodic system with atomic mass 58.71. Nickel, along with Mn, Fe, Co and Cu, belongs to the so-called transition metals, the compounds of which are highly biologically active. Due to the peculiarities of the structure of electron orbitals, the above metals, including nickel, have a well-pronounced ability to complex formation. Nickel is able to form stable complexes with, for example, cysteine ​​and citrate, as well as with many organic and inorganic ligands. The geochemical composition of parent rocks largely determines the nickel content in soils. The largest number Nickel is contained in soils formed from basic and ultrabasic rocks. According to some authors, the boundaries of excess and toxic levels nickel for most species vary from 10 to 100 mg/kg. The main mass of nickel is immovably fixed in the soil, and very weak migration in the colloidal state and in the composition of mechanical suspensions does not affect their distribution along the vertical profile and is quite uniform.

Lead (Pb). The chemistry of lead in soil is determined by a delicate balance of oppositely directed processes: sorption-desorption, dissolution-transition into solid state. Lead released into the soil with emissions is included in the cycle of physical, chemical and physico-chemical transformations. At first, the processes of mechanical displacement dominate (lead particles move along the surface and in the soil along cracks) and convective diffusion. Then, as solid-phase lead compounds dissolve, more complex physicochemical processes (in particular, ion diffusion processes) come into play, accompanied by the transformation of lead compounds that come with dust.

It has been established that lead migrates both vertically and horizontally, with the second process prevailing over the first. Over 3 years of observations on a forb meadow, lead dust deposited locally on the soil surface moved in a horizontal direction by 25-35 cm, while its penetration depth into the soil thickness was 10-15 cm. Important role play in lead migration biological factors: plant roots absorb metal ions; during the growing season, they move in the thickness of the soil; As plants die and decompose, lead is released into the surrounding soil mass.

It is known that the soil has the ability to bind (sorb) technogenic lead that has entered it. Sorption is believed to include several processes: complete exchange with the cations of the absorbing complex of soils (nonspecific adsorption) and a number of complexation reactions of lead with donors of soil components (specific adsorption). In soil, lead is associated mainly with organic matter, as well as with clay minerals, manganese oxides, iron and aluminum hydroxides. By binding lead, humus prevents its migration to adjacent environments and limits its entry into plants. Of the clay minerals, illites are characterized by a tendency to lead sorption. An increase in soil pH during liming leads to even greater binding of lead by the soil due to the formation of sparingly soluble compounds (hydroxides, carbonates, etc.).

Lead, which is present in the soil in mobile forms, is fixed with time by soil components and becomes inaccessible to plants. According to domestic researchers, lead is most strongly fixed in chernozem and peat-silt soils.

Cadmium (Cd) A feature of cadmium that distinguishes it from other HMs is that it is present in the soil solution mainly in the form of cations (Cd 2+), although in soil with a neutral reaction of the environment it can form sparingly soluble complexes with sulfates, phosphates or hydroxides.

According to available data, the concentration of cadmium in soil solutions of background soils ranges from 0.2 to 6 µg/l. In the centers of soil pollution, it increases to 300-400 µg/l. .

It is known that cadmium in soils is very mobile; able to move into large quantities from the solid phase to the liquid phase and vice versa (which makes it difficult to predict its entry into the plant). The mechanisms that regulate the concentration of cadmium in the soil solution are determined by the processes of sorption (by sorption we mean adsorption, precipitation, and complex formation). Cadmium is absorbed by the soil in smaller amounts than other HMs. To characterize the mobility of heavy metals in soil, the ratio of the concentrations of metals in the solid phase to that in the equilibrium solution is used. High values This ratio indicates that HMs are retained in the solid phase due to the sorption reaction, low - due to the fact that the metals are in solution, from where they can migrate to other media or enter into various reactions (geochemical or biological). It is known that the leading process in the binding of cadmium is adsorption by clays. Research recent years also showed an important role in this process hydroxyl groups, iron oxides and organic matter. At a low level of pollution and a neutral reaction of the medium, cadmium is adsorbed mainly by iron oxides. And in an acidic environment (pH = 5), organic matter begins to act as a powerful adsorbent. At a lower pH (pH=4), the adsorption functions go almost exclusively to organic matter. Mineral components in these processes cease to play any role.

It is known that cadmium is not only sorbed by the soil surface, but also fixed due to precipitation, coagulation, and interpacket absorption by clay minerals. It diffuses into soil particles through micropores and in other ways.

Cadmium is fixed in soils in different ways different type. So far, little is known about the competitive relationships of cadmium with other metals in the processes of sorption in the soil-absorbing complex. According to expert research Technical University Copenhagen (Denmark), in the presence of nickel, cobalt and zinc, the absorption of cadmium by the soil was suppressed. Other studies have shown that the processes of sorption of cadmium by soil decay in the presence of chloride ions. Saturation of the soil with Ca 2+ ions led to an increase in the sorption capacity of cadmium. Many bonds of cadmium with soil components turn out to be fragile; under certain conditions (for example, an acid reaction of the environment), it is released and goes back into solution.

The role of microorganisms in the process of cadmium dissolution and its transition to a mobile state is revealed. As a result of their vital activity, either water-soluble metal complexes are formed, or physical and chemical conditions are created that favor the transition of cadmium from the solid phase to the liquid.

The processes that occur with cadmium in the soil (sorption-desorption, transition into solution, etc.) are interconnected and interdependent; the flow of this metal into plants depends on their direction, intensity and depth. It is known that the value of sorption of cadmium by soil depends on the value of pH: the higher the pH of the soil, the more it absorbs cadmium. Thus, according to available data, in the pH range from 4 to 7.7, with an increase in pH per unit, the sorption capacity of soils with respect to cadmium increased approximately threefold.

Zinc (Zn). Zinc deficiency can manifest itself both on acidic, strongly podzolized light soils, and on carbonate, zinc-poor, and highly humus soils. Enhance the manifestation of zinc deficiency high doses phosphate fertilizers and strong plowing of the subsoil to the arable horizon.

The highest total zinc content in tundra (53-76 mg/kg) and chernozem (24-90 mg/kg) soils, the lowest - in sod-podzolic soils (20-67 mg/kg). Zinc deficiency is most often manifested in neutral and slightly alkaline calcareous soils. In acidic soils, zinc is more mobile and available to plants.

