The intensive development of industry, transportation, and overpopulation in several areas of the Chui Valley has led to significant pollution of the hydrosphere. Pollution of surface waters is the process of changing the physical, chemical, or biological properties of natural waters upon the introduction of various substances that can have harmful effects on humans and nature. Any compound that disrupts norms and deteriorates water quality is considered a water pollutant.
Water quality is a characteristic of the composition and properties of water that determines its suitability for specific types of consumption. The main indicators of water quality include composition, total content, color, odor, taste, hardness, alkalinity, and the presence of iron, manganese, and some other elements.
The primary cause of the current degradation of natural waters is anthropogenic pollution. The main sources are:
• industrial wastewater;
• communal wastewater from cities and other settlements;
• runoff from irrigation systems, surface runoff from fields and other agricultural objects;
• atmospheric deposition of pollutants onto the surfaces of water bodies and watersheds.
Depending on the conditions of formation, wastewater is divided into three groups:
• domestic wastewater - runoff from showers, laundries, baths, canteens, toilets, floor washing, etc. Their average volume is 0.5-2 l/sec. From 1 hectare of residential development, they contain approximately 58% organic and 42% mineral substances;
• atmospheric wastewater, or stormwater. Their runoff is uniform: once a year - 100-150 l/sec per hectare; once every 10 years - 200-300 l/sec per hectare. Stormwater runoff from industrial enterprises is particularly dangerous. Due to their irregularity, the discharge and treatment of these effluents are complicated;
• industrial wastewater - liquid waste generated during the extraction and processing of raw materials. Water consumption in this case is calculated based on specific water consumption per unit of production.
The most dangerous pollutants include heavy metal salts, phenols, pesticides and other organic toxins, petroleum products, synthetic surfactants (SAS), and other detergents, as well as mineral fertilizers.
In the waters of the rivers in the Chui basin and major tributaries, there is an increased concentration of pollutants: petroleum products, phenols, pesticides, and heavy metals. In the water of the Chu River, in the upper reaches (village of Orto-Tokoy), the concentration of pollutants is at background levels, with phenols and petroleum products absent. In the waters of the Chu River, after the inflow of wastewater from Bishkek (village of Vasilyevka), the concentration of phenols increases 8 times compared to the upper reaches (village of Orto-Tokoy), and petroleum products increase 7 times, etc. It has been established that 1 m³ of untreated wastewater, on average, pollutes 10-15 m³ of clean water.
It should be noted that at the beginning of the century, science was aware of only 17 pollutants in natural waters, whereas now there are more than 2,500 worldwide. This has a detrimental effect on public health and leads to the death of fish, waterfowl, and other animals.
The dynamics of discharges into surface water bodies of the most characteristic harmful substances in thousand tons per year are presented in the table (for the Chui Valley according to the national report on the state of the environment for 1997)
A serious situation with nitrate pollution of groundwater has developed in the area of the Orto-Alysh water intake, which provides 60% of the capital with drinking water. Elevated concentrations of nitrates have been observed at a depth of 150 m. This pollution is associated with the placement of livestock facilities in the sanitary protection zones of the water intake, the development of irrigated agriculture, poor sanitary conditions in settlements, and the lack of water supply and sewage systems.
In the southwestern part of the city of Kara-Balta, groundwater pollution with nitrates and manganese is noted due to leaks from previously contaminated industrial effluents from the tailings storage of the Kara-Balta mining and metallurgical plant.
Geoecological requirements for the protection of water bodies
The most effective form of protection for water bodies from pollution is waste-free technology. The term waste-free technology was first proposed by Russian scientists N.N. Semyonov and I.V. Petryanov-Sokolov in 1982. According to the resolution of the UN Economic Commission and the Declaration on low-waste and waste-free technologies and waste utilization, the following formulation of waste-free technology (WFT) is accepted: "Waste-free technology is the practical application of knowledge, methods, and means to ensure the most rational use of natural resources and energy within the framework of human needs and to protect the environment."
Thus, waste-free technology should be understood as a set of measures in technological processes that allows minimizing harmful discharges and reducing the impact of waste on water resources to acceptable levels.
It is important to remember (L.A. Muravya, 2000) that assessing the degree of waste-free production is a very complex task, and there are no unified criteria for all industries.
The main principles for creating waste-free production (A.A. Muravya, 2000, p. 118) include the comprehensive use of raw materials, the creation of fundamentally new and improvement of existing technologies, the establishment of closed water and gas circulation cycles, cooperation between enterprises, and the creation of production-territorial complexes.
Passive methods of protecting water bodies include a set of measures to limit discharges of domestic wastewater, industrial, and agricultural runoff into water bodies.
Natural waters - rivers are capable of self-purification and establishing biological balance. This occurs as a result of the combined action of physical, chemical, and biological factors. Physical factors include the intense flow of rivers, which ensures good mixing and reduction of suspended particle concentrations, the settling of insoluble sediments, the impact of ultraviolet radiation from the sun, etc. Among the chemical factors, the oxidation of organic and inorganic substances should be highlighted. Aquatic biocenoses play a decisive role in the self-purification of water bodies. Aquatic organisms collectively ensure multi-stage mineralization of organic matter through trophic links and its transfer to bottom sediments.
However, the ability of water bodies to self-purify is not limitless. At a certain level of pollution, especially during emergency, pulse discharges of untreated wastewater, all biota in the water body can be destroyed. Technogenic pollution of rivers and lakes has reached such scales that in many areas it exceeds their self-purification capacities. Due to ineffective wastewater treatment, a significant portion of nutrients - nitrogen, phosphorus - enters water bodies. A large amount of soil, organic matter, and mineral fertilizers is washed into water bodies from agricultural areas during floods and after heavy rains. Excessive enrichment of water bodies with biogenic substances leads to their eutrophication, i.e., a sharp increase in biological productivity and mass reproduction of phytoplankton, primarily of unpretentious blue-green algae.
