URANIUM IN THE FLOODPLAINS OF THE MULDE RIVER

At the time of the Warsaw Pact, the former German Democratic Republic (GDR) was the third largest producer of uranium in the world and the most important supplier of uranium for the USSR. The uranium industry was located at the Ore Mountains and its foreland. The mountain range of the Ore Mountains, which is located at the border between Saxony / Germany and the Czech Republic, was famous for its uranium deposits. Mine water, mine dumps and Tailings ponds from uranium mining and milling activities cause considerable intake of uranium into the Mulde River, which drains the Saxon part of the former uranium mining and milling areas. Today, clean-up of the legacy of the former uranium industry represents one of the largest remediation projects in progress.

This research project was established to quantify the long-term effect of the former uranium mining activities on the floodplain ecosystem of the Mulde River. The radiological impact from the agricultural use of the alluvial soils was investigated. More than 280 samples from different environmental compartments (river water [1], surface sediment from the river, alluvial soils and agricultural crops) were sampled and analysed by radiometric methods. All of the compartments still show an impact from the former uranium mining. However, comparisons with earlier measurements reveal a considerable decrease of the radionuclide contamination. Thus, it is not possible to relate the activities in the soil samples to the activities of the water and sediment samples measured in parallel. Radionuclides originating from the alluvial soils enter the human food chain as a result of the agricultural use of the floodplains. Yet, the radiological effect is small. The uranium contamination of the river water results in activity values lying beyond the threshold of the current German Drinking Water Ordinance. Dose calculations do not exceed the guidance level of 1 mSv additional potential radiation exposure per year for the current agricultural use, even assuming most unfavourable exposure sites.

References:

[1] S. Bister, F. Koenn, M. Bunka, J. Birkhan, T. Lüllau, B. Riebe, R. Michel, Uranium in water of the Mulde river, J Radioanal. Nuc. Chem. 2010, 286, 2, 367-372.