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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：42.21(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.
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：67.84(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.
Ito, Toshimichi; Aramaki, Takafumi*; Otosaka, Shigeyoshi; Suzuki, Takashi; Togawa, Orihiko; Kobayashi, Takuya; Senju, Tomoharu*; Chaykovskaya, E. L.*; Lishavskaya, T. S.*; Karasev, E. V.*; et al.
Proceedings of International Symposium on Radioecology and Environmental Dosimetry, p.396 - 401, 2003/10
no abstracts in English
Tkalin, A. V.*; Lishavskaya, T. S.*; Belan, T. A.*; Karasev, E. V.*; Togawa, Orihiko
Pacific Oceanography, 1(1), p.42 - 52, 2003/08
no abstracts in English
Ito, Toshimichi; Aramaki, Takafumi; Kitamura, Toshikatsu; Otosaka, Shigeyoshi; Suzuki, Takashi; Togawa, Orihiko; Kobayashi, Takuya; Senju, Tomoharu*; Chaykovskaya, E. L.*; Karasev, E. V.*; et al.
Journal of Environmental Radioactivity, 68(3), p.249 - 267, 2003/07
Times Cited Count：40 Percentile：62.84(Environmental Sciences)The anthropogenic radionuclides, Sr, Cs and Pu, in the seawater column of the Japan Sea were measured during 1997-2000. The vertical profiles of radionuclide concentrations showed their typical features; exponential decrease with depth for the Sr and Cs and surface minimum - subsurface maximum for the Pu, and there are no substantial differences between the present study and the previous ones. The area-averaged concentrations and the inventories of radionuclides in the Japan Sea are higher than those in the Northwest Pacific Ocean. In the spatial distributions, high inventory area extends and intrudes from the Japan Basin into the Yamato Basin. It is suggested that radionuclides sink by the vertical transport occurring mainly in the Japan Basin then advect into the Yamato Basin after detouring around the Yamato Rise, and finally, they are accumulated in the deep seawater of the Japan Sea.
