Mercury accumulation and biotransportation in wetland biota affected by gold mining

Abstract

Phytoremediation is a cost-effective, eco-friendly technology for the removal of metals from polluted areas. In this study, six different plant species (Datura stramonium, Phragmites australis, Persicaria lapathifolia, Melilotus alba, Panicum coloratum, and Cyperus eragrostis) growing in a gold mine contaminated wetland were investigated as potential phytoremediators of mercury. The accumulation of total mercury and methylmercury in plant tissues was determined during the wet and dry seasons to establish the plants' variability in accumulation. The highest accumulation of total mercury was in the tissues of Phragmites australis with recorded concentrations of 806, 495, and 833μgkg-1 in the roots, stem, and leaves, respectively, during the dry season. The lowest accumulation levels were recorded for Melilotus alba during both seasons. The highest amount of the methylmercury was found in Phragmites australis during the dry season with a value of 618μgkg-1. The accumulation and biotransportation were not significantly different between the seasons for some plants. The results of this study indicated that plants growing in wetlands can be used for phytoremediation of mercury and suggest the choice of species for constructed wetlands.