Tabelin Carlito Baltazar, Sasaki Ryosuke, Igarashi Toshifumi, Park Ilhwan, Tamoto Shuichi, Arima Takahiko, Ito Mayumi, Hiroyoshi Naoki
Division of Sustainable Resources Engineering, Faculty of Engineering, Hokkaido University, Japan.
Furukawa Co., Ltd., Osaka, Japan.
Chemosphere. 2017 Dec;188:444-454. doi: 10.1016/j.chemosphere.2017.08.088. Epub 2017 Aug 23.
Predicting the fates of arsenic (As) and selenium (Se) in natural geologic media like rocks and soils necessitates the understanding of how their various oxyanionic species behave and migrate under dynamic conditions. In this study, geochemical factors and processes crucial in the leaching and transport of arsenite (As), arsenate (As), selenite (Se) and selenate (Se) in tunnel-excavated rocks of marine origin were investigated using microscopic/extraction techniques, column experiments, dissolution-precipitation kinetics and one-dimensional reactive transport modeling. The results showed that evaporite salts were important because aside from containing As and Se, they played crucial roles in the evolution of pH and concentrations of coexisting ions, both of which had strong effects on adsorption-desorption reactions of As and Se species with iron oxyhydroxide minerals/phases. The observed leaching trends of As, As, Se and Se were satisfactorily simulated by one-dimensional reactive transport models, which predict that preferential adsorptions of As and Se were magnified by geochemical changes in the columns due to water flow. Moreover, our results showed that migrations of As, Se and Se could be predicted adequately by 1D solute transport with simple activity-K' approach, but surface complexation was more reliable to simulate adsorption-desorption behavior of As.
预测砷（As）和硒（Se）在岩石和土壤等天然地质介质中的归宿，需要了解它们的各种含氧阴离子物种在动态条件下的行为和迁移方式。在本研究中，利用微观/萃取技术、柱实验、溶解-沉淀动力学和一维反应性输运模型，研究了海洋成因的隧道开挖岩石中亚砷酸盐（As(III)）、砷酸盐（As(V)）、亚硒酸盐（Se(IV)）和硒酸盐（Se(VI)）淋滤和迁移过程中的关键地球化学因素和过程。结果表明，蒸发盐很重要，因为除了含有As和Se外，它们在pH值和共存离子浓度的演变中起着关键作用，这两者对As和Se物种与铁羟基氧化物矿物/相的吸附-解吸反应都有很强的影响。一维反应性输运模型令人满意地模拟了观察到的As(III)、As(V)、Se(IV)和Se(VI)的淋滤趋势，该模型预测，由于水流作用，柱中的地球化学变化会放大As和Se的优先吸附。此外，我们的结果表明，采用简单活度-K'方法的一维溶质输运能够充分预测As(III)、Se(IV)和Se(VI)的迁移，但表面络合对于模拟As(V)的吸附-解吸行为更为可靠。
