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Miyakawa, Kazuya; Ishii, Eiichi; Imai, Hisashi*; Hirai, Satoru*; Ono, Hirokazu; Nakata, Kotaro*; Hasegawa, Takuma*
Genshiryoku Bakkuendo Kenkyu (CD-ROM), 31(2), p.82 - 95, 2024/12
no abstracts in English
sp. strain V2501 isolated from 250 m below the ground level in Horonobe, Hokkaido, JapanUeno, Akio*; Sato, Kiyoshi*; Tamamura, Shuji*; Murakami, Takuma*; Inomata, Hidenori*; Tamazawa, Satoshi*; Amano, Yuki; Miyakawa, Kazuya; Naganuma, Takeshi*; Igarashi, Toshifumi*
Microbiology Resource Announcements (Internet), 13(11), p.e00108-24_1 - e00108-24_4, 2024/11
Hirota, Akinari*; Kozuka, Mariko*; Fukuda, Akari*; Miyakawa, Kazuya; Sakuma, Keisuke; Ozaki, Yusuke; Ishii, Eiichi; Suzuki, Yohei*
Microbial Ecology, 87, p.132_1 - 132_15, 2024/10
Times Cited Count：0 Percentile：0.00(Ecology)Deep underground galleries are used to access the deep biosphere in addition to mining and other engineering applications such as geological disposal of radioactive wastes. Fracture networks developed in the excavation damaged zone (EDZ) are concerned to accelerate mass transport, where microbial colonization might be possible due to the availability of space and nutrients. In this study, microbial biofilms at EDZ fractures were investigated by drilling from a 350-m deep gallery and subsequent borehole logging at the Horonobe underground research laboratory (URL). By using microscopic and spectroscopic techniques, the dense colonization of microbial cells was demonstrated at the surfaces of the EDZ fractures with high hydraulic conductivities. 16S rRNA gene sequence analysis revealed the dominance of gammaproteobacterial lineages, the cultivated members of which are aerobic methanotrophs. Near-complete Horonobe groundwater genomes affiliated within the methanotrophic lineages were fully equipped with genes involved in aerobic methanotrophy. Although the mediation of aerobic methanotrophy remains to be demonstrated, microbial O
production was supported by the presence of genes in the near-complete genomes, such as catalase and superoxide dismutase that produce O from reactive oxygen species and a nitric oxide reductase gene with the substitutions of amino acids in motifs. It is concluded that the EDZ fractures provide energetically favorable subsurface habitats to microorganisms.
Saito, Takumi*; Nishi, Shusaku*; Amano, Yuki; Beppu, Hikari*; Miyakawa, Kazuya
ACS ES&T Water (Internet), 3(12), p.4103 - 4112, 2023/12
Miyakawa, Kazuya; Hayano, Akira; Sato, Naomi; Nakata, Kotaro*; Hasegawa, Takuma*
JAEA-Data/Code 2023-009, 103 Pages, 2023/09
JAEA-Data-Code-2023-009.pdf:9.29MB
JAEA-Data-Code-2023-009-appendix1(DVD-ROM).zip:271.51MBJAEA-Data-Code-2023-009-appendix2(DVD-ROM).zip:883.78MBJAEA-Data-Code-2023-009-appendix3(DVD-ROM).zip:10.29MB
This borehole investigation was carried out to confirm the validity of the distribution of low flow areas deep underground estimated based on the geophysical survey in FY 2020, as a part of an R&D supporting program titled "Research and development on Groundwater Flow Evaluation Technology in Bedrock" under contract to the Ministry of Economy, Trade and Industry (2021, 2022 FY, Grant Number: JPJ007597). The borehole name is Horonobe Fossil seawater Boring-1 and is referred to as HFB-1 borehole. HFB-1 is a vertical borehole drilled adjacent to the Horonobe Underground Research Laboratory (URL), which was drilled from the surface to a depth of 200 m in FY2021 and from a depth of 200 m to 500 m in FY2022. This report summarizes information related to the drilling of HFB-1 and various data (rock core description, geophysical logging, chemical analysis, etc.) obtained from the borehole investigation.
