Kurihara Momo, Onda Yuichi, Suzuki Hiroyuki, Iwasaki Yuichi, Yasutaka Tetsuo
National Institute of Advanced Industrial Science and Technology, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8567, Japan.
Center for Research in Isotopes and Environmental Dynamics, University of Tsukuba, 305-8577, Japan.
J Environ Radioact. 2018 Dec;192:1-9. doi: 10.1016/j.jenvrad.2018.05.012. Epub 2018 May 26.
We examined spatial variation in vertical Cs flux from the litter layer using lysimeters combined with copper-substituted Prussian blue in two forests (deciduous broad-leaved and Japanese cedar (Cryptomeria japonica)), approximately 40 km northwest of the Fukushima Daiichi Nuclear power plant. The study ran from August 2016 to February 2017 in three periods; summer (10 Aug-4 Oct), autumn (5 Oct-30 Nov) and winter (1 Dec-27 Feb). Twenty-five and 15 lysimeters were installed in the deciduous broad-leaved and the Japanese cedar sites within 400 and 300 m areas with 3-5 m intervals, respectively. The geometric means of the flux in the deciduous broad-leaved site were 0.51, 0.085 and 0.060 kBq/m/month in summer, autumn and winter periods, respectively. In the Japanese cedar site, the mean fluxes were 0.45, 0.036 and 0.023 kBq/m/month. The ratio of Cs flux during the survey period to litter Cs inventory was 6% and 1% on average in the deciduous broad-leaved and Japanese cedar sites, respectively. The Cs flux in the summer period was much larger than those in other periods, resulting from higher precipitation in the summer. Our fine scale observation with 5 m interval showed very large spatial variation in the Cs flux and the differences between maximum and minimum range from 8 to 104 times, but were mostly 20-25 times. The spatial variations in the Cs flux were affected positively by those in the litter Cs inventory and negatively by canopy openness.
我们在福岛第一核电站西北约40公里处的两片森林（落叶阔叶林和日本柳杉林）中，使用装有铜取代普鲁士蓝的渗漏计，研究了凋落物层垂直铯通量的空间变化。该研究于2016年8月至2017年2月分三个阶段进行；夏季（8月10日至10月4日）、秋季（10月5日至11月30日）和冬季（12月1日至2月27日）。在落叶阔叶林和日本柳杉林样地内，分别在400米和300米的区域内，以3至5米的间隔安装了25个和15个渗漏计。落叶阔叶林样地通量的几何平均值在夏季、秋季和冬季分别为0.51、0.085和0.060 kBq/m/月。在日本柳杉林样地，平均通量分别为0.45、0.036和0.023 kBq/m/月。在落叶阔叶林和日本柳杉林样地，调查期间铯通量与凋落物铯存量的平均比值分别为6%和1%。夏季的铯通量远高于其他时期，这是由于夏季降水量较高。我们以5米间隔进行的精细尺度观测显示，铯通量存在非常大的空间变化，最大值与最小值之间的差异为8至104倍，但大多为20至25倍。铯通量的空间变化受到凋落物铯存量的正向影响，而受到冠层开阔度的负向影响。
