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Terashima, Motoki; Endo, Takashi*; Miyakawa, Kazuya
Journal of Nuclear Science and Technology, 57(4), p.380 - 387, 2020/04
Times Cited Count：2 Percentile：21.58(Nuclear Science & Technology)Kimuro, Shingo*; Kirishima, Akira*; Nagao, Seiya*; Saito, Takumi*; Amano, Yuki; Miyakawa, Kazuya; Akiyama, Daisuke*; Sato, Nobuaki*
Journal of Nuclear Science and Technology, 55(5), p.503 - 515, 2018/05
Times Cited Count：7 Percentile：58.07(Nuclear Science & Technology)no abstracts in English
Yamashita, Yuji*; Saito, Takumi
Journal of Environmental Chemical Engineering, 3(4), p.3024 - 3029, 2015/12
Humic substances are natural organic matters with heterogeneity in the size distribution and composition of there functional groups. In this study, the effects of organic acid, which are often used as pH buffering agents, on the size of a humic substance and size-dependent binding of metal ions on the humic substance were investigated by flow-field flow fractionation (Fl-FFF). Comparing the three organic acids, Tris, MES, and MOPS, the size of purified Aldrich humic acid (PAHA) changed in the presence of Tris and MES, suggesting that the interaction with these organic acid modulated the molecular structure of PAHA; on the other hand, MOPS hardly affect the size of PAHA. Size-dependent binding of europium (Eu
) and uranium (UO
) were also studied by Fl-FFF in the presence of MOPS. The binding of these metal ions were not homogeneous with respect to the size of PAHA; they exhibited high affinity to PAHA fractions with 5 nm hydrodynamic diameter.
Saito, Takumi; Terashima, Motoki; Aoyagi, Noboru; Nagao, Seiya*; Fujitake, Nobuhide*; Onuki, Toshihiko
Environmental Science; Processes & Impacts, 17(8), p.1386 - 1395, 2015/08
Times Cited Count：9 Percentile：32.46(Chemistry, Analytical)The deep groundwater HSs were different from surface HSs, having high aliphaticities, sulfur contents, and small molecular sizes. The amounts of their acidic functional groups were comparable to or slightly larger than those of surface HSs; however, the magnitude of Cu binding to the deep groundwater HSs was smaller. The NICA-Donnan model attributed this to the binding of Cu to chemically homogeneous carboxylic-type sites via mono-dentate coordination at relatively low pH. The binding mode tended to shift to multi-dentate coordination with carboxylic-type and probably more heterogeneous alcoholic hydroxide-type groups at higher pH. This study shows the particularity of the deep groundwater HSs in terms of their physicochemical and ion-binding properties, compared with surface HSs.
Ueda, Masato; Sakamoto, Yoshiaki*
Genshiryoku Bakkuendo Kenkyu, 12(1-2), p.31 - 39, 2006/03
no abstracts in English
Ni migration through crushed rock mediaTanaka, Tadao; Sakamoto, Yoshiaki; Mukai, Masayuki; Maeda, Toshikatsu; Nakayama, Shinichi
Radiochimica Acta, 92(9-11), p.725 - 729, 2004/12
Times Cited Count：1 Percentile：10.03(Chemistry, Inorganic & Nuclear)Migration experiments of Ni for crushed rocks, granite and tuff, were performed under the coexistent condition with a humic acid and a fulvic acid of 0-30 mg/l in concentration, which are Nordic humic substances supplied from International Humic Substance Society. Migration experiments of Ni had been performed by a column system, to investigate migration behavior of Ni through a column packed crushed rock. The Ni concentration in the effluent passed through the column was corresponding to the fractional percentage of Ni complexing with humic substance in influent solution. This result suggests that the Ni complexing with humic substance in influent solution was flowed out from the column without any effective interactions with the rock media. The migration behavior of Ni could be expressed by a migration model taking account of the complexation kinetics of Ni with humic substance in the aqueous phase.
Tanaka, Tadao; Sakamoto, Yoshiaki; Sawada, Hiroshi; Ogawa, Hiromichi
JAERI-Conf 2003-010, p.134 - 141, 2003/09
We have performed migration experiments of Np(V) and Am(III) for crushed granite, under the coexistent condition with humic acid substance. As for Np, the periodical concentration changes in the breakthrough curve and the migration velocity of Np passed through the column were not affected by the coexistence of the humic substance. As for Am, on the other hand, the periodical concentration changes in the breakthrough curve were affected by the humic substance concentration. The migration behavior of Am passed through the present column system could be expressed by a migration model taking account of the non-equilibrium state.
