Evaluation of Radiological Hazard Indices and Environmental Safety in Soil Samples from Different Source Term Within the Tributaries of Awba Dam in the University of Ibadan

Abstract

Artificial and Natural radionuclides exist in environmental materials such as water, soil, rocks, and plant as well as in animals and human body tissues. Therefore, human being and environment are at constant radiation exposure. Regarding this, the present study aimed to determine the specific activities of radionuclides and perform the risk assessment study to establish if there was a potential threat posed by radionuclides to humans and aquatic life in Awba dam, the University of Ibadan, due to untreated effluents discharge from the hall of residences. In this study, natural and artificial radioactivity concentrations were determined in soil samples from different source terms located along the banks of the input water discharge points into Awba dam, University of Ibadan, were collected and analyzed for natural radioactivity level using gamma-ray spectroscopy. A total of Twenty-eight sediment samples were collected for the measurement. Samples were collected one after the other along the banks of the source point. Prior to the collection of all the samples from each source point, both analogue and digital survey meter were used to ascertain the level of radiation in their immediate environment. The prepared sample was sealed and stored for a minimum of thirty-days to allow for radium equilibration with daughters nuclide. The range of the activity concentration due to ${}^{40}K$ was 2.023 to 1194.1 $BqKg^{-1}$ while those for ${}^{238}U$ and ${}^{232}Th$ were respectively 2.12 to 21.82 and 0.91 to 31.10 $BqKg^{-1}$. The total absorbed dose rate of the three radionuclides are $0.08-8.54$, $1.0-10.01$, $0.26-10.56$ $nGy^{-1}$ respectively, for the result shows that the total concentration of ${}^{232}Th$ is much higher than that of ${}^{238}U$ while ${}^{40}K$ leads the table of radioactivity concentration. The entire soil sample from different source term does not pose any significant radiological threat to the general public, and the activity concentration of the radionuclides in the sediments are equally low. No artificial sources of radionuclides were detected in any of the soil and sediment samples of the Dam.