Mercury bioaccumulation and phytotoxicity in two wild plant species of Almadén area.

Mercury is a widely distributed environmental pollutant, able to induce toxicity in living organisms, including higher plants. Some plant species are able to grow in mine sites, like the Almadén zone in Spain. Our study focus on two of these plant species, Rumex induratus and Marrubium vulgare and their responses to natural Hg exposure. Total Hg concentration in the soil below the plants could be classified as toxic, although the available fraction was low. Hg availability was higher for the M. vulgare than for the R. induratus plot. Hg concentrations in field plants of R. induratus and M. vulgare grown on these soils can be considered as phytotoxic, although no symptoms of Hg toxicity were observed in any of them. According to the BAF (Hg/Hg), R. induratus showed a higher ability in Hg uptake and translocation to shoots, as well as higher concentrations of MDA and -SH:Hg ratios, so that this plant is more sensitive to Hg than M. vulgare. The resistance to Hg and the capability to extract Hg from the soil make both M. vulgare and R. induratus good candidates for Hg phytoremediation of contaminated soils.