江汉平原西部浅层孔隙水水文地球化学特征

为了揭示地下水由江汉平原周缘向中心径流过程中的水质演化和复杂的水文地球化学作用,以江汉平原西部地区为例,通过数理统计、水化学、同位素地球化学、离子比值关系等方法,开展了江汉平原西部边缘地带浅层孔隙地下水的水文地球化学特征研究。结果表明: 平原区孔隙水以HCO₃-Ca·Mg型为主,丘岗区(丘陵和岗地)主要是HCO₃-Ca·Mg型,少量为HCO₃·SO₄-Ca·Mg型,还出现了HCO₃·NO₃-Ca·Mg型水,总溶解固体(total dissolved solids,TDS)升高主要是由于碳酸盐岩的溶解; 浅层孔隙水均来源于大气降水,蒸发作用对该地区孔隙水的影响较小; 方解石、白云石和石膏的溶解主导研究区的水文地球化学过程,也是孔隙水中Ca²⁺、Mg²⁺的主要来源,Na⁺和K⁺的主要来源是阳离子交换吸附。

Hydrogeochemical characteristics of the shallow pore water in Western Jianghan Plain

Western Jianghan Plain was taken as an example to reveal the migration of groundwater from periphery to the center of Jianghan Plain and complex hydrogeochemical action. Hydrogeochemical characteristics of the shallow pore water in the margin of Western Jianghan Plain were studied by the methods of mathematical statistics, water chemistry, isotope geochemistry and relationships between ions and so on. The results showed that HCO₃-Ca·Mg is the dominant chemical types in flat country. HCO₃-Ca·Mg is the dominant chemical types in hilly and mound land, with small amount HCO₃·SO₄-Ca·Mg. Besides, the HCO₃·NO₃-Ca·Mg is also existent in hilly and mound land and the increasing total dissolved solids is due to the dissolution of carbonate rocks. Shallow pore water is mainly from atmospheric precipitation, and barely influenced by evaporation. The dissolution of calcite, dolomite and gypsum is the dominant hydrogeochemical process, and they are the main source of Ca²⁺ and Mg²⁺. The main source of Na⁺ and K⁺ is by cation exchange adsorption.