Effect of Heavy Metal Concentration on Natural Radioactivity Levels in Selected Wetlands in Kampala, Uganda.

Abstract

Top soil samples and accompanying yams were analyzed for natural radionuclide constituents and heavy metal concentrations using gamma - ray spectrometric methods and atomic absorption spectrometery (AAS), respectively. The results indicated that Mercury (Hg) had relatively low concentrations compared to Lead (Pb) in the yams but these were still above the world average values in all the wetlands. According to the results of this study, mean activity concentrations of the radionuclides increased according to the order 232Th > 226 Ra > 40 K. γ-ray spectrometric analysis indicates that the activity concentrations of Radium ( 226 Ra), Thorium ( 232 Th), were all higher than the world average values for soil, while the activity concentrations of Potassium ( 40 K), are lower than their corresponding world average values. The dose rates at 1 m above the ground level and the corresponding biological effective dose rates were estimated. Pearson correlation coefficients were determined among heavy metal concentrations and the activity concentration of naturally occuring radionuclides. The values obtained were compared with values from other locations around the world. The ranges and mean values of all the radiation hazard parameters considered in this study do not show any significant departure from the values obtained for areas with normal background levels around the world.