Nguyen Phuong Thoa, Kaneko Shingo, Koya Shishido, Ohira Hajime, Tsukada Hirofumi
Graduate School of Symbiotic Systems Science and Technology, Fukushima University, 1 Kanayagawa, Fukushima City, Fukushima Prefecture 960-1296, Japan; Institute of Environmental Radioactivity, Fukushima University, 1 Kanayagawa, Fukushima City, Fukushima Prefecture 960-1296, Japan.
Faculty of Symbiotic Systems Science, Fukushima University, 1 Kanayagawa, Fukushima City, Fukushima Prefecture 960-1296, Japan; Institute of Environmental Radioactivity, Fukushima University, 1 Kanayagawa, Fukushima City, Fukushima Prefecture 960-1296, Japan.
Sci Total Environ. 2021 Jul 20;779:146350. doi: 10.1016/j.scitotenv.2021.146350. Epub 2021 Mar 11.
After the 2011 Fukushima Dai-ichi Nuclear Power Station (FDNPS) accident, wild populations of animals and plants living in the evacuation zone received additional ionizing radiation of both internal and external radiation doses. Morphological abnormalities of pine and fir trees near the FDNPS were reported. In order to evaluate dose-effect relationships, it is necessary to quantify the radiation doses to trees and plants. In this study, the internal and external dose rates to Japanese cedar and plants collected at three sites in Okuma, approximately 4 km southwest of FDNPS were estimated applying the ERICA Assessment Tool. The activity concentrations of Cs and Cs in soils, cedar trunks, and plants were determined. The total dose rates to cedar ranged from 2.2 ± 1.2 to 6.1 ± 2.2 μGy h. These rates were within the derived consideration reference levels (DCRLs) reported by ICRP 108 as 4-40 μGy h for pine trees. The highest estimate for plants was 7.1 ± 2.7 μGy h, much smaller than the DCRLs reported for grasses and herbs (40-400 μGy h). On average, the internal radiation dose rates to cedars at the two sites accounted for 5% and 29% of the external dose rates, respectively, while the value in another site was only 0.4% for cedar. This was attributed to differences in the crown area between the three sites. The trunk diameter of cedars shows a positive correlation with the ratio of internal to external radiation dose rates. It indicates that the total dose rate to cedars is easily estimated with the soil radiocaesium inventory and trunk diameter. The internal radiation dose rate to the plant varied depending on the plant species. This variation was considerably large in plants due to the presence of two species, including Solidago altissima and Artemisia indica var. maximowiczii.
2011年福岛第一核电站事故后，生活在撤离区的动植物野生种群受到了额外的内、外照射剂量的电离辐射。有报道称福岛第一核电站附近的松树和冷杉出现了形态异常。为了评估剂量效应关系，有必要对树木和植物所接受的辐射剂量进行量化。在本研究中，应用ERICA评估工具估算了在距福岛第一核电站西南约4公里的大熊町三个地点采集的日本雪松和植物的内、外剂量率。测定了土壤、雪松树干和植物中铯-134和铯-137的活度浓度。雪松的总剂量率范围为2.2±1.2至6.1±2.2微戈瑞/小时。这些剂量率在国际放射防护委员会（ICRP）第108号报告中给出的松树的导出考虑参考水平（DCRLs）4-40微戈瑞/小时范围内。植物的最高估算剂量率为7.1±2.7微戈瑞/小时，远低于报告的草本植物的DCRLs（40-400微戈瑞/小时）。平均而言，两个地点雪松的内照射剂量率分别占外照射剂量率的5%和29%，而另一个地点雪松的这一数值仅为0.4%。这归因于三个地点树冠面积的差异。雪松的树干直径与内、外辐射剂量率之比呈正相关。这表明利用土壤放射性铯存量和树干直径可以很容易地估算出雪松的总剂量率。植物的内照射剂量率因植物种类而异。由于包括一枝黄花和大岛蒿在内的两种植物的存在，植物中的这种差异相当大。
