Application of 2-D Electrical Resistivity Tomography and Radiometric Techniques in Assessing Groundwater Vulnerability and Soil Contamination in Jos Mining Area, Nigeria

Abstract

Groundwater resources within mining environments are increasingly threatened by contaminant infiltration and radionuclide migration resulting from intensive mineral exploitation. This study integrates Vertical Electrical Sounding (VES), Two-Dimensional Electrical Resistivity Tomography (ERT), and radiometric techniques to assess groundwater vulnerability and soil contamination in the Rayfield mining area of Jos Plateau, North-Central Nigeria. Geoelectrical investigations were conducted to delineate subsurface lithology, identify aquifer units, and evaluate groundwater vulnerability, while radiometric analyses were performed to determine the distribution and potential hazards of naturally occurring radionuclides. The VES results revealed a seven-layer geoelectric succession characterized by an HQ-type curve, with resistivity values ranging from 20.5 to 509 Ωm. A thick fractured basement aquifer with a resistivity of 271 Ωm and thickness of approximately 36.2 m constitutes the principal groundwater reservoir. ERT imaging delineated three distinct subsurface zones comprising a conductive contaminated zone, saturated weathered materials, and consolidated lateritic-basement formations. A prominent low-resistivity anomaly (<36.5 Ωm) was interpreted as a contaminant plume associated with mining-derived leachates and radionuclide-enriched pore fluids, indicating active contaminant migration through weathered and fractured pathways. Radiometric assessment showed mean values of 88.91 Bq kg⁻¹, 279.4 μSv y⁻¹, 0.24, 0.33, and 0.17 × 10⁻³ for Raeq, AGED, Hex, Hin, and ELCR, respectively, all below internationally recommended limits. However, localized radionuclide enrichment was observed at specific lithological horizons. The integrated interpretation indicates moderate to high groundwater vulnerability despite favourable groundwater potential. The study demonstrates that combining geoelectrical and radiometric methods provides an effective framework for identifying contaminant migration pathways, evaluating environmental risks,...