State of the surface waters in the Mesta River basin, after the reclamation of the Eleshnitsa uranium deposit

Abstract

In the period from 1955 to 1992, uranium ore was mined and processed in the Mesta River basin around the village of Eleshnitsa, region of Razlog. The ore processing plant was built and a tailings storage facility was built next to it. In the period 2002–2006, the tailings storage was reclaimed, and in 2011–2012 the ore mines were also reclaimed. For the treatment of drainage water, a treatment plant was built in the valley of Valchoto Dere River, a left tributary of the Mesta River. The radiological monitoring carried out by the Basin Directorate “West Aegean Sea Region” reveals a generally good quality of the surface waters in terms of the content of uranium and radium (226Ra) outside the area of the former uranium mining and the tailings storage facility. In this area, in some years a high content of natural uranium was found, with concentrations from 0.54 to 67.40 mg/l on average per year. The values significantly exceed (by 1.8 to 224.6 times) the norm regulated in the regulation for radiation protection and safety from the liquidation of the consequences of uranium mining. The spread of uranium is limited to a small area shortly downstream from the sources of contamination, but the potential risk to the local ecosystem should not be neglected. Radium, in contrast to uranium, has concentrations below the permissible limits in the twelve years studied. Its content varied from 0.025 to 0.11 Bq/l on average annually. The results show that the Mesta River near the border with the Republic of Greece is not contaminated with the studied radionuclides.