XAFS determination of the chemical form of lead in smelter-contaminated soils and mine tailings; importance of adsorption processes

Characterization and speciation of mercury-bearing mine wastes using X-ray absorption spectroscopy

“…phases. Ostergren et al 1999 determined from fitting the EXAFS spectra of mixtures of leadcontaining phases that fit components should be considered accurate to "25% of their stated value, and that fit components comprising less than 10% of a fit should be viewed with caution. This is consistent with the mixed model results presented here for Hg-containing phases and should apply similarly to the calcine speciation analyses.…”

“…Synchrotron radiation-based XAS has been shown to provide direct, in situ information on heavy metal speciation, and has been used successfully for such elements as arsenic, lead, and Ž zinc Cotter-Howells et al, 1994;Manceau et al, 1996;Hesterberg et al, 1997;Foster et al, 1998;. Morin et al, 1999;Ostergren et al, 1999 .…”

“…Morin et al, 1999;Ostergren et al, 1999 . The technique possesses the additional benefits of being non-destructive, element-specific, relatively sensitive at low concentrations, and requiring minimal sample preparation, thus allowing the analysis of samples in conditions similar to those observed in their natural state.…”

Geological and anthropogenic factors influencing mercury speciation in mine wastes: an EXAFS spectroscopy study

“…The EXAFS-based speciation procedure for Hg is similar to that previously developed for and applied to other metal(loid)s such as arsenic (1,2) , lead (3)(4)(5) , and zinc (6,7) . It involves the comparison of an EXAFS spectrum collected from a Hg-bearing sample with a spectral library of model compounds previously generated from an assortment of Hg minerals and sorbed species (Figure 3).…”

Fractionation of lead in soil by isotopic dilution and sequential extraction

“…[1,2,3] Sequential extraction of soils have shown that Pb is often associated with Fe and Mn oxide minerals and organic / sulphide fractions. [4,5,6] For example, Strawn et al, [7] showed that Pb was associated with Mn oxides and poorly crystallised Fe oxides, using electron microprobe and X-ray diffraction analyses of contaminated wetland soils. However, Lang & Kaupenjohann [8] suggested that Pb phosphates, especially pyromorphites, are the most stable Pb-containing minerals under a wide range of conditions, and so would be expected to be present in Pb-contaminated soils.…”