量研学術機関リポジトリ「QST-Repository」は、国立研究開発法人 量子科学技術研究開発機構に所属する職員等が生み出した学術成果(学会誌発表論文、学会発表、研究開発報告書、特許等)を集積しインターネット上で広く公開するサービスです。 Welcome to QST-Repository where we accumulates and discloses the academic research results(Journal Publications, Conference presentation, Research and Development Report, Patent, etc.) of the members of National Institutes for Quantum and Radiological Science and Technology.
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The Fukushima Daiichi Nuclear Power Plant (FDNPP) accident has caused serious radioactive contamination in the environment. Among the released radionuclides, the behaviour of Cs-137 has been concerned because this radionuclide has a 30-years half-life and a significant amount of Cs-137(1.5x1016 Bq) was released into the atmosphere. Accordingly, sludge generated in the drinking water plants was also contaminated with the Cs-137 in a certain areas. Before the accident, the sludge was effectively reused as materials for construction, playground soils, and potting mixes. Various vegetables are planted in potting mixes in home gardens, and thus the contaminated sludge would be a source of Cs-137 in vegetables. Intake of the Cs-137-contaminated vegetables causes internal radiation exposure.
The standard limit for radiocesium in general foods (100 Bq/kg) has been applied to agricultural crops from April 1, 2012 to ensure safety. However measurement of Cs-137 in the vegetables harvested in home gardens has not been carried out before their consumption in many cases. To ensure safety and security, it is important to understand the transfer of Cs-137 from the sludge to vegetables.
We recently demonstrated the root uptake of Cs-137 from the potting mix containing the contaminated sludge by Brassica rapa var. perviridis (Japanese name: komatsuna) (Ishii et al. 2013a) and Brassica oleracea spp. (Japanese name: mini cabbage) (Ishii et al. 2013b). In those experiments, various particle sizes of the sludge were used although particle size is likely to affect soil-to-plant transfer factor (IAEA 2006). Here, we show the effect of sludge particle size on the uptake of Cs-137 by a leaf vegetable, komatsuna.