Freshwater bodies perform several functions. On the one hand, rivers and lakes form an important part of the water cycle in nature. Freshwater bodies perform several functions. On the one hand, rivers and lakes form an important part of the water cycle in nature.

In the Arkhangelsk region, in addition to the listed functions, rivers play the role of transport routes along which various goods are transported. In the Arkhangelsk region, in addition to the listed functions, rivers play the role of transport routes along which various goods are transported.

Previously, timber rafting was carried out along the Onega, Northern Dvina and other rivers. With this method, a large number of logs were independently floated downstream during the spring flood. Thus, wood was delivered free of charge from logging areas to large sawmills in Arkhangelsk. This method of floating trees caused irreparable damage to nature. The bottom of the rivers where moth rafting was carried out was heavily clogged with rotting logs. Such rivers became unnavigable in the summer. As a result of wood rotting, there was a low oxygen content in the water. Previously, timber rafting was carried out along the Onega, Northern Dvina and other rivers. With this method, a large number of logs were independently floated downstream during the spring flood. Thus, wood was delivered free of charge from logging areas to large sawmills in Arkhangelsk. This method of floating trees caused irreparable damage to nature. The bottom of the rivers where moth rafting was carried out was heavily clogged with rotting logs. Such rivers became unnavigable in the summer. As a result of wood rotting, there was a low oxygen content in the water.

Despite its high economic efficiency, this method of transporting wood caused great harm to the environment. Therefore, it has now been abandoned. Nowadays, wood is transported along rivers in the form of large rafts. In this case, there is no loss of logs, and therefore, rivers and the sea are not polluted. Despite its high economic efficiency, this method of transporting wood caused great harm to the environment. Therefore, it has now been abandoned. Nowadays, wood is transported along rivers in the form of large rafts. In this case, there is no loss of logs, and therefore, rivers and the sea are not polluted.

Northern rivers are famous for their abundance of diverse fish. They are inhabited by whitefish, char, omul, and herring. In the spring, the valuable commercial fish northern salmon, or salmon, comes to the rivers flowing into the White and Barents Seas to spawn. Currently, the number of this species has greatly decreased due to poaching. To preserve salmon, the state regulates fishing standards for special fishing teams. But sometimes residents catch salmon with nets on their own without permission from fisheries conservation organizations; in this regard, the problem of poaching in the northern rivers is especially acute. Northern rivers are famous for their abundance of diverse fish. They are inhabited by whitefish, char, omul, and herring. In the spring, the valuable commercial fish northern salmon, or salmon, comes to the rivers flowing into the White and Barents Seas to spawn. Currently, the number of this species has greatly decreased due to poaching. To preserve salmon, the state regulates fishing standards for special fishing teams. But sometimes residents catch salmon with nets on their own without permission from fisheries conservation organizations; in this regard, the problem of poaching in the northern rivers is especially acute.

SALMON is an anadromous fish of the salmon family. Length up to 150 cm, weighs up to 39 kg. SALMON is an anadromous fish of the salmon family. Length up to 150 cm, weighs up to 39 kg. After feeding in the sea, it migrates to rivers to breed. There are two known races of salmon in the White Sea: autumn and summer. The Northern Dvina salmon run begins in the spring and continues until freeze-up.

The main negative impact of humans on the condition of rivers and lakes is their pollution by chemical waste. The Northern Dvina is the most polluted. The largest pulp and paper mills in Europe are located on this river. One of them is located near Kotlas, in the city of Koryazhma, and the other two are in Novodvinsk and Arkhangelsk. The main negative impact of humans on the condition of rivers and lakes is their pollution by chemical waste. The Northern Dvina is the most polluted. The largest pulp and paper mills in Europe are located on this river. One of them is located near Kotlas, in the city of Koryazhma, and the other two are in Novodvinsk and Arkhangelsk.

The total pollution of the Northern Dvina is so high that in summer it is not recommended to swim in the river within the city of Arkhangelsk. The problem of water pollution in Arkhangelsk is particularly acute, since in this city the river is the only source of drinking water. To control the quality of fresh water, the state has developed a Water Code. The Law of the Russian Federation “On the Protection of the Natural Environment” has a separate article on the protection of fresh waters. In Russia, maximum permissible concentrations and maximum permissible standards for discharges of harmful substances from industrial enterprises have been developed. The General Directorate of Natural Resources and Environmental Protection is responsible for the implementation of these laws and for monitoring the quality of wastewater. The total pollution of the Northern Dvina is so high that in summer it is not recommended to swim in the river within the city of Arkhangelsk. The problem of water pollution in Arkhangelsk is particularly acute, since in this city the river is the only source of drinking water. To control the quality of fresh water, the state has developed a Water Code. The Law of the Russian Federation “On the Protection of the Natural Environment” has a separate article on the protection of fresh waters. In Russia, maximum permissible concentrations and maximum permissible standards for discharges of harmful substances from industrial enterprises have been developed. The General Directorate of Natural Resources and Environmental Protection is responsible for the implementation of these laws and for monitoring the quality of wastewater.

Another source of pollution of rivers and lakes is domestic wastewater. Most of the large cities in the Arkhangelsk region are located on the banks of large rivers. Therefore, large amounts of insufficiently treated wastewater can end up in rivers and then into the sea. To maintain high water quality in the rivers of the Arkhangelsk region and preserve the diverse flora and fauna, industrial enterprises must comply with pollutant emission standards, and the population must comply with environmental laws and take care of the wealth that nature has awarded. Another source of pollution of rivers and lakes is domestic wastewater. Most of the large cities in the Arkhangelsk region are located on the banks of large rivers. Therefore, large amounts of insufficiently treated wastewater can end up in rivers and then into the sea. To maintain high water quality in the rivers of the Arkhangelsk region and preserve the diverse flora and fauna, industrial enterprises must comply with pollutant emission standards, and the population must comply with environmental laws and take care of the wealth that nature has awarded.

Literature Ecology of the Arkhangelsk region: Textbook for students in grades 9-11 of secondary schools / Ed. Ed. Batalova A. E., Morozova L. V. - M.: Publishing house - Moscow State University, 2004. Geography of the Arkhangelsk region (physical geography) 8th grade. Textbook for students. / Edited by Byzova N.M. - Arkhangelsk, publishing house of the Pomeranian International Pedagogical University named after M.V. Lomonosov, 1995. Regional component of general education. Biology. - Department of Education and Science of the Administration of the Arkhangelsk Region, 2006. PSU, 2006. JSC IPPC RO, 2006

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The main sources of water pollution are domestic wastewater and industrial wastewater. Surface runoff (storm water) is a variable factor in the pollution of water bodies in terms of time, quantity and quality.

Pollution of water bodies also occurs with waste from water transport and timber rafting. According to the “Sanitary norms and rules for the protection of surface waters from pollution” (No. 4630-88), reservoirs and drains (water bodies) are considered polluted if the composition and properties of the water in them have changed under the direct or indirect influence of industrial activities and household use of the population. The criterion for water pollution is deterioration in quality due to changes in organoleptic properties and the appearance of substances harmful to humans, animals, birds, fish, food and commercial organisms, as well as an increase in water temperature, changing the conditions for the normal functioning of aquatic organisms.

Water use is distinguished into two categories: the first category includes the use of a water body as a source of centralized or non-centralized household and drinking water supply, as well as for water supply to food industry enterprises; to the second category - the use of a water body for swimming, sports and recreation of the population, as well as the use of water bodies located within populated areas. Water use points of the first and second categories are determined by the bodies and institutions of the sanitary and epidemiological service with mandatory consideration of official data on the prospects for using the water body for drinking water supply and cultural and everyday needs of the population.

When discharging wastewater within a city (or any locality), the first point of water use is this city (or locality). In these cases, the requirements established for the composition and properties of water in a reservoir or stream must apply to the wastewater itself.

The main elements of water and sanitary legislation are hygienic standards or MAC - maximum permissible concentrations at which substances do not have a direct or indirect effect (if exposed to the body throughout life) and do not worsen the hygienic conditions of water use. MPCs serve as the basis for preventive and ongoing sanitary supervision. The limiting sign of harmfulness, according to which the traffic rules are established: sanitary-toxicological (s.-t.), general sanitary (general) and organoleptic (org.). The limiting sign of harmfulness is taken into account when several harmful substances are present simultaneously. If several substances of hazard classes I and II are present in water, the sum of the ratios of these concentrations (C1, C2. Cn) of each of the substances in the water body to the corresponding maximum permissible concentrations should not exceed one:

In accordance with the classification of chemical substances according to the degree of danger, they are divided into 4 classes: Class I - extremely dangerous, Class II - highly dangerous, Class III - dangerous, Class IV - moderately dangerous. The classification is based on indicators characterizing the degree of danger to humans of substances that pollute water, depending on general toxicity, cumulativeness, and the ability to cause long-term side effects.

The composition and properties of water in a water body at points of household, drinking and cultural water use should not exceed the standards presented in Table. 16-18; water bodies for fishing purposes - in table. 19 (standards approved on October 24, 1983; No. 2932-83-04.07.86; No. 42-121-4130-86).

Table 16. Maximum concentrations of harmful substances in water of water bodies for domestic, drinking and cultural water use

*" Within the limits calculated based on the content of organic substances in the water bodies and according to the indicators of the military-industrial complex and dissolved oxygen.

*2 Harmful if absorbed through the skin.

*3 For inorganic compounds

*4 Taking into account the oxygen regime for winter conditions.

*5 MPC of phenol - 0.001 mg/l - indicated for volatile phenols that give water a chlorophenolic odor during chlorination (test chlorination method); MPC refers to water bodies for domestic and drinking water use, subject to the use of chlorine for water disinfection during its purification at water supply facilities or when determining the conditions for the discharge of wastewater subjected to disinfection with chlorine. In other cases, the content of the amount of volatile phenols in the water of water bodies is allowed at a concentration of 0. 1 mg/l.

*6 This also means fluorine in compounds.

*7 Taking into account the chlorine absorption capacity of water bodies.

*8 Simple and complex cyanides (with the exception of cyanoferrates) calculated as cyanogen.

Table 17. Approximate permissible levels (TAL) of substances in water of water bodies for domestic, drinking and cultural water use

Table 18. General requirements for the composition and properties of water in water bodies at points of domestic, drinking and cultural water use

Table 19. General requirements for the composition and properties of water in water bodies used for fishing purposes

Sanitary protection of small rivers. High anthropogenic load causes a potential risk of deterioration of water quality and disruption of water use conditions in certain sections of small rivers (watercourses up to 200 km long), increases the risk of intestinal infections and intoxications among the population due to the flow of wastewater containing pathogenic microorganisms, pesticides, and heavy salts. metals, etc.

Small rivers usually have low water flow, low water supply and depth, and low flow speed, which creates relatively unfavorable conditions for mixing and, accordingly, dilution of pollutants. Small rivers, being the initial link of the river network, influence the entire hydrographic network; it is possible to spend a significant part (of the total runoff) on local economic needs and retain it in watersheds (reservoirs, ponds).

The formation of reservoirs and ponds has a positive effect (increase in volume, natural settling and aeration of water). At the same time, a decrease in the flow of water bodies under the conditions of economic activity can negatively affect the intensity of self-purification processes, worsen the dilution of pollution, be accompanied by “blooming” with a deterioration in the organoleptic properties of water, and during the period of algae dying off - the appearance of toxic products of their decomposition in the water.

The main tasks of state sanitary supervision are: characterizing the state of the river and assessing water quality; identification of main sources of pollution; justification of hygienic measures to protect small rivers from pollution and ensure favorable conditions for water use by the population; control over their implementation.

From a hygienic point of view, special attention should be paid to determining the water quality of small rivers at control points, which should be installed in accordance with the existing and planned use of the river, the presence of a source of pollution upstream from the point of water use: in areas used for domestic and drinking water supply; within the boundaries of a populated area; in places of mass recreation of the population. Observation sites should be located 1 km upstream from points of domestic and drinking water use and places of public recreation (with the exception of cases when the sanitary situation requires closer placement). For each site it is necessary to have information about the distance from the nearest source of pollution and the average water consumption per year of 95% supply.

The sanitary characteristics are given on the basis of: the results of laboratory studies of water quality at control sites; data on sources of pollution and composition of wastewater; results of analyzes of wastewater entering reservoirs in order to determine compliance of the discharge with the requirements of “Sanitary norms and rules for the protection of surface waters from pollution” No. 4630-88; obtaining the necessary information from the bodies and institutions of the Ministry of Water Resources, the State Hydrometeorological Committee, and other institutions that monitor the use and protection of water; survey of the population and analysis of citizens' statements about the conditions of water use.

In areas of recreational water use, water is examined 2 times before the start of the swimming season and 2 times monthly during the swimming season; analyzes can be limited to organoleptic (smell, color, floating impurities, film) and bacteriological (coli index) indicators.

In cases of centralized household and drinking water use, the frequency of sampling and the list of water quality indicators are established in accordance with the requirements of GOST 2761-84 “Sources of centralized household and drinking water supply. Hygienic, technical requirements and selection rules" (at least 12 times a year monthly).

Within populated areas, the frequency of sampling is established by the local sanitary and epidemiological service authorities, depending on the sanitary and epidemiological situation.

Preventive sanitary supervision over the sanitary condition of small rivers is carried out when considering projects of sanitary protection zones for sources of centralized household and drinking water supply and coastal strips (zones), norms of maximum permissible discharges (MPD) and other design materials submitted for approval.

