摘要
为系统研究石羊河流域中下游浅层地下水水化学特征及主要离子来源,于2018年6-8月采集地下水水化学样品62组。综合运用数理统计、Gibbs图、离子比例关系和水文地球化学模拟等方法,分析了石羊河流域中下游浅层地下水的水文地球化学特征,探讨了水化学演化过程及主要离子来源。结果表明:研究区浅层地下水在水平方向上呈现明显的水化学分带,从中游至下游地下水水化学类型由SO4·HCO3-Na·Ca型过渡为SO4·Cl-Na·Mg型,TDS含量也随之升高,流域中游为TDS含量小于1g/L的淡水,至下游演化为TDS含量高于1g/L的微咸水和咸水。该区浅层地下水水化学组分主要受水岩作用和蒸发浓缩作用控制,Ca^(2+)、Mg^(2+)主要来源于硅酸盐岩和碳酸盐岩的溶解,碳酸盐岩以白云石风化溶解为主,部分水样点存在方解石的风化溶解,阳离子交换作用是影响研究区地下水化学组分的重要过程。模拟结果表明沿地下水流向,地下水离子组分浓度呈递增趋势,岩盐、白云石和石膏发生溶解,方解石沉淀;从中游到下游地下水中阳离子交换作用越来越强烈,且阳离子交换作用强于溶解沉淀作用。
In order to systematically study the chemical characteristics and main ion sources of shallow groundwater in the midstream and downstream areas of Shiyang river basin,62 groundwater samples were collected and tested in June to August,2018.Based on the methods of mathematical statistics,Gibbs diagram,ion ratios,and hydrogeochemical simulation,the hydrogeochemical characteristics of the shallow groundwater were analyzed,and the hydrochemical evolution process and the main ion sources were discussed.The results show that the hydrochemical types of the shallow groundwater in study area present horizontal zonation in the direction of groundwater runoff,the hydrochemical type of groundwater transfers from SO4·HCO3-Na·Ca in midstream to SO4·Cl-Na·Mg in downsteam,and the TDS content also increases.The fresh water in midstream of the study area with a TDS content of less than 1 g/L evolve into brackish water and saline water with a TDS content of more than 1 g/L in downstream.The chemical composition of shallow groundwater in this area is mainly controlled by water-rock interaction and evaporation.Ca^(2+)and Mg^(2+)are mainly controlled by the dissolution of silicate rock and carbonate rock.The dissolution of carbonate rock is mainly dolomite,and the weathering dissolution of calcite exists in some water samples.Cation exchange is an important process that affects the chemical composition of groundwater in this area.Simulation results show that along the direction of groundwater,the concentrations of groundwater ions components are increasing,rock salt,dolomite and gypsum are dissolved,and calcite is precipitated.From midsteam to downstream areas the cation exchange effect is stronger and stronger,and the cation exchange effect is stronger than the dissolved precipitation effect.
作者
蒙琪
MENG Qi(Institute of Hydrogeology and Engineering Geology of Gansu Bureau of Geology and Mineral Exploration and Development,Zhangye 734000,China)
出处
《干旱区资源与环境》
CSSCI
CSCD
北大核心
2021年第3期80-87,共8页
Journal of Arid Land Resources and Environment
关键词
水化学特征
水化学作用
反向水文地球化学模拟
饱和指数
石羊河流域
characteristics of hydrochemistry
hydrochemical type
reverse hydrogeochemical simulation
saturation index
Shiyang River Basin
