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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. 2017. "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 = 2017,
month = 6
}

Journal Article:
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  • Data were obtained from uranium ore samples representing deposits above the water table, deposits just above and below perched water tables, and deposits at least 250 feet below the water table in the Hulett Creek area, Wyoming. The first uranium deposition occurred more than 250000 years ago for the deposits now at or above the water table. Approximately 60000 to 80000 years ago these deposits were oxidized, leached, and locally enriched. Accumulation of uranium in the deposits below the water table probably did not start before 180000 years ago and has continued to the present.
  • Todorokite, as one of three main Mn oxide phases present in oceanic Mn nodules and an active MnO{sub 6} octahedral molecular sieve (OMS), has garnered much interest; however, its formation pathway in natural systems is not fully understood. Todorokite is widely considered to form from layer structured Mn oxides with hexagonal symmetry, such as vernadite ({delta}-MnO{sub 2}), which are generally of biogenic origin. However, this geochemical process has not been documented in the environment or demonstrated in the laboratory, except for precursor phases with triclinic symmetry. Here we report on the formation of a nanoscale, todorokite-like phase from biogenic Mnmore » oxides produced by the freshwater bacterium Pseudomonas putida strain GB-1. At long- and short-range structural scales biogenic Mn oxides were transformed to a todorokite-like phase at atmospheric pressure through refluxing. Topotactic transformation was observed during the transformation. Furthermore, the todorokite-like phases formed via refluxing had thin layers along the c* axis and a lack of c* periodicity, making the basal plane undetectable with X-ray diffraction reflection. The proposed pathway of the todorokite-like phase formation is proposed as: hexagonal biogenic Mn oxide {yields} 10-{angstrom} triclinic phyllomanganate {yields} todorokite. These observations provide evidence supporting the possible bio-related origin of natural todorokites and provide important clues for understanding the transformation of biogenic Mn oxides to other Mn oxides in the environment. Additionally this method may be a viable biosynthesis route for porous, nano-crystalline OMS materials for use in practical applications.« less