Assessment of radionuclide concentration and associated risks in soils from Iperindo mining sites, Nigeria

The assessment of natural radionuclides in soil samples from artisanal gold mine sites in Iperindo, Nigeria was conducted using different analysis methods. Soil samples collected across three locations and within a control area were analyzed using well-calibrated gamma spectroscopy fitted with a sodium iodide detector. The average activity concentrations (ranges) of ²³⁸U, ²³²Th, and ⁴⁰ K were found to be 61.55 ± 13.97 (33.40–87.00) Bqkg⁻¹, 72.65 ± 16.83 (41.90–105.10) Bqkg⁻¹, and 1134.99 ± 142.24 (720.50–1722.10) Bqkg⁻¹, respectively for the mining areas and 15.26 ± 6.96 (10.90–20.10) Bqkg⁻¹, 21.46 ± 9.35 (17.40–25.30) Bqkg⁻¹, and 381.04 ± 51.27 (280.30–511.70) Bqkg⁻¹, respectively for the control locations. The average activity concentrations of the radionuclides assessed were above the worldwide permissible limits for the Iperindo mining areas and below the worldwide average for the control areas. The investigation also assessed various radiological parameters, encompassing the radium equivalent, dose rate, annual effective dose rate, internal and external hazard indices, alpha and gamma indices, annual gonadal equivalent, and excess lifetime cancer risk. The recorded values for mine locations were 252.83 Bqkg⁻¹, 119.98 nGyh⁻¹, 0.15 mSvy⁻¹, 0.85 Bqkg⁻¹, 0.68 Bqkg⁻¹, 0.31 Bqkg⁻¹, 1.89 Bqkg⁻¹, 850.23 μSvy⁻¹, and 0.52 × 10⁻³, respectively. Except for the radium equivalent, external and internal hazard risks, and the alpha index, which were notably below the recommended threshold, all the other radiological parameters exceeded the globally advised limits. All the radiological parameters from the control areas were below the worldwide average values.