Author: Takumi.Saito

Article accepted by the Cement journal

An article by Dr. Toda has been accepted in the Cement journal. The title is “Effects of lignosulfonate on synthesis products of the pozzolanic reaction”. Toda, K., Minato, D., Saito, T., Kikuchi, R., Otake, T., Sato, T., “Effects of lignosulfonate on synthesis products of the pozzolanic reaction”, Cement, in press (2022).

Article accepted by the PCCP journal

An article by our Ph.D. student, Mr. Murota, has been accepted in Phys. Chem. Chem. Phys. The title is “Pore size effects on surface charges and interfacial electrostatics of mesoporous silicas”. Murota, K.*, Saito, T., “Pore size effects on surface charges and interfacial electrostatics of mesoporous silicas”, Phys. Chem. Chem. Phys., in press (2022).

Student graduation

Shusaku, who is involved in the research on “Origin of natural organic matters in deep underground environments” through his undergraduate and master-course research, has juste graduated. The photo was take in the graduation ceremony.

New staff member has joined

A new member has joined in the group. Ms. Kanako Toda, assistant professor. She’ll be involved in researches on materials for waste disposal.

Student graduation

Keita, who is involved in the research on application of machine learning on radionuclide migration in discrete fracture network, has juste graduated from the master course. The photo was take in the graduation ceremony on Mar. 19.

Desorption mechanisms of cesium from illite and vermiculite

Background Vast areas of the eastern part of Japan have been contaminated by a short-lived radioisotope of cesium (Cs), 137Cs, whose half-life is 30.1 years, from the accident of the Fukushima Dai-ichi Nuclear Power Plant in 2011. Most of contaminated soils in residential areas have been stripped and gathered for future disposal. On the other hand, air dose rates in forests are still high. Understanding the behaviors of Cs+ in soils is thus crucial for the safety assessments of the disposal of contaminated soil in future and the evaluation of long-term exposure of residents living near forest areas. It is known that Cs+ is strongly sorbed to micaceous minerals. However, the desorption of Cs+ at a trace sorption level with time in the presence of different salt ions is not well understood. In this study, we conducted long-term sorption and desorption experiments of Cs+ with illite and vermiculite, which are micaceous minerals, at room temperature to study the effects of sorption time and co-existing cations on the desorption. Method A small amount of Cs+ (50 nM Cs+ spiked with 900 Bq 137Cs) was sorbed to the illite and vermiculite in the presence of 1 mM K+ or Ca2+, or 1 mM K+ and 100 mM Ca2+ over 8 weeks, which was then desorbed in the presence of Prussian blue (PB) […]

Article accepted by the Applied Geochemistry journal

An article by our Ph.D. student, Mr. Murota, has been accepted in Appl. Geochem. The title is “Desorption mechanisms of cesium from illite and vermiculite”. Murota, K.*, Tanoi, K., Ochiai, A., Utsunomiya, T., Saito, T., “Desorption mechanisms of cesium from illite and vermiculite”, Appl. Geochem.,  in press (2020).

AESJ fellow prize for Mr. Fukuoka

Mr. Fukuoka, who has graduated from our lab and is now working in Tokyo Electric Power Company, is recieve a fellow prize of the Atomic Energy Society Japan. He dis a research on so-called DGT (diffusive gradient in thin film) for environmental behaviors of radioacitive cesium in Fukushima prefecture.

Evaluation of labile fraction of radioactive Cs by diffusive gradients in thin films (DGT)

Background A large area of Fukushima Prefecture was contaminated by radioactive nuclides, radioactive cesium in particular, released by the accident of the Fukushima Daiichi nuclear power plants in Mar., 2011. Most of residential area has been decontaminated by now; nevertheless, a large part of forests Environmental behaviors of radioactive Cs is crucial to predict long-term changes of its distribution in soil or river environments. It is known that Cs is selectively bound to micaceous minerals in nature and inert for chemical exchange reactions. Nevertheless, dynamics of labile fractions of Cs in a given environment if any must play an important role for its environmental behaviors, as it directly contributes to the mobility and bioavailability of Cs. In this study, we perform in-situ evaluation of the labile Cs in soil and aqueous environments of Fukushima Prefecture by diffusive gradients in thin films (DGT), which is a technique designed for the lability measurement of trace elements in nature. Research contents Two types of DGT devices, one for aqueous environments and the other for soil environments, were developed and their applicability for environments have been tested by laboratory experiments. With the developed devices we have revealed that the labile fractions of radioactive Cs In river environments exceeds the dissolved ones, suggesting that the desorption of Cs from suspended particles modulates its behaviors in […]