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Itoi, Hiroyuki*; Ninomiya, Takeru*; Hasegawa, Hideyuki*; Maki, Shintaro*; Sakakibara, Akihiro*; Suzuki, Ryutaro*; Kasai, Yuto*; Iwata, Hiroyuki*; Matsumura, Daiju; Owada, Mao*; et al.
Journal of Physical Chemistry C, 124(28), p.15205 - 15215, 2020/07
Times Cited Count:8 Percentile:39.3(Chemistry, Physical)Suzuki, 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.
Suzuki, Takashi; Otosaka, Shigeyoshi; Kuwabara, Jun; Kawamura, Hideyuki; Kobayashi, Takuya
Marine Chemistry, 204, p.163 - 171, 2018/08
Times Cited Count:2 Percentile:10.67(Chemistry, Multidisciplinary)To investigate the penetration of radionuclides released from Fukushima Daiichi Nuclear Power Plant (FDNPP), depth profiles were revealed at Kuroshio current, transition, and Oyashio current areas. The FDNPP-derived I was found in surface layer at Oyashio current and transition areas and in sub-surface layer at Kuroshio current area. Moreover, it was found that the FDNPP-derived I/Cs ratios in the Oyashio current and transition areas were higher than that in the FDNPP reactor. The higher FDNPP-derived I/Cs ratios suggest three potential mechanisms for the migration of radionuclides in the environment: (1) radioiodine was released more easily than radiocesium by the FDNPP accident, (2) I was supplied from the atmosphere by re-emitted I from contaminated areas around Fukushima, (3) leaked water that removed radiocesium reached the sampling stations. The FDNPP-derived I in sub-surface layer would be transported by the meander of the Kuroshio Extension current.
Suzuki, Shigemasa*; Kaira, Kyoichi*; Ohshima, Yasuhiro; Ishioka, Noriko; Soda, Makoto*; Yokobori, Takehiko*; Miyazaki, Tatsuya*; Oriuchi, Noboru*; Tominaga, Hideyuki*; Kanai, Yoshikatsu*; et al.
British Journal of Cancer, 110(8), p.1985 - 1991, 2014/04
Times Cited Count:24 Percentile:60.2(Oncology)Suzuki, Takashi; Otosaka, Shigeyoshi; Kuwabara, Jun; Kawamura, Hideyuki; Kobayashi, Takuya
Biogeosciences, 10(6), p.3839 - 3847, 2013/06
Times Cited Count:24 Percentile:57.49(Ecology)no abstracts in English
Otosaka, Shigeyoshi; Suzuki, Takashi; Tanaka, Takayuki; Ito, Toshimichi; Kobayashi, Takuya; Kawamura, Hideyuki; Minakawa, Masayuki*; Aramaki, Takafumi*; Senju, Tomoharu*; Togawa, Orihiko
JAEA-Data/Code 2009-020, 27 Pages, 2010/02
The database for the Japan Sea parameters on marine environment and radionuclides (JASPER) has been established by the Japan Atomic Energy Agency as a product of the Japan Sea Expeditions. By the previous version of the database, data for representative anthropogenic radionuclides were opened to public. And now, data for radiocarbon and fundamental oceanographic properties (salinity, temperature, dissolved oxygen) including nutrients (silicate, phosphate, nitrate and nitrite) are released as the second volume of the database. In the second volume, 20,398 data records are stored including 2,695 data for temperature, 2,883 data for salinity, 2,109 data for dissolved oxygen, 11,051 data for the nutrients, and 1,660 data for radiocarbon. The database will be a strong tool for the continuous monitoring for contamination by anthropogenic radionuclides, studies on biogeochemical cycle, and development and validation of models for numerical simulations in the sea.
Sumiyoshi, Kosuke*; Yamada, Shoichi*; Suzuki, Hideyuki*; Chiba, Satoshi
Physical Review Letters, 97(9), p.091101_1 - 091101_4, 2006/09
Times Cited Count:102 Percentile:93.1(Physics, Multidisciplinary)no abstracts in English
Otosaka, Shigeyoshi; Amano, Hikaru; Ito, Toshimichi; Kawamura, Hideyuki; Kobayashi, Takuya; Suzuki, Takashi; Togawa, Orihiko; Chaykovskaya, E. L.*; Lishavskaya, T. S.*; Novichkov, V. P.*; et al.
