Yoschenko Vasyl, Takase Tsugiko, Konoplev Alexei, Nanba Kenji, Onda Yuichi, Kivva Sergiy, Zheleznyak Mark, Sato Natsumi, Keitoku Koji
Institute of Environmental Radioactivity of Fukushima University, 1 Kanayagawa, Fukushima, Fukushima Prefecture, 960-1296, Japan.
Institute of Environmental Radioactivity of Fukushima University, 1 Kanayagawa, Fukushima, Fukushima Prefecture, 960-1296, Japan.
J Environ Radioact. 2017 Jan;166(Pt 1):45-55. doi: 10.1016/j.jenvrad.2016.02.017. Epub 2016 Mar 3.
The Fukushima-derived radiocesium distribution in the typical Japanese cedar (Cryptomeria japonica D. Don) forest ecosystem was determined. In four years after the Fukushima accident, about 74% of the total radiocesium inventory was localized in soil, 20% was in the litter, and only 6% was associated with the aboveground biomass. Most of the radiocesium that was initially intercepted by the tree canopies has been already transported to the ground surface. The importance of the processes for removal of radiocesium from the tree canopies decreased in the order litterfall > throughfall >> stemflow. Within the tree compartments, the largest radiocesium activity fraction, about 46%, was observed in old foliage, which indicates that the process of removal of the initial deposit from the tree crowns has not yet completed. The aggregate soil-to-wood transfer factor was 1.1⋅10 m kg d.w., which is close to the geometric means of transfer factors recommended by IAEA for other coniferous tree species. Further studies in Fukushima forest are necessary to assess the variation of this parameter under various soil-landscape conditions. Presence of the residues of the initial deposits does not allow to obtain the accurate values of the annual radiocesium fluxes in the ecosystem. Based on the conservative assumptions, the ranges of the fluxes were estimated. Analysis of the flux structures shows that up to percents of the total radiocesium activity in the ecosystem may be involved into biogenic cycling.
确定了源自福岛的放射性铯在典型日本柳杉（Cryptomeria japonica D. Don）森林生态系统中的分布。在福岛事故后的四年里，放射性铯总量的约74%集中在土壤中，20%在凋落物中，仅有6%与地上生物量相关。最初被树冠截留的大部分放射性铯已被输送到地面。从树冠去除放射性铯的过程的重要性按凋落物>穿透雨>>树干径流的顺序降低。在树木各部分中，老龄叶片中观察到的放射性铯活度分数最大，约为46%，这表明从树冠去除初始沉积物的过程尚未完成。土壤到木材的总转移系数为1.1⋅10 m kg d.w.，接近国际原子能机构为其他针叶树种推荐的转移系数的几何平均值。有必要在福岛森林进行进一步研究，以评估该参数在各种土壤景观条件下的变化。初始沉积物残留物的存在使得无法获得生态系统中年度放射性铯通量的准确值。基于保守假设，估计了通量范围。通量结构分析表明，生态系统中高达一定百分比的放射性铯总活度可能参与生物地球化学循环。
