TRACE METAL PROFILE OF MORINGA OLEIFERA (LINN.) SEEDLINGS SOWN IN SPENT LUBRICATING OIL CONTAMINATED SOILS

Trace metal profile of Moringa oleifera seedlings grown in spent lubricating oil contaminated soil was evaluated in Asaba, Delta State, Nigeria during the 2012 growing season. Oil concentrations used were 0.00, 1.37, 2.77, 4.15 and 6.92% (w/w). The results showed that spent lubricating oil in soil significantly (P≤0.05) increased trace metals in soil and Maringa oleifera plant tissues relative to the control. Trace metal identified included Pb, Fe, Zn and Cu and their values were significantly (P≤0.05) higher when compared with values obtained from the uncontaminated soils. The results also showed that the amount of trace metals accumulated is dose-dependant as the values obtained in higher concentrations of oil application were significantly (P ≤0.05) higher than values recorded in the control subplots. This study has demonstrated that spent lubricating oil leads to gradual accumulation of trace metals in soils and plant tissues which could have health risk in the Nigeria rural environment especially in the Niger Delta where oil activities are predominant.