期刊
ENVIRONMENTAL SCIENCE & TECHNOLOGY
卷 49, 期 5, 页码 2823-2832出版社
AMER CHEMICAL SOC
DOI: 10.1021/es505369g
关键词
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资金
- Subsurface Biogeochemistry Research program within the Department of Energy (DOE) Office of Sciences, Biological and Environmental Research
- U.S. DOE [DE-AC09-96SR18500]
- Savannah River Ecology Laboratory through a DOE [DE-FC09-07SR22506]
- DOE [DE-SC0006847]
- NSERC Discovery Grant
- EPA
- DOE Office of Science [DE-AC02-06CH11357]
- NSF's Earth Sciences [EAR-0217473]
- DOE's Geo-sciences [DE-FG02-94ER14466]
- State of Illinois
- U.S. DOE Office of Science, Office of Basic Energy Sciences [W-31-109-ENG-38]
- NSERC of Canada
- NRC of Canada
- Canadian Institutes of Health Research
- Province of Saskatchewan
- U.S. Department of Energy (DOE) [DE-SC0006847] Funding Source: U.S. Department of Energy (DOE)
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 L-3-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 similar to 2.88 angstrom), rather than phenolic or other sites of natural organic matter (NOM). In microcosms simulating the SRS wetland processes, U immobilization on roots was 2 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 reoxidized 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.
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