Microscopically Focused Synchrotron X-ray Investigation of Selenium Speciation in Soils Developing on Reclaimed Mine Lands

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• 作者：Amy L. Ryser ; Daniel G. Strawn ; Matthew A. Marcus ; Sirine Fakra ; Jodi L. Johnson-Maynard ; and Gregory Mö ; ller
• 刊名：Environmental Science & Technology
• 出版年：2006
• 出版时间：January 15, 2006
• 年：2006
• 卷：40
• 期：2
• 页码：462 - 467
• 全文大小：319K
• 年卷期：v.40,no.2(January 15, 2006)
• ISSN：1520-5851

文摘

Chemical speciation determines Se solubility and thereforeits bioavailability and potential for transport in theenvironment. In this study we investigated the speciationof Se in soil developed on reclaimed mine sites in the U.S.Western Phosphate Resource Area (WPRA) using micro-X-ray absorption near-edge structure (ges/entities/mgr.gif">-XANES) spectroscopyand micro-X-ray fluorescence (ges/entities/mgr.gif">-XRF) mapping. Seleniumwas nonuniformly distributed in the soils and positivelycorrelated with Fe, Mn, Cu, Zn, and Ni. Sixteen points ofinterest (POI) from three soil samples were analyzed withges/entities/mgr.gif">-XANES spectroscopy. The XANES data indicated thatSe is present in the soils in at least three oxidation states,Se(-II, 0), Se(IV), and Se(VI). Selenides or elemental Sedominated 7 of the 16 POI. Selenate was the dominant speciesat only one of the POI. The remaining eight POI werecomposed of both Se(IV) and Se(VI), with minor Se(-II, 0)contributions. The results of this research suggest thatthe reduced Se species in the soil parent material areoxidizing to Se(VI), one of the more mobile species of Se inthe environment. This information can be used to betterpredict and manage Se availability in soils.