Effect of Oil Spillage on Selected Heavy Metals Concentration in the Soils of Ihugbogo in Ahoada East, Niger-Delta, Nigeria

This study was carried out in Ihugbogo community, Ahoada East, Southern Nigeria- a community where Total E & P Nig. Ltd has carried out oil exploration and drilling dating back to over thirty years. This has led to a number of spillages on most arable soils in a community where peasant farming is a major occupation. Three locations were selected for the study, and designated as Location A, B and C which had experienced spillage in 1995, 2002 and 2007 respectively. Causes of spillage ranged from activity of vandals, leakage or explosion of the piping materials and or pressure from the crude oil products. This research however, sought to investigate the effects of the crude oil spillage on the selected heavy metals concentration of the soils as excess dosage of heavy metals on soils and invariably crops may lead to adverse health effect on man and animals which depend on crops for survival. The selected heavy metals studied were Chromium (Cr), Cadmium (Pb) and Lead (Pb). Results obtained indicated that Chromium and Lead were within the allowable limits (< 100 mg/kg) while Cd had value beyond the allowable limits (>3.0 mg/kg) according to World Health Organization. Physical and Chemical Properties of the studied soils indicated that the soils ranged from Sandy loam in locations A and B to Sandy in Location B. Available P was very low (<5.0 mg/kg) in locations A and B and moderate (5 – 15mg/kg) in location C while the exchangeable bases were very low as Ca was <2.0 cmol/kg, K and Na were <0.1 cmol/kg in locations A, B and C except Mg which was moderate (1.5 – 3 cmol/kg) in locations A and B and low (< 1.5 cmol/kg) in location C when the threshold limits were considered. There was a very strong and positive correlation between the heavy metals studied and soil organic carbon. For the studied soil to be very fit for agricultural productivity, liming will be necessary to reduce the soil acidity while organic and inorganic materials will be needed to enhance the nutrient element status of the soil.