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Ise, Kotaro; Sasaki, Yoshito; Amano, Yuki; Iwatsuki, Teruki; Nanjo, Isao*; Asano, Takahiro*; Yoshikawa, Hideki
Geomicrobiology Journal, 34(6), p.489 - 499, 2017/07
Times Cited Count:4 Percentile:14.31(Environmental Sciences)We investigated the change in bacterial community structure after drilling boreholes, 09-V250-M02 and 09-V250-M03 in the 250 m depth research gallery of Horonobe Underground Research Laboratory (URL). In 09-V250-M02, -Proteobacteria was predominantly detected in the clone library analyses of the groundwater samples conducted immediately after drilling the borehole. All these -Proteobacteria clones are closely related to . which is known as sulfide oxidizing chemoautotrophic bacteria. After four years, the microbial structure was drastically changed and most detected OTUs were uncultured species such as candidate division OP9 and Chloroflexi relatives which are frequently detected in deep-sea sediments.
Katsuyama, Chie*; Nashimoto, Hiroaki*; Nagaosa, Kazuyo*; Ishibashi, Tomotaka*; Furuta, Kazuki*; Kinoshita, Takeshi*; Yoshikawa, Hideki; Aoki, Kazuhiro; Asano, Takahiro*; Sasaki, Yoshito; et al.
FEMS Microbiology Ecology, 86(3), p.532 - 543, 2013/12
Times Cited Count:14 Percentile:36.94(Microbiology)Anaerobic microbial activity has a major influence on the subsurface environment, and should be considered in subsurface activities including the construction of radioactive waste repositories. We investigated denitrification and methanogenesis in anoxic groundwater from 140 m depth in two boreholes, where the redox potential fluctuated. The average maximum potential denitrification rates, measured under anaerobic conditions in the two boreholes using an N tracer. Methanogenesis candidates were detected by 16S rRNA gene analysis. Although the stable isotope signatures suggested that some of the dissolved methane was of biogenic origin, no potential for methane production was evident during the incubations. The groundwater at 140 m depth did not contain oxygen, had an Eh ranging from -144 to 6.8 mV, and was found to be a potential field for denitrification.
Yoshikawa, Hideki; Kawakita, Masakazu*; Fujiwara, Kazuhiro*; Sato, Tomofumi; Asano, Takahiro*; Sasaki, Yoshito
Materials Research Society Symposium Proceedings, Vol.1475, p.617 - 622, 2012/06
Since it was suggested that the microbes have ability to generate their biofilm in deep underground condition, we examined the effects of biofilm on radionuclide migration scenario. To estimate the effect on matrix diffusion, through diffusion experiment for a biofilm of Desulfovivrio desullfuricans were performed. The effective diffusion coefficient of the biofilm was 10 m/s order which was about ten times smaller than that in free water. It is suggesting that the microbes and biofilm will not interfere with matrix diffusion as a retardation of radionuclide in rock.
Tochigi, Yoshikatsu; Yoshikawa, Hideki; Aoki, Kazuhiro; Yui, Mikazu; Asano, Takahiro*; Honjo, Hideko*; Haginuma, Masashi*; Kawakami, Yasushi*; Suzuki, Kazunori*
JAEA-Research 2008-025, 55 Pages, 2008/03
Results of joint research on fiscal year 2006 between Japan Atomic Energy Agency (JAEA) and Institute of Research and Innovative (IRI) titled as "Study on investigation of microbial effects for geological disposal" are described in this report. The objective of this study is to develop a method for estimating microbial effects for barrier performance of geological disposal site. The modeling was performed to examine the effect on the change in groundwater chemistry (mainly by electron acceptors) by microbial metabolism as well as microbial activities. In order to use the data (chemical composition, biomass, etc.) in the MINT code, groundwater was collected from the drilled well prepared for chemical and microbial analyses of groundwater. The well was prepared in observation field near Horonobe Underground Research Center of JAEA in fiscal year 2006. Then, numerical modeling using collected data of groundwater with numerical modeling program code "MINT" considering microbial effects was carried out. The modeling was carried out to evaluate the microbial effect for stability of chemical and microbial composition of groundwater. As the result of the modeling, relatively low microbial effect for groundwater composition was observed in particular for the concentration of dissolved methane, methanogen, sulfur reducing bacteria (SRB) and sulfur ion. The result shows that low redox potential is stable in the well in spite of shallow depth.
