Processes of self-purification of water objects. Processes contributing to the self-purification of water bodies

5 Main processes of water self-purification in a water body

Self-purification of water in reservoirs is a set of interrelated hydrodynamic, physicochemical, microbiological and hydrobiological processes leading to the restoration of the original state of a water body.

Among the physical factors, the dilution, dissolution and mixing of incoming contaminants is of paramount importance. Good mixing and reduction of suspended particles concentrations is ensured by the fast flow of the rivers. It contributes to the self-purification of water bodies by settling to the bottom of insoluble sediments, as well as settling polluted waters. In areas with a temperate climate, the river cleans itself after 200-300 km from the place of pollution, and in the Far North - after 2 thousand km.

Disinfection of water occurs under the influence ultraviolet radiation sun. The effect of disinfection is achieved by the direct destructive effect of ultraviolet rays on protein colloids and enzymes of the protoplasm of microbial cells, as well as spore organisms and viruses.

Of the chemical factors of self-purification of water bodies, it should be noted the oxidation of organic and inorganic substances. Often give an assessment of the self-purification of the reservoir in relation to easily oxidized organic matter or general content organic substances.

The sanitary regime of a reservoir is characterized primarily by the amount of oxygen dissolved in it. It should beat at least 4 mg per 1 liter of water at any time of the year for reservoirs for reservoirs of the first and second types. The first type includes water bodies used for drinking water supply of enterprises, the second - used for swimming, sporting events, as well as those located within the boundaries of settlements.

The biological factors of self-purification of the reservoir include algae, molds and yeast fungi. However, phytoplankton does not always have a positive effect on self-purification processes: in some cases, the massive development of blue-green algae in artificial reservoirs can be considered as a process of self-pollution.

Representatives of the animal world can also contribute to the self-purification of water bodies from bacteria and viruses. Thus, the oyster and some other amoeba adsorb intestinal and other viruses. Each mollusk filters more than 30 liters of water per day.

The purity of reservoirs is unthinkable without the protection of their vegetation. Only on the basis profound knowledge ecology of each reservoir, effective control The development of various living organisms inhabiting it can achieve positive results, ensure transparency and high biological productivity of rivers, lakes and reservoirs.

Other factors also adversely affect the processes of self-purification of water bodies. Chemical pollution of water bodies with industrial wastewater, biogenic elements (nitrogen, phosphorus, etc.) inhibits natural oxidative processes kills microorganisms. The same applies to the discharge of thermal wastewater from thermal power plants.

A multi-stage process, sometimes stretching for a long time - self-cleaning from oil. Under natural conditions, the complex of physical processes of self-purification of water from oil consists of a number of components: evaporation; settling of lumps, especially those overloaded with sediment and dust; adhesion of lumps suspended in the water column; floating lumps forming a film with inclusions of water and air; reducing the concentration of suspended and dissolved oil due to settling, floating and mixing with clean water. The intensity of these processes depends on the properties specific type oil (density, viscosity, coefficient thermal expansion), the presence of colloids in the water, suspended and entrained plankton particles, etc., air temperature and from sunlight.

6 Measures to intensify the processes of self-purification of a water body

Self-purification of water is an indispensable link in the water cycle in nature. Contamination of any type during self-cleaning water bodies Ultimately, they turn out to be concentrated in the form of waste products and dead bodies of microorganisms, plants and animals that feed on them, which accumulate in the silt mass at the bottom. Water bodies in which the natural environment can no longer cope with incoming pollutants are degrading, and this is mainly due to changes in the composition of the biota and disturbances. food chains, primarily the microbial population of the water body. Self-purification processes in such water bodies are minimal or completely stop.

Such changes can only be halted by purposefully influencing the factors that contribute to reducing the formation of waste volumes and reducing pollution emissions.

The task set can be solved only by implementing a system of organizational measures and engineering and reclamation work aimed at restoring the natural environment of water bodies.

When restoring water bodies, it is advisable to start the implementation of a system of organizational measures and engineering and reclamation work with the arrangement of the watershed, and then carry out the cleaning of the water body, followed by the arrangement of coastal and floodplain territories.

The main objective of the ongoing environmental protection measures and engineering and reclamation work in the catchment area is to reduce the generation of waste and prevent unauthorized discharge of pollutants onto the relief of the catchment area, for which the following measures are carried out: introduction of a waste generation rationing system; organization of environmental control in the system of production and consumption waste management; conducting an inventory of facilities and locations for production and consumption waste; reclamation of disturbed lands and their arrangement; tightening fees for unauthorized discharge of pollutants onto the terrain; introduction of low-waste and waste-free technologies and water recycling systems.

Environmental protection measures and works carried out in coastal and floodplain areas include works on leveling the surface, flattening or terracing slopes; construction of hydrotechnical and recreational structures, strengthening of the banks and the restoration of a stable grass cover and tree and shrub vegetation, which subsequently prevent erosion processes. Landscaping works are carried out to restore the natural complex of the water body and transfer most of the surface runoff to the underground horizon in order to clean it up using rocks coastal zone and floodplain lands as a hydrochemical barrier.

The shores of many water bodies are littered, and the waters are polluted with chemicals, heavy metals, oil products, floating debris, and some of them are eutrophicated and silted. It is impossible to stabilize or activate self-purification processes in such water bodies without special engineering and reclamation intervention.

The purpose of performing engineering and reclamation measures and environmental protection work is to create conditions in water bodies that ensure the effective functioning of various water purification facilities, and to perform work to eliminate or reduce the negative impact of sources of distribution of pollutants, both off-channel and channel origin.

The structural and logical scheme of organizational, engineering, reclamation and environmental measures aimed at restoring the natural environment of a water body is shown in Figure 1.

Only a systematic approach to the problem of restoring water bodies makes it possible to improve the quality of water in them.

Technological

Reclamation of disturbed lands

Reclamation of silted and polluted water bodies

Activation of self-cleaning processes

System of measures aimed at restoring the natural environment of water bodies

Arrangement of coastal territories, strengthening of coasts

Measures and work carried out on the watershed

Works performed in the water area of a water body

Water purification

Elimination of sources of channel pollution

Improvement of environmental legislation and regulatory framework

Increasing responsibility

Waste regulation, environmental control, inventory of waste disposal and disposal sites

Creation of water protection zones

Rehabilitation of contaminated lands and territories

Organizational

Sapropels

Mineral silts

Technogenic silts

floating debris

Restoration of the natural environment, natural waters of ecosystems and improvement of human habitation and health

From chemical and bacteriological contamination

From crude oil and petroleum products

Monitoring system

Conclusion

At present, indicators that determine the state of public health and the quality of the environment are a measure of the level of environmental safety of a person and the natural environment. Solving the problem of identifying damage to public health and environmental quality is very complex and should be carried out using modern information technologies, the most promising of which is the technology of geographic information systems, which can be used to support the process of making and implementing economic decisions in environmental impact assessment and environmental expertise. One of the structural elements of a GIS is a database that stores all the information available in the system: graphic (spatial) data; thematic and reference data (information on the territorial and temporal reference of thematic information, reference data on MPC, background values, etc.).

Databases are formed based on the purpose of the study and the availability of reliable information on the state of atmospheric air, surface and groundwater, soil, snow cover, public health and other information.