Zinc is present in the soil in the ionic form, where it is adsorbed by the cation exchange mechanism in an acidic or as a result of chemisorption in an alkaline medium. The Zn 2+ ion is the most mobile. The mobility of zinc in the soil is mainly affected by the pH value and the content of clay minerals. At pH<6 подвижность Zn 2+ возрастает, что приводит к его выщелачиванию. Попадая в межпакетные пространства кристаллической решетки монтмориллонита, ионы цинка теряют свою подвижность. Кроме того, цинк образует устойчивые формы с органическим веществом почвы, поэтому он накапливается в основном в горизонтах почв с высоким содержанием гумуса и в торфе .

PAGE_BREAK-- heavy metals, which characterizes a wide group of pollutants, has recently become widespread. 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 some cases, the definition of heavy metals includes elements that are brittle (for example, bismuth) or metalloids (for example, arsenic).

In the works devoted to the problems of environmental pollution and environmental monitoring, to date, to heavy metals include more than 40 metals of the periodic system D.I. Mendeleev with an atomic mass of more than 50 atomic units: V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Mo, Cd, Sn, Hg, Pb, Bi etc. 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, whose biological role is currently not clear), are actively involved in biological processes and are part of many enzymes. According to the classification of N. Reimers, metals with a density of more than 8 g/cm3 should be considered heavy. Thus, heavy metals are Pb, Cu, Zn, Ni, Cd, Co, Sb, Sn, Bi, Hg.

Formally defined heavy metals corresponds to a large number of elements. However, according to researchers involved in practical activities related to the organization of observations of the state and pollution of the environment, the compounds of these elements are far from equivalent as pollutants. Therefore, in many works there is a narrowing of the scope of the group of heavy metals, in accordance with the priority criteria, due to the direction and specifics of the work. So, in the already classic works of Yu.A. Israel in the list of chemicals to be determined in natural media at background stations in biosphere reserves, in the section heavy metals named Pb, Hg, Cd, As. On the other hand, according to the decision of the Task Force on Heavy Metal Emissions, which operates under the auspices of the United Nations Economic Commission for Europe and collects and analyzes information on pollutant emissions in European countries, only Zn, As, Se and Sb were assigned to heavy metals. According to the definition of N. Reimers, noble and rare metals stand apart from heavy metals, respectively, remain only Pb, Cu, Zn, Ni, Cd, Co, Sb, Sn, Bi, Hg. In applied work, heavy metals are most often added Pt, Ag, W, Fe, Au, Mn.

Metal ions are indispensable components of natural water bodies. Depending on the environmental conditions (pH, redox potential, the presence of ligands), they exist in different degrees of oxidation and are part of a variety of inorganic and organometallic compounds, which can be truly dissolved, colloidal-dispersed, or be part of mineral and organic suspensions.

The truly dissolved forms of metals, in turn, are very diverse, which is associated with the processes of hydrolysis, hydrolytic polymerization (formation of polynuclear hydroxo complexes), and complexation with various ligands. Accordingly, both the catalytic properties of metals and the availability for aquatic microorganisms depend on the forms of their existence in the aquatic ecosystem.

Many metals form fairly strong complexes with organics; these complexes are one of the most important forms of element migration in natural waters. Most organic complexes are formed by the chelate cycle and are stable. The complexes formed by soil acids with salts of iron, aluminum, titanium, uranium, vanadium, copper, molybdenum and other heavy metals are relatively well soluble in neutral, slightly acidic and slightly alkaline media. Therefore, organometallic complexes are capable of migrating in natural waters over very considerable distances. This is especially important for low-mineralized and, first of all, surface waters, in which the formation of other complexes is impossible.

To understand the factors that regulate the metal concentration in natural waters, their chemical reactivity, bioavailability and toxicity, it is necessary to know not only the total content, but also the proportion of free and bound metal forms.

The transition of metals in an aqueous medium to the metal complex form has three consequences:

1. There may be an increase in the total concentration of metal ions due to its transition into solution from bottom sediments;

2. The membrane permeability of complex ions can differ significantly from the permeability of hydrated ions;

3. The toxicity of the metal as a result of complexation can change greatly.

So, chelate forms Cu, Cd, Hg less toxic than free ions. To understand the factors that regulate the metal concentration in natural waters, their chemical reactivity, bioavailability and toxicity, it is necessary to know not only the total content, but also the proportion of bound and free forms.

The sources of water pollution with heavy metals are wastewater from galvanizing shops, mining, ferrous and non-ferrous metallurgy, and machine-building plants. Heavy metals are found in fertilizers and pesticides and can enter water bodies along with runoff from agricultural land.

An increase in the concentration of heavy metals in natural waters is often associated with other types of pollution, such as acidification. The precipitation of acid precipitation contributes to a decrease in the pH value and the transition of metals from a state adsorbed on mineral and organic substances to a free state.

First of all, of interest are those metals that pollute the atmosphere the most due to their use in significant volumes in production activities and, as a result of accumulation in the external environment, pose a serious danger in terms of their biological activity and toxic properties. These include lead, mercury, cadmium, zinc, bismuth, cobalt, nickel, copper, tin, antimony, vanadium, manganese, chromium, molybdenum and arsenic.
Biogeochemical properties of heavy metals

H - high, Y - moderate, H - low

Vanadium.

Vanadium is predominantly in a dispersed state and is found in iron ores, oil, asphalt, bitumen, oil shale, coal, etc. One of the main sources of vanadium pollution of natural waters is oil and its products.

It occurs in natural waters in very low concentrations: in river water 0.2 - 4.5 µg/dm3, in sea water - an average of 2 µg/dm3

In water it forms stable anionic complexes (V4O12)4- and (V10O26)6-. In the migration of vanadium, the role of its dissolved complex compounds with organic substances, especially with humic acids, is essential.

Elevated concentrations of vanadium are harmful to human health. MPCv of vanadium is 0.1 mg/dm3 (the limiting indicator of harmfulness is sanitary-toxicological), MPCvr is 0.001 mg/dm3.

The natural sources of bismuth entering natural waters are the processes of leaching of bismuth-containing minerals. The source of entry into natural waters can also be wastewater from pharmaceutical and perfume industries, some glass industry enterprises.

It is found in unpolluted surface waters in submicrogram concentrations. The highest concentration was found in groundwater and is 20 µg/dm3, in marine waters - 0.02 µg/dm3. MPCv is 0.1 mg/dm3

The main sources of iron compounds in surface waters are the processes of chemical weathering of rocks, accompanied by their mechanical destruction and dissolution. In the process of interaction with mineral and organic substances contained in natural waters, a complex complex of iron compounds is formed, which are in water in a dissolved, colloidal and suspended state. Significant amounts of iron come with underground runoff and with wastewater from enterprises of the metallurgical, metalworking, textile, paint and varnish industries and with agricultural effluents.

