Estimation of the capacity for self‐purification of transformed rivers of Khanty‐Mansi Autonomous Okrug‐Yugra (Russia).

This article focuses on assessing the self-purification capacity of rivers in the Ob River basin within the Khanty-Mansi Autonomous Okrug–Yugra, a region heavily impacted by oil and gas industry activities. Using the coefficient of mineralization—defined as the ratio of nitrogen-consuming bacteria to saprophytic bacteria—the study analyzed microbial communities in river water samples collected during 2003–2006 and 2018–2019. Results showed that 75–79% of rivers draining oil field areas exhibited low self-purification potential, linked to disturbances in microbial community structure and accumulation of hard-to-mineralize organic matter. Only about 23% of rivers demonstrated sufficient self-purification capacity, notably the Ai-Pim and Ovyn’yegan rivers, which maintain ecological balance. The study recommends incorporating microbiological parameters into water quality monitoring to better detect pollution impacts and support water resource management aimed at reducing ecological risks in the Ob River basin and the Arctic region.