Forecasting environmental situation in the zone of possible activity of an economic or other facility and decision-making in the event of hazardous pollution and accidental emissions are based, as a rule, on the use of intuitive procedures based on information that is mostly incomplete, not entirely accurate, and sometimes unreliable.

In these cases, given the need for prompt decision-making, it is advisable to use powerful modern tools of artificial intelligence systems and decision-making. An intelligent system of environmental safety allows users, using fuzzy criteria for presenting knowledge about information, to receive proposals for possible solutions based on the rules of inference of data and knowledge of the expert system and on the method of inaccurate reasoning.

Analysis of works devoted to development intelligent systems environmental safety industrial enterprises and territories, shows that the development of such systems in Russia is at the initial level. In order to organize an effective system of environmental safety in an industrial region as an integral system for monitoring, assessing and predicting dangerous changes in the natural environment, it is necessary to build a network of ground, underground and aerospace observations of all components of the natural environment. At the same time, in order to obtain an objective picture of the state of the environment and to resolve issues at the regional level (expertise, decision-making, forecast), it is necessary to organize environmental monitoring of all major sources of pollution, constant monitoring of the state of environmental parameters that change as a result of the impact of pollution by waste coming from various sources.

Most of the known environmental monitoring systems are regional systems, their task is to monitor the ecological state of the region as a whole. To ensure environmental safety, a regional monitoring system is not enough; more accurate information about local sources of pollution on an enterprise scale is needed.

Therefore, relevant and important task what remains is the creation of automated systems for environmental monitoring, systems for preparing and making decisions, which will ensure a high-quality assessment of the impact on the environment of the designed objects of economic and other activities.

Bibliography

Surfactants, petroleum products, nitrites; the highest - suspended solids, BODtot, sulfates, in connection with this, the maximum allowable discharge of these substances is higher. Conclusion thesis the environmental hazard of wastewater from the food industry was assessed. The main components of food industry wastewater are considered. The influence of wastewater from the food industry on the state of natural ...

It is carried out in special facilities - electrolyzers. Wastewater treatment using electrolysis is effective in lead and copper plants, paint and varnish and some other industries. Contaminated wastewater is also treated using ultrasound, ozone, ion exchange resins and high pressure, cleaning by chlorination has proven itself well. Among the methods of wastewater treatment...

And the effect of cleaning from undissolved impurities. One of the main conditions for the normal operation of sedimentation tanks is uniform distribution between them incoming waste water. Vertical settling tanks For the treatment of industrial wastewater, vertical settling tanks with an upward flow are used. Settlers are cylindrical or rectangular in shape. Waste water is introduced in the center through...

Territories, and on the other hand, on the quality of groundwater and its impact on human health. Chapter III. ECONOMIC CHARACTERISTICS OF WATER USE IN THE KURSK REGION 3.1 general characteristics 3.1.1 Key indicators of water use Kursk region is located in the southwest of the European territory of the Russian Federation within the Central Black Earth economic region. Square...

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MINISTRY OF EDUCATION AND SCIENCE OF THE RUSSIAN FEDERATION

FEDERAL AGENCY FOR EDUCATION AND SCIENCE

MARI STATE TECHNICAL UNIVERSITY

Department of environmental management

Course work

discipline: Ecological bases of environmental impact assessment

on the topic: Patterns of selfwater purification in water bodies

Completed: Art. gr. PO-41 Konakova M.E.

Checked by: Associate Professor Khvastunov A.I.

Yoshkar-Ola

Introduction

1 Concept, stages of environmental impact assessment

1.1 The concept of EIA

1.2 Stages of the environmental impact assessment procedure

1.3 Assessment of impacts on surface waters

2 Sources of information when drawing up the terms of reference for the EIA

3 Performance indicators treatment facilities

4 Sources of pollution of a water body depending on the landscape structure of the area

5 Main processes of water self-purification in a water body

6 Measures to intensify the processes of self-purification of a water body

Conclusion

Bibliography

Introduction

At all times, water was considered the priceless moisture of life. And although those years are far behind when it was necessary to take it in rivers, ponds, lakes and carry it several kilometers to the house on yokes, trying not to spill a single drop, a person still treats water with care, taking care of the cleanliness of natural reservoirs, of good condition of wells, columns, plumbing systems. In connection with the ever-growing needs of industry and agriculture in fresh water, the problem of preserving existing water resources is becoming increasingly acute. After all, water suitable for human needs, as statistics show, is not so much on globe. It is known that more than 70% of the Earth's surface is covered with water. About 95% of it falls on the seas and oceans, 4% on the ice of the Arctic and Antarctic, and only 1% is fresh water rivers and lakes. Significant sources of water are underground, sometimes at great depths.

The 20th century is characterized by an intensive growth of the world's population and the development of urbanization. Giant cities with a population of more than 10 million people appeared. The development of industry, transport, energy, industrialization of agriculture led to the fact that anthropogenic impact on the environment has become global. Increasing the effectiveness of measures to protect the environment is associated primarily with the widespread introduction of resource-saving, low-waste and non-waste technological processes, and a decrease in air and water pollution.

Environmental protection is a very multifaceted problem, which is dealt with, in particular, by engineering and technical workers of almost all specialties that are associated with economic activity in settlements and at industrial enterprises, which can be a source of pollution, mainly air and aquatic environment.

The United Nations Organization in the declaration of the Conference on Environment and Development (Rio de Janeiro, June 1992), which our country also signed, determined general principles legal approach to nature protection; pointed out that all states should have tough and at the same time reasonable environmental legislation. At present, a system has been created in Russia legal protection nature, which is a set of legal norms established by the state and arising as a result of their implementation of legal relations aimed at the implementation of measures to preserve the natural environment, rational use natural resources, health improvement human environment living environment for the benefit of present and future generations.

One of the mechanisms for implementing the legal protection of nature is the environmental impact assessment, which is the most effective managerial lever for rational nature management and environmental protection, which ultimately should decide environmental problems Russia.

AT federal law"On Environmental Protection" dated January 10, 2002, Chapter VI (Art. 32, 33) is devoted to environmental impact assessment and environmental expertise. These procedures are a mandatory measure in relation to planned economic or other activities that can have a direct or indirect impact on the environment, regardless of the form of ownership and departmental affiliation of the subjects of this activity. Environmental impact assessment and environmental expertise are interrelated elements of a single legal institution- impact assessment and environmental expertise.

1 Concept, stages of environmental impact assessment

1 . 1 The concept of EIA

So far, the only valid Russian regulatory document regulating the environmental impact assessment (EIA) _ Regulation "On environmental impact assessment in the Russian Federation" (approved by order of the Ministry of Natural Resources of Russia dated July 18, 1994 No. 222), determined the environmental impact assessment environment as "a procedure for taking into account the environmental requirements of the legislation of the Russian Federation in the preparation and adoption of decisions on the socio-economic development of society in order to identify and take the necessary and sufficient measures to prevent possible environmental and related social, economic and other consequences of the implementation of an economic or other activities".

At first glance, concepts similar to each other have some semantic differences.

EIA _ is a "procedure for taking into account" environmental requirements (or justification _ informational measure) in preparing the optimal solution (during the design).