When assessing the sanitary condition of small rivers and monitoring the implementation of measures for their protection, first of all, the main (priority) types of their pollution should be taken into account; drainage from livestock complexes, farms, poultry farms, grazing and watering areas for livestock; surface runoff from residential, agricultural and industrial areas, and in the southern regions - return and collector-drainage waters; wastewater from health care facilities; drainage in places of mining (ore, coal, oil), discharge of blowing water from circulating water supply systems of large industrial facilities, wastewater from dry cleaners, etc.; industrial wastewater in areas where territorial production complexes, individual large industries and industrial hubs are located; use of sections of small rivers by the population for recreational purposes. The discharge of wastewater from livestock (pig) complexes and poultry farms into small rivers without complete biological treatment is prohibited (for details, see “Guidelines for the hygienic assessment of small rivers and sanitary control over measures for their protection in places of water use” No. 3180-84).

Sanitary protection of coastal sea waters. According to the “Rules for the sanitary protection of coastal waters of the seas” (No. 121074; see also “Guidelines for the hygienic control of marine pollution” No. 2260-80), the coastal protected area of ​​the sea is determined by the boundaries of the area of ​​actual and future marine water use of the population and two belts of the zone sanitary protection (SPO): area of ​​direct water use - areas of the sea used for cultural, domestic, health and medical purposes with a width towards the sea of ​​at least 2 km; zone I ZSO - to prevent exceeding standard indicators of microbial and chemical water pollution within the limits of actual and future water use from organized wastewater discharges (along the coastal length and width towards the sea at least 10 km from the border of the water use area); zone II ZSO - to prevent water pollution in the water use area and zone I ZSO from the sea from sea vessels and industrial facilities for mining. The boundaries of this belt are determined towards the sea by the boundaries of territorial waters for internal and external seas in accordance with the requirements of international conventions adopted by the USSR.

It is prohibited to discharge wastewater into the sea, which can be eliminated through rational technology, maximum use in recycling and reuse water supply systems, or through the installation of waste-free production; containing substances for which maximum permissible concentrations (MACs) have not been established. Discharges of treated industrial and domestic wastewater (including ship water) within the boundaries of the water use area are prohibited. Requirements for the composition and properties of sea water in the water use area of ​​the 1st and 1st zones of the WSO, see table. 20.

In public bathing areas, an additional indicator of pollution is the number of staphylococci in the water; signal value is an increase in their number by more than 100 per 1 liter (in places of water intakes of swimming pools with sea water, the number of bacteria of the E. coli group and enterococci, respectively, is no more than 100 and 50 per 1 liter).

For the first zone of the Western Zone, the coli index of wastewater is no more than 1000 with a concentration of free chlorine of at least 1.5 mg/l. When discharging wastewater from the shore beyond the boundaries of the first zone of the Western Zone, microbial pollution of sea water at the border of the first and second zones of the zone should not exceed 1 million according to the colon index.

Maximum permissible concentrations for harmful substances apply to water intakes for drinking water and recreational medical use of sea waters and areas of marine water use (temporarily until standards are developed for coastal sea waters).

For coastal areas of seas with specific hydrological conditions and sanitary, hydrophysical and hydrological features of the area that are unsatisfactory from a hygienic point of view, causing stagnation or concentration of pollution in coastal waters, the requirements and standards for the first zone of the SSS should be attributed to wastewater without taking into account possible mixing and dilution their sea water.

To prevent pollution of the coastal protected area of ​​the sea from ships in ports, port points and from ships stationed in roadsteads, it must be possible to discharge wastewater (through drainage devices, sewage vessels, etc.) into the citywide

Table 20. Requirements for the composition and properties of sea water in the water use area of ​​the 1st and 1st zones of the Western Socialist Zone

sewerage; solid waste, waste and garbage must be collected in special containers on board the ship and delivered ashore for subsequent disposal and neutralization.

To clean the sea from oil (petroleum products), ports and port points must have equipment - special mechanisms, ships or craft that ensure the collection of oil and subsequent disposal of oil residues.

When exploring and developing the resources of the continental shelf, it is necessary to provide for protective measures to prevent pollution of the shelf and the aquatic environment above it by industrial and household production waste.

Conditions for the discharge of fresh water. Requirements for the conditions for the discharge of wastewater into water bodies apply to the discharge of all types of industrial and domestic wastewater from populated areas (urban, rural)
and separate residential and public buildings, including mine water, waste water from water cooling, hydro-ash removal, oil production, hydraulic stripping operations, waste water from irrigated and drained agricultural areas, including those treated with pesticides, and other waste water from any objects, regardless of their departmental affiliation (the requirements also apply to storm drainage).

The conditions for the discharge of wastewater into water bodies are determined taking into account the degree of possible mixing and dilution of wastewater with the water of a water body on the way from the place of wastewater discharge to the design (control) site of the nearest points of economic, drinking and fishery water use" and the water quality of reservoirs and watercourses above the place projected wastewater discharge. Taking into account the processes of natural self-purification of water from substances entering it is allowed if the self-purification process is sufficiently pronounced and its patterns have been sufficiently studied.

Sanitary supervision of sewage treatment plants. Sewage is understood as a set of sanitary measures and engineering structures that ensure the collection and disposal of wastewater, its purification, neutralization and disinfection. During mechanical treatment, the liquid and solid phases of wastewater are separated: grates, sand traps, settling tanks, septic tanks, two-tier settling tanks. The liquid part of wastewater is subjected to biological treatment (natural or artificial): natural - in filtration fields, irrigation fields, in biological ponds; artificial - in biofilters, aeration tanks. Sludge (sewage sludge) treatment is carried out on sludge beds, in digesters or in mechanical dewatering and thermal drying plants.

Sanitary supervision includes inspection of treatment facilities and assessment of the effectiveness of their operation through systematic visits to the facilities, laboratory control, and identification of the impact on the sanitary condition of the reservoir. The dimensions of land plots for structures and sewers during artificial biological treatment are given in Table. 21.

Table 21. Size of land plots for sewerage treatment facilities during artificial treatment

For the dimensions of sanitary protection zones between sewage treatment plants and residential areas or food enterprises, see SN 245-71.

The territory of treatment facilities must be landscaped, landscaped, illuminated and fenced. Facilities for mechanical wastewater treatment include screens, sand traps, and settling tanks.

When inspecting the grates, it is important to pay attention to the timely removal of retained substances from the grates (clogging of the grates is detected externally by the amount of waste on the grate and by raising the level of waste liquid in front of the grate by 5-8 cm).

Correct operation of the sand trap is ensured by timely removal of sediment; When sediment accumulates, suspended substances are removed from the sump.

Sedimentation tanks are used for preliminary wastewater treatment (if biological treatment is required) or as independent structures (if only mechanical impurities need to be separated from wastewater). Depending on their purpose, settling tanks are divided into primary and secondary. Primary ones are installed before biological wastewater treatment facilities, secondary ones - after these structures. Based on their design characteristics, settling tanks are divided into horizontal, vertical and radial.

Primary settling tanks can provide a liquid clarification effect of up to 60% (usually within 30-50%).

Facilities for treating sewage sludge include septic tanks, settling tanks and clarifiers, digesters, digesters, sludge beds. Septic tanks are structures in which the clarification of waste liquid, long-term storage and decomposition of the fallen sludge occur simultaneously (the sludge is stored from 6 to 12 months and under the influence of anaerobic microorganisms are destroyed, insoluble organic substances are converted partly into a gaseous product, partly into soluble mineral compounds); The waste liquid is clarified for 1-3 days, which provides a relatively high clarification effect. Two-tier settling tanks are used for treatment plants with a capacity of up to 10,000 m3/day. The sediment that falls into the sludge chamber is fermented under the influence of anaerobic bacteria with the formation of methane, carbon dioxide and hydrogen sulfide.

Normally, the process of anaerobic destruction of organic substances occurs in an alkaline environment (pH 8.0). The acidity of the environment serves as an indicator of the normal operation of these structures. The process of rotting sediment takes a long time (60-180 days). The sediment is considered technically mature when it easily releases moisture when dried and does not emit a bad odor. It rots domestic water sludge well.

The clarifier-digester consists of a clarifier with natural aeration and a digester located concentrically around it. The digester is a cylindrical or rectangular reinforced concrete tank with a conical bottom. In digesters, the gas resulting from fermentation is collected in a bell located at the top of the gas-tight ceiling, from where it is removed for use. To speed up the fermentation process, various techniques are used, such as heating the sludge and mixing it. The fermented sludge has high moisture content. There are various techniques for drying sludge; the most common is drying on sludge beds. Silt pads consist of graded plots of land (maps) surrounded on all sides by earthen ridges.

When examining sludge sites, it is necessary to pay attention to the general operating mode of the sites (number of maps) - the thickness of the layer of accepted load, drying periods, the degree of drying, the system for removing and using sediment, the absence or presence of overloading of sites with sediment. The silt layer on the maps should be 20-30 cm in summer and 10 cm below the height of the rollers in winter. When overloaded, the drying period is shortened, the soil of the sites becomes silted, and working conditions for removing sediment from the sites and removing it are difficult.

Agricultural irrigation fields (AIF) are intended for round-the-clock and year-round neutralization of wastewater, which is used for irrigation and fertilization of agricultural crops. According to the “Sanitary Rules for the Construction and Operation of Agricultural Irrigation Fields” (No. 3236-85), it is not allowed to establish a ZPO on the territory of the 1st and 2nd zones of the sanitary protection zone for sources of centralized household and drinking water supply; in the area of ​​pinching out of aquifers and fractured rocks and karsts; within the resort sanitary protection district; when the depth of groundwater from the ground surface is less than 1.25 m on sandy and sandy loam soils and less than 1 m on loamy and clayey soils.

To collect drainage water and then use it for irrigation, it is necessary to provide storage ponds.

A sanitary protection zone is established between populated areas and the territory of the ZPO, the width of which depends on the irrigation method and should be (at least): for subsurface irrigation - 100 m; with surface irrigation - 200 m; when sprinkling: a) with short-stream devices - 300 m, b) with medium-stream devices - 500 m, c) with long-stream devices - 750 m. The sanitary protection zone to the main roads must be at least 100 m, including the right-of-way.

Along the borders of irrigated fields on the side of populated areas, it is planned to construct sanitary protective forest belts with a width of at least 15 m, and along highways - 10 m.

Filtration fields are used to purify the liquid phase of wastewater. When choosing a territory for their location, they are guided by the same rules (see above, No. 3236-85). The most suitable soils for filtration fields are sand and sandy loam.

During sanitary supervision of the operation of irrigation fields and filtration fields, attention should be paid to the conditions for filtering waste liquid through the soil (ensuring a normal filtration rate): frequency of waste liquid injection, correct site planning, systematic plowing of the site soil, timely cutting of furrows, weed control, absence of overloading of fields and their individual sites (maps) with waste liquid. It is important to maintain the trays and channels that supply liquid to the fields and individual field maps, which must be free from blockages and overgrown grass. Valves for switching the liquid supply to different sites must be in good working order. The roller system must reliably protect against spillage of wastewater into the area surrounding the map. It is necessary to systematically monitor the increase in groundwater levels under the influence of irrigation.

Biological filters consist of an impervious base, drainage, side walls, filter media and distribution devices. The biofilter consists of a container; filter load; a distribution device that ensures uniform (at small intervals) irrigation of the surface of the filter media; bottom with drainage, through which purified water is removed and through which the air necessary for the oxidation process enters the biofilter body. The filter media material must be sufficiently porous, durable and resistant to destruction from mechanical and chemical influences (boiler slag, certain types of coal, coke, gravel, crushed hard rock and well-burnt expanded clay). Passing through the filter media of the biofilter, contaminated water leaves in it due to adsorption suspended and colloidal organic substances (not settled in the primary settling tanks), which create a biofilm populated by microorganisms. Biofilm microorganisms oxidize organic substances. Thus, organic substances are removed from wastewater, and the mass of active biological film in the body of the biofilter increases (spent and dead film is washed off by flowing wastewater and removed from the body of the biofilter). The cleaning effect of biofilters is very high (BODb 90% or more). Laboratory monitoring of the operation of biofilters is carried out by taking samples of incoming and outgoing waste liquid (average samples taken in separate portions every 30 minutes for 4-6 hours). They determine temperature, appearance, smell, transparency, insoluble substances and their ash content, oxidability, BOD, stability, dissolved oxygen, ammonium nitrogen, nitrates, nitrites, chlorides. With efficient filters, the waste liquid becomes transparent and the turbidity disappears; the fecal odor of the water changes to earthy; transparency increases to 20-30 cm according to Snellen; the amount of insoluble substances decreases slightly, since the water supplied as a biofilter has already been settled; oxidation drops by 60-80%; biochemical oxygen demand decreases by 80-95%; relative stability increases to 80-90%; ammonium nitrogen almost completely turns into nitrate nitrogen, and nitrites are found in small quantities (up to fractions of a milligram per 1 liter); dissolved oxygen appears in an amount of 3-8 mg/l; the concentration of chlorides in the waste liquid does not change.

The aerofilter is intensively blown from the bottom up with air, so the oxidation process is more intense than in biofilters (approximately 2 times), and, therefore, the amount of purified waste liquid in this case can be significantly higher. Depending on the climate zone and the capacity of the structure, bio- and aerofilters should be placed in heated rooms or unheated rooms of lightweight construction. When monitoring the operation of bio- and aerofilters, it is necessary to monitor the uniform distribution of waste liquid over the surface of the biofilter, the good condition of the loading material, and the cleanliness of the drainage space under the filter and discharge trays. In case of surface siltation of the filter material and stagnation of water on the surface of the filter, the wetlands should be loosened and washed with a stream of water under pressure.

