Lichens as monitors of the atmospheric deposition of potentially toxic elements in high elevation Mediterranean ecosystems

In this study we used a terricolous lichen (Cetraria islandica) as bioaccumulator of potentially toxic elements (PTEs) to explore spatial patterns of air pollutant deposition along elevational gradients in the Majella Massif (Italy). Samples of C. islandica were collected at 200 m intervals along 6 transects from 1600 to 2600 m, both along the eastern and the western slope of the Majella massif, and analyzed for their PTE content. The results supported the hypothesis that the deposition of PTEs to the Majella massif is largely influenced by elevation and slope. Two main patterns emerged connected either with local soil erosion and long-range atmospheric transport. For some PTEs, namely Al, Cr, Li, Mg, in the absence of any other data, it is supposed that the anthropogenic input is very small compared to the natural input from weathering processes. In contrast, the group of air pollutants subjected to long-range transport, as in the case of Cd, Hg, and Pb, has very limited local input and the main sources responsible for the higher concentrations on the eastern slope are probably to be searched in the Balkan area.