Characteristic of an Oil Spill Site at Delta State, Nigeria

This study was aimed to evaluate the residual heavy metals concentrations, within the soil of a former petroleum spill site. Soil samples were spatially collected from five locations within a former petroleum spill site, located at Ozoro in Isoko North Local Government Area of Delta State, Nigeria. The concentrations of seven heavy metals (Ni, Cu, Zn, Pb, Cd, Fe and Al) in the soil (0–25 cm) were collected were determined, using the Atomic Absorption Spectrometer. In addition, soil contamination factor and Pollution Load Index were used to assess the heavy metals contamination and distribution within the study area. Results of the soil analysis revealed that the concentrations of the heavy metals were generally higher, when compared with results recorded from the Reference Point. Cadmium (Cd) concentration within the study area exceeded the maximum permissible limit, recommended by World Health Organization (WHO) for soils; while the others heavy metals concentration fall below the maximum permissible limit recommended by WHO for soil. The results revealed that spatial point 3, recorded the highest heavy metals concentrations across the study area. Generally, the contamination factor results showed that there is a considerable degree of residual heavy metals contamination in the cleaned up petroleum spill site. Likewise, the Pollution Load Index results showed that spatial points 2, 3 and 5 zones were highly polluted with heavy metals; while spatial points 1 and 4 zones were moderately polluted with heavy metals. This study exhibited the importance the oil companies to carry out remediation follow-up in petroleum spill area, to avoid accumulation of residual heavy metals in the environment.