MethanoperedenaceaeNishimura, Hiroki*; Kozuka, Mariko*; Fukuda, Akari*; Ishimura, Toyoho*; Amano, Yuki; Beppu, Hikari*; Miyakawa, Kazuya; Suzuki, Yohei*
Environmental Microbiology Reports (Internet), 15(3), p.197 - 205, 2023/06
Times Cited Count：1 Percentile：21.41(Environmental Sciences)The family Methanoperedenaceae archaea mediate anaerobic oxidation of methane (AOM). We newly developed a high-pressure laboratory incubation system and investigated groundwater from 214- and 249-m deep boreholes at Horonobe Underground Research Laboratory, Japan, where the high and low abundances of Methanoperedenaceae archaea have been revealed, respectively. We incubated the samples amended with or without amorphous Fe(III) and 
C-labelled methane at an in-situ pressure of 1.6 MPa. After three to seven-day incubation, AOM activities were not detected from the 249-m sample but from the 214-m sample. The AOM rates were 93.7
40.6 and 27.737.5 nM/day with and without Fe(III) amendment. Suspended particulates were not visible in the 249-m sample on the filter, while they were abundant and contained amorphous Fe(III) and Fe(III)-bearing phyllosilicates in the 214-m sample. This supports the in-situ activity of Fe(III)-dependent AOM in the deep subsurface borehole.
Miyakawa, Kazuya; Nakata, Kotaro*
JAEA-Data/Code 2022-013, 19 Pages, 2023/03
JAEA-Data-Code-2022-013.pdf:1.88MB
In the Horonobe Underground Research Laboratory (URL) project, groundwater chemistry was analyzed to investigate changes due to the excavation of the underground facility and to review geochemical models until the fiscal year 2019. From the fiscal year 2020, to proceed remaining important issues deduced from the conclusion of the investigations during the fiscal year 2015-2019, primary data such as groundwater chemistry need to be successively acquired. Here, the chemical analysis of 54 groundwater samples in 2022 from boreholes drilled in the 140 m, 250 m, 350 m gallery in the Horonobe URL, and water rings settled in three vertical shafts is presented. Analytical results include groundwater chemistry such as pH, electrical conductivity, dissolved components (Na
, K, Ca
, Mg, Li, NH
, F
, Cl, Br, NO
, NO
, PO
, SO
, Total-Mn, Total-Fe, Al, B, Sr, Ba, I, alkalinity, dissolved organic carbon, dissolved inorganic carbon, CO, HCO, Fe, sulfide), and 
O, D along with a detailed description of analytical methods.
Miyakawa, Kazuya; Kashiwaya, Koki*; Komura, Yuto*; Nakata, Kotaro*
Geochemical Journal, 57(5), p.155 - 175, 2023/00
Times Cited Count：1 Percentile：24.61(Geochemistry & Geophysics)In the thick marine sediments, groundwater altered from seawater during the burial diagenesis may exist. Such altered ancient seawater will be called fossil seawater. In such a field, groundwater flow is considered extremely slow because it is not affected by the seepage of meteoric water even after the uplift. During diagenesis, dehydration from silicates causes changes such as a decrease in the salinity of the porewater. However, dehydration reactions alone cannot quantitatively explain water chemistry changes. In this study, we developed an analytical model that considers the dehydration reaction from silicates during the burial process and the upward migration of porewater due to compaction and examined the possible evolution of porewater chemistry. The results showed that the water chemistry, which was strongly influenced by the dehydration reaction from opal-A to quartz and from smectite, was similar to the observations from boring surveys. The results suggest that the fossil seawater formed during the diagenesis may have been preserved since the uplift and strongly supports the slow groundwater flow in the area where the fossil seawater exists.
