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Friend or Foe? Microbial impact of Calcigel bentonite on metal materials used for nuclear waste repository

Authors :
(0000-0003-3783-6429) Wei, T.-S.
Sushko, V.
(0000-0001-5038-0273) Matschiavelli, N.
Kluge, S.
(0000-0002-3908-2539) Cherkouk, A.
(0000-0003-3783-6429) Wei, T.-S.
Sushko, V.
(0000-0001-5038-0273) Matschiavelli, N.
Kluge, S.
(0000-0002-3908-2539) Cherkouk, A.
Source :
2nd Joint Symposium of the International Societies for Environmental Biogeochemistry & Subsurface Microbiology 2023, 22.-28.10.2023, Banff, Canada
Publication Year :
2023

Abstract

Multi-barrier concept is a favorable option to store high-level nuclear waste (HLW) in a deep geological repository. Bentonites are processed clay materials that are considered as a geotechnical barrier for metal containers storing HLW. To understand the impact of indigenous microorganisms from bentonites on these metal materials, anaerobic microcosms incubating Calcigel bentonite, synthetic Opalinus clay (OPA) porewater, lactate (one of the organic acids in natural OPA porewater) or H2 gas (product from anaerobic metal corrosion) with or without cast iron metal plates were conducted for up to 9 months in triplicates for each condition and time point (sampling every 3 months). The amplicon sequencing targeting V4 region of 16S rRNA genes showed that microbial communities of raw Calcigel bentonites mainly comprised phyla Acidobacteria, Actinobacteria, Chloroflexi, Firmicutes, Proteobacteria and Methylomirabilota. In the microcosms with lactate, enrichment of Bacillaceae (Firmicutes) and uncultured MB-A2-108 (Actinobacteriota) were observed; whereas in the presence of both lactate and cast iron, genera of Firmicutes, namely Desulfotomaculum, Desulfitobacterium and Desulfallas-Sporotomaculum, were highly enriched (relative abundance ranged from 60% to 95%) associating with large decrease in sulfate and lactate concentration. These bacteria appeared to be driven by H2 gas generated from metal corrosion. Moreover, SEM-EDX analyses showed that the metal surface was corroded and covered by a carbonate passivation layer. In this layer, FeS appeared to be formed, further suggesting the influence on cast iron corrosion and formation of secondary minerals induced by sulfate-reducing bacteria. On the other hand, we supplied N2 gas mixed with H2 and CO2 (80:10:10) to stimulate growth of H2-oxidizing sulfate reducers. GC analyses showed that in the microcosms without cast iron, the content of H2 gas in the headspace decreased accompanying with decrease in sulfate concentration (m

Details

Database :
OAIster
Journal :
2nd Joint Symposium of the International Societies for Environmental Biogeochemistry & Subsurface Microbiology 2023, 22.-28.10.2023, Banff, Canada
Notes :
application/pdf, English
Publication Type :
Electronic Resource
Accession number :
edsoai.on1415607724
Document Type :
Electronic Resource