黏性土对地下水中盐分运移和同位素组成的影响

The Influence of Clay on the Salt Movement and Isotope Composition in Groundwater

在土壤介质中,地下水及盐分如何运移一直是影响地下水资源计算评价的一个重要问题。黏性土层与含水层具有不同的岩性组成,对地下水和盐分的运移起着不同的作用,导致盐分和水在黏性土的运移规律并不相同。本研究选择华北平原黏性土作为研究对象,利用100 m深度上黏性土中地下水连续的水化学和同位素数据,分析了黏性土对含水层间的水力联系及盐分运移的影响。试验表明,黏性土水中电导率的变化主要与补给来源的电导率有关,在垂向剖面上具有比较连续的变化趋势,反映出地下水垂向补给的特征;同时,电导率在一定深度上存在数值的突变,反映了黏性土的阻盐特性,说明黏性土具有一定半透膜作用。由于黏性土的隔水和半透膜特性,稳定同位素在不同深度上的组成受到黏性土分布的影响,其分布规律对地下水资源评价具有参考价值。

The movement of salt and groundwater in soil is an important constitution in evaluation of groundwater resources.Because clay and aquifer have different structures, and play different roles in migration of groundwater and salt, the migration patterns of salt and groundwater in clay are different. In this study, groundwater water samples were taken from clay in depth（100 m）, and all samples were tested for stable isotopes, including hydrogen and oxygen isotope, and hydrogeochemical indexes. This research analyzed the hydraulic connection of groundwater in different aquifer and salt movement in clay by using isotopic and chemical data. The result shows that the electrical conductivity is influenced by origination of groundwater,having a continuous trend with depth, and clay in certain depth presented the feature of impeding salt migration. Because of the semipermeable feature of clay, stable isotope distribution of groundwater in different depth is affected by clay ＇s distribution. This regular pattern of isotope and hydrogeochemical distribution would be a reference for evaluation of groundwater resources.