GEOCHEMICAL ASSESSMENT OF SOIL USED FOR FARMING FROM AN ABANDONED MINING SITE IN JOS-SOUTH L.G.A., USING ATOMIC ABSORPTION SPECTROSCOPY (AAS) TECHNIQUES

Abstract

This study was undertaken to assay the geochemical assessment of soil used for farming from an abandoned mining site in Jos-South L.G.A., using Atomic Absorption Spectroscopy (AAS) techniques, Plateau state, Nigeria. A modified sequential extraction procedure of Tessier et. al., (17) was used in separating the total metal concentrations into four operationally defined fractions (exchangeable and carbonate, Fe and Mn oxides, organic matter, and residual fractions).Where it was discovered that the bulk of metals were partitioned to the residual fraction (Zn- 138.85ppm, Pb-55.59ppm and Cd-2.5ppm) which implies that the soils of the farmland are not polluted by any of the metals studied. Pollution indices also as compared with Banat et. al., (3) standards, indicated minimal contamination of the soils matrix with Cd, which had enrichment factor value of 15.4 and I-geo factor of 4. The bulk partitioning of the metals onto the residual fraction indicates a lithogenic origin of the heavy metals, i.e. the heavy metals were directly inherited from the parent material, and also a low risk of contaminant transfer under normal cultural practices. However, It is recommended that soil sample collections should be done in such a way that mobility index can be calculated, because it is a more reliable indicator which considers the weakly adsorbed fractions alone, after a sequential extraction has been done.