An XAFS investigation of the artefacts caused by sequential extraction analyses of Pb-contaminated soils

The chemical processes that occur during sequential extraction of a highly Pb-contaminated soil sample were investigated using XAFS spectroscopy for t he identification of the Pb species in the solid residues after each step. The sequential extraction was performed following the procedure described b y Salomons and Forstner [1]. It was found that during the sequential extrac tion serious alteration of the chemical binding forms of the Ph occurs. The most important processes underlying the chemical changes are the re-adsorp tion of solubilized Pb ions by soil matrix components and the precipitation of insoluble Pb species with anions from the extractant.