XAFS study of As-bearing mine tailings subjected to simulated human digestion
- Stanford Univ., CA (United States)
Mine tailings containing large amounts of As present a hazard for people living in desert communities such as Trona, CA, where they have been used as landscaping material. A group of researchers at U.C. Davis chemically simulated human digestion of the tailings to assess this risk, finding < 10% As released after the procedure. We have explored the use of x-ray absorption fine structure (XAFS) spectroscopy as a tool for determining the speciation of redox-sensitive elements such as As in mixtures of unknown, poorly ordered, potentially noncrystalline phases such as found in soils, sediments, and mine tailings. We collected XAFS data on three sets of pristine and simulated digestion tailings and determined the identity, number, and distance of atoms around the As out to {approximately}6 {Angstrom}. As{sup 5+}O{sub 4} is the primary As species in all samples, although minor As{sup 3}+O{sub 3} may be present in some samples. The quantity of Fe and/or Al atoms near the average As and the identification in some samples of As second neighbors suggests that As is sequestered in relatively insoluble, poorly ordered, impure precipitates such as Fe or Al hydrous oxides. These findings are in agreement with the low As mobility found in the simulated digestion study.
- OSTI ID:
- 126399
- Report Number(s):
- CONF-950402-; TRN: 95:006086-0383
- Resource Relation:
- Conference: 209. American Chemical Society (ACS) national meeting, Anaheim, CA (United States), 2-6 Apr 1995; Other Information: PBD: 1995; Related Information: Is Part Of 209th ACS national meeting; PB: 2088 p.
- Country of Publication:
- United States
- Language:
- English
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