The amounts of Ni, Cr, Zn, Pb, Cu, Fe and Mn in some lichens growing in Switzerland

The amounts of Ni, Cr, Zn, Pb, Cu, Fe and Mn in seven lichens growing in Switzerland were determined. The lichen species were Hypogymnia physodes, Pseudevernia furfuracea, Cladonia rangiferina, Cetraria islandica, Parmelia sulcata, Usnea sp. and Letharia vulpina. By the use of intersite, interelement and interspecies comparisons, it is concluded that some metals within the thalli of Swiss lichens may reach high levels even when these plants are growing in rural and isolated sites. High amounts of Cr, Ni, Cu and Fe were detected in Pseudevernia furfuracea, growing far away from industrial plants and busy motorways. The same phenomena were observed in Parmelia sulcata. In general, Fe, Zn and Pb were found in higher amounts in lichens collected in Switzerland relative to other metals. The amounts of Pb in Swiss lichens were especially high in material collected close to busy roads and at tourist sites. P. sulcata demonstrated large differences in the Pb content of thalli collected at two different sites in the same city. A difference exists between the affinity of P. furfuracea and Hypogymnia physodes to accumulate Ni. There also exists a possible difference among P. sulcata, P. furfuracea and H. physodes to accumulate Mn. A coefficient of variation obtained for the measured metal in the studied lichen is suggested for uptake comparisons. This parameter is suggested for elucidation of whether a certain metal incorporated in the lichen thallus occurs in minute well-dispersed particles, as is assumed in the case of Zn, or in big particles. High coefficients of variation obtained for Cr, Ni and Cu in most of the studied lichens were attributable to big metal-containing particles entrapped in the lichen thallus.