Evaluating chemical extraction techniques for the determination of uranium oxidation state in reduced aquifer sediments
Environmental Science & Technology
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Abstract
Extraction techniques utilizing high pH and (bi)carbonate concentrations were evaluated for their efficacy in determining the oxidation state of uranium (U) in reduced sediments collected from Rifle, CO. Differences in dissolved concentrations between oxic and anoxic extractions have been proposed as a means to quantify the U(VI) and U(IV) content of sediments. An additional step was added to anoxic extractions using a strong anion exchange resin to separate dissolved U(IV) and U(VI). X-ray spectroscopy showed that U(IV) in the sediments was present as polymerized precipitates similar to uraninite and/or less ordered U(IV), referred to as non-uraninite U(IV) species associated with biomass (NUSAB). Extractions of sediment containing both uraninite and NUSAB displayed higher dissolved uranium concentrations under oxic than anoxic conditions while extractions of sediment dominated by NUSAB resulted in identical dissolved U concentrations. Dissolved U(IV) was rapidly oxidized under anoxic conditions in all experiments. Uraninite reacted minimally under anoxic conditions but thermodynamic calculations show that its propensity to oxidize is sensitive to solution chemistry and sediment mineralogy. A universal method for quantification of U(IV) and U(VI) in sediments has not yet been developed but the chemical extractions, when combined with solid-phase characterization, have a narrow range of applicability for sediments without U(VI).
Suggested Citation
Stoliker, D., Campbell, K.M., Fox, P.M., Singer, D.M., Kaviani, N., Carey, M., Peck, N.E., Barger, J.R., Kent, D.B., Davis, J., 2013, Evaluating chemical extraction techniques for the determination of uranium oxidation state in reduced aquifer sediments: Environmental Science & Technology, v. 47, no. 16, p. 9225-9232, https://doi.org/10.1021/es401450v.
ISSN: 1520-5851 (online)
Study Area
| Publication type | Article |
|---|---|
| Publication Subtype | Journal Article |
| Title | Evaluating chemical extraction techniques for the determination of uranium oxidation state in reduced aquifer sediments |
| Series title | Environmental Science & Technology |
| DOI | 10.1021/es401450v |
| Volume | 47 |
| Issue | 16 |
| Publication Date | August 01, 2013 |
| Year Published | 2013 |
| Language | English |
| Publisher | American Chemical Society |
| Contributing office(s) | National Research Program - Western Branch |
| Description | 8 p. |
| Larger Work Type | Article |
| Larger Work Subtype | Journal Article |
| Larger Work Title | Environmental Science and Technology |
| First page | 9225 |
| Last page | 9232 |
| Country | United States |
| State | Colorado |
| City | Rifle |