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Title: Selenium speciation in phosphate mine soils and evaluation of a sequential extraction procedure using XAFS

Abstract

Selenium is a trace element found in western US soils, where ingestion of Se-accumulating plants has resulted in livestock fatalities. Therefore, a reliable understanding of Se speciation and bioavailability is critical for effective mitigation. Sequential extraction procedures (SEP) are often employed to examine Se phases and speciation in contaminated soils but may be limited by experimental conditions. We examined the validity of a SEP using X-ray absorption spectroscopy (XAS) for both whole and a sequence of extracted soils. The sequence included removal of soluble, PO4-extractable, carbonate, amorphous Fe-oxide, crystalline Fe-oxide, organic, and residual Se forms. For whole soils, XANES analyses indicated Se(0) and Se(-II) predominated, with lower amounts of Se(IV) present, related to carbonates and Fe-oxides. Oxidized Se species were more elevated and residual/elemental Se was lower than previous SEP results from ICP-AES suggested. For soils from the SEP sequence, XANES results indicated only partial recovery of carbonate, Fe-oxide and organic Se. This suggests Se was incompletely removed during designated extractions, possibly due to lack of mineral solubilization or reagent specificity. Selenium fractions associated with Fe-oxides were reduced in amount or removed after using hydroxylamine HCl for most soils examined. XANES results indicate partial dissolution of solid-phases may occur duringmore » extraction processes. This study demonstrates why precautions should be taken to improve the validity of SEPs. Mineralogical and chemical characterizations should be completed prior to SEP implementation to identify extractable phases or mineral components that may influence extraction effectiveness. Sequential extraction procedures can be appropriately tailored for reliable quantification of speciation in contaminated soils.« less

Authors:
; ; ORCiD logo;
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
Sponsoring Org.:
USEPA
OSTI Identifier:
1400294
Resource Type:
Journal Article
Resource Relation:
Journal Name: Environmental Pollution; Journal Volume: 229; Journal Issue: C
Country of Publication:
United States
Language:
ENGLISH
Subject:
54 ENVIRONMENTAL SCIENCES

Citation Formats

Favorito, Jessica E., Luxton, Todd P., Eick, Matthew J., and Grossl, Paul R.. Selenium speciation in phosphate mine soils and evaluation of a sequential extraction procedure using XAFS. United States: N. p., 2017. Web. doi:10.1016/j.envpol.2017.07.071.
Favorito, Jessica E., Luxton, Todd P., Eick, Matthew J., & Grossl, Paul R.. Selenium speciation in phosphate mine soils and evaluation of a sequential extraction procedure using XAFS. United States. doi:10.1016/j.envpol.2017.07.071.
Favorito, Jessica E., Luxton, Todd P., Eick, Matthew J., and Grossl, Paul R.. Sun . "Selenium speciation in phosphate mine soils and evaluation of a sequential extraction procedure using XAFS". United States. doi:10.1016/j.envpol.2017.07.071.
@article{osti_1400294,
title = {Selenium speciation in phosphate mine soils and evaluation of a sequential extraction procedure using XAFS},
author = {Favorito, Jessica E. and Luxton, Todd P. and Eick, Matthew J. and Grossl, Paul R.},
abstractNote = {Selenium is a trace element found in western US soils, where ingestion of Se-accumulating plants has resulted in livestock fatalities. Therefore, a reliable understanding of Se speciation and bioavailability is critical for effective mitigation. Sequential extraction procedures (SEP) are often employed to examine Se phases and speciation in contaminated soils but may be limited by experimental conditions. We examined the validity of a SEP using X-ray absorption spectroscopy (XAS) for both whole and a sequence of extracted soils. The sequence included removal of soluble, PO4-extractable, carbonate, amorphous Fe-oxide, crystalline Fe-oxide, organic, and residual Se forms. For whole soils, XANES analyses indicated Se(0) and Se(-II) predominated, with lower amounts of Se(IV) present, related to carbonates and Fe-oxides. Oxidized Se species were more elevated and residual/elemental Se was lower than previous SEP results from ICP-AES suggested. For soils from the SEP sequence, XANES results indicated only partial recovery of carbonate, Fe-oxide and organic Se. This suggests Se was incompletely removed during designated extractions, possibly due to lack of mineral solubilization or reagent specificity. Selenium fractions associated with Fe-oxides were reduced in amount or removed after using hydroxylamine HCl for most soils examined. XANES results indicate partial dissolution of solid-phases may occur during extraction processes. This study demonstrates why precautions should be taken to improve the validity of SEPs. Mineralogical and chemical characterizations should be completed prior to SEP implementation to identify extractable phases or mineral components that may influence extraction effectiveness. Sequential extraction procedures can be appropriately tailored for reliable quantification of speciation in contaminated soils.},
doi = {10.1016/j.envpol.2017.07.071},
journal = {Environmental Pollution},
number = C,
volume = 229,
place = {United States},
year = {Sun Oct 01 00:00:00 EDT 2017},
month = {Sun Oct 01 00:00:00 EDT 2017}
}