Chromium speciation in highly polluted soils by X-ray Absorption Fine Structure

Chromium is a common contaminant in soil due to its frequent industrial application. For the past two decades, chromium is considered as one of the top 20 contaminants on the Superfund priority list of hazardous substances. Hexavalent Cr(VI) is carcinogenic and toxic for organisms. The quantification of Cr(VI) in the most Crpolluted soil samples is not accurate because high content in organic matter causes a considerable or complete reduction of Cr(VI) during phase extraction. Cr speciation by chemical analytical methods is rather complicated. XANES spectroscopy can probe all the irradiated chromium atoms in a sample to directly determine its chemical chromium composition. Different chromium species show unique spectral features that estimate different chromium oxidation states. A more complete characterization of chromium compounds in the soil will be derived from the quantitative EXAFS analysis and the comparison between XANES spectra of chromium in the soil and reference compounds.