An aeration tank is a reservoir in which a mixture of activated sludge and purified waste liquid moves slowly (constantly mixed with compressed air or special devices). Activated sludge is a biocenosis of microorganisms - mineralizers, capable of sorbing on their surface and oxidizing organic substances of waste liquid in the presence of atmospheric oxygen. The mixture of waste liquid with activated sludge must be aerated throughout the entire length of the aeration tank (with blowers). When monitoring the operation of the aeration tank, it is necessary to monitor, first of all, compliance with the duration of residence of the waste liquid in it, the content of the required amount of activated sludge and the air supply regime over the entire area of ​​the aeration tank, timely removal and treatment of excess activated sludge. Laboratory monitoring of the efficiency of the aeration tank is carried out using the same indicators as for biological filters.

Secondary settling tanks are designed to retain biological film from waste liquid after biofilters or activated sludge coming with liquid after aeration tanks. In addition, they are used as contact tanks when chlorine solution is added to wastewater. Secondary settling tanks, which are technologically connected structures with aeration tanks, serve only to separate activated sludge from wastewater purified in the aeration tank. The duration of settling of the sludge mixture in the secondary settling tank is 1-0.5 hours (the sludge is completely removed from the secondary settling tank). It is necessary to maintain the uniformity of the flow and exit of wastewater from the secondary settling tank (less than 1 mg/l).

Biological, or treatment, ponds are used as independent treatment devices or as facilities for the post-treatment of wastewater pre-treated in biological structures (biofilters, aeration tanks). In the first case, wastewater, having passed through settling tanks, is diluted before entering the ponds with 3-5 volumes of technical or household drinking water. When operating ponds, the load on them is assumed to be: for settled wastewater without dilution - up to 250 m3/ha per day, for biologically treated wastewater - up to 500 m3/ha per day. The average depth in biological ponds should be no more than 1 m and no less than 0.5 m. In the spring, before putting biological ponds into operation, their bottom is plowed, the ponds are filled with wastewater and kept until ammonia nitrogen almost completely disappears from it. The period of “ripening” of ponds for the central zone of the USSR is at least 1 month. In the fall, after the biological ponds are finished operating, the water is released from them (in the winter, biological ponds are operated by freezing ice on them).

Since wastewater from any populated area must be regarded as containing pathogenic microbes, disinfection must be provided in all cases of artificial treatment. Currently, wastewater disinfection is provided after both mechanical and biological treatment. Disinfection is carried out with liquid chlorine: the dose of active chlorine after mechanical cleaning is at least 30 mg/l, after incomplete biological cleaning - 15 m/l, after complete artificial biological cleaning - 10 mg/l. At small treatment plants with a capacity of up to 1000 m3/day, the use of bleach is allowed.

Chlorination of waste liquid is carried out in special contact tanks, arranged like horizontal or vertical settling tanks. The duration of contact of chlorine with the liquid must be at least 30 minutes, so if purified water passes from the treatment station to the reservoir for 30 minutes or more, then contact tanks do not need to be installed. The content of residual active chlorine in the waste liquid of at least 1.5 mg/l serves as an indicator of the sufficient depth of its disinfection.

When monitoring the operation of a chlorination plant, it is necessary to take into account the thoroughness of mixing chlorine with waste liquid, the uniformity of chlorine supply, and the contact time of chlorine with waste liquid. Sediment that accumulates at the bottom of contact pools must be removed after 2-3 days. For each installation, instructions on chlorination of wastewater, storage of chlorine and safety precautions must be drawn up.

When deciding on the issue of sewerage, treatment and disposal of wastewater from an industrial enterprise, the possibility and feasibility of using wastewater in the recycling and reuse water supply system of enterprises or workshops should be considered, depending on specific local conditions.

Drawing up a project for sewerage, treatment, neutralization and disinfection of wastewater should be based on taking into account the quantity, composition and regime of wastewater disposal; sanitary condition of the water body in the area of ​​the designed facility; sanitary situation above and below the wastewater discharge of this facility; use of the water body for domestic and drinking water supply and cultural and everyday needs of the population and for fishing and other purposes at present and in the future. In the absence of established standards, before the start of design, water users must ensure that the necessary research is carried out to study the degree of harmfulness of the substances contained in wastewater and justify the maximum permissible concentrations for them in the water of water bodies according to the nature and category of water use.

Sanitary protection of water bodies from pollution by wastewater from large livestock and poultry farms. Drains from livestock farms are hazardous from a sanitary and epidemiological point of view (they contain typical and atypical cultures of microbes of the Salmonella group, enteropathogenic Escherichia coli, Proteus, Pseudomonas aeruginosa, etc.). The total amount of manure runoff from livestock complexes and industrial farms is calculated taking into account the volume of excrement (feces, urine) of animals; water for their removal from production premises; water spent on washing floors and equipment; water leaks from drinking bowls; hourly and daily coefficient of uneven water flow.

The approximate daily amount of manure waste generated at a pig farm from one animal is 40 liters, and from a pig farm for 108 thousand animals per year - 3000 m3, for 54 thousand animals per year - 1500 m3. When animals are kept in stalls and pastures, the amount of manure is reduced by 50% due to loss on pastures and by 12% on walking areas. The volume of waste liquid from milking platforms is 62 liters per head (the proportion of excrement in it is 8-10%).

Manure runoff from livestock farms can be a factor in the transmission of more than 100 infectious diseases (brucellosis, tuberculosis, etc.). From the liquid fraction of pig manure, from 11 to 21 strains of enteropathogenic Escherichia coli and from 22 to 59 strains of salmonella are isolated (see also Chapter 17).

The epidemic danger of manure runoff from livestock farms consists not only of the presence of pathogenic microorganisms and their high concentration, but also of long survival times. The survival rate, for example, of Brucella in undiluted manure at a temperature of 25 ° C is 20-25 days, and that of Mycobacterium tuberculosis is 475 days. As the moisture content of manure increases, the survival time of pathogenic bacteria increases. Pig manure and wastewater may contain viable eggs and larvae of helminths that are dangerous to humans. In warm weather, when manure waste is stored in manure storage facilities, the survival rate of helminth eggs reaches 4 months. In cold weather, even a longer period of holding wastewater does not ensure its complete deworming. 80-90% of viable helminth eggs (ascaris) remain in manure and manure drains.

Collection and removal of manure and manure waste from livestock buildings is carried out using mechanical, pneumatic, hydraulic (flush, gravity) methods. The gravity system is used for keeping animals without bedding on slatted floors. Manure channels must have reliable waterproofing. The settling-tray system is recommended for keeping animals on slatted floors without bedding, which provides for the periodic accumulation of animal excrement in manure channels (7-14 days) when they are filled with water to a height of 15=20 cm. With a flush system, daily use of water is provided for the removal of animal excrement from manure channels.

The most appropriate way to transport manure and manure waste from livestock complexes and industrial farms to storage and processing sites is to supply them through a closed pipeline. In some cases, it is allowed to use mobile transport to transport liquid manure to the place of application to the soil, for which appropriate justifications must be given in the projects. For storage and dewatering of litter manure, non-buried waterproof areas or containers with a depth of 1.8-2 m are provided.

Facilities for storing liquid manure and manure waste must meet the following requirements:

Ensure prevention of the spread of infectious diseases (“interim” quarantine);

Avoid infiltration into soil and groundwater,

The total capacity of manure storage facilities should be designed for a period that ensures the release of manure from pathogenic microorganisms and helminth eggs (at least 6 months) from the moment of receipt of their last portions.

The quarantine period for manure must be at least 6 days, which corresponds to the incubation period of infectious diseases.

Manure infected with persistent pathogenic microorganisms in quarantine containers (pathogens of anthrax, plague, rabies, tuberculosis, etc.) is burned after pre-moistening with disinfectant solutions. Disinfection of liquid manure with formaldehyde during an epizootic should be carried out in quarantine containers, based on the rate of reagent consumption and contact time: for manure infected with salmonella and colibacteria - from 0.04 to 0.16% of the volume of manure with a contact time of 24 hours and homogenization for 3 hours; for manure infected with pathogens of foot-and-mouth disease and Aueszky's disease - 0.3% of the volume of manure with a contact time of 72 hours and homogenization for 6 hours.

Mechanical processing of liquid manure is used to separate solid particles from its mass.

Currently, manure and manure runoff generated on livestock complexes and farms are mainly used to fertilize and irrigate agricultural fields. The main hygienic requirements aimed at ensuring complete neutralization of manure are: the presence of a sufficient number of areas for disposal, favorable soil-climatic, hydrological and hydrogeological conditions.

Irrigation fields are established on chernozem, sandy, sandy loam, loamy soils and drained peat bogs. The groundwater level must be at least 1.5 m. If the groundwater depth is less than 1.5 m, a drainage system is necessary. Drainage water is prohibited from being discharged into water bodies (it is recommended to reuse it for irrigation or diluting manure and slurry before applying it to fields).

In cases where soil methods cannot be applied, it is recommended to install artificial biological wastewater treatment facilities, followed by additional treatment in biological ponds and discharge into water bodies or use them for irrigation. To ensure the effective operation of artificial biological treatment facilities, the dose of activated sludge should be at least 10-12 g/l. The BODb load on sludge should not exceed 100 mg/g sludge per day. The silt index of such sludge is 60-120 mg/g. The increase in activated sludge is 40% of the COD at a humidity of 96-97%.

The solid fraction of manure (with a moisture content of no more than 70%) is composted or piled on special waterproofed sites that have a slope towards drainage ditches (the sites are buried in the ground up to 1 m). The liquid released from the solid fraction of manure, together with precipitation, is sent to a slurry collector for further processing.

The holding time of the solid fraction of manure in piles is at least 6-8 months. It is recommended to cover the piles with sawdust, peat or soil with a thickness of 15-20 cm in summer and 30-40 cm in winter. This ensures that the temperature in all layers of the piles rises to 60 ° C, which is destructive for pathogenic microflora and helminth eggs. After neutralization, the composts are transported to fields as fertilizer.

To dilute manure and manure runoff on irrigation fields, it is necessary to have reliable water sources (drainage water from irrigation fields can be used). In irrigation fields, measures must be taken to prevent manure and manure runoff from entering open water bodies (installation of rollers, storage ponds, drainage and bypass canals, etc.). The capacity of storage ponds is determined taking into account the accumulation of the entire amount of wastewater over 6 months.

The distribution of preparatory manure runoff on irrigation fields is allowed by irrigation along furrows and strips with low-directional sprinklers, mobile means (with appropriate justification) and underground (subsoil) irrigation. The rates for applying manure and manure runoff to irrigation fields should be calculated taking into account the type of crops, their removal with the harvest and natural losses during the irrigation process (20-30%). When supplying liquid manure to irrigation fields, special flow metering devices (water meters) must be used, built into the structures for the release and supply of wastewater to irrigation or into sewer pipes.

Land irrigated with manure runoff from livestock farms is allowed to be used only for forage grasses, forage-row-crop and grain-fallow crop rotations (feeding of forage crops is allowed after ensiling or heat treatment, i.e. processing into vitamin flour).

Bodies and institutions of the sanitary-epidemiological service (sanitary and epidemiological stations of autonomous republics, territories and regions) carry out sanitary supervision at the stage of selecting a land plot for the construction of livestock complexes, linking projects of livestock complexes and projects of manure and manure wastewater treatment systems to the site, and also consider manure use systems and manure runoff for fertilizing and irrigating agricultural lands.

When considering projects of irrigation fields for the use of manure and manure runoff from livestock complexes, it is necessary to pay attention to the compliance of the allocated land areas with the amount of manure runoff generated. Calculation of areas is carried out in accordance with permissible load standards and additional allocation of areas for passages, embankments, canals, etc. (15-25% of the total territory). Manure treatment facilities are located below water intake structures and production areas.

When carrying out state sanitary supervision during the construction of systems for the collection, removal, storage, disinfection and use of manure and manure waste, it is necessary to pay attention to the compliance of objects and structures with the approved project; construction deadlines, bearing in mind that the commissioning of treatment facilities must precede the completion of construction of the livestock complex.

Current sanitary supervision is carried out in the following areas: a) conditions for the formation of manure and manure waste on livestock farms, their quantitative and qualitative characteristics over time: upon completion of construction of facilities and during operation;

b) assessment of the efficiency of manure and manure waste treatment systems based on sanitary-chemical, bacteriological, helminthological and other indicators; c) the influence of manure and manure runoff on the condition of the soil, open water bodies, groundwater and atmospheric air; d) study of the sanitary living conditions of the population in the areas where the livestock complex is located. Constant monitoring of the operation of facilities for the treatment and disinfection of wastewater from livestock complexes, their impact on surface water bodies and groundwater, atmospheric air, soil and plants is provided by a departmental production laboratory.

Sanitary protection of water bodies from pollution by pesticides. Pesticides enter reservoirs with rain and melt water (surface runoff); during air and ground processing of agricultural land and forests; when directly treating water bodies with pesticides; with drainage and collector waters when growing cotton and rice; with wastewater from pesticide production plants and generated in agriculture as a result of the use of pesticides (see also Chapter 17).

Samples for water testing are taken quarterly (more often if necessary). During the period of pesticide use in agriculture, monitoring of water quality and the sanitary regime of reservoirs in the immediate vicinity of the fields is established (water samples are taken before and after treatment, at the end of work with pesticides). The content of pesticides in drainage and collector waters is systematically monitored (sampling frequency is set depending on local conditions). Simultaneously with water sampling, sludge samples are examined. In water samples from artesian wells, wells, captages in the nearest and more distant areas, where, according to local conditions, deterioration in water quality can be expected, drinking water is analyzed according to general indicators and specific determinations for the presence of pesticides used in the treatment process. Drainage and collector waters containing pesticides in concentrations above the maximum permissible limits are prohibited from being reused for irrigation.

