Bioavailable Trace Elements in Soils around Nnpc Oil Depot Jos, Nigeria.

The concentrations of trace elements (Cu, Zn, Cr, Pb and Cd) in soil samples around NNPC Oil Depot Jos and those of a control area (about a kilometer away from the depot) were investigated by sequential extraction method using Atomic Absorption Spectrometer (AAS). Results obtained showed the concentrations (mg/kg) of Cu, Zn, Cr, Pb and Cd in soil of study area as 22.14, 25.06, 12.41, 14.13 and 9.11 respectively while in control area soil Cu, Zn, Cr, Pb and Cd had concentrations (mg/kg) of 19.69, 22.79, 7.09, 13.53 and 1.24 respectively. The bioavailable components (obtained from exchangeable, water and acid-soluble, and reducible phases) of Cu, Zn, Cr, Pb and Cd were 48.19%, 47.61%, 37.87%, 43.52% and 50.71% of their total concentrations respectively in study area soil while in control area 40.49%, 45.37%, 64.03%, 36.07% and 45.02% were obtained for Cu, Zn, Cr, Pb and Cd respectively. Levels of the trace elements in soils of both study area and control area were observed to be within European Union safe limits except for Cd in the study area. Keywords: Bioavailable fraction, Oil depot, Pollution, Sequential extraction, Trace elements.