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Tachi, Yukio; Sato, Tomofumi*; Akagi, Yosuke*; Kawamura, Makoto*; Nakane, Hideji*; Terashima, Motoki; Fujiwara, Kenso; Iijima, Kazuki
Science of the Total Environment, 724, p.138098_1 - 138098_11, 2020/07
Times Cited Count：13 Percentile：57.17(Environmental Sciences)To understand and predict radiocesium transport behaviors in the environment, highly contaminated sediments from Ukedo and Odaka rivers around the Fukushima Daiichi Nuclear Power Plant were investigated systematically focusing on key factors controlling radiocesium sorption and fixation, including particle size, clay mineralogy and organic matter.
Tachi, Yukio; Sato, Tomofumi*; Takeda, Chizuko*; Ishidera, Takamitsu; Fujiwara, Kenso; Iijima, Kazuki
Science of the Total Environment, 724, p.138097_1 - 138097_10, 2020/07
Times Cited Count：9 Percentile：43.42(Environmental Sciences)To understand and predict radiocesium transport behaviors in the environment, sorption and fixation behaviors of radiocesium on river sediments from Ukedo and Odaka rivers around the Fukushima Daiichi Nuclear Power Plant were investigated systematically focusing on Cs sorption and fixation mechanisms and their relationship with Cs concentrations and sediment properties including clay mineralogy and organic matter.
Cs fluvial export from a forest catchment evaluated by stable carbon and nitrogen isotopic characterization of organic matterMuto, Kotomi; Atarashi-Andoh, Mariko; Koarashi, Jun; Takeuchi, Erina; Nishimura, Shusaku; Tsuzuki, Katsunori; Matsunaga, Takeshi*
Journal of Radioanalytical and Nuclear Chemistry, 314(1), p.403 - 411, 2017/10
Times Cited Count：16 Percentile：83.87(Chemistry, Analytical)Fluvial export of particulate and dissolved Cs was investigated to reveal its sources and transfer mechanisms in a broadleaved forest catchment using a continuous collection system. The finest size fraction (
75
m), consisting of decomposed litter and surface mineral soil, was the dominant fraction in the particulate Cs load, although the contribution of coarser size fractions increased during high water discharge in 2014. The dissolved Cs originated from the decomposition of Cs-contaminated litter. Temporal changes in Cs distribution in the litter-mineral soil system indicated that the dissolved Cs load will be moderated in several years, while particulate Cs load has the potential to continue for a long time.
Matsunaga, Takeshi; Nagao, Seiya*; Ueno, Takashi; Takeda, Seiji; Amano, Hikaru; Tkachenko, Y.*
Applied Geochemistry, 19(10), p.1581 - 1599, 2004/10
Times Cited Count：35 Percentile：55.27(Geochemistry & Geophysics)The association of dissolved 
Sr, 
Pu and 
Am with natural colloids was investigated in surface waters in the Chernobyl nuclear accident area by means of ultrafiltration. Results suggest that Pu and Am isotopes were preferentially associated with dissolved humic substances (HS) of high molecular size. A model calculation of the complexation of Pu and Am with HS also supported the above. This study has expanded our understanding of the general role of natural organic colloids in dictating the chemical form of actinides in the surface aquatic environment.
Nagao, Seiya; Sakamoto, Yoshiaki; Tanaka, Tadao; Ogawa, Hiromichi
Proceedings of OECD/NEA Workshop on Evaluation of Speciation Technology, p.181 - 188, 1999/00
no abstracts in English
Nihon Denshi Nyusu, 27(1-2), p.12 - 17, 1987/02
no abstracts in English
Yu, Q.; Onuki, Toshihiko; Tanaka, Kazuya*; Kozai, Naofumi; Yamasaki, Shinya*; Sakamoto, Fuminori; Tani, Yukinori*
no journal, ,
REEs were accumulated by MnO
during oxidation of Mn(II) to MnO by manganese oxidizing fungus. In the presence of citate-Na, adsorption of REE was lowered than that without citrate. REE pattern in the solution showed positive anomaly in Ce, indicating that Ce(IV) was associated with organic materials excreted from the cells.
Saito, Takumi*; Nishi, Shusaku*; Toda, Kanako*; Miyakawa, Kazuya; Amano, Yuki
no journal, ,
no abstracts in English
Saito, Takumi*; Nishi, Shusaku*; Sato, Hayato*; Miyakawa, Kazuya
no journal, ,
Dissolved organic matters (DOMs) play an important role for the fate of pollutants in surface and subsurface environments. For migration of radionuclides, the binding to DOMs modulates their aqueous speciation, reduce the adsorption on rock surface, and even enhance their transport, compared with non-sorbing tracers. The origin of DOMs in surface environments have been studied for decades and mechanistic models are proposed, which can describe ion-binding to major fractions DOMs (i.e. humic and fulvic fractions) over a wide range of environmental conditions. Nevertheless, our understanding on deep groundwater DOMs remains limited, and it is still disputable if model parameters calibrated for surface DOMs can be applied for their counterparts in deep subsurface environments. This study aims to reveal the origin of different DOM components in deep sedimentary groundwater and their ion-binding properties by fluorescence spectroscopy and high-resolution mass spectrometry. The results of both techniques are processed and correlated by multivariate analysis to find different DOM components and pursue their molecular characteristics. In the conference, we will present various molecular metrices describing the EEM components with the help of an advanced multivariate technique, which allows us to simultaneously process both the entire data sets of EEM and FT-ICR-MS data, consisting of the different data dimensions.
Saito, Takumi*; Nishi, Shusaku*; Sato, Hayato*; Miyakawa, Kazuya; Amano, Yuki; Beppu, Hikari*
no journal, ,
no abstracts in English
