基于室内土柱试验的多组分溶质迁移规律研究

Experimental Study of Multi-Component Solute Transport in a Saturated Soil Column

摘要: 库底沉积物在控制库水中污染物运移的归趋及其有效性中起着关键作用，为揭示多组分溶质在非饱和带中的迁移规律和机理，采用室内土柱试验，研究三泉水库库水与库底沉积物之间多组分溶质的作用过程。根据各个离子的迁移规律可以得出：1) 对该地区地下水可能造成威胁的指标包括：COD、Fe²⁺、Mn²⁺及F⁻。2) 不同土层COD迁移转化规律大体一致，波动上升后其含量稳定在初始浓度的1.5倍；由于土柱中氧化还原环境向还原环境发展，十分有利于铁锰由岩土向水中迁移，库水经过淤积层后，Fe²⁺含量以1.3倍初始值、Mn²⁺含量以2倍初始值向下迁移；F⁻是相对污染较严重的离子，受到上层高氟水与本层溶出氟的叠加效应，使得土柱最下层F⁻含量高达初始溶液的16倍。3) 根据硝态氮和氨态氮迁移规律得出，氮元素对该地区地下水威胁不大。

Abstract: The sediment in the bottom of the reservoir plays a key role in controlling the migration of pollu-tants in the reservoir water and its effectiveness. In order to reveal its process and mechanism, the interaction process of multi component solute between the three spring pool water and the bottom sediments is discussed by the laboratory soil column test. As the migration rules of each ion can be seen: 1) The ions that may threaten the groundwater in this area include COD, Fe²⁺, Mn²⁺ and F⁻. 2) The migration and transformation law of COD in different soil layers is generally consistent, and its content fluctuates up to 1.5 times C0. Because the redox environment in the soil column develops to the reduction environment, it is very beneficial to the migration of iron and manganese from rock to water. After the reservoir water passes through the silt layer, the content of Fe²⁺ is 1.3 times of the initial value, and the content of Mn²⁺ is moved downward with the initial value of 2 times; F⁻ is a rel-atively polluted ion, and is highly fluorine in the upper layer. The superposition effect of water and the dissolved fluorine in this layer made the content of F⁻ in the bottom layer of soil column as high as 16 times that of the initial solution. 3) According to the migration rule of nitrate nitrogen and ammonia nitrogen, nitrogen has little threat to groundwater in this area.