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Watanabe, Tsuyoshi; Saiga, Atsushi; Asamori, Koichi; Ogawa, Hiroki; Shimada, Akiomi; Umeda, Koji*
no journal, ,
no abstracts in English
Sueoka, Shigeru; Komatsu, Tetsuya; Matsushi, Yuki*; Yonaga, Yusuke; Sano, Naomi; Hirao, Noriaki*; Ueki, Tadamasa; Fujita, Natsuko; Kokubu, Yoko; Niwa, Masakazu
no journal, ,
no abstracts in English
Fukuda, Shoma*; Sueoka, Shigeru; Kohn, B. P.*; Hasebe, Noriko*; Tamura, Akihiro*; Morishita, Tomoaki*; Tagami, Takahiro*
no journal, ,
no abstracts in English
Yokoyama, Tatsunori; Mitsuguchi, Takehiro; Sueoka, Shigeru
no journal, ,
In recent years, it has become possible to carry out high-precision microscale age dating of geological samples using developed micro-analytical techniques such as SIMS, LA-ICP-MS, etc. Application of LA-ICP-MS-based microscale U-Pb dating is extending from U-rich heavy minerals such as zircon, apatite and monazite to U-depleted minerals such as calcite. This kind of method enables age determination of several types of mineral grains occurring within rock bodies, and thereby reveals chronological changes in chemical composition of source materials from which the minerals were crystallized, with some cases in which thermal history of the crystal formation system can be reconstructed. For research and development of geological disposal techniques for high-level radioactive wastes, we develop and facilitate geochronological dating techniques for evaluation of long-term stability in geological environments, at Tono Geoscience Center, Japan Atomic Energy Agency. In our presentation, we introduce the current status of our development for research on long-term stability of geological environments, U-Pb dating of calcite, U-Pb dating of young zircon and trace element analysis by using LA-ICP-MS.
Murakami, Hiroaki; Watanabe, Yusuke; Fukuda, Kenji; Iwatsuki, Teruki
no journal, ,
To understand geological-environment stability at the deep underground, it is important to monitor changes in EdZ. Monitoring after closure of underground facilities is particularly important, however few studies have been reported on post-closure monitoring. We considered about focus points of post-closure monitoring by using hydrochemical data of groundwater in/around Mizunami Underground Research Laboratory. In highly permeable strata such as conglomerate formation, the source of groundwater changes due to URL construction and operation. In this section after URL closure, the water pressure will recover and the source of the groundwater will change again. Therefore, the section greatly influenced by the facility construction and operation should be chosen for post-closure monitoring.
Hiura, Yuki; Komatsu, Tetsuya; Sugai, Toshihiko*
no journal, ,
no abstracts in English
Ogata, Manabu; King, G.*; Herman, F.*; Sueoka, Shigeru
no journal, ,
no abstracts in English
Niwa, Masakazu; Shimada, Koji
no journal, ,
In the field of archaeology, the diffusion of water into quartz exposed to the natural environment has been proposed as a dating method (quartz hydration dating: QHD) applicable to archaeological artifacts. We examined application of QHD to geologic materials to understand geological phenomena such as uplift and erosion, faulting, and hydrothermal activity. According to hydrothermal experiments and SIMS analyses for natural granite samples, the QHD can be promising as a new tool to understand geological phenomena.
Nakanishi, Toshimichi; Komatsu, Tetsuya; Ogata, Manabu; Hosoya, Takashi*; Kaga, Takumi*
no journal, ,
no abstracts in English
Tateishi, Ryo*; Shimada, Koji; Ueki, Tadamasa; Shimizu, Mayuko; Komatsu, Tetsuya; Sueoka, Shigeru; Niwa, Masakazu; Yasue, Kenichi*; Ishimaru, Tsuneari
no journal, ,
no abstracts in English
Sato, Tatsuhiko; Kataoka, Ryuho*; Shiota, Daiko*; Kubo, Yuki*; Ishii, Mamoru*; Yasuda, Hiroshi*; Miyake, Shoko*; Park, I.*; Miyoshi, Yoshizumi*
no journal, ,
We are developing a physics-based warning system for aviation exposure to solar energetic particles, WASAVIES, under the framework of the PSTEP project in Japan. It can nowcast and forecast the radiation dose rates all over the world up to 24 h after the large solar flare onset. The performance of WASAVIES is examined by analyzing the three major GLE events of the 21st century. The accuracy of the calculated dose rates is well validated by the reproducibility of the count rates of several neutron monitors and GOES proton fluxes. A web-interface of WASAVIES is also developed and will be released from March 2019 through the public server of NICT.
Niizato, Tadafumi; Watanabe, Takayoshi; Mitachi, Katsuaki*; Sasaki, Yoshito; Ito, Satomi; Abe, Hironobu
no journal, ,
An understanding of long-term environmental dynamics of radiocesium, which is released by the TEPCO's Fukushima Dai-ichi Nuclear Power Plant accident, is a key issue for predicting the future radiocesium distribution and forest products radioactivity in a forested environment, especially 
Cs with half-life of 30 years. We compiled the five-years monitoring results of radiocesium input-output budgets in broad-leaved deciduous forests and Japanese cedar evergreen forests of the Abukuma Mountains, Fukushima, Japan. The input-output rates were a few percent of the radiocesium inventory of the monitoring site. In addition, both rates have been decreasing with time. Belowground radiocesium occupied 90% of the total inventory in the Japanese cedar forest on October 2015. The belowground radiocesium was distributed mainly in the topsoil of 0-6 cm depth, approximately 70-80% of the underground inventory on August 2016. These results indicate that the distribution of radiocesium in the forest is similar to the distribution of tree rootlet responsible for absorption of inorganic elements, nutrients, and water. This means long residence time of radiocesium in rooting zone. In the condition of the limited amount of radiocesium input-output rates in the forest, estimation of the migration flux of radiocesium from forest floor to the forest products are considered to be most important issues in the present.
