Abstract
The Yertis (Irtysh) river is the largest left tributary of the Ob. The river is 4.248 km long and flows through the territories of three countries: China (618 km), Kazakhstan (1.589 km), and Russia (2.041 km). The purpose of this study is to analyze the concentrations of Hg, Cd, Pb, Cu, Zn in the surface waters of the transboundary river Yertis in comparison with the clarkes of elements in the hydrosphere, their spatial distribution, and change over time. The survey was conducted at six observation points within the Republic of Kazakhstan: Boran village, Ust-Kamenogorsk city, Predgornoe village, Semey city, Aksu city, Pavlodar city. The analysis of available information has allowed obtaining heavy metals distribution in space and change in time. The increased content of Hg, Cd, Zn was determined in the surface waters of the Yertis river in relation to clarkes of the hydrosphere. At the same time, a decreased content of Pb and Cu was found. The highest values of clarke concentration of elements were Cd (7), Hg (2.6), and Zn (1.7). Consequently, heavy metals have the greatest interest because their high levels in water have toxic effects on hydrobiont and benthic communities and on human health, who use these waters for household purposes.