When choosing the form of the drug from the standpoint of sanitary protection of water bodies, preference should be given to granular forms, since in this case the danger of the drug being carried into the water body is significantly reduced and a gradual release of the pesticide into the external environment is ensured when the granules are destroyed. The least favorable in this regard are dusts.

Treatment of agricultural areas with pesticides may be permitted if it is possible to maintain a sanitary protective gap of at least 300 m between land and water bodies.

Cleanliness of water bodies: pollution, self-purification, protection

Introduction

At all times, water was considered the invaluable moisture of life. And although those years are far behind us when we had to take it from rivers, ponds, lakes and carry it several kilometers to the house on rocker arms, trying not to spill a drop, people still treat water with care, caring about the cleanliness of natural reservoirs, about the good condition of wells, pumps, water supply systems. In connection with the constantly growing needs of industry and agriculture for fresh water, the problem of preserving existing water resources arises with all severity. After all, water suitable for human needs, as statistics show, there are not so many on the globe. It is known that more than 70% of the Earth's surface is covered with water. About 95% of it comes from the seas and oceans, 4% from the ice of the Arctic and Antarctic, and only 1% is fresh water from rivers and lakes. Significant sources of water are found underground, sometimes at great depths.

About 4.5 thousand km3 - a sea of ​​water - is the annual flow of our rivers. However, water resources are distributed unevenly across the country. Consumers, using water, pollute it, this gradually leads to the depletion of clean fresh water and the need to take measures to protect it. Such water use, without affecting the quantity of water, significantly affects its quality. The party and government pay great attention to issues of nature conservation and the rational use of its resources, including water. This is evidenced by such laws on environmental protection adopted in the USSR as “Fundamentals of water legislation of the USSR and Union Republics”, the resolution of the Central Committee of the CPSU and the Council of Ministers of the USSR “On additional measures to ensure the rational use and conservation of the natural resources of the Lake Baikal basin” (1971) .

In recent years, many powerful treatment facilities have been put into operation, the efficiency of treating wastewater discharged into water bodies has been increased, and the responsibility of economic authorities has increased. A difficult task, requiring billions of dollars in expenditure, was the protection of the river. Volga and Ural, lake. Baikal and our other reservoirs from industrial pollution. Water in our country is a national property, and care for it should be popular and constant. Not only the development of industrial and agricultural production, but also the life and health of Soviet people today and in the future depends on the rational use of water resources, on a careful, economical attitude towards them. Our country - world leader in scale and the pace of water management construction, the creator of a comprehensive sanitary-epidemiological service and public health care, its preventive direction. The most important property of water is its continuous circulation. It looks like there are two circles - horizontal and vertical. Water exchange in the horizontal direction is carried out by sea currents and rivers. The mighty ocean current alone, the Gulf Stream, transports 25 times more water from south to north over thousands of kilometers per year than all land rivers.

The vertical circulation is made up of evaporation from the surface of oceans, seas, lakes and atmospheric precipitation falling on both the water surface and land. The energy of the sun's rays causes the oceans to release 355 thousand km3 of water to the atmosphere per year. Only 1/10 of this amount falls over land as rain or snow, the rest returns back to the oceans. But the entire life of the continents is largely determined by these precipitations. Huge volumes of water allow living organisms to pass through, using it for life processes. Not a single life process in the human or animal body can take place without water, and not a single cell is able to do without an aqueous environment. Almost all functions of the body occur with the participation of water. Thus, evaporating from the surface of the skin and respiratory organs, water takes part in thermoregulation processes.

But I need water Of course, not only for drinking: it also helps to keep a person’s home and environment clean. Water is the best hygienic product for facial skin care. When washing, the cells of the stratum corneum of the skin swell and are rejected along with the dust, dirt, grease, and sweat residues that have settled on them. Patting and stroking your face while washing enhances the cleansing effect of water. At the same time, blood circulation increases, metabolism increases, nutrition and skin tone improve. Water in the human body is both a medium and a direct participant in physiological and biochemical reactions. With water, various substances formed as a result of metabolism are released from the body. Imagine that such polluted water directly from a river or lake is used for drinking. Pathogens entering the human intestine find favorable conditions for reproduction there, resulting in acute intestinal disease. Since a large number of people usually use one source of water supply, the route of spread of the disease through water is the most widespread, and therefore the most dangerous.

Self-purification of reservoirs

The most interesting natural phenomena are the ability of reservoirs to self-purify and the establishment of so-called biological equilibrium in them. It is ensured by the combined activity of the organisms inhabiting them: bacteria, algae and higher aquatic plants, various invertebrate animals. Therefore, one of the most important environmental tasks is to maintain this ability.

Every body of water is complex living system where plants and specific organisms live, including microorganisms that constantly multiply and die. If bacteria or chemical impurities enter a reservoir, then in pristine nature the process of self-purification proceeds quickly and the water restores its original purity. The factors of self-purification of reservoirs are numerous and diverse. Conventionally, they can be divided into three groups: physical, chemical and biological. An important physical factor in the self-purification of reservoirs is ultraviolet radiation from the sun. Under the influence of this radiation, water is disinfected. The disinfection effect is based on the direct destructive effect of ultraviolet rays on protein colloids and enzymes of the protoplasm of microbial cells. Ultraviolet radiation can affect not only ordinary bacteria, but also spore-bearing organisms and viruses.

Among the chemical factors of self-purification of reservoirs, oxidation of organic and inorganic substances should be noted. The self-purification of a reservoir is often assessed in relation to easily oxidized organic matter (determined by biochemical oxygen demand - BOD) or by the total content of organic substances (determined by chemical oxygen demand - COD.
The process of self-purification of the reservoir involves algae, mold and yeast. Bivalves- permanent inhabitants of reservoirs - are orderlies rec. By passing water through themselves, they filter out suspended particles. The smallest animals and plants, as well as organic debris, enter the digestive system; inedible substances settle on the mucus layer covering the surface of the bivalves’ mantle. As the mucus gets dirty, it moves to the end of the sink and is thrown into the water. Its lumps represent a complex concentrate for feeding microorganisms. They complete the chain of biological water purification.

Sources of pollution

The main cause of pollution of water sources is the discharge of untreated or insufficiently treated wastewater into water bodies by industrial enterprises, as well as municipal and agricultural enterprises. Pollution of water sources also contributes to unsustainable agricultural practices: residues of fertilizers and pesticides washed out of the soil end up in water bodies and pollute them. Although water losses in many industrial processes (due to evaporation and leakage) are small, in total industrial enterprises consume enormous amounts of water, and some of it is lost irretrievably or does not undergo any treatment.

WITH the power of rivers to cleanse themselves thanks to the biological processes occurring in them, it made it possible to cope with waste. The fact that most cities, and with them large enterprises, were built on watersheds and in the headwaters of rivers was previously perceived only as a historical landmark. Cities are growing like people, albeit more slowly. And a person does not always have time to assess in his lifetime how the city’s needs for water have changed. But there are changes, and sometimes quite significant ones. After all, reservoirs in current conditions are a place not only for water intake (withdrawal of water for industrial, drinking and other needs), but also for receiving wastewater. Modern agricultural production, like industry, can be a source of pollution. Mineral salts washed out from irrigated lands pollute water bodies; pesticides, phosphorus and nitrogen fertilizers are often used uncontrollably. Excess chemicals poison the flora and fauna of water bodies. In addition, chemicals can accumulate in products, thereby posing a significant threat to human health.

Sources of pollution of water bodies in rural areas also include large livestock complexes. The source of pollution of water bodies with harmful substances is ship wastewater. In recent years, reservoirs and rivers have received many thousands of units of the so-called small fleet: boats, various boats with outboard motors. With a roar, with a white wake of breakers, with circular turns, throwing out exhaust gases, they rush back and forth across the blue waters. It is known that 1 g of petroleum products spoils 100 liters of water. Wherein the content of petroleum products exceeds the permissible level. A wave raised by a fast-moving boat reaches the shore, destroys it, and the shore is intensively eroded. There is also a very significant source of water pollution that is practically uncontrollable. These are storm and snow runoff from forests, agricultural lands, etc. In terms of pollution, such water flowing from vast territories is often comparable to urban sewer water.

Sanitary protection of the reservoir

In accordance with the “Fundamentals of Water Legislation of the USSR and Union Republics,” which were adopted in December 1970 by the Supreme Soviet of the USSR, schemes for the integrated use and protection of water are being developed. All measures should ensure the most efficient use of water for the national economy (taking into account the priority satisfaction of the water needs of the population) by regulating water flow, taking measures to use water economically and to stop the discharge of untreated wastewater based on improving production technology -stva and water supply schemes (use of waterless technological processes of air cooling, recycling water supply and other technical methods). The “Fundamentals of Water Legislation of the USSR and Union Republics” states that all waters and water bodies are subject to protection from pollution, clogging and depletion that affect water quality in such a way that they can cause harm to public health, lead to a decrease in fish stocks, worsen water supply conditions and cause other adverse consequences as a result of changes in the physical, chemical, biological properties of water, a decrease in the ability for natural purification, and disruption of hydrological and hydrogeological regimes. The definition of the concept of “water pollution” in legislation requires all water users to comply with the necessary requirements, which are set out in the “Rules for the protection of surface waters from pollution by wastewater” (1974).

The most important component of modern Soviet water and sanitary legislation are hygienic standards - maximum permissible concentrations (MPC) of harmful substances in the water of reservoirs. Compliance with these MPCs creates safety for public health and favorable conditions for sanitary and domestic water use. They are a criterion for the effectiveness of various measures to protect water bodies from pollution and stimulate progress in the field of industrial technology for the most complete compliance with regulatory requirements corresponding to the favorable sanitary condition of water bodies. The role of hygienic maximum permissible concentrations in the examination of projects and in determining the conditions for the discharge of wastewater into a reservoir to predict its sanitary condition is enormous. Hygienic standards are an important part of " Rules for the protection of surface waters from pollution by wastewater." Hygienic maximum permissible concentrations ensure safe and normal conditions for water use by the population (drinking, cultural and domestic). Maximum permissible concentrations of harmful substances in the water of reservoirs as hygienic standards make it possible to distinguish pollution levels that directly or indirectly affect the sanitary conditions of water use and public health from pollution levels that affect not so much the interests of health care as other economic interests of the population.

Developed in the late 40s by prof. S. N. Cherkinsky’s methodological scheme for the hygienic study of the possible influence of industrial wastewater entering reservoirs and the harmful substances contained in them has become generally accepted. Such research must be multifaceted and comprehensive. It should characterize the regulated substances according to the main three indicators of harmfulness - the effect on the general sanitary regime of water bodies, on public health and the organoleptic properties of water, when taste, color, and smell are determined using the senses. The hygienic criterion of harmfulness is based on the degree of restriction in water use caused by pollution that creates a health hazard or deteriorates the sanitary living conditions of the population.

According to the “Rules for the protection of surface waters from wastewater pollution,” reservoirs and watercourses (water bodies) are considered polluted if the composition and properties of the water in them have changed under the direct or indirect influence of industrial activities and domestic use by the population and have become partially or completely unsuitable for one of the types of water use. The criterion for water contamination is the deterioration of its quality due to changes in its organoleptic properties and the appearance of harmful substances for humans, animals, birds, and fish. An increase in water temperature changes the conditions for the normal functioning of aquatic organisms. The suitability of the composition and properties of surface waters used for domestic and drinking water supply and cultural and everyday needs of the population, for fishing and economic purposes, is determined by their compliance with the requirements and standards set out in the above-mentioned document.

There are two categories of water use. First category-use of a water body as a source of centralized or non-centralized drinking water supply and for water supply to food industry enterprises; the second category is the use of a water body for swimming, sports and recreation of the population, the use of water bodies within populated areas. The water use points of the first and second categories closest to the place of wastewater discharge are determined by the bodies and institutions of the sanitary and epidemiological service with mandatory consideration of official data and prospects for using the water body for drinking water supply and cultural and everyday needs of the population.

Composition and properties of water and water bodies must comply with the standards in the site (a certain section of the reservoir) located on watercourses 1 km upstream of the nearest point of water use (water intake for domestic and drinking water supply, places for swimming, organized recreation, territory of a populated area, etc.) . p.), and on stagnant reservoirs and reservoirs - 1 km in both directions from the point of water use. When discharging wastewater within a city (or any populated area), the first point of water use is the given city (or populated area). In these cases, the established requirements for the composition and properties of water in a reservoir or stream must apply to the wastewater itself. The composition and properties of a water body at points of household, drinking and cultural and domestic water use or according to one of the indicators should not exceed the maximum permissible concentration of harmful substances in water bodies of household, drinking and cultural and domestic water use. Currently, maximum permissible concentrations are established for bolt 800 substances.

One of the essential structures for the protection of water bodies is sewerage, which is a complex of sanitary and engineering structures that ensure the collection and rapid removal of contaminated wastewater outside populated areas and industrial enterprises, their purification, disinfection and neutralization. Methods for treating domestic wastewater are divided into mechanical and biological. During mechanical cleaning wastewater separation occurs between the liquid and solid phases of wastewater. For this purpose, the following structures are used: grates, sand traps, settling tanks (horizontal and vertical), septic tanks, two-tier settling tanks. The liquid part of wastewater is subjected to biological treatment, which can be natural or artificial. Natural biological treatment of wastewater is carried out in filtration fields, irrigation fields, biological ponds, etc. For artificial biological treatment, special structures are used - biological filters, aeration tanks. Sludge treatment. produced on sludge beds or in digesters.

