We describe here in detail the results and the setup of the high precision Pb isotope ratio analysis performed by Multi Collector Inductively Coupled Plasma Mass Spectrometer (MC ICP MS), Thermo Scientific Neptune Plus TM. We performed this method adding thallium (Tl) as an internal isotopic standard to correct mass dependent isotopic fractionation. We also report the procedures for the chemical separat ion and purification of Pb from geological matri ces such as silicates , sulfides and historical artefacts . We report the data obtained on the international certified standard material SRM NIST 981 measured with MC ICP MS Neptune Plus, focusing on the accuracy and reproducibility of the analyses performed in the Neptune TIMS Laboratory (IGG-CNR in Pisa, Italy), and highlighting the advantages brought by the installation of this new mass spectrometer.
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)?