Geoelectrical Assessment of Aquifer Vulnerability and Petroleum Contamination along the Kolo Creek Oil-Producing Corridor, Bayelsa State, Nigeria

Groundwater protection in petroleum-producing areas requires assessment of both subsurface characteristics and measured contaminant concentrations. This study assessed aquifer vulnerability and petroleum-related groundwater contamination along the Kolo Creek oil-producing corridor in Ogbia Local Government Area, Bayelsa State, Nigeria, using vertical electrical sounding (VES), groundwater physicochemical analysis and petroleum contaminant measurements. Five VES locations across Otuasega, Oruma, Imiringi, Elebele and Emeyal communities were investigated using the Schlumberger electrode configuration. Interpreted geoelectrical parameters included aquifer resistivity, aquifer thickness, overburden longitudinal conductance and transverse resistance. Groundwater samples were analysed for pH, electrical conductivity (EC), total dissolved solids (TDS), dissolved oxygen (DO), total petroleum hydrocarbons (TPH), benzene and total polycyclic aromatic hydrocarbons (PAHs). Aquifer resistivity ranged from 42 to 156 Ω m, while aquifer thickness varied from 8.4 to 15.4 m. Longitudinal conductance ranged from 0.181 to 0.402 S, indicating weak to moderate overburden protective capacity. Groundwater pH ranged from 5.4 to 6.5, EC from 165 to 460 µS/cm and TDS from 106 to 294 mg/L. TPH concentrations varied from 0.04 to 0.42 mg/L, benzene from 0.4 to 4.8 µg/L and total PAHs from 0.06 to 0.78 µg/L. Imiringi (VES 3) recorded the highest concentrations of the measured petroleum contaminants and was assigned the highest follow-up priority, whereas Elebele (VES 4) recorded the lowest contaminant concentrations. The findings identify spatial differences in aquifer properties, overburden protection and petroleum contamination across the study area.