Radiological Hazard Indices and Environmental Impact of Primordial Radionuclides in Iyin Quarry Site and Araromi-Iyin, Southwest, Nigeria

Abstract

The terrestrial radionuclides content of Araromi-iyin and Iyin quarry site was measured with handheld RS-125 super spec gamma-ray spectrometer using forty sampling points in each of the location of the study area. The purpose of the study is to determine the concentration of ²³⁸U, ²³²Th and ⁴⁰K in the ambient air and thereby estimate the absorbed dose rate and evaluate the radiological parameters in order to assess the possible radiation risk to the dwellers in the communities. Analysis of the results show that the mean concentrations of ²³⁸U, ²³²Th and ⁴⁰K were 39.80, 69.62, and 939.0 Bq/kg and 49.28, 112.55, and 1,270 Bq/kg for Araromi-iyin and Iyin quarry site respectively. The mean value of the absorbed dose rate for the two locations were 102.53 nGy/h and 149.43 nGy/h accordingly. The outdoor and indoor effective dose for the two locations were 0.13 & 0.05 mSv/y for Araromi-iyin and 0.13 and 0.68 mSv/y for Iyin quarry site. The external and internal hazard index for Araromi-iyin were 0.73 and 0.83 and Iyin quarry site were 0.83 and 0. 97. The annual gonadal index has the mean value of 0.71 and 1.02 for Araromi-iyin and Iyin quarry site while that of radium equivalents were 205.75 and 300.08 Bq/kg accordingly. The gamma representative indices were 0.79 and 1.15 and excess lifetime cancer risk were 0.36 and 0.52 for Araromi-iyin and Iyin quarry site respectively. The measured radionuclide contents, the effective dose, and the excess lifetime cancer risk were higher than the world limit in both locations. The annual gonadal index and the gamma representative index in Iyin quarry sites were higher than the world limit. The concentration of measured radionuclides and estimated radiological parameters in Iyin quarry site were higher than that of Araromi-iyin. There is need for more scrutiny of Araromi-iyin community while the ongoing mining in the quarry site is impacting the radioactivity level of Iyin quarry site and environs.