Miyakawa, Kazuya; Yamamoto, Hajime*
JAEA-Research 2022-003, 40 Pages, 2022/05
JAEA-Research-2022-003.pdf:6.08MB
The excavation of large-scale underground facilities, such as geological disposal of high-level radioactive waste, creates an excavation damaged zone (EDZ) with cracks around the tunnel. In the EDZ, oxygen invades the bedrock through unsaturated cracks and affects environmental conditions for nuclide migration. When a tunnel is excavated in a geological formation containing a high concentration of dissolved CH, such as the Neogene marine sediments, degassed CH prevents oxygen intrusion. However, it may be promoted through gas-phase diffusion through desaturation. The purpose of this study is to illustrate the method of estimating the spatial distribution of desaturation associated with the construction and operation of underground facilities in a stratum that contains a large amount of dissolved CH. A sequential excavation analysis that reflected the actual process of 10-year excavation of the Horonobe Underground Research Laboratory (URL) was carried out along with gas-water two-phase flow analysis. The analysis results of the amount of groundwater and gas discharged from the URL were about 100 to 300 m
d
and 250 to 350 m d, respectively, as of January 2017. These results showed values close to the observations (100 m d and 300 m d, respectively). The analysis results of the saturation distribution were relatively high around the 250 m gallery and relatively low around the 350 m gallery, confirming that they are consistent with the in-situ observations. Although there were still technical issues of analysis regarding the conditions for groundwater drainage from the tunnel wall and the method of handling grout effects, the numerical calculation was generally appropriate. Although the results of the saturation distribution associated with the excavation were insufficient as the quantitative evaluation, they were almost correct from a qualitative point of view.
Kirishima, Akira*; Terasaki, Mariko*; Miyakawa, Kazuya; Okamoto, Yoshihiro; Akiyama, Daisuke*
Chemosphere, 289, p.133181_1 - 133181_12, 2022/04
Times Cited Count：1 Percentile：4.10(Environmental Sciences)no abstracts in English
and Eu
ions onto sedimentary rock in the presence of gamma-irradiated humic acidZhao, Q.*; Saito, Takeshi*; Miyakawa, Kazuya; Sasamoto, Hiroshi; Kobayashi, Taishi*; Sasaki, Takayuki*
Journal of Hazardous Materials, 428, p.128211_1 - 128211_10, 2022/04
Times Cited Count：6 Percentile：49.04(Engineering, Environmental)The influence of humic acid and its radiological degradation on the sorption of Cs and Eu by sedimentary rock was investigated to understand the sorption process of metal ions and humic substances. Aldrich humic acid (HA) solution was irradiated with different doses of gamma irradiation using a Co-60 gamma-ray source prior to the contact between the metal ions and the solid sorbent. The HA molecule decomposed to smaller molecules with a lower complexation affinity. Batch sorption experiments were performed to evaluate the effect of gamma-irradiated HA on the sorption of Cs and Eu ions. The addition of non-irradiated HA weakened the sorption of Eu because of the lower sorption of the neutral or negatively charged Eu-HA complexes compared with free Eu ions. The sorption of monovalent Cs ions was barely affected by the presence of HA and its gamma irradiation. The concentration ratio of HA complexed species and non-complexed species in the solid and liquid phases was evaluated by sequential filtration and chemical equilibrium calculations. The ratios supported the minimal contribution of HA to Cs sorption. However, the concentration ratio for Eu in the liquid phase was high, indicating that the complexing ability of HA to Eu was higher than that of HA to Cs ions. Therefore, the sorption of free Eu would predominate with the gamma irradiation dose applied to the HA solution under a radiation field near the HLW package.
Miyakawa, Kazuya
JAEA-Data/Code 2021-021, 23 Pages, 2022/03
JAEA-Data-Code-2021-021.pdf:2.0MB
In the Horonobe underground research laboratory (HURL) project, groundwater chemistry was analyzed to investigate changes due to the excavation of the underground facility and to review geochemical models until the fiscal year 2019. From the fiscal year 2020, to proceed remaining important issues deduced from the conclusion of the investigations during the fiscal year 2015-2019, primary data such as groundwater chemistry need to be successively acquired. Here, the chemical analysis of 54 groundwater samples in 2021 from boreholes drilled in the 140 m, 250 m, 350 m gallery in the HURL, and water rings settled in three vertical shafts is presented. Analytical results include groundwater chemistry such as physicochemical parameters (pH, electrical conductivity), dissolved ions (Na, K, Li, NH, Cl, Br, NO, SO, PO, Ca, Mg, Sr, P, Total-Mn, Si, Total-Fe, Al, B, F, I, alkalinity, total organic carbon, total inorganic carbon, CO, HCO, Ba, Fe, sulfide), O, D, and tritium content along with a detailed description of analytical methods.
