Heavy Metal Pollution Assessment of Granite Quarrying Operations at Ikole-Ekiti, Nigeria

Abstract

The impact of previous operations on the environment was assessed by determining heavy metal contents of soil (topsoil, 0-15 cm and subsoil,15-30 cm) and plant samples taken at 0, 10, 15, 30, 60, 120 and 200 m from an abandoned granite quarry and compared to samples from a control (baseline) location. Fe was the most abundant element in the topsoil (0-15 cm) and subsoil (15-30cm), Cd was below detectable level while other elements were present in the order: Mn>Cr>Pb>Ni>Cu>Co. Fe, Pb, Cu, Cr and Ni were highest at 0 m and decreased with distance from the quarry site. The metals showed deficiency to moderate enrichment and low to moderate contamination at some distances but more in the topsoil than in the subsoil such that the Pollution Load Index (PLI) was <1.0 at all points in the topsoil. Fe and Mn were most abundant in all the plants and Aspilia africana contained the highest Pb and Co while Ni was highest in Synedrella nodiflora and Chromolaena odorata. The Transfer Factor, Shoot: Root Quotient and Extraction Coefficient exceeded 1.00 for most of the heavy metals especially at 0 and 10 m. The potential of Chromolaena odorata for Fe accumulation was indicated just as Sida scabrida would be an excluder of Cu.