Chromium Speciation in the Size-Fractions of a Soil Polluted by Weathered Chromate Ore Process Residue Using Synchrotron X-ray Analysis
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The chromate ore process residues (COPR) polluted soil was physically separated into coarse sand (2.000–0.425 mm), fine sand (0.425–0.053 mm) and silt to clay (< 0.053 mm) fractions. The Cr speciation was characterized by synchrotron based micro X-ray fluorescence (µ-XRF) and micro X-ray absorption near-edge spectra (µ-XANES). The results indicated that Cr was bearing both in COPR parent minerals and hydrated products and was dominated by Cr(III) in three size-fractions. The synchrotron results indicated that Cr(III) was dominated by chromite, organic matter bound Cr(III) and particle adsorbed Cr3+ in the selected hotspots from the coarse sand, fine sand and silt to clay sized fraction, respectively. While Cr(VI) occurred in the form of CrO42− in the selected hotspots from three size fractions. The difference of Cr(III) species in the size-fractions suggested that higher edaphic effects occurred in the fine size-fractions than in the coarse size-fraction for the weathered COPR.
KeywordsSoil pollution Chromium slag Particle size Micro X-ray fluorescence (µ-XRF) Micro X-ray absorption near-edge spectra (µ-XANES)
This research was funded by Zhejiang Agriculture and Forestry University Research Funding (2017FR021) and the National Natural Science Foundation of China (41771351). We are grateful to the beamline (BL15U1) of Shanghai Synchrotron Radiation Facility (SSRF) for providing µ-XRF and µ-XANES analysis. Thanks are also given to the anonymous reviewers for their suggestive comments on the paper improvement.
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