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Title: Uranium Isotopic Fractionation Induced by U(VI) Adsorption onto Common Aquifer Minerals

Journal Article · · Environmental Science and Technology
 [1];  [1];  [2];  [1]
  1. Univ. of Illinois, Champaign, IL (United States). Dept. of Geology
  2. Oregon State Univ., Corvallis, OR (United States). College of Earth, Ocean, and Atmospheric Sciences

Uranium groundwater contamination due to U mining and processing affects numerous sites globally. Bioreduction of soluble, mobile U(VI) to U(IV)-bearing solids is potentially a very effective remediation strategy. Uranium isotopes (238U/235U) have been utilized to track the progress of microbial reduction, with laboratory and field studies finding a ~1‰ isotopic fractionation, with the U(IV) product enriched in 238U. However, the isotopic fractionation produced by adsorption may complicate the use of 238U/235U to trace microbial reduction. A previous study found that adsorption of U(VI) onto Mn oxides produced a -0.2‰ fractionation with the adsorbed U(VI) depleted in 238U. In this paper, adsorption to quartz, goethite, birnessite, illite, and aquifer sediments induced an average isotopic fractionation of -0.15‰ with the adsorbed U(VI) isotopically lighter than coexisting aqueous U(VI). In bicarbonate-bearing matrices, the fractionation depended little on the nature of the sorbent, with only birnessite producing an atypically large fractionation. In the case of solutions with ionic strengths much lower than those of typical groundwater, less isotopic fractionation was produced than U(VI) solutions with greater ionic strength. Finally, studies using U isotope data to assess U(VI) reduction must consider adsorption as a lesser, but significant isotope fractionation process.

Research Organization:
Univ. of Illinois at Urbana-Champaign, IL (United States)
Sponsoring Organization:
USDOE Office of Science (SC), Biological and Environmental Research (BER)
DOE Contract Number:
SC0006755
OSTI ID:
1460249
Journal Information:
Environmental Science and Technology, Vol. 50, Issue 22; ISSN 0013-936X
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English

References (52)

