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Niizato, Tadafumi; Sasaki, Yoshito; Watanabe, Takayoshi; Amamiya, Hiroki*
Dai-31-Kai Shakai Chishitsugaku Shimpojiumu Rombunshu, p.19 - 22, 2021/11
A three-year monitoring of 
Cs outflow associated with soil erosion from decontaminated and burnt sites using an experimental plot was conducted in a mountainous forest of Fukushima, Japan. Corresponding with recovery of the forest floor cover, such as undergrowth and litter layer, the Cs outflow during the monitoring period in the rainy season of Fukushima decreased from 3.24% to 0.61% and 2.79% to 0.03% in the decontaminated and burnt sites, respectively. The forest floor cover ratio of 60% or more is a threshold for an effect on the Cs outflow in the monitoring sites. In the burnt site, a change of dominant outflowed materials from soil particles into litter and its fragments also contributes to the decreasing in the Cs outflow. A protective function of forest floor cover against the soil erosion inherent in the natural forest environment is effective for the migration control of the Cs outflow.
Yonaga, Yusuke; Sano, Naomi*; Amamiya, Hiroki*; Ogita, Yasuhiro; Niwa, Masakazu; Yasue, Kenichi*
Oyo Chishitsu, 62(1), p.2 - 12, 2021/04
Provenance analysis based on quick identification of heavy minerals using an electron probe microanalyzer (EPMA) was applied to samples from Pleistocene sediments in Horonobe region, Hokkaido, where major provenance rocks can be sedimentary and mafic igneous rocks. The concentrations of 16 elements were measured in individual grains to identify the mineral species based on their chemical composition. In addition, microscopic observation of thin sections and gravel composition analysis were conducted to confirm the validity of the quick identification of heavy minerals. These analyses clarify that combinations of several heavy mineral species can be a useful index of provenance rocks from the Soya Hill and Teshio Mountains, and suggest that uplift of the Soya Hill after ca. 1.5 Ma constrained supply of sediments from the Teshio Mountains. On the other hand, minerals uncommon both in the Soya Hill and Teshio Mountains, such as hornblende, are included in the Pleistocene sediments. This suggests that a sediment supply from distant area was also significant, like transportation by the Teshio River. The method for quick identification of heavy minerals using EPMA can provide an information about provenance rocks difficult to identify only by gravel composition analysis.
Niwa, Masakazu; Amamiya, Hiroki*; Yonaga, Yusuke; Ogita, Yasuhiro; Yasue, Kenichi*; Iwano, Hideki*; Danhara, Toru*; Hirata, Takafumi*
Chishitsugaku Zasshi, 126(5), p.267 - 283, 2020/05
U-Pb and fission-track (FT) ages from single zircon grain were measured for three tephra samples (TKB3, TKB6, and TKB7) intercalated in Neogene to Quaternary in Horonobe area, Hokkaido, to understand their depositional ages. In TKB3 and TKB6, weighed average U-Pb and FT ages for zircon grains within the youngest age range are coincident within a range of error 2 
each other, which suggest that their ages correspond to the eruption ages. In TKB7, FT ages for most zircons are reset to their U-Pb ages or younger. The weighed average FT age for all analyzed zircons and weighed average U-Pb age for zircon grains within the youngest age range are coincident within a range of error 2 each other. Thus, their ages could also show the eruption age.
Ishimaru, Tsuneari; Ogata, Nobuhisa; Shimada, Akiomi; Asamori, Koichi; Kokubu, Yoko; Niwa, Masakazu; Watanabe, Takahiro; Saiga, Atsushi; Sueoka, Shigeru; Komatsu, Tetsuya; et al.
JAEA-Research 2018-015, 89 Pages, 2019/03
JAEA-Research-2018-015.pdf:14.43MB
This annual report documents the progress of research and development (R&D) in the 3rd fiscal year during the JAEA 3rd Mid- and Long-term Plan (fiscal years 2015-2021) to provide the scientific base for assessing geosphere stability for long-term isolation of the high-level radioactive waste. The planned framework is structured into the following categories: (1) Development and systematization of investigation techniques, (2) Development of models for long-term estimation and effective assessment, (3) Development of dating techniques. In this report, the current status of R&D activities with previous scientific and technological progress is summarized.
