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Journal Articles

Key factors controlling radiocesium sorption and fixation in river sediments around the Fukushima Daiichi Nuclear Power Plant, 1; Insights from sediment properties and radiocesium distributions

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:3 Percentile:26.45(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.

Journal Articles

Determination of humic substances in deep groundwater from sedimentary formations by the carbon concentration-based DAX-8 resin isolation technique

Terashima, Motoki; Endo, Takashi*; Miyakawa, Kazuya

Journal of Nuclear Science and Technology, 57(4), p.380 - 387, 2020/04

 Times Cited Count:0 Percentile:100(Nuclear Science & Technology)

Journal Articles

Europium binding to humic substances extracted from deep underground sedimentary groundwater studied by time-resolved laser fluorescence spectroscopy

Saito, Takumi*; Aoyagi, Noboru; Terashima, Motoki

Journal of Nuclear Science and Technology, 54(4), p.444 - 451, 2017/04

 Times Cited Count:2 Percentile:66.26(Nuclear Science & Technology)

Humic substances (HSs) are ubiquitous in various environments including deep underground and play an important role in the speciation and mobility of radionuclides. The binding of Eu$$^{3+}$$, a chemical homologue of trivalent actinide ions, to HSs isolated from sedimentary groundwater at -250 m below the surface was studied by time-resolved laser fluorescence spectroscopy combined with parallel factor analysis (PARAFAC) as a function of pH and salt concentration. PARAFAC modeling reveals the presence of multiple factors that corresponds to different Eu$$^{3+}$$ species. These factors resemble those observed for Eu$$^{3+}$$ binding to HSs from surface environments; however, detailed comparison shows that there are some particularities in Eu$$^{3+}$$ binding to the deep groundwater HSs. The distribution coefficients ($$K_{rm d}$$) of Eu$$^{3+}$$ binding to the HSs calculated from the PARAFAC modeling exhibits a rather strong salt effect. At 0.01 M NaClO$$_{4}$$ the $$K_{rm d}$$ values are relatively large and comparable to those to the surface HSs; they are decreaed at 0.1 M NaClO$$_{4}$$ by more than an order of the magnitude. The $$K_{rm d}$$ values are larger for humic acid fraction of the deep underground HSs than fulvic acid over the entire range of pH and salt concentration investigated in this study.

Journal Articles

Physicochemical and ion-binding properties of highly aliphatic humic substances extracted from deep sedimentary groundwater

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:5 Percentile:74.36(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$$^{2+}$$ binding to the deep groundwater HSs was smaller. The NICA-Donnan model attributed this to the binding of Cu$$^{2+}$$ 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.

Journal Articles

Europium-binding abilities of dissolved humic substances isolated from deep groundwater in Horonobe area, Hokkaido, Japan

Terashima, Motoki; Nagao, Seiya*; Iwatsuki, Teruki; Fujitake, Nobuhide*; Seida, Yoshimi*; Iijima, Kazuki; Yoshikawa, Hideki

Journal of Nuclear Science and Technology, 49(8), p.804 - 815, 2012/08

 Times Cited Count:10 Percentile:31.99(Nuclear Science & Technology)

Journal Articles

Sorption and diffusion of Eu in sedimentary rock in the presence of humic substance

Seida, Yoshimi; Terashima, Motoki; Tachi, Yukio; Iijima, Kazuki; Nakazawa, Toshiyuki*; Yamada, Norikazu*; Yui, Mikazu

Radiochimica Acta, 98(9-11), p.703 - 709, 2010/11

Diffusion and sorption behaviors of Eu in sedimentary rock were investigated in the presence of humic substance in the present study. Sedimentary rock obtained from Horonobe URL test site in Hokkaido, Japan, (accessible pore diameter is around several to several ten nanometer) was used. The Diffusion behaviors of Eu were examined based on reservoir depletion method coupled with analysis of inner distribution of the radioactive elements in the rock. Time sequence of concentration of each radioactive element as well as the humic substance in the reservoir was obtained as a function of concentration and molecular size of humic substance. Coexistence of humic substance reduced the depletion of Eu in the reservoir, indicating complexation between the radioactive elements and the humic substance. On the contrary, obvious decrease of humic substance in the reservoir was not observed in the system. This observation suggests that the radioactive elements became hard to diffuse into the sedimentary rock due to an increase of their size through complexation with the humic substance. The sorption of Eu was reduced with increase of the humic substance although the sorption of the humic substance was not influenced by the existence of Th or Eu. The diffusion and sorption of Eu were found to be reduced in the presence of humic substance.

JAEA Reports

JAEA thermodynamic database for performance assessment of geological disposal of high-level radioactive and TRU wastes

Kitamura, Akira; Fujiwara, Kenso; Doi, Reisuke; Yoshida, Yasushi*; Mihara, Morihiro; Terashima, Motoki; Yui, Mikazu

JAEA-Data/Code 2009-024, 84 Pages, 2010/03

JAEA-Data-Code-2009-024.pdf:2.84MB

A thermodynamic database was established to develop a thermodynamic database for performance assessment of geological disposal of high-level and TRU wastes. Twenty-four elements (actinides, fission products and their daughters) which are of importance for the performance assessment of geological disposal have been selected. The fundamental plan was in principle based on the guidelines established by the Nuclear Energy Agency in the Organisation for Economic Co-operation and Development (OECD/NEA). Additional unique guidelines were established due to a requirement from the performance assessment to select tentative thermodynamic values obtained from chemical analogues and/or models for elements with insufficient thermodynamic values. Selected thermodynamic data were compiled for geochemical calculation programs.

