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Niizato, Tadafumi; Sasaki, Yoshito; Amamiya, Hiroki*
Dai-32-Kai Shakai Chishitsugaku Shimpojiumu Rombunshu, p.13 - 16, 2022/11
Cs outflow associated with hillslope process on the mountain slope and riverbed sedimentation process in the mountain stream was estimated by using of the one-year monitoring result in a mountainous forest of Fukushima, Japan. The Cs outflow rate per monitoring period was 0.23% for the mountain slope (27 April - 14 Dec. 2017) and 0.02% for the mountain stream (27 June 2017 - 17 April 2018). Comparing with the daily flux, Cs outflow in the mountain slope was 18 times higher than that in the mountain stream. In terms of riverbed sediment load and Cs activity, we point out the possibility of a relatively low contribution of Cs-137 in the forested area to the watershed Cs discharge.
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：8.89(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.
Kirishima, Akira*; Kuno, Atsushi*; Amamiya, Hiroki; Murakami, Hiroaki; Amano, Yuki; Iwatsuki, Teruki; Mizuno, Takashi; Kubota, Takumi*; Sasaki, Takayuki*; Sato, Nobuaki*
no journal, ,
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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.
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.
Amamiya, Hiroki; Niwa, Masakazu
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Yonaga, Yusuke; Sano, Naomi*; Amamiya, Hiroki*; Niwa, Masakazu; Yasue, Kenichi*
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Niizato, Tadafumi; Sasaki, Yoshito; Watanabe, Takayoshi; Ito, Satomi; Amamiya, Hiroki*
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Niizato, Tadafumi; Sasaki, Yoshito; Ito, Satomi; Watanabe, Takayoshi; Amamiya, Hiroki*
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An understanding of long-term environmental dynamics of radiocesium in forested area, which is released by the TEPCO's Fukushima Daiichi Nuclear Power Plant accident, is a key issue for predicting the future forest products radioactivity. In this paper we present the radiocesium uptake from forest floor in an evergreen Japanese cedar and a deciduous Japanese konara oak forests of the Abukuma Mountains, Fukushima. An investigation was conducted from 2015 to 2019. According to the International Biological Programme, IBP, annual radiocesium uptake from forest floor to the stand is estimated as follows; annual radiocesium increment associated with tree growth plus annual loss through litterfall, stemflow, and throughfall. The rate of annual radiocesium uptake to the total inventory of the stands associated with tree growth were estimated to be 0.1 and 0.06% in Japanese konara oak and Japanese cedar stands, respectively. The sum of radiocesium uptake including the loss of radiocesium amount by litterfall, stemflow, and throughfall were 1.37 and 3.13% in the konara oak and the cedar stands, respectively. The rate of radiocesium uptake estimated are lower than the elemental uptake in deciduous tree stands near Kyoto by IBP. This indicate that the radiocesium uptake by the konara oak and the cedar stands is limited and no significant increase in radiocesium concentration of tree tissues is expected in the study stands.
Niizato, Tadafumi; Sasaki, Yoshito; Amamiya, Hiroki*; Yoshida, Kaori
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Ito, Eimi*; Takeuchi, Shinji*; Niizato, Tadafumi; Sasaki, Yoshito; Amamiya, Hiroki*
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Murakami, Hiroaki; Amano, Yuki; Amamiya, Hiroki; Sasaki, Yoshito; Iwatsuki, Teruki; Yoshikawa, Hideki
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Atsumi, Reika*; Niizato, Tadafumi; Takeuchi, Shinji*; Amamiya, Hiroki*
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Sasaki, Yoshito; Asano, Takahiro*; Ise, Kotaro; Sato, Tomofumi; Murakami, Hiroaki; Amamiya, Hiroki; Amano, Yuki; Iwatsuki, Teruki; Yoshikawa, Hideki
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Ise, Kotaro; Nanjo, Isao; Amamiya, Hiroki; Amano, Yuki; Iwatsuki, Teruki; Asano, Takahiro*; Kageyama, Koji*; Sasaki, Yoshito; Yoshikawa, Hideki
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no abstracts in English
