Effects of additional layer(s) on the mobility of arsenic from hydrothermally altered rock in laboratory column experiments
Effects of additional layer(s) on the mobility of arsenic from hydrothermally altered rock in laboratory column experiments
复制标题
实验室柱实验中附加层对热液蚀变岩石中砷迁移率的影响
DOI：
10.1007/s11270-017-3295-7
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发表时间：
2017
期刊：
影响因子：
--
通讯作者：
T. Igarashi
中科院分区：
文献类型：
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作者：
P. Tangviroon;R. Hayashi;T. Igarashi
在日本北海道修建隧道时，经常会遇到热液蚀变岩。高浓度的有害元素，如砷（As），经常从这些岩石释放到周围环境中。因此，这些岩石被认为是潜在的危险废物。本文描述了水含量和氧气（O2）浓度对附加层的影响，即，利用实验室柱上的含水量和O2浓度传感器，研究了表面覆盖层和底部吸附层对As淋失的影响。结果表明，使用附加层对降低As迁移具有显著效果。这不仅与吸附层对As的吸附能力有关，还与岩石层内部的含水量和O2浓度有关。在有附加层的情况下，岩石层中孔隙水的积累增加，这导致岩石层中的O2浓度降低。因此，砷的浸出的含砷矿物在岩层中的氧化减少。此外，较长的水在岩层中的停留时间可能会导致铁的羟基氧化物/氧化物沉淀。这些结果表明，岩层的地球化学条件影响砷的淋溶和迁移。
Hydrothermally altered rocks are frequently encountered when tunnels are constructed in Hokkaido, Japan. High concentraions of hazardous elements, such as arsenic (As), are often released from these rocks into the surrounding environments. Therefore, the rocks are considered potentially hazardous waste. This article describes the effects of water content and oxygen (O2) concentration in relation to additional layer(s), i.e., surface covering and bottom adsorption layers, on As leaching by using laboratory columns with water content and O2concentration sensors. The results show that the use of additional layer(s) has a significant effect on lowering As migration. This was due not only to the adsorption capacity of As by the adsorption layer but also to the water content and O2concentration inside the rock layer. The accumulation of pore water was increased in the rock layer in cases with additional layer(s), which resulted in lower O2concentration in the rock layer. Consequently, the leaching of As by the oxidation of As-bearing minerals in the rock layer was reduced. Moreover, a longer water-resident time in the rock layer may induce precipitation of Fe oxy-hydroxide/oxide. These results suggest that the geochemical conditions of the rock layer affect As leaching and migration.