著者

Tadaaki BAN-NAI Yasuyuki MURAMATSU Satoshi YOSHIDA

出版者

Journal of Radiation Research Editorial Committee

雑誌

Journal of Radiation Research (ISSN:04493060)

巻号頁・発行日

vol.45, no.2, pp.325-332, 2004 (Released:2004-08-10)

参考文献数

58

被引用文献数

13

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Mushrooms are known to accumulate radiocesium. To estimate the intake of radiocesium through the eating of mushrooms, about 30 samples belonging to 4 commonly consumed species (Lentinula edodes, Hypsizigus marmoreus, Grifola frondosa, and Tricholoma matsutake), were analyzed for 137Cs and 40K. The concentration ranges were 0.060-29 Bq kg-1 (wet wt) for 137Cs and 38-300 Bq kg-1 (wet wt) for 40K. The geometric mean concentration for 137Cs was 0.56 Bq kg-1 (wet wt), and the mean concentration for 40K was 92 Bq kg-1 (wet wt). The 137Cs concentrations in L. edodes cultivated in mushroom beds (sawdust-rice bran media) were lower than those cultivated on bed logs (natural wood with bark). The annual intake of 137Cs per person through mushrooms was calculated, by using the current analytical results and food consumption data in Japan, to be 3.1 Bq for 137Cs, which is about 28% of the total dietary intake of this nuclide. The effective dose equivalent of 137Cs through mushrooms was estimated to be 4.0 ¤ 10-8 Sv, which is about the half the value obtained in our previous study. The decrease of the 137Cs intake through mushrooms is probably related to changes in cultivation methods in recent years, from the use of bed logs to mushroom beds.

著者

Shigeto Fujimura Kunio Yoshioka Takashi Saito Mutsuto Sato Makoto Sato Yuuki Sakuma Yasuyuki Muramatsu

出版者

日本作物学会

雑誌

Plant Production Science (ISSN:1343943X)

巻号頁・発行日

vol.16, no.2, pp.166-170, 2013 (Released:2013-03-19)

参考文献数

13

被引用文献数

45

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Radionuclides were released into the environment as a consequence of the Fukushima Daiichi Nuclear Power Plant accident that occurred on 11 March 2011. Radiocesium at an abnormal concentration was detected in brown rice produced in paddy fields located in northern part of Fukushima Prefecture. We examined several hypotheses that could potentially explain the excessive radiocesium level in brown rice in some of the paddy fields, including (i) low exchangeable potassium content of the soil, (ii) low sorption sites for cesium (Cs) in the soil, and (iii) radiocesium enrichment of water that is flowing into the paddy fields from surrounding forests. The results of experiments using pots with contaminated soil indicated that the concentration of radiocesium in rice plants was decreased by applying potassium or clay minerals such as zeolite and vermiculite. The obtained results indicated that high concentrations of radiocesium in rice are potentially a result of the low exchangeable potassium and sorption sites for Cs in the soils. Application of potassium fertilizer and clay minerals should provide an effective countermeasure for reducing radiocesium uptake by plants. Radiocesium-enriched water produced by leaching contaminated leaf litter was used to irrigate rice plants in the cultivation experiments. The results indicated that the radiocesium concentrations in rice plants increased when the radiocesium-enriched water was applied to the potted rice plants. This indicated the possibility that the radiocesium levels in brown rice will increase if the nuclide is transported with water into the rice paddy fields from surrounding forests.

著者

YASUTO MIYAKE HIROYUKI MATSUZAKI TAKESHI FUJIWARA TAKUMI SAITO TAKEYASU YAMAGATA MAKI HONDA YASUYUKI MURAMATSU

出版者

GEOCHEMICAL SOCIETY OF JAPAN

雑誌

GEOCHEMICAL JOURNAL (ISSN:00167002)

巻号頁・発行日

vol.46, no.4, pp.327-333, 2012-08-20 (Released:2013-11-08)

参考文献数

28

被引用文献数

1 92

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In March 2011, there was an accident at the Fukushima Daiichi Nuclear Power Plant (NPP) and a discharge of radionuclides resulting from a powerful earthquake. Considering the impact on human health, the radiation dosimetry is the most important for 131I among radionuclides in the initial stage immediately following the release of radionuclides. Since 131I cannot be detected after several months owing to its short half-life (8 days), the reconstruction by 129I (half-life: 1.57 × 107 yrs) analysis is important. For this reconstruction, it is necessary to know the isotopic ratio of 129I/131I of radioactive iodine released from the NPP. In this study, the 129I concentration was measured in several surface soil samples collected around the Fukushima Daiichi NPP for which the 131I level had already been determined. The surface deposition amount of 129I was between 15.6 and 6.06 × 103 mBq/m2 within the region 3.6 to 59.0 km distant from the NPP. 129I and 131I data had good linear correlation and the average isotopic ratio was estimated to be 129I/131I = 31.6 ± 8.9 as of March 15, 2011.