Anthropogenic influence on the state of Lake Shalkar in Western Kazakhstan

. Lakes are natural accumulating systems with slow water exchange, acting as a regulator of river systems. Small lakes, which include water bodies with a surface area of up to 10-50 sq. km, are found everywhere and are actively used for economic and recreational purposes. Lake Shalkar is located in Western Kazakhstan and is the “Pearl of Kazakhstan”, where there are many vacationers in the summer. The summer months are characterized by bright, dry weather. The average air temperature in the territory in July is 23.6°C, the absolute maximum temperature reaches 41-45°C. The article studies the ecological state of Lake Shalkar. Research was carried out on several parameters: the organoleptic and hydrochemical properties of the lake water were studied, as well as the anthropogenic impact on the lake, since the lake, due to its unique properties, has recreational significance. In this regard, field trips to the lake were organized during the summer resort campaign in order to identify the anthropogenic load on the lake. A decrease in water turbidity was observed in summer. According to the data obtained, water does not differ in smell and taste from year to year. On average, organoleptic indicators do not change much; the smell is salty, easily detected, and may be the reason that the water is undrinkable, but suitable for bathing. In Lake Shalkar, the average water temperature was 14.7, the hydrogen index was 6.33, the concentration of oxygen dissolved in the water was 10.16 mg/dm 3 BOD5 - 2.82 mg/dm 3 . Exceedances of the MPC were recorded for substances from the group of main ions (chlorides -6.7 MPC, sulfates -1.2 MPC).


Introduction
Environmental assessment of anthropogenic impact on the environment is relevant for the Republic of Kazakhstan.Anthropogenic interventions in the region lead to the depletion of natural resources, pollution of natural environment components and the formation of artificial landscapes.Anthropogenic activities affect the ecological state of mountain lakes around the world [1].The accelerating pace of global change has drawn attention to the cumulative impacts of new and extreme environmental changes (i.e., stressors), especially in marine ecosystems [2].Lakes are important natural resources that serve many functions that serve environmental and socio-economic purposes.Being closely connected with the environment, lakes are sensitive to external changes, and their current geochemistry reflects both natural and anthropogenic characteristics of the entire catchment area [3][4][5].Based on monitoring at various scales, it is clear that intense anthropogenic activities have led to severe degradation of inland waters in the last century, and due to massive nutrient inputs, eutrophication has become a serious environmental problem for lakes around the world.Although natural processes may be important, various anthropogenic influences are key factors influencing the current state of lakes [6][7].Currently, there is an increase in the volume of household waste and the formation of spontaneous landfills, which causes great damage to the environment.The problem of household waste and spontaneous accumulations can be solved in several ways: the use of preventive measures, accompanied by administrative measures and the injection of necessary investments with the support of local authorities for waste disposal, which will also help reduce the formation of spontaneous landfills [8].

Materials and methods
One of the main criteria of the aquatic environment is organoleptic and hydrochemical indicators.To determine hydrochemical parameters, the following methods were used:  Determination of pH of water according to GOST 26449.1-85(determination of pH of active reaction). GOST 4151-72 Determination of total water hardness. Determination of chlorides in water according to GOST 4245-72. GOST 4192 -82 Method for determining free minerals in water. GOST 4389-72 Method for determination of sulfates in water. GOST 18164-72 Method for determination of dry waste.

Results and Discussion
Lake Shalkar covers an area of 206 km in circumference, 19 km in length and 15 km in width.The water in the lake is salty.It contains hydrochloric acid, calcium bicarbonate, magnesium and other vital mineral elements.This means that its composition is no different from sea water, and its ecological status is superior to almost all sea waters.
The lake coast is formed by alluvial waters.The average depth of the lake is 5.34 m. (Figure 1)  The average January temperature is 11-14°C, sometimes drops to -40°C, the July temperature rises to 22-25°C, sometimes up to 40°C (Figure 3).According to the table, there is a decrease in water turbidity in the summer.On average, organoleptic indicators do not change much; the salty smell, easily detected, may be the reason that the water is unpleasant to drink.According to our studies, excess of MPC was observed in almost all summer months for the following indicators: dissolved oxygen, COD, suspended solids, hardness, mineralization, dry residue, calcium (exceedance only in July), magnesium, potassium.
During the summer, on average, 1,200 people come to Lake Shalkar to relax in one month.The entire population rests in the private sector without running water or sewerage.Without treatment, waste enters the reservoir.
During the study, as stated in the main objectives, the concentration of population on Lake Shalkar during the resort campaign, as well as the ecological state of the place, quantitative and qualitative control of waste types.
On July 24, 2022 (Sunday), a survey was conducted among vacationers, taxi drivers and yurt workers during a business trip to Lake Shalkar.The number of cars is more than 50, gazelles are about 10, the number of vacationers is 200-250 people.No, why?) 0% 100% of vacationers believe that the lake's water is good for health and the lake needs to be turned into a recreational area; only 50% of respondents believe that the current state of the lake is suitable for recreation.But only 20% are satisfied with the conditions created on the lake, the remaining 80% believe that the rental of premises and conditions are not satisfactory.Garbage containers were also sorted to determine the predominant type of waste.Of all types of food waste, plastic bottles and food scraps account for the largest portion.Garbage collection occurs once a week and the garbage is not sorted.

Conclusion
According to our studies, excess of MPC was observed for the following indicators: dissolved oxygen, COD, suspended solids, hardness, mineralization, dry residue, calcium (exceedance only in July), magnesium, potassium.
No ammonium ions were detected, sulfate does not exceed the maximum permissible concentration.Chloride exceeds 485.0 in July and 454.0 in August.
The reduction in the concentration of pollutants with this type of water use and waste disposal is assumed to be 98% (2% enters the lake).Of all types of food waste, plastic bottles and food scraps account for the largest portion.
Also, as a result of anthropogenic impact on Lake Shalkar, its fish resources have reduced their production potential.If we evaluate the situation as a whole, it should be recognized that the level of anthropogenic pollution with human waste products (waste from industrial agriculture, the consequences of a large influx of tourists in the summer) leads to changes in the state of the aquatic environment for fish habitat, negatively affects the productivity of fishing, and leads to reduction in fish catches.

Table 1 .
Organoleptic indicators of water quality for 2022.

Table 2 .
Hydrochemical indicators of Lake Shalkar by month for 2022.

Table 3 .
Results of a survey of vacationers.

Table 4 .
Household waste during inspection of the shore of Lake Shalkar on average per month, 2022.