Episode Analysis of Deposition of Radiocesium from the Fukushima Daiichi Nuclear Power Plant Accident

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• 作者：Yu Morino ; Toshimasa Ohara ; Mirai Watanabe ; Seiji Hayashi ; Masato Nishizawa
• 刊名：Environmental Science & Technology (ES&T)
• 出版年：2013
• 出版时间：March 5, 2013
• 年：2013
• 卷：47
• 期：5
• 页码：2314-2322
• 全文大小：833K
• 年卷期：v.47,no.5(March 5, 2013)
• ISSN：1520-5851

文摘

Chemical transport models played key roles in understanding the atmospheric behaviors and deposition patterns of radioactive materials emitted from the Fukushima Daiichi nuclear power plant after the nuclear accident that accompanied the great Tohoku earthquake and tsunami on 11 March 2011. However, model results could not be sufficiently evaluated because of limited observational data. We assess the model performance to simulate the deposition patterns of radiocesium (¹³⁷Cs) by making use of airborne monitoring survey data for the first time. We conducted ten sensitivity simulations to evaluate the atmospheric model uncertainties associated with key model settings including emission data and wet deposition modules. We found that simulation using emissions estimated with a regional-scale (500 km) model better reproduced the observed ¹³⁷Cs deposition pattern in eastern Japan than simulation using emissions estimated with local-scale (50 km) or global-scale models. In addition, simulation using a process-based wet deposition module reproduced the observations well, whereas simulation using scavenging coefficients showed large uncertainties associated with empirical parameters. The best-available simulation reproduced the observed ¹³⁷Cs deposition rates in high-deposition areas (鈮?0 kBq m^鈥?) within 1 order of magnitude and showed that deposition of radiocesium over land occurred predominantly during 15鈥?6, 20鈥?3, and 30鈥?1 March 2011.