NATURALLY OCCURRING RADIONUCLIDES AND THEIR RADIOLOGICAL RISK ASSESSMENT IN RIVER SEDIMENTS FROM THE DITRAU ALKALINE MASSIF

Abstract

Naturally occurring 238U, 232Th and 40K radionuclides within river bed sediments of Jolotca and Ditrău rivers from Ditrău Alkaline Massif (DAM) and their environmental risk and spatial distribution have been analyzed. The DAM metamorphic formations have been the subject of multiple studies due to their structure and high variety of mineral species. This led to the execution of many mining operations. River bed sediment samples have been collected from two of the main drainage basins of DAM, Ditrău and Jolotca rivers. The samples were analyzed using gamma-ray spectrometry in order to determine the concentration of the naturally occurring radionuclides and the risk parameters such as RLI (Representative level index), AGDE (Annual gonadal dose equivalent), Hex (External hazard index), Hin (Internal hazard index) and DR (absorbed gamma dose rates in air). 238U, 232Th and 40K show values higher than the Upper Continental Crust (UCC) and other studies from around the world. DR, AGDE and RLI are higher than the global average and the safe limits. These values are a consequence of the geological context which determined the presence of heavy minerals and Th and U bearing minerals.