Osawa, Kota*; Niizato, Tadafumi; Mitachi, Katsuaki*; Kawamura, Makoto*; Okawa, Masahiro*
no journal, ,
Primary outflow process of radiocesium, which is released by the TEPCO's Fukushima Dai-ichi Nuclear Power Plant accident, from a forest slope to a mountain stream is a particulate-bond state transport. A detailed estimation of riverbed form and sediment volume changing with time is a key issue to assess the radiocesium distribution in the forested environment. We attempt to restore the three-dimensional structure of underwater riverbed form in the mountain stream from the captured digital images by applying the SfM (Structure from Motion) and MVS (Multi View Stereo) technologies. Discrepancy between measured and analytical results increase with depth, the estimation errors are 73% and 93% in the depth of 20-25 cm and 10-15 cm, respectively. Next step is an improvement of the correction and image-capturing methods to reduce the estimation errors by elimination of the light refraction on the stream water surface.
Fukuda, Kenji; Murakami, Hiroaki; Itai, Kaori*; Ishibashi, Masayuki; Sasao, Eiji
no journal, ,
Matrix diffusion is one of the important for evaluating solute transport in granite. Diffusion of ions in granite pore water was studied in order to evaluate diffusivity in rock. Effective diffusion coefficient of uranine was measured using a diffusion cell. The effective diffusion coefficient of uranine in granite without fissure and alteration was found to be in the range 10
to 10
m
s
. The porosities of the granite samples were determined by observation of petrographic thin sections using entity fluorescence microscope. There was a positive correlation between the porosity larger than 1% and the effective diffusion coefficient.
Komatsu, Tetsuya; Hiura, Yuki; Takahashi, Takayuki*; Funatsu, Taro*; Muraki, Masahiro*; Kimori, Taiga*; Sugai, Toshihiko*
no journal, ,
no abstracts in English
Sasaki, Yoshito; Niizato, Tadafumi; Mitachi, Katsuaki*; Ito, Satomi; Watanabe, Takayoshi
no journal, ,
no abstracts in English
Kobayashi, Yumi*; Sueoka, Shigeru; Fukuda, Shoma*; Kohn, B. P.*; Yokoyama, Tatsunori; Hasebe, Noriko*; Tamura, Akihiro*; Morishita, Tomoaki*; Tagami, Takahiro*
no journal, ,
no abstracts in English
Kajita, Yuya*; Sueoka, Shigeru; Fukuda, Shoma*; Hasebe, Noriko*; Tamura, Akihiro*; Morishita, Tomoaki*; Kohn, B. P.*; Yokoyama, Tatsunori; Tagami, Takahiro*
no journal, ,
no abstracts in English
Sasao, Eiji; Yuguchi, Takashi*; Ishibashi, Masayuki
no journal, ,
The authors studied cooling process of granitic magma in the Toki granite, distributed in the southwestern part of Gifu Prefecture, central Japan, based on petrological, mineralogical and themochronological methodologies. We also compare the relationship between magma cooling process, and fracture distribution and micropore in plagioclase. As a result, we estimated that the imhomogeneous distribution of fracture and micropore in plagioclase were formed by cooling process of granitic magma. We present the relationship between formation of the pathway of groundwater and mass transport, and cooling process of granitic rock.
release from volcanic ash soilsNagano, Hirohiko; Atarashi-Andoh, Mariko; Koarashi, Jun
no journal, ,
Global warming may increase seasonal fluctuation of soil water conditions. Soil temperature and water fundamentally affect soil CO release, a major carbon flux in terrestrial ecosystems. However, our understandings of soil CO release under the increased temperature and fluctuated water conditions are still insufficient to infer the feedback of terrestrial carbon cycling in future worlds. In the present study, we are conducting laboratory incubation experiments for examining the combined effects of temperature rising and soil water fluctuation on CO release from volcanic ash soils. We incubated volcanic ash soils under four combinatorial conditions of two temperatures (20 and 30
C) and two water conditions (a continuously constant water and a fluctuated water conditions). The rate of CO release was periodically measured during the incubation. Then, the ratio of CO release at 20C to that at 30 C, namely Q10, was expressed as the temperature sensitivity of soil CO release. For the incubation at 20 C, soil CO release under the fluctuated water condition was up to 50% greater than that under the constant water condition. The excess of soil CO release under the fluctuated water condition was, however, reduced to less than 10% for the incubation at 30C. Thus, Q10 under the fluctuated water condition (1.3 to 1.5) was equivalent to or lower than that under the continuously constant water condition (around 1.5). These preliminary results offer the needs of modifying basal CO release extent and Q10 value for inferring the soil CO release under increased temperature and fluctuated water conditions. The experiments are still ongoing and results and further insights will be presented at the meeting.