Nomura, Katsuhiro; Tanikawa, Shinichi*; Amamiya, Hiroki; Yasue, Kenichi
JAEA-Data/Code 2016-015, 49 Pages, 2017/03
JAEA-Data-Code-2016-015.pdf:2.88MB
The uplift of the last hundred thousand years in the Japanese Islands has been acquired mainly using marine and river terraces. We arranged information regarding the uplift in a table. This data is one of the useful information for the development of the investigation technology of uplift and for the research of the landform evolution in Japanese islands.
Kirishima, Akira*; Kuno, Atsushi*; Amamiya, Hiroki; Kubota, Takumi*; Kimuro, Shingo*; Amano, Yuki; Miyakawa, Kazuya; Iwatsuki, Teruki; Mizuno, Takashi; Sasaki, Takayuki*; et al.
Chemosphere, 168, p.798 - 806, 2017/02
Times Cited Count：3 Percentile：10.21(Environmental Sciences)For better understanding of the migration behavior of minor actinides (MA) in deep groundwater, the interaction of doped rare earth elements (REEs) and components in Horonobe deep groundwater was studied. Appx. 10 ppb of rare earth elements, i.e., Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Er, Tm and Yb were doped to the sample groundwater collected from a packed sections in borehole drilled from 140 m depth experiment drift of Horonobe underground research laboratory (URL), Hokkaido, Japan. Then, that groundwater was sequentially filtrated by 0.2 micron pore filter, 10 kDa, 3 kDa and 1 kDa of nominal molecular weight limit (NMWL) ultrafilters by keeping inert condition. After that, the filtrate solutions were analyzed by ICP-MS to determine the concentrations of retained REEs at each filtration steps, while the used filters were analyzed by the neutron activation analysis (NAA) and TOF-SIMS element mapping to know the amount and chemical speciation of trapped fraction of the REEs on each filter. A remarkable relation between the retention ratios of REEs in the filtrate solutions and the ionic radius was observed, i.e., smaller rare earth element solves more in liquid phase under the Horonobe groundwater condition. NAA and TOF-SIMS analyses revealed that certain portions of REEs were trapped by 0.2 micron pore filters as rare earth phosphates which corresponded with the predicted predominant species by a chemical equilibrium calculation for the Horonobe groundwater condition, while small portions of colloidal REEs were trapped by 10 kDa and 3 kDa NMWL ultrafilters. The result suggested that phosphate anion plays an important role in the chemical behavior of REEs in saline (seawater based) groundwater, which could be referred for the prediction of migration behavior of trivalent actinide released from the repository of radioactive waste in far future.
Murakami, Hiroaki; Amano, Yuki; Amamiya, Hiroki; Sasaki, Yoshito; Iwatsuki, Teruki; Yoshikawa, Hideki
no journal, ,
no abstracts in English
Sasaki, Yoshito; Asano, Takahiro*; Ise, Kotaro; Sato, Tomofumi; Murakami, Hiroaki; Amamiya, Hiroki; Amano, Yuki; Iwatsuki, Teruki; Yoshikawa, Hideki
no journal, ,
no abstracts in English
Ise, Kotaro; Nanjo, Isao; Amamiya, Hiroki; Amano, Yuki; Iwatsuki, Teruki; Asano, Takahiro*; Kageyama, Koji*; Sasaki, Yoshito; Yoshikawa, Hideki
no journal, ,
no abstracts in English
Kirishima, Akira*; Kuno, Atsushi*; Amamiya, Hiroki; Murakami, Hiroaki; Amano, Yuki; Iwatsuki, Teruki; Mizuno, Takashi; Kubota, Takumi*; Sasaki, Takayuki*; Sato, Nobuaki*
no journal, ,
For understanding of the migration behavior of minor actinides (MA) in groundwater, the interaction of rare earth elements and suspended matters contained in Horonobe deep groundwater was studied. From this chemical analog study, it is suggested that the migration behavior of MA in the Horonobe groundwater system seems to be regulated by the formation of phosphate precipitation and small percentage of MA would be carried in the groundwater as pseudo colloids like MA-humic substance complex.
