Investigation of isotopic ratio (234U/238U), chemotoxicity and radiotoxicity of dissolved uranium in selected groundwater of Bangladesh

The activity concentrations of U-238 and U-234 in groundwater samples collected from different locations in Bangladesh were measured by alpha spectrometric method. Activity concentrations of U-238 and U-234 were found to be 4.76-8.22 mBqL(-1) and 3.24-6.48 mBqL(-1) respectively. The calculated U-234/U-238 isotopic ratio varied from 0.58 to 0.94, suggesting that most of the groundwater exhibit nuclear disequilibrium (U-234/U-238 < 1). Isotopic ratio of U-234/U-238 less than unity in groundwater could be related to the (')alpha-recoil emplacement' mechanism of daughter nuclides. In this study, the radiotoxicity and chemotoxicity risk of dissolved uranium in groundwater were calculated. The average ingestion dose of U-234 and U-238 for infants, children, adults were found to be 0.06, 0.09, 0.18 mu Svy(-1) and 0.08, 0.11, 0.22 mu Svy(-1) respectively.