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Kita K, Igarashi Y, Kinase T, Hayashi N, Ishizuka M, Adachi K, Koitabashi M, Sekiyama TT, Onda Y. Rain-induced bioecological resuspension of radiocaesium in a polluted forest in Japan. Sci Rep 2020; 10:15330. [PMID: 32948784 PMCID: PMC7501248 DOI: 10.1038/s41598-020-72029-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Accepted: 08/07/2020] [Indexed: 12/03/2022] Open
Abstract
It is the conventional understanding that rain removes aerosols from the atmosphere. However, the question of whether rain plays a role in releasing aerosols to the atmosphere has recently been posed by several researchers. In the present study, we show additional evidence for rain-induced aerosol emissions in a forest environment: the occurrence of radiocaesium-bearing aerosols in a Japanese forest due to rain. We carried out general radioactive aerosol observations in a typical mountainous village area within the exclusion zone in Fukushima Prefecture to determine the impacts and major drivers of the resuspension of radiocaesium originating from the nuclear accident in March 2011. We also conducted sampling according to the weather (with and without rain conditions) in a forest to clarify the sources of atmospheric radiocaesium in the polluted forest. We found that rain induces an increase in radiocaesium in the air in forests. With further investigations, we confirmed that the fungal spore sources of resuspended radiocaesium seemed to differ between rainy weather and nonrainy weather. Larger fungal particles (possibly macroconidia) are emitted during rainy conditions than during nonrainy weather, suggesting that splash generation by rain droplets is the major mechanism of the suspension of radiocaesium-bearing mould-like fungi. The present findings indicate that radiocaesium could be used as a tracer in such research fields as forest ecology, meteorology, climatology, public health and agriculture, in which fungal spores have significance.
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Affiliation(s)
- Kazuyuki Kita
- Graduate School of Science and Engineering, Ibaraki University, 2-1-1 Bunkyo, Mito, Ibaraki, 310-8512, Japan.
| | - Yasuhito Igarashi
- Graduate School of Science and Engineering, Ibaraki University, 2-1-1 Bunkyo, Mito, Ibaraki, 310-8512, Japan.
- Institute for Integrated Radiation and Nuclear Science, Kyoto University, 2 Asashiro-Nishi, Kumatori, Sennan, Osaka, 590-0494, Japan.
- Institute for Integrated Radiation and Nuclear Science, Kyoto University and College of Science, Ibaraki University, Formerly at Center for Research in Isotopes and Environmental Dynamics, University of Tsukuba, Tsukuba, Japan.
| | - Takeshi Kinase
- Meteorological Research Institute, 1-1 Nagamine, Tsukuba, Ibaraki, 305-0052, Japan
- Meteorological Research Institute and Formerly at College of Science, Ibaraki University, Ibaraki, Japan
| | - Naho Hayashi
- Graduate School of Science and Engineering, Ibaraki University, 2-1-1 Bunkyo, Mito, Ibaraki, 310-8512, Japan
| | - Masahide Ishizuka
- Faculty of Engineering and Design, Kagawa University, 2217-20 Hayashi-cho, Takamatsu, Kagawa, 761-0396, Japan
| | - Kouji Adachi
- Meteorological Research Institute, 1-1 Nagamine, Tsukuba, Ibaraki, 305-0052, Japan
| | - Motoo Koitabashi
- Forage Crop Protection Group, Division of Livestock Feeding and Management, Central Region Agricultural Research Center, National Agriculture and Food Research Organization, 768 Senbonmatsu, Nasushiobara, Tochigi, 329-2793, Japan
| | | | - Yuichi Onda
- Center for Research in Isotopes and Environmental Dynamics, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8577, Japan