In addressing the issue of protecting surface and groundwater in the Chui Valley, a priority direction should be, first of all, the exclusion of the discharge of collector-drainage waters and domestic wastewater into water bodies and rivers. It is especially important to regulate water use in the most water-intensive sectors of the economy.
Hydrotechnical engineers and irrigation specialists in farms need to develop and control irrigation regimes, avoid excessive moisture, and secondary soil salinization. They must strictly monitor the norms of water consumption by users, as they pay money for water use.
The ecological and hygienic situation is also characterized by the availability of drinking water in sufficient quantity and of good quality. However, in some areas of the Chui Valley, there is a shortage of drinking freshwater. Moreover, about half of the tap water is supplied without adequate treatment, i.e., it is mineralized, contaminated with bacteria and microbes, and various chemical substances. Additionally, the water often contains microscopic blue-green algae, which can cause outbreaks of dysentery and other infectious diseases.
A significant amount of water for domestic needs in the Chui Valley is taken from surface sources (rivers). Therefore, before being supplied to the water supply system, it must not only be purified from various waste but also disinfected. The main methods used for this are chlorination and ozonation. Developed countries have long switched to ozonation as the most harmless method of disinfection. However, it is more expensive, so chlorination is still used in the region. However, this can lead to the formation of dioxins in drinking water - the most dangerous of all substances synthesized by humans. Even in very small doses, it causes various diseases. If we sum up all the consequences of consuming contaminated drinking water, it turns out that it is a direct or indirect cause of 70-80% of diseases.
To protect the population from various waterborne infections and diseases, many countries around the world have developed special ecological and hygienic standards for maximum permissible concentrations (MPC) of harmful chemicals and other substances in water used for domestic and drinking purposes. At lower doses (concentrations), substances do not have harmful effects, and their presence in the aquatic environment in amounts not exceeding these concentrations can be considered safe. Ecological and hygienic standards for MPC take into account the harmfulness of pollutants in the aquatic environment based on the following criteria: sanitary-toxicological (sensitivity of living organisms to the action of harmful substances), organoleptic (color, odor, taste of water, etc.), and public health. For each harmfulness criterion, a threshold (non-effective) concentration is determined. The lowest of these, corresponding to the harmfulness criterion, is accepted as the MPC.
Thus, ecological and hygienic standards for MPC allow distinguishing pollution levels that directly or indirectly affect the sanitary conditions of water use and public health. The levels of water pollution depend not only on public health but also on the economic interests of society as a whole.
More than half of the small towns and district centers in the Chui Valley do not have centralized sewage systems and treatment facilities. The domestic waste and industrial wastewater generated, which account for more than 27% of total wastewater, are annually accumulated in absorption or cesspools and disposed of in watershed areas or directly into water bodies. This pollutes soils, waters, and vegetation, increasing the risk of bacterial contamination of the population.
The government of the republic is taking serious measures to prevent the growing pollution of water bodies with wastewater. Currently, a transition to a system of maximum permissible emissions (MPE) is being implemented. The value of MPE is determined for each specific source of emissions, calculated so that the total emissions from all sources in the Chui Valley do not exceed the MPC standard. The use of MPE standards will facilitate planning and monitoring of environmental protection activities, increase the responsibility of enterprises for compliance with environmental requirements, and eliminate conflict situations.
• reduction of specific consumption of mineral fuel and raw materials per unit of production;
• economically justified reduction of raw material extraction volumes;
• exploration of new reserves of raw materials and energy carriers;
• reduction of losses during extraction, enrichment, and consumption of resources;
• expansion of the use of secondary raw materials;
• comprehensive use of extracted resources;
• maximum complete development of deposits;
• recultivation of lands disturbed during mining operations.
To reduce the harmful impact of open-pit mining on the environment, quarries are widely filled in or artificial water bodies are created on-site, and measures for land recultivation are undertaken. The task of recultivation is to restore disturbed lands for their inclusion in economic circulation (for arable land, water bodies, forests, etc.). The most common and ecologically effective method of recultivation at present is the creation of water bodies in quarry excavations and greening their shores. There are examples where areas of former developments, after restoration measures, are used as recreational zones.
There are two main stages of recultivation: mining-technical and biological. The goal of mining-technical recultivation is to prepare the territory for development. This involves planning dumps, shaping slopes for convenient use, applying a layer of fertile soil previously removed from areas designated for construction, and carrying out flooding, industrial development, reclamation works, etc. At the biological recultivation stage, measures are taken to restore soil fertility.
Land recultivation is a complex problem. It largely depends on the specific ecological conditions of the disturbed territories. To design recultivation works, it is necessary to know the physical and chemical composition of the soil, the characteristics of the hydrological regime, the shape of dumps, slopes, etc.
At the current stage of societal development, the demand for mineral raw materials is increasing throughout the Chui Valley, which necessitates strict compliance with environmental protection standards and regulations during the extraction of various minerals and the development of mining industry projects. Hence, the first fundamental geoecological requirement for mining industry projects is a comprehensive approach to geological studies of mineral resources and the extraction of minerals.
A significant amount of damage to landscapes is caused by the careless attitude towards the extraction of construction materials and the use of valuable facing materials. All this is obviously explained by the lack of sufficiently specified norms and rules in state standards for the protection of mineral resources. Hence, the second geoecological requirement for the protection of mineral resources is the maximum ecological consideration in the design and construction, and operation of mining enterprises.