Shimo, Michito*; Niwa, Masakazu; Miyakawa, Kazuya; Yasue, Kenichi*; Tonokura, Kenichi*; Tokunaga, Tomochika*
Fukada Chishitsu Kenkyujo Nempo, (23), p.21 - 34, 2022/00
no abstracts in English
Dei, Shuntaro; Mochizuki, Akihito; Miyakawa, Kazuya; Sasamoto, Hiroshi
JAEA-Data/Code 2021-005, 54 Pages, 2021/06
JAEA-Data-Code-2021-005.pdf:4.95MBJAEA-Data-Code-2021-005-appendix(CD-ROM).zip:5.42MB
Japan Atomic Energy Agency had been conducting "geoscientific study" and "research and development on geological disposal" in the Horonobe Underground Research Laboratory (URL) for safe geological disposal of high-level radioactive waste. Groundwater pressure, pH, and oxidation-reduction potential in the deep groundwater have been continuously monitored with monitoring systems which were developed in the Horonobe URL Project. This report presents the physicochemical parameters of groundwater which have been obtained by the monitoring systems installed at the 140 m, 250 m and 350 m gallery. The data acquired from April 2017 to the end of March 2020 was summarized along with related information such as the specifications of boreholes.
Miyakawa, Kazuya
JAEA-Data/Code 2021-003, 25 Pages, 2021/05
JAEA-Data-Code-2021-003.pdf:1.91MB
Development of technologies to investigate properties of deep geological environment and model development of geological environment have been pursued in "Geoscientific Research" in the Horonobe Underground Research Laboratory (HURL) project. In the fiscal year 2020, to proceed remaining important issues which were deduced from the conclusion of the investigations during the fiscal year 2015-2019, basic data such as groundwater chemistry need to be successively acquired. In the fiscal year 2020, groundwater was sampled from boreholes drilled in the 140 m, 250 m, 350 m gallery in the HURL, and water rings settled in three each vertical shaft, and groundwater chemistries of 41 samples were analyzed. Here, analytical results of groundwater chemistry such as physicochemical parameters, dissolved ions, oxygen and hydrogen isotope ratios, and tritium content, which were obtained in the fiscal year 2020, were reported along with a detailed description of analytical methods.
Miyakawa, Kazuya; Aoyagi, Kazuhei; Akaki, Toshifumi*; Yamamoto, Hajime*
JAEA-Data/Code 2021-002, 26 Pages, 2021/05
JAEA-Data-Code-2021-002.pdf:2.14MBJAEA-Data-Code-2021-002-appendix(CD-ROM).zip:40.99MB
Investigations employing numerical simulation have been conducted to study the mechanisms of desaturation and oxygen infusion into sedimentary formations. By mimicking the conditions of the Horonobe underground research laboratory, numerical simulations aided geoscientific investigation of the effects of dissolved gas content and rock permeability on the desaturation (Miyakawa et al., 2019) and mechanisms of oxygen intrusion into the host rock (Miyakawa et al., 2021). These simulations calculated multi-phase flow, including flows of groundwater and exsolved gas, and conducted sensitivity analysis changing the dissolved gas content, rock permeability, and humidity at the gallery wall. Only the most important results from these simulations have been reported previously, because of publishers' space limitations. Hence, in order to provide basic data for understanding the mechanisms of desaturation and oxygen infusion into rock, all data for 27 output parameters (e.g., advective fluxes of heat, gas, and water, diffusive fluxes of water, CH, CO, O, and N, saturation degree, water pressure, and mass fraction of each component) over a modeling period of 100 years are presented here.
sp. nov., a mesophilic sulfate-reducing deltaproteobacterium isolated from a deep siliceous mudstone formationUeno, Akio*; Tamazawa, Satoshi*; Tamamura, Shuji*; Murakami, Takuma*; Kiyama, Tamotsu*; Inomata, Hidenori*; Amano, Yuki; Miyakawa, Kazuya; Tamaki, Hideyuki*; Naganuma, Takeshi*; et al.
