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Title: Solid-phase arsenic speciation in aquifer sediments: A micro-X-ray absorption spectroscopy approach for quantifying trace-level speciation

Authors:
; ; ; ; ; ;
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
Sponsoring Org.:
OTHER U.S. STATESOTHER U.S. GOVERNMENTUNIVERSITY
OSTI Identifier:
1368237
Resource Type:
Journal Article
Resource Relation:
Journal Name: Geochimica et Cosmochimica Acta; Journal Volume: 211
Country of Publication:
United States
Language:
ENGLISH

Citation Formats

Nicholas, Sarah L., Erickson, Melinda L., Woodruff, Laurel G., Knaeble, Alan R., Marcus, Matthew A., Lynch, Joshua K., and Toner, Brandy M.. Solid-phase arsenic speciation in aquifer sediments: A micro-X-ray absorption spectroscopy approach for quantifying trace-level speciation. United States: N. p., 2017. Web. doi:10.1016/j.gca.2017.05.018.
Nicholas, Sarah L., Erickson, Melinda L., Woodruff, Laurel G., Knaeble, Alan R., Marcus, Matthew A., Lynch, Joshua K., & Toner, Brandy M.. Solid-phase arsenic speciation in aquifer sediments: A micro-X-ray absorption spectroscopy approach for quantifying trace-level speciation. United States. doi:10.1016/j.gca.2017.05.018.
Nicholas, Sarah L., Erickson, Melinda L., Woodruff, Laurel G., Knaeble, Alan R., Marcus, Matthew A., Lynch, Joshua K., and Toner, Brandy M.. 2017. "Solid-phase arsenic speciation in aquifer sediments: A micro-X-ray absorption spectroscopy approach for quantifying trace-level speciation". United States. doi:10.1016/j.gca.2017.05.018.
@article{osti_1368237,
title = {Solid-phase arsenic speciation in aquifer sediments: A micro-X-ray absorption spectroscopy approach for quantifying trace-level speciation},
author = {Nicholas, Sarah L. and Erickson, Melinda L. and Woodruff, Laurel G. and Knaeble, Alan R. and Marcus, Matthew A. and Lynch, Joshua K. and Toner, Brandy M.},
abstractNote = {},
doi = {10.1016/j.gca.2017.05.018},
journal = {Geochimica et Cosmochimica Acta},
number = ,
volume = 211,
place = {United States},
year = 2017,
month = 8
}
  • Arsenic (As) is a geogenic contaminant affecting groundwater in geologically diverse systems globally. Arsenic release from aquifer sediments to groundwater is favored when biogeochemical conditions, especially oxidation-reduction (redox) potential, in aquifers fluctuate. The specific objective of this research is to identify the solid-phase sources and geochemical mechanisms of release of As in aquifers of the Des Moines Lobe glacial advance. The overarching concept is that conditions present at the aquifer-aquitard interfaces promote a suite of geochemical reactions leading to mineral alteration and release of As to groundwater. A microprobe X-ray absorption spectroscopy (μXAS) approach is developed and applied to rotosonicmore » drill core samples to identify the solid-phase speciation of As in aquifer, aquitard, and aquifer-aquitard interface sediments. This approach addresses the low solid-phase As concentrations, as well as the fine-scale physical and chemical heterogeneity of the sediments. The spectroscopy data are analyzed using novel cosine-distance and correlation-distance hierarchical clustering for Fe 1s and As 1s μXAS datasets. The solid-phase Fe and As speciation is then interpreted using sediment and well-water chemical data to propose solid-phase As reservoirs and release mechanisms. The results confirm that in two of the three locations studied, the glacial sediment forming the aquitard is the source of As to the aquifer sediments. The results are consistent with three different As release mechanisms: (1) desorption from Fe (oxyhydr)oxides, (2) reductive dissolution of Fe (oxyhydr)oxides, and (3) oxidative dissolution of Fe sulfides. The findings confirm that glacial sediments at the interface between aquifer and aquitard are geochemically active zones for As. The diversity of As release mechanisms is consistent with the geographic heterogeneity seen in the distribution of elevated-As wells.« less
  • Identification of arsenic chemical species at a sub-cellular level is a key to understanding the mechanisms involved in arsenic toxicology and antitumor pharmacology. When performed with a microbeam, X-ray absorption near-edge structure ({mu}-XANES) enables the direct speciation analysis of arsenic in sub-cellular compartments avoiding cell fractionation and other preparation steps that might modify the chemical species. This methodology couples tracking of cellular organelles in a single cell by confocal or epifluorescence microscopy with local analysis of chemical species by {mu}-XANES. Here we report the results obtained with a {mu}-XANES experimental setup based on Kirkpatrick-Baez X-ray focusing optics that maintains highmore » flux of incoming radiation (>10{sup 11} ph/s) at micrometric spatial resolution (1.5x4.0 {mu}m{sup 2}). This original experimental setup enabled the direct speciation analysis of arsenic in sub-cellular organelles with a 10{sup -15} g detection limit. {mu}-XANES shows that inorganic arsenite, As(OH){sub 3}, is the main form of arsenic in the cytosol, nucleus, and mitochondrial network of cultured cancer cells exposed to As{sub 2}O{sub 3}. On the other hand, a predominance of As(III) species is observed in HepG2 cells exposed to As(OH){sub 3} with, in some cases, oxidation to a pentavalent form in nuclear structures of HepG2 cells. The observation of intra-nuclear mixed redox states suggests an inter-individual variability in a cell population that can only be evidenced with direct sub-cellular speciation analysis.« less
  • There has been substantial interest recently in chemical speciation and species transformations of uranium in contaminated soils, sediments, and nuclear wastes, both from the standpoint of predicting its mobility to and within subsurface environments and for developing effective strategies for remediating contaminated sites. We exploited the microanalytical capabilities of beam line X-26A at Brookhaven National Laboratory to collect XANES and SXRF spectra on localized (50-300-[mu]m) regions within a number of U-contaminated soils and sediments. This provided specific information on U oxidation states, qualitative information on U-bonding environments, and information on associated elemental distributions. 26 refs., 4 figs.
  • No abstract prepared.