Asano, Takahiro; Ishii, Kosuke*; Miyasaka, Iku*; Sasaki, Yoshito; Yoshikawa, Hideki; Yui, Mikazu
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Sasaki, Yoshito; Asano, Takahiro; Iwatsuki, Teruki; Yoshikawa, Hideki; Yui, Mikazu
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Asano, Takahiro; Sasaki, Yoshito; Nagaosa, Kazuyo*; Kato, Kenji*; Yoshikawa, Hideki
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Fukunaga, Sakae*; Ishii, Kosuke*; Miyasaka, Iku*; Asano, Takahiro; Sasaki, Yoshito; Yoshikawa, Hideki
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Yoshikawa, Hideki; Asano, Takahiro; Sasaki, Yoshito; Yui, Mikazu; Miyasaka, Iku*
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To evaluation of safety assessment for high-level radioactive waste disposal, it is considered that microbial effect is very important. The effects of microbes on groundwater chemistry is evaluated with the numerical code "MINT", using data collected from the borehole HDB-10 in the Horonobe underground research laboratory (URL) in Japan.
Iwatsuki, Teruki; Yoshikawa, Hideki; Asano, Takahiro; Sasaki, Yoshito
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Feature, event and process (FEP) on water-rock-microbe system were analyzed to understand the long-term evolution of geochemical system in deep underground at Horonobe area, Hokkaido Japan. The chemical and isotopic signatures recorded on secondary precipitation minerals, groundwater, dissolved gases suggest that the microbial reduction process in early diagenesis after sedimentation of rock formation controlls groundwater chemistry.
Fukunaga, Sakae*; Ishii, Kosuke*; Miyasaka, Iku*; Asano, Takahiro; Sasaki, Yoshito; Yoshikawa, Hideki
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Ishii, Kosuke*; Miyasaka, Iku*; Fukunaga, Sakae*; Asano, Takahiro; Sasaki, Yoshito; Yoshikawa, Hideki
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Nagaosa, Kazuyo*; Asano, Takahiro; Sasaki, Yoshito; Yoshikawa, Hideki; Kato, Kenji*
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Asano, Takahiro; Sasaki, Yoshito; Kageyama, Koji*; Yoshikawa, Hideki
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Asano, Takahiro; Sasaki, Yoshito; Yoshikawa, Hideki
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On deep geological environment, microbes affect the changes in the redox of groundwater which is one of the most important properties to estimate the condition of a geological disposal system. It is necessary to quantify microbial biomass on the geological environment as input data in numerical model to evaluate the redox condition. We estimated microbial biomass related to microgeochemical processes in goundwater using real-time PCR. The groundwater was obtained from the Horonobe borehole H17-1-01 (-35m depth) and HDB-10 (-500m depth). The dominant members of microbes at H17-1-01 were Mn(IV)- and Fe(III)-reducers and sulphate reducers. On the other hand, the dominant members of microbes at HDB-10 were sulphate reducers and methanogens. The results of real-time PCR assay showed the same tendency on the results of the cultivation-based methods and 16S-rRNA clone analysis. This result suggests that the real-time PCR will be useful for quantification of microbial biomass on the geological environment.
Sena, C.*; Molinero, J.*; Nagaoka, Toru*; Ajima, Shuji*; Ito, Tsuyoshi; Sasaki, Yoshito; Asano, Takahiro; Yoshikawa, Hideki
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Sasaki, Yoshito; Ito, Tsuyoshi; Asano, Takahiro; Yoshikawa, Hideki
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Kato, Kenji*; Nagaosa, Kazuyo*; Tsunogai, Urumu*; Asano, Takahiro; Sasaki, Yoshito; Yoshikawa, Hideki
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Yoshikawa, Hideki; Sasaki, Yoshito; Asano, Takahiro; Ito, Tsuyoshi; Yui, Mikazu
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Ishibashi, Tomotaka*; Nagaosa, Kazuyo*; Katsuyama, Chie*; Nashimoto, Hiroaki*; Asano, Takahiro; Sasaki, Yoshito; Iwatsuki, Teruki; Yoshikawa, Hideki; Kato, Kenji*
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