International Journal of Systematic and Evolutionary Microbiology, 71(2), p.004683_1 - 004683_10, 2021/02
Times Cited Count：10 Percentile：54.37(Microbiology)A novel mesophilic sulfate-reducing bacterium, designated strain HN2
, was isolated from groundwater sampled from the subsurface Miocene Wakkanai Formation located in Horonobe, Hokkaido, Japan. The cells were Gram-negative rods, with motility conferred by a single polar flagellum. The isolate expressed desulfoviridin, but no catalase or oxidase activities was detected. Strain HN2 grew in a temperature range of 5-43 
C (optimum, 35 C) and in a pH range of 6.5-7.5 (optimum, pH 7.0-7.3). It used sulfate, thiosulfate, dimethyl sulfoxide, anthraquinone-2,6-disulfonate, Fe, and manganese oxide as electron acceptors, but not elemental sulfur, nitrite, or nitrate. The bacterium showed very weak growth with sulfite as the electron acceptor. The strain fermented pyruvate and cysteine in the absence of sulfate, but not malate or succinate. The bacterium did not require NaCl, but tolerated up to 4% NaCl (w/v). Strain HN2 did not require vitamins. The G+C content of the genomic DNA was 56.66 mol%. A 16S rRNA gene sequence analysis showed that the closest recognized relative of strain HN2 is 
JS1 (97.0% similarity). The average nucleotide identity (ANI) value between strain HN2 and D. 
JS1 was 79.8%. Based on the phenotypic and molecular genetic evidence, the isolate is assigned to the new species sp. nov. The type strain is HN2 (=DSM 101010 =NBRC 112213).
Miyakawa, Kazuya; Aoyagi, Kazuhei; Akaki, Toshifumi*; Yamamoto, Hajime*
Dai-15-Kai Iwa No Rikigaku Kokunai Shimpojiumu Koen Rombunshu (Internet), p.609 - 614, 2021/01
Desaturation is expected due to excavation of an underground repository, especially in the newly created fractures zone (EDZ). During the construction and operation of facilities, the air in the gallery infuses into the rock around the gallery though the excavation affected area and causes oxidation of host rock and groundwater, which increase nuclide mobilities. In the Horonobe underground research laboratory (HURL), which is excavated in the Neogene sedimentary formations, no pyrite dissolution or precipitation of calcium sulfates was found from the cores drilled in the rock around the gallery. The reason for no oxidation is estimated that the release of dissolved gases from groundwater due to pressure decrease flows against the air infusion. In this research, the mechanism of O intrusion into the rock was investigated by numerical multiphase flow simulation considering advection and diffusion of groundwater and gases. In the simulation, only Darcy's and Henry's laws were considered, that is, chemical reaction related to oxidation was not handled. The effects of dissolved gas and rock permeability on O infusion into the rock were almost identical. Decreasing humidity with relatively low permeability leads to extensive accumulation of O into the EDZ even though with a relatively large amount of dissolved gas. In the HURL, the shotcrete attenuates O concentration and keeps 100% humidity at the boundary of the gallery wall, which inhibits O infusion. Without the shotcrete, humidity at the gallery wall decreases according to seasonal changes and ventilation, which promotes O intrusion into the EDZ but the chemical reaction related to O buffering such as pyrite oxidation consumes O.
Miyakawa, Kazuya; Shimo, Michito*; Niwa, Masakazu; Amano, Kenji; Tokunaga, Tomochika*; Tonokura, Kenichi*
Fukada Chishitsu Kenkyujo Nempo, (22), p.139 - 153, 2021/00
no abstracts in English
Shimo, Michito*; Niwa, Masakazu; Miyakawa, Kazuya; Amano, Kenji; Tonokura, Kenichi*; Tokunaga, Tomochika*
Fukada Chishitsu Kenkyujo Nempo, (22), p.119 - 137, 2021/00
no abstracts in English
