Partitioning of heavy metals in different particle-size fractions of soils from former mining and smelting locations in Austria

Abstract

Austrian soils from mainly historical mining and smelting sites were separated into four particle size fractions (coarse sand, fine sand, silt and clay) to distinguish the possible origins and pathways of heavy metals. Each fraction was extracted with aqua regia to determine the pseudo-total content and with CaCl2 to determine the available content of metals. The soil mineralogical composition of the < 2000 µm fraction was determined by X-ray diffraction (XRD). In general, the concentration of heavy metals and metalloids increased as soil particle size decreased. Based on the correlations of concentrations vs. the log of the mean particle size, obtained from each fraction the presence of unweathered allochthonous minerals were especially present in samples from locations at Rabenstein for most trace elements, at Arzwaldgraben for Cd, Co, Mn and Pb, at Johnsbach for Cd, Co, Mn, Pb and Zn and at Pilgersdorf for Cr. The opposite trend was found for the samples of the industrial area of Arnoldstein, Zeltweg and Hinterlobming suggesting that their metal load was derived from the discharge of effluents or from weathered phases.