Reassessment of the radiocesium resuspension flux from contaminated ground surfaces in eastern Japan
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Published:2022-01-18
Issue:2
Volume:22
Page:783-803
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ISSN:1680-7324
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Container-title:Atmospheric Chemistry and Physics
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language:en
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Short-container-title:Atmos. Chem. Phys.
Author:
Kajino MizuoORCID, Watanabe Akira, Ishizuka MasahideORCID, Kita KazuyukiORCID, Zaizen Yuji, Kinase Takeshi, Hirai Rikuya, Konnai Kakeru, Saya Akane, Iwaoka Kazuki, Shiroma Yoshitaka, Hasegawa Hidenao, Akata Naofumi, Hosoda Masahiro, Tokonami Shinji, Igarashi YasuhitoORCID
Abstract
Abstract. Resuspension of 137Cs from the contaminated ground
surface to the atmosphere is essential for understanding the environmental
behaviors of 137Cs and estimating external and inhalation exposure of
residents. Kajino et al. (2016) assessed the 137Cs resuspension flux
from bare soil and forest ecosystems in eastern Japan in 2013 using a numerical
simulation constrained by surface air concentration measurements. However,
the simulation was found to underestimate the observed deposition amounts by
2 orders of magnitude. The reason for this underestimation is that the
simulation assumed that resuspended 137Cs is carried by submicron
aerosols, which have low deposition rates. Based on the observational
indications that soil dust and bioaerosols are the major carriers of
resuspended 137Cs, a new simulation is performed with higher deposition
rates constrained by both surface concentrations and deposition amounts. In
the new estimation, the total areal annual resuspension of 137Cs in
2013 is 25.7 TBq, which is equivalent to 0.96 % of the initial deposition
(2.68 PBq). Due to the rapid deposition rates, the annual redeposition
amount is also large at 10.6 TBq, approximately 40 % of the resuspended
137Cs. The resuspension rate through the atmosphere (0.96 % yr−1)
seems slow, but it (2.6 × 10−5 d−1) may not be negligibly
small compared to the actual decreasing trend of the ambient gamma dose rate
obtained in Fukushima Prefecture after the radioactive decay of 137Cs
plus 134Cs in 2013 is subtracted (1.0–7.9 × 10−4 d−1): resuspension can account for 1 %–10 % of the decreasing rate due
to decontamination and natural decay through land surface processes. The
current simulation underestimated the 137Cs deposition in Fukushima
city in winter by more than an order of magnitude, indicating the presence
of additional resuspension sources. The site of Fukushima city is surrounded
by major roads. Heavy traffic on wet and muddy roads after snow removal
operations could generate superlarge (approximately 100 µm in
diameter) road dust or road salt particles, which are not included in the
model but might contribute to the observed 137Cs at the site.
Funder
Japan Society for the Promotion of Science Nuclear Regulation Authority Environmental Restoration and Conservation Agency Ministry of Education, Culture, Sports, Science and Technology
Publisher
Copernicus GmbH
Subject
Atmospheric Science
Reference53 articles.
1. Adachi, K., Kajino, M., Zaizen, Y., and Igarashi, Y.: Emission of spherical
cesium-bearing particles from an early stage of the Fukushima nuclear
accident, Sci. Rep., 3, 12–15, https://doi.org/10.1038/srep02554, 2013. 2. Denby, B. R., Ketzel, M., Ellermann, T., Stojiljkovic, A., Kupiainen, K.,
Niemi, J. V., Norman, M., Johansson, C., Gustafsson, M., Blomqvist, G.,
Janhäll, S., and Sundvor, I.: Road salt emissions: A comparison of
measurements and modelling using the NORTRIP road dust emission model,
Atmos. Environ., 141, 508–522, https://doi.org/10.1016/j.atmosenv.2016.07.027, 2016. 3. Dépée, A., Lemaitre, P., Gelain, T., Mathieu, A., Monier, M., and
Flossmann, A.: Theoretical study of aerosol particle electroscavenging by
clouds, J. Aerosol Sci., 135, 1–20, https://doi.org/10.1016/j.jaerosci.2019.04.001,
2019. 4. Draxler, R., Arnold, D., Chino, M., Galmarini, S., Hort, M., Jones, A.,
Leadbetter, S., Malo, A., Maurer, C., Rolph, G., Saito, K., Servranckx, R.,
Shimbori, T., Solazzo, E., and Wotawa, G.: World Meteorological
Organization's model simulations of the radionuclide dispersion and
deposition from the Fukushima Daiichi nuclear power plant accident, J.
Environ. Radioact., 139, 172–184, https://doi.org/10.1016/j.jenvrad.2013.09.014, 2015. 5. Emanuel, K. A. and Živković-Rothman, M.: Development and evaluation
of a convection scheme for use in climate models, J. Atmos. Sci., 56,
1766–1782, https://doi.org/10.1175/1520-0469(1999)056< 1766:DAEOAC>2.0.CO;2, 1999.
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