Phase equilibria depend on the chemical composition of water, pH, Eh, and, to some extent, temperature. In routine analysis weighted form emit particles with a size of more than 0.45 microns. It is predominantly iron-bearing minerals, iron oxide hydrate and iron compounds adsorbed on suspensions. Truly dissolved and colloidal form are usually considered together. Dissolved iron represented by compounds in ionic form, in the form of a hydroxocomplex and complexes with dissolved inorganic and organic substances of natural waters. In the ionic form, mainly Fe(II) migrates, and Fe(III) in the absence of complexing substances cannot be in a significant amount in a dissolved state.

Iron is found mainly in waters with low Eh values.

As a result of chemical and biochemical (with the participation of iron bacteria) oxidation, Fe(II) passes into Fe(III), which, upon hydrolysis, precipitates in the form of Fe(OH)3. Both Fe(II) and Fe(III) tend to form hydroxo complexes of the type +, 4+, +, 3+, - and others that coexist in solution at different concentrations depending on pH and generally determine the state of the iron-hydroxyl system. The main form of occurrence of Fe(III) in surface waters is its complex compounds with dissolved inorganic and organic compounds, mainly humic substances. At pH = 8.0, the main form is Fe(OH)3. The colloidal form of iron is the least studied; it is iron oxide hydrate Fe(OH)3 and complexes with organic substances.

The content of iron in the surface waters of the land is tenths of a milligram, near the swamps - a few milligrams. An increased content of iron is observed in swamp waters, in which it is found in the form of complexes with salts of humic acids - humates. The highest concentrations of iron (up to several tens and hundreds of milligrams per 1 dm3) are observed in groundwater with low pH values.

Being a biologically active element, iron to a certain extent affects the intensity of phytoplankton development and the qualitative composition of the microflora in the reservoir.

Iron concentrations are subject to marked seasonal fluctuations. Usually, in reservoirs with high biological productivity, during the period of summer and winter stagnation, an increase in the concentration of iron in the bottom layers of water is noticeable. The autumn-spring mixing of water masses (homothermia) is accompanied by the oxidation of Fe(II) to Fe(III) and the precipitation of the latter in the form of Fe(OH)3.

It enters natural waters during the leaching of soils, polymetallic and copper ores, as a result of the decomposition of aquatic organisms capable of accumulating it. Cadmium compounds are carried into surface water with wastewater from lead-zinc plants, ore-dressing plants, a number of chemical enterprises (sulfuric acid production), galvanic production, and also with mine waters. The decrease in the concentration of dissolved cadmium compounds occurs due to the processes of sorption, precipitation of cadmium hydroxide and carbonate and their consumption by aquatic organisms.

Dissolved forms of cadmium in natural waters are mainly mineral and organo-mineral complexes. The main suspended form of cadmium is its adsorbed compounds. A significant part of cadmium can migrate within the cells of aquatic organisms.

In river uncontaminated and slightly polluted waters, cadmium is contained in submicrogram concentrations; in polluted and waste waters, the concentration of cadmium can reach tens of micrograms per 1 dm3.

Cadmium compounds play an important role in the life of animals and humans. It is toxic in high concentrations, especially in combination with other toxic substances.

MPCv is 0.001 mg/dm3, MPCvr is 0.0005 mg/dm3 (the limiting sign of harmfulness is toxicological).

Cobalt compounds enter natural waters as a result of their leaching from copper pyrite and other ores, from soils during the decomposition of organisms and plants, as well as with wastewater from metallurgical, metalworking and chemical plants. Some amounts of cobalt come from soils as a result of the decomposition of plant and animal organisms.

Cobalt compounds in natural waters are in a dissolved and suspended state, the quantitative ratio between which is determined by the chemical composition of water, temperature and pH values. Dissolved forms are represented mainly by complex compounds, incl. with organic matter in natural waters. Divalent cobalt compounds are most characteristic of surface waters. In the presence of oxidizing agents, trivalent cobalt can exist in appreciable concentrations.

Cobalt is one of the biologically active elements and is always found in the body of animals and plants. Insufficient content of cobalt in plants is associated with its insufficient content in soils, which contributes to the development of anemia in animals (taiga-forest non-chernozem zone). As part of vitamin B12, cobalt has a very active effect on the intake of nitrogenous substances, an increase in the content of chlorophyll and ascorbic acid, activates biosynthesis and increases the content of protein nitrogen in plants. However, elevated concentrations of cobalt compounds are toxic.

In unpolluted and slightly polluted river waters, its content varies from tenths to thousandths of a milligram per 1 dm3, the average content in sea water is 0.5 μg/dm3. MPCv is 0.1 mg/dm3, MPCv is 0.01 mg/dm3.

Manganese

Manganese enters surface waters as a result of leaching of ferromanganese ores and other minerals containing manganese (pyrolusite, psilomelane, brownite, manganite, black ocher). Significant amounts of manganese come from the decomposition of aquatic animals and plant organisms, especially blue-green, diatoms and higher aquatic plants. Manganese compounds are discharged into reservoirs with wastewater from manganese processing plants, metallurgical plants, chemical industry enterprises and mine waters.

A decrease in the concentration of manganese ions in natural waters occurs as a result of the oxidation of Mn(II) to MnO2 and other high-valent oxides that precipitate. The main parameters that determine the oxidation reaction are the concentration of dissolved oxygen, pH value and temperature. The concentration of dissolved manganese compounds decreases due to their utilization by algae.

The main form of migration of manganese compounds in surface waters is suspensions, the composition of which is determined in turn by the composition of rocks drained by waters, as well as colloidal hydroxides of heavy metals and sorbed manganese compounds. Of essential importance in the migration of manganese in dissolved and colloidal forms are organic substances and the processes of complex formation of manganese with inorganic and organic ligands. Mn(II) forms soluble complexes with bicarbonates and sulfates. Complexes of manganese with a chloride ion are rare. Complex compounds of Mn(II) with organic substances are usually less stable than with other transition metals. These include compounds with amines, organic acids, amino acids and humic substances. Mn(III) in high concentrations can be in a dissolved state only in the presence of strong complexing agents; Mn(YII) does not occur in natural waters.

In river waters, the manganese content usually ranges from 1 to 160 µg/dm3, the average content in sea waters is 2 µg/dm3, in underground waters - n.102 - n.103 µg/dm3.

The concentration of manganese in surface waters is subject to seasonal fluctuations.

The factors determining changes in manganese concentrations are the ratio between surface and underground runoff, the intensity of its consumption during photosynthesis, the decomposition of phytoplankton, microorganisms and higher aquatic vegetation, as well as the processes of its deposition on the bottom of water bodies.

