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Radioactivity Dynamics in forests

（2015）

ＱHow much radioactive cesium is released from forests? How much radioactive cesium flows into the sea?

ＡOf the initial deposit of 137Cs in forests after the accident, which is approximately 370TBq, it is estimated that approximately 1TBq was released into the sea in one year (examples of the Ukedo and Takase rivers).

Fig.1　Map for air dose rate (Nov.7,2014) around Ukedo River system7)

【Forest investigation】Flow from forests: Amount of cesium flowing out with soil is on average about 0.1% in a year. (Map project1),2), F-TRACE, NIES3))
【Analysis of soil flow】Outflow from other than forests: Estimated from SACT (Soil (Sediment) and Cesium (Contaminants) Transport model) (F-TRACE 4))
【Analysis of migration in river systems】Amount of radioactive cesium flowing out from Ogaki-dam at high water level is lower than 10% of that from forests. (Data by Ministry of Agriculture, Forestry and Fisheries5), F-TRACE6))
【River investigation】Measured data under the Map Project in 20131)

Reference： 1) Project entrusted by Nuclear Regulatory Agency, Report on the project “Establishment of the Methods for Long-term Effect of Radioactive Materials Released form Fukushima Daiichi Nuclear Power Station, TEPCO” (2013).. 2) Yoshimura, K. et al., J. Environ. Radioact., 139, pp.362-369(2015). 3) T. Nishikiori et al., J. Jpn. Forest Soc. 97, 63-69 (2015). 4) A. Kitamura et al., Anthropocene, 5, 22-31(2014). 5) Tohoku Regional Agricultural Administration Office, Ministry of Agriculture, Forestry and Fisheries “Results for Investigation of Radioactive Cesium in Ogaki-dam” (September 18, 2014). 6) H. Kurikami, et al., J. Environ. Radioact., 137, 10-17(2014). 7) Map Zoom-in Site for Radiation Distribution/ The Geospatial Information Authority of Japan

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Reference

  1. 日本原子力研究開発機構. “原子力規制庁委託事業「平成25年度東京電力（株）福島第一原子力発電所事故に伴う放射性物質の長期的影響把握手法の確立」事業 成果報告書”. 2014.
  2. Kurikami, H. at al., Sediment and 137Cs Behaviors in the Ogaki Dam Reservoir during a Heavy Rainfall Event, Journal of Environmental Radioactivity, vol.137, 2014, p.10-17.
  3. 錦織達啓ほか, 林床被覆の違いが土壌侵食に伴う放射性セシウムの移動に及ぼす影響, 日本森林学会誌, vol.97, no.1, 2015, p.63-69.
  4. Yoshimura, K. et al., Evaluation of Radiocaesium Wash-off by Soil Erosion from Various Land Uses using USLE Plots, Journal of Environmental Radioactivity, vol.139, 2015, p.362-369.