EIA is inherently a process of studying the impact of a proposed activity and predicting its consequences for the environment and human health.

The purpose of the EIA is to identify and adopt (ie develop) the necessary environmental measures.

The results of the EIA are part of the documentation submitted for environmental review. They are formed by: information on the scale and nature of the impact on the environment of the planned activity, alternatives for its implementation, assessment of the actual consequences of the activity, etc. They also serve as the basis for monitoring and environmental control over the activities being implemented.

EIA tasks in the current Russian legislation still largely unexplored, but general view they can be formulated as follows: organizing and conducting (at the stage of preparing a decision) comprehensive, objective, scientific research and analysis of objects of expertise from the standpoint of efficiency, completeness, validity and sufficiency of the measures provided for in them, the correctness of determining the degree of environmental risk and the dangers of planned or ongoing activities, as well as providing environmental forecasting based on information about the state and possible changes in the environmental situation, due to the location and development of productive forces that do not lead to negative environmental impacts (OS), i.e. determining the likelihood of environmentally harmful impacts and possible social, economic and environmental impacts.

1 . 2 Stages of the environmental impact assessment procedure

The Regulations on the assessment of the impact of planned economic and other activities on the environment in the Russian Federation, approved by the order of the State Committee for Ecology of Russia dated May 16, 2000 No. 372, provide for the following stages of the assessment:

1. Notification, preliminary assessment and preparation of terms of reference for the EIA.

2. Conducting studies on the EIA of the planned economic and other activities and preparing a preliminary version of the relevant materials.

3. Preparation of the final version of the EIA materials. The principles, procedure and other information about the EIA are described in detail in the regulatory documents and literature.

3.1. Notification, preliminary assessment and preparation of terms of reference for the EIA

The first stage of the EIA begins simultaneously with the development of the concept of the proposed activity.

During the EIA process, the following tasks are solved at this stage:

1. Identification of the possibility of additional anthropogenic load on the environment of a given territory.

2. Determination of the permissible scale of involvement in the processing of natural resources and energy in a given territory.

3. Consideration alternative ways improvement of the environmental situation, including by reducing the technogenic load of other sources of impact.

4. Formation of project proposals for the implementation of planned activities.

5. Preparation of terms of reference for the assessment of the established content.

The basis for the development of the concept of the planned activity can be the schemes for the placement and development of productive forces, the schemes for the placement and development of industries and other documents replacing them.

At the stage of developing the concept of the planned activity, the possibilities of achieving the indicators defined in these documents in relation to a specific object are taken into account, the issues of the possibility of influencing the environment are worked out in more detail, taking into account the dynamics of the actual environmental situation in the region.

The necessity and expediency of implementing the design concept with the identification, analysis and evaluation of real alternatives for the development of activities in the given territory is substantiated.

The concept necessarily evaluates alternative sources of raw materials and energy, secondary raw materials and energetic resources and production waste, a search is underway for new areas of application for the waste of the future facility.

Another key issue of the concept is to ensure environmental safety, including solving the problems of localization and elimination of the consequences of accidents and disasters.

The concept should provide for an assessment of the technological level of the project and exclude technological solutions that may become obsolete by the time the construction of the facility is completed.

When developing the concept of the proposed activity, special attention is paid to assessing the progressiveness of decisions, taking into account possible changes technical and economic indicators, tightening of industry environmental standards for impact on the environment, changes in prices for resources and payments for environmental pollution.

Thus, the EIA begins when the customer of the planned activity forms a proposal for the implementation of a project or program (the concept of the proposed activity). Based on the results of this stage, the customer prepares a "Notice of Intent", which contains:

1) preliminary list intentions of the customer by the nature of the planned activity, including plans for proposed actions, preliminary assessment the impact on the environment and the implementation of environmental protection measures, the specifics of the annual plans for these works, the list of infrastructure facilities, etc.;

2) a list of real and feasible alternatives to the project under consideration (one of the alternatives is necessarily the option of abandoning the activity).

Based on the results of the preliminary EIA, the customer draws up the terms of reference for the EIA.

When drawing up the terms of reference, the customer takes into account the requirements of specially authorized bodies for the protection of the environment, as well as the opinions of other participants in the process at their request; it is available to the public at all times during the assessment. The assignment is part of the EIA materials.

Local authorities and administrations, after receiving and considering the "Notice of Intent" from the customer, issue (or do not issue) him a permit for design and survey.

3.2. Conducting EIA studies and preparing a preliminary version of the relevant materials

The purpose of the second stage of the EIA is to identify all possible impacts of the future economic or other object on the environment, taking into account natural conditions specific territory. Research is carried out by the customer (executor) in accordance with the terms of reference, taking into account alternatives for implementation, goals of the activity, ways to achieve them.

The second stage of the EIA is a systematic, reasonable assessment environmental aspects project proposal based on the use of complete and reliable initial information, means and methods of measurement, calculations, estimates in accordance with the legislation of the Russian Federation,

The study includes determining the characteristics of the planned economic and other activities and possible alternatives (including the abandonment of activities); analysis of the state of the territory, which may be affected by the proposed activity (the state of the natural environment, the presence and nature of anthropogenic load, etc.); identification of possible impacts of the proposed activity on the environment, taking into account alternatives; assessment of environmental impacts of activities (probability of risk occurrence, degree, nature, scale, distribution area, as well as forecasting environmental and related social and economic consequences); determination of measures that reduce, mitigate or prevent negative impacts, assessment of their effectiveness and feasibility; assessment of the significance of residual impacts on the environment and their consequences; preparation of a preliminary version of materials on environmental impact assessment of the proposed activity (including a summary for non-specialists) and a number of other issues.

3.3. Preparation of the final version of the EIA materials

The purpose of the third stage of the EIA is to correct projects that have passed the EIA stage. The approach suggested for use at this stage is to make decisions step by step:

1) for projects that do not require additional scientific research;

2) for projects requiring only minor research;

3) for complex and complex project proposals that require the involvement of extensive scientific research.

Many project proposals can be considered by analogy with those already taking place in the selected area or in an area with similar natural conditions. In such cases, methods of peer review and analogies are applied. The preliminary version of the materials is analyzed and comments, suggestions and information received from the participants in the evaluation process at the discussion stage are taken into account. The final version of the evaluation materials should also include the minutes of public hearings (if any).

The Environmental Impact Statement (EPS) is considered as a report by the developer of project documentation on the work done on the EIA of the proposed activity and is submitted by the customer as part of the project documentation. The ZEP is drawn up as a separate document and includes:

1) title page;

2) a list of organizations and specific developers involved in the EIA:

work manager, coordinator,

specialists responsible for the sections,

specialists responsible for environmental and socio-economic sections;

3) the main sections of research carried out at all stages of the EIA:

the purpose and necessity of the implementation of the planned activity,

technological analysis of project proposals, analysis of the natural conditions of the territories and the existing technogenic load,

analysis and assessment of sources and types of impact, identification of especially significant public positions, forecast of environmental changes in environmentally significant positions;

4) conclusions drawn on the basis of scientific research, surveys and public hearings of the EIS;

5) environmental consequences of the impact on the environment, the health of the population and its livelihoods;

6) the obligations of the customer to implement the measures and activities set out in the project documentation, in accordance with environmental safety and guaranteeing the fulfillment of these obligations for the entire period of the object's life cycle.

