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Battulga, B.; Atarashi-Andoh, Mariko; Nakanishi, Takahiro; Koarashi, Jun
Science of the Total Environment, 849, p.157758_1 - 157758_11, 2022/11
Times Cited Count：12 Percentile：49.95(Environmental Sciences)Characterizing plastic-associated biofilms is key to the better understanding of organic material and mineral cycling in the "Plastisphere"-the thin layer of microbial life on plastics. In this study, we propose a new method to extract biofilms from environmental plastics, in order to evaluate the properties of biofilm-derived organic matter through stable carbon (
C) and nitrogen (
N) isotope signatures and their interactions with radionuclides especially radiocesium (
Cs). After ultrasound-assisted separation from the plastics, biofilm samples were successfully collected via a sequence of syringe treatments. Biofilm-derived organic matter samples (14.5-65.4 mg) from four river mouths in Japan showed Cs activity concentrations of 
75 to 820 Bq kg
biofilm (dw), providing evidence that environmental plastics, mediated by developed biofilms, serve as a carrier for Cs in the coastal environment. Significant differences in the (C and N signatures were also obtained for the biofilms, indicating the different sources, pathways, and development processes of biofilms on plastics.
Idomura, Yasuhiro
Europhysics Conference Abstracts (Internet), 45A, 4 Pages, 2021/06
This work presents the impacts of the hydrogen isotope mass and the normalized plasma size on confinement of hydrogen (H) and deuterium (D) plasmas dominated by ion temperature gradient driven turbulence. Numerical experiments of H and D plasmas with ion and electron heating conditions were conducted using the Gyrokinetic Toroidal 5D full- f Eulerian code GT5D. The energy confinement time in the ion heated numerical experiments was almost independent of isotope mass, and the energy confinement was determined mainly by the normalized plasma size or the plasma size divided by the ion gyro radius, indicating an impact of non-local transport. On the other hand, the electron heated numerical experiments showed a clear isotope mass dependency. In addition to the plasma size effect, the isotope mass dependency of the collisional energy transfer from electrons to ions changes the ion heat flux and the turbulence intensity, leading to the degradation of confinement in H plasmas. These results qualitatively agree with the hydrogen isotope scaling in experiments.
Collaborative Laboratories for Advanced Decommissioning Science; Ibaraki University*
JAEA-Review 2019-041, 71 Pages, 2020/03
JAEA-Review-2019-041.pdf:3.38MB
JAEA/CLADS, has been conducting the Center of World Intelligence Project for Nuclear Science/Technology and Human Resource Development (hereafter referred to "the Project") since FY2018. The Project aims at solving problems in nuclear energy field represented by the decommissioning of the Fukushima Daiichi Nuclear Power Station, Tokyo Electric Power Company Holdings, Inc. For this purpose, intelligence has been collected from all over the world, and basic research and human resource development have been promoted by closely integrating/collaborating knowledge and experiences in various fields beyond the barrier of conventional organizations and research fields. Among the adopted proposals in FY2018, this report summarizes the research results of the "Contribution to Risk Reduction in Decommissioning Works by the Elucidation of Basic Property of Radioactive Microparticles". In order to establish the decommissioning procedures (recovery of the melted fuels, decontamination inside the reactors, ensuring the safety of the workers, etc.) of the Fukushima Daiichi Nuclear Power Station, radioactive microparticles released by the accident are an important information source for clarifying what had happened inside the reactors in the course of the accident. The purpose of the present study is to obtain detailed knowledge on the basic properties (particle size, composition, electrical/optical properties, etc.) of the radioactive microparticles, as well as to further elucidate the various properties of the radioactive microparticles including the quantitative evaluation of alpha-ray-emitters, through the Japan-UK synergetic research. Thus, we are conducting research and development that will contribute to the comprehensive works towards the risk reduction in the "decommissioning" plan.
Fusion Technology, 9, p.492 - 498, 1986/00
no abstracts in English
Shollenberger, Q. R.*; Kimura, Yoshiki; Inglis, J. D.*; Lindvall, R.*; Nishiwaki, Hiroki; Yamanaka, Reina; Umino, Yuji*; Hosoi, Masaharu*; Marks, N.*; Kips, R.*; et al.
no journal, ,
Battulga, B.; Atarashi-Andoh, Mariko; Koarashi, Jun
no journal, ,
Plastic debris has been recognized as one of the carriers of hazardous substances in the aquatic ecosystem due to its ubiquitous distribution and potential interaction with pollutants through developed biofilms. In this study, we aimed to extract biofilms from the environmental plastics using a newly developed extraction method and to determine the concentration of radiocesium (Cs) and stable isotope ratios (C and N) in the extracted biofilm samples. Visible plastics were collected from the mouths of coastal rivers in Ibaraki prefecture, Japan, and applied to the extraction procedures. After plastic and biofilm separation with ultrasonication, biofilm samples were collected by the two ways: freeze-drying (15.5-44.4 mg); and freeze-drying after syringe treatment (14.5-65.4 mg). The XRD diffractograms of biofilm samples confirmed that biofilms obtained by freeze-drying only were still heterogeneous and the agglomerations of organic substances, mineral particles, and small microplastics (MPs, 1 mm). The results also demonstrated that biofilm extraction was achieved by syringe treatment separating the mineral and small MPs particles, resulting in homogenous biofilms from the surface of plastics. Preliminarily results of Cs activity concentrations in heterogenous (ranging from 0.22 to 0.54 Bq g) and homogenous (0.82
0.04 Bq g) biofilm samples revealed that MPs serve as a carrier for Cs in the coastal river environment mediated by developed biofilms.
Battulga, B.; Nakayama, Masataka; Atarashi-Andoh, Mariko; Koarashi, Jun
no journal, ,
Plastic debris in the aquatic environment has become a growing concern due to their long-term ecological consequences. The current study is focused on microbial community composition on microplastics (MPs; sizes 5 mm) and characteristics of MP-associated biofilms in coastal river environments of Japan in order to understand the impact of MP-associated biofilms on aquatic organic matter cycling. The aims of the current study are i) extraction and characterization of microbial biofilms on MPs and ii) identification of diversity and composition of microbial communities on MP surfaces and in surrounding surface waters and sediments. The samples were collected from two coastal rivers during 2021-2022 on a seasonal basis. In this study, we proposed a new method to extract biofilms from MPs using ultrasound-assisted syringe treatment for isotopic analysis. Morphotypes of MPs and associated specific microbial taxa as well as seasonal differences were also observed.
