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.
