Evaluation of 210Po and 210Pb in some mineral spring waters in Brazil

Aalysis of most natural waters shows that 210Po, the last radioactive member of the uranium natural decay-series, is present at very low activities, usually lower than its insoluble precursor, 210Pb. Recent papers, however, show that 210Po can exist at very high concentrations in groundwaters of some shallow aquifers. Concentrations of 210Po and 210Pb have been analyzed in the mineral spring waters of a high background region of Brazil: Águas da Prata. The water samples were collected over a period of one year in springs used by the local population and tourists to the region. Concentrations ranging from <3•5 mBq l-1 to 7•80×1022 mBq l-1 and from 3•0 mBq l-11 to 3•98×102 mBq l-1 were observed for 210Pb and 210Po, respectively. Doses were estimated in order to evaluate the relative importance of the ingestion of such radionuclides. Based upon measured concentrations, effective doses up to 1•8×10-1 mSv y-1 were observed for 210Pb and 210Po. Doses up to 5•9 mSv y-1 for the ingestion of 210Pb and up to 1•9 mSv y-1 for the ingestion of 210Po were obtained for the critical organs