The role of manganese in the life of higher plants and algae in water bodies is very large. Manganese contributes to the utilization of CO2 by plants, which increases the intensity of photosynthesis, participates in the processes of nitrate reduction and nitrogen assimilation by plants. Manganese promotes the transition of active Fe(II) to Fe(III), which protects the cell from poisoning, accelerates the growth of organisms, etc. The important ecological and physiological role of manganese necessitates the study and distribution of manganese in natural waters.

For water bodies for sanitary use, MPCv (according to the manganese ion) is set equal to 0.1 mg/dm3.

Below are maps of the distribution of average concentrations of metals: manganese, copper, nickel and lead, built according to observational data for 1989 - 1993. in 123 cities. The use of later data is considered inappropriate, since due to the reduction in production, the concentrations of suspended solids and, accordingly, metals have significantly decreased.

Impact on health. Many metals are a constituent of dust and have a significant impact on health.

Manganese enters the atmosphere from emissions from ferrous metallurgy enterprises (60% of all manganese emissions), mechanical engineering and metalworking (23%), non-ferrous metallurgy (9%), numerous small sources, for example, from welding.

High concentrations of manganese lead to the appearance of neurotoxic effects, progressive damage to the central nervous system, pneumonia.
The highest concentrations of manganese (0.57 - 0.66 µg/m3) are observed in large centers of metallurgy: in Lipetsk and Cherepovets, as well as in Magadan. Most of the cities with high concentrations of Mn (0.23 - 0.69 µg/m3) are concentrated on the Kola Peninsula: Zapolyarny, Kandalaksha, Monchegorsk, Olenegorsk (see map).

For 1991 - 1994 manganese emissions from industrial sources decreased by 62%, average concentrations - by 48%.

Copper is one of the most important trace elements. The physiological activity of copper is associated mainly with its inclusion in the composition of the active centers of redox enzymes. Insufficient copper content in soils adversely affects the synthesis of proteins, fats and vitamins and contributes to the infertility of plant organisms. Copper is involved in the process of photosynthesis and affects the absorption of nitrogen by plants. At the same time, excessive concentrations of copper have an adverse effect on plant and animal organisms.

Cu(II) compounds are the most common in natural waters. Of the Cu(I) compounds, Cu2O, Cu2S, and CuCl, which are sparingly soluble in water, are the most common. In the presence of ligands in an aqueous medium, along with the equilibrium of hydroxide dissociation, it is necessary to take into account the formation of various complex forms that are in equilibrium with metal aqua ions.

The main source of copper entering natural waters is wastewater from chemical and metallurgical industries, mine waters, and aldehyde reagents used to kill algae. Copper can form as a result of corrosion of copper pipes and other structures used in water systems. In groundwater, the copper content is due to the interaction of water with rocks containing it (chalcopyrite, chalcocite, covellite, bornite, malachite, azurite, chrysacolla, brotantine).

The maximum permissible concentration of copper in the water of reservoirs for sanitary and household water use is 0.1 mg/dm3 (the limiting sign of harmfulness is general sanitary), in the water of fishery reservoirs it is 0.001 mg/dm3.

City

Norilsk

Monchegorsk

Krasnouralsk

Kolchugino

Zapolyarny

Emissions М (thousand tons/year) of copper oxide and average annual concentrations q (µg/m3) of copper.

Copper enters the air with emissions from metallurgical industries. In particulate matter emissions, it is contained mainly in the form of compounds, mainly copper oxide.

Non-ferrous metallurgy enterprises account for 98.7% of all anthropogenic emissions of this metal, of which 71% are carried out by enterprises of the Norilsk Nickel concern located in Zapolyarny and Nikel, Monchegorsk and Norilsk, and about 25% of copper emissions are carried out in Revda, Krasnouralsk , Kolchugino and others.

High concentrations of copper lead to intoxication, anemia and hepatitis.

As can be seen from the map, the highest concentrations of copper are noted in the cities of Lipetsk and Rudnaya Pristan. Copper concentrations were also increased in the cities of the Kola Peninsula, in Zapolyarny, Monchegorsk, Nikel, Olenegorsk, and also in Norilsk.

Emissions of copper from industrial sources decreased by 34%, average concentrations - by 42%.

Molybdenum

Molybdenum compounds enter surface waters as a result of their leaching from exogenous minerals containing molybdenum. Molybdenum also enters water bodies with wastewater from processing plants and non-ferrous metallurgy enterprises. The decrease in the concentrations of molybdenum compounds occurs as a result of the precipitation of sparingly soluble compounds, the processes of adsorption by mineral suspensions and consumption by plant aquatic organisms.

Molybdenum in surface waters is mainly in the form MoO42-. It is highly probable that it exists in the form of organomineral complexes. The possibility of some accumulation in the colloidal state follows from the fact that the products of molybdenite oxidation are loose finely dispersed substances.

In river waters, molybdenum is found in concentrations from 2.1 to 10.6 µg/dm3. Sea water contains an average of 10 µg/dm3 of molybdenum.

In small quantities, molybdenum is necessary for the normal development of plant and animal organisms. Molybdenum is part of the xanthine oxidase enzyme. With a deficiency of molybdenum, the enzyme is formed in insufficient quantities, which causes negative reactions in the body. In high concentrations, molybdenum is harmful. With an excess of molybdenum, metabolism is disturbed.

The maximum permissible concentration of molybdenum in water bodies for sanitary use is 0.25 mg/dm3.

Arsenic enters natural waters from mineral springs, areas of arsenic mineralization (arsenic pyrites, realgar, orpiment), as well as from zones of oxidation of rocks of polymetallic, copper-cobalt and tungsten types. A certain amount of arsenic comes from soils, as well as from the decomposition of plant and animal organisms. Consumption of arsenic by aquatic organisms is one of the reasons for the decrease in its concentration in water, which is most clearly manifested during the period of intensive development of plankton.

Significant amounts of arsenic enter water bodies with wastewater from processing plants, waste from the production of dyes, tanneries and pesticide factories, as well as from agricultural lands where pesticides are used.

In natural waters, arsenic compounds are in a dissolved and suspended state, the ratio between which is determined by the chemical composition of water and pH values. In dissolved form, arsenic occurs in tri- and pentavalent forms, mainly as anions.

In unpolluted river waters, arsenic is usually found in microgram concentrations. In mineral waters, its concentration can reach several milligrams per 1 dm3, in sea waters it contains on average 3 µg/dm3, in underground waters it occurs in concentrations of n.105 µg/dm3. Arsenic compounds in high concentrations are toxic to the body of animals and humans: they inhibit oxidative processes, inhibit the supply of oxygen to organs and tissues.

