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Journal Articles

Ecological and genomic profiling of anaerobic methane-oxidizing archaea in a deep granitic environment

Ino, Kohei*; Hernsdorf, A. W.*; Konno, Yuta*; Kozuka, Mariko*; Yanagawa, Katsunori*; Kato, Shingo*; Sunamura, Michinari*; Hirota, Akinari*; Togo, Yoko*; Ito, Kazumasa*; et al.

ISME Journal, 12(1), p.31 - 47, 2018/01

 Times Cited Count:30 Percentile:93.55(Ecology)

In this study, we found the dominance ofanaerobic methane-oxidizing archaea in groundwater enriched in sulfate and methane from a 300-m deep underground borehole in granitic rock.

Journal Articles

Deep microbial life in high-quality granitic groundwater from geochemically and geographically distinct underground boreholes

Ino, Kohei*; Konno, Yuta*; Kozuka, Mariko*; Hirota, Akinari*; Togo, Yoko*; Fukuda, Akari*; Komatsu, Daisuke*; Tsunogai, Urumu*; Tanabe, Akifumi*; Yamamoto, Satoshi*; et al.

Environmental Microbiology Reports (Internet), 8(2), p.285 - 294, 2016/04

 Times Cited Count:18 Percentile:67.66(Environmental Sciences)

To understand the subsurface biosphere, borehole investigation was conducted for 300-m deep granitic rocks at the Mizunami underground research laboratory, Japan. The initial biomass was the highest with the flourish of aerobic H$$_{2}$$-oxidizing Hydrogenophaga spp., whereas an uncultivated lineage of the phylum Nitrospirae became predominant after three years with decreasing biomass. The common occurrence of many species of Nitrospirae and Chlorobi phyla at the geographically distinct sites and the exclusive detection of their phylogenetically related environmental sequences from deep groundwaters and terrestrial hot springs, suggest that these bacteria are indigenous and potentially adapted to the deep terrestrial subsurface.

Journal Articles

Biogeochemical signals from deep microbial life in terrestrial crust

Suzuki, Yohei*; Konno, Yuta*; Fukuda, Akari*; Komatsu, Daisuke*; Hirota, Akinari*; Watanabe, Katsuaki*; Togo, Yoko*; Morikawa, Noritoshi*; Hagiwara, Hiroki; Aosai, Daisuke*; et al.

PLOS ONE (Internet), 9(12), p.e113063_1 - e113063_20, 2014/12

 Times Cited Count:9 Percentile:36.08(Multidisciplinary Sciences)

We present multi-isotopic evidence of microbially mediated sulfate reduction in a granitic aquifer, a representative of the terrestrial crust habitat. Deep groundwater of meteoric origin was collected from underground boreholes drilled into the Cretaceous Toki granite, central Japan. A large sulfur isotopic fractionation of 20-60 permil diagnostic to microbial sulfate reduction is associated with the investigated groundwater containing sulfate below 0.2 mM. In contrast, a small carbon isotopic fractionation ($$<$$ 30 permil) is not indicative of methanogenesis. Our results demonstrate that the deep biosphere in the terrestrial crust is metabolically active and playing a crucial role in the formation of reducing groundwater even under low energy fluxes.

Oral presentation

Response function measurement for 14 MeV neutrons by a CVD single diamond crystal synthesized with high-growth rate

Sato, Kei*; Kakimoto, Akinori*; Kaneko, Junichi*; Fujita, Fumiyuki*; Tsubouchi, Nobuteru*; Mokuno, Yoshiaki*; Chayahara, Akiyoshi*; Sato, Satoshi; Konno, Yuta*; Homma, Akira*; et al.

no journal, , 

As a part of development of diamond energy spectrometers using the $$^{12}$$C(n,$$alpha$$)$$^{9}$$Be reaction for DT plasma ion temperature measurement, response functions measurement of chemical vapor deposition (CVD) single crystal diamonds for alpha particles and 14 MeV neutrons were carried out. One diamond sample was synthesized by the national institute of advanced industrial science and technology (AIST) aiming at a large size and high-quality substrate for electric device with higher methane concentration of 10%. This diamond crystal was chosen according to intensity of free exciton recombination luminescence. In addition, a CVD single crystal diamond, categorized in "detector grade" synthesized by Element 6 Inc. was evaluated.Response function measurement of 14 MeV neutrons were carried out at the Fusion Neutronic Source facility of Japan Atomic Energy Agency. Energy resolutions of 4.3% and 5.2% for the $$^{12}$$C(n,$$alpha$$)$$^{9}$$Be reaction were obtained by the two CVD diamond single crystals. In general, energy spectrometer grade CVD diamond single crystals are grown using lower methane concentration, i.e., 1%. However, this results revealed that even higher methane concentration of 10% can grow energy spectrometer grade CVD diamond single crystals.

