Long-term tracking of the microbiology of uranium-amended water-saturated bentonite microcosms: A mechanistic characterization of U speciation.

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  • Additional Information
    • Source:
      Publisher: Elsevier Country of Publication: Netherlands NLM ID: 9422688 Publication Model: Print-Electronic Cited Medium: Internet ISSN: 1873-3336 (Electronic) Linking ISSN: 03043894 NLM ISO Abbreviation: J Hazard Mater Subsets: MEDLINE
    • Publication Information:
      Original Publication: Amsterdam : Elsevier,
    • Subject Terms:
      Bentonite*/chemistry ; Uranium*/metabolism; Bacteria/genetics ; Bacteria/metabolism ; Radioactive Waste ; Water Pollutants, Radioactive/metabolism ; Groundwater/microbiology
    • Abstract:
      Deep geological repositories (DGRs) stand out as one of the optimal options for managing high-level radioactive waste (HLW) such as uranium (U) in the near future. Here, we provide novel insights into microbial behavior in the DGR bentonite barrier, addressing potential worst-case scenarios such as waste leakage (e.g., U) and groundwater infiltration of electron rich donors in the bentonite. After a three-year anaerobic incubation, Illumina sequencing results revealed a bacterial diversity dominated by anaerobic and spore-forming microorganisms mainly from the phylum Firmicutes. Highly U tolerant and viable bacterial isolates from the genera Peribacillus, Bacillus, and some SRB such as Desulfovibrio and Desulfosporosinus, were enriched from U-amended bentonite. The results obtained by XPS and XRD showed that U was present as U(VI) and as U(IV) species. Regarding U(VI), we have identified biogenic U(VI) phosphates, U(UO 2 )·(PO 4 ) 2, located in the inner part of the bacterial cell membranes in addition to U(VI)-adsorbed to clays such as montmorillonite. Biogenic U(IV) species as uraninite may be produced as result of bacterial enzymatic U(VI) reduction. These findings suggest that under electron donor-rich water-saturation conditions, bentonite microbial community can control U speciation, immobilizing it, and thus enhancing future DGR safety if container rupture and waste leakage occurs.
      Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
      (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)
    • Contributed Indexing:
      Keywords: Bentonite slurry; DGR; Long-term incubation; Microbial diversity; Sulfate-reducing bacteria; Uranium
    • Accession Number:
      1302-78-9 (Bentonite)
      4OC371KSTK (Uranium)
      0 (Radioactive Waste)
      0 (Water Pollutants, Radioactive)
    • Publication Date:
      Date Created: 20240629 Date Completed: 20240808 Latest Revision: 20240808
    • Publication Date:
      20240808
    • Accession Number:
      10.1016/j.jhazmat.2024.135044
    • Accession Number:
      38943881