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Cs in seabed sediment off the Fukushima coast; Implications from numerical simulationsMisumi, Kazuhiro*; Tsumune, Daisuke*; Tsubono, Takaki*; Tateda, Yutaka*; Aoyama, Michio*; Kobayashi, Takuya; Hirose, Katsumi*
Journal of Environmental Radioactivity, 136, p.218 - 228, 2014/10
Times Cited Count：22 Percentile：54.1(Environmental Sciences)Major controls on spatiotemporal variations of Cs activity in seabed sediments derived from the Fukushima Dai-ichi Nuclear Power Plant accident during the first year after the accident were investigated by using numerical simulations. The model successfully reproduced major features of the observed spatiotemporal variations of Cs activity in sediments. The spatial pattern of Cs in sediments, which mainly reflected the history of Cs activity in the bottom water overlying the sediment and the sediment particle size distribution, became established during the first several months after the accident. Taking Cs activities in sediments in the coastal area and in the vicinity of the power plant into account, increased the simulated total inventory of Cs in sediments off the Fukushima coast to a value on the order of 10
Bq.
Povinec, P. P.*; Livingston, H. D.*; Shima, Shigeki*; Aoyama, Michio*; Gastaud, J.*; Goroncy, I.*; Hirose, Katsumi*; Huynh-Ngoc, L.*; Ikeuchi, Yoshihiro*; Ito, Toshimichi; et al.
Deep Sea Research Part 2: Topical Studies in Oceanography, 50(17-21), p.2607 - 2637, 2003/09
Times Cited Count：100 Percentile：88.9(Oceanography)An international sampling cruise, IAEA'97, was carried out in 1997 in the NW Pacif1c Ocean. The main results of this study are following: (1) The levels of oceanographic parameter showed differences from the historical data, (2) Transuranics water profiles showed typical sub-surface concentration maxima with decrease in concentration by about a factor of 4 from the historical results, deepening their positions by about a factor of 2 and declining the water column inventory by about 20% over 24 years, (3) Sr-90 and Cs-137 data confirmed that the observed changes in concentration profiles have been resulting from the regional water masses circulation, and (4) The concentrations of these radionuclides in surface water after 40 years of their main introduction to the NW Pacific are still showing a latitudinal dependence. The results present the most comprehensive recent study on the distribution of radionuclides in the NW Pacific Ocean with the implications for behaviour of these radionuclides in the water column and physical forcing of water mass circulation over the last 24 years.
Takayama, Katsumi*; Hirose, Naoki*; Kawamura, Hideyuki; Shimizu, Daisuke*; Watanabe, Tatsuro*
no journal, ,
An ocean general circulation model in the Japan Sea has been being developed to reproduce and forecast movement of pollutants at JAEA. It was demonstrated that an assimilation of sea level variation at tide stations along the Japanese coast is effective to reproduce oceanic condition in the nearshore region. In this study, an effect of assimilation of satellite altimeter data, CTD data and tide data is quantitatively surveyed. As a result, it was demonstrated that this assimilation scheme improves the oceanic condition.
Watanabe, Kunio*; Hirose, Katsumi*; Takeuchi, Shinji*; Maekawa, Keisuke
no journal, ,
no abstracts in English
Hirose, Katsumi*; Watanabe, Kunio*; Takeuchi, Shinji*; Maekawa, Keisuke
no journal, ,
no abstracts in English
Maekawa, Keisuke; Watanabe, Kunio*; Hirose, Katsumi*; Takeuchi, Shinji*
no journal, ,
no abstracts in English
Kokubu, Yoko; Momoshima, Noriyuki*; Hirose, Katsumi*; Tagami, Keiko*; Takamiya, Koichi*
no journal, ,
Just after an accident at the Fukushima Daiichi Nuclear Power Plant (FDNPP), data of radionuclides released from the FDNPP were measured for environmental samples by some researchers at individual research institute and university. However a comprehensive database including these data is not constructed now. Working group of the Japan Society of Nuclear and Radiochemical Sciences decided to construct a comprehensive database of data of the radionuclides in environmental samples. This database contains data such as sampling location, sampling method, sampling times, type of measurement system, concentrations of the radionuclides and others in the publications/reports and unpublished issues. Researchers input the data in a dedicated Excel sheet. The working group verifies and registers the data in the database, and then summarizes them in a scientific report.