The regulation stipulates that state control over the use and protection of water must ensure compliance by all ministries, departments, enterprises, institutions, organizations and citizens with the established procedure for the use of water, fulfillment of obligations to protect it from pollution, clogging and depletion. It is necessary to comply with the rules for accounting for water use established by the “Fundamentals of Water Legislation of the USSR and Union Republics.” The epidemiological service carries out work on the sanitary protection of water bodies in accordance with the “Regulations on state sanitary supervision in the USSR” of 1973. The bodies of the sanitary and epidemiological service of the USSR Ministry of Health are responsible for the protection of water bodies - an aspect affecting the interests of health care and sanitary living conditions population. The healthcare system has 4260 sanitary and epidemiological stations. By the Decree of the Central Committee of the CPSU and the Council of Ministers of the USSR “On measures to further improve healthcare and develop medical science in the country” (1968), a wide network of sanitary laboratories was created at enterprises to study the composition of wastewater and the quality of water in reservoirs. Each laboratory conducts tens of thousands of analyzes of water and water bodies per year.

The sanitary laboratory and its branches at wastewater treatment plants operate according to a unified plan approved by the management of the enterprise after detailed coordination with the sanitary and epidemiological service. The objects of sanitary observations are reservoirs that are used for household, drinking and cultural and everyday needs of the population. The observation sites are confined to points of sanitary and domestic water use. Sanitary condition of reservoirs, having fishery significance, and the implementation of measures for their protection are controlled by the fisheries protection authorities of the Ministry of Fisheries of the USSR. Control over the use and protection of groundwater, as well as the study of their condition, is carried out by the USSR Ministry of Geology. When conducting sanitary observations of the condition of water bodies, it is necessary to collect information about the main sources of pollution. At the same time, issues of sanitary improvement of the settlement, conditions for the disposal of its wastewater, data on other sources of pollution, in particular on industrial and other facilities discharging wastewater, the quality and composition of discharged wastewater, the nature of treatment and disinfection, etc. d.

Materials on the water quality of reservoirs are linked with data on their hydrogeological regime, which makes it possible to evaluate the results of sanitary laboratory studies and use them in predicting the water quality of reservoirs. In conditions of polluted water bodies, it is necessary to find more effective means of monitoring water quality. An automated water quality monitoring system for the entire Moscow water basin has been created - ANKOS - V (automatic monitoring of environmental control - water). It provides automatic measurement and transmission of data to the information processing center from an electronic computer, and from there through the control center directly to consumers. ANKOS-B will allow not only to quickly record the level of water pollution, but also to regulate water quality when connected to an automated wastewater control system, and to quickly evaluate the effectiveness of measures to protect the aquatic environment. ANKOS-B will serve as a prototype for similar systems throughout the country.

Posts along the river banks

Each federal republic has nature conservation societies, numbering about 35 million members, which assist government agencies in implementing and monitoring the use of legislation, as well as in planning nature conservation measures.
Concern for the purity of water opens up a wide field of activity for the public, members of the Society for the Conservation of Nature.
Caring for nature is rewarded by its generosity, a growing economy, and the joy of people. An example of this is the comprehensive transformation of the Desna basin, organically connected with the program for the renewal of the Non-Black Earth Region, with the five-year and long-term plans for the region.
Over the past decade, “green” and “blue” patrols, school forestry units, and soil erosion control units have become widespread. In the Russian Federation alone, there are 7 thousand school forestries, about 100 thousand “green” patrols and 17 thousand “blue” patrols.

Bibliography:

Yu. V. Novikov. "Keep water bodies clean"

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Freshwater bodies perform several functions. On the one hand, rivers and lakes form an important part of the water cycle in nature.

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On the other hand, it is an important environment for life on the planet with its own unique complex of living organisms.

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Large rivers and lakes are a kind of heat trap, since water has a high heat capacity. On cold days, the temperature near bodies of water is higher, as the water releases stored heat, and on hot days, the air above lakes and rivers is cooler due to the fact that the water accumulates excess heat. In the spring, lakes and rivers become resting places for migratory waterfowl, which migrate further north, into the tundra, to nesting sites.

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Rivers and lakes serve as the only accessible source of fresh water on our planet. Currently, many rivers are blocked by hydroelectric dams, so the water in the rivers plays the role of a source of energy.

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Picturesque banks of rivers and lakes allow people to enjoy the beauty of nature. That is why one of the most important meanings of land-based bodies of water is a source of beauty.

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In the Arkhangelsk region, in addition to the listed functions, rivers play the role of transport routes along which various goods are transported.

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Previously, timber rafting was carried out along the Onega, Northern Dvina and other rivers. With this method, a large number of logs were independently floated downstream during the spring flood. Thus, wood was delivered free of charge from logging areas to large sawmills in Arkhangelsk. This method of floating trees caused irreparable damage to nature. The bottom of the rivers where moth rafting was carried out was heavily clogged with rotting logs. Such rivers became unnavigable in the summer. As a result of wood rotting, there was a low oxygen content in the water.

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Despite its high economic efficiency, this method of transporting wood caused great harm to the environment. Therefore, it has now been abandoned. Nowadays, wood is transported along rivers in the form of large rafts. In this case, there is no loss of logs, and therefore, rivers and the sea are not polluted.

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Northern rivers are famous for their abundance of diverse fish. They are inhabited by whitefish, char, omul, and herring. In the spring, the valuable commercial fish northern salmon, or salmon, comes to the rivers flowing into the White and Barents Seas to spawn. Currently, the number of this species has greatly decreased due to poaching. To preserve salmon, the state regulates fishing standards for special fishing teams. But sometimes residents catch salmon with nets on their own without permission from fisheries conservation organizations; in this regard, the problem of poaching in the northern rivers is especially acute.

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SALMON is an anadromous fish of the salmon family. Length up to 150 cm, weighs up to 39 kg. After feeding in the sea, it migrates to rivers to breed. There are two known races of salmon in the White Sea: autumn and summer. The Northern Dvina salmon run begins in the spring and continues until freeze-up.

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The main negative impact of humans on the condition of rivers and lakes is their pollution by chemical waste. The Northern Dvina is the most polluted. The largest pulp and paper mills in Europe are located on this river. One of them is located near Kotlas, in the city of Koryazhma, and the other two are in Novodvinsk and Arkhangelsk.

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The total pollution of the Northern Dvina is so high that in summer it is not recommended to swim in the river within the city of Arkhangelsk. The problem of water pollution in Arkhangelsk is particularly acute, since in this city the river is the only source of drinking water. To control the quality of fresh water, the state has developed a Water Code. The Law of the Russian Federation “On the Protection of the Natural Environment” has a separate article on the protection of fresh waters. In Russia, maximum permissible concentrations and maximum permissible standards for discharges of harmful substances from industrial enterprises have been developed. The General Directorate of Natural Resources and Environmental Protection is responsible for the implementation of these laws and for monitoring the quality of wastewater.

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Another source of pollution of rivers and lakes is domestic wastewater. Most of the large cities in the Arkhangelsk region are located on the banks of large rivers. Therefore, large amounts of insufficiently treated wastewater can end up in rivers and then into the sea. To maintain high water quality in the rivers of the Arkhangelsk region and preserve the diverse flora and fauna, industrial enterprises must comply with pollutant emission standards, and the population must comply with environmental laws and take care of the wealth that nature has awarded.

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Literature Ecology of the Arkhangelsk region: Textbook for students in grades 9-11 of secondary schools / Ed. Ed. Batalova A. E., Morozova L. V. - M.: Publishing house - Moscow State University, 2004. Geography of the Arkhangelsk region (physical geography) 8th grade. Textbook for students. / Edited by Byzova N.M. - Arkhangelsk, publishing house of the Pomeranian International Pedagogical University named after M.V. Lomonosov, 1995. Regional component of general education. Biology. - Department of Education and Science of the Administration of the Arkhangelsk Region, 2006. PSU, 2006. JSC IPPC RO, 2006

Our reservoirs and their protection (E. S. Liperovskaya)

Water protection and school

The importance of reservoirs in the national economy. In school curricula, little attention is paid to such an important object of the national economy as reservoirs.

Meanwhile, the water resources of our country are enormous. In the Soviet Union there are more than 250 thousand lakes with an area of ​​over 20 million hectares and 200 thousand rivers. The total length of our medium-sized rivers is 3 million kilometers. The annual flow of rivers in the USSR reaches 4000 billion cubic meters. Hundreds of thousands of kilometers of rivers are used for water transport. Since ancient times, rivers have been the main routes of communication, trade and cultural connections between peoples, and cities arose along their banks.

The USSR ranks first in the world in terms of hydraulic energy reserves. Hydroelectric power stations with a capacity of about 300 million kilowatts can be built on large and medium-sized rivers of the USSR. Even on small rivers there is an energy reserve of 20-30 million kilowatts, which ensures the construction of collective farm power plants.

The construction of dams, locks, and hydroelectric power stations contributes to the integrated use of rivers: navigation conditions are improved, field irrigation is improved, river flow is regulated, and settlements are provided with water. The construction of large dams and hydroelectric power stations is transforming the entire region. Construction of the canal named after. Moscow allowed part of the Volga waters to turn towards Moscow and created a shipping route, turning Moscow into a major river port of three seas: the Caspian, White and Baltic. The construction of a powerful hydroelectric power station named after Lenin in the area of ​​the city of Kuibyshev and the Volgograd hydroelectric power station, generating about 10 billion kilowatts per year each, will supply energy to Moscow, Donbass, the Urals, Kuibyshev, electrify railways, ensure land irrigation and shipping.

Reservoirs are sources of water supply, fishing, hunting, and useful aquatic animals and plants.

Rivers and lakes are also places of recreation and tourism.

Participation of schoolchildren in the protection of water bodies. We must be well aware of, protect and increase our water resources.

Article 12 of the Law on Nature Protection of the RSFSR, dedicated to the protection of water bodies, poses tasks of enormous importance to every Soviet citizen.

Promoting the protection of natural waters among schoolchildren is of great importance. Already in the elementary grades, the teacher must instill in students an attentive and careful attitude towards water sources, teach them to keep wells and other water supply sources clean, not pollute the water with garbage when boating, and explain the importance of water sources for health and the national economy.

In secondary schools, the topic of water protection can be the subject of special excursions, during which the teacher must show the relationship of reservoirs with the surrounding landscape and the dependence of aquatic animals and plants on the state of pollution of reservoirs.

In high school, students can not only get acquainted with the life of reservoirs, but also actively contribute to their protection. Regular observations of the regime of local reservoirs by schoolchildren can bring considerable benefit.

The Main Directorate of the Hydrometeorological Service under the Council of Ministers of the USSR is responsible for recording all water resources, including rivers. Monitoring of rivers and their regime is carried out at special hydrometeorological posts and hydrometeorological stations. The number of such stations was 5510 in 1957 and has now increased greatly. At these stations, water levels, flow rates, temperature, ice phenomena, sediment, water chemistry and other data are recorded daily. All this information is summarized and published in a periodical publication of the Hydrometeorological Publishing House, called the “Hydrological Yearbook”. The data obtained is used for planning the national economy. Along with this, the study of rivers by local organizations, including school organizations, can be very important, and all observations obtained in this way should be reported to hydrometeorological service organizations - preferably to the nearest water-measuring station.

To successfully familiarize students with the life of our reservoirs and participate in their protection, the teacher must himself acquire basic information about this area.

Nature and life of reservoirs

River flow. Movement of water in the river. The movement of water in rivers has a number of features and is characterized by complex phenomena specific only to rivers.

River runoff is formed from atmospheric precipitation flowing into the river along the surface (surface runoff) and seeping through the soil (underground runoff). The unevenness of precipitation and snow melting both within one year and in different years causes continuous changes in flow rates and water levels in rivers. In accordance with this, rivers experience periods of prolonged low levels, the so-called low-water period, when the river is fed mainly by groundwater, and seasonal long-term rises in levels (usually with the release of water onto the floodplain), caused by snowmelt, called floods. In contrast to floods, irregular, relatively short-term significant rises in water levels can also occur in the river - floods resulting from heavy downpours or heavy rains. Floods can occur at any time of the year, depending on local geographic and climatic conditions. They reach particular strength when destroying forests in the river basin, regulating spring snowmelt and weakening erosion from the soil surface. That is why the protection and proper exploitation of forests is one of the most important tasks in regulating river flow.

The main force that determines the forward movement of water in rivers is the force of gravity due to the slope of the river from the source to the mouth. In addition to gravity, the mass of water in the river is affected by inertial forces called Coriolis forces, which arise as a result of the rotation of the Earth, since points on the surface of the globe located closer to the poles move in a circle more slowly than those lying near the equator. The mass of water in a stream flowing in the northern hemisphere from north to south will move from lower to higher speeds, that is, it will receive acceleration. Since the Earth's rotation occurs from west to east, acceleration will be directed to the east, and inertial forces in the opposite direction - to the west and will press the flow towards the western (right) bank. When the flow moves from south to north, it will receive negative acceleration directed against the direction of the Earth's rotation - from east to west. In this case, inertial forces will press the river to the eastern, i.e., also right, bank. Also, the stream flowing along the parallel will be pressed against the right bank. Thus, it turns out that Coriolis forces in the northern hemisphere always push the flow to the right bank, regardless of the direction of the river flow, and in the southern hemisphere - vice versa. Coriolis acceleration, acting on a moving mass of water, causes the appearance of a transverse slope of the water surface of the flow.

