Assessment of Soil Contamination by Crude Oil Spillage in Bayelsa State, South South Nigeria

This study assesses soil contamination from crude oil spillage in communities affected by petroleum pipeline leaks and wellhead spills in Bayelsa State, located in Nigeria's South South geopolitical zone. Crude oil contamination of farmland and forest soils in Bayelsa State represents one of the most severe environmental threats in Nigeria's oil-producing region, causing loss of agricultural productivity, water contamination, and community health impacts. Using a comparative field design, surface and subsurface soil samples were collected from three recently spilled sites, three previously spilled but partially remediated sites, and three uncontaminated control sites in Ogbia, Nembe, and Ekeremor local government areas. Samples were analysed for total petroleum hydrocarbons (TPH) by gravimetric extraction, polycyclic aromatic hydrocarbons (PAH) by GC-MS, soil pH, organic carbon, nitrogen, and total microbial counts. Findings revealed TPH concentrations in recently spilled soils averaging 48,000 mg/kg, far exceeding the 5,000 mg/kg Department of Petroleum Resources remediation target. PAH concentrations included carcinogenic compounds (benzo-a-pyrene, chrysene) at levels above international environmental quality guidelines. Soil pH was reduced to 4.3 in the most contaminated sites, and microbial counts were suppressed to below detectable levels in recently spilled plots. Partially remediated plots showed persistent TPH above target levels, indicating inadequacy of remediation approaches applied. The study recommends bioremediation using hydrocarbon-degrading bacteria combined with landfarming as an appropriate remediation strategy for Bayelsa State petroleum-contaminated soils. Keywords: crude oil spillage, soil contamination, Bayelsa State, petroleum hydrocarbons, bioremediation.