Oral presentation

Eu(III) binding abilities of dissolved humic substances isolated from deep groundwater in Horonobe area, Hokkaido, Japan

Terashima, Motoki; Seida, Yoshimi; Iwatsuki, Teruki; Iijima, Kazuki; Yoshikawa, Hideki; Yui, Mikazu; Nagao, Seiya*

no journal, , 

Eu(III) binding abilities of dissolved humic substances (HSs), which were extracted from deep groundwater in the Horonobe Underground Research Center, Hokkaido, Japan, were investigated by fluorescence quenching technique. In the synthetic groundwater condition, the fluorescence quenching due to the binding with Eu(III) was not observed for the groundwater HSs, while that was observed for the Aldrich humic acid (HA). This result indicates that the binding ability of the groundwater HSs are different from that of Aldrich HA. Based on structural characteristics of the groundwater HSs, the differences in the binding ability are discussed.

Oral presentation

Eu(III) binding properties of dissolved humic substances isolated from deep groundwater in Horonobe area, Hokkaido, Japan

Terashima, Motoki; Nagao, Seiya*; Iwatsuki, Teruki; Sasaki, Yoshito; Seida, Yoshimi; Yoshikawa, Hideki

no journal, , 

no abstracts in English

Oral presentation

In situ experiment for redox buffer capacity in the subsurface environment

Amano, Yuki; Nanjo, Isao; Iwatsuki, Teruki; Sasaki, Yoshito; Asano, Takahiro; Terashima, Motoki; Nagaoka, Toru*; Nakamura, Takamichi*; Yoshikawa, Hideki; Aoki, Kazuhiro

no journal, , 

In-situ experiment of redox reaction was conducted to assess the redox buffur capacity of water-rock-microbes system in the subsurface environment at 140 m depth of Horonobe Underground Research Laboratory. Dissolved oxygen was injected into a borehole, and the physico-chemical parameters (i.e. pH, ORP, DO, EC, etc.) and geochemical composition, microbial cell number, and microbial community structure were monitored continuously during the groundwater circulation. DO concentration could not detected after 10 hours from the injection. The concentration of Fe(II) was decreased with time, then the injected oxygen could be consumed by Fe(II). The rate of oxygen consumption during the experiment was 9.64 mg/L/day. The Eh value become stable at -208 mV after 5 days, then it showed that the reducing condition would be recovered quickly after closed condition.

Oral presentation

Application of NICA-Donnan model for the simulation of Eu solubility in the presence of deep groundwater humic substances

Terashima, Motoki; Seida, Yoshimi*; Okazaki, Mitsuhiro; Iwatsuki, Teruki; Iijima, Kazuki; Yui, Mikazu

no journal, , 

no abstracts in English

Oral presentation

Application of NICA-Donnan model to modelling of Eu(III) solubility in the presence of deep groundwater humic substances

Terashima, Motoki; Okazaki, Mitsuhiro; Iijima, Kazuki; Yui, Mikazu

no journal, , 

no abstracts in English

Oral presentation

Sorption of Eu in the ternary system of Eu/groudwater humic substances/sedimentary rock

Terashima, Motoki; Okazaki, Mitsuhiro; Iijima, Kazuki; Yoshikawa, Hideki

no journal, , 

no abstracts in English

Oral presentation

Oral presentation

Effect of humic substances on the sorption and diffusion of Eu(III) in sedimentary rock

Terashima, Motoki; Tachi, Yukio; Saito, Takumi*; Iijima, Kazuki; Shimoda, Satoko*; Nakazawa, Toshiyuki*; Yoshikawa, Hideki

no journal, , 

no abstracts in English

Oral presentation

Investigation for colloids in the groundwater of Horonobe URL, 1; Characterization of colloids in the groundwater by using ultra filtration

Amano, Yuki; Amamiya, Hiroki; Murakami, Hiroaki; Iwatsuki, Teruki; Terashima, Motoki; Mizuno, Takashi; Kirishima, Akira*; Kuno, Atsushi*; Sasaki, Takayuki*; Kubota, Takumi*; et al.

no journal, , 

no abstracts in English

Oral presentation

Method for developing NICA-Donnan model parameters of groundwater humic substances

Terashima, Motoki; Saito, Takumi*; Iijima, Kazuki; Yoshikawa, Hideki

no journal, , 

no abstracts in English

Oral presentation

Assessing the effect of humic substances on migration of radionuclides in geological disposal system

Terashima, Motoki; Saito, Takumi*; Okazaki, Mitsuhiro*; Tachi, Yukio; Iijima, Kazuki

no journal, , 

no abstracts in English

Oral presentation

Sorption and desorption of radioactive cesium to soil clay fraction; Effect of soil organic matter

Terashima, Motoki; Tachi, Yukio; Fujiwara, Kenso; Iijima, Kazuki; Shimoda, Satoko*; Akagi, Yosuke*; Kato, Hiroyasu*

no journal, , 

no abstracts in English

Oral presentation

Disorption of cesium from soil of river and aggregation of cray in Fukushima coastal area

Fujiwara, Kenso; Iijima, Kazuki; Terashima, Motoki; Tachi, Yukio

no journal, , 

no abstracts in English

42 (Records 1-20 displayed on this page)