Natural Radioelement Concentrations and Dose Rate Assessment Using High-Resolution Aeroradiometric Data of Dapchi and Biriri Areas, Upper Benue Trough, Nigeria

This study investigates the distribution of natural radioelements and the associated radiation exposure levels in the Dapchi and Biriri areas of the Upper Benue Trough, Nigeria, using high-resolution aeroradiometric data obtained from the Nigerian Geological Survey Agency (NGSA). The radiometric dataset was processed and interpreted using Oasis Montaj 8.4 and Surfer 14 to evaluate the concentrations of uranium (U), thorium (Th), and potassium (K), alongside their corresponding dose rates. The results reveal that uranium concentrations range from 1.56 to 2.90 ppm, thorium from 7.8 to 11.9 ppm, and potassium from 0.50 to 0.83%. Spatial analysis shows that the southwestern part of Dapchi exhibits the highest radioelement concentrations, a pattern attributed to the dominance of granitic and metamorphic formations enriched in radiogenic minerals. The computed dose rates vary between 0.402 and 0.472 mSv/year, with an average value of 0.439 mSv/year. Areas with elevated dose rates coincide with regions of high U, Th, and K concentrations, while lower values occur mainly in Biriri, corresponding to sedimentary lithologies such as sandstone and shale. Despite observable spatial variations, all recorded dose rate values remain below the globally recommended natural background radiation limit of 1.0 mSv/year. This indicates that the natural radiological environment within the study area presents minimal health risk to the local population and provides important baseline data for environmental monitoring and geoscientific studies.