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Dual effect of Se(IV) and bentonite microbial community interactions on the corrosion of copper and Se speciation: Implication on repository safety assessment
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Fadwa Jroundi,
Jesus Ojeda Ledo ,
Mohamed L. Merroun
Science of The Total Environment, Volume: 965, Start page: 178613
Swansea University Authors:
Adam Mumford, Yon Ju-Nam , Jesus Ojeda Ledo
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DOI (Published version): 10.1016/j.scitotenv.2025.178613
Abstract
Deep Geological Repository design, the internationally safest option for the long term disposal of high-level radioactive waste (HLW), features metal canisters encased in compacted bentonite clay and embedded deep within a host rock. Despite presenting a hostile environment for microorganisms, DGRs...
| Published in: | Science of The Total Environment |
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| ISSN: | 0048-9697 |
| Published: |
Elsevier BV
2025
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| Online Access: |
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| URI: | https://cronfa.swan.ac.uk/Record/cronfa68712 |
| Abstract: |
Deep Geological Repository design, the internationally safest option for the long term disposal of high-level radioactive waste (HLW), features metal canisters encased in compacted bentonite clay and embedded deep within a host rock. Despite presenting a hostile environment for microorganisms, DGRs scenarios with favorable microbial activity conditions must be considered for the safety assessment of this disposal. This study investigated the impact of Se(IV), as a natural analogue of 79Se present in the HLW, in anoxic microcosms of bentonite slurry spiked with a bacterial consortium and amended with lactate, acetate, and sulfate as electron donors/acceptor. The addition of the bacterial consortium promoted the rate of Se(IV) reduction to Se(0), while the tyndallization (heat shock) of bentonite slowed this process. Se(IV) reduced the relative abundance of most genera of sulfate-reducing bacteria (SRB), while stimulating the abundance of Se-tolerant bacteria, which played an important role in Se(IV) reduction. Moreover, it was observed that lactate was the preferred electron donor, linking with the production, and subsequent consumption of acetate. X-ray absorption spectroscopy (XAS) and high-resolution transmission electron microscopy (HRTEM) revealed the reduction of Se(IV) forming amorphous Se(0) nanospheres. In addition, HRTEM showed that the biogenic Se(0) undergo a biotransformation to more stable crystalline forms, contributing to the immobilization of Se in the case of HLW release. Additionally, the sulfide generated by the activity of SRB reacted with Cu producing corrosion products (CuxS) on the surface of the copper material. |
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| Keywords: |
Deep geological repository; Selenium speciation; Bentonite; Bacteria; Copper biocorrosion |
| 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 programme 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). |
| Start Page: |
178613 |