Presentation Interception of Te-132, I-131 and radiocesium deposition by wild herbaceous plants

Tagami, Keiko  ,  Uchida, Shigeo  ,  Ishii, Nobuyoshi

Radioactive materials from the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident had deposited in large areas in Eastern Japan. To estimate radiation dose to public under such emergency situation, it is important to supply environmental transfer parameter values to mathematical dose estimation models. One of the parameters is interception fraction of deposited radionuclides by plants to understand potential retention of radionuclides in plants. The interception fraction is defined as the ratio of the activity initially retained by the standing vegetation immediately subsequent to the deposition event (Bq/m2 in plant) to the total activity deposited (Bq/m2 in soil + plant). In this study, therefore we measured radionuclide concentrations in wild herbaceous plants collected in the National Institute of Radiological Sciences (NIRS) campus ca. 220 km south from the FDNPP. In the same area, we also collected fallout deposition samples from 15 March 2011 until 22 April 2011 so that area fallout deposition data were available. During the sampling period, we found one large deposition event which were due to rain fall on 21-22 March 2011; this rain event contaminated large areas of Kanto region where about 30% of Japanese live.On 28 March 2011, at NIRS campus, we collected six wild herbaceous plants, e.g., mugwort (Artemisia indica var. maximowiczii), giant butterbur (Petasites japonicus (Siebold et Zucc.) Maxim.) dandelion (Taraxacum), Japanese dock (Rumex japonicas), field horsetail (Equisetum arvense L.), and wild onion (Allium macrostemon). There was no heavy rain between 22 and 28 March 2011. These plants were chopped into small pieces and all the pieces were transferred into a plastic container for gamma-ray measurement with Ge-detecting systems (Seiko EG&G Ortec) for 2000-5000 s. Radioactivity concentrations were decay corrected to 28 March 2011.
13th International Conference on the Biogeochemistry of Trace Elements (ICOBTE 2015)

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