Levels of heavy metals and contamination status of a decommissioned tailings dam in Ghana

Abstract

Heavy metal pollution from tailings has become a major global concern due to its toxicity, persistence and accumulative potential with its detrimental effects on public health and environmental receptors. In a bid to determine the contamination status of a decommissioned Tailings Storage Facility (TSF 2) from Chirano Gold Mine limited (CGML), scoop of mine tailings were collected down to a depth of 20 cm from nine sampling sites within a 8100 m2 grid. Concentrations of As (0.7 to 3.3), Pb (1.3 to 2.2), Cr (0.9 to 1.9), Cd (2.0 to 2.6), Cu (5.5 to 6.5), Zn (2.4 to 3.6) and Fe (4.5 to 12) mg/kg were below FAO/WHO permissible limits. Concentration of heavy metals statistically varied between sampling sites (p < 0.05). The geoaccumulation index and contamination factor revealed that, TSF 2 is uncontaminated with As, Pb, Cr, Cu, Zn and Fe. However, mine tailings were significantly enriched with Cd, and thus likely to pose ecological risk to the surrounding environment. In general, the tailings dam is not progressively deteriorating in accordance to pollution load index. Findings of this study would contribute to the environmental database of gold mine tailings at CGML to assist future remediation of the Tailings Storage Facility.