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

https://doi.org/10.1016/j.scitotenv.2020.138098

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.

An Investigation of microbial effect as biofilm formation on radionuclide migration

Yoshikawa, Hideki; Kawakita, Masakazu*; Fujiwara, Kazuhiro*; Sato, Tomofumi; Asano, Takahiro*; Sasaki, Yoshito

Materials Research Society Symposium Proceedings, Vol.1475, p.617 - 622, 2012/06

https://doi.org/10.1557/opl.2012.642

Since it was suggested that the microbes have ability to generate their biofilm in deep underground condition, we examined the effects of biofilm on radionuclide migration scenario. To estimate the effect on matrix diffusion, through diffusion experiment for a biofilm of Desulfovivrio desullfuricans were performed. The effective diffusion coefficient of the biofilm was 10 m/s order which was about ten times smaller than that in free water. It is suggesting that the microbes and biofilm will not interfere with matrix diffusion as a retardation of radionuclide in rock.

Co-precipitation reaction for Ba and Ra into calcite

Yoshida, Yasushi*; Yoshikawa, Hideki; Nakazawa, Toshiyuki*; Sato, Tomofumi*

no journal, , 

To evaluate incorporation behavior of Me larger than Ca in ion radius, co-precipitation experiment were implemented. Partition coefficient is generally used to estimate co-precipitation reaction and this parameter is reported to be affected by precipitation rate of calcite. Therefore, under the condition of variety of R, D for Me larger than Ca into calcite was measured. For trace elements Ra and Ba were used. As a result of experiment Partition coefficient for Ba (or Ra) are decreasing toward the slow R. This tendency is consistent with the reported data. The values of D of Ba and Ra which are low imply those large radius elements are difficult to incorporated into crystal lattice and inclusion is presumably induced by distortion of lattice structure. In addition there is no notable difference of D for Ra and Ba despite difference of radius length. It indicates an extent of inclusion does not depend on a difference of ion radius between Ra and Ba.

Study of deep subsurface microbial community under changing redox conditions using quantitative method

Sasaki, Yoshito; Asano, Takahiro*; Amano, Yuki; Sato, Tomofumi; Iwatsuki, Teruki; Yoshikawa, Hideki

no journal, , 

no abstracts in English

Sorption and desorption of radiocesium to river soils, 1; Soil characterization

Terashima, Motoki; Tachi, Yukio; Sato, Tomofumi; Akagi, Yosuke*; Kawamura, Makoto*; Nakane, Hideji*; Fujiwara, Kenso; Iijima, Kazuki

no journal, , 

no abstracts in English

Modeling of solutes transport at the Horonobe URL, 3; In-situ tracer tests in the rock matrix

Ito, Tsuyoshi*; Tachi, Yukio; Nemoto, Kazuaki*; Sato, Tomofumi*; Takeda, Masaki; Ono, Hirokazu

no journal, , 

To validate the mass transfer model in sedimentary rocks, in-situ tracer test in rock matrix was conducted at rock matrix at 350 m deep drift in the Horonobe URL. The modeling results were evaluated to be reasonable by comparing in-situ and laboratory data.

In situ diffusion experiment in mudstone at the Horonobe URL; Comparative study between in situ and laboratory tests

Tachi, Yukio; Takeda, Masaki; Ono, Hirokazu; Ito, Tsuyoshi*; Sato, Tomofumi*; Nemoto, Kazuaki*

no journal, , 

Spatial distribution of biofilm-forming Archaea in the deep sedimentary rock environment of the Horonobe area, Hokkaido, Japan

Amano, Yuki; Beppu, Hikari*; Sato, Tomofumi*; Mochizuki, Akihito; Thomas, B. C.*; Banfield, J. F.*

no journal, ,