基于同位素和水化学的北京平谷盆地地下水循环研究  

Study on Groundwater Cycle in Beijing Pinggu Basin Based on Isotopes and Hydrochemistry

作　　者：王新娟 许苗娟 韩旭 董佩 孙颖 WANG Xinjuan;XU Miaojuan;HAN Xu;DONG Pei;SUN Ying(Beijing Institute of Geological Environment Monitoring,Beijing 100195,China)

机构地区：[1]北京市地质环境监测所,北京100195

出　　处：《西北地质》2023年第5期127-139,共13页Northwestern Geology

基　　金：北京市科技计划课题“永定河流域(北京段)地下水涵养储备与保护修复研究及示范”(Z191100006919001)。

摘　　要：通过在区域开展地下水同位素、水化学取样分析,研究了平谷泃河和洳河冲洪积扇地下水循环演化特征。分析结果显示:本次所取水样pH值为7.6~8.1,为中性水;阳离子含量均以Ca^(2+)、Mg^(2+)为主,占70%以上,阴离子含量以HCO3−为主,占82%以上,所取水样地下水水化学类型均为HCO3•Ca•Mg型。研究区浅层第四系松散孔隙水δ^(2)H值和δ^(18)O值分别为64.9‰、9.08‰,深层第四系松散孔隙水δ^(2)H值和δ^(18)O值分别为67.6‰、δ^(18)O值,基岩岩溶水δ2H值和δ^(18)O值分别为64.5‰、9.36‰。基岩岩溶水稳定同位素含量均值与浅层地下水比较接近;浅层第四系松散孔隙水14C含量为46.7%~93.1%,深层水第四系松散孔隙水14C含量为40.23%~61.13%,基岩岩溶水14C含量为46.79%~89.2%,与浅层第四系松散孔隙水比较接近。通过分析研究掌握了北京平谷盆地地下水的循环演化规律,盆地第四系孔隙水和隐伏基岩岩溶水的水力联系,研究成果能够为平谷盆地地下水水文地质概念模型的建立、水文地质参数的初步确定、地下水资源计算评价提供技术支撑。Based on the analysis of groundwater isotope and water chemical sampling in the region,the evolution characteristics of groundwater circulation in the alluvial fan of Juhe and Ruhe rivers in Pinggu were studied.The analysis results show that the pH value of the water sample is between 7.6 and 8.2,which is neutral water.The cationic content is mainly Ca^(2+)and Mg^(2+),accounting for more than 70%,and the anionic content is mainly HCO_(3)^(–),accounting for more than 82%.The water chemical type of the groundwater samples is HCO3•Ca•Mg.In the study area,the stable isotope content of shallow quaternary loose pore water is(δ^(2)H:64.9‰,δ^(18)O:9.08‰),the meanstable isotope content of deep quaternary loose pore water is(δ^(2)H:67.6‰,δ^(18)O:9.97‰),and the stable isotope content of bedrock karst water is(δ^(2)H:64.6‰,δ^(18)O:9.36‰).The average stable isotope content of bedrock karst water is close to that of shallow groundwater.The 14C content of shallow quaternary loose pore water is 46.7%~93.1%,that of deep quaternary loose pore water is 40.23%~61.13%,and that of bedrock karst water is 53.7%~89.2%,which is close to that of shallow Quaternary loose pore water.Through the analysis and research to master the Beijing pinggu basin groundwater circulation evolution,basin quaternary pore water and concealed rock karst water hydraulic connection,research results for pinggu basin groundwater hydrogeological conceptual model and hydrogeological parameters of a preliminary determination,evaluation of groundwater re-sources calculation provides the technical support.

关 键 词：平谷盆地 水化学 2H 18O 水力联系 

分 类 号：P641.3[天文地球—地质矿产勘探]