Impact of Natural Radioactivity (Uranium, Thorium and Potassium) and Toxic Heavy Metals Contents in Water and Sediments from North Africa Dams (Algeria and Tunisia): Geochemical Behavior and Environmental Implications

Abstract

Natural radioactivity of 238U, 232Th and 40K for water and sediment samples collected from Sidi Salem dam (Tunisia) and Aïn Dalia dam (Algeria) were measured using TERRA detector of rays (gamma, beta, and alpha), Gamma-ray spectrometry and atomic absorption spectroscopy were used to analyze the levels of radionuclides and heavy metals, respectively. Heavy metals (Fe, Pb, Zn, Ni, Cu, Cr and Cd) and associated health risks in surface water and sediment of dams have been investigated in this study. The mean activity concentrations in the water samples were 1.72±0.01, 0.068±0.01 and 94.6±1.04 Bql-1 for 238U, 232Th and 40K respectively (Tunisia dam) and were 1.9± 0.24, 0.09±0.01 and 131.43±1.03 Bql-1 for 238U, 232Th and 40K respectively (Algeria dam). The mean activity concentration of 238U, 232Th and 40K measured in the sediment samples were 2.67±0.01, 0.18±0.012 and 197.87±2.01 Bqkg-1 respectively (Tunisian dam) and were 4.34±0.05, 0.27±0.05 and 287.61±3.34 Bqkg-1 respectively (Algeria dam). The activity concentration of 40K was higher than that of 238U and 232Th for the water and sediment samples. The mean activity concentrations follow the order 40K > 238U > 232Th. The mean concentrations of the heavy metals decreased in this order Fe > Pb > Zn > Ni > Cr > Cu > Cd. All measured activity concentrations and estimated radiological parameters were below world permissible limit values. Therefore, there may be no serious immediate radiological health burden on the environment and the people using the damage.