Complexation by Organic Matter Controls Uranium Mobility in Anoxic Sediments
[1];
[3];
[3];
[1]
- SLAC National Accelerator Lab., Menlo Park, CA (United States). Stanford Synchrotron Radiation Lightsource (SSRL)
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL)
- Stanford Univ., CA (United States). Earth System Science Dept.
Uranium contamination threatens the availability of safe and clean drinking water globally. This toxic element occurs both naturally and as a result of mining and ore-processing in alluvial sediments, where it accumulates as tetravalent U [U(IV)], a form once considered largely immobile. Changing hydrologic and geochemical conditions cause U to be released into groundwater. Knowledge of the chemical form(s) of U(IV) is essential to understand the release mechanism, however, the relevant U(IV) species are poorly characterized. There is growing belief that natural organic matter (OM) binds U(IV) and mediates its fate in the subsurface. In this work, we combined nanoscale imaging (nano secondary ion mass spectrometry and scanning transmission X-ray microscopy) with a density-based fractionation approach to physically and microscopically isolate organic and mineral matter from alluvial sediments contaminated with uranium. We identified two populations of U (dominantly +IV) in anoxic sediments. Uranium was retained on OM and adsorbed to particulate organic carbon, comprising both microbial and plant material. Surprisingly, U was also adsorbed to clay minerals and OM-coated clay minerals. The dominance of OM-associated U provides a framework to understand U mobility in the shallow subsurface, and, in particular, emphasizes roles for desorption and colloid formation in its mobilization.
- Research Organization:
- SLAC National Accelerator Lab., Menlo Park, CA (United States); Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL)
- Sponsoring Organization:
- USDOE Office of Science (SC), Biological and Environmental Research (BER); Natural Sciences and Engineering Research Council of Canada (NSERC); Canadian Institutes of Health Research (CIHR); National Research Council Canada (NRC); Western Economic Diversification Canada; Province of Saskatchewan
- Grant/Contract Number:
- AC02-76SF00515; AC05-76RL01830
- OSTI ID:
- 1605282
- Alternate ID(s):
- OSTI ID: 1600519
- Report Number(s):
- PNNL-SA-142857; TRN: US2104413
- Journal Information:
- Environmental Science and Technology, Vol. 54, Issue 3; ISSN 0013-936X
- Publisher:
- American Chemical Society (ACS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
Similar Records
The Effect of Bicarbonate on Autunite Dissolution in the Presence of Shewanella oneidensis under Oxygen Restricted Conditions - 16429
Oxidative Uranium Release from Anoxic Sediments under Diffusion-Limited Conditions