Soluble/insoluble (dilute-HCl-extractable) fractionation of Cd, Pb and Cu in Antarctic snow and its relationship with metal fractionations in the aerosol

Department of Life and Environmental Sciences, Università Politecnica delle Marche, Ancona 60131, ITALY

^a a.annibaldi@univpm.it

Abstract

A chemical fractionation methodology for determination of the (water) soluble and the insoluble (dilute-HCl-extractable) fractions of Cd, Pb and Cu in Antarctic snow was set-up and verified for the additivity of the two fractions detected. Molten samples were filtrated and the water-insoluble fraction was extracted by dilute ultrapure HCl (pH ~1.5). Metal determinations were carried out in the two fractions by square wave anodic stripping voltammetry. The total metal concentrations in samples collected in the 2000–2001 austral summer in a clean area (Faraglione Camp) in the neighbourhood of the Mario Zucchelli Italian Station were of the order of Cd 10-20 pg g⁻¹, Pb 20–40 pg g⁻¹, Cu 60–120 pg g⁻¹ with an approximate equidistribution between soluble and insoluble fractions. These fractionations compare well (and show a quite consistent temporal trend) with those observed in the aerosol samples collected in the same area/period and confirm the close relationship between metal distributions in snow/ice and in the aerosol. At the station metal concentrations increase due to anthropic contribution and the distribution changes with Cd predominantly present in the soluble fraction (~80%), while Pb and Cu are more concentrated in the insoluble fraction, 70–80% and ~70%, respectively.