Oral presentation

Evaluation of CVD diamonds for a DT neutron energy spectrometer

Sato, Kei*; Kaneko, Junichi*; Fujita, Fumiyuki*; Kakimoto, Akinori*; Tsubouchi, Nobuteru*; Mokuno, Yoshiaki*; Chayahara, Akiyoshi*; Sato, Satoshi; Konno, Yuta*; Homma, Akira*; et al.

no journal, , 

As a part of development of diamond energy spectrometers using the $$^{12}$$C(n,$$alpha$$)$$^{9}$$Be reaction for DT plasma ion temperature measurement, response functions measurement of chemical vapor deposition (CVD) single crystal diamonds for alpha particles and 14 MeV neutrons were carried out. One diamond sample was synthesized by the national institute of advanced industrial science and technology (AIST) aiming at a large size and high-quality substrate for electric device with higher methane concentration of 10%. This diamond crystal was chosen according to intensity of free exciton recombination luminescence. In addition, a CVD single crystal diamond, categorized in "detector grade" synthesized by Element 6 Inc. was evaluated. Response function measurement of 14 MeV neutrons were carried out at the Fusion Neutronic Source facility of Japan Atomic Energy Agency. Energy resolutions of 4.3% and 5.2% for the $$^{12}$$C(n,$$alpha$$)$$^{9}$$Be reaction were obtained by the two CVD diamond single crystals. In general, energy spectrometer grade CVD diamond single crystals are grown using lower methane concentration, i.e., 1%. However, these results revealed that even higher methane concentration of 10% can grow energy spectrometer grade CVD diamond single crystals.

Oral presentation

Hydrogen and carbon isotope geochemistry of freshwater aquifers at the Mizunami Underground Research Laboratory; Implications for ongoing biogeochemical processes in granitic rocks

Konno, Yuta*; Fukuda, Akari; Kozuka, Mariko*; Komatsu, Daisuke*; Tsunogai, Urumu*; Aosai, Daisuke; Mizuno, Takashi; Suzuki, Yohei*

no journal, , 

Our knowledge of biogeochemical processes mediated in those associated with freshwater should be integrated. We collected the groundwater samples from 200 m to 1150 m depths below ground level at Mizunami Underground Research Laboratory located in central Japan. We measured the concentration and both hydrogen and carbon isotopic compositions of dissolved methane, total inorganic carbon (TIC) and molecular hydrogen. The origin of methane could be speculated to be not biogenic CO$$_{2}$$ reduction or acetate fermentation but thermogenic or abiogenic. In contrast, C1/C2+C3 ratios supported biogenic methane production. The 300 m deep samples were enriched in hydrogen and acetate and depleted in sulfate, which is characteristic of acetogenesis. From these results, it is suggested that the production of acetate rather than methane could be dominant biogeochemical processes in the reducing portions of freshwater aquifers in granitic rocks.

Oral presentation

JAEA/AIST collaborative research project; Development and evaluation of investigation methodology to quantify microbial influences on the deep hydrogeochemical properties

Fukuda, Akari; Mizuno, Takashi; Aosai, Daisuke; Hagiwara, Hiroki; Yamamoto, Yuhei; Shingu, Shinya; Ito, Kazumasa*; Suzuki, Yohei*; Kozuka, Mariko*; Konno, Yuta*

no journal, , 

no abstracts in English

Oral presentation

Metabolic rates of subsurface microorganisms in a hydrogeochemically characterized granitic aquifer system at the Mizunami Underground Research Laboratory (MIU) in Japan

Fukuda, Akari; Kozuka, Mariko*; Konno, Yuta*; Aosai, Daisuke; Hagiwara, Hiroki; Mizuno, Takashi; Suzuki, Yohei*

no journal, , 

To quantify microbial influences on the hydrogeochemistry of a 99-1169-m deep granitic aquifer system, we developed methodology for sensitive measurements of a variety of aerobic and anaerobic metabolic activities. Briefly, microbial cells were ca. 30-fold concentrated in groundwater by filtration to incubate with electron acceptors. Aerobic respiration was more than 400 umol/L/year at depths of 99 and 175 m and decreased with increasing depth down to 36 umol/L/year at a depth of 1169 m. Nitrate respiration increased from 99 to 308 m (4.3 to 37 umol/L/year) and decreased with increasing depth down to 0.20 umol/L/year. Sulfate respiration ranging from 1.4 to 3.2 umol/L/year was detected only at depths above 200 m. The depletion of O$$_{2}$$ and NO$$_{3}$$$$^{-}$$ and a gradual decrease in sulfate with increasing depth in the granitic aquifer could be attributed to microbial respirations at rates clarified in this study. Our research was partially founded by Nuclear and Industry Safety Agency.

