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Journal Articles

Biofilm-mediated interactions between plastics and radiocesium in coastal environments

Battulga, B.; Nakanishi, Takahiro; Atarashi-Andoh, Mariko; Otosaka, Shigeyoshi*; Koarashi, Jun

Environmental Science and Pollution Research, 31, p.60080 - 60092, 2024/10

https://doi.org/10.1007/s11356-024-35164-y

A ubiquitous distribution of plastic debris has been reported in aquatic and terrestrial environments; however, the interactions between plastics and radionuclides and the radioactivity of environmental plastics remain largely unknown. Here, we characterize biofilms developing on the surface of plastic debris to explore the role of plastic-associated biofilms as an interaction medium between plastics and radiocesium ( $^{137}$ Cs) in the environment. Biofilm samples were extracted from plastics (1-50 mm in size) collected from two contrasting coastal areas in Japan. The radioactivity of plastics was estimated based on the $^{137}$ Cs activity concentration of the biofilms and compared seasonally with surrounding environmental samples (i.e., sediment and sand). $^{137}$ Cs traces were detected in biofilms with activity concentrations of 21-1300 Bq kg $^{-1}$ biofilm (dry weight), corresponding to 0.04-4.5 Bq kg $^{-1}$ plastic (dry weight). Our results reveal the interaction between $^{137}$ Cs and plastics and provide evidence that organic and mineral components in biofilms are essential in $^{137}$ Cs retention in environmental plastics.

Journal Articles

Numerical reproduction of the seasonal variation in dissolved uranium in Lake Biwa

Saito, Tatsuo; Yamazawa, Hiromi*; Mochizuki, Akihito

Journal of Environmental Radioactivity, 255, p.107035_1 - 107035_14, 2022/12

https://doi.org/10.1016/j.jenvrad.2022.107035

Times Cited Count：0 Percentile：0.00(Environmental Sciences)

The seasonal variation of dissolved U (DU) in Lake Biwa was reproduced by the following model and parameter research. The introduced models are the water-DU mass balance, and the ion exchange between UO $_{2}$ $^{2+}$ and H $^{+}$ on the lakeshore soil. The optimized parameters were the CEC of the lakeshore, TU as the sum of DU and AU (soil adsorbed U), kads and kdes as the first order reaction rate coefficients during rapid soil adsorption and desorption of U, respectively. Tabulated by the chemical equilibria constituting DU and analyzed the contribution of each chemical species, it is shown that the seasonal variation of DU is caused by the seasonal variation of pH. A correction to the ion-exchange equilibrium to shift to first order rate reaction only when the daily AU ratio increased above kads or decreased below kdes, improved the reproducibility of DU measurements and reproduced the delay of the DU peak from the pH peak.

Journal Articles

Development of spin-contrast-variation neutron reflectometry

Kumada, Takayuki; Akutsu, Kazuhiro*; Oishi, Kazuki*; Morikawa, Toshiaki*; Kawamura, Yukihiko*; Sahara, Masae*; Suzuki, Junichi*; Miura, Daisuke*; Torikai, Naoya*

J-PARC 20-02; J-PARC MLF Annual Report 2019, p.38 - 40, 2021/00

https://j-parc.jp/researcher/MatLife/ja/publication/files/MLF-AR_2019.pdf

Journal Articles

Elucidation of the morphology of the hydrocarbon multi-block copolymer electrolyte membranes for proton exchange fuel cells

Zhao, Y.; Yoshida, Miru*; Oshima, Tatsuya*; Koizumi, Satoshi*; Rikukawa, Masahiro*; Szekely, N.*; Radulescu, A.*; Richter, D.*

Polymer, 86, p.157 - 167, 2016/03

https://doi.org/10.1016/j.polymer.2016.01.061

Times Cited Count：13 Percentile：40.28(Polymer Science)

Journal Articles

A Crafty utilization of intermediate-angle neutron scattering and contrast variation by water-exchange to study the microstructure of microbial cellulose

Zhao, Y.; Koizumi, Satoshi*; Kondo, Tetsuo*

JPS Conference Proceedings (Internet), 8, p.033002_1 - 033002_6, 2015/09

https://doi.org/10.7566/JPSCP.8.033002

Journal Articles

Measurements and evaluations of air dose rates around Fukushima, 3; Characteristics of environmental rays and the exposure doses

Saito, Kimiaki; Endo, Akira

Radioisotopes, 63(12), p.585 - 602, 2014/12

https://doi.org/10.3769/radioisotopes.63.585

The article provides the fundamental information necessary for the appropriate evaluation of exposure doses in the environment. The basic characteristics of environmental rays from typical environmental sources are introduced; then, the dose conversion coeffcients for the public at different ages are summarized which were obtained from the simulation considering the basic characteristics of environmental rays. Further, the variations of environmental exposure doses due to a variety of factors, and the relation of exposure doses to measured air dose rates are discussed.