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Igarashi Y, Kita K, Maki T, Kinase T, Hayashi N, Hosaka K, Adachi K, Kajino M, Ishizuka M, Sekiyama TT, Zaizen Y, Takenaka C, Ninomiya K, Okochi H, Sorimachi A. Fungal spore involvement in the resuspension of radiocaesium in summer. Sci Rep 2019; 9:1954. [PMID: 30760819 PMCID: PMC6374464 DOI: 10.1038/s41598-018-37698-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2018] [Accepted: 12/10/2018] [Indexed: 01/17/2023] Open
Abstract
We observed the atmospheric resuspension of radiocaesium, derived from the Fukushima Dai-ichi Nuclear Power Plant accident, at Namie, a heavily contaminated area of Fukushima, since 2012. During the survey periods from 2012 to 2015, the activity concentrations of radiocaesium in air ranged from approximately 10-5 to 10-2 Bq per m3 and were higher in the warm season than in the cold season. Electron microscopy showed that the particles collected on filters in summer were predominantly of biological origin (bioaerosols), with which the observed radiocaesium activity concentration varied. We conducted an additional aerosol analysis based on fluorescent optical microscopic observation and high-throughput DNA sequencing technique to identify bioaerosols at Namie in 2015 summer. The concentrations of bioaerosols fluctuated the order of 106 particles per m3, and the phyla Basidiomycota and Ascomycota (true Fungi) accounted for approximately two-thirds of the bioaerosols. Moreover, the fungal spore concentration in air was positively correlated with the radiocaesium concentration at Namie in summer 2016. The bioaerosol emissions from Japanese mixed forests in the temperate zone predominately included fungal cells, which are known to accumulate radiocaesium, and should be considered an important scientific issue that must be addressed.
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Affiliation(s)
- Yasuhito Igarashi
- Meteorological Research Institute, 1-1 Nagamine, Tsukuba, Ibaraki, 305-0052, Japan.
- Graduate School of Science and Engineering, Ibaraki University, 2-1-1 Bunkyo, Mito, Ibaraki, 310-8512, Japan.
- Center for Research in Isotopes and Environmental Dynamics, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8577, Japan.
- Center for Research in Isotopes and Environmental Dynamics, University of Tsukuba and Graduate School of Science and Engineering, Ibaraki University, and formerly at Meteorological Research Institute, Ibaraki, Japan.
| | - Kazuyuki Kita
- Graduate School of Science and Engineering, Ibaraki University, 2-1-1 Bunkyo, Mito, Ibaraki, 310-8512, Japan.
| | - Teruya Maki
- Institute of Science and Engineering, Kanazawa University, Kakumamachi, Kanazawa, Ishikawa, 920-1192, Japan
| | - Takeshi Kinase
- Meteorological Research Institute, 1-1 Nagamine, Tsukuba, Ibaraki, 305-0052, Japan
- Graduate School of Science and Engineering, Ibaraki University, 2-1-1 Bunkyo, Mito, Ibaraki, 310-8512, Japan
- Meteorological Research Institute and formerly at College of Science, Ibaraki University, Ibaraki, Japan
| | - Naho Hayashi
- Graduate School of Science and Engineering, Ibaraki University, 2-1-1 Bunkyo, Mito, Ibaraki, 310-8512, Japan
| | - Kentaro Hosaka
- Department of Botany, National Museum of Nature and Science, 4-1-1 Amakubo, Tsukuba, Ibaraki, 305-0005, Japan
| | - Kouji Adachi
- Meteorological Research Institute, 1-1 Nagamine, Tsukuba, Ibaraki, 305-0052, Japan
| | - Mizuo Kajino
- Meteorological Research Institute, 1-1 Nagamine, Tsukuba, Ibaraki, 305-0052, Japan
| | - Masahide Ishizuka
- Faculty of Engineering and Design, Kagawa University, 2217-20 Hayashi-cho, Takamatsu, Kagawa, 761-0396, Japan
| | | | - Yuji Zaizen
- Meteorological Research Institute, 1-1 Nagamine, Tsukuba, Ibaraki, 305-0052, Japan
| | - Chisato Takenaka
- Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Nagoya, 464-8601, Japan
| | - Kazuhiko Ninomiya
