Environmental Monitoring of Igbogila Lithology, North-Western, Ogun State using Radiometric Method

Abstract

This study investigates the environmental radiological implications and mineralogical signatures of the Igbogila lithology using ground radiometric data. The analysis focused on uranium (U), thorium (Th) and potassium (K) concentrations, their ratios (U/Th, U/K, Th/K), uranium migration index (UMI), and effective dose rate. The objectives were to assess uranium mobility, identify potential geochemical processes, and evaluate radiation exposure risks. The UMI spectra highlight spatial variability in uranium retention and leaching, with positive values indicating localized uranium enrichment and negative values reflecting strong leaching and thorium dominance. Notably, location A7 recorded the most negative UMI (≈ –14), which corresponded to the highest effective dose rate (> 2.0 mSv yr⁻¹), thereby suggesting thorium-controlled radiation hazards. In contrast, uranium-enriched zones exhibited relatively moderate dose rates (< 1.0 mSv yr⁻¹), implying that geochemical mobility of uranium does not always equate to elevated radiation exposure. The overall dose rates across the study area remained within international safety thresholds, though localized anomalies highlight potential environmental and health concerns. These results demonstrate that integrating UMI with dose-rate evaluation provides a robust approach to environmental monitoring and mineralogical assessment. The findings emphasize the dual need for groundwater monitoring in uranium-mobilized zones and radiation hazard management in thorium-rich terrains of the Igbogila area.