文摘
A total of 25 lichen thalli of Parmelia conspersa (Ehrh),collected at Vulcano island and at Mt. Etna, during a one-year biogeochemical survey, were analyzed for Pb, Br,Al, Sc, 206Pb/207Pb, and 208Pb/206Pb ratios. Lead isotope ratioswere also measured on aerosols samples from urbanareas and industrial sites of Sicily. The observed 206Pb/207Pb range for urban and industrial aerosols (1.103-1.174)closely matches the anthropogenic signature (1.080-1.165). Lichens (206Pb/207Pb = 1.156-1.226), instead, arecloser to the compositional field of 206Pb rich geogenicsources. This natural input is more evident at Vulcano islandthan at Mt. Etna, where the anthropogenic activities areconsiderably more effective. On the basis of lead isotopedata, Pb/Br ratios and calculated lead enrichmentfactors, a "natural" lead pollution from volcanoes issuggested. Volcanic lead contribution ranges from 10 to30% at Mt. Etna to 10-80% at Vulcano island.