Journal Articles

Seasonal characteristics of chemical compositions of the atmospheric aerosols collected in urban seaside area at Tokaimura, eastern central Japan

Fu, F.; Watanabe, Kazuo; Yabuki, Sadayo*; Akagi, Tasuku*

Journal of Geophysical Research, 109(20), p.D20212_1 - D20212_9, 2004/10

Size-separated aerosol samples were collected at Tokaimura urban seaside area of Japan using an Andersen type sampler during July 2002 to July 2003. The size-separated aerosols were divided into water-soluble and insoluble fractions, and chemical compositions (Na $^{+}$ , Cl $^{-}$ , NH $_{3}$ $^{+}$ , NO $_{3}$ $^{-}$ , SO $_{4}$ $^{2-}$ , Al, Ca, Mg, Fe, Pb, Th and U) in both water-soluble and insoluble fractions were analyzed. Then, the seasonal variations and the size-distribution in mass concentration and chemical composition have been investigated in detail. Our results showed that the atmospheric aerosol in Tokaimura was obviously affected by dust storm in China, and that sea-salt particles were bigger than those in the Antarctic and were deficient in chlorine.

Journal Articles

Global potential energy surfaces for the lowest three doublet states (1 $^{2}$ A', 2 $^{2}$ A', and 1 $^{2}$ A") of the BrH $_{2}$ system

Kurosaki, Yuzuru; Takayanagi, Toshiyuki

Journal of Chemical Physics, 119(15), p.7838 - 7856, 2003/10

https://doi.org/10.1063/1.1609398

Times Cited Count：26 Percentile：62.76(Chemistry, Physical)

Adiabatic potential energy surfaces of the lowest three doublet states (1 $^{2}$ A', 2 $^{2}$ A', and 1 $^{2}$ A") for the BrH $_{2}$ system have been calculated globally using the MRCI+Q method with the aug-cc-pVTZ basis set. Spin-orbit effects were considered on the basis of Breit-Pauli Hamiltonian. The calculated adiabatic energies were fitted to the analytical functional form of many-body expansion. The barrier heights of the abstraction and exchange reactions on the ground-state PES were calculated to be 1.28 and 11.71 kcal mol $^{-1}$ , respectively, at the MRCI+Q/aug-cc-pVTZ level of theory. The fits for the three PESs were successful within the accuracy of 0.1 kcal mol $^{-1}$ . Thermal rate constants for the abstraction and exchange reactions and their isotopic variants were calculated with the fitted 1 $^{2}$ A' PES using the ICVT/LAG method. The calculated rate constants for the abstarction reactions agree fairly well with experiment but those for the exchange reactions were much smaller than experiment, which suggests that the reliable experimental data are still insufficient.

Journal Articles

Anthropogenic radionuclides in seawater of the Japan Sea; The Results of recent expeditions carried out in the Japanese and Russian EEZ

Ito, Toshimichi; Aramaki, Takafumi*; Otosaka, Shigeyoshi; Suzuki, Takashi; Togawa, Orihiko; Kobayashi, Takuya; Senju, Tomoharu*; Chaykovskaya, E. L.*; Lishavskaya, T. S.*; Karasev, E. V.*; et al.

Proceedings of International Symposium on Radioecology and Environmental Dosimetry, p.396 - 401, 2003/10

no abstracts in English

Journal Articles

Atmospheric deposition of $^{7}$ Be, $^{40}$ K, $^{137}$ Cs and $^{210}$ Pb during 1993-2001 at Tokai-mura, Japan

Ueno, Takashi; Nagao, Seiya; Yamazawa, Hiromi

Journal of Radioanalytical and Nuclear Chemistry, 255(2), p.335 - 339, 2003/02

https://doi.org/10.1023/A:1022508921409

Times Cited Count：21 Percentile：77.44(Chemistry, Analytical)

To evaluate the migration of radionuclides to the ground surface, deposition was collected from 1993 to 2001 with basin set up at Japan Atomic Energy Research Institute at Tokai-mura. Monthly basin samples were evaporated to dryness to obtain residual samples.These samples were measured by a well type Ge detector for natural and fallout radionuclide. These monthly depositions showed a clear seasonal variation with peaks in the early spring from February to April, and also in May in some years. The depositions of $^{40}$ K and $^{137}$ Cs have good correlation with the dry weight of deposited material, the depositions of $^{7}$ Be and $^{210}$ Pb showed much lower correlation coefficients. This difference in the correlation coefficient between these two groups of radionuclides can be attributed to the difference in the originating processes. These features in the concentration are thought to be caused by the difference in mechanism and location of origination, which would result in difference in the contributing particle size, and hence by the difference in the transport and deposition processes.

JAEA Reports

Characteristics of radiophotoluminescent glass dosimeters, FY2000

Ito, Masashi; Shiraishi, Akemi; Murakami, Hiroyuki

JAERI-Tech 2001-048, 20 Pages, 2001/07

JAERI-Tech-2001-048.pdf:1.27MB

In Japan Atomic Energy Research Institute, a new type radiophotoluminescent(RPL) glass dosimeter is recently adopted replaced film badge for external personal monitoring. Some fundamental characteristics of this dosimeter, such as dose dependence linearity, energy dependence, dose evaluation accuracy against mixed irradiation condition,fading, etc.,were examined at the Facility of Radiation Standard(FRS),JAERI. The results have proved that the RPL glass dosimeter has sufficient characteristics in practical use as a personal dosimeter for all of the items examined.

Journal Articles