Retention and chemical speciation of uranium in an oxidized wetland sediment from the Savannah River Site

Dien Li, John C. Seaman, Hyun Shik Chang, Peter R. Jaffe, Paul Koster van Groos, De Tong Jiang, Ning Chen, Jinru Lin, Zachary Arthur, Yuanming Pan, Kirk G. Scheckel, Matthew Newville, Antonio Lanzirotti, Daniel I. Kaplan

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26 Scopus citations

Abstract

Uranium speciation and retention mechanisms onto Savannah River Site (SRS) wetland sediments was studied using batch (ad)sorption experiments, sequential extraction, U L3-edge X-ray absorption near-edge structure (XANES) spectroscopy, fluorescence mapping and μ-XANES. Under oxidized conditions, U was highly retained by the SRS wetland sediments. In contrast to other similar but much lower natural organic matter (NOM) sediments, significant sorption of U onto the SRS sediments was observed at pH<4 and pH>8. Sequential extraction indicated that the U species were primarily associated with the acid soluble fraction (weak acetic acid extractable) and organic fraction (Na-pyrophosphate extractable). Uranium L3-edge XANES spectra of the U-bound sediments were nearly identical to that of uranyl acetate. Based on fluorescence mapping, U and Fe distributions in the sediment were poorly correlated, U was distributed throughout the sample and did not appear as isolated U mineral phases. The primary oxidation state of U in these oxidized sediments was U(VI), and there was little evidence that the high sorptive capacity of the sediments could be ascribed to abiotic or biotic reduction to the less soluble U(IV) species or to secondary mineral formation. Collectively, this study suggests that U may be strongly bound to wetland sediments, not only under reducing conditions by reductive precipitation, but also under oxidizing conditions through NOM-uranium bonding.

Original languageEnglish (US)
Pages (from-to)40-46
Number of pages7
JournalJournal of Environmental Radioactivity
Volume131
DOIs
StatePublished - May 2014

All Science Journal Classification (ASJC) codes

  • Environmental Chemistry
  • Waste Management and Disposal
  • Pollution
  • Health, Toxicology and Mutagenesis

Keywords

  • Chemical speciation
  • Retention
  • Spectroscopy
  • Uranium
  • Wetland sediments

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    Li, D., Seaman, J. C., Chang, H. S., Jaffe, P. R., Koster van Groos, P., Jiang, D. T., Chen, N., Lin, J., Arthur, Z., Pan, Y., Scheckel, K. G., Newville, M., Lanzirotti, A., & Kaplan, D. I. (2014). Retention and chemical speciation of uranium in an oxidized wetland sediment from the Savannah River Site. Journal of Environmental Radioactivity, 131, 40-46. https://doi.org/10.1016/j.jenvrad.2013.10.017