Tanaka Kazuya, Iwatani Hokuto, Sakaguchi Aya, Fan Qiaohui, Takahashi Yoshio
Institute for Sustainable Sciences and Development, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8530, Japan.
Department of Earth and Planetary Systems Science, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan.
J Environ Radioact. 2015 Jan;139:390-397. doi: 10.1016/j.jenvrad.2014.05.002. Epub 2014 May 27.
We investigated the particle size distribution of radiocesium in riverbed sediments after the Fukushima Daiichi Nuclear Power Plant accident. Riverbed sediments were collected in the Abukuma River system in Fukushima and Miyagi Prefectures. The collected sediments were separated into 11 fractions, ranging from granular size (>2000 μm) to clay size (<2 μm) fractions. Cesium-137 concentrations were higher in the smaller particle size fractions, possibly reflecting specific surface areas and the mineralogy, in particular the clay mineral content. A gap in (137)Cs concentration was observed between the silt size and sand size fractions of riverbed sediments at downstream sites, whereas riverbed sediments at an upstream site did not show such a concentration gap. It is likely that selective transport of small particles in suspended state from upstream areas resulted in an accumulation of radiocesium in downstream areas.
我们调查了福岛第一核电站事故后河床沉积物中放射性铯的粒径分布。在福岛县和宫城县的阿武隈川水系采集了河床沉积物。将采集到的沉积物分成11个粒级，范围从颗粒大小（>2000μm）到黏土大小（<2μm）粒级。铯-137浓度在较小粒径粒级中较高，这可能反映了比表面积和矿物学特征，特别是黏土矿物含量。在下游站点的河床沉积物粉砂粒级和砂粒级之间观察到了（137）Cs浓度的差距，而上游站点的河床沉积物未显示出这种浓度差距。很可能是上游地区悬浮状态的小颗粒的选择性输运导致了下游地区放射性铯的积累。
