Natural radionuclides, heavy metals and health risk assessment in surface water of Nkalagu river dam with statistical analysis

The concentrations of natural radionuclides (K-40, U-238 and Th-232), heavy metals (Pb, Ni, Cu, Cr and Cd) and associated health risk in surface water of Nkalagu river dam have been investigated in this study. Gamma-ray spectrometry and atomic absorption spectroscopy were used to analyze the levels of radionuclides and heavy metals, respectively. The mean activity concentrations of the radionuclides were found to be 120.45 +/- 6.51 Bq.l(-1) for K-40, 5.49 +/- 0.70 Bq.l(-1) for U-238 and 0.14 +/- 0.01 Bq.l(-1) for Th-232. The mean concentrations of the heavy metals decreased in this order Pb > Ni > Cr > Cu > Cd. The mean concentrations of both radionuclides and heavy metals, except for Cu, exceeded the World Health Organization permissible levels for drinking water. The radiological annual effective dose to the age groups, 0-1 yr, 1-2 yr, 2-7 yr, 7-12 yr, 12-17 yr and >17 yr, revealed a higher value in infants (0-1 yr) than the other age groups. This indicates that infants are the most vulnerable group to radiation hazard. The average daily dose and hazard quotient showed that the metals, Pb and Cd, are the major threat to adults and children. The hazard index revealed children are more liable to non-cancer effects through oral intake. (C) 2020 The Author(s). Published by Elsevier B.V. on behalf of African Institute of Mathematical Sciences / Next Einstein Initiative.