Determining the Chernobyl impact on sediments of a pre-Alpine lake with a very comprehensive set of data

Man-made and natural radionuclides in Lake Wallersee were determined in the pre-Alpine environment at the northern slope of the Alps, which was heavily affected by the Chernobyl fallout in May 1986. The objective of this study was to get knowledge of location and quantity of man-made radionuclide input (especially 137Cs) generated in the Chernobyl accident to lake sediments. Eleven sediment cores were sampled and activity depth profiles of 137Cs and 210Pb were determined with 5 mm depth-resolution. The Chernobyl fallout produced an extreme 137Cs peak in the sediment cores providing an excellent time marker. The chronological interpretation of deeper sediment layers was done by radiochemical analysis of 90Sr and 239+240Pu, which were released during atmospheric weaponsʹ tests in the 1950s and 1960s. This allowed a complete chronological analysis of the sediment cores with a very compact set of data.