A record of anthropogenic Pb deposition in a Mediterranean karst catchment (Lake Vrana, Cres Island, Croatia)

摘要

To trace the history of anthropogenic, atmospheric Pb pollution, analyses of soils from the region and of cores from the karst Lake Vrana (Croat: Vransko jezero) on the island of Cres were performed. The area affected by Pb pollution in Croatia covers most of the high-mountain karst region. Since lake sediments can act as archives of atmospheric deposition of metals (and other pollutants) a multielement analysis as well as Pb isotopes of dated sediment core samples and palaeosoil from the catchment enabled the evaluation of Pb-pollution history. The Pb/Sc ratios and the ~(206)Pb/~(207)Pb ratios allowed the calculation of enrichment factors and the anthropogenic contributions of Pb during the past 4000 y. The sediments of Lake Vrana were found to be a consistent record of Pb pollution in this part of the Mediterranean region, despite the fact that the catchment lost most of its soil cover between 1404 and 1650 AD due to deforestation which caused a major change in sediment composition.