Amano, Yuki; Amamiya, Hiroki; Murakami, Hiroaki; Iwatsuki, Teruki; Terashima, Motoki; Mizuno, Takashi; Kirishima, Akira*; Kuno, Atsushi*; Sasaki, Takayuki*; Kubota, Takumi*; et al.
no journal, ,
no abstracts in English
Kirishima, Akira*; Kuno, Atsushi*; Amamiya, Hiroki; Murakami, Hiroaki; Amano, Yuki; Iwatsuki, Teruki; Mizuno, Takashi; Kubota, Takumi*; Sasaki, Takayuki*; Sato, Nobuaki*
no journal, ,
no abstracts in English
Kokami, Takayuki*; Sasaki, Takayuki*; Amamiya, Hiroki; Murakami, Hiroaki; Amano, Yuki; Iwatsuki, Teruki; Mizuno, Takashi; Kubota, Takumi*; Kirishima, Akira*
no journal, ,
no abstracts in English
Amano, Yuki; Sasaki, Yoshito; Nanjo, Isao*; Amamiya, Hiroki; Mizuno, Takashi; Ise, Kotaro; Yoshikawa, Hideki
no journal, ,
Continuous monitoring of groundwater chemistry of the boreholes during the facility construction indicated that the salinity around 140 m have not changed from the beggining to date. Water pressures within the area several tens to hundreds meter from the shafts also went down in process of time. Regarding the chemical disturbance in the area, the redox potencial of the groundwaters in the monitoring boreholes showed reducing condition nevertheless the gallery is in oxidized condition. However, microbial community structure changed considerably from the beggining to date. These results indicate that microbial redox reaction could contribute to maintain of reducing conditions in the groundwater system, despite of hydrochemical disturbance caused by facility construction.
Amano, Yuki; Ise, Kotaro; Terashima, Motoki; Sasaki, Yoshito; Amamiya, Hiroki; Yoshikawa, Hideki
no journal, ,
Microorganisms are widely distributed in the subsurface environments. However, the distribution, role and rate of metabolisms, and the origin of the activity are not well known. In this study, we investigated deep groundwater samples of sedimentary rocks, which is contained supersuturated methane and carbon dioxide, using boreholes in the Horonobe Underground Research Laboratory (URL), in the northern part of Hokkaido, Japan. Abundant methanogens were detected in the groundwater, and 80% of them were related to Methanoregula boonei and Methanobacterium flexile that can utilize hydrogen and carbon dioxide as methanogenesis. Phylotypes clustered within the phylum Firmicutes, beta-Proteobacteria, delta-Proteobacteria and Candidatte division TM7 were dominant in the groundwater samples. Laboratory experiment using culture a technique showed that humic substances purified from Horonobe area could be degraded by microorganisms. Our results suggest that microbial spatial distribution in the subsurface environment was correlate closely with geochemical conditions, such as redox condition and carbon sources.
