不同土地利用方式对岩溶含水介质各向异性的影响研究--以重庆青木关岩溶槽谷区为例

On Influence of Different Land Use upon Karst Aquifer Medium Anisotropy——A case study on the typical karst valley of Qingmuguan in Chongqing

以重庆青木关岩溶农业槽谷为例,采用对比分析的方法研究地下岩溶含水系统各向异性,分析本区槽谷内南北两条相对独立的地下河管道各向异性结构对物质运移影响的差异.对比南北两段地下水化学变化特征,结果表明:受土地利用类型的影响,不同离子沿管道运移质量浓度变化各不相同:pH值、电导率及各离子质量浓度总体呈南段大于北段的趋势;地下河水中的δ15 N比值南段在-21.432‰～+37.825‰之间,北段在-5.573‰～+5.851‰之间,表明南段地下河受到水田化肥和粪便的污染,而北段地下河主要受土壤有机氮和化肥等人类农业活动综合影响;Ca2+在两段含水介质中运移从上游到下游增加;K+在各测点的质量浓度变化很大,水田附近的K+质量浓度较高,地下河出口质量浓度变化最大;SO24-和Cl-质量浓度在两段地下河中同升同降,PO34-,NO3-受人类活动影响显著.

With Qingmuguan Underground River in chongqing karst agricultural valley as an example, and by means of comparative analysis, karst underground water system anisotropic structure has been explored, and the differences of aquifer anisotropic structure between two underground river systems analyzed. With the comparison of the spatiotemporal variation characteristics of hydrochemistry with the Southern and Northern groundwater, the results show that each ion concentration is of inequality when migration along the pipe by the influence of land use types： The overall change trend in spatial variation is downstream〉upstream, southern〉northern; the ratio of 31SN is between -21. 432%0±37. 825%o along southern underground river, and -5. 573%0±5. 851%0 along northern underground river. It also shows that Southern is mainly affected by paddy field fertilizer and Animal manure, and Northern is soil organic nitrogen fertilizer. Cae＋ in aquifer medium has enrichment effect from the upriver to downriver. K＋ changes a lot at every point and is higher nearby paddy fields, so concentration changes at the underground river export is the biggest. SO2-4 and C1- concentration increases or decreases at the same time, PO4a- and NO3- significant reflect the influence of human activity.