Uranium and Nickel Partitioning in a Contaminated Riparian Wetland
- Savannah River Site (SRS), Aiken, SC (United States). Savannah River Ecology Laboratory (SREL); Savannah River Ecology Laboratory - University of Georgia
- Argonne National Laboratory (ANL), Argonne, IL (United States); Bulgarian Academy of Sciences, Sofia (Bulgaria)
- Argonne National Laboratory (ANL), Argonne, IL (United States)
- Savannah River Site (SRS), Aiken, SC (United States). Savannah River Ecology Laboratory (SREL)
- Savannah River Site (SRS), Aiken, SC (United States). Savannah River Mission Completion (SRMC)
Uranium (U) and nickel (Ni) released 50 years ago have been immobilized in the Tims Branch wetlands located on the Savannah River Site in the United States. Sediments were collected from seven locations to identify the factors responsible for this attenuation. Ni and U contents in the solids were significantly correlated, suggesting that depositional as opposed to chemical processes contributed to their spatial distribution. Based on sequential extractions, 63 ± 16% of the U was partitioned into the organic fraction, whereas Ni was distributed between several sediment fractions. An inverse pH-organic matter (OM) correlation and positive correlations of OM with total U and organic-bound U/Ni suggest that increased OM preservation and binding to the mineral surfaces were likely responsible for Ni- and especially U-sediment retention (Tims Branch pH = 4.84 ± 0.68). EXAFS analysis indicated the predominance of U(VI) coordinated with clay minerals (~65%), together with ~35% coordinated to either OM (in areas with elevated OM levels) or iron oxides. The desorption-Kd coefficients of U (3972 ± 1370 L/kg) and Ni (30 ± 8 L/kg) indicate that dissolved Ni poses a greater long-term risk than dissolved U for migrating downstream. This study suggests that a delicate balance of geochemical properties controls whether wetlands behave as sinks or sources of contaminants.
- Research Organization:
- Argonne National Laboratory (ANL), Argonne, IL (United States); Savannah River Site (SRS), Aiken, SC (United States). Savannah River Ecology Laboratory (SREL)
- Sponsoring Organization:
- USDOE Office of Environmental Management (EM); USDOE Office of Science (SC), Biological and Environmental Research (BER). Earth & Environmental Systems Science (EESS)
- Grant/Contract Number:
- AC02-06CH11357; EM0005228
- OSTI ID:
- 2350789
- Alternate ID(s):
- OSTI ID: 2468634
- Journal Information:
- Water (Basel), Journal Name: Water (Basel) Journal Issue: 7 Vol. 16; ISSN 2073-4441
- Publisher:
- MDPICopyright Statement
- Country of Publication:
- United States
- Language:
- English
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