江汉平原西缘地下水水文地球化学过程研究

鄂西丘陵山区地下水向江汉平原运移是较复杂的水文地球化学过程,通过数理统计、水化学分析、Gibbs图以及水文地球化学模拟等方法对江汉平原西缘不同类型地下水运动及其化学组分变化规律进行了研究。结果表明:裂隙岩溶水主要化学类型为HCO_3-Ca和HCO_3-Ca+Mg型,碎屑岩类裂隙水为HCO_3-Ca和HCO_3-Ca+Na型,孔隙水以HCO_3-Ca型为主。方解石和白云石的溶解是丘陵山区主要的水文地球化学过程,孔隙水和裂隙水以岩盐和石膏的溶解为主,裂隙水中还存在阳离子交换吸附作用,少量孔隙水受蒸发-沉淀作用的影响。地下水由丘陵山区向平原区径流过程中发生了石膏以及少量岩盐和钾长石的溶解,同时伴随着阳离子交换吸附和硝化反应,方解石和少量的钠长石因为过饱和而发生沉淀。

Hydro-geochemical process of groundwater in western margin of Jianghan Plain

The groundwater migration from hilly area of western Hubei Province to Jianghan Plain is a complex hydro-geochemical process. This paper studies the movement and chemical composition variation of groundwater in western margin of Jianghan Plain by mathematical statistics, water chemistry analysis, Gibbs diagram and hydro-geochemical simulation. The results show that the major chemical types of fissure karstic water are HCO3-Ca and HCO3-Ca+Mg, fissure water in cataclastic rocks are HCO3-Ca and HCO3-Ca+Na, pore water is HCO3-Ca. The dissolution of calcite and dolomite is the dominant hydro-geochemical process in hilly area. The pore water and fissure water are mainly affected by dissolution of halite and gypsum. Cation exchange adsorption occurs in fissure water, and a small amount of pore water is affected by evaporation-precipitation. The gypsum and a small amount of halite and potassium feldspar are dissolved during the migration of groundwater from hilly to plain, accompanied by cation exchange adsorption, nitrification reaction and precipitation of oversaturated calcite and a small amount of albite.