Evaluation of natural radioactivity and its associated health hazard indices of a South Indian river

Abstract

The activity concentration of the natural radionuclides 226Ra, 232Th and 40K was measured for sediment samples collected from thirty-three different locations along the Bharathapuzha river basin by using high-resolution gamma-ray spectrometry. The concentrations of the natural radionuclides were found to vary from location to location, and their mean values are 19.6, 82.87 and 19.44 % higher than the worldwide mean values of 226Ra, 232Th and 40K, respectively. The value of 232Th was found to be higher than that of 226Ra in 82 % of the samples collected for this study. The calculated values of indoor gamma dose rate (DIN) ranged between 89.55 and 194.24 nGy h-1, and the overall mean value is 63.2 % higher than the recommended safe and criterion limit by UNSCEAR. The internal and external hazard indices (Hin and Hex), the representative gamma index and alpha index (Igamma and Ialpha), the annual gonad dose equivalent (AGDE) and the excess lifetime cancer risk (ELCR) were also calculated and compared with the international recommended values. Multivariate statistical analyses were also carried out to determine the relation between the natural radionuclides and various radiological parameters.