Tanaka, Tadao; Sakamoto, Yoshiaki; Ogawa, Hiromichi
Genshiryoku Bakkuendo Kenkyu, 9(1), p.29 - 34, 2002/09
To obtain structural information on functional groups of humic substances complexing with metal ions, infrared (IR) spectral analysis of the humic substances dissolving in aqueous solutions has been studied by ATR (Attenuated Total Reflection) method. By using the ATR method, IR spectral shifts of humic substance due to complexation with metal ions were observed. The observation provided with information on complexation kinetics, and on characteristics of functional groups depending on solvent properties, such as pH and solute concentrations. These information was difficult to be obtained by conventional FTIR spectroscopy using powdered humic substances. The obtained results show that IR spectral shifts on the functional groups of the humic substances complexed with metal ions could be possibly characterized 
by using the ATR-FTIR spectroscopy.
Matsunaga, Takeshi; Nagao, Seiya*; Takeda, Seiji; Ueno, Takashi; Amano, Hikaru
Dai-43-Kai Kankyo Hoshano Chosa Kenkyu Seika Rombun Shorokushu (Heisei-12-Nendo), p.49 - 50, 2002/03
no abstracts in English
Fukushima, Masami*; Tatsumi, Kenji*; Nagao, Seiya
Environmental Science & Technology, 35(18), p.3683 - 3690, 2001/09
Times Cited Count：135 Percentile：92.77(Engineering, Environmental)no abstracts in English
Imanaka, Masayo*; Nagao, Seiya; Nakaguchi, Yuzuru*; Yamaguchi, Yoshitaka*; Suzuki, Yasuhiro*; Murakami, Masahiro*; Hiraki, Keizo*
Proceedings of International Conference on the Biogeochemistry of Trace Elements (ICOBTE2001), P. 662, 2001/00
no abstracts in English
Sakamoto, Yoshiaki; Nagao, Seiya; Ogawa, Hiromichi; Rao, R. R.*
Radiochimica Acta, 88(9-11), p.651 - 656, 2000/09
Times Cited Count：11 Percentile：59.85(Chemistry, Inorganic & Nuclear)no abstracts in English
Suzuki, Yasuhiro*; Nakaguchi, Yuzuru*; Hiraki, Keizo*; Nagao, Seiya; *; *
Chikyu Kagaku, 32, p.21 - 30, 1998/00
no abstracts in English
Nagao, Seiya; Suzuki, Yasuhiro*; Nakaguchi, Yuzuru*; ; Hiraki, Keizo*
Bunseki Kagaku, 46(5), p.335 - 342, 1997/00
no abstracts in English
Amano, Hikaru; Watanabe, Miki*; Onuma, Yoshikazu*; Ueno, Takashi; Matsunaga, Takeshi; N.D.Kuchma*
The Role of Humic Substances in the Ecosystems and in Environmental Protection, 0, p.709 - 716, 1997/00
no abstracts in English
Amano, Hikaru; Matsunaga, Takeshi; Ueno, Takashi; Onuma, Yoshikazu*; Watanabe, Miki*; Yanase, Nobuyuki; Nagao, Seiya; Sukhoruchkin, A. K.*
Proceedings of 5th International Scientific and Technical Conference on the Problems of Liquidation of Chernobyl Accident Consequences, P. 74, 1996/00
no abstracts in English
Sr in a coastal sandTanaka, Tadao; Mukai, Masayuki;
Hoshasei Haikibutsu Kenkyu, 1(2), p.169 - 176, 1995/05
no abstracts in English
Saito, Takumi; Terashima, Motoki; Onuki, Toshihiko
no journal, ,
Redox properties of humic substances extracted from deep sedimentary groundwater was investigated by cyclic voltammetry and bulk electrolysis with a mediator organic molecule. Reversible current-potential curves were observed with the mediator, although electrode reaction of humic substances are slow in general. The redox capacities of various humic substances exhibited positive correlation with their aromaticity; those of deep groundwater humic substances were appreciably smaller than those of surface humic substances.
Ito, Yuki*; Oyama, Takahiro*; Miyakawa, Kazuya; Sasamoto, Hiroshi
no journal, ,
no abstracts in English
Terashima, Motoki; Amano, Yuki
no journal, ,
Effects of microbial activity and coexisting cations on association of selenium (Se) with humic substance (HS) in deep groundwater were investigated by means of incubation experiments, DAX-8 extraction, and size-exclusion chromatography combined with UV-Vis and ICP-MS detections (SEC-ICP-MS). Selenite added into the groundwater was effectively reduced to elemental Se(0) by microbial activity stimulated by a nutrient. The DAX-8 extraction showed the existence of Se fraction that is extracted with HS. The SEC-ICP-MS analysis for alkaline extracts of the DAX-8 showed that the chromatogram of Se, HS and Fe are well corresponded each other, and were obtained regardless of the sterilization of groundwater. These indicate the possibility that Se can associate with HS in deep groundwater via the interaction with Fe.
