Das Projekt "Die Geochemie von Schwermetallen in Waldboeden der Schweiz: Quantifizierung atmosphaerischer, pedogener und lithogener Eintraege" wird vom Umweltbundesamt gefördert und von Universität Bern, Geologisches Institut durchgeführt. A multidisciplinary, collaborative investigation is underway to investigate the fundamental processes controlling the concentrations, chemical forms, and physical fluxes of heavy metals in Swiss forest soils. The principle objective of the study is to clearly distinguish between natural versus anthropogenic sources and chemical forms of potentionally toxic heavy metals. The rates of atmospheric metal deposition to the soils are determined independently using peat cores from bogs in the Cantons of Jura, Berne and Ticino. Analyses of these cores for heavy metals, stable and radioactive isotopes of Pb, and pollen are used to provide a long term record (past 5000 years) of atmospheric metal fluxes. Similarly, analyses of total metal concentrations and stable isotope ratios (Pb) of extracts of the dominant soil fractions (crystalline, Al/Fe oxide, exchangeable, and organically-bound pools) will allow us to identify the natural weathering pathways for metals in forest soils. Leading Questions: What are the natural background concentrations of heavy metals in the selected forest soils, and how do these compare with the concentrations due to anthropogenic activities? What are the natural weathering pathways of the metals of interest and to what extent are the anthropogenic metals mobilized? Using peat cores from ombrotrophic bogs, what are the present rates of atmospheric supply of heavy metals to the soils? Again using peat cores from bogs, how have these rates evolved with time (past several thousand years)?