Shifts of radiocesium vertical profiles in sediments and their modelling in Japanese lakes
Shifts of radiocesium vertical profiles in sediments and their modelling in Japanese lakes
复制标题
DOI：
10.1016/j.scitotenv.2017.09.286
复制
发表时间：
2018-02-15
影响因子：
9.8
通讯作者：
Onda, Yuichi
中科院分区：
文献类型：
--
作者：
Fukushima, Takehiko;Komatsu, Eiji;Onda, Yuichi
为了研究沉积-扩散过程，在2011年福岛核事故后不同时间采集的5个不同形态和营养特征的日本湖泊(Hinuma、Kasumigaura、Kitaura、Onogawa和Sohara)的沉积物岩心中，测量了放射性铯浓度的垂直分布。在沉积物具有高孔隙度和由于浅层而经历相当大的波浪作用的湖泊中，我们观察到放射性铯在事故发生后立即迅速渗透到一定深度，随后峰值深度向下移动。相比之下，在其他类型的湖泊中发现了不同峰值的逐渐向下转移。建立了一个具有水-沉积物相互作用过程的一维微分沉积物模型来描述放射性铯剖面的垂直移动。我们提出的与利用风应力和沉积物孔隙度进行混合的长度尺度相关的子模型是基于对三个湖泊(Hinuma、Kasumigaura和Sohara)中放射性铯垂直分布的一次测量而建立的。然后使用不同年份的这些湖泊以及另外两个湖泊的样本对该模型进行了验证。取得了较好的一致性。我们讨论了我们的发现，模型应用的局限性，以及未来的研究目标。(C)2017爱思唯尔B.V.保留所有权利。
Vertical profiles of radiocesium concentrations were measured in sediment cores collected at various times after the 2011 Fukushima nuclear accident in five Japanese lakes (Hinuma, Kasumigaura, Kitaura, Onogawa and Sohara) with different morphological and trophic characteristics in order to investigate the sedimentation-diffusion processes. In lakes where sediments had high porosities and experienced considerable wave action due to shallowness, we observed rapid penetration of radiocesium to a certain depth just after the accident, followed by downward movement of the peak depths. In contrast, gradual downward transfers of distinct peaks were found in other types of lakes. A one-dimensional differential sediment model with water-sediments interaction processes was constructed to describe the vertical shift of radiocesium profiles. Our proposed submodels relating to the length scales of the mixing using wind-induced stress and porosity of sediments were constructed based on one measurement of the vertical distribution of radiocesium in three lakes (Hinuma, Kasumigaura and Sohara). This model was then validated using samples from those lakes in different years, as well as from two other lakes. Good agreement was obtained. We discuss our findings, the limits of model application, and future research targets. (C) 2017 Elsevier B.V. All rights reserved.