The centrifugal force acting during the river flow at turns, similar to the Coriolis force, also creates a transverse slope in the river. As a result, water begins to move in the plane of the living section of the river. In this case, near the concave shore, water particles move from top to bottom, then along the bottom to the convex shore and further, near the surface, from the convex shore to the concave one. These internal currents are called transverse circulations. The movement of water in the river in the longitudinal direction combines with transverse circulations, and as a result, the paths of movement of individual water particles take the form of spirals elongated along the riverbed (Fig. 1).

River bed formation. Despite the fact that the transverse velocities of water movement are many times lower than the longitudinal velocity of the flow, they have a serious impact on the internal structure of the flow and on the deformation of river channels. Since soils are usually heterogeneous, in the place where they are most susceptible to erosion, the shore will begin to collapse. The river will take on a characteristic meandering shape. The bends of river channels, formed in the process of erosion and deposition by the flow of soil particles, are called meanders (meo in Latin - flow, move).

In the process of their gradual development, the branches of the meander can become so close to each other at the base that at high water levels (during floods and floods), the remaining isthmus will break through (Fig. 2), the channel will straighten in this area and the flow will be directed along a shorter path. The flow velocities in the bend that remains to the side will drop sharply, and sediment deposition will begin at the beginning and end of it. These sediments can eventually completely separate the bend from the main channel. An isolated section of the old channel is formed - an oxbow lake. A flow moving along a straightened section with a greater slope will increase its speed, the process of meandering the channel will continue, and the formation of new bends will begin.

As a result of intense water circulation at bends, the concave banks are washed away and deep-water sections of the channel-reaches are formed near them, and near the convex banks the flow slows down and shallow sections - shoals - are created. Gradually growing downstream, they can lead to the formation of shoals and spits near the convex bank. Since reaches are formed alternately at the right and left banks, the transverse circulation of one direction is transformed into circulation of the opposite direction. This leads to the fact that the transverse circulations at the point of transition from one reach to another are weakened and break up into two (or more) independent equally directed circulations. Sediment begins to settle across the entire width of the river and forms shallow areas - riffles that cross the river from bank to bank and completely or partially connect two adjacent shallows. The river seems to slide down the river valley and gradually recycles all the soils that make up the floodplain.

Floodplains can be of different widths. On the Oka River near Kashira the width of the floodplain is 1 km, near Ryazan - 15 km, and on the Volga between Volgograd and Astrakhan there is the Volga-Akhtuba floodplain, the width of which ranges from 30 to 60 km.

Flood meadows are very fertile, as they are fertilized every year with river silt. In small floodplains that mostly dry up in summer, a lot of aquatic animals breed, which are washed into the river during floods.

Lake formation. A lake is a natural body of water, which is a large mass of water inside a closed pit, constantly at rest or slowly flowing. The formation of lake depressions (otherwise called beds or pits) in the Moscow region depends on the following main reasons:

1) damming of the river with accumulated sediments; 2) the formation of failures in place of dissolving calcareous rocks; 3) excavation of soil from quarries; 4) glacier activity.

Most lakes in the Moscow region are of glacial origin. As the glacier moved, it created a channel, rolling stones, sometimes of considerable size. Glacial lakes can be recognized by the presence of ridges of huge smooth boulders along the shores and at the bottom of the lake.

Over time, the lake changes, causing significant impacts on its shores. As a result of the processes of erosion and sedimentation, the following series of zones are formed in the lake in the direction from the shore to depth (Fig. 3):

1) surf zone (already) - at the water’s edge;

2) coastal shallows (zhz);

3) underwater slope (sg);

4) deep-water zone - in the middle of the lake (gd).

Lake inhabitants. The bottom and water column of the lake are inhabited by animals and plants; Among them, two main groups are distinguished depending on their habitat: bottom - benthos and organisms of the water column - plankton. The benthos (animals and plants) spend their entire lives at the bottom of the lake. Planktonic organisms float or seem to float in water without sinking to the bottom (A. N. Lipin, 1950).

Plants in the reservoir are distributed in the so-called littoral zone, which is located along the coastal shallows and partially extends onto the underwater slope. The littoral zone is limited by the range of penetration of sunlight under water. As can be seen in Figure 4, plants grow closer to the shore, rooting at the bottom, whose hard leaves rise above the water: reeds, reeds, lake horsetail, cattails.

Further, in the direction from the shore to the middle of the reservoir, there are plants with floating leaves: water lilies, egg capsules, duckweed, and even further submerged plants - pondweed, villain, hornwort, which are completely under water and expose only flowers to the air.

The smallest lower plants, such as blue-green algae, green algae and diatoms, form plant plankton, which during periods of their strong reproduction causes the so-called bloom of the reservoir. During flowering, all the water appears green.

Chemistry of water. Fresh water contains small amounts of salts - from 0.01 to 0.2 g per liter, in contrast to sea water, where the salt concentration reaches 35 g per liter.

Fresh waters are dominated by calcium salts, which form the skeletons of fish and the shells of some invertebrates. Iron salts are also present in water. Iron deposits can be seen as rusty spots along the banks of rivers or lakes where springs come to the surface. If there is a high iron content in drinking water, an unpleasant rusty taste occurs and a brown precipitate forms.

For aquatic organisms, gases dissolved in water - oxygen and carbon dioxide - are of great importance. Oxygen comes from the air and is released by aquatic plants; it is consumed during the respiration processes of organisms. Carbon dioxide is produced by respiration and fermentation and is consumed by plants to assimilate carbon. As the temperature rises, the amount of gases dissolved in water decreases. By boiling water, you can free it from all dissolved gases, including oxygen, and therefore fish dropped into boiled cooled water instantly dies from suffocation.

Reservoirs are sources of water for drinking and technical water supply systems. At the point where water is collected for the water pipeline, a security zone is established, within which the release of sewage, swimming, livestock watering, and any pollution of the banks is prohibited. The water intake site should be located along the river above the city, away from large factories, bathhouses, sewers, and also, if possible, away from tributaries that can introduce pollution from the upper reaches. The degree of purity is controlled by water tests. At the site where water is taken from the reservoir, pumps are installed to pump water. Water is taken from a depth of at least 2.5 m, passes through large gratings to retain plant residues and large suspended matter, and then flows through pipes for purification. Aluminum sulfate is usually added to precipitate turbidity. After partial separation from turbidity in settling tanks, the water enters the filters. Slowly passing through the sand layer, it is freed from suspended particles and algae. Purified water is disinfected by chlorination and supplied to a clean water reservoir, and from there it is pumped into the water supply network.

Fishes of our waters. Numerous lakes and rivers of the USSR are rich in valuable species of commercial fish. In large rivers there are, for example, sturgeon, stellate sturgeon, beluga, sterlet, pike perch, carp, and bream. However, large fish can only be caught with special gear, and amateur fishermen, including schoolchildren, usually catch smaller fish: roach, bleak, rudd, dace, asp, perch, pike, ruffe, crucian carp, burbot, tench.

In order to protect fish stocks in water bodies and catch fish correctly, you need to know how fish live. Unfortunately, there are still frequent cases of predatory fishing - poaching. Often children also fish using illegal methods. Therefore, in those schools where there are many amateur fishermen among the students, the teacher must either explain to them the rules of fishing himself, or invite a knowledgeable fisherman to do this.

Schoolchildren need to be educated in the spirit of fighting poaching. Catching juveniles of valuable fish species causes great damage to fisheries; Likewise, predatory fishing by poachers during spawning undermines the fishery. Therefore, the law prohibits fishing with a small-mesh net, fishing with a spear, and fishing for large fish during spawning periods.

A teacher in the Moscow region should have an idea of ​​the main types of local fish (Fig. 5, 6, 7); it can be compiled from the literature (Cherfas B.I., 1956, Eleonsky A.N., 1946).

Fish are bottom-dwelling (for example, bream, crucian carp, tench, burbot) and pelagic, that is, living in the water column (pike perch, pike, roach, dace). There are also peaceful and predatory fish. Predatory fish are those that feed on other fish, while peaceful fish eat algae and invertebrate animals such as mollusks, worms, and insect larvae.

Bream It has a strongly laterally compressed body, its head and mouth are small, and there is a characteristic narrow keel in front of the dorsal fin. It is found both in lakes and rivers, lives in reservoirs near the bottom, and sometimes reaches a length of 45 cm.

crucian carp usually lives near the bottom in low-flow ponds. This fish is sluggish, inactive, but extremely hardy. Crucian carp are easily distinguished by the golden hue of their scales and the jagged ray of their dorsal fin.

Asp distinguished by a long lower lip, which is curved like a bird's beak; There is a notch in the upper lip where this beak fits. The fins are gray or slightly reddish. The fish is strong and lives in fast currents. It feeds on dace, gudgeon, and bleak.

Som- a voracious predator, eats not only live prey, but also carrion. Caught on pieces of meat and frogs. Usually it lies in holes under snags, only in hot weather it swims out to the middle of the pool. Slow sedentary fish. Reaches a weight of 20 kg.

Zander also a predator (Fig. 6). Its scales are grayish on its back, its sides are golden with dark stripes. The dorsal fin is in the form of a spiny fan. It is found in rivers and lakes in deep places and holes, on clean sandy or rocky soil. Spawns in mid-May. It is caught only at dawn using small live fish: bleak, gudgeon, ruff.

Pike characterized by spotted sides, while the back is black and the belly is white (Fig. 7). The fins are orange. The elongated head ends with a flattened, duck-like nose. The mouth is full of many very sharp teeth of different sizes - from the smallest to large fangs with hard enamel. The teeth are curved inwards towards the throat. Each of the teeth is movable, as if on a hinge, but does not fall out. Pike is a large predator. Pike can be found everywhere, but it prefers calm water near grass and snags, where it hides, lying in wait for prey. It is caught with live bait, even with small squints.

Rudd distinguished by red fins. The eyes are red-yellow. Lives in thickets of plants.

Tench has rounded fins and a small mouth directed upward. The body is dark, always thickly covered with mucus, the eyes are red. Lives in lakes, bays and oxbow lakes on muddy bottoms. The fish is calm and lethargic, but strong and tenacious (Fig. 5).

At the burbot very small scales are covered on the outside with a thick layer of mucus. The body is dark with light spots, the eyes are also dark, it lives in rivers at the bottom under driftwood. It feeds on fish and caviar, of which it eats a lot. Hunts at night. Caught on pieces of fish or frogs. The fish is strong.

Ruff- small fish, up to 15 cm in length. It has one dorsal fin, the front part of which is spiny and the back part is soft. There is a spine on the ventral fin. In spring it eats fish eggs. Caught with an earthworm.

Perch has two dorsal fins and small scales. The body is green-yellow with black stripes on the sides. Eats caviar and small fish.

Pike and pike perch feed on young fish. Pike, eating up to 30 kg of small fish from other fish, increases in weight by only 1 kg. Pike perch makes better use of food: it gives a gain of 1 kg in exchange for 15 kg of small items eaten. Pike perch is advantageous in that it does not stay in the coastal strip, but on the stretch of water and feeds on low-value fish species (verkhovka).

In relation to harmful, i.e. predatory, fish, measures must be taken to reduce their numbers by catching them during the spawning period. But control is also needed over peaceful fish, since overpopulation of a reservoir with them can lead to their grinding due to lack of food.

Fish ponds. Many fish ponds have been built in the USSR, but many collective farm ponds and peat quarries can also be equipped for fish farming and stocked with fish, thereby increasing the country’s fish output.

About 250 thousand quintals of fish are currently produced in ponds alone; however, this does not reach even 1% of all fish production in the USSR. And by the end of the seven-year plan, in 1965, it is planned to increase the yield of pond fish to 2.6 million centners (Gribanov L.V., Gordon L.M., 1961).

A common form of fish ponds is carp farming (Eleonsky A.N., 1946). For carp spawning, standing or low-flowing, shallow, well-warmed by the sun reservoirs located on fertile soil with aquatic vegetation are suitable. Carp spawning occurs at the end of May, when the water warms up to 18-20°. The eggs attach to aquatic plants, and after 4-6 days tiny fry emerge from them and soon begin to feed on small aquatic animals. As they grow up, they switch to feeding on worms and larvae. The favorite food of adult carp is red bloodworm. Carp is characterized by rapid growth: in the spring it weighs 20-30 g, and by autumn it reaches 500-700 g.

Carp ponds have an average productivity of 2 quintals of fish per 1 hectare, in other words, 300 pieces weighing up to 600 g. The pond can produce such products due to the use of fish to feed living aquatic organisms. But thanks to the use of measures to intensify the economy - fertilizing ponds, fertilizing with grain, vitamins, microelements, combined compacted planting (carp along with silver carp, crucian carp and tench) - it is possible to increase the productivity of ponds by five, ten or more times. For example, on the collective farm in the village of Dedinova, Podolsk district, Moscow region, they raised about 9 centners of fish and received an income of 5.7 thousand rubles per 1 hectare of pond (Gribanov L.V., Gordon L.M., 1961). And in the fish farm "Para" of the Saraevsky district of the Ryazan region, in ponds with an area of ​​140 hectares, they even grew 19.1 centners of fish per 1 hectare of pond ("Pravda" dated July 4, 1962).

Water pollution and water purification. Enormous harm to fishing, water supply and the use of reservoirs for any other economic purposes is caused by pollution caused by waste effluents from factories and enterprises. A number of our rivers (this especially applies to small rivers) are extremely polluted. In many places, fish have ceased to be found, livestock watering places are dangerous, swimming is prohibited, and pollution threatens to reach such proportions that even after the cessation of wastewater discharge, such reservoirs will be unsuitable for national economic purposes for a long time. Pollution of water bodies is continuously increasing. The variety of wastewater is increasing. If in pre-revolutionary Russia the main pollutants were household, textile and leather waste, now, in connection with the development of industry, oil, artificial fiber, detergent, metallurgy, and paper and cellulose waste have become important. Industrial wastewater may contain toxic substances: compounds of arsenic, copper, lead and other heavy metals, as well as organic substances: formaldehyde, phenol, petroleum products, etc.

