EVIDENCE OF TC-99 IN URAL RIVER SEDIMENTS

Sediments collected from the Techa River at Nadirov Bridge were analys ed for Tc-99. The maximum concentration was found at a depth of 14-18 cm. This layer was sedimented around 1950, i.e. at a time when the max imum releases of waterborne radionuclides occurred to the river from t he MAYAK plutonium production plant in the Urals. The vertical distrib ution of Tc-99 in sediments followed that of Cs-137, and the mean rati o between Tc-99 and Cs-137 in the sediments at the time of discharge w as 0.41 x 10(-3). Laboratory experiments showed that Tc-99 under anoxi c conditions, e.g. when organic material is decomposing, will be retai ned br sediments. (C) 1997 Elsevier Science Ltd.