MPCv for arsenic is 0.05 mg/dm3 (the limiting indicator of harmfulness is sanitary-toxicological) and MPCv is 0.05 mg/dm3.

The presence of nickel in natural waters is due to the composition of the rocks through which water passes: it is found in places of deposits of sulfide copper-nickel ores and iron-nickel ores. It enters the water from soils and from plant and animal organisms during their decay. An increased content of nickel compared to other types of algae was found in blue-green algae. Nickel compounds also enter water bodies with wastewater from nickel plating shops, synthetic rubber plants, and nickel enrichment plants. Huge nickel emissions accompany the burning of fossil fuels.

Its concentration can decrease as a result of the precipitation of compounds such as cyanides, sulfides, carbonates or hydroxides (with increasing pH values), due to its consumption by aquatic organisms and adsorption processes.

In surface waters, nickel compounds are in dissolved, suspended, and colloidal states, the quantitative ratio between which depends on the water composition, temperature, and pH values. Sorbents of nickel compounds can be iron hydroxide, organic substances, highly dispersed calcium carbonate, clays. Dissolved forms are mainly complex ions, most often with amino acids, humic and fulvic acids, and also in the form of a strong cyanide complex. Nickel compounds are the most common in natural waters, in which it is in the +2 oxidation state. Ni3+ compounds are usually formed in an alkaline medium.

Nickel compounds play an important role in hematopoietic processes, being catalysts. Its increased content has a specific effect on the cardiovascular system. Nickel is one of the carcinogenic elements. It can cause respiratory diseases. It is believed that free nickel ions (Ni2+) are about 2 times more toxic than its complex compounds.

In unpolluted and slightly polluted river waters, the nickel concentration usually ranges from 0.8 to 10 μg/dm3; in polluted it is several tens of micrograms per 1 dm3. The average concentration of nickel in sea water is 2 µg/dm3, in groundwater - n.103 µg/dm3. In underground waters washing nickel-containing rocks, nickel concentration sometimes increases up to 20 mg/dm3.

Nickel enters the atmosphere from non-ferrous metallurgy enterprises, which account for 97% of all nickel emissions, of which 89% come from enterprises of the Norilsk Nickel concern located in Zapolyarny and Nikel, Monchegorsk and Norilsk.

The increased content of nickel in the environment leads to the appearance of endemic diseases, bronchial cancer. Nickel compounds belong to the 1st group of carcinogens.
The map shows several points with high average concentrations of nickel in the locations of the Norilsk Nickel concern: Apatity, Kandalaksha, Monchegorsk, Olenegorsk.

Nickel emissions from industrial enterprises decreased by 28%, average concentrations - by 35%.

Emissions М (thousand tons/year) and average annual concentrations q (µg/m3) of nickel.

It enters natural waters as a result of leaching of tin-containing minerals (cassiterite, stannin), as well as with wastewater from various industries (fabric dyeing, synthesis of organic dyes, production of alloys with the addition of tin, etc.).

The toxic effect of tin is small.

Tin is found in unpolluted surface waters in submicrogram concentrations. In groundwater, its concentration reaches a few micrograms per 1 dm3. MPCv is 2 mg/dm3.

Mercury compounds can enter surface waters as a result of leaching of rocks in the area of ​​mercury deposits (cinnabar, metacinnabarite, livingstone), in the process of decomposition of aquatic organisms that accumulate mercury. Significant amounts enter water bodies with wastewater from enterprises producing dyes, pesticides, pharmaceuticals, and some explosives. Coal-fired thermal power plants emit significant amounts of mercury compounds into the atmosphere, which, as a result of wet and dry fallout, enter water bodies.

The decrease in the concentration of dissolved mercury compounds occurs as a result of their extraction by many marine and freshwater organisms, which have the ability to accumulate it in concentrations many times higher than its content in water, as well as adsorption processes by suspended solids and bottom sediments.

In surface waters, mercury compounds are in dissolved and suspended state. The ratio between them depends on the chemical composition of water and pH values. Suspended mercury is sorbed mercury compounds. Dissolved forms are undissociated molecules, complex organic and mineral compounds. In the water of water bodies, mercury can be in the form of methylmercury compounds.

Mercury compounds are highly toxic, they affect the human nervous system, cause changes in the mucous membrane, impaired motor function and secretion of the gastrointestinal tract, changes in the blood, etc. Bacterial methylation processes are aimed at the formation of methylmercury compounds, which are many times more toxic than mineral salts mercury. Methylmercury compounds accumulate in fish and can enter the human body.

MPCv of mercury is 0.0005 mg/dm3 (the limiting sign of harmfulness is sanitary-toxicological), MPCv is 0.0001 mg/dm3.

Natural sources of lead in surface waters are the processes of dissolution of endogenous (galena) and exogenous (anglesite, cerussite, etc.) minerals. A significant increase in the content of lead in the environment (including in surface waters) is associated with the combustion of coal, the use of tetraethyl lead as an antiknock agent in motor fuel, with the removal into water bodies with wastewater from ore processing plants, some metallurgical plants, chemical industries, mines, etc. Significant factors in lowering the concentration of lead in water are its adsorption by suspended solids and sedimentation with them into bottom sediments. Among other metals, lead is extracted and accumulated by hydrobionts.

Lead is found in natural waters in a dissolved and suspended (sorbed) state. In dissolved form, it occurs in the form of mineral and organomineral complexes, as well as simple ions, in insoluble form - mainly in the form of sulfides, sulfates and carbonates.

In river waters, the lead concentration ranges from tenths to units of micrograms per 1 dm3. Even in the water of water bodies adjacent to areas of polymetallic ores, its concentration rarely reaches tens of milligrams per 1 dm3. Only in chloride thermal waters the concentration of lead sometimes reaches several milligrams per 1 dm3.

The limiting indicator of harmfulness of lead is sanitary-toxicological. MPCv of lead is 0.03 mg/dm3, MPCv is 0.1 mg/dm3.

Lead is contained in emissions from metallurgy, metalworking, electrical engineering, petrochemistry and motor transport enterprises.

The impact of lead on health occurs through the inhalation of air containing lead, and the intake of lead with food, water, and dust particles. Lead accumulates in the body, in bones and surface tissues. Lead affects the kidneys, liver, nervous system and blood-forming organs. The elderly and children are especially sensitive to even low doses of lead.

Emissions M (thousand tons/year) and average annual concentrations q (µg/m3) of lead.

