Environmental Assessment of Hydrocarbon Impacted Site at Ajeokpori Oil Spill Site Using Electrical Resistivity Tomography Technique

This study investigates the environmental assessment of Ajeokpori of an oily-impacted site using electrical resistivity tomography. A fusion of field-based measurements with advanced geochemical method was used to delineate the precise depth and boundaries of the affected zones. This study characterizes crude oil-impacted sites using Electrical Resistivity Tomography (ERT) at depths of 1.0, 3.0, 6.0, 9.0, and 12.0 meters. An inverse resistivity model was employed to analysed contamination zones based on resistivity values. The colour gradient in the resistivity profile ranged from dark blue and green (low resistivity) to brown, orange, and red (high resistivity), indicating variations in subsurface material properties. Low-resistivity zones, extending from 1.0m to approximately 10.5m depth, suggested the presence of clay or water-saturated materials. Analysis along a 150.0m survey line in the NE-SW direction revealed three contamination plumes. The first and third plumes extended laterally between 0m–100.0m and 155.0m–162.0m, with depths from 0m to 6.0m. The second plume, spanning 106.0m–144.0m laterally, extended beyond the maximum investigation depth of the Res2Dinv model. The depth of oil contamination was from 4m that sometimes varies from different location and the plume direction that predominantly spread beyond the maximum investigation depth of 11 .8m for both Res2Dinv and earth imager model. The Earth Imager model corroborated these findings, showing scattered low-resistivity zones, likely representing localized high-moisture or clayey deposits within higher-resistivity surrounding material. These results provide critical insights for contamination assessment and remediation planning.