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Soil radon (Rn-222) monitoring in a forest site in Fukushima, Japan

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Please use this identifier to cite or link to this item:http://hdl.handle.net/2115/61443

Title: Soil radon (Rn-222) monitoring in a forest site in Fukushima, Japan
Authors: Fujiyoshi, Ryoko Browse this author →KAKEN DB
Ohno, Misato Browse this author
Okamoto, Kazumasa Browse this author →KAKEN DB
Umegaki, Kikuo Browse this author
Keywords: 222Rn
Soil air
Monitoring
Gas transportation
Typhoon
Fukushima
Issue Date: Apr-2015
Publisher: Springer
Journal Title: Environmental earth sciences
Volume: 73
Issue: 8
Start Page: 4135
End Page: 4142
Publisher DOI: 10.1007/s12665-014-3698-3
Abstract: Soil radon (Rn-222) has been monitored since August 2013 at three different soil depths on a campus forest of Fukushima University in Japan, where a large amount of fallout nuclides were released by the accident of Fukushima Daiichi Nuclear Power Plant in March 2011. The primary purpose of this study is to evaluate Rn-222 activity level, variability and factors controlling Rn-222 concentration in soil air using data obtained from August to December 2013. Time series of Rn-222 activity concentration showed depth-dependent variability with an equilibrium value (Rn-222(eq)) during this observation period; 7.5, 14 and 23 kBq m(-3) at 0.3, 0.6 and 1.0 m in depth, respectively. Two typhoons passing over the site had a great influence on soil radon level, which was practically used for evaluating effective diffusion coefficient of Rn-222. Transport mechanism of Rn-222 in soil air was considered to be diffusion-controlled with data sets on changing Rn-222 concentration with time in selected cases that showed decreasing (or increasing) Rn-222 concentration with time at every depth. Important factors affecting soil Rn-222 variability are meteorological parameters, low-pressure front passing over the site, and subsequent precipitation. Time lags of decreasing Rn-222 concentration at different depths after rain indicate a certain relationship of Rn-222 level with moving water (and water vapor) in soil. The findings obtained in this study are important to evaluate the fate of fallout nuclides (radiocesium) in contaminated forest sites using soil radon as a tracer of moving soil air.
Rights: The final publication is available at link.springer.com
Type: article (author version)
URI: http://hdl.handle.net/2115/61443
Appears in Collections:国際連携研究教育局 : GI-CoRE (Global Institution for Collaborative Research and Education : GI-CoRE) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)
工学院・工学研究院 (Graduate School of Engineering / Faculty of Engineering) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)

Submitter: 藤吉 亮子

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