The reservoir has the ability to self-purify. Organic contaminants entering water are subject to bacterial decay. The bacteria are consumed by ciliates, worms and insect larvae, which in turn are eaten by fish, and organic pollution disappears from the reservoir. It is much more difficult to get rid of toxic substances: some substances, when absorbed by fish, make the fish meat taste unpleasant or even harmful to eat. Therefore, the sanitary inspection provides for standards for the release of toxic substances into bodies of water, above which descent is prohibited, and monitors their implementation.

Wastewater containing a lot of organic pollutants is treated biochemically. Depending on the nature of the contaminants, wastewater treatment proceeds in two ways: 1) oxidation of pollutants with air oxygen or 2) oxygen-free fermentation with the release of methane formed from the carbon of organic compounds.

Among the oxidative cleaning methods, the oldest is cleaning in irrigation fields. The disadvantage of this method is that the field area is too large. Soviet scientists have developed more intensive cleaning methods in structures that occupy a smaller area: aeration tanks or biofilters, where cleaning is carried out using activated sludge when blown with air. Activated sludge is similar to sludge from the bottom of reservoirs: the same microorganisms (ciliates, rotifers and flagellates) that can usually be found at the bottom of a reservoir develop in it, but thanks to the abundant continuous influx of organic matter with the waste liquid, which serves as food for microorganisms, and good aeration conditions , an excessively large number of bacteria and protozoa develop in the aeration tank. They intensively consume organic matter and thereby purify waste liquid. After being in the aeration tanks, the water settles to separate from the silt and, already purified in this way, is discharged into the reservoir.

Excursions to reservoirs

Purposes of excursions. Students can be introduced to bodies of water on one-day school excursions, in summer camps, during agricultural practice, and on hiking trips. To explore different types of reservoirs (lake, reservoir, pond, river), you need to conduct at least 3-4 excursions. It is also advisable to visit a fish farm, waterworks and wastewater treatment plant.

The goals of excursions with students to bodies of water are as follows:

1. Show the importance of reservoirs in the life of the region - the benefits they bring and the beauty they add to the native nature.

2. Instill in schoolchildren a love for water bodies, the habit of treating them with care and striving to increase their natural wealth.

3. In the process of observing aquatic animals and plants, develop students’ powers of observation, the ability to analyze nature and establish the patterns of life of organisms in communities.

4. Show how communities of animals and plants are closely related to the surrounding habitat conditions and landscape.

5. Involve students in the proper use of this reservoir.

Preparing for excursions. Equipment. When organizing an excursion to a reservoir, the teacher must first familiarize himself with it and find out what the surrounding landscape is like, especially vegetation and soil, the nature of the banks, and, if possible, determine the origin of the reservoir. He must find out from the local population the prevailing depths, dangerous places and holes, muddy banks, the nature of the bottom soil, and find out the possibility of traveling by boat.

From a conversation with fishermen, the teacher finds out what types of fish are found in the reservoir, what were found before, what are the reasons for their disappearance; where industrial wastewater or domestic wastewater is located along the banks.

It is advisable to collect some of the most common species from plants and animals and identify them yourself using keys or find out their names from specialists.

Before going on an excursion, the teacher conducts a conversation in which he explains its purpose - getting to know bodies of water, their life and significance for humans.

The teacher explains how each excursion participant should keep a diary. The recording must be accurate and is always done immediately, on the spot, under the fresh impression of the observed phenomenon. The initiative of students in searching for new original forms of recordings should be welcomed.

In advance, together with the students, the teacher prepares equipment for the excursion (Fig. 8, 9, 10).

To take a plan of the lake you need: tape measure, milestones. You should stock up on special sticks as milestones instead of breaking trees; you also need a homemade compass. To make a compass, you need to take a ruler, draw a straight line on it and attach a compass in the middle so that the north-south arrow of the compass coincides with it. At the ends of the line, two pins should be inserted strictly vertically. The resulting compass needs to be mounted on a tripod.

To measure depths you need a lot. To do this, the rope is marked with colored ribbons at meters and half meters, and a weight or stone is tied to the end. The lower surface of the load is rubbed with lard so that pieces of soil stick when the load falls to the bottom.

It is better to take a thermometer with divisions in tenths of a degree or at least half a degree. The end of the thermometer is tied with hemp from a rope, like a tassel. Then, when quickly raised from a depth, the thermometer retains the temperature of the water in which it was immersed for several minutes while it is counting degrees.

A Secchi disk is used to measure water transparency. A metal round plate the size of a plate is painted with white oil paint and tied horizontally in the center with a rope. When immersing a disk, the depth at which it is not visible is taken into account.

The plankton mesh is made from silk mill gas, which is distinguished by its strength and uniform size of holes (cells); The gas number corresponds to the number of cells per 10 mm of fabric. To collect daphnia, you can use gas No. 34, and for small plankton - No. 70. The mesh consists of a metal ring with a diameter of 25 cm, bent from thick copper wire, and a fabric cone. A funnel (like a kerosene) made of stainless material with a clamp or tap at the end is attached to the end of the cone. The mesh pattern is made from a square piece of fabric (Fig. 8). Before sewing both halves of the cone, you need to use the same pattern to make arc strips (a) from calico or canvas and sew them onto the gasket.

A dredge for collecting benthos consists of a metal frame to which a bag made of rare burlap and a rope are attached. The frame is made from an iron strip 2 mm thick, 30 mm wide and 1 m long, bent into a triangle and fastened at one end.

The net is made from a metal hoop with a diameter of 20-30 cm. The hoop is attached to a stick. The net bag is made of burlap or mill gas, rounded towards the end (for its pattern, see the first article).

The scraper is used to collect fouling and organisms living in plant thickets. It is a type of net, but has a flat steel strip 2-3 cm wide. To attach the bag, holes are made on one side of the steel strip. The bag is made of coarse mill gas. To collect organisms, you need to have several jars with stoppers and alcohol or formaldehyde.

Excursion to the well. You can start the series of excursions by getting acquainted with the nearest well from which drinking water is taken. A well differs from an artesian well in the shallower depth of its aquifer. In this regard, contamination from the soil can penetrate into the well, and when constructing wells, they are located away from garbage cesspools, cemeteries and sewage drains.

By examining the well, you can become familiar with the influx of groundwater. To do this, you need to measure the depth of the well using a rope with a heavy metal glass at the end, attached to it with the bottom up. When you hit the water in the well, a loud sound is made. In the morning and evening, the water levels in the well are different due to water consumption and groundwater inflow. A bottle of water is taken from the well for chemical analysis in the school office.

Excursion to the river. When going on an excursion to the river, you need to familiarize yourself with a map of the river and its basin. If this river is small, with high school students you can measure the speed of the flow and its flow.

Current speed is measured with floats. Two alignments are selected - upper and lower. The distance between the gates is taken such that the duration of the float's travel along the river core between them is at least 25 seconds. Above the upper target at a distance of 5-10 m, another launch target is selected. It is done so that the float thrown in this alignment, when approaching the upper alignment, takes on the speed of the flow jets. After setting out the alignments, the living cross-sectional areas on two alignments are measured. The measurement of live sections is carried out by measuring the depths with a rod or pole with divisions at equal intervals, usually at 1/50 or 1/20 of the width of the river, along the towline, which is pulled at each section from bank to bank. The living cross-sectional area can be calculated using the formula: W = (n 1 + n 2 + n 3 ... n n ⋅ b, where n are the measured depths, b are the intervals between measurements in meters. Wooden circles are used as floats, sawed off from a log with a diameter of 10-25 cm and having a height of 2-5 cm. For better visibility, the floats are painted with bright paint or equipped with flags. It is advisable that the float protrudes as little as possible above the surface of the water to avoid the effects of wind.

On rivers up to 20 m wide with a more or less fast current, at the launch point, 10-15 floats are sequentially thrown into the pitch area. The moments of passage of each float through the upstream and downstream alignments are noted with a stopwatch, and the duration of the float's travel T between the alignments is calculated.

The float speed Vpop is found using the formula

V pop	L	,
	T

where L is the distance between the targets, T is the time it takes for the float to pass in seconds. Of all the floats, select the two with the highest speeds and derive Vmax from them. pov - average maximum surface speed of water in the river. Then calculate the average flow speed of the entire river V av = 0.6 V max. pov and the average living section area W for two sections - upstream and downstream. River flow Q is determined by the formula

Q = V avg × W.

For example, let us point out that the flow of the Moscow River at Pavshin is on average about 50 m 3 per second.

On the river, the temperature and transparency of water are measured in deep places, near the shore, near springs and tributaries. The differences indicate the presence of current jets.

It is useful to have students talk to local fishermen. It is advisable to attend net fishing conducted by the local population and see representatives of the local ichthyofauna.

When observing small river organisms, you should pay attention to adaptations to life in fast-flowing water. Thus, mayfly larvae, which can be found under stones, have a flattened shape that protects them from being moved by the current. Mayfly larvae differ from similar stonefly larvae by three tail filaments.

The adaptations of caddisfly larvae consist of the formation of strong houses from the surrounding material (grains of sand, leaves, sticks), due to which the animal is protected from damage when rolling along the bottom. In addition, caddisfly larvae have strong hooks with which they can cling to plants or other hard substrate. There are predators among caddisfly larvae, so it is dangerous to place them in the same aquarium with fish fry.

Along the banks of rivers you can find large bivalve mollusks (toothless and pearl barley) crawling along the bottom in places with silt rich in organic matter. They partially bury themselves in the mud, exposing their respiratory siphons into the water above the mud to draw clean water to their gills.

Excursions to a lake or pond. There are several excursions available to the lake:

1) for shooting a plan; 2) for measuring depth; 3) to get acquainted with plants and animals. An excursion to the lake can be replaced by a visit to a quiet backwater of the river, which is approaching it according to its regime.

The first excursion to the lake is carried out along the shores.

If the lake or pond is small, then it is quite possible to film its plan with high school students. It is recommended that you familiarize yourself with the methodology for this case according to Lipin’s book and use the method that uses a compass. Two people work with the compass, the rest set up milestones and measure distances. Coastal places are plotted on the plan: villages, arable lands, vegetable gardens, forests, streams flowing into a reservoir. At home, students draw a plan to a certain scale. The task is given to calculate the area of ​​the lake.

The next excursion to the lake is by boat. This excursion, like the previous one, should be carried out with older schoolchildren. Having chosen a stable flat-bottomed boat, they sail across the lake in a straight line. If we measure the depth at several points along the course of the boat, we will obtain data for compiling a longitudinal profile of the lake.

During the next trip, temperature and water clarity are measured and living material is collected. To work on collecting material, five students are needed, a minimum of three students and a teacher: a rower, a helmsman, a planktonist, a collector of plants and benthic organisms, and one person for all records. Under no circumstances should the boat be overloaded with extra people.

The work is distributed as follows: the rower rows and at certain intervals, at the command of the leader, stops the boat. It is good to have an anchor that holds the boat in place during work. The helmsman gives the direction of the boat, he can also make entries in the diary and write labels. When the boat stops, one person measures the temperature (first of the air in the shade, then of the water), depth, and transparency.

The planktonist lowers the plankton net into the water while the boat is moving slowly and, holding it barely under the surface of the water for 5-7 minutes, pulls it behind the boat. After this, he takes out the mesh, concentrates the contents in the lower funnel of the mesh, washes it into a bottle and fixes it with alcohol right there on the boat, adding 1 part alcohol to 2 parts water. It can also be fixed with formalin (5 cm 3 per 100 cm 3 of water) or even with a solution of table salt (about 1 teaspoon per 100 cm 3 of water). Organisms are well preserved in formaldehyde, but you need to work with it with caution and under no circumstances give it undiluted to children, as it is very caustic; This fixative can be used when working only with those students who can be relied upon.

One of the participants on the boat trip must be busy collecting plants, as some plants cannot be obtained from the shore. When collecting plants, the teacher draws students' attention to the arrangement of plants in zones.

Plants on the boat can be collected in damp pieces of gauze, labeled with pencil on parchment paper, and placed in a herbarium folder upon return to shore.

In order to beautifully arrange small filamentous algae on paper, you must first immerse them together with the paper in water and then carefully remove them; then the individual threads will lie evenly on the sheet, after which you can dry them.

While going around on a boat, the teacher draws attention to the flowering of the reservoir. If the bloom is intense and gives the water a thick color, you can directly scoop the water into a bottle, fix it with alcohol and then examine it in the laboratory under a microscope.

A special excursion is carried out along the shore on foot to examine the littoral zone of the lake, i.e., the coastal zone of higher vegetation. Plants are collected for the herbarium, the rhizomes of aquatic plants are dug up, and green filaments are taken into jars. Plant identification can be done using the books of Yu. V. Rychin (1948) and A. N. Lipin (1950) or other plant identification books. Not only older, but also younger schoolchildren (IV grade) can participate in such an excursion, but the teacher can change the excursion program in accordance with the level of knowledge of the students.

The littoral zone with thickets of plants is the most lively and rich in organisms, since plants provide a solid substrate for the attachment of organisms, release oxygen necessary for respiration and, when they die, provide organic remains that serve as food for aquatic animals.

Among the vegetation you can find water beetles and other insects, as well as their larvae, visible with the naked eye or through a magnifying glass.

