Micro-spectroscopic investigation of selenium-bearing minerals from the Western US Phosphate Resource Area
Autor: | Jodi L. Johnson-Maynard, Matthew A. Marcus, Amy L. Ryser, Daniel G. Strawn, Mickey E. Gunter, Gregory Möller |
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Jazyk: | angličtina |
Rok vydání: | 2005 |
Předmět: |
chemistry.chemical_classification
lcsh:GE1-350 X-ray absorption spectroscopy Absorption spectroscopy Chemistry media_common.quotation_subject Analytical chemistry chemistry.chemical_element engineering.material XANES lcsh:Chemistry Speciation lcsh:QD1-999 Geochemistry and Petrology Environmental chemistry engineering Compounds of carbon Pyrite Oil shale Selenium lcsh:Environmental sciences media_common Research Article |
Zdroj: | Geochemical Transactions, Vol 6, Iss 1, p 1 (2005) Geochemical Transactions |
ISSN: | 1467-4866 |
Popis: | Mining activities in the US Western Phosphate Resource Area (WPRA) have released Se into the environment. Selenium has several different oxidation states and species, each having varying degrees of solubility, reactivity, and bioavailability. In this study we are investigating the speciation of Se in mine-waste rocks. Selenium speciation was determined using bulk and micro-x-ray absorption spectroscopy (XAS), as well as micro-x-ray fluorescence mapping. Rocks used for bulk-XAS were ground into fine powders. Shale used for micro-XAS was broken along depositional planes to expose unweathered surfaces. The near edge region of the XAS spectra (XANES) for the bulk rock samples revealed multiple oxidation states, with peaks indicative of Se(-II), Se(IV), and Se(+VI) species. Micro-XANES analysis of the shale indicated that three unique Se-bearing species were present. Using the XANES data together with ab initio fitting of the extended x-ray absorption fine structure region of the micro-XAS data (micro-EXAFS) the three Se-bearing species were identified as dzharkenite, a di-selenide carbon compound, and Se-substituted pyrite. Results from this research will allow for a better understanding of the biogeochemical cycling of Se in the WPRA. |
Databáze: | OpenAIRE |
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