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Watanabe, Takahiro; Kokubu, Yoko; Fujita, Natsuko; Ishizaka, Chika*; Nishio, Tomohiro; Matsubara, Akihiro*; Miyake, Masayasu; Kato, Motohisa*; Isozaki, Nobuhiro*; Torazawa, Hitoshi*; et al.
JAEA-Conf 2018-002, p.116 - 119, 2019/02
AMS is widely used for radiocarbon dating of geological samples. However, improvement in efficiency of sample preparation techniques are needed for high-time resolution dataset. In 2016, automated graphitization equipment (AGE3, IonPlus AG) has been installed in Toki Research Institute of Isotope Geology and Geochronology, Tono Geoscience Center, JAEA. Background values and carbon recovery rates during preparation process of AGE3 should be estimated before application in radiocarbon dating. In this study, the AGE3 system was evaluated using the international standard materials (IAEA-C1, C4, C5, C6, C7, C9 and NIST-SRM4990C) at JAEA-AMS-TONO. Graphite samples was prepared by the AGE3 system and radiocarbon concentration of these standards was measured by AMS. The results were agreement with the consensus values. Background values were 0.15
0.01 pMC (IAEA-C1) using the AGE3 system. Therefore, we concluded that the system can be adapted for radiocarbon dating of geological samples.
I released from Fukushima Daiichi Nuclear Power Plant accident in the western North Pacific OceanSuzuki, Takashi; Otosaka, Shigeyoshi; Kuwabara, Jun; Kawamura, Hideyuki; Kobayashi, Takuya
JAEA-Conf 2018-002, p.103 - 106, 2019/02
To investigate the dynamics of radionuclides in the ocean released by the accident at Fukushima Daiichi Nuclear Power Plant (1F), vertical distributions of I at three stations in the western North Pacific was revealed. The 1F accident-derived I existed within the mixed layer at 3 stations. The maximum layer of the 1F accident-derived I existed at the depth of 370 m - 470 m at the most southern station. Considering the dissolved oxygen concentration and the current velocity arround the station, the maximum layer of the 1F accident-derived I would be fromed that I which existed in the surface seawater at other area of observation point was carried to the depth of 370 m - 470 m by the fast downward flow.
I/
I ratio at JAEA-AMS-TONOOkabe, Nobuaki; Fujita, Natsuko; Matsubara, Akihiro*; Miyake, Masayasu; Nishio, Tomohiro*; Nishizawa, Akimitsu*; Isozaki, Nobuhiro*; Watanabe, Takahiro; Kokubu, Yoko
JAEA-Conf 2018-002, p.51 - 54, 2019/02
no abstracts in English
Matsubara, Akihiro*; Fujita, Natsuko; Miyake, Masayasu; Isozaki, Nobuhiro*
JAEA-Conf 2018-002, p.68 - 71, 2019/02
no abstracts in English
Kokubu, Yoko; Fujita, Natsuko; Matsubara, Akihiro*; Nishizawa, Akimitsu*; Nishio, Tomohiro; Miyake, Masayasu; Ishimaru, Tsuneari; Watanabe, Takahiro; Ogata, Nobuhisa; Shimada, Akiomi; et al.
JAEA-Conf 2018-002, p.5 - 8, 2019/02
no abstracts in English
Be of the rock samples from the lake terrace of the Lake Pumayum Co in Tibetan PlateauNara, Fumiko*; Watanabe, Takahiro; Kokubu, Yoko; Horiuchi, Kazuho*
JAEA-Conf 2018-002, p.124 - 127, 2019/02
In-situ cosmogenic radionuclides have been used to understand earth surface processes, such as the erosion rate and exposure age dating of rocks. This is a preliminary report on in-situ Be values measurements by Accelerator Mass Spectrometry (AMS) for rock samples from the shore of the Lake Pumoyum Co in Tibetan plateau. The Be concentrations ranged from 5.5-7.5
10
atom/g similar to those of the surface sediments of Lake Pumoyum Co. The calculated erosion rates were 5.2-7.6 mm/kyr, values close to those previously reported by Lal et al. (2003).
Be concentrations in bed-sediments of Ado and Yasu rivers flowing into Lake BiwaFujisawa, Jumpei*; Minami, Masayo*; Kokubu, Yoko; Matsuzaki, Hiroyuki*
JAEA-Conf 2018-002, p.91 - 94, 2019/02
Beryllium-10 (Be) of a cosmogenic nuclide precipitates in forms of BeO and Be(OH)
attaching with aerosol on the Earth surface. It is accumulated on the sea- and lake-bottoms. Recently, the meteoric Be is attracting attention as a powerful tool for investigating the past climate change, because it is affected by the earth- and lorcal- cyclical changes of materials such as atmosphere and water circulation. The Be exists mostly as hydroxide at pH 
5, and is easy to adhere to soil and mineral surface. Therefore, Be concentration in sediment could be influenced by its grain size composition because fine-grained sediment has a big surface area per unit mass. The purpose of this study is to reveal the relationship between Be concentrations and the grain-size of river sediments. The samples used were bottom-sediments of 18 rivers flowing into Lake Biwa, Japan. The sediments were sieved to 5 fractions and analyzed each for Be concentration by JAEA-AMS-TONO.
Cl in soil near the Fukushima Dai-ichi Nuclear Power PlantOta, Yuki*; Sueki, Keisuke*; Sasa, Kimikazu*; Takahashi, Tsutomu*; Matsunaka, Tetsuya*; Matsumura, Masumi*; Tosaki, Yuki*; Honda, Maki*; Hosoya, Seiji*; Takano, Kenta*; et al.
JAEA-Conf 2018-002, p.99 - 102, 2019/02
no abstracts in English
Jeon, H.; Otosaka, Shigeyoshi; Watanabe, Takahiro; Aze, Takahiro*; Miyairi, Yosuke*; Yokoyama, Yusuke*; Ogawa, Hiroshi*
no journal, ,
Measurements of the dissolved organic radio carbon (DOC-14) are expected to broaden our perspective on the role of DOC in the marine carbon cycle. Although the authors had succeeded in the DOC-14 analysis in seawater, it was necessary to use a large preprocessing apparatus, and the analysis has not been applied widely. We here report on the improvements to make this system safer and easier to handle. Following the previous method, DOC-14 in seawater was extracted as carbon dioxide by irradiating ultraviolet (UV), purified in a vacuum line, and the C-14 isotopic ratio was analysed with an accelerator mass spectrometer. As a major improvement, low-pressure mercury lamp which can irradiate UV of short wavelength (172 nm and 185 nm) suitable for decomposition of organic matter was used as UV source. By this improvement, the temperature increase in sample during processing was greatly reduced, and the size of the irradiation reactor was reduced to about half.
Watanabe, Takahiro; Nara, Fumiko*
no journal, ,
Geochronological study of lacustrine and land sediments has been reported based on radiocarbon measurements by accelerator mass spectrometry. In particular, the studies on past climate changes and tsunami geology using the sediments have been proceeded (Watanabe et al., 2009; 2010; 2012; Nara et al., 2014). In this presentation, standard methods for radiocarbon dating of the lacustrine and land sediments are shown. These methods are applied to dating of tsunami deposits for disaster science in this study. We tried to make an age model of tsunami deposits using these methods.
Sr-AMS with the 6 MV tandem acceleratorHosoya, Seiji*; Sasa, Kimikazu*; Takahashi, Tsutomu*; Honda, Maki*; Satou, Yukihiko; Takano, Kenta*; Ochiai, Yuta*; Sueki, Keisuke*
no journal, ,
no abstracts in English