Uranyl Surface Complexes Formed on Subsurface Media from DOE Facilities journal January 2002
Impact of Uranyl−Calcium−Carbonato Complexes on Uranium(VI) Adsorption to Synthetic and Natural Sediments journal February 2010
Stimulating the In Situ Activity of Geobacter Species To Remove Uranium from the Groundwater of a Uranium-Contaminated Aquifer journal October 2003
Bicarbonate impact on U(VI) bioreduction in a shallow alluvial aquifer journal February 2015
Global enhancement of ocean anoxia during Oceanic Anoxic Event 2: A quantitative approach using U isotopes journal April 2010
Uranium isotope fractionation in Saanich Inlet: A modern analog study of a paleoredox tracer journal March 2015
Low-temperature isotopic fractionation of uranium journal December 2007
Uranium isotope fractionation suggests oxidative uranium mobilization at 2.50Ga journal December 2013
Experimentally Determined Uranium Isotope Fractionation During Reduction of Hexavalent U by Bacteria and Zero Valent Iron journal November 2006
Preparation, characterization and aging of δ-MnO2, for use in trace metal speciation studies journal March 1987
Physico-Chemical Heterogeneity of Organic-Rich Sediments in the Rifle Aquifer, CO: Impact on Uranium Biogeochemistry journal December 2015
Molecular-Scale Structure of Uranium(VI) Immobilized with Goethite and Phosphate journal May 2012
Least squares fitting of a straight line with correlated errors journal January 1968
Adsorption and Transport of Uranium(VI) in Subsurface Media journal January 2000
Isotopic Evidence for Reductive Immobilization of Uranium Across a Roll-Front Mineral Deposit journal June 2016
Rate-limited U(VI) desorption during a small-scale tracer test in a heterogeneous uranium-contaminated aquifer: RATE-LIMITED U(VI) DESORPTION IN A U-CONTAMINATED AQUIFER journal May 2012
Uranyl sorption onto birnessite: A surface complexation modeling and EXAFS study journal May 2014
A reevaluation of the oceanic uranium budget for the Holocene journal October 2002
Uranium isotope systematics of ferromanganese crusts in the Pacific Ocean: Implications for the marine 238 U/ 235 U isotope system journal December 2014
The structure of uranium (VI) sorption complexes on silica, alumina, and montmorillonite journal July 2000
Coupled molybdenum, iron and uranium stable isotopes as oceanic paleoredox proxies during the Paleoproterozoic Shunga Event journal December 2013
Using Chromium Stable Isotope Ratios To Quantify Cr(VI) Reduction:  Lack of Sorption Effects journal July 2004
Uranium Mill Tailings: Geochemistry, Mineralogy, and Environmental Impact journal December 2006
Geochemical, mineralogical and microbiological characteristics of sediment from a naturally reduced zone in a uranium-contaminated aquifer journal August 2012
Adsorption of uranyl onto ferric oxyhydroxides: Application of the surface complexation site-binding model journal September 1985
Uranium Reduction journal October 2006
Chemical reactions of uranium in ground water at a mill tailings site journal November 1998
Uranyl adsorption onto montmorillonite: Evaluation of binding sites and carbonate complexation journal June 2005
Reaction Mechanisms of Smectite Illitization Associated with Hydrothermal Alteration from Ponza Island, Italy journal January 2000
Natural fractionation of 238U/235U journal January 2008
Molecular Dynamics Study of Aqueous Uranyl Interactions with Quartz (010) journal January 2002
Uranium 238 U/ 235 U Isotope Ratios as Indicators of Reduction: Results from an in situ Biostimulation Experiment at Rifle, Colorado, U.S.A. journal August 2010
Determination of Uranyl Incorporation into Biogenic Manganese Oxides Using X-ray Absorption Spectroscopy and Scattering journal February 2006
Natural variations in uranium isotope ratios of uranium ore concentrates: Understanding the 238U/235U fractionation mechanism journal March 2010
Rapid expansion of oceanic anoxia immediately before the end-Permian mass extinction journal October 2011
Estimating Precision Using Duplicate Measurements journal September 2009
Uranium isotopes distinguish two geochemically distinct stages during the later Cambrian SPICE event journal September 2014
Uranium(VI) Sorption Complexes on Montmorillonite as a Function of Solution Chemistry journal January 2001
Fractionation of 238U/235U by reduction during low temperature uranium mineralisation processes journal February 2014
Uranium isotopic fractionation factors during U(VI) reduction by bacterial isolates journal July 2014
No Measurable Changes in 238 U/ 235 U due to Desorption–Adsorption of U(VI) from Groundwater at the Rifle, Colorado, Integrated Field Research Challenge Site journal February 2013
Uranium isotopes fingerprint biotic reduction journal April 2015
Uranium and molybdenum isotope evidence for an episode of widespread ocean oxygenation during the late Ediacaran Period journal May 2015
Uranium Isotope Fractionation during Adsorption to Mn-Oxyhydroxides journal February 2011
The effect of calcium on aqueous uranium(VI) speciation and adsorption to ferrihydrite and quartz journal March 2006
Uranium concentrations and 238U/235U isotope ratios in modern carbonates from the Bahamas: Assessing a novel paleoredox proxy journal December 2013
Variations in 238U/235U in uranium ore deposits: Isotopic signatures of the U reduction process? journal July 2009
Uranium in the oceans: Where it goes and why journal July 1991
Isotopic and Geochemical Tracers for U(VI) Reduction and U Mobility at an in Situ Recovery U Mine journal May 2015
Zinc isotope fractionation during adsorption onto Mn oxyhydroxide at low and high ionic strength journal May 2015
Uranium isotope fractionation during coprecipitation with aragonite and calcite journal September 2016
Geochemical and mineralogical investigation of uranium in multi-element contaminated, organic-rich subsurface sediment journal March 2014