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Mitsuguchi, Takehiro; Okabe, Nobuaki*; Yokoyama, Yusuke*; Yoneda, Minoru*; Shibata, Yasuyuki*; Fujita, Natsuko; Watanabe, Takahiro; Kokubu, Yoko
Journal of Environmental Radioactivity, 235-236, p.106593_1 - 106593_10, 2021/09
Times Cited Count:5 Percentile:32.67(Environmental Sciences)For a contribution to developing the usage of iodine-129 (I) as a tracer of deep-seated fluid, I/I and C were measured for annual bands (AD 1931-1991) of a modern coral collected from Northwestern Australia; the measurements were performed using the JAEA-AMS-TONO-5MV for I/I and an AMS facility of the University of Tokyo for C. Results indicate that both I/I and C distinctly increase from 1950s. The C increase can be ascribed to atmospheric nuclear tests, while the I/I increase is due to nuclear-fuel reprocessing as well as atmospheric nuclear tests. These results are in good agreement with previous studies, indicating that the I/I measurement by JAEA-AMS-TONO-5MV has been further developed.
Nagao, Seiya*; Irino, Tomohisa*; Aramaki, Takafumi*; Ikehara, Ken*; Katayama, Hajime*; Otosaka, Shigeyoshi; Uchida, Masao*; Shibata, Yasuyuki*
Radiocarbon, 52(3), p.1068 - 1077, 2010/08
Times Cited Count:0 Percentile:0.01(Geochemistry & Geophysics)This study discusses the effects of flooding on the spatial distribution of organic matter on the shelf region of off the Saru River, southern part of Hokkaido, Japan, on the basis of the C and C values. Surface sediments on the shelf were collected in August 2007, one year after the severe flood in 2006. Suspended particles and sediment of the Saru River were also collected in August 2007 and 2008. The C values of organic matter in the shelf sediments ranged from -665 to -77 per mil. The silt and clay sediments had C values of -240 to -77 per mil, but the sandy sediments ranged from -665 to -388 per mil. The values of particulate organic carbon in the Saru River are -292 to -247 per mil at normal flow conditions. These results indicate that surface soil with relatively older organic matter is deposited on the shelf region by the flooding event, and freshly-produced organic matter in sea surface is deposited after the flooding.
Kumamoto, Yuichiro*; Aramaki, Takafumi*; Watanabe, Shuichi*; Yoneda, Minoru*; Shibata, Yasuyuki*; Togawa, Orihiko; Morita, Masatoshi*; Shitashima, Kiminori*
Journal of Oceanography, 64(3), p.429 - 441, 2008/06
Times Cited Count:11 Percentile:25.18(Oceanography)In 1995 and 2000, radiocarbon ratio (C) of total dissolved inorganic carbon was measured in the Japan Sea, a semi-closed marginal sea in the western North Pacific, where deep and bottom waters are formed in itself. Compiling them with historical radiocarbon data in the Japan Sea, temporal and spatial variations of the radiocarbon in the bottom water below 2000 m depth were elucidated. C in the bottom waters in the western Japan and Yamato Basins increased by about 20 ‰ between 1977/79 and 1995 and did not changed between 1995 and 1999/2000, suggesting penetration of surface bomb-produced radiocarbon into the bottom waters due to bottom ventilation in the earlier period and stagnation of the bottom ventilation in the following period, respectively. In the eastern Japan Basin, the bottom C increased by about 10 ‰ between 1977/79 and 2002, suggesting less ventilation of the bottom water in the basin. The temporal changes of the radiocarbon, tritium, and dissolved oxygen suggest sporadic occurrences of the bottom ventilation between 1979 and 1984 and its stagnation between 1984 and 2004 in the eastern Japan and Yamato Basins. The former is probably due to spreading of a newly ventilated bottom water in the western Japan Basin in the severe winter of 1976-1977 along the abyssal circulation in the Japan Sea. The latter does not conflict with temporal changes of bomb-produced Cs and chlorofluorocarbon-11 in the bottom water.
Iida, Kunihiro*; Shibata, Katsuyuki; Ueda, Shuzo; Kobayashi, Hideo*; Higuchi, Makoto*; *; *; *; *; *; et al.
JAERI-M 91-224, 88 Pages, 1992/01
no abstracts in English
Nagao, Seiya*; Aramaki, Takafumi*; Irino, Tomohisa*; Uchida, Masao*; Shibata, Yasuyuki*; Togawa, Orihiko
no journal, ,
no abstracts in English