Dynamics of concentrations changes of heavy metal group pollutants in surface water of the transboundary Ertis River on the territory of the Republic of Kazakhstan. JGEM [Internet]. 2020 Oct. 20 [cited 2026 Jul. 20];57(2):54-68. Available from: https://bulletin-geography.kaznu.kz/index.php/1-geo/article/view/898