Optimization of a sequential extraction scheme for the characterization ofheavy metal mobility in iron oxide rich sediments

Several parameters governing the extraction of metals from iron oxide rich sediments, using sequential extraction schemes were optimized. The mode of shaking, soil/extractant ratio and concentrations of MgCl2 and NH2OH . HCl, fur samples collected in the Odiel Marshes Natural Park (SW Spain), were c onsidered. The concentration of NH2OH . HCl deserved particular attention d ue to the nature of the studied sediments. A 0.4 M concentration of this ex tractant was needed to avoid readsorption of Cu and As in the samples. In a ddition, readsorption processes were studied using a candidate to reference material with a high organic matter content that was previously analyzed i n an interlaboratory study.