- Graduate School of Science, Osaka University, 1-1, Machikaneyama, Toyonaka, Osaka, 560-0043, Japan
| | - Hiroshi Okochi
- Research Institute for Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo, 169-8555, Japan
| | - Atsuyuki Sorimachi
- Fukushima Medical University, 1 Hikariga-oka, Fukushima, 960-1295, Japan
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Ishizuka M, Mikami M, Tanaka TY, Igarashi Y, Kita K, Yamada Y, Yoshida N, Toyoda S, Satou Y, Kinase T, Ninomiya K, Shinohara A. Use of a size-resolved 1-D resuspension scheme to evaluate resuspended radioactive material associated with mineral dust particles from the ground surface. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2017; 166:436-448. [PMID: 26872744 DOI: 10.1016/j.jenvrad.2015.12.023] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/24/2015] [Accepted: 12/27/2015] [Indexed: 06/05/2023]
Abstract
A size-resolved, one-dimensional resuspension scheme for soil particles from the ground surface is proposed to evaluate the concentration of radioactivity in the atmosphere due to the secondary emission of radioactive material. The particle size distributions of radioactive particles at a sampling point were measured and compared with the results evaluated by the scheme using four different soil textures: sand, loamy sand, sandy loam, and silty loam. For sandy loam and silty loam, the results were in good agreement with the size-resolved atmospheric radioactivity concentrations observed at a school ground in Tsushima District, Namie Town, Fukushima, which was heavily contaminated after the Fukushima Dai-ichi Nuclear Power Plant accident in March 2011. Though various assumptions were incorporated into both the scheme and evaluation conditions, this study shows that the proposed scheme can be applied to evaluate secondary emissions caused by aeolian resuspension of radioactive materials associated with mineral dust particles from the ground surface. The results underscore the importance of taking soil texture into account when evaluating the concentrations of resuspended, size-resolved atmospheric radioactivity.
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Affiliation(s)
- Masahide Ishizuka
- Kagawa University, 2217-20 Hayashi-cho, Takamatsu, Kagawa, 761-0396, Japan.
| | - Masao Mikami
- Japan Meteorological Business Support Center, 3-17 Kanda-Nishikicho, Chiyoda-ku, Tokyo, 101-0054, Japan.
| | - Taichu Y Tanaka
- Atmospheric Environment Division, Japan Meteorological Agency, 1-3-4 Otemachi, Chiyoda-ku, Tokyo, 100-8122, Japan.
| | - Yasuhito Igarashi
- Meteorological Research Institute, Japan Meteorological Agency, 1-1 Nagamine, Tsukuba, Ibaraki, 305-0052, Japan.
| | - Kazuyuki Kita
- Ibaraki University, 2-1-1 Bunkyo, Mito, Ibaraki, 310-8512, Japan.
| | - Yutaka Yamada
- RIKEN, 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan.
| | - Naohiro Yoshida
- Tokyo Institute of Technology, G1-17, 4259 Nagatsuta, Midori-ku, Yokohama, 226-8502, Japan.
| | - Sakae Toyoda
- Tokyo Institute of Technology, G1-17, 4259 Nagatsuta, Midori-ku, Yokohama, 226-8502, Japan.
| | - Yukihiko Satou
- University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8577, Japan.
| | - Takeshi Kinase
- Ibaraki University, 2-1-1 Bunkyo, Mito, Ibaraki, 310-8512, Japan.
| | - Kazuhiko Ninomiya
- Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka, 560-0043, Japan.
| | - Atsushi Shinohara
- Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka, 560-0043, Japan.
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Meisenberg O, Tschiersch J. Test of methods for retrospective activity size distribution determination from filter samples. RADIAT MEAS 2015. [DOI: 10.1016/j.radmeas.2015.03.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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