SPATIAL-TIME VARIABILITY OF THE LEVEL OF HEAVY METAL COMPOUNDS IN THE WATER OF THE MALKA AND BAKSAN RIVERS

Introduction. The quality of water today, especially fresh water, has become one of the most important factors in the health of the population. All over the world, the greatest danger to land waters is the pollution of water with heavy metal compounds, since they do not undergo biodegradation and have the ability to accumulate in various components of the ecosystem. Along with the establishment of concentrations, it is of particular importance to study the general regularities in the distribution of heavy metal compounds in individual areas of water bodies during the main phases of the water regime. Materials and methods of the research. River water samples were taken in the period 2005-2019 during the main phases of the water regime - winter low-water period and at the peak of high water. When taking water samples, the temperature of air, water and transparency were recorded. Under stationary conditions, the pH value was measured in all the samples taken. The samples were preserved with nitric acid. Determination of the content of dissolved forms of heavy metal compounds (Cr, Ni, Mo, Mn, Zn, Pb, Cd) was carried out by the atomic absorption method using a spectrometer with electrothermal atomization "MGA-915M". The results of the study and their discussion. This article presents the results of long-term observations to identify the degree of water pollution in the Malka and Baksan rivers with compounds of heavy metals such as chromium, nickel, molybdenum, manganese, zinc, lead and cadmium (Cr, Ni, Mo, Mn, Zn, Pb, Cd). The content of dissolved forms of heavy metals in the water of the studied rivers is subject to significant spatial and seasonal variability: the concentration values in the lower reaches of the rivers are much higher than the average, with the exception of molybdenum compounds in the water of the Baksan River. An increased content of dissolved forms of heavy metal compounds in the water of rivers during the summer flood is characteristic, when the rivers pass to ground water, the concentrations decrease by 1.5-2 times. Conclusions. The observed maximum values of the concentrations of heavy metal compounds in river water during the summer flood are obviously explained by the slope processes of the washout of loose detrital material by melt water of glaciers and snow, ground and surface waters. These processes uncontrollably form the level of heavy metal compounds in river water. The revealed levels of heavy metal compounds in river water for the studied long-term period, as well as the frequency of cases of exceeding the maximum permissible concentrations are illustrated by graphs.

Rivers Malka and Baksan, heavy metal compounds, pollutants, middle course, lower course of rivers, main phases of the water regime

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