Abstract
Reclaimed and conserved uranium mining sites continue to exert a significant impact on the environment even after the cessation of mining activities, particularly on surface water bodies. This study evaluates the influence of the conserved Shantobe uranium mine, located in the Akmola Region, on the contamination of the Kutunguz River with natural radionuclides. In most water samples from the Kutunguz River, gross alpha activity exceeds both national drinking water sanitary standards and the guideline values recommended by the World Health Organization (WHO). Gross beta activity in all water samples remained below the regulatory (screening) limits. Analysis of radionuclide concentrations in river water revealed that, in particular at sampling point No. 3, uranium isotope levels are significantly elevated compared to the background site, with 234U concentrations higher by a factor of 9 and 238U by a factor of 19. The distribution coefficients between bottom sediments and water indicate high mobility of uranium isotopes in the aqueous phase, whereas radium isotopes tend to accumulate predominantly in bottom sediments and show a weak correlation with their concentrations in water.The results of this study highlight the necessity for long-term monitoring of the river (seasonal and sequential) and confirm the radioecological impact of the region’s “uranium legacy” on aquatic ecosystems.