Radiological hazard indices due to activity concentrations of natural radionuclides in farm soils from two high background radiation areas in Nigeria

Abstract

Abeokuta and Jos Plateau, towns in the southwestern and northern parts of Nigeria, respectively, are situated in areas of high background radiation. The use of farm soil for the construction of dwellings by local residents and for agricultural purposes in these areas may present scenarios for both enhanced external and internal exposure pathways to the population. In order to assess the gamma radiation exposure levels, soil samples from 65 farms in Jos Plateau and 47 farms in Abeokuta were collected. Using gamma-ray spectroscopy the activity concentrations of 226Ra, 232Th and 40K in the samples were determined. From the activity concentrations of these radionuclides, the absorbed gamma dose rates were calculated. The obtained mean total absorbed gamma dose rates varied between 194 ± 59 nGy h−1 and 350 ± 270 nGy h−1 in Jos Plateau, whereas in Abeokuta, it was 167 ± 140 nGy h−1. These results, along with the results of the estimated annual effective dose rates, radium equivalent (Raeq), external hazard index (Hex), internal hazard index (Hin) and gamma index (Iγ), are presented in this paper. The results of this study indicate that the populations in the investigated areas are likely subjects for high radon burden in their dwellings.