ASSESSMENT OF SOIL COVER CONTAMINATION BY POLYCHLORINATED BIPHENYLS IN THE ZHETYSU REGION

Abstract

The article presents the results of a study on the contamination of the soil cover of the Zhetysu Region of the Republic of Kazakhstan by polychlorinated biphenyls (PCBs). Soil samples were collected in 2024...2025 at 52 monitoring sites located in different natural and landscape zones of the region. The PCB content was analyzed using gas chromatography with an electron capture detector in accordance with the requirements of regulatory documents. The presence of polychlorinated biphenyls was detected in all studied soil samples. The total PCB concentrations ranged from 0.010 to 1.631 µg/kg. A significant diversity of individual congeners was identified, including indicator (“marker”) and dioxin-like compounds. The highest concentrations of the pollutant were recorded in soils of urbanized areas. A comparative analysis of the research results for 2024 and 2025 showed a noticeable decrease in PCB concentrations in 2025. This may be associated with seasonal features of sampling, redistribution of pollutants within the soil profile, and spatial heterogeneity of their distribution. The obtained results indicate a relatively low level of soil contamination in the region by polychlorinated biphenyls and can be used in organizing environmental monitoring of persistent organic pollutants within the framework of the Republic of Kazakhstan’s implementation of its international obligations under the Stockholm Convention.