The EPZ is transferred by the customer to all interested parties participating in the discussion of the EIA, namely:

state authorities, management and control;

the public and interested parties who exercise control over the fulfillment of the obligations assumed by the customer when deciding on the implementation of the planned activity.

The final version of the materials is approved by the customer, is used in the preparation of the relevant documentation and, thus, is submitted to the state, as well as to the public.

1. 3 Assessment of impact on surface waters

Condition assessment surface water has two aspects: quantitative and qualitative. Both aspects constitute one of the most important conditions for the existence of living beings, including humans.

Surface water quality assessment is relatively well developed and based on legislative, regulatory and policy documents.

The fundamental law in this area is the Water Code of the Russian Federation; sanitary and epidemiological requirements for water bodies are determined by Art. 18 of the Federal Law "On the sanitary and epidemiological well-being of the population". Regulatory and directive documents include: Decree of the Government of the Russian Federation of December 19, 1996 No. 1504 "On the procedure and approval of standards for the maximum permissible harmful effects of MPE on water bodies"; Guidelines for the development of PDS standards harmful substances into surface water bodies approved by the order of the Ministry of Natural Resources of Russia on December 17, 1998; Guidelines for the development of MPE standards for surface water bodies, approved by the Russian Ministry of Natural Resources, the State Committee for Ecology of Russia on February 26, 1999, Methodological guidelines for the development of MPE standards for groundwater bodies and MPDs for harmful substances in groundwater bodies, approved by the Russian Ministry of Natural Resources on December 29, 1998. ; Sanitary rules and norms for the protection of surface waters from pollution (1988), as well as existing standards.

Assessing the quantitative aspects of water resources (including their pollution) has a dual purpose. Firstly, it is necessary to assess the possibilities of meeting the needs of the planned activity in water resources, and secondly, the consequences of a possible withdrawal of the remaining resources for other facilities and the life of the population.

For such assessments, it is necessary to have data on the hydrological features and patterns of the regime of water bodies that are sources of water supply, as well as the existing levels of consumption and volumes of water resources required for the implementation of the project.

The latter also includes the technological scheme of water consumption (irreversible, reverse, seasonal, etc.) and is an assessment of the direct impact of the planned activity on the amount of water resources.

However, the indirect impact, which ultimately affects the hydrological characteristics of water bodies, is also of great importance. Indirect impacts include disturbance of the riverbed (by dredges, dredgers, etc.), changes in the surface of the catchment area (plowing of land, deforestation), springing (flooding) during construction or lowering of groundwater, and much more. It is necessary to identify and analyze all possible types of impacts and their consequences for assessing the state of water resources.

Two most capacious indicators are recommended as criteria for assessing surface water resources: the value of surface (river) runoff or changes in its regime in relation to a particular basin and the value of the volume of one-time water withdrawal.

The most common and significant factor causing water scarcity is pollution. water sources, which is usually judged from the observational data of the monitoring services of Roshydromet and other departments that control the state of the aquatic environment.

Each water body has its own natural hydrochemical quality, which is its initial property, which is formed under the influence of hydrological and hydrochemical processes occurring in the reservoir, as well as depending on the intensity of its external pollution. The cumulative impact of these processes can both neutralize the harmful effects of getting into water bodies anthropogenic pollution(self-purification of water bodies), and lead to a persistent deterioration in the quality of water resources (pollution, clogging, depletion).

The ability of each water body to self-purify, i.e. the amount of pollutants that can be processed and neutralized by a water body, depends on various factors and obeys certain patterns (the incoming amount of water diluting polluted effluents, its temperature, changes in these indicators over the seasons, the qualitative composition of pollutants ingredients, etc.).

One of the main factors determining the possible levels of pollution of water bodies, in addition to their natural properties, is the initial hydrochemical state that occurs under the influence of anthropogenic activity.

Predictive estimates of the state of pollution of water bodies can be obtained by summing up the existing levels of pollution and additional quantities of pollutants planned for the intake of the designed facility. In this case, it is necessary to take into account both direct (direct discharge into water bodies) and indirect (surface runoff, subsoil runoff, aerogenic pollution, etc.) sources.

The main criterion for water pollution is also MPC, among which there are sanitary and hygienic (normalized according to the effect on the human body), and fisheries, developed to protect hydrobionts (living creatures of water bodies). The latter, as a rule, are stricter, since the inhabitants of water bodies are usually more sensitive to pollution than humans.

Accordingly, reservoirs are divided into two categories: 1) drinking and cultural purposes; 2) for fishery purposes. In water bodies of the first type, the composition and properties of water must comply with the standards in sites located at a distance of 1 km from the nearest water use point. In fishery reservoirs, water quality indicators should not exceed the established standards at the place of wastewater discharge in the presence of a current, in its absence - no further than 500 m from the place of discharge.

The main source of information about the hydrological and hydrochemical properties of water bodies are the materials of observations carried out in the EGSEM network (Unified state system ecological monitoring) of Russia.

An important place among the criteria for environmental assessment of the state of water bodies is occupied by indicative assessment criteria. AT recent times bioindication (along with traditional chemical and physicochemical methods) has become quite widespread in assessing the quality of surface waters. According to the functional state (behavior) of the test objects (crustaceans - daphnia, algae - chlorella, fish - guppies), it is possible to rank the waters according to the classes of states and, in essence, give an integral assessment of their quality, as well as determine the possibility of using water for drinking and other related purposes. biota, goals. The limiting factor in the use of the biotesting method is the duration of the analysis (at least 4 days) and the lack of information about the chemical composition of water.

It should be noted that due to the complexity and diversity of the chemical composition of natural waters, as well as the increasing amount of pollutants (more than 1625 harmful substances for drinking and cultural water bodies, more than 1050 for fishery water bodies), methods have been developed for a comprehensive assessment of the contamination of surface waters, which are fundamentally divided into two groups.

The first includes methods that allow assessing the quality of water by a combination of hydrochemical, hydrophysical, hydrobiological, microbiological indicators.

Water quality is divided into classes with varying degrees of contamination. However, the same state of water according to different indicators can be assigned to different quality classes, which is a disadvantage of these methods.

The second group consists of methods based on the use of generalized numerical characteristics of water quality, determined by a number of basic indicators and types of water use. Such characteristics are water quality indices, coefficients of its pollution.

In hydrochemical practice, the water quality assessment method developed at the Hydrochemical Institute is used. The method allows to produce unequivocal assessment water quality, based on a combination of the level of water pollution by the totality of pollutants present in it and the frequency of their detection.

