Spectroscopic evidence of uranium immobilization in acidic wetlands by natural organic matter and plant roots
- Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)
- Savannah River Site (SRS), Aiken, SC (United States). Savannah River Ecology Lab. (SREL)
- Princeton Univ., NJ (United States). Dept. of Civil and Environmental Engineering
- US Environmental Protection Agency (EPA), Cincinnati, OH (United States). National Risk Management Research Lab.
- Illinois Inst. of Technology, Chicago, IL (United States). Physics Dept. and CSRRI
- Canadian Light Sources, Inc., Saskatoon, SK (Canada)
- Univ. of Guelph, ON (Canada). Dept. of Physics
- Univ. of Chicago, IL (United States). Center for Advanced Radiation Sources (CARS)
Biogeochemistry of uranium in wetlands plays important roles in U immobilization in storage ponds of U mining and processing facilities but has not been well understood. The objective of this work was to study molecular mechanisms responsible for high U retention by Savannah River Site (SRS) wetland sediments under varying redox and acidic (pH = 2.6–5.8) conditions using U L₃-edge X-ray absorption spectroscopy. Uranium in the SRS wetland sediments existed primarily as U(VI) bonded as a bidentate to carboxylic sites (U–C bond distance at ~2.88 Å), rather than phenolic or other sites of natural organic matter (NOM). In microcosms simulating the SRS wetland processes, U immobilization on roots was two orders of magnitude higher than on the adjacent brown or more distant white sands in which U was U(VI). Uranium on the roots were both U(IV) and U(VI), which were bonded as a bidentate to carbon, but the U(VI) may also form a U phosphate mineral. After 140 days of air exposure, all U(IV) was re-oxidized to U(VI) but remained as a bidentate bonding to carbon. This study demonstrated NOM and plant roots can highly immobilize U(VI) in the SRS acidic sediments, which has significant implication for the long-term stewardship of U-contaminated wetlands.
- Research Organization:
- Savannah River Site (SRS), Aiken, SC (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23); Office of Environmental Management (EM)
- Grant/Contract Number:
- AC09-96SR18500; FC09-07SR22506; AC09-08SR22470; SC0006847; AC02-06CH11357; FG02-94ER14466
- OSTI ID:
- 1174137
- Alternate ID(s):
- OSTI ID: 1172416
- Report Number(s):
- SRNS-STI--2015-00177
- Journal Information:
- Environmental Science and Technology, Journal Name: Environmental Science and Technology Journal Issue: 5 Vol. 49; ISSN 0013-936X
- Publisher:
- American Chemical Society (ACS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
Uranium mobility and accumulation along the Rio Paguate, Jackpile Mine in Laguna Pueblo, NM
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journal | January 2017 |
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