| 西南表层岩溶带土壤中砷的迁移规律实验与模拟 |
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| 引用本文： | 曾斌,韦晓青,邹胜章,李录娟,黄荷.西南表层岩溶带土壤中砷的迁移规律实验与模拟[J].地球科学,2018,43(11):4237-4245. |
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| 作者姓名： | 曾斌 韦晓青 邹胜章 李录娟 黄荷 |
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| 作者单位： | 1.中国地质大学环境学院, 湖北武汉 430074 |
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| 基金项目： | 中国地质科学院岩溶地质研究所基本科研业务费项目2015016 |
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| 摘 要： | 岩溶地下河是我国西南地区的重要水源，工业生产过程中产生的砷污染物，除通过落水洞等直接进入并污染地下水外，还会在表层岩溶带溶缝、溶隙内吸附、滞留及富集，并在特定条件下再次迁移，成为"稳定次生污染源".以广西某砷污染事件为例，采用窄缝槽物理模型装置进行砷的动态吸附、解吸实验，并结合地球化学模拟研究砷污染物在表层岩溶带土壤中的迁移规律.实验结果显示表层岩溶带对砷的吸附以物理吸附（扩散过程）为主，相比吸附过程而言解吸速率则显得缓慢，而酸溶液相比去离子水可促进砷的解吸过程.地球化学模拟结果表明土壤矿物中以针铁矿对砷的吸附贡献最大，而酸溶液通过溶蚀针铁矿等矿物削弱对砷的吸附能力.因此在西南岩溶地区，表层岩溶带系统一旦纳入砷污染物，则解吸过程缓慢，易形成砷污染物的滞留、富集；而酸雨作用下砷的解吸、迁移过程加快，则会提高地下水系统的污染风险.
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| 关 键 词： | 表层岩溶带 砷污染 物理模型实验 地球化学模拟 水文地质 |
| 收稿时间： | 2018-08-04 |
Experiment and Simulation on Migration Rule of Arsenic in Soil of Surface Karst Zone in Southwest China |
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| Abstract: | Karst underground river is an important water source in Southwest China. In addition to entering and polluting the groundwater directly through the sinkholes, arsenic pollutants produced from the industrial production process will also adsorb, remain, and concentrate in the dissolution cracks and gaps in the surface karst zone, and remigrate under certain conditions to become a "secondary pollution source". Taking an arsenic pollution event in Guangxi as an example, the dynamic adsorption and desorption experiments of arsenic were carried out by using narrow slot physical model device, and the migration rule of arsenic contamination in the soil of surface karst zone was studied, combined with geochemical simulation. The experimental results show that the adsorption of arsenic in the surface karst zone is mainly physical adsorption (diffusion process), and the desorption rate is slow compared with the adsorption process, while the acid solution can promote the desorption process of arsenic compared with deionized water. The results of geochemical simulation show that goethite contributes most to arsenic adsorption in soil minerals, while acid solution weakens the ability of arsenic adsorption by corroding goethite and other minerals. It is concluded that in the karst area of Southwest China, once the surface karst zone system is integrated with arsenic pollutants, the desorption process is slow, and it is easy to form the retention and enrichment of arsenic pollutants; while the accelerated desorption and migration process of arsenic under acid rain will increase the pollution risk of groundwater system. |
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