Assessing Scalability of Natural Radionuclides and Associated Risks in Soils from Gold Mining Areas in Iperindo, Southwestern Nigeria

The environmental and health implications of artisanal gold mining activities at mining sites across Nigeria have rekindled research interest. This study aimed to assess the scalability of naturally occurring radioactive materials in gold mining sites in Iperindo, Nigeria. Soil samples were collected from three different mining sites and control locations and analyzed for natural radionuclides, mainly ²³⁸U, ²³²Th, and ⁴⁰K, using gamma spectrometry having a sodium iodide detector. The average activity concentration values of 61.55 ± 3.71, 72.65 ± 4.45, and 1134.99 ± 38.12 Bqkg⁻¹ obtained from within the mining sites for ²³⁸U, ²³²Th, and ⁴⁰K, respectively, were above the world permissible values of 33.0 Bqkg⁻¹ for ²³⁸U, 45.0 Bqkg⁻¹ for ²³²Th, and 420.0 Bqkg⁻¹ for ⁴⁰K. The average activity concentration values of 15.26 ± 3.19, 21.46 ± 4.27, 381.04 ± 23.36 Bqkg⁻¹ estimated for ²³⁸U, ²³²Th, and ⁴⁰K, respectively, for the control location were, however, lower than the global permissible values. The study also evaluated other radiological parameters such as radium equivalent, dose rate, annual effective dose rate, internal and external hazard indices, and alpha and gamma indices. The obtained values were 252.83 Bqkg⁻¹, 119.98 nGyh⁻¹, 147.15 mSvy⁻¹, 0.85 Bqkg⁻¹, 0.68 Bqkg⁻¹, 0.31 Bqkg⁻¹, and 1.89 Bqkg⁻¹ respectively. Except for radium equivalent, external and internal hazard risks, and alpha index, which were significantly lower than the recommended threshold, all other radiological parameters were higher than the recommended global limits. Moderate data reproducibility and a p-value of 0.000574 further reinforced the robustness and reliability of the results obtained in this study.