Post-deposition early-phase migration and retention behavior of radiocesium in a litter-mineral soil system in a Japanese deciduous forest affected by the Fukushima nuclear accident
Post-deposition early-phase migration and retention behavior of radiocesium in a litter-mineral soil system in a Japanese deciduous forest affected by the Fukushima nuclear accident
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DOI：
10.1016/j.chemosphere.2016.09.043
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发表时间：
2016-12-01
期刊：
影响因子：
8.8
通讯作者：
Muto, Kotomi
中科院分区：
文献类型：
--
作者：
Koarashi, Jun;Nishimura, Syusaku;Muto, Kotomi
(T)he福岛核事故放射性铯（Cs-137）的归宿及其辐射风险在很大程度上取决于其在日本森林生态系统枯落物系统中的迁移和滞留行为。然而，这种行为还没有得到很好的量化。在日本福岛核事故后不久的落叶阔叶林中建立了野外蒸渗仪，连续监测了Cs-137在3个深度的向下转移：凋落物矿物土壤边界和矿物土壤中5 cm和10 cm深度。2011年5月至2015年5月在森林内的两个地点进行了观察。结果显示，类似的时间和深度的变化Cs-137向下通量的两个网站。Cs-137向下通量在各深度均呈逐年下降趋势，表明Cs-137从林下凋落物层中快速淋溶，然后通过与粘土矿物的相互作用固定在上层（0-5 cm）矿质土壤层中。Cs-137通量也表现出季节性变化，这与穿透雨和土壤温度的变化在网站。在事故发生后的第三和第四年，在10厘米深的矿物土壤中没有可检测到的Cs-137通量。在沉积后的早期阶段观察到的移动的（或生物可利用的）Cs-137的库存减少表明，在日本落叶林的凋落物土壤系统提供的只是一个临时的来源Cs-137在植物中的回收。(C)2016爱思唯尔有限公司版权所有。
(T)he fate of radiocesium (Cs-137) derived from the Fukushima nuclear accident and associated radiation risks are largely dependent on its migration and retention behavior in the litter soil system of Japanese forest ecosystems. However, this behavior has not been well quantified. We established field lysimeters in a Japanese deciduous broad-leaved forest soon after the Fukushima nuclear accident to continuously monitor the downward transfer of Cs-137 at three depths: the litter mineral soil boundary and depths of 5 cm and 10 cm in the mineral soil. Observations were conducted at two sites within the forest from May 2011 to May 2015. Results revealed similar temporal and depth-wise variations in Cs-137 downward fluxes for both sites. The Cs-137 downward fluxes generally decreased year by year at all depths, indicating that Cs-137 was rapidly leached from the forest-floor litter layer and was then immobilized in the upper (0-5 cm) mineral soil layer through its interaction with clay minerals. The Cs-137 fluxes also showed seasonal variation, which was in accordance with variations in the throughfall and soil temperature at the sites. There was no detectable Cs-137 flux at a depth of 10 cm in the mineral soil in the third and fourth years after the accident. The decreased inventory of mobile (or bioavailable) Cs-137 observed during early stages after deposition indicates that the litter soil system in the Japanese deciduous forest provides only a temporary source for Cs-137 recycling in plants. (C) 2016 Elsevier Ltd. All rights reserved.