著者

Shinsuke Kawagucci Sanae Sakai Eiji Tasumi Miho Hirai Yoshihiro Takaki Takuro Nunoura Masafumi Saitoh Yuichiro Ueno Naohiro Yoshida Takazo Shibuya James Clifford Sample Tomoyo Okumura Ken Takai

出版者

Japanese Society of Microbial Ecology / Japanese Society of Soil Microbiology / Taiwan Society of Microbial Ecology / Japanese Society of Plant Microbe Interactions / Japanese Society for Extremophiles

雑誌

Microbes and Environments (ISSN:13426311)

巻号頁・発行日

vol.38, no.2, pp.ME22108, 2023 (Released:2023-06-16)

参考文献数

114

被引用文献数

1

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Post-mega-earthquake geochemical and microbiological properties in subseafloor sediments of the Japan Trench accretionary wedge were investigated using core samples from Hole C0019E, which was drilled down to 851‍ ‍m below seafloor (mbsf) at a water depth of 6,890 m. Methane was abundant throughout accretionary prism sediments; however, its concentration decreased close to the plate boundary decollement. Methane isotope systematics indicated a biogenic origin. The content of mole­cular hydrogen (H2) was low throughout core samples, but markedly increased at specific depths that were close to potential faults predicted by logging-while-drilling ana­lyses. Based on isotopic systematics, H2 appeared to have been abundantly produced via a low-temperature interaction between pore water and the fresh surface of crushed rock induced by earthquakes. Subseafloor microbial cell density remained constant at approximately 105‍ ‍cells‍ ‍mL–1. Amplicon sequences revealed that predominant members at the phylum level were common throughout the units tested, which also included members frequently found in anoxic subseafloor sediments. Metabolic potential assays using radioactive isotopes as tracers revealed homoacetogenic activity in H2-enriched core samples collected near the fault. Furthermore, homoacetogenic bacteria, including Acetobacterium carbinolicum, were isolated from similar samples. Therefore, post-earthquake subseafloor microbial communities in the Japan Trench accretionary prism appear to be episodically dominated by homoacetogenic populations and potentially function due to the earthquake-induced low-temperature generation of H2. These post-earthquake microbial communities may eventually return to the steady-state communities dominated by oligotrophic heterotrophs and hydrogenotrophic and methylotrophic methanogens that are dependent on refractory organic matter in the sediment.

著者

Sebastian Oscar Danielache Chisato Yoshikawa Mizuo Kajino Satoshi Itou Wataru Kakeya Naohiro Yoshida Yasuhito Igarashi

出版者

GEOCHEMICAL SOCIETY OF JAPAN

雑誌

GEOCHEMICAL JOURNAL (ISSN:00167002)

巻号頁・発行日

vol.53, no.2, pp.103-118, 2019 (Released:2019-04-05)

参考文献数

24

被引用文献数

1

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We present a numerical study conducted using a regional Lagrangian model to account for the transport, deposition and radioactive decay of 35S in sulfur dioxide and sulfate aerosols emitted into the atmosphere during the Fukushima Dai-ichi Nuclear Power Plant incident. The model is a Eulerian-Lagrangian hybrid system that accounts for chemical conversion of SO2 into SO42− in a Eulerian manner. The simulations were compared to field measurements of atmospheric 35S in sulfate collected at Kawamata, Tsukuba, Kashiwa, Fuchu and Yokohama, Japan. The 35S emission scenario that best replicated the field measurements followed the same temporal variation pattern as the 134/137Cs emissions. These results suggest that 35S and 134/137Cs follow a similar release pattern. Among the considered emission scenarios, a maximum flux of emitted chemical compounds was assumed to be either 100% 35SO42− or 100% 35SO2, with values of 4.0 × 1019 molecules/hour and 4.0 × 1020 molecules/hour, respectively on March 14th. These emission scenarios reflect the findings reported in the literature, where traces of 35SO2 were measured along with 35SO42−, so the actual emission is expected to be a combination of both chemical forms. The Kawamata measurements (Figs. 5 and 6) presented a large concentration in the July–August period, several months after emissions decreased by more than an order of magnitude. To explain this anomaly, re-suspension ratios were calculated for the Kawamata site, which ranged between 0.1 and 1.5% and partially, but not fully, explain the large measured concentrations. Furthermore, they show large discrepancies with 134/137Cs re-suspension values for measurements at the town of Namie. This situation indicates a lack of understanding of the transformations of 35S that occurs after deposition and the mechanisms involved in the 35S re-suspension process.