Low Level Radioactivity Laboratory, Institute of Nature and Environmental Technology, Kanazawa University, Wake O24, Nomi, Ishikawa 923-1224, Japan.
Graduate School of Natural Science and Technology, Kanazawa University, Kakuma, Kanazawa, Ishikawa 920-1192, Japan.
Radiat Prot Dosimetry. 2022 Sep 9;198(13-15):947-956. doi: 10.1093/rpd/ncac018.
In order to determine the long-term impacts of radiocesium contamination on ecosystems in watersheds and coastal areas following the Fukushima Daiichi Nuclear Power Plant accident in March 2011, it was important to monitor the transport behavior of radiocesium from an early stage. In this study, conducted from July 2011 to October 2020, we carried out field research along the Natsui and Same rivers running through watersheds in the south of Fukushima Prefecture, Japan, in which there had been a relatively low accumulation of radiocesium. We found that under normal flow conditions, the total (dissolved + particulate phase) activity of 137Cs decreased with increasing time following the accident. However, the water samples collected after rain events showed higher activity of up to 895 mBq l-1 with a higher percentage (>92% of total) of the particulate phase. These findings indicate that radiocesium deposited on the ground surface is predominantly transported in the particulate phase from watersheds to rivers via precipitation. The decontamination process, which was performed in the farmland during December 2014 to March 2015 and in forest during February 2013 to April 2014, was small effects of the transport of 137Cs. Under normal flow conditions, total 137Cs activity was largely determined by the suspended solids (SS) concentration and/or 137Cs concentration in the SS.
为了确定 2011 年 3 月福岛第一核电站事故后流域和沿海地区放射性铯污染对生态系统的长期影响，从早期监测放射性铯的迁移行为非常重要。在这项从 2011 年 7 月至 2020 年 10 月进行的研究中，我们沿着流经日本福岛县南部流域的 Natsui 和 Same 河进行了实地研究，这些地区放射性铯的积累相对较少。我们发现，在正常流量条件下，事故发生后，总（溶解+颗粒相）137Cs 活性随时间的增加而降低。然而，雨后采集的水样显示出更高的活性，高达 895mBq l-1，其中颗粒相的比例更高（>总活性的 92%）。这些发现表明，沉积在地表的放射性铯主要通过降水以颗粒相从流域输送到河流。2014 年 12 月至 2015 年 3 月在农田进行的去污过程以及 2013 年 2 月至 2014 年 4 月在森林进行的去污过程对 137Cs 的迁移影响很小。在正常流量条件下，总 137Cs 活性主要由悬浮固体（SS）浓度和/或 SS 中的 137Cs 浓度决定。