In seven years, lead emissions from industrial sources have decreased by 60% due to production cuts and the closure of many enterprises. The sharp decline in industrial emissions is not accompanied by a decrease in vehicle emissions. Average lead concentrations decreased by only 41%. The difference in abatement rates and lead concentrations can be explained by the underestimation of vehicle emissions in previous years; Currently, the number of cars and the intensity of their movement has increased.

Tetraethyl lead

It enters natural waters due to the use as an antiknock agent in the motor fuel of water vehicles, as well as with surface runoff from urban areas.

This substance is characterized by high toxicity, has cumulative properties.

The sources of silver entering surface waters are groundwater and wastewater from mines, processing plants, and photographic enterprises. The increased content of silver is associated with the use of bactericidal and algicidal preparations.

In wastewater, silver can be present in dissolved and suspended form, mostly in the form of halide salts.

In unpolluted surface waters, silver is found in submicrogram concentrations. In groundwater, the concentration of silver varies from a few to tens of micrograms per 1 dm3, in sea water, on average, 0.3 μg/dm3.

Silver ions are capable of destroying bacteria and sterilize water even in small concentrations (the lower limit of the bactericidal action of silver ions is 2.10-11 mol/dm3). The role of silver in the body of animals and humans has not been studied enough.

MPCv of silver is 0.05 mg/dm3.

Antimony enters surface waters through the leaching of antimony minerals (stibnite, senarmontite, valentinite, servingite, stibiocanite) and with wastewater from rubber, glass, dyeing, and match enterprises.

In natural waters, antimony compounds are in a dissolved and suspended state. Under the redox conditions characteristic of surface waters, both trivalent and pentavalent antimony can exist.

In unpolluted surface waters, antimony is found in submicrogram concentrations, in sea water its concentration reaches 0.5 µg/dm3, in groundwater - 10 µg/dm3. MPCv of antimony is 0.05 mg/dm3 (the limiting indicator of harmfulness is sanitary-toxicological), MPCv is 0.01 mg/dm3.

Tri- and hexavalent chromium compounds enter surface waters as a result of leaching from rocks (chromite, crocoite, uvarovite, etc.). Some quantities come from the decomposition of organisms and plants, from soils. Significant quantities can enter water bodies with wastewater from electroplating shops, dyeing shops of textile enterprises, tanneries and chemical industries. A decrease in the concentration of chromium ions can be observed as a result of their consumption by aquatic organisms and adsorption processes.

In surface waters, chromium compounds are in dissolved and suspended states, the ratio between which depends on the composition of the water, temperature, pH of the solution. Suspended chromium compounds are mainly sorbed chromium compounds. Sorbents can be clays, iron hydroxide, highly dispersed settling calcium carbonate, plant and animal residues. In dissolved form, chromium can be in the form of chromates and bichromates. Under aerobic conditions, Cr(VI) transforms into Cr(III), whose salts in neutral and alkaline media are hydrolyzed with the release of hydroxide.

In unpolluted and slightly polluted river waters, the chromium content ranges from several tenths of a microgram per liter to several micrograms per liter, in polluted water bodies it reaches several tens and hundreds of micrograms per liter. The average concentration in sea waters is 0.05 µg/dm3, in groundwater - usually within n.10 - n.102 µg/dm3.

Cr(VI) and Cr(III) compounds in increased amounts have carcinogenic properties. Cr(VI) compounds are more dangerous.

It enters natural waters as a result of natural processes of destruction and dissolution of rocks and minerals (sphalerite, zincite, goslarite, smithsonite, calamine), as well as with wastewater from ore processing plants and electroplating shops, production of parchment paper, mineral paints, viscose fiber and others

In water, it exists mainly in ionic form or in the form of its mineral and organic complexes. Sometimes it occurs in insoluble forms: in the form of hydroxide, carbonate, sulfide, etc.

In river waters, the concentration of zinc usually ranges from 3 to 120 µg/dm3, in marine waters - from 1.5 to 10 µg/dm3. The content in ore and especially in mine waters with low pH values ​​can be significant.

Zinc is one of the active trace elements that affect the growth and normal development of organisms. At the same time, many zinc compounds are toxic, primarily its sulfate and chloride.

MPCv Zn2+ is 1 mg/dm3 (limiting indicator of harmfulness - organoleptic), MPCvr Zn2+ - 0.01 mg/dm3 (limiting sign of harmfulness - toxicological).

Heavy metals are already in second place in terms of danger, yielding to pesticides and well ahead of such well-known pollutants as carbon dioxide and sulfur, but in the forecast they should become the most dangerous, more dangerous than nuclear power plant waste and solid waste. Pollution with heavy metals is associated with their widespread use in industrial production, coupled with weak cleaning systems, as a result of which heavy metals enter the environment, including the soil, polluting and poisoning it.

Heavy metals are among the priority pollutants, monitoring of which is mandatory in all environments. In various scientific and applied works, the authors interpret the meaning of the concept of "heavy metals" in different ways. In some cases, the definition of heavy metals includes elements that are brittle (for example, bismuth) or metalloids (for example, arsenic).

Soil is the main medium into which heavy metals 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. Heavy metals are assimilated from the soil by plants, which then get into the food of more highly organized animals.
continuation
--PAGE_BREAK-- 3.3. lead intoxication
Currently, lead occupies the first place among the causes of industrial poisoning. This is due to its wide application in various industries. Lead ore workers are exposed to lead in lead smelters, in the production of batteries, in soldering, in printing houses, in the manufacture of crystal glass or ceramic products, leaded gasoline, lead paints, etc. Lead pollution of atmospheric air, soil and water in the vicinity of such industries, as well as near major highways, creates a threat of lead poisoning of the population living in these areas, and, above all, children, who are more sensitive to the effects of heavy metals.
It should be noted with regret that in Russia there is no state policy on the legal, regulatory and economic regulation of the impact of lead on the environment and public health, on reducing emissions (discharges, wastes) of lead and its compounds into the environment, and on the complete cessation of the production of lead-containing gasoline.

Due to the extremely unsatisfactory educational work to explain to the population the degree of danger of heavy metal exposure to the human body, in Russia the number of contingents with occupational contact with lead is not decreasing, but is gradually increasing. Cases of chronic lead intoxication have been recorded in 14 industries in Russia. The leading industries are the electrical industry (production of batteries), instrumentation, printing and non-ferrous metallurgy, in which intoxication is caused by an excess of the maximum permissible concentration (MAC) of lead in the air of the working area by 20 or more times.

