宜昌长江南岸岩溶地下水系统水化学特征分析

Hydrochemical Characteristics of Karst Groundwater System on the South Bank of the Yangtze River in Yichang

湖北宜昌长江南岸地区属典型的南北岩溶交界区岩溶地貌,岩溶地下水为当地主要供水水源,研究不同岩溶含水层中地下水的水化学特征将有助于当地地下水的合理开发利用与保护,并可为岩溶含水层的划分提供依据。基于湖北宜昌长江南岸岩溶地下水水化学组成与岩石化学组成特征,运用相关分析和因子分析等数理统计方法探讨了该地区岩溶地下水水化学组分特征及其影响因素。结果表明:研究区赋存于不同岩溶含水岩组中的地下水水化学组成不同,主要的岩溶地下水水化学类型为HCO_(3)-Ca型、HCO_(3)-Ca·Mg型和HCO_(3)·SO_(4)-Ca·Mg型,各岩溶含水层中岩石矿物组成与地下水水化学离子组成具有良好的对应关系,方解石、白云石和石膏矿物为主要发生溶滤作用的矿物,矿物类型及其占比极大地影响了研究区水文地球化学过程;影响研究区岩溶地下水水化学特征的主要影响因素为地层岩性、水动力条件和人类活动,其中地层岩性是最主要的控制因素,是研究区岩溶地下水中绝大部分离子的物质来源。

The area on the south bank of the Yangtze River in Yichang, Hubei, is a typical karst landform in the north-south karst junction area, where karst groundwater is the main source of water supply.Studying the hydrochemical characteristics of different karst aquifers will be helpful to the rational development, utilization and protection of local groundwater, and provide a basis for the division of karst aquifers.Based on the chemical composition of groundwater and rock, the chemical composition characteristics of groundwater and its influencing factors on the south bank of the Yangtze River in Yichang are discussed using mathematical statistical methods such as correlation analysis and factor analysis.The results show that the hydrochemical composition of groundwater in different karst water-bearing rock groups is different.The main karst hydrochemical types are HCO_(3)-Ca type, HCO_(3)-Ca·Mg type, and HCO_(3)·SO_(4)-Ca·Mg type, with each containing water.The rock mineral composition of different aquifers has a good correspondence with the chemical ion composition of the groundwater.Calcite, dolomite and gypsum minerals are the main ones that undergo leaching.The type and proportion of minerals greatly affect the hydrogeochemical process.It is concluded that the main factors affecting karst groundwater chemistry in the study area are stratum lithology, hydrodynamic conditions and human activities.Stratum lithology is the most important controlling factor, and it is the material source of most of the ions in groundwater.