榆神府矿区地下水水化学特征及形成机理

Hydrochemical characteristics and formation mechanism of groundwater in Yushenfu Mining Area

煤矿区地下水化学特征及其形成作用对矿区地下水保护和矿井突水水源识别具有重要意义。以陕北榆神府矿区第四系松散层、白垩系洛河组、侏罗系安定组及直罗组地下水为研究对象,综合利用统计分析、Piper三线图、同位素、Gibbs图及离子比例关系等方法分析了地下水水化学特征及形成作用。结果表明:研究区地下水均为弱碱性淡水,其中第四系松散层、白垩系洛河组和侏罗系直罗组风化基岩地下水中,阳离子以Ca^(2+)为主,阴离子以HCO_(3)-为主,侏罗系安定组地下水中阳离子以K^(+)+Na^(+)为主,阴离子以HCO_(3)^(-)为主,侏罗系直罗组正常基岩地下水中阳离子以K^(+)+Na^(+)为主,阴离子以SO_(4)^(2-)为主;各含水层地下水中TDS与主要离子相关性显著;白垩系洛河组与侏罗系直罗组正常基岩地下水中,离子空间分布差异性较大;通过同位素分析和溶滤作用分析,第四系与直罗组风化基岩含水层存在水力联系;研究区地下水主要离子形成受岩石风化控制,主要离子来源于碳酸盐、硅酸盐和硫酸盐矿物的溶解,并受到K^(+)、Na^(+)、Ca^(2+)、Mg^(2+)等阳离子交替吸附作用的影响。该研究结果可为榆神府矿区地下水资源保护和合理开发与利用等提供一定的借鉴。

The hydrochemical characteristics of groundwater in coal mining areas and its formation are of great significance to groundwater protection in mining areas and the identification of mine water inrush water sources. This paper takes the Quaternary aquifer, Cretaceous Luohe Formation, Jurassic Anding Formation and Zhiluo Formation aquifer groundwater as research objects in the Yushenfu Mining Area in northern Shaanxi. The chemical characteristics and formation of groundwater were analyzed by comprehensive use of statistical analysis, Piper’s three-line diagram, isotope, Gibbs diagram and ion ratio relationship. The results show that the groundwater in this mining area is weakly alkaline fresh water. In the groundwater of quaternary, cretaceous Luohe Formation and Jurassic Zhiluo Formation(weathered bedrock), the cation is mainly Ca^(2+), and the anion is mainly HCO_(3)^(-). In the groundwater of Jurassic Anding Formation, the cation is mainly K^(+)+Na^(+), and the anion is HCO_(3)^(-). In the groundwater of Jurassic Zhiluo Formation(normal bedrock), the cation is mainly K++Na+, and the anion is mainly SO_(4)^(2-). TDS in the groundwater of each aquifer is significantly correlated with major ions. In the normal bedrock groundwater of the Luohe Formation and the Jurassic Zhiluo Formation, the spatial distribution of ions was quite different.Through isotope analysis and dissolution analysis, there is a hydraulic connection between the fourth series and the weathered bedrock aquifer of the Zhiluo Formation. The formation of main ions in groundwater in the study area is controlled by rock weathering, and the main ions are derived from the dissolution of carbonate, silicate, and sulfate minerals, and are affected by the alternating adsorption of K^(+),Na^(+), Ca^(2+), and Mg^(2+)cations. The results of this study can provide some reference for the protection and rational development and utilization of groundwater resources in the Yushenfu Mining Area.