Potentially toxic elements in facultative metallophytes Biscutella laevigata and Silene vulgaris along the stream descending from the abandoned Raibl mine (Italy)

The Raibl mine, located on the Italian side of the Julian Alps, was Italy's most productive lead (Pb) and zinc (Zn) mine until operations ceased in 1991. The large volume of by-products generated several environmental problems. Potentially toxic elements (PTEs) migrated along the Rio del Lago/Slizza streams contaminating the banks. The metal tolerance of the facultative metallophytes Biscutella laevigata and Silene vulgaris has been assessed using the bioconcentration factor and translocation factor. In aboveground tissues of B. laevigata were detected 0.05-1.92 mg kg-1 of Cd, 0.21-234 mg kg-1 of Pb, 0.49-1587 mg kg-1 of Tl and 20.6-3391 mg kg-1 of Zn, and of S. vulgaris 0.01-1.60 mg kg-1 of Cd, 0.01-138 mg kg-1 of Pb, 0.01-578 mg kg-1 of Tl and 14.9-1590 mg kg-1 of Zn. Concerning the phytoremediation potential, both species have confirmed promising characteristics, but S. vulgaris should be preferred to B. laevigata for phytostabilization projects in substrates with low Tl concentrations. The high concentrations of PTEs found in the sediments of the Rio del Lago/Slizza and in the herbaceous plants collected from the watercourse banks raise concerns about the potential impact of these elements on the surrounding ecosystem.