A significant source of lead is automotive exhaust, as half of Russia still uses leaded gasoline. However, metallurgical plants, in particular copper smelters, remain the main source of environmental pollution. And there are leaders here. On the territory of the Sverdlovsk region there are 3 largest sources of lead emissions in the country: in the cities of Krasnouralsk, Kirovograd and Revda.

The chimneys of the Krasnouralsk copper smelter, built back in the years of Stalinist industrialization and using equipment from 1932, annually spewing 150-170 tons of lead into the city of 34,000, covering everything with lead dust.

The concentration of lead in the soil of Krasnouralsk varies from 42.9 to 790.8 mg/kg, with the maximum allowable concentration MPC=130 microns/kg. Water samples in the water supply of the neighboring village. Oktyabrsky, fed by an underground water source, recorded an excess of MPC up to two times.

Lead pollution has an impact on human health. Lead exposure disrupts the female and male reproductive systems. For women of pregnant and childbearing age, elevated levels of lead in the blood pose a particular danger, since lead disrupts menstrual function, more often there are premature births, miscarriages and fetal death due to the penetration of lead through the placental barrier. Newborns have a high mortality rate.

Lead poisoning is extremely dangerous for young children - it affects the development of the brain and nervous system. Testing of 165 Krasnouralsk children from 4 years of age revealed a significant mental retardation in 75.7%, and 6.8% of the children examined were found to have mental retardation, including mental retardation.

Preschool children are most susceptible to the harmful effects of lead, as their nervous systems are still in development. Even at low doses, lead poisoning causes a decrease in intellectual development, attention and ability to concentrate, a lag in reading, leads to the development of aggressiveness, hyperactivity and other problems in the child's behavior. These developmental abnormalities can be long-term and irreversible. Low birth weight, stunting, and hearing loss are also the result of lead poisoning. High doses of intoxication lead to mental retardation, coma, convulsions and death.

A white paper published by Russian experts reports that lead pollution covers the entire country and is one of the many environmental disasters in the former Soviet Union that have come to light in recent years. Most of the territory of Russia is experiencing a load from lead deposition that exceeds the critical value for the normal functioning of the ecosystem. In dozens of cities, there is an excess of lead concentrations in the air and soil above the values ​​corresponding to the MPC.

The highest level of air pollution with lead, exceeding the MPC, was observed in the cities of Komsomolsk-on-Amur, Tobolsk, Tyumen, Karabash, Vladimir, Vladivostok.

The maximum loads of lead deposition leading to the degradation of terrestrial ecosystems are observed in the Moscow, Vladimir, Nizhny Novgorod, Ryazan, Tula, Rostov and Leningrad regions.

Stationary sources are responsible for the discharge of more than 50 tons of lead in the form of various compounds into water bodies. At the same time, 7 battery factories dump 35 tons of lead annually through the sewer system. An analysis of the distribution of lead discharges into water bodies on the territory of Russia shows that Leningrad, Yaroslavl, Perm, Samara, Penza and Oryol regions are leaders in this type of load.

The country needs urgent measures to reduce lead pollution, but so far Russia's economic crisis overshadows environmental problems. In a prolonged industrial depression, Russia lacks the funds to clean up past pollution, but if the economy starts to recover and factories return to work, pollution could only get worse.
10 most polluted cities of the former USSR

(Metals are listed in descending order of priority level for a given city)

4. Soil hygiene. Waste disposal.
The soil in cities and other settlements and their environs has long been different from the natural, biologically valuable soil, which plays an important role in maintaining the ecological balance. The soil in cities is subject to the same harmful effects as the city air and hydrosphere, so its significant degradation occurs everywhere. Soil hygiene is not given sufficient attention, although its importance as one of the main components of the biosphere (air, water, soil) and a biological environmental factor is even more significant than water, since the amount of the latter (primarily the quality of groundwater) is determined by the state of the soil, and it is impossible to separate these factors from each other. The soil has the ability of biological self-purification: in the soil there is a splitting of the waste that has fallen into it and their mineralization; in the end, the soil compensates for the lost minerals at their expense.

If, as a result of soil overload, any of the components of its mineralizing capacity is lost, this will inevitably lead to a violation of the self-purification mechanism and to complete degradation of the soil. And, on the contrary, the creation of optimal conditions for self-purification of the soil contributes to the preservation of the ecological balance and conditions for the existence of all living organisms, including humans.

Therefore, the problem of neutralizing waste that has a harmful biological effect is not limited to the issue of their export; it is a more complex hygienic problem, since the soil is the link between water, air and man.
4.1.
The role of soil in metabolism

The biological relationship between soil and man is carried out mainly through metabolism. The soil is, as it were, a supplier of minerals necessary for the metabolic cycle, for the growth of plants consumed by humans and herbivores, eaten in turn by humans and carnivores. Thus, the soil provides food for many representatives of the plant and animal world.

Consequently, the deterioration of soil quality, the decrease in its biological value, its ability to self-cleanse causes a biological chain reaction, which, in the event of prolonged harmful effects, can lead to a variety of health disorders among the population. Moreover, if mineralization processes slow down, nitrates, nitrogen, phosphorus, potassium, etc., formed during the decay of substances, can enter groundwater used for drinking purposes and cause serious diseases (for example, nitrates can cause methemoglobinemia, primarily in infant).

Consumption of water from soil poor in iodine can cause endemic goiter, etc.
4.2.
Ecological relationship between soil and water and liquid waste (wastewater)

A person extracts from the soil the water necessary to maintain metabolic processes and life itself. The quality of water depends on the condition of the soil; it always reflects the biological state of a given soil.

This applies in particular to groundwater, the biological value of which is essentially determined by the properties of soils and soil, the ability of the latter to self-purify, its filtration capacity, the composition of its macroflora, microfauna, etc.

The direct influence of the soil on surface water is already less significant, it is associated mainly with precipitation. For example, after heavy rains, various pollutants are washed out of the soil into open water bodies (rivers, lakes), including artificial fertilizers (nitrogen, phosphate), pesticides, herbicides; in areas of karst, fractured deposits, pollutants can penetrate through cracks into deep The groundwater.

Inadequate wastewater treatment can also cause harmful biological effects on the soil and eventually lead to soil degradation. Therefore, soil protection in settlements is one of the main requirements for environmental protection in general.
4.3.
Soil load limits for solid waste (household and street waste, industrial waste, dry sludge from sewage sedimentation, radioactive substances, etc.)

The problem is exacerbated by the fact that, as a result of the generation of more and more solid waste in cities, the soil in their vicinity is subjected to increasing pressure. Soil properties and composition are deteriorating at an ever faster pace.

Of the 64.3 million tons of paper produced in the USA, 49.1 million tons end up in waste (out of this amount, 26 million tons are supplied by the household, and 23.1 million tons by the trading network).

