Soil contribution to the elemental composition of epiphytic lichens (Tuscany, central Italy)

Total concentrations of Al, Ba, Cd, Co, Cr, Cu, Fe, Mn, Mo, Pb, Sr, Ti, V a nd Zn in the epiphytic lichen Parmelia sulcata and superficial soils from 6 0 remote sampling sites in Tuscany (central Italy) were determined to evalu ate the contribution of soil to the elemental composition of the lichen. Th e results showed that in the Mediterranean environment, the trace element c ontent of unwashed lichen samples is greatly affected by soil contamination . However, despite the strong correlations between the concentrations of li thogene elements such as Al, Fe and Ti in P. sulcata, lichen levels of thes e elements were not at all linearly correlated with their concentrations in the soil, suggesting that dust contamination is highly variable and probab ly dependent on local site characteristics. All methods evaluated to minimi ze soil contamination indicated Cu, Pb and Zn as elements of atmospheric or igin. However, while levels of Pb were similar to those reported for backgr ound areas, moderate pollution by Cu and Zn, probably from fertilizers used in agriculture, was revealed. For elements such as Cd and Mo, identified a s atmophile, some uncertainty exists due to the fact that they are essentia l for lichen metabolism and accumulate intracellularly in lichens; they may therefore occur in soluble form in the lichen thallus.