Effect of Crude Oil Contamination and Bioremediation with Fertilizer on Physicochemical Properties of Soil

The release of hydrocarbons into the environment whether accidentally or through human activities is a main cause of water and soil pollution. This study investigated the effect of crude oil contamination and fertilizer treatment on soil physicochemical properties. Unpolluted soil samples obtained from the bed of Ovia River, Benin City, Nigeria, were contaminated with crude oil, and thereafter remediated with NPK/urea fertilizer. A range of physicochemical parameters were measured in both soil samples. The results showed that electrical conductivity, moisture content, water holding capacity, total nitrogen content and available phosphorus were significantly higher in contaminated clay soil than in sandy-clay soil, while bulk density, porosity and pH were higher in contaminated sandy-clay soil than in clay soil (p < 0.05). After 36 days bioremediation of the contaminated clay/sandy-clay soils with NPK/urea fertilizers, the results followed the same trend. Crude oil-contamination and fertilizer treatment significantly and concentration-dependently increased organic matter of both soils but it did not significantly alter total petroleum hydrocarbon (TPH) content. In addition, crude oil-contamination of clay/sandy-clay soil markedly increased the TPH, but it was significantly and concentration-dependently reduced by fertilizer treatment. These results indicate that bioremediation strategy that employs fertilizer may be useful for restoring soil fertility after an episode of crude oil contamination. Keywords: