skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Biogenic non-crystalline U (IV) revealed as major component in uranium ore deposits

Abstract

Historically, it is believed that crystalline uraninite, produced via the abiotic reduction of hexavalent uranium (U (VI)) is the dominant reduced U species formed in low-temperature uranium roll-front ore deposits. Here we show that non-crystalline U (IV) generated through biologically mediated U (VI) reduction is the predominant U (IV) species in an undisturbed U roll-front ore deposit in Wyoming, USA. Characterization of U species revealed that the majority (~58-89%) of U is bound as U (IV) to C-containing organic functional groups or inorganic carbonate, while uraninite and U (VI) represent only minor components. The uranium deposit exhibited mostly 238U-enriched isotope signatures, consistent with largely biotic reduction of U (VI) to U (IV). This finding implies that biogenic processes are more important to uranium ore genesis than previously understood. The predominance of a relatively labile form of U (IV) also provides an opportunity for a more economical and environmentally benign mining process, as well as the design of more effective post-mining restoration strategies and human health-risk assessment.

Authors:
 [1];  [2];  [3];  [4];  [4];  [5]; ORCiD logo [6]
  1. Colorado State Univ., Fort Collins, CO (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  2. U.S. Geological Survey, Boulder, CO (United States)
  3. EXAFS Analysis, Bolingbrook, IL (United States)
  4. Leibniz Univ. Hannover, Hannover (Germany)
  5. Ecole Polytechnique Federale de Lausanne, Lausanne (Switzerland)
  6. Colorado State Univ., Fort Collins, CO (United States)
Publication Date:
Research Org.:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1379874
Grant/Contract Number:
AC02-05CH11231
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Nature Communications
Additional Journal Information:
Journal Volume: 8; Journal ID: ISSN 2041-1723
Publisher:
Nature Publishing Group
Country of Publication:
United States
Language:
English
Subject:
58 GEOSCIENCES; Element cycles; Geochemistry; Microbial ecology; Nuclear waste

Citation Formats

Bhattacharyya, Amrita, Campbell, Kate M., Kelly, Shelly D., Roebbert, Yvonne, Weyer, Stefan, Bernier-Latmani, Rizlan, and Borch, Thomas. Biogenic non-crystalline U(IV) revealed as major component in uranium ore deposits. United States: N. p., 2017. Web. doi:10.1038/ncomms15538.
Bhattacharyya, Amrita, Campbell, Kate M., Kelly, Shelly D., Roebbert, Yvonne, Weyer, Stefan, Bernier-Latmani, Rizlan, & Borch, Thomas. Biogenic non-crystalline U(IV) revealed as major component in uranium ore deposits. United States. doi:10.1038/ncomms15538.
Bhattacharyya, Amrita, Campbell, Kate M., Kelly, Shelly D., Roebbert, Yvonne, Weyer, Stefan, Bernier-Latmani, Rizlan, and Borch, Thomas. Thu . "Biogenic non-crystalline U(IV) revealed as major component in uranium ore deposits". United States. doi:10.1038/ncomms15538. https://www.osti.gov/servlets/purl/1379874.
@article{osti_1379874,
title = {Biogenic non-crystalline U(IV) revealed as major component in uranium ore deposits},
author = {Bhattacharyya, Amrita and Campbell, Kate M. and Kelly, Shelly D. and Roebbert, Yvonne and Weyer, Stefan and Bernier-Latmani, Rizlan and Borch, Thomas},
abstractNote = {Historically, it is believed that crystalline uraninite, produced via the abiotic reduction of hexavalent uranium (U(VI)) is the dominant reduced U species formed in low-temperature uranium roll-front ore deposits. Here we show that non-crystalline U(IV) generated through biologically mediated U(VI) reduction is the predominant U(IV) species in an undisturbed U roll-front ore deposit in Wyoming, USA. Characterization of U species revealed that the majority (~58-89%) of U is bound as U(IV) to C-containing organic functional groups or inorganic carbonate, while uraninite and U(VI) represent only minor components. The uranium deposit exhibited mostly 238U-enriched isotope signatures, consistent with largely biotic reduction of U(VI) to U(IV). This finding implies that biogenic processes are more important to uranium ore genesis than previously understood. The predominance of a relatively labile form of U(IV) also provides an opportunity for a more economical and environmentally benign mining process, as well as the design of more effective post-mining restoration strategies and human health-risk assessment.},
doi = {10.1038/ncomms15538},
journal = {Nature Communications},
number = ,
volume = 8,
place = {United States},
year = {Thu Jun 01 00:00:00 EDT 2017},
month = {Thu Jun 01 00:00:00 EDT 2017}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record

Citation Metrics:
Cited by: 2works
Citation information provided by
Web of Science

Save / Share:
  • Sediment column experiments were performed to quantify the effect of biogenic iron sulfide precipitates on the stability of bioreduced uranium during and after a simulated bioremediation scenario. In particular, this study examined the effect of different oxidants (dissolved oxygen and nitrate) on biogenic U(IV) oxidation in sediment that experienced significant sulfate reduction in addition to Fe(III) and U(VI) reduction. The experimental set-up included five replicate columns (each 5 cm in diameter, 15 cm long and packed with background sediment from a site contaminated with uranium) that were bioreduced for 70 days by injecting a nutrient media containing 3 mM acetatemore » and 6 mM sulfate prior to oxidation. Upon oxidation, iron sulfide precipitates formed during bioreduction acted as a buffer to partially prevent biogenic U(IV) oxidation. The iron sulfides were more effective at protecting biogenic U(IV) from oxidation when dissolved oxygen was the oxidant compared to nitrate. A constant supply of 0.25 mM and 1.6 mM nitrate over a 50 day period resulted in uranium resolubilization of 11% and 60%, respectively, while less than 1% of the uranium was resolubilized in the column supplied 0.27 mM dissolved oxygen during the same time period. Over time, oxidation increased pore water channeling, which was more pronounced during oxidation with nitrate. Finally, increased channeling with time of oxidation could affect the transport of an oxidant through the previously reduced zone, and hence the oxidation dynamics of the reduced species.« less
  • The Branch of Uranium and Thorium Resources is within the U.S. Geological Survey's Geologic Division and is the main uranium research element in the Department of Interior. The Uranium and Thorium Branch currently maintains 66 uranium research projects, each of which is headed by an experienced uranium geologist, geochemist, geophysicist, or chemist. Present program activities are: uranium geochemistry and mineralogy - 35%; uranium in sedimentary environments - 28%; uranium in igneous and metamorphic environments 10%; uranium geophysics - 20%; uranium resources assessment - 5%; thorium investigations and assessment - 2%. The percentages are the USGS base funding. Each of themore » program activities was briefly discussed. Results from the Branch program will be published as government reports and maps or in various scientific journals. Information of an urgent nature will be officially released by open-file as soon as it is prepared. (DP)« less
  • A sample from the Oklo deposit containing about 0.51 atom percent /sup 235/U (by mass spectrometer) was analyzed by a gamma-ray spectrometer system, using a high-purity planar germanium detector. The /sup 238/U was determined from its daughter's (/sup 234/Th) 63.3 keV photopeak; the /sup 235/U was determined from its 143.8 and 163.4 keV photopeaks. The ratios of these photopeaks were compared with that from a standard having normal uranium isotopic content; the resulting calculations give a /sup 235/U abundance of 0.54 atom percent in the Oklo sample. The gamma-ray spectrum also contains lines from five other isotopes in the uraniummore » series, which indicate the Oklo sample to be at or near secular equilibrium, as the time elapsed since the nuclear reaction ended was sufficient to permit the daughters to achieve equilibrium.« less
  • Two-Dimensional (2D) Correlation Spectroscopy was used to resolve the positions and correlations among U4f primary peaks and satellite structures that evolved as U VI was progressively reduced by a constant high flux of monochromatic Al Kα X-rays during X-ray photoelectron spectroscopy (XPS). Synchronous and asynchronous 2D maps of these results are consistent with previous assignments to U IV, U V and U VI components of the solid. The synchronous spectra confirmed the negative correlation between U VI and U IV components. The asynchronous spectra displayed cross-peaks that were characteristic of peak shift and confirmed the role of U V asmore » a reactive intermediate in the reduction reaction of U VI to U IV. Simulations of 2D correlation maps using synthetic spectra of the primary peaks showed that the presence of highly overlapped peaks centered within 2 eV cannot be distinguished without the presence of additional cross-peaks. The maps have therefore confirmed the existence of three dominant oxidation states, and identified positions of U IV, U V, and U VI U4f primary peaks and satellite structures that are consistent with previous peak-fitting efforts. Satellite structures also showed out-of-phase correlations among the different oxidation states, confirming previous assignments.« less