Based on the material provided and taking into account the recommendations set out in the relevant literature, when conducting an impact assessment on surface waters, it is necessary to study, analyze and document the following:

1) hydrographic characteristics of the territory;

2) characteristics of water supply sources, their economic use;

3) assessment of the possibility of water intake from a surface source for production needs in natural conditions (without regulation of river flow; taking into account the existing regulation of river flow);

4) the location of the water intake, its characteristics;

5) characteristics of the water body in the design section of the water intake (hydrological, hydrochemical, ice, thermal, speed modes runoff, sediment regime, channel processes, dangerous phenomena: congestion, presence of sludge);

6) organization of a sanitary protection zone of water intake;

7) water consumption during the construction of the facility, the water management balance of the enterprise, assessment of the rationality of water use;

8) wastewater characteristics - flow rate, temperature, composition and concentrations of pollutants;

9) technical solutions for wastewater treatment during the construction of the facility and its operation - short description treatment facilities and installations ( technology system, type, performance, main design parameters), expected cleaning efficiency;

10) reuse of water, recycling water supply;

11) methods of disposal of sewage treatment plant sludge;

12) wastewater discharge - place of discharge, design features release, wastewater disposal mode (frequency of discharges);

13) calculation of MPD of treated wastewater;

14) characteristics of residual pollution during the implementation of measures for wastewater treatment (in accordance with the MPD);

15) assessment of changes in surface runoff (liquid and solid) as a result of redevelopment of the territory and removal of the vegetation layer, identification of the negative consequences of these changes on the water regime of the territory;

16) assessment of the impact on surface water during construction and operation, including the consequences of the impact of water withdrawal on the ecosystem of the reservoir; thermal, chemical, biological pollution, including in case of accidents;

17) assessment of changes in channel processes associated with the laying of linear structures, construction of bridges, water intakes and identification of the negative consequences of this impact, including on hydrobionts;

18) forecast of the impact of the proposed facility (water withdrawal, residual pollution from the discharge of treated wastewater, change temperature regime etc.) on aquatic flora and fauna, economic and recreational use of water bodies, living conditions of the population;

19) organization of control over the state of water bodies;

20) volume and total cost water protection measures, their effectiveness and sequence of implementation, including measures to prevent and eliminate the consequences of accidents.

2 Sources of information when drawing up the terms of reference for the EIA

Public information and participation is carried out at all stages of the EIA. Public participation in the preparation and discussion of environmental impact assessment materials is provided by the customer, organized by the authorities local government or relevant government authorities with the assistance of the customer.

Informing the public and other participants in the EIA at the first stage is carried out by the customer. The customer ensures publication in official publications federal bodies executive authorities (for objects of expertise at the federal level), executive authorities of the constituent entities of the Russian Federation and local governments, on whose territory the implementation of the EIA object is planned, the following information: name, purpose and location of the planned activity; name and address of the customer or his representative; approximate timing of the EIA; body responsible for organizing public discussion; the intended form of public discussion, as well as the form for submitting comments and suggestions; terms and place of availability of the terms of reference for environmental impact assessment. Additional information to participants in the EIA can be carried out by disseminating information on radio, television, periodicals, the Internet and other means.

Within 30 days from the date of publication of information, the customer (executor) accepts and documents comments and suggestions from the public. These comments and suggestions are taken into account when drawing up the terms of reference and should be reflected in the EIA materials. The customer is obliged to provide access to terms of reference the public concerned and other participants in the EIA from the moment of its approval until the end of the EIA process.

After the preparation of the preliminary version of the environmental impact assessment materials, the contracting authority must provide the public with information about the timing and place of availability of the preliminary version, as well as the date and place of public discussions. This information is published in the media no later than 30 days before the end of the public discussions. Submission of a preliminary version of materials on environmental impact assessment to the public for review and submission of comments is made within 30 days, but no later than 2 weeks before the end of public discussions (public hearings).

Public discussions may be held at various forms ah: poll, public hearings, referendum, etc. When deciding on the form of holding public discussions, it is necessary to be guided by the degree of environmental hazard of the planned economic and other activities, take into account the uncertainty factor, the degree of public interest.

The procedure for conducting public hearings is determined by local governments with the participation of the customer (executor) and the assistance of the public concerned. All decisions on public participation are documented - by drawing up a protocol. It should clearly record the main issues of discussion, as well as the subject of disagreement between the public and the customer (if any). The protocol is signed by representatives of executive authorities and local self-government, citizens, public organizations (associations), the customer. The protocol of the public hearings is included as one of the appendices in the final version of the materials on the environmental impact assessment of the planned economic and other activities.

From the moment the final version of the EIA materials is approved and until a decision is made on the implementation of the proposed activity, the customer provides public access to these materials. Citizens and public organizations can send their proposals and comments on them to the customer, who ensures their documentation within 30 days after the end of the public discussion. Subsequently, proposals and comments may be sent to a specially authorized state body in the field of conducting state environmental expertise.

Requirements for environmental impact assessment materials Impact assessment materials are a set of documentation prepared during the environmental impact assessment of the proposed activity and being part of the documentation submitted for environmental expertise.

3 Indicators for evaluating the effectiveness of treatment facilities

Wastewater - these are waters used for domestic, industrial or other needs and contaminated with various impurities that have changed their original chemical composition and physical properties, as well as water flowing from the territory of settlements and industrial enterprises as a result of precipitation or watering streets. Depending on the origin of the type and composition, wastewater is divided into three main categories:

household(from toilet rooms, showers, kitchens, baths, laundries, canteens, hospitals; they come from residential and public buildings, as well as from domestic premises and industrial enterprises);

Production(water used in technological processes that no longer meet the requirements for their quality; this category of water includes water pumped to the surface of the earth during the extraction of minerals);

atmospheric(rain and melt; along with atmospheric water, water is drained from street irrigation, from fountains and drains).

In practice, the concept is also used municipal wastewater, which are a mixture of domestic and industrial wastewater. Household, industrial and atmospheric wastewater is discharged both jointly and separately.

Wastewater is a complex heterogeneous mixture containing impurities of organic and mineral origin, which are in an undissolved, colloidal and dissolved state.

Some parameters to be defined compulsory program water quality monitoring:

Chroma- this is an indicator of water quality, characterizing the intensity of water color and due to the content of colored compounds, which is expressed in degrees of the platinum-cobalt scale. It is determined by comparing the color of the test water with standards.

Transparency (light transmission) due to their color and turbidity, i.e. the content in them of various colored and suspended organic and mineral substances.

Depending on the degree of transparency, water is conditionally divided into transparent, slightly opalescent, opalescent, slightly turbid, turbid and highly turbid.

Turbidity- caused by the presence of finely dispersed impurities due to insoluble or colloidal inorganic and organic substances various origins. Qualitative determination is carried out descriptively: weak opalescence, opalescence, weak, noticeable and strong turbidity.

Smell- this is the property of water to cause specific irritation of the mucous membrane of the nasal passages in humans and animals. The smell of water is characterized by intensity, which is measured in points. The smell of water is caused by volatile odorous substances entering the water as a result of the vital processes of aquatic organisms, during the biochemical decomposition of organic substances, during chemical interaction components contained in the water, as well as with industrial, agricultural household wastewater.

suspended solids affect the transparency of water and the penetration of light into it, the temperature, the composition of the dissolved components of surface water, adsorption toxic substances, as well as on the composition and distribution of deposits and on the rate of sedimentation.

It is important to determine the amount of suspended particles when monitoring the processes of biological and physico-chemical treatment of wastewater and when assessing the state of natural water bodies.

