Vertical distributions of radiocesium in Japanese forest soils following the Fukushima Daiichi Nuclear Power Plant accident: A meta-analysis
Vertical distributions of radiocesium in Japanese forest soils following the Fukushima Daiichi Nuclear Power Plant accident: A meta-analysis
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DOI：
10.1016/j.jenvrad.2020.106422
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发表时间：
2020-12-01
影响因子：
2.3
通讯作者：
Shaw, George
中科院分区：
文献类型：
--
作者：
Imamura, Naohiro;Komatsu, Masabumi;Shaw, George
本研究利用三个简单参数，研究了福岛第一核电站（FDNPP）事故发生初期（2011年至2017年）日本森林土壤中放射性元素库存垂直分布的时间变化。我们利用99个土壤清查数据集计算了有机层的分数（F-l/t）、迁移中心（X-c）和松弛深度（alpha）。从2011年到2017年，F-l/t显著下降（logistic分析，p < 0.001）。此外，从第一年到第二年，FDNPP区F-l/t与切尔诺贝利核电站区相比迅速下降。由于有机凋落物特征、气候和初始沉积的物理化学形式等因素的影响，本研究与以往ChNPP研究的有机土壤向矿物土壤迁移速率存在差异。广义混合模型分析显示，在FDNPP区矿质土层中，只有X-c随时间显著增加（p < 0.01）。然而，ChNPP区的X-c和α在1986年事故发生后的2 ~ 5年内有所下降，表明即使在事故发生后的第5年，有机层中的Cs-137保留率仍然很高。FDNPP区矿质土层中Cs-137的垂直迁移可能是由于第2年后从有机到表层矿质土层的Cs-137输入量减少所致。这些结果表明，有机层的Cs-137截留能力会影响下伏矿质土层中Cs-137的表观垂直迁移。
This study investigated the temporal change in vertical distributions of radiocesium inventories in Japanese forest soils during the early phase (from 2011 to 2017) following the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident, using three simple parameters. We calculated the fraction in the organic layer (F-l/t), the migration center (X-c) and the relaxation depth (alpha) using 99 soil inventory data sets. F-l/t decreased significantly from 2011 to 2017 (logistic analysis, p < 0.001). In addition, F-l/t in the FDNPP zone rapidly decreased compared to that in the Chernobyl Nuclear Power Plant (ChNPP) zone from the first year to the second year. Different migration rates from organic to mineral soil layers between previous studies in the ChNPP and this study have several possible causes such as organic litter features, climate and physico-chemical forms of initial deposition. In mineral soil layers in the FDNPP zone, only X-c increased significantly with time according to generalized mixed model analysis (p < 0.01). However, X-c and alpha in the ChNPP zone decreased from two to five years after the accident in 1986, which shows a high Cs-137 retention in the organic layer even in the fifth year after the accident. The vertical migration of Cs-137 in the mineral soil layer in the FDNPP zone appears to be due to low input of Cs-137 from organic to surface mineral soil layer after the second year. These results indicate that Cs-137 retention capacity of the organic layer can affect the apparent vertical migration of Cs-137 in the underlying mineral soil layer.