Oral presentation

Shifts in microbial sulfate reduction to CO$$_{2}$$ reduction depending on groundwater flow characteristics in deep granitic aquifers

Konno, Yuta*; Komatsu, Daisuke*; Nishimura, Shusaku*; Fukuda, Akari; Aosai, Daisuke; Mizuno, Takashi; Nagao, Seiya*; Tsunogai, Urumu*; Suzuki, Yohei*

no journal, , 

no abstracts in English

Oral presentation

JAEA/AIST colaborative research project; Development and evaluation of investigation methodology to quantify microbial influences on the deep hydrogeochemical properties

Fukuda, Akari; Mizuno, Takashi; Aosai, Daisuke; Hagiwara, Hiroki; Yamamoto, Yuhei; Shingu, Shinya; Takeno, Naoto*; Suzuki, Yohei*; Konno, Yuta*; Kozuka, Mariko*

no journal, , 

no abstracts in English

Oral presentation

Biogeochemical investigation of deep granitic groundwater from Mizunami Underground Research Laboratory (MIU)

Fukuda, Akari; Kozuka, Mariko*; Konno, Yuta*; Aosai, Daisuke; Shingu, Shinya; Hagiwara, Hiroki; Mizuno, Takashi; Suzuki, Yohei*

no journal, , 

no abstracts in English

Oral presentation

Unveiling key players in the geological disposal environment

Suzuki, Yohei*; Fukuda, Akari; Konno, Yuta*; Kozuka, Mariko*; Hagiwara, Hiroki; Aosai, Daisuke; Takeno, Naoto*; Mizuno, Takashi

no journal, , 

Oral presentation

Characterization of dissolved organic matter in groundwater during laboratory incubation

Nishimura, Shusaku*; Suzuki, Yohei*; Fukuda, Akari; Konno, Yuta*; Shuin, Kuniko*; Nagao, Seiya*

no journal, , 

no abstracts in English

Oral presentation

Microbial sulfate reduction and sulfur isotope fractionations in deep groundwater at Mizunami Underground Research Laboratory

Hirota, Akinari*; Togo, Yoko*; Ito, Kazumasa*; Suzuki, Yohei*; Fukuda, Akari*; Konno, Yuta*; Tsunogai, Urumu*; Komatsu, Daiyu*; Nagao, Seiya*; Iwatsuki, Teruki

no journal, , 

Isotopic compositions of sulfate, sulfide ions were measured in deep groundwater of Mizunami URL to estimate microbial activity. The results show that relatively large isotopic fractionation between sulfate and sulfide by microbial reduction.

Oral presentation

A Benchmark test of ENDF/B-VIII$$beta$$4.1 with TOF experiments at OKTAVIAN

Isobe, Yuta*; Yoshida, Shigeo*; Konno, Chikara

no journal, , 

A benchmark test of ENDF/B-VIII$$beta$$4.1 being developed in US were carried out with Co and Cu experiments in the OKTAVIAN TOF experiments. For the comparison, ENDF/B-VII.1 and JENDL-4.0 were also used. As a result, it is found out that the analysis results with ENDF/B-VIII$$beta$$4.1 agreed the measured data better than those with the other nuclear data in the Co experiment, while they are in worse agreement with the measured data than those with the other nuclear data in the Cu experiment. It is also demonstrated that the differences between the analysis results with ENDF/B-VIII$$beta$$4.1 and ENDF/B-VII.1 come from the inelastic scattering data to continuum states in $$^{59}$$Co and all the inelastic scattering data in $$^{63}$$Cu and $$^{65}$$Cu.

Oral presentation

Study on prevention effect of radionuclides adsorbed on the surface of measurement containers

Konno, Yuta*; Maeyama, Takeshi*; Saegusa, Jun; Shinohara, Hirofumi*; Ota, Hiroshi*; Isogai, Keisuke*

no journal, , 

no abstracts in English

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