Hydrogen indicator- one of key indicators water quality. The concentration of hydrogen ions is of great importance for chemical and biological processes. The development and vital activity of aquatic plants, the stability of various forms of element migration, the aggressive effect of water on metals and concrete depend on the pH value. The pH value of water also affects the processes of transformation of various forms nutrients, changes the toxicity of pollutants.

Redox potential- a measure of the chemical activity of elements or their compounds in reversible chemical processes associated with a change in the charge of ions in solutions.

chlorides- the predominant anion in highly mineralized waters. The concentration of chlorides in surface waters is subject to noticeable seasonal fluctuations, which correlate with changes in the total salinity of the water.

Nitrogen ammonium salts- the content of ammonium ions in natural waters varies from 10 to 200 µg/dm 3 in terms of nitrogen. The presence of ammonium ions in unpolluted surface waters is mainly associated with the processes of biochemical degradation of protein substances, deamination of amino acids, and decomposition of urea under the action of urease. The main sources of ammonium ions in water bodies are livestock farms, domestic wastewater, surface runoff from farmland when using ammonium fertilizers, and wastewater from food, wood chemical and chemical industries.

An increased concentration of ammonium ions can be used as an indicator reflecting the deterioration of the sanitary condition of a water body, the process of pollution of surface and ground waters, primarily by domestic and agricultural effluents.

MPC BP of salt ammonium is 0.4 mg/l for nitrogen (the limiting indicator of harmfulness is toxicological).

Nitrates- the main processes aimed at lowering the concentration of nitrates are their consumption by phytoplankton and denitrifying bacteria, which, in the absence of oxygen, use the oxygen of nitrates for the oxidation of organic substances.

In surface waters, nitrates are in dissolved form. The concentration of nitrates in surface waters is subject to noticeable seasonal fluctuations: it is minimal during the growing season, it increases in autumn and reaches a maximum in winter, when organic forms are decomposed into mineral ones with minimal nitrogen consumption. Amplitude seasonal fluctuations can serve as one of the indicators of eutrophication of a water body.

MPC vr - 40 mg/l (according to NO3-) or 9.1 mg/l (according to nitrogen).

Nitrites- represent an intermediate step in the chain of bacterial processes of ammonium oxidation to nitrates and, on the contrary, reduction of nitrates to nitrogen and ammonia. Similar redox reactions are typical for aeration stations, water supply systems and natural waters themselves.

MPC vr - 0.08 mg/l in the form of NO2- ion or 0.02 mg/l in terms of nitrogen.

Aluminum- in natural waters aluminum is present in ionic, colloidal and suspended forms. Migration ability is low. It forms fairly stable complexes, including organomineral complexes that are in water in a dissolved or colloidal state.

Aluminum ions are toxic to many types of aquatic organisms and to humans; toxicity is manifested primarily in an acidic environment.

MPC in aluminum is 0.5 mg/l (limiting indicator of harmfulness - sanitary-toxicological), MPC vr - 0.04 mg/l (limiting indicator - toxicological).

BOD full - total biochemical oxygen demand (BODtotal) is the amount of oxygen required for the oxidation of organic impurities before the start of nitrification processes. The amount of oxygen consumed for the oxidation of ammonium nitrogen to nitrites and nitrates is not taken into account when determining BOD.

The total biochemical oxygen demand BOD n for inland fishery water bodies (categories I and II) at a temperature of 20°C should not exceed 3 mg O 2 /l.

Iron total- the main sources of iron compounds in surface waters are chemical weathering processes 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 dissolved, colloidal and suspended states.

MPC in iron is 0.3 mg/l (limiting indicator of harmfulness - organoleptic). MPC vr - 0.1 mg / l (limiting indicator of harmfulness - toxicological).

Copper- 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.

Copper can form as a result of corrosion of copper pipes and other structures used in water systems.

For copper, MPC (by copper ion) is set at 1 mg/l (limiting hazard indicator - organoleptic), MPCvr - 0.001 mg/l (limiting hazard indicator - toxicological).

Nickel- in surface waters, nickel compounds are in dissolved, suspended and colloidal states, quantitative ratio between which depends on the composition of water, temperature and pH. Sorbents of nickel compounds can be iron hydroxide, organic substances, highly dispersed calcium carbonate, clays.

MPC in nickel is 0.1 mg/l (limiting hazard indicator - sanitary-toxicological), MPC vr - 0.01 mg/l (limiting hazard indicator - toxicological).

Zinc - in Zinc exists in water in ionic form or in the form of its mineral and organic complexes, sometimes found in insoluble forms.

Many zinc compounds are toxic, primarily sulfate and chloride. In the aquatic environment, the toxicity of zinc is enhanced by copper and nickel ions.

MPCv Zn2+ is 5.0 mg/l (limiting indicator - organoleptic), MPCvr Zn2+ - 0.01 mg/l (limiting indicator of harmfulness - toxicological).

Efficiency of cleaning pollutants at the OSK in Yoshkar-Ola in 2007.

Name of pollutant	Incoming SW	Purified SW	% cleaning
ammonium ion


Aluminum

BOD full
suspended solids
Iron total



Oil products


surfactant (anion act)
sulfates
Sulfides

Phosphates (according to P)


Chromium trivalent
Chromium 6-valent

4 Sources of pollution of a water body depending on the landscape structure of the area

I. Within big cities Preservation of river valleys in their natural state is impossible without constant environmental protection measures, since the negative anthropogenic impact is especially strong here.

The assessment of the quality of a site of landscape complexes is carried out according to a number of natural parameters, among which one can single out the area of the site, the biodiversity index, anthropogenic transformation, vulnerability to anthropogenic pressures, historical value, position in the ecological space, and potential recreational value. In conditions modern cities the most important factor is the ecological state of the territory, which is characterized by geoecological and biogeochemical conditions.

Ecological conditions are understood as a set of geoecological factors that determine the state of the environment within the territory under consideration. These usually include meteorological and climatic features, atmospheric pollution, the acoustic regime of the territory, its engineering-geological and hydrogeological conditions.

Biogeochemical factors include the following: the degree of disturbance and pollution soil cover, a hydrological characteristic of the territory, including an assessment of the hydrological regime of the watercourse, the degree of channel transformation, the level of water pollution in the river and other hydrochemical indicators of surface runoff within the catchment area.

Joint consideration of all these parameters allows us to give a comprehensive description of the landscape structure of the territory.

1) Assessment of geoecological factors

A) weather conditions. Meteoclimatic changes in background characteristics and redistribution of meteorological elements are determined by the relief of the river valley and its tributaries, the nature of the green cover, and depend on weather conditions. In relief depressions - river floodplains, at night, with anticyclonic weather and radiative cooling, air flow from higher adjacent territories and its stagnation are noted, fogs, surface inversions are formed, contributing to the accumulation of harmful impurities in the surface layer of the atmosphere when they enter.

B) The state of atmospheric air. Pollution of the air basin occurs due to emissions of pollutants from industrial and transport facilities located outside the site, as well as, to a large extent, from the influx of polluted air masses from adjacent territories, creating background pollution. The combination of these factors determines the high level of air pollution in general.