Before catching animals, the student observes their behavior underwater. He records on what plants or on what soil the specimen was found. On a quiet summer day, the underwater population is clearly visible along the banks of shallow reservoirs. Let students try, by observing a beetle, worm, or insect larva, to decide how this organism feeds, how it breathes, whether it is a predator or whether it itself becomes a victim of others. Back at school, you can look at the characteristics of each organism in more detail under a microscope.

Approximate tasks for individual groups of excursionists may be the following: 1) fishing with nets between plants; 2) scrapings of organisms attached to stems, leaves of plants and underwater rocks; 3) collection by dredging of benthic organisms living in the mud. The material obtained in this way can be easily systematized according to the habitats of animals and relate the distribution of organisms to living conditions.

To extract organisms, the dredged sludge is washed through a sieve (sieve side size 0.5 mm). The sludge should be taken from the surface layer, since this is where the most organisms are found. Usually red bloodworm larvae, worms and small mollusks live in the silt, which need to be examined through a tripod magnifying glass and under a microscope, preferably alive, and before that kept in a jar of water. If the day is hot and the laboratory is far away, they should be preserved in alcohol or other fixing liquid.

When examining the water surface, water striders and small dark shiny whirling bugs catch the eye. Examine a bug's eye under a magnifying glass: when swimming, the lower half of their eye is immersed in water, and therefore is structured differently than the upper half. Of the large beetles, the most common beetles are the water lover, the diving beetle, and their larvae. Water beetles breathe atmospheric air. They are good swimmers, as evidenced by the structure of their limbs (Fig. 11).

Water bugs - smooth bugs, comb bugs, water scorpions - are distinguished by their sucking proboscis at the mouth.

Mollusks crawl on the floating leaves of plants (a large pointed pond snail, a reel, a meadow - all these mollusks belong to gastropods) and the eggs of the mollusks are sometimes attached in the form of transparent mucous strands and rings.

Familiarization with signs of water pollution. When walking around the banks and collecting material, you need to pay attention to whether there are signs of pollution of the reservoir. The teacher, together with the students, can provide direct benefit by reporting the presence of pollution in a given location to the district sanitary inspectorate or the branch of the Society for the Conservation of Nature.

Cemeteries, villages, factories, farmyards - all these are sources of pollution. However, both high school and junior high school students should be aware that river currents sometimes carry pollutants downriver far from sources of pollution and deposit them in quiet pools.

According to the requirements of the state standard (GOST), clean water of a reservoir should not have any foreign odor, its color when observed in a layer 10 cm high should not be clearly expressed, and continuous floating films should not form on the surface of the reservoir. These GOST requirements must be taken into account. During the excursion, you can take some water with you into a bottle for testing in the laboratory.

If traces of oil are noticeable on coastal plants and rocks near the shore of a reservoir, if a foreign odor is felt, for example phenol, hydrogen sulfide, oil, etc., films of oil and debris float on the surface of the water, or even clusters of blue-green or black cakes form - this is means that the reservoir is polluted. You cannot drink water from contaminated bodies of water, you cannot swim in them, and samples must be collected carefully so as not to cause harm. A sample from clusters of blue-green algae on the surface of the water should be collected in a jar for viewing under a microscope. Taking into account the degree of contamination by chemical analysis or microscopy of samples is available for students of at least VII grade.

One of the methods for distinguishing clean water bodies from polluted ones is a microscopic analysis of the composition of coastal fouling that forms a border on underwater objects at the water's edge.

Almost clean reservoirs are characterized by bright green fouling of algae from the green group (cladophora, edogonia, etc.) or a brownish coating of diatoms. In clean water bodies there is never the white flocculent fouling characteristic of polluted water bodies.

Blue-green fouling, consisting of algae of the blue-green group (a number of oscillatory species), characterizes not clean, but polluted water (with excess organic pollution). Similar fouling occurs in runoff with excess total salinity.

Fecal wastewater produces white-grayish flocculent fouling consisting of attached ciliates (carhesium, suvoika). Such fouling indicates poor treatment of wastewater after treatment facilities.

Almost no different from them in appearance are the whitish-fawn mucous deposits of filamentous bacteria spherotilus, which also develop in areas contaminated with organic substances. Spherotilus sometimes produces powerful, felt-like cushions.

The entry of toxic waste into a body of water in large concentrations can cause complete or partial death of living organisms. Therefore, comparing the composition of animals above and below the release of polluted water will give us an idea of ​​the degree of harmful influence of the runoff on the reservoir. The complete absence of fouling below the drain also indicates a strong (poisonous, toxic) effect of the drain.

When examining, you should pay attention to the state of higher (flowering) aquatic vegetation - pondweed, reeds, reeds, etc. Toxic wastewater can inhibit vegetation, and, conversely, the presence of biogenic salts (nitrogen, phosphorus, as is the case, for example, in wastewater phosphorite mines) causes excessive development of vegetation.

If familiarization with a lake or river can be continued in winter, then the degree of pollution can be more reliably established. The winter season is like a touchstone, since in winter the reservoir is isolated from the air by ice and the supply of oxygen in the event of severe pollution may be insufficient for a long winter. With a lack of oxygen, death occurs, and the sleeping fish floats up in the ice holes.

The hottest time for schoolchildren and youth to protect water bodies should be spring, before the flood. At this moment, the snow melts and all the pollution along the banks of reservoirs is exposed. If you do not take care of cleaning the banks in time, then the spring melt water and flood will wash away all the dirt into the reservoir, harming the fishery, and depriving the population of the opportunity to use water for a long time. The task of the schoolchildren is to, together with the teacher, under the guidance of a sanitary doctor, organize local residents for the timely removal of industrial and household waste from the banks of the reservoir.

Pollution of water bodies has a detrimental effect on fish. From a lack of oxygen in the water or a large amount of toxic substances, fish die - suffocation, without visible changes in organs and tissues. When heavily contaminated with toxic substances, fish sometimes rush about randomly, float to the surface, lie on their sides, make sharp movements in a circle or jump out of the water and, as if exhausted, sink to the bottom with their gill covers wide open.

In cases of chronic poisoning of carp, bream, and ide, the phenomenon of dropsy is observed: ruffling of the scales with a large accumulation of liquid under it. Bulging eyes are often noticeable. Changes in the internal organs are also noticeable: the liver, instead of the normal cherry color and relatively dense consistency, becomes dirty-whitish, sometimes marbled, flabby, and in some cases a shapeless mass. The buds also often have an off-white color and a flabby consistency. However, similar changes are also observed when fish become infected with rubella.

All these signs of poisoning can be observed in fish, which the guys can either catch themselves or examine from fishermen. It is also useful to tell fishermen about the listed signs of fish poisoning. Seventh grade students familiar with fish anatomy can lead these conversations themselves.

Processing excursion material

Material Definition. After the excursion, the collected material must be put in order and processed at the school.

Sixth grade students identify aquatic plants using keys. It can be determined not only by flowering specimens, but also by leaves alone (according to the book by Yu. V. Rychin, 1948).

To quickly understand the structural features of organisms, the teacher himself first determines the mass forms, writes down their main characteristics and then distributes to each of the students a specimen of the same species for examination under a magnifying glass or microscope.

As an example, let us consider the larvae of “rocker” dragonflies (with students in grades VI-VII). This is a large larva. It has three pairs of segmented legs, like all insects. The shell of the larva is hard chitinous. Let's plant a living larva in a deep saucer of water and observe its movement. It has a reactive method of movement: a stream of water is ejected from the rear end of the intestine, and the larva thereby jumps forward. Sometimes you can find empty larval skins from which an adult dragonfly has already emerged. The larva has a mask on the underside of its head that covers the lower jaw. If you carefully take the non-living larva in your left hand, you can pull the mask forward with tweezers or a stick. It serves the larva to catch prey.

If students, due to lack of time, cannot use the determinants, then it is enough to tell them the names of individual large representatives of the fauna and indicate only some of the most characteristic features. It is very useful to sketch animals, at least 2-3 copies. Sketches must be approached strictly: the drawing must be made not from a book, but from nature, resemble the object and reflect characteristic features.

Sixth grade students can examine beetles, water bugs, insect larvae, small mollusks, and leeches under a tripod magnifying glass.

Independent work with a microscope and sketching preparations can be entrusted to older schoolchildren only after they have acquired the skill in a circle.

Under a microscope, they examine: 1) algae that create a bloom in the reservoir; 2) contaminated films with accumulations of algae; 3) filamentous algae; 4) contaminated fouling removed from objects in the coastal part of lakes and rivers; 5) small organs of aquatic animals that are characteristic features of species, for example, gill filaments of mayflies; 6) daphnia (they are examined entirely and preferably alive); 7) plankton (considered live or fixed in alcohol in a drop).

Under a microscope, it can be seen that the fouling, which is green in color, consists of filamentous green algae (should be viewed under a high magnification of the microscope; the teacher prepares the specimen). Filamentous algae in each cell have a green chromatophore in the form of a plate, spiral or grain.

Colorless threads of fungi, molds or filamentous bacteria are found in the contaminated area. These threads are very thin, sometimes their diameter reaches only a few microns (1 micron is equal to 1/1000 of a millimeter). The threads show cell division (at high magnification).

Whitish fouling is also found in the contaminated area. Under a microscope, among them one can distinguish ciliates - suvoek, and others that have the shape of a bell, attached by a thread-like leg to a solid substrate.

Observations and experiments on living objects. Some animals can be placed in an aquarium to observe their movement, breathing and feeding. This can be done with beetles, dragonfly larvae, water bugs, mollusks, coil and pond snails. To determine the toxicity of river water as a result of industrial runoff flowing into it, in high schools it is quite possible to conduct a three-day experiment on the survival of aquatic organisms in this water. For testing, it is best to use daphnia, but leeches or mollusks can also be used; Mayfly larvae and bloodworms are not suitable for this, since these latter do not live well in laboratory conditions. Daphnia is caught in any small pond and kept in a jar of clean water until experiment. The water from the reservoir that they want to test for toxicity is poured into small flasks. For comparison, obviously pure river water is poured into other exactly the same flasks. 10-12 daphnia are placed in each cone. Daphnia should be replanted with a small, sparse mesh quickly and carefully, trying not to dry out or crush the crustaceans. Immediately after transplantation, check whether the crustaceans are well preserved, and exclude those flasks where they are poorly preserved from the experiment. In the remaining flasks, observe the state of the organisms for 2-3 days. If daphnia swim normally both in the experiment and in the control, it means that the water is harmless to the reservoir.

Chemical water tests. If the school has a chemical laboratory, it is possible to conduct some chemical analyzes of water, for example, determining the active reaction (acidity and alkalinity) of water. To do this, take one sample from a reservoir near the wastewater discharge and, for comparison, another from its clean area. To both samples add 2-3 drops of the indicator methyl orange, which changes color from red in an acidic environment to yellow in an alkaline environment. In case of contamination with industrial wastewater, the color of the test and control samples will be different.

The color of water is determined in cylinders 10 cm high, comparing contaminated water with distilled water.

Determination of the hardness of water from a well is carried out with soap foam. You need to make a solution of soap in alcohol. Pour water from different wells into a row of cones or bottles, and distilled water into one of them. Then you should gradually add a soap solution from a burette or pipette, shaking the liquid in the flask. In distilled water, foam is formed from a few drops of soap, and the harder the water, the more soap is needed to form foam.

Material design. The materials collected during the excursion are prepared for the school museum as follows.

Aquatic flowering plants are collected in a herbarium on sheets in a folder or on a stand under glass. You can make a poster diagram of the distribution of aquatic vegetation of a pond by zone (see Fig. 4).

The results of surveying the plan of the pond and measuring the depths are drawn in the form of a schematic drawing, as well as a model of the pond, with the coastal landscape and coastal settlements depicted.

Calculations of the area of ​​the lake, the amount of water in the lake, water flow in the river, and river flow speed can be compared with measurement data from the regional water metering station.

Collections of aquatic insects are made dry on pins in boxes; insect larvae are stored in test tubes or jars with alcohol, filled with paraffin, with labels.

Drawings of microscopically small forms and drawings made when identifying species, indicating distinctive features, are compiled in the form of an album. An album or exhibition of photographs taken by the students themselves at the pond is also compiled.

The final conversation of the teacher is devoted to the national economic significance of this reservoir, the possibility of raising fish or fishing in it, the degree of pollution of the reservoir and measures for its protection.

Literature

Gribanov L.V., Gordon L.M., Increasing intensity is the main thing in the development of pond fish farming in the USSR, Sat. "The use of ponds for intensive fish farming, M., 1961.

Dorokhov S. M., Lyaiman E. M., Kastin B. A., Solovyov T. T., Agricultural fish farming, ed. USSR Ministry of Agriculture, M., 1960.

Eleonsky A.N., Pond fish farming, Pishchepromizdat, M., 1946.

Life of fresh waters of the USSR, ed. Zhadina V.I., ed. USSR Academy of Sciences, M. - L., 1940-1956.

Kulsky A. A., Chemistry and water treatment technology, 1960.

Landyshevsky V.P., School and fish farming. State uch. ped. ed., M., 1960.

Lipin A.N., Fresh waters and their life, M., 1950.

Martyshev G.V. et al., Pond fish farming on collective and state farms, 1960.

Polyakov Yu. D., A manual on hydrochemistry for fish farmers, Pishchepromizdat, M., 1960.

Raikov B. E. and Rimsky-Korsakov M. N., Zoological excursions, 1938.

Rychin Yu. V., Flora of hygrophytes, 1948.

Skryabina A., My work with the young people, ed. "Young Guard", 1960.

Cherfas B.I., Fish farming in natural reservoirs, Pishchepromizdat, M., 1956.

Zhadin V.I., Gerd S.V., Rivers, lakes and reservoirs of the USSR, their fauna and flora, Uchpedgiz, 1961.