Analysis of Heavy Metals in Soils of Enyigba and Abakaliki Using Proton Induced X-Ray Emission (Pixe) Spectroscopy

Abstract

Composite soil samples were collected about 200 m2 apart at 0-30 cm (top soil) and 60-90 cm (subsoil) depths from Enyigba Pb-Zn Mine and Abakaliki Urban during the dry season in December, 2010. The soils were analyzed for pH and total contents of As, Cd, Co, Cu, Fe, Mn, Ni, Pb and Zn using Proton Induced X-Ray Emission (PIXE) Technique. Results show that total mean concentrations of the heavy metals decreased with depth. Whereas the mean concentrations of the metals in the top and sub soil of Enyigba Mine decreased respectively in the order, Fe > Pb > Zn > Cu > Mn > Cd > Co > Ni > As and Fe > Zn > Cu > Mn > Pb > Co/Ni > Cd > As in the subsoil, the top and subsoil of Abakaliki Urban showed similar trend in the order, Fe > Mn > Pb > Zn > Co/Cu > Ni > Cd > As. The total mean concentrations of the metals in the top and sub soils of Enyigba Mine were found to be higher than those of Abakaliki Urban. Elevated concentrations of Pb > Ni > Cd above the US-EPA Regulatory Limits in that order was observed only in the Enyigba Mine top soil, while variations in the heavy metal levels were generally observed between and within groups. The mean soil pH obtained in Enyigba Mine and Abakaliki Urban was 6.5 and 6.8 respectively.