Amamiya, Hiroki; Mizuno, Takashi; Iwatsuki, Teruki; Yuguchi, Takashi; Murakami, Hiroaki; Kokubu, Yoko
no journal, ,
The long-term evolution of geochemical environment in deep underground is indispensable research subject for geological disposal of high-level radioactive waste. Many researchers have made efforts previously to elucidate the geochemical environment within the groundwater residence time based on the analysis of the actual groundwater. However, it is impossible to estimate the geochemical environment for the longer time scale than the groundwater residence time in this method. In this case, analysis of the chemical properties of secondary minerals are one of useful method to estimate the past hydrochemical characteristics (temperature, salinity, pH and redox potential). We reviewed the previous studies on carbonate minerals and geochemical conditions in deep underground and estimated the hydrochemical characteristics of past groundwater by using carbonate minerals in crystalline rock at Tono area, Japan. As a result, it is found that temperature and salinity of the groundwater during crystallization of carbonate minerals were evaluated quantitatively. On the other hand, pH and redox potential can only be understood qualitatively. However, it is suggested that the content of heavy metal elements such as manganese, iron and uranium, and rare earth elements in the carbonate minerals are useful indicators for estimating redox potential.
Sasaki, Takayuki*; Kokami, Takayuki*; Amamiya, Hiroki; Murakami, Hiroaki; Amano, Yuki; Iwatsuki, Teruki; Mizuno, Takashi; Kobayashi, Taishi*; Kirishima, Akira*
no journal, ,
For thermodynamic analysis of the trace metals in groundwater, concentrations of Th, U, and rare earth elements (REEs) were investigated at Horonobe Underground Research Laboratory. Groundwater was sampled in anaerobic condition directly from a packed section in the boreholes drilled to 140 m and 250 m depth in drift. The colloidal distribution was checked by an on-site batch ultrafiltration unit using 0.2 
m or 10 kDa membranes. As the result, both Th and U concentrations could be estimated by thermodynamic calculations, assuming that the soluble solid phases are restricted to ThO
(cr) and UO(cr), respectively. Meanwhile, the concentrations of REEs were also very low, and significant colloidal distribution for lighter REEs was observed. In the thermodynamic analysis where the lanthanide phosphate was assumed to be a solid phase, the experimental plots matched better with the calculated one, even though the changing trend differs from each other.
Watanabe, Takahiro; Kokubu, Yoko; Murakami, Hiroaki; Yokoyama, Tatsunori; Amamiya, Hiroki; Mizuno, Takashi; Kubota, Mitsuru; Iwatsuki, Teruki
no journal, ,
Chronological and geochemical studies of fracture filling calcite in rocks provide the information for changes in geochemical condition, such as redox potential and pH in geological environments. Because the calcite can be found as common filling minerals in the natural samples, age zoning and spatial distribution of chemical composition in the calcite could be a wide-use indicator to reconstruct the past environmental changes. Radiometric (U-Pb) dating in a micro scale area (less than 10 micrometer) on the filling mineral surface by laser ablation-inductively coupled plasm mass spectrometry system (LA-ICPMS) has been applied to geological samples. Additionally, past redox potential has been estimated by Fe contents in the carbonates, which is based on the distribution coefficient of Fe between calcite deposit and groundwater. In this study, we evaluated the possibility of in-situ radiometric dating for the filling minerals by LA-ICPMS and redox potential reconstruction by the theoretical calculation using the distribution coefficient.
Watanabe, Tsuyoshi; Asamori, Koichi; Umeda, Koji*; Amamiya, Hiroki; Nomura, Katsuhiro; Nakatsuka, Noboru
no journal, ,
no abstracts in English
Niwa, Masakazu; Shimizu, Mayuko; Yasue, Kenichi; Nishimura, Shusaku; Amamiya, Hiroki; Ueki, Tadamasa; Horiuchi, Yasuharu
no journal, ,
Uplift and associated denudation of mountains affect hydraulic gradient and groundwater flow path. In the case of a safety assessment for geological disposal of radioactive wastes, uplift and denudation will be examined in terms of nuclide migration driven by deep groundwater as well as potential exposure of repositories. Provenance analysis based on sedimentological, petrological, mineralogical and geochemical approaches in downstream area is often helpful for understanding onset times and processes of uplift and associated denudation of mountains in upstream area. In this study, quick quantification analysis for heavy minerals and measurement of electron spin resonance signal for quartz to estimate provenance rocks, and paleo-current analysis using magnetic anisotropy of susceptibility for fine sand were developed.
