A stepwise change of frayed edge site content in biotite in response to the gradual release of potassium from the interlayers
A stepwise change of frayed edge site content in biotite in response to the gradual release of potassium from the interlayers
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黑云母中磨损边缘位点含量的逐步变化响应钾从夹层的逐渐释放
DOI：
10.1080/00380768.2017.1402660
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发表时间：
2017
影响因子：
2
通讯作者：
Junta Yanai
中科院分区：
文献类型：
--
作者：
Sho Ogasawara;Atsushi Nakao;Junta Yanai
放射性铯（RCs）选择性地吸附在土壤中风化云母矿物（云母）上。虽然很明显，风化云母有选择性的吸附位点的RC，这被称为“磨损边缘网站（FES），”云母风化程度和FES含量之间的关系还没有得到充分的研究。为了评价云母风化对其FES含量的影响，采用四苯硼钠溶液研究了黑云母样品中FES含量随K+释放的变化。根据放射性铯拦截潜力估算了FES含量。蛭石层电荷（Vt电荷）也被确定为云母风化程度的指标。从黑云母中提取的K的量从154 mmol kg− 1增加到803 mmol kg− 1，因为K提取的条件更强烈（即，更长的时间、更低的固/液比和更高的温度）。随着K+被更大程度地去除，FES含量从3.96 mmol kg− 1增加到11.5 mmol kg−1，而Vt电荷值从17.1 mmol kg − 1增加到329 mmol kg−1。在云母风化的早期阶段，FES的形成与K+释放量的增加和Vt电荷成正比。然而，在云母风化的后期阶段，当蛭石被检测到的X-射线衍射分析，FES不一定增加成比例的K+释放和Vt电荷量的增加。这些结果表明，虽然云母风化大大增加了FES，增加不是连续的整个风化阶段，但在风化的早期阶段明显。
Radiocesium (RCs) is selectively adsorbed on weathered micaceous minerals (mica) in soils. Although it is clear that weathered mica has selective adsorption sites for RCs, which have been called ‘frayed edge sites (FES),’ the relationship between the degree of mica weathering and the FES content has not been fully investigated. To evaluate the effect of mica weathering on its FES content, we investigated the changes in the FES content with the release of K+from biotite samples by using sodium tetraphenylborate solution. The FES content was estimated from radiocesium interception potential. The vermiculitic layer charge (Vt charge) was also determined as an indicator of the degree of mica weathering. The amount of K extracted from biotite increased from 154 to 803 mmol kg−1as the condition of the K extraction was more intensive (i.e., longer time, lower solid/liquid ratio, and higher temperature). As K+was removed to a greater extent, the FES content increased from 3.96 to 11.5 mmol kg−1, whereas the Vt charge value increased from 17.1 to 329 mmol kg−1. At the earlier stage of mica weathering, the formation of FES was proportional to the increasing amount of K+released and to the Vt charges. However, at the later stage of mica weathering, when vermiculite was detected by an X-ray diffraction analysis, FES was not necessarily increased in proportion to the increase in K+released and the amount of Vt charge. These findings indicated that although mica weathering largely increased the FES, the increase was not continuous throughout the weathering stage but evident at the earlier stage of weathering.