In connection with the foregoing, the removal and final disposal of solid waste is a very significant, more difficult to implement hygienic problem in the context of increasing urbanization.

Final disposal of solid waste in contaminated soil is possible. However, due to the constantly deteriorating self-cleaning capacity of urban soil, the final disposal of waste buried in the ground is impossible.

A person could successfully use the biochemical processes occurring in the soil, its neutralizing and disinfecting ability to neutralize solid waste, but urban soil, as a result of centuries of human habitation and activity in cities, has long become unsuitable for this purpose.

The mechanisms of self-purification, mineralization occurring in the soil, the role of the bacteria and enzymes involved in them, as well as the intermediate and final products of the decomposition of substances are well known. Currently, research is aimed at identifying the factors that ensure the biological balance of the natural soil, as well as clarifying the question of how much solid waste (and what composition) can lead to a violation of the biological balance of the soil.
The amount of household waste (garbage) per inhabitant of some large cities of the world

It should be noted that the hygienic condition of the soil in cities as a result of its overload is rapidly deteriorating, although the ability of the soil to self-purify is the main hygienic requirement for maintaining biological balance. The soil in the cities is no longer able to cope with its task without the help of man. The only way out of this situation is the complete neutralization and destruction of waste in accordance with hygienic requirements.

Therefore, the construction of public utilities should be aimed at preserving the natural ability of the soil to self-purify, and if this ability has already become unsatisfactory, then it must be restored artificially.

The most unfavorable is the toxic effect of industrial waste, both liquid and solid. An increasing amount of such waste is getting into the soil, which it is not able to cope with. So, for example, soil contamination with arsenic was found in the vicinity of superphosphate production plants (within a radius of 3 km). As is known, some pesticides, such as organochlorine compounds that have entered the soil, do not decompose for a long time.

The situation is similar with some synthetic packaging materials (polyvinyl chloride, polyethylene, etc.).

Some toxic compounds sooner or later enter groundwater, as a result of which not only the biological balance of the soil is disturbed, but the quality of groundwater also deteriorates to such an extent that it can no longer be used as drinking water.
Percentage of the amount of basic synthetic materials contained in household waste (garbage)

*
Together with waste of other plastics that harden under the action of heat.
The problem of waste has increased today also because part of the waste, mainly human and animal feces, is used to fertilize agricultural land [feces contain a significant amount of nitrogen-0.4-0.5%, phosphorus (P203)-0.2-0 .6%, potassium (K? 0) -0.5-1.5%, carbon-5-15%]. This problem of the city has spread to the city's neighborhoods.
4.4.
The role of soil in the spread of various diseases

Soil plays a role in the spread of infectious diseases. This was reported back in the last century by Petterkoffer (1882) and Fodor (1875), who mainly highlighted the role of soil in the spread of intestinal diseases: cholera, typhoid, dysentery, etc. They also drew attention to the fact that some bacteria and viruses remain viable and virulent in the soil for months. Subsequently, a number of authors confirmed their observations, especially in relation to urban soil. For example, the causative agent of cholera remains viable and pathogenic in groundwater from 20 to 200 days, the causative agent of typhoid fever in feces - from 30 to 100 days, the causative agent of paratyphoid - from 30 to 60 days. (In terms of the spread of infectious diseases, urban soil is much more dangerous than field soil fertilized with manure.)

To determine the degree of soil contamination, a number of authors use the determination of the bacterial number (E. coli), as in determining the quality of water. Other authors consider it expedient to determine, in addition, the number of thermophilic bacteria involved in the process of mineralization.

The spread of infectious diseases through the soil is greatly facilitated by watering the land with sewage. At the same time, the mineralization properties of the soil also deteriorate. Therefore, watering with wastewater should be carried out under constant strict sanitary supervision and only outside the urban area.

4.5.
Harmful effect of the main types of pollutants (solid and liquid waste) leading to soil degradation

4.5.1.
Neutralization of liquid waste in the soil

In a number of settlements that do not have sewage systems, some waste, including manure, is neutralized in the soil.

As you know, this is the easiest way to neutralize. However, it is admissible only if we are dealing with a biologically valuable soil that has retained the ability to self-purify, which is not typical for urban soils. If the soil no longer possesses these qualities, then in order to protect it from further degradation, there is a need for complex technical facilities for the neutralization of liquid waste.

In a number of places, waste is neutralized in compost pits. Technically, this solution is a difficult task. In addition, liquids are able to penetrate the soil over fairly long distances. The task is further complicated by the fact that urban wastewater contains an increasing amount of toxic industrial waste that worsens the mineralization properties of the soil to an even greater extent than human and animal feces. Therefore, it is permissible to drain into compost pits only wastewater that has previously undergone sedimentation. Otherwise, the filtration capacity of the soil is disturbed, then the soil loses its other protective properties, the pores gradually become blocked, etc.

The use of human feces to irrigate agricultural fields is the second way to neutralize liquid waste. This method presents a double hygienic danger: firstly, it can lead to soil overload; secondly, this waste can become a serious source of infection. Therefore, feces must first be disinfected and subjected to appropriate treatment, and only then used as a fertilizer. There are two opposing points of view here. According to hygienic requirements, faeces are subject to almost complete destruction, and from the point of view of the national economy, they represent a valuable fertilizer. Fresh faeces cannot be used for watering gardens and fields without first disinfecting them. If you still have to use fresh feces, then they require such a degree of neutralization that they are almost of no value as a fertilizer.

Feces can be used as fertilizer only in specially designated areas - with constant sanitary and hygienic control, especially for the state of groundwater, the number of flies, etc.

The requirements for the disposal and disposal of animal faeces in the soil do not differ in principle from those for the disposal of human faeces.

Until recently, manure has been a significant source of valuable nutrients for agriculture to improve soil fertility. However, in recent years, manure has lost its importance partly due to the mechanization of agriculture, partly due to the increasing use of artificial fertilizers.

In the absence of appropriate treatment and disposal, manure is also dangerous, as well as untreated human feces. Therefore, before being taken to the fields, manure is allowed to mature so that during this time (at a temperature of 60-70 ° C) the necessary biothermal processes can occur in it. After that, the manure is considered "mature" and freed from most of the pathogens contained in it (bacteria, worm eggs, etc.).

It must be remembered that manure stores can provide ideal breeding grounds for flies that promote the spread of various intestinal infections. It should be noted that flies for reproduction most readily choose pig manure, then horse, sheep and, last but not least, cow manure. Before exporting manure to the fields, it must be treated with insecticidal agents.
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