双河洞流域氢氧同位素特征及其指示意义

Hydrogen and Oxygen Isotope Characteristics and Their Indicative Significance in Shuanghe Cave Basin

为了探究喀斯特区域地表水与地下水的相互转化关系及水-岩作用特征,以双河洞流域为研究对象,分别在2018年12月和2019年6月对流域地表水与地下水进行监测采样。运用数理统计、Piper三线图、回归分析等方法对水样的氢氧同位素组成和水化学特征进行分析。结果表明:(1)旱季和雨季流域内地表水、地下水优势阳离子以Ca^(2+)和Mg^(2+)为主,优势阴离子以HCO_(3)^(-)为主;水化学类型为Ca^(2+)·Mg^(2+)-HCO_(3)^(-)型。(2)流域内氢氧同位素具有季节变化特征,表现为雨季高、旱季低;流域沿程有着复杂的转换关系,池武溪上游以地下水补给地表水为主,池武溪中游至下游地表水与地下水交替补给。(3)流域氘盈余值呈现出旱季低雨季高的季节差异,在水-岩作用的影响下与当地大气降水的氘盈余值变化特征相反,而且水-岩作用强烈的区域与流域洞穴密集分布的特点相对应。

In order to explore the mutual transformation relationship between surface water and groundwater and the water-rock interaction characteristics in the Karst region,the Shuanghe cave watershed was taken as the research object.The surface water and groundwater in the watershed were monitored and sampled in December 2018 and June 2019,respectively.The hydrogen and oxygen isotopic composition and hydrochemical characteristics of water samples were analyzed by means of mathematical statistics,Piper trigram and regression analysis.The results showed that:(1)Ca^(2+)and Mg^(2+)were the dominant cations in surface water and groundwater,and HCO_(3)^(-) was the dominant anion in the dry season and rainy season.The hydrochemical type was Ca^(2+)·Mg^(2+)-HCO_(3)^(-).(2)Hydrogen and oxygen isotopes in the basin have seasonal variation characteristics,with high values in rainy season and low values in dry season;There is a complex transition relationship along the river basin.The surface water of upper reaches of Chiwuxi are mainly replenished by ground water,and the surface water and ground water are replenished alternately from the middle reaches to the lower reaches of Chiwuxi.(3)The deuterium excess of the basin presents a seasonal difference of low in dry season and high in rainy season,which is opposite to the deuterium excess of local precipitation under the influence of water-rock interaction,and the regions with strong water-rock interaction correspond to the characteristics of intensive distribution of caves in the basin.