C) Geological environment. Geological structure is characterized by the distribution of the following genetic types of deposits: technogenic bulk soils, modern and ancient alluvial, cover, moraine fluvioglacial, moraine deposits of the Moscow or Dnieper stage of glaciation and fluvioglacial deposits of the Oka-Dnieper interglacial.

2) Assessment of biogeochemical factors

A) ground cover. The foci of technogenic pollution of the soil cover represent an excess concentration of not one, but a whole complex of chemical elements, the cumulative impact of which was estimated by the value of the total concentration index (CIC) - the sum of excesses of accumulating elements over the background level. Depending on the values of this indicator, categories of pollution of territories are distinguished: permissible, moderately dangerous, dangerous and extremely dangerous.

B) Surface water.

C) green space.

Comprehensive assessment of the state of the environment

A) landscape structure of the territory. Currently, natural complexes have undergone significant anthropogenic changes. It is possible to single out a group of complexes where the urban development of the territory has practically not changed in terms of functioning, and sometimes anthropogenic intervention was even beneficial for the natural landscape. In other cases natural ecosystems degraded. The tracts of floodplains and partly terraces immediately adjacent to the riverbed have undergone the least transformation, where the native vegetation is replaced by maple plantations with an admixture of elm and willow. Over time, the plantations have lost their aesthetic appeal, and in addition, they have already reached physiological old age, which requires reconstruction measures. Besides high degree dense forest stand contributes to the worsening of the crime situation.

AT most the natural-territorial complexes occupied by residential and industrial buildings have undergone changes. The transformation of such complexes has an ambiguous urban planning effect. Vegetation is characterized by the replacement of its indigenous types in residential areas with cultural plantings with an age corresponding to the age of the building. In general, the state of such technogenic complexes satisfactorily, except for the territories occupied by industrial facilities, which caused the degradation of green spaces.

B) Analysis of the rehabilitation potential of the river. A comprehensive assessment of the ecological state of the territory is based on landscape biochemical studies of sustainability natural complexes to anthropogenic loads, assessment of the state of environmental components, as well as on the analysis of the urban development potential of the site under consideration and the general urban development situation in the urban areas adjacent to it.

To the negative natural factors includes the presence of steep slopes and flooded areas that are unstable to additional technogenic load. Negative technogenic factors should be considered high littering of the territory on separate sections, the impact of polluted and insufficiently treated effluents from residential areas, industrial zones and enterprises that affect the quality of water bodies. Consequently, the state of water bodies does not meet the requirements for cultural and community facilities. In addition, excessive atmospheric air pollution along highways is typical for almost the entire territory.

II. Water bodies, being natural and natural-technogenic elements of landscape-geochemical systems, in most cases are the final link in the runoff accumulation of most of the mobile technogenic substances. In landscape-geochemical systems, substances are transported from higher levels to lower hypsometric levels with surface and underground runoff, and vice versa (from lower to lower levels). high levels) - atmospheric flows and only in some cases, flows of living matter (for example, during the mass flight of insects from water bodies after the completion of the larval stage of development passing in water, etc.).

Landscape elements representing the initial, most highly located links (occupying, for example, local watershed surfaces), are geochemically autonomous and the entry of pollutants into them is limited, except for their entry from the atmosphere. Landscape elements that form the lower stages of the geochemical system (located on the slopes and in relief depressions) are geochemically subordinate or heteronomous elements that, along with the influx of pollutants from the atmosphere, receive part of the pollutants coming from the surface and groundwater from higher-lying links of the landscape-geochemical cascade. In this regard, the pollutants formed in the watershed due to migration into natural environment sooner or later they enter water bodies mainly with surface and ground runoff, gradually accumulating in them.

5 The main processes of water self-purification in a water body

Among the physical factors, the dilution, dissolution and mixing of incoming contaminants is of paramount importance. Good mixing and reduction of suspended particles concentrations is ensured by the fast flow of the rivers. It contributes to the self-purification of water bodies by settling to the bottom of insoluble sediments, as well as settling polluted waters. In zones with a temperate climate, the river cleans itself after 200-300 km from the place of pollution, and in the Far North - after 2 thousand km.

Self-purification of water bodies

Between the components of the aquatic ecosystem in the process of its functioning, there is a continuous exchange of matter and energy. This exchange has a cyclic nature of varying degrees of isolation, accompanied by the transformation of organic matter, in particular phenols, under the influence of physical, chemical and biological factors. In the course of transformation, complex organic substances can be gradually decomposed into simple ones, and simple substances can be synthesized into complex ones. Depending on the intensity of the external impact on the aquatic ecosystem and the nature of the processes, either the aquatic ecosystem is restored to the background conditions (self-purification), or the aquatic ecosystem passes to another stable state, which will be characterized by different quantitative and qualitative indicators of biotic and abiotic components. If the external impact exceeds the self-regulating capabilities of the aquatic ecosystem, it may be destroyed.

Self-purification of natural waters is carried out due to the involvement of substances coming from external sources in continuously occurring transformation processes, as a result of which the substances received are returned to their reserve fund.

The transformation of substances is the result of various simultaneously operating processes, among which physical, chemical and biological mechanisms can be distinguished. The value of the contribution of each of the mechanisms depends on the properties of the impurity and the characteristics of a particular ecosystem.

Biochemical self-purification.

Biochemical self-purification is a consequence of the transformation of substances carried out by hydrobionts. As a rule, biochemical mechanisms make the main contribution to the process of self-purification, and only when aquatic organisms are inhibited (for example, under the influence of toxicants), do physicochemical processes begin to play a more significant role. Biochemical transformation of organic substances occurs as a result of their inclusion in food webs and is carried out during the processes of production and destruction.

Primary production plays a particularly important role, since it determines the majority of intra-water processes. The main mechanism of new formation of organic matter is photosynthesis. In most aquatic ecosystems, phytoplankton is a key primary producer. In the process of photosynthesis, the energy of the Sun is directly transformed into biomass. The by-product of this reaction is free oxygen formed by the photolysis of water. Along with photosynthesis in plants, there are processes of respiration with the consumption of oxygen.

Chemical mechanisms of self-purification.

Photolysis is the transformation of molecules of a substance under the action of the light they absorb. Particular cases of photolysis are photochemical dissociation - the decay of particles into several simpler ones and photoionization - the transformation of molecules into ions. Of the total amount of solar radiation, about 1% is used in photosynthesis, from 5% to 30% is reflected by the water surface. The main part of solar energy is converted into heat and participates in photochemical reactions. The most effective part of sunlight is ultraviolet radiation. Ultraviolet radiation is absorbed in a water layer about 10 cm thick, however, due to turbulent mixing, it can also penetrate into deeper layers of water bodies. The amount of a substance subjected to photolysis depends on the type of substance and its concentration in water. Of the substances entering water bodies, humus substances are subject to relatively rapid photochemical decomposition.

Hydrolysis is an ion exchange reaction between various substances and water. Hydrolysis is one of the leading factors in the chemical transformation of organic substances in water bodies. The quantitative characteristic of this process is the degree of hydrolysis, which is understood as the ratio of the hydrolyzed part of the molecules to the total salt concentration. For most salts, it is a few percent and increases with increasing dilution and water temperature. Organic substances are also subject to hydrolysis. In this case, hydrolytic cleavage most often occurs through the bond of a carbon atom with other atoms.

