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Microbial influence in Spanish bentonite slurry microcosms: unveiling a-year long geochemical evolution and early-stage copper corrosion related to nuclear waste repositories

Marcos F. Martinez-Moreno, Cristina Povedano-Priego, Mar Morales-Hidalgo, Adam Mumford, Elisabet Aranda, Ramiro Vilchez-Vargas, Fadwa Jroundi, Jesus Ojeda Ledo Orcid Logo, Mohamed L. Merroun

Environmental Pollution

Swansea University Authors: Adam Mumford, Jesus Ojeda Ledo Orcid Logo

Abstract

Deep Geological Repository (DGR) concept consists of storing radioactive waste in metal canisters, surrounded by compacted bentonite, and placed into a geological formation. Here, bentonite slurry microcosms with copper canister, inoculated with bacterial consortium and amended with acetate, lactate...

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Published in: Environmental Pollution
Published: Elsevier
URI: https://cronfa.swan.ac.uk/Record/cronfa66919
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Abstract: Deep Geological Repository (DGR) concept consists of storing radioactive waste in metal canisters, surrounded by compacted bentonite, and placed into a geological formation. Here, bentonite slurry microcosms with copper canister, inoculated with bacterial consortium and amended with acetate, lactate and sulfate were set up to investigate their geochemical evolution over a year under anoxic conditions. The impact of microbial communities on the corrosion of copper canister in an early-stage (45 days) was also assessed. The amended bacterial consortium and electron donors/acceptor accelerated the microbial activity, while bentonite heat-shocked process had a retarding effect. The microbial communities partially oxidize lactate to acetate which is subsequently consumed when the lactate is depleted. Early-stage microbial communities showed that the bacterial consortium reduced microbial diversity with Pseudomonas and Stenotrophomonas dominating the community. However, sulfate-reducing bacteria such as Desulfocurvibacter, Anaerosolibacter, and Desulfosporosinus were enriched coupling oxidation of lactate/acetate with reduction of sulfates. The generated biogenic sulfides could mediate the conversion of copper oxides (possibly formed by trapped oxygen molecules on the bentonite or driven by the reduction of H2O) to copper sulfide (Cu2S) identified by X-ray photoelectron spectroscopy (XPS). Overall, these findings shed light on the ideal geochemical conditions that would affect the stability of DGR barriers, emphasizing the impact of the SRB on the corrosion of the metal canisters, the gas generation, and the interaction with components of the bentonite.
College: Faculty of Science and Engineering
Funders: The present work was supported by the grant RTI2018–101548-B-I00 “ERDF A way of making Europe” to MLM from the “Ministerio de Ciencia, Innovación y Universidades” (Spanish Government). The project leading to this application has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement No 847593 to MLM. ADM acknowledges funding from the UK Engineering and Physical Sciences Research Council (EPSRC) DTP scholarship (project reference: 2748843).