Since Fukushima accident, dozens of field studies have been conducted in order to quantify and understand the behaviour of atmospheric radiocesium (¹³⁷Cs) fallouts in contaminated forests of Fukushima and neighbouring prefectures. In this paper, we carry out a detailed review of data acquired over 2011–2017 in Japanese cedar and cypress plantations, focusing on aerial tree organs, soil layers and tree-to-soil depuration fluxes. To enable comparison and reinforce the consistency between sites, radiological measurements were normalized by the deposit and interpolated onto the same spatio-temporal frame. Despite some (poorly explained) residual variability, we derived a “mean” pattern by log-averaging data among sites. These “mean” results were analysed with the help of a simple mass-balance approach and discussed in the light of post-Fukushima literature. We demonstrated that the activity levels and dynamics in all compartments were consistent and generally well reproduced by the mass balance approach, for values of the interception fraction between 0.7 and 0.85. The analysis indicated that about 5% of the initial deposit remained in the aerial vegetation after 6 years, more than two thirds of intercepted ¹³⁷Cs being transferred to the soil due to throughfall. The simulations indicated that foliar uptake might have contributed between 40% and 100% to the activity transferred to stem wood. The activity concentration in canopy organs rapidly decreased in the first few months then more slowly, according to an effective half-life of about 1.6 years. The activity level in the organic layer peaked in summer 2011 then decreased according to an effective half-life of 2.2 years. After a rapid increase in 2011, the contamination of mineral horizons continued to increase more slowly, 85% of ¹³⁷Cs incoming through the organic layer being retained in the 0–5 cm layer according to a mean residence time longer than in the upper layer (7 against 1.5 years).

自福岛事故以来，已经进行了数十次现场研究，以量化和了解大气中放射性铯的行为（¹³⁷Cs）在福岛及邻近县的受污染森林中的污染。在本文中，我们对2011-2017年日本雪松和柏树人工林中获得的数据进行了详细回顾，重点研究了空中树木器官，土壤层和树木至土壤的净化通量。为了能够进行比较并增强站点之间的一致性，对放射学测量结果进行了归一化处理，并将其插值到相同的时空框架上。尽管存在一些（很少有解释的）剩余变异性，但我们通过对站点之间的数据进行对数平均得出了“均值”模式。这些“平均”结果借助简单的质量平衡方法进行了分析，并根据福岛后的文献进行了讨论。我们证明了所有部分的活性水平和动力学是一致的，并且质量截留方法通常可以很好地再现这些活性，并且截留分数的值介于0.7和0.85之间。分析表明，6年后约有5％的初始沉积物保留在空中植被中，超过三分之二被截留¹³⁷ Cs由于穿透而被转移到土壤中。模拟表明，叶面吸收可能对转移至茎木的活性贡献了40％至100％。根据约1.6年的有效半衰期，在最初的几个月中，冠层器官中的活动浓度迅速下降，然后缓慢下降。有机层的活性水平在2011年夏季达到峰值，然后根据2.2年的有效半衰期降低。在2011年迅速增加之后，矿物层位的污染继续缓慢增加，通过有机层进入的¹³⁷ Cs的85％被保留在0-5 cm层中，这是由于平均停留时间长于上层（ 7年（1.5年）。