One of the effective ways of self-purification is the transformation of the pollutant due to redox reactions when interacting with the redox components of the aquatic environment.

The possibility of Red-Ox transformations in the system is characterized by the value of its redox potential (Eh). The E h value of natural waters is affected by free O 2 , H 2 O 2 , Fe 2+ , Fe 3+ , Mn 2+ , Mn 4+ , H + , organic compounds and other "potential-setting components". In natural waters, E h usually ranges from +0.7 to -0.5V. Surface and ground waters saturated with oxygen are most often characterized by an E h interval from +0.150 to +0.700V. Studies show that in the processes of self-purification of natural water bodies from phenols, redox transformations with the participation of H 2 O 2 of natural origin and metal ions of variable valence present in water bodies play an important role. In natural water, the stationary concentration of H 2 O 2 is in the range of 10 -6 - 10 -4 mol/l. Hydrogen peroxide is formed due to photochemical and oxidative processes involving molecular oxygen in a homogeneous medium. Since the decay of H 2 O 2 is mainly determined by the catalytic amounts of metal ions and sunlight, its rate is almost independent of the initial concentration.

Physical mechanisms of self-purification.

Gas exchange at the "atmosphere-water" interface. Thanks to this process, substances that have a reserve fund in the atmosphere enter the water body and return these substances from the water body to the reserve fund. One of the important special cases of gas exchange is the process of atmospheric reaeration, due to which a significant part of oxygen enters the water body. The intensity and direction of gas exchange are determined by the deviation of the gas concentration in water from the saturation concentration C. The saturation concentration depends on the nature of the substance and the physical conditions in the water body - temperature and pressure. At concentrations greater than C, the gas escapes into the atmosphere, and at concentrations less than C s , the gas is absorbed by the water mass.

Sorption is the absorption of impurities by suspended matter, bottom sediments and surfaces of hydrobiont bodies. Colloidal particles and organic substances, such as phenols, which are in the undissociated molecular state, are sorbed most vigorously. The process is based on the phenomenon of adsorption. The rate of accumulation of a substance per unit mass of the sorbent is proportional to its unsaturation with respect to the given substance and the concentration of the substance in water, and is inversely proportional to the content of the substance in the sorbent.

Sedimentation and resuspension. Water bodies always contain a certain amount of suspended matter of inorganic and organic origin. Sedimentation is characterized by the ability of suspended particles to fall to the bottom under the action of gravity. The process of transition of particles from bottom sediments to a suspended state is called resuspension. It occurs under the action of the vertical component of the turbulent flow velocity.

Thus, sorption and redox processes play an important role in the self-purification of natural reservoirs.

The ecological state of water bodies is largely associated with the processes of self-purification - a natural reserve for restoring the original properties and composition of waters.
The main processes of self-cleaning lead to:

transformation (transformation) of pollutants into harmless or less harmful substances as a result of chemical and especially biochemical oxidation;
relative purification - the transfer of pollutants from the water column to bottom sediments, which in the future can serve as a source of secondary water pollution;
removal of pollutants outside the water body as a result of evaporation, release of gases from the water column or wind removal of foam.

The greatest role in the process of water self-purification is played by the transformation of pollutants. It covers non-conservative pollutants whose concentration changes as a result of chemical, biochemical and physical processes in water bodies. The non-conservative ones are mainly organic and biogenic substances. The intensity of the oxidation of a transformable pollutant depends primarily on the properties of this substance, water temperature, and the conditions for the supply of oxygen to the water body.

Temperature conditions can be estimated from the average water temperature for three summer months, which adequately reflects the conditions for the entire warm period (the water temperature on the rivers of Russia in the winter months remains almost the same, close to 0°C). According to this indicator, rivers and reservoirs are divided into three groups: with temperatures below 15°C, from 15 to 20°C and above 20°C.

The conditions for the supply of oxygen are determined mainly by the intensity of water mixing and the duration, which has a fairly close correlation with the summer.

The intensity of water mixing in rivers is estimated approximately, depending on the nature of the terrain through which they flow, and for lakes and reservoirs - by the shallow water coefficient g, depending on the water surface area and the average depth of the reservoir. According to these criteria, rivers and reservoirs are divided into 4 groups: with strong, significant, moderate and weak mixing. According to the combination of temperature and mixing conditions, 4 categories of conditions for the transformation of pollutants in surface waters are distinguished: favorable, medium, unfavorable and extremely unfavorable. The assessment of water self-purification based on these indicators is unacceptable either for the largest transzonal rivers (Volga, Yenisei, Lena, etc.), or for small rivers (with a basin area of less than 500 - 1000 km2), since the water temperature in them and the mixing conditions are very different from background values.

An important role in the self-purification of waters is also played by the physical process of diluting the content of pollutants, the concentration of which in river water decreases with an increase in water flow in the river. The role of dilution is not only to reduce the concentration of pollutants, but also to reduce the likelihood of poisoning (toxicosis) of aquatic organisms responsible for the biochemical degradation of pollutants. An indicator of the conditions for the dilution of pollutants is for a river its average annual water discharge, and for a reservoir - the total water discharge of the tributaries flowing into it. According to this indicator, all rivers and reservoirs are divided into 6 groups (with water flow from less than 100 to more than 10,000 m3/s). By combining the two most important conditions - the transformation of pollutants and the flow of water - it is possible to approximately estimate the conditions for self-purification of surface waters from pollutants and combine them into 5 categories: from "most favorable" to "extremely unfavorable". The conditions of self-purification, taking into account dilution for transzonal rivers, were calculated individually for individual sections of each river. The upper reaches of medium and large rivers, characterized by a weak dilution capacity, are categorized as rivers with "extremely unfavorable" self-purification conditions.
There are certain spatial regularities in the conditions for the transformation of pollutants in the surface waters of Russia. Thus, water bodies with "extremely unfavorable" conditions are located in low-lying tundra and forest-tundra areas. All deep-water lakes (Ladoga, Onega, Baikal, etc.) and reservoirs with especially slow water exchange belong to the same group. And territories with “favorable” conditions for transformation are confined to the Central Russian and Volga Uplands, the foothills of the North Caucasus.

Taking into account the dilution of pollution, most medium and almost all small rivers in Russia are characterized by "extremely unfavorable" conditions for self-purification. The “most favorable” conditions for self-purification are characteristic of the sections of the Ob, Yenisei, Lena and Amur rivers, which fall into the highest category of water content (more than 10,000 m3/s) at a water temperature in the middle range (15–20°C), as well as the lower reaches of the Volga with temperatures above 20°C. The same category of conditions have reservoirs: Volgogradskoe, Tsimlyanskoe, Nizhnekamskoe.

An analysis of the territorial difference in the conditions of self-purification of rivers and reservoirs makes it possible to approximately estimate the degree of danger of their pollution from the ingress of pollutants. This, in turn, can serve as the basis for setting the level of restrictions on wastewater discharges in cities and developing recommendations on the size of the reduction in the dispersed release of pollutants into surface waters.

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4 Sources of pollution of a water body depending on the landscape structure of the area

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4 Sources of pollution of a water body depending on the landscape structure of the area

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Self-purification of water bodies

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