Mercury accumulation and biotransportation in wetland biota affected by gold mining Odwa Mbanga & Somandla Ncube & Hlanganani Tutu & Luke Chimuka & Ewa Cukrowska Received: 19 September 2018 /Accepted: 15 February 2019 # Springer Nature Switzerland AG 2019 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 contami- nated wetland were investigated as potential phytoremediators of mercury. The accumulation of total mercury and methylmercury in plant tissues was deter- mined during the wet and dry seasons to establish the plants’ variability in accumulation. The highest accu- mulation of total mercury was in the tissues of Phrag- mites australis with recorded concentrations of 806, 495, and 833 μg kg -1 in the roots, stem, and leaves, respectively, during the dry season. The lowest accumu- lation 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 618 μg kg -1 . The accumulation and biotransportation were not significantly different be- tween 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. Keywords Bioaccumulation . Mercury . Methylation . Phytoremediation . Seasonality . Wetlands Introduction Mercury (Hg) is a trace metal that occurs naturally in the earth’s surface. However, human activities have resulted in an enormous increase in the amount of its emission into the environment (Chen et al. 2016; De Simone et al. 2016; Song et al. 2015; Zhang et al. 2015). The major sources of Hg that add to its elevated levels in the atmosphere have been identified to be coal combustion from power plants and gold mining (Dabrowski et al. 2008; Pacyna et al. 2006; Pirrone et al. 2010). In South Africa, mining occurs in a region known as the Witwa- tersrand Basin. Due to intensive mining operations (Forstner and Wittman 1976), the number of tailing dams has grown to approximately 240 (Tutu et al. 2005). Environmental pollution due to tailing storage facilities does not only negatively impact the ground, but also extends to air pollution, sediments, streams, rivers, and dams (Fashola et al. 2016; Li et al. 2014; Odumo et al. 2014; Schonfeld et al. 2014). Elevated mercury pollution in the region is due to presently reprocessed old tailing dams dating back to when mercury amalgamation meth- od was used for gold extraction enlarged by intensive artisanal mining (Lusilao-Makiese et al. 2016). There are several methods used for the remediation of mine tailings. These include chemical stabilization, capping, and excavation (Akcil et al. 2015; Mukherjee 2014; Edraki et al. 2014; Mendez and Maier 2008; Environ Monit Assess (2019) 191:186 https://doi.org/10.1007/s10661-019-7329-z O. Mbanga : S. Ncube : H. Tutu : L. Chimuka : E. Cukrowska (*) Molecular Sciences Institute, School of Chemistry, University of the Witwatersrand, Private Bag X3, Johannesburg 2050, South Africa e-mail: ewa.cukrowska@wits.ac.za