Alterations in Physicochemical Properties of Soils Impacted by Ahoada Oil Spill in Rivers State, Nigeria

Oil spills remain a critical environmental threat in the Niger Delta region of Nigeria, particularly in Edeoha, Ahoada East, Rivers State. This study evaluated the physicochemical alterations in oil-contaminated soils. Ten composite soil samples were collected from depths of 0–15 cm and 15–30 cm across affected sites. Key parameters measured included pH, electrical conductivity (EC), total organic carbon (TOC), total organic matter (TOM), total nitrogen (TON), phosphorus, potassium, chloride, nitrate, carbonate, sulfate and phosphate. Results showed pH values ranged from 5.67 to 6.10, falling below the EGASPIN-recommended 6–9 range. EC levels (75–106 µS/cm) indicated altered ion content. TOC values (1.53%–3.99%) exceeded the 3% USEPA threshold for non-agricultural soils. TON (0.088%–0.166%) was within natural soil ranges, while phosphorus (0.19–0.36 mg/kg) and potassium (16.45–34.30 mg/kg) were below agronomic thresholds. Chloride levels (14.2–19.2 mg/kg) approached the USEPA advisory limit of 20 mg/kg. Nitrate (2.25–2.67 mg/kg) slightly exceeded typical background values, whereas carbonate (2.30–3.40 mg/kg) and sulfate (1.23–2.31 mg/kg) remained within acceptable ranges. These findings highlight extensive alterations in soil chemistry and pollutant concentrations that exceed national and international safety standards, indicating an urgent need for targeted soil remediation and long-term environmental monitoring in the region.