Radionuclide Contamination of Surface Waters, Sediments, and Soil Caused by Coal Mining Activities in the ruhr District (Germany)

The discharge of highly mineralised mine waters with enhanced 226Ra and 228Ra activity concentrations has affected creeks, rivers, sediments, soils, and plants along the Lippe River and its tributaries. 226Ra activity concentrations were elevated in all water samples receiving mine water, with activity concentrations gradually decreasing with increased distance from the colliery due to dilution and chemical precipitation of radium with barium. Increased concentrations of radium and radium decay products were also measured in sediments and flood-affected soils. The sediments show an enrichment of 226Ra up to a factor of 750, while the contaminated soils “only” reach a factor of 10. In aquatic plants, a 4-fold increase in 226Ra activity concentrations was measured downstream of the discharge points. The contamination of the river banks and adjacent floodplain with radium is responsible for enhanced gamma dose rates, which, along with the incorporation of soil by playing children, provide potential radiation exposure to the public.