Biogeochemical investigation of the Mt. Gunson minesite and surrounding semi-arid environment

Abstract

Near surface mobility and fixation of metals and their effects on plant growth were evaluated at the Mt Gunson tailing dam. The driving force for base metal distribution in the upper metre of the tailings is evaporation and capillary migration. Oxidation and break down of sulphides result in mobilisation of bivalent metals which are concentrated in the upper 40cm of the tailings (having metal concentrations up to four times greater than below 40 cm). Base metals (Cu, Zn, Co and Pb) become mobilised at low pH, resulting in high element concentrations available to plants. Plant experiments on the tailings material showed that the high level of dissolved metals, high salinity and low pH are toxic to all species. Sampling of the adjacent Gunyah Lake and Pernatty Lagoon salt lakes showed that elevated metal concentrations in particular Cu and Pb could be traced within Gunyah Lake but were at background levels beyond 630m from the bund wall of the Mt. Gunson tailings site.