Elemental composition of Marrubium astracanicum Jacq. growing in tungsten-contaminated sites

Abstract

This study evaluates the elemental (W, Mo, Zn, Fe, Cu, Cd, Mn, Pb, Cr, Co, B, and Bi) composition of Marrubium astracanicum Jacq. (Lamiaceae), around the abandoned tungsten mine on Uludag Mountain, Turkey, to determine if it is an appropriate candidate for phytomonitoring and/or phytoremediation purposes. Three sample sites were selected around the mine for soil and plant sampling. Two sites approximately 500 m from the mine were assumed to be unpolluted sites. The other site was selected from a waste removal pool (WRP) and was assumed to be a polluted site. The soil and different organs (roots, leaves, and flowers) of plant samples were analyzed by inductively coupled plasma-mass spectrometry (ICP-MS) to determine the elemental content. The classic open wet digestion procedure was applied to the samples with 5 mL HNO3 and 3 mL H2O2 in a borosilicate glass vessel for the roots, leaves, and the flowers of the plants. Kjeldahl digestion was used for the soil samples. The W, Zn, Fe, Cu, Cd, Mn, Pb, B, and Bi contents were found to be higher in the soil samples from the waste removal pools compared with the samples from the unpolluted sites. We also found that the elemental composition of M. astracanicum has generally been increased by the activity of the tungsten mine, and there were significant correlations between the elemental contents of the soil samples and plant parts, except for Mo and Cr. The high level of many elements in the soil samples indicates the presence of contamination related to tungsten-mining activity on Uludag Mountain. Assessing the elemental contents of M. astracanicum, we can suggest this species as a candidate for phytoremediation purposes of W-contaminated sites due to its high W-accumulation capacity.