Heavy metal enrichment and potential ecological risks from different solid mine wastes at a mine site in Ghana

Abstract

Solid mine wastes characterization is important for understanding their chemical composition, as well as potential ecological and health risks, although limited empirical data exist on this, particularly in developing countries. In this field study, quantitative contamination indices like geoaccumulation index, enrichment factor, contamination factor, Hazard quotient and ecological risk were used to characterize and compare solid mine wastes from three different sites (i.e., sulphide waste dump, oxide waste dump and mine tailings) and soil from a farmland (reference site). Fifteen plots (each measuring 20 m × 100 m) were randomly demarcated on each of the study sites. A composite sample was obtained from each plot and analyzed for heavy metals (Fe, Cu, Cd, As, Pb), following which the various contamination parameters were determined. Results showed high enrichment of the solid mine wastes with the studied heavy metals compared to the local background values, with non-essential metals (As, Cd, Pb) displaying higher accumulation potential than the essential metals (Fe, Cu). The heavy metal enrichment of the three waste types were high enough to exert significant health risks (HQ>1) and ecological risk (IER>600) compared to the reference site (HQ<1, IER<150). However, the magnitude of the health and ecological effects varied with waste type in the order: oxides<sulphides<tailings. These results highlight the need for proper solid mine wastes characterization to drive management decisions aimed at reducing heavy metal contamination of surrounding soils and the associated potential environmental and human health risks.