POST-REMEDIATION ENVIRONMENTAL MONITORING OF SURFACE WATER AND SEDIMENTS AT OLERO JACKET 43, NIGER DELTA, NIGERIA

Post-remediation environmental monitoring is essential for verifying whether clean-up objectives have been achieved following oil spill response activities. This study assessed surface water and bottom sediment quality at Olero Jacket 43, Delta, Nigeria, after remediation, using a compliance-based monitoring approach. Surface water and sediment samples were analysed for physicochemical parameters, petroleum hydrocarbons, and selected heavy metals. Results were summarised using descriptive statistics and compared with applicable regulatory guidelines. Surface water parameters, including total petroleum hydrocarbons and total hydrocarbon content, were within regulatory limits, indicating minimal residual contamination. Sediments showed acidic and organic-rich conditions typical of swamp environments, while hydrocarbon concentrations remained below regulatory target and intervention values. Heavy metal concentrations were generally low, with only minor cadmium enrichment observed below intervention thresholds. Overall, the results confirm that remediation objectives were achieved at the time of monitoring and highlight the importance of structured post-remediation monitoring for environmental management and regulatory assurance.