汉中天坑群小南海岩溶水水化学特征及其指示意义

The hydrogeochemistry of karst water from Xiaonanhai in Hanzhong Tiankeng groups and its indicating significance

以小南海岩溶水为研究对象,通过分析水化学和氢氧同位素数据,确定岩溶水中主要物质组分来源及补给径流特征,对岩溶水的合理开发利用及生态环境保护具有重要意义。结果显示:所有水样均为弱碱性、低矿化度水,水化学类型以HCO_(3)-Ca型为主;岩溶水溶质组分受控于岩石风化作用,主要来源于碳酸盐岩类和部分硫酸盐岩类矿物溶解,此外还受人类活动影响;吴家坪组、阳新组、仙女洞组岩溶水以流经灰岩含水层为主,大冶组岩溶水流经灰岩和白云岩含水层。氢氧同位素特征指示岩溶水均源于不同海拔大气降水的混合补给,降水入渗补给前,岩溶水受到的蒸发作用强于地表水。水化学特征和氘过量参数揭示小南海岩溶水系统径流条件好,溶滤作用较强,双龙洞岩溶水系统径流条件好,溶滤作用较弱。

The data of hydrogen and oxygen isotopes and hydrochemistry in Xiaonanhai were analyzed to reveal material sources and the characteristics of recharge-runoff in karst water,which was of great significance to rational utilization of karst water and ecological environment protection.The results of hydrochemical study show that water samples were mainly HCO_(3)-Ca type with weakly alkaline and low salinity;The solute composition of karst water controlled by water-rock interaction was mainly from the dissolution of carbonate minerals and partly from the dissolution of sulphate minerals,the karst water was also affected by human activities;The karst water of Wujiaping formation,Yangxin formation and Xiannvdong formation mainly flowed through limestone aquifer while the karst water of Daye formation flowed through limestone and dolomite aquifer.The results of hydrogen and oxygen isotopes study show that karst water came from the mixed recharge of atmospheric precipitation at different altitudes,the evaporation concentration of karst water before rainfall infiltration was stronger than that of surface water.Hydrochemical characteristics and deuterium excess parameter revealed that the karst water system in Xiaonanhai had good runoff conditions and strong leaching,while the karst water system in Shuanglongdong had good runoff conditions and weak leaching.