Assessment of Natural Radioactivity in Soil Samples Around Tin Mining Sites in Plateau State

Tin mining and columbite processing in Plateau State, North Central Nigeria, have left extensive tailings deposits and disturbed soils that may contain elevated concentrations of naturally occurring radioactive materials. This study assesses the natural radioactivity of soil samples collected from active and abandoned tin mining sites in Barkin Ladi, Shendam, and Jos East local government areas. Thirty soil samples are collected from mine tailings, drainage channels, and background reference sites and analysed using a high-purity germanium gamma-ray spectrometry system. Activity concentrations of Ra-226, Th-232, and K-40 are quantified, and the radiological hazard indices including radium equivalent activity, external hazard index, and annual effective dose are computed. Results indicate that mine tailings samples contain Ra-226 activity concentrations of 58 to 234 Bq per kilogram, significantly elevated relative to background soils (12 to 28 Bq per kilogram). Thorium-232 concentrations in tailings reach 180 Bq per kilogram, consistent with columbite mineral association. External hazard index values exceed 1.0 for 40 percent of tailings samples, indicating a radiological concern for miners and nearby residents. Keywords: radioactivity, tin mining, Plateau State, gamma spectrometry, radium equivalent