白云岩洞穴系统中水-气CO_2分压对洞穴水水文化学过程的影响:以贵州双河洞为例

Effects of Partial Pressure of CO_2 of Water/gas on Hydro-chemical Process of Cave Water:a Case Study in Dolomite Cave System of Shuanghe Cave in Guizhou Province

为揭示白云岩岩层中所发育洞穴系统中的中的洞穴水与空气中CO_2分压对洞穴水水文化学过程的影响及其动态变化特征和控制因素。从2015年4月至9月对绥阳双河洞洞穴水的水化学指标进行了为期6个月的动态监测,结果表明:(1)双河洞洞穴水的水化学类型主要为HCO_3^--SO_^(2-)-Ca^(2+)-Mg^(2+)和SO_4^(2-)-HCO_3^--Ca^(2+)-Mg^(2+)型水,在受到上覆石膏岩层的影响时,SO_4^(2-)成为优势离子且可以极大提高溶液中Ca^(2+)离子含量;(2)洞穴滴水的水-气间CO_2分压差值(△PCO_2)与SI之间存在良好的负相关关系的同时,2种重要的矿物饱和指数SI_c,SI_d之间存在着良好的正相关关系;(3)实测数据分析证明"表观饱和指数"现象的客观存在;(4)洞穴水中的液相CO_2(PCO_2_(water))与溶液的pH值呈现出显著的负相关关系,且在未开发的天然封闭洞腔中洞穴空气CO_2分压对洞穴水水文地球化学过程影响较小。

In order to explore the effects of cave water in the dolomite-strata-developed cave system and CO2 partial pressure of atmosphere on cave water hydro-chemical process and its dynamic characteristics as well as control factors, the dynamic monitoring was conducted for a period of 6 months from June to September 2015, with respect to the water chemistry indices of cave water in Shuanghe Cave. The results of the monitoring indicated that hydro-chemical types of Shuanghe cave-water were mainly HCO3-Ca2＋-Mg2＋ and SO42-HCO3-Ca2＋-Mg^2＋, and when influenced by overlying gypsum strata SO4^2- would become dominant ions thus greatly increasing Ca2＋ ion content. There was a good negative correlation between APCO2, the CO2 partial pressure difference between drip water and gas phase, and Sic, while at the same time, there existed a good positive correlation between Sic and SId, the two important mineral saturation indices. The objective existence of the phenomenon of apparent saturation index was proved by the analysis of the measured data; and Significant negative correlation existed between the liquid phase CO2 （PCO2 （waicr）） of cave-water and pH value of the solution, and the influence of the CO2 partial pressure of the cave air in natural intact closed cavity on the cave water was comparatively small.