Journal of Environmental Radioactivity, 91(3), p.128 - 145, 2006/00
Times Cited Count:20 Percentile:42.09(Environmental Sciences)Distributions of radionuclides (Sr, Cs and Pu) in seabed sediment in the Japan Sea were observed during 1998-2002. Observed inventories of anthropogenic radionuclides in sediment ranged 0.1-86 Bq m for Sr, 23-379 Bq m for Cs and 0.1-86 Bq m for Pu. In the deep part ( 2 km depth) of the western Japan Basin, Pu/Cs inventory ratios were larger than those in the central Yamato Basin although inventories of radionuclides were not different between basins. The higher Pu/Cs ratios in the western Japan Basin were derived by the production of Pu-enriched particle in the surface layer and effective sinking of particulate materials in this region. In the marginal Yamato Basin and the Ulleung Basin, both inventories and Pu/Cs ratios in sediment were larger than those in the central Yamato Basin. In the eastern/southern Japan Sea, it was suggested that the supply of particulate radionuclides by the TWC enhanced accumulation of radionuclides in this region.
Sumiyoshi, Kosuke*; Yamada, Shoichi*; Suzuki, Hideyuki*; Shen, H.*; Chiba, Satoshi; Toki, Hiroshi*
Astrophysical Journal, 629(2, Part1), p.922 - 932, 2005/08
Times Cited Count:230 Percentile:97.4(Astronomy & Astrophysics)no abstracts in English
Ito, Toshimichi; Aramaki, Takafumi*; Otosaka, Shigeyoshi; Suzuki, Takashi; Togawa, Orihiko; Kobayashi, Takuya; Kawamura, Hideyuki; Amano, Hikaru; Senju, Tomoharu*; Chaykovskaya, E. L.*; et al.
Journal of Nuclear Science and Technology, 42(1), p.90 - 100, 2005/01
Times Cited Count:14 Percentile:67.75(Nuclear Science & Technology)During 1996-2002, a wide-area research project on anthropogenic radionuclides was done in the Japanese and Russian EEZ of the Japan Sea to investigate their migration. As the results of expeditions in 2001 and 2002, (1) the concentrations and distributions of radionuclides are similar to the results of previous, (2) inventories of these radionuclides indicate accumulation in the Japan Sea seawater compared to the amounts supplied by global fallout, (3) Sr and Cs concentrations in intermediate layer show temporal variations, and 4) the variations may reflect the water mass movement in upper part of the Japan Sea.
Otosaka, Shigeyoshi; Ito, Toshimichi; Kawamura, Hideyuki; Kobayashi, Takuya; Suzuki, Takashi; Togawa, Orihiko
Dai-45-Kai Kankyo Hoshano Chosa Kenkyu Seika Rombun Shorokushu (Heisei-14-Nendo), p.77 - 78, 2003/12
no abstracts in English
Wada, Yukio; Funasaka, Hideyuki; Myochin, Munetaka; Yamamoto, Kazunori; Harada, Hideo; ;
PNC TN8100 96-005, 16 Pages, 1996/01
no abstracts in English
Otosaka, Shigeyoshi; Kobayashi, Takuya; Kawamura, Hideyuki; Suzuki, Takashi
no journal, ,
Based on oceanographic observations and numerical simulations, dispersion and sedimentation processes of radionuclides released from the Fukushima Dai-ichi NPP were summarized. An oceanic dispersion simulation indicated that, (1) in the middle of March, 2011, radionuclides released to the atmosphere mainly deposited on the surface of the northeastern regions of Fukushima Prefecture, and (2) radionuclides released directly to the ocean were transported southward along the coast of Fukushima and Ibaraki Prefectures. Observational results indicated that (3) most radiocesium in seabed sediment was transported by the above-mentioned process (2), and adsorbed on sediments in the coastal regions within 6 months after the accident.
Sato, Junya; Suzuki, Shinji*; Kato, Jun; Sakakibara, Tetsuro; Nakazawa, Osamu; Meguro, Yoshihiro; Ueda, Hiroshi*; Kurosaki, Fumio*; Yoneyama, Takashi*; Matsukura, Minoru*; et al.
no journal, ,
no abstracts in English
Suzuki, Takashi; Otosaka, Shigeyoshi; Kuwabara, Jun; Kawamura, Hideyuki; Kobayashi, Takuya
no journal, ,
no abstracts in English