Small scale temporal distribution of radiocesium in undisturbed coniferous forest soil: Radiocesium depth distribution profiles
Small scale temporal distribution of radiocesium in undisturbed coniferous forest soil: Radiocesium depth distribution profiles
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原状针叶林土壤中放射性铯的小尺度时间分布：放射性铯深度分布剖面
DOI：
10.1016/j.jenvman.2016.01.014
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发表时间：
2016
影响因子：
8.7
通讯作者：
H.
中科院分区：
文献类型：
--
作者：
Mengistu T. Teramage;Onda;Y.;Kato;H.
在福岛核电站事故后 9 个月至 18 个月的四个采样日期，对未受干扰的针叶林土壤中福岛前和福岛衍生 137 Cs 的深度分布进行了调查。评估了采样曲线之间的迁移率和短期时间变异性。考虑福岛前 137Cs 峰值沉积以来经过的时间和峰值的中位深度，其向下位移速率范围为 0.15 至 0.67 mm yr−1，平均值为 0.46 ± 0.25 mm yr−1。另一方面，在每个检查剖面中，在有机层中都发现了相当数量的福岛衍生 137Cs (51%–92%)。此时，时间-距离对福岛137C向下分布的影响似乎看不见，因为其大部分仍然存在于有机质最多的层中。这表明有机物似乎是放射性铯的主要和优先吸附剂，可能与富含有机物的灰尘对交换位点的物理堵塞有关，这些灰尘充当放射性铯向下传播的缓冲器，这意味着放射性铯将在根区保留相当长的一段时间。因此，该土壤部分可能是潜在的辐射剂量源，很大程度上是由于放射性铯浓度高且密度低。一般来说，此类信息有助于建立动态的以安全为中心的决策支持系统，以简化和协助管理行动。
The depth distribution of pre-Fukushima and Fukushima-derived137Cs in undisturbed coniferous forest soil was investigated at four sampling dates from nine months to 18 months after the Fukushima nuclear power plant accident. The migration rate and short-term temporal variability among the sampling profiles were evaluated. Taking the time elapsed since the peak deposition of pre-Fukushima137Cs and the median depth of the peaks, its downward displacement rates ranged from 0.15 to 0.67 mm yr−1with a mean of 0.46 ± 0.25 mm yr−1. On the other hand, in each examined profile considerable amount of the Fukushima-derived137Cs was found in the organic layer (51%–92%). At this moment, the effect of time-distance on the downward distribution of Fukushima-derived137Cs seems invisible as its large portion is still found in layers where organic matter is maximal. This indicates that organic matter seems the primary and preferential sorbent of radiocesium that could be associated with the physical blockage of the exchanging sites by organic-rich dusts that act as a buffer against downward propagation of radiocesium, implying radiocesium to be remained in the root zone for considerable time period. As a result, this soil section can be a potential source of radiation dose largely due to high radiocesium concentration coupled with its low density. Generally, such kind of information will be useful to establish a dynamic safety-focused decision support system to ease and assist management actions.