Assesment of naturally occurring radionuclides in the environs of a Bauxite mining company in Sierra Leone

This study was carried out to determine the activity concentrations of naturally occurring radionuclides in water and soil from the environs of Gondoma, Mokanji Sierra Mineral Holdings Bauxite Mines and to estimate the possible exposures to both the mine workers and members of the community living in the vicinity of the mines. Gamma spectrometry measurements was used to ascertain the radioactivity levels of naturally occurring materials (NORM). The average activity concentration of ²²⁶Ra, ²³²Th and ⁴⁰K in the water samples were 2.2 ± 0.53 Bql^-1 (in a range of 0.6-4.8), 1.76±0.13 Bql^-1 (in a range of 1.1-2.2 Bql^-1)and 53.83 ± 4.46Bql^-1 (in a range of 9.6-92.1 Bql^-1)respectively. The World Health Organization (WHO) recommended guideline levels of ²³⁸U (Ra-226) and ²³²Th in drinking water are 10.0 Bql^-1 and 1.0 Bql^-1 respectively. The activity concentrations of ²³⁸U (Ra-226) in all the water samples had values below the recommended guideline level. However, the activity of ²³²Th in all water samples have higher concentrations above the recommended guideline of WHO. The soil samples average values of ²²⁶Ra, ²³²Th and 40K were 56.0 ± 1.7 Bqkg^-1 (in a range of 50.3-60.0), 69.4 ± 1.43 Bqkg^-1 (in a range of 45.3 - 99.0 Bqkg^-1) and 1072± 6.0 Bqkg^-1 (in a range of 1304-1856.2Bqkg^-1) respectively. The world average values in normal areas according to UNSCEAR 2000, are ²³⁸U (²²⁶Ra), 30 Bq/kg; ²³²Th, 35 Bq/kg; and ⁴⁰K, 400Bq/kg.This shows that the values of soil are all above recommended guideline. It is therefore recommended that further studies be carried out to establish average activity concentrations of the study areas and where possible, a radiation program be developed and established to ensure protection and safety of the mine workers and public. (author)