Geochemical and grain-size distribution of radioactive and stable cesium in Fukushima soils: implications for their long-term behavior
Geochemical and grain-size distribution of radioactive and stable cesium in Fukushima soils: implications for their long-term behavior
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DOI：
10.1016/j.jenvrad.2014.07.025
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发表时间：
2014-12-01
影响因子：
2.3
通讯作者：
Tanaka, Satoru
中科院分区：
文献类型：
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作者：
Saito, Takumi;Makino, Hisashi;Tanaka, Satoru
土壤中放射性铯Cs-137的可获得性和流动性对于从福岛第一核电站事故中恢复至关重要。本研究调查了事故后在福岛县东部地区采集的11个土壤样品中Cs-137的地球化学和粒度分布。连续提取进行评估的Cs-137具有不同的地球化学作用与土壤组分的分布。该结果进一步与事故前土壤中存在的稳定铯Cs-133的结果进行了比较。还测定了Cs-137在不同粒度组分中的分布。放射性铯主要存在于强酸溶解提取物和提取残渣中，在粉砂和粘土颗粒中含量较高。X射线衍射分析表明，云母矿物以及高岭土矿物主要溶解的强酸处理。不同粒级土壤矿物中云母矿物含量与~（137）Cs含量的相关性表明，云母矿物是~（137）Cs在土壤中固定的主要矿物。强酸溶解提取物中Cs-137和Cs-133的同位素比值比水、离子交换和还原溶解提取物中的比值小3倍以上。这表明，事故发生后2年内，由于土壤粘土矿物对Cs-137的固定相对缓慢，Cs-137的分布没有达到稳定状态。(C)2014爱思唯尔有限公司版权所有。
Availability and mobility of radioactive cesium,Cs-137, in soils are crucial for recovery from the accident in the Fukushima Dai-ichi Nuclear Power Plants. In this study we investigated the geochemical and grain-size distribution of Cs-137 in 11 soil samples collected in the eastern area of Fukushima Prefecture after the accident. Sequential extractions were performed to evaluate the distribution of Cs-137 having different geochemical interactions with soil components. The result was further compared with that of the stable cesium, Cs-133, which had occurred in the soils before the accident. The distribution of Cs-137 in different grain-size fractions was also determined. Radioactive cesium was predominantly found in the extract obtained by strong-acid dissolution and the extraction residue and was more concentrated in silt and clay grains. X-ray diffraction analyses revealed that micaceous minerals as well as kaolin minerals were predominantly dissolved by the strong-acid treatment. Correlation between the fraction of Cs-137 and the content of micaceous minerals in different grain-size fractions of soil minerals suggests that micaceous minerals are responsible for the fixation of Cs-137 in the soils. The isotopic ratio of Cs-137 and Cs-133 in the extract by strong-acid dissolution was more than three times smaller than those in the extracts by water, ion exchange, and reductive dissolution. This indicates that the distribution of Cs-137 was not in the steady state in 2 y after the accident due to relatively slow fixation by the soil clay minerals. (C) 2014 Elsevier Ltd. All rights reserved.