Assessment of environmental and radiological risks in mining-affected areas of Minna, Niger State, Nigeria

Mining is a human activity that perturbs radionuclide distribution in the natural environment. Minna area of Nigeria is rich in gold deposit and mining activity is active in the area. In this study, radiological impact of mining on human and non-human biota was assessed using airborne gamma ray spectrometric data of study area. The elemental concentration of naturally occurring radioactive materials (NORMs) in (%) for potassium, (ppm) for equivalent thorium and uranium were converted to activity concentrations in (Bq Kg −1 ). The activity concentrations were used to evaluate the human risk factors and estimate dose on non-human biota. Estimated absorbed dose rate \((\text{A}\text{D}\text{R})\) range from 20.78 to 86.62 \({\text{n}\text{G}\text{y} \text{h}}^{-1}\) with an average value of 43.00 ± 14.9 \({\text{n}\text{G}\text{y} \text{h}}^{-1}\) , annual effective dose equivalent for indoors and outdoors \({(\text{A}\text{E}\text{D}\text{E}}_{\text{i}\text{n}},{\text{A}\text{E}\text{D}\text{E}}_{\text{o}\text{u}\text{t}})\) were estimated ranging from 0.102 to 0.425 \({\text{m}\text{S}\text{v} \text{y}}^{-1}\) and 0.025–0.106 \({\text{m}\text{S}\text{v} \text{y}}^{-1}\) respectively. Annual gonadal dose equivalent \((\text{A}\text{G}\text{D}\text{E})\) and excess lifetime cancer risk \((\text{E}\text{L}\text{C}\text{R})\) were estimated ranging from 145.24 to 612.66 \({\upmu \text{S}\text{v} \text{y}}^{-1}\) and (0.36–1.48) × 10 −3 respectively. The peak values of estimated radiological hazards indicators exceeded the world average value of 59.00 \({\text{n}\text{G}\text{y} \text{h}}^{-1}\) , (0.41, 0.07) \({\text{m}\text{S}\text{v} \text{y}}^{-1}\) , 300 \({\upmu \text{S}\text{v} \text{y}}^{-1}\) and \({0.29\times 10}^{-3}\) for ADR, \({(\text{A}\text{E}\text{D}\text{E}}_{\text{i}\text{n}},{\text{A}\text{E}\text{D}\text{E}}_{\text{o}\text{u}\text{t}})\) , \(\text{A}\text{G}\text{D}\text{E}\) and \(\text{E}\text{L}\text{C}\text{R}\) respectively. The results imply averagely low radiological risk for human populace; however, a potential risk is anticipated for areas of peak occurrence of estimated parameters. Risk quotients below the hazard threshold value of 1.0 were estimated in the assessment of radiation dose impact on non-human biota, indicating low risk. The radiological parameters mapped with elevated values were within Nabi, Nadna, Buslimi, Shiroro, Barga, Guni, Dandawa and Fuka. This study showcases a baseline of moderate radiological impact in the study area. Periodic monitoring is advised as mining activities are predicted to intensify.