雪玉洞岩溶地下水、地表水Ca2+、Mg2+、Sr2+变化特征研究

通过2011年对重庆丰都雪玉洞洞内滴水和地下河河水，上覆岩层中出露的表层岩溶泉水和雪玉洞附近龙河河水等不同类型水中Ca2＋、Mg2＋、Sr2＋抖浓度及Mg／Ca、Sr／Ca值的研究，发现不同水的Ca2＋、Mg2＋、Sr2＋随外界降水条件的改变而出现明显变化。表层岩溶泉水Ca抖变化能够敏感反应外界降水条件改变，滴水对外界降雨的反应滞后接近1个月，地下河Ca2＋可以反应雨季和旱季的变化，地表河水Ca2＋全年比较稳定，但是对特殊干旱天气有显著响应。2011年不同类型水的Ca2＋、Sr2＋全年变化趋势基本一致，在降水较多的3、5、10月呈低值，在其他降水较少的月份浓度相对较高。各离子的这种变化特征主要是受到稀释效应、CO：效应以及所在地层的岩性的影响。雪玉洞不同类型水的Mg／Ca、Sr／Ca值呈现出滴水〉地表河〉地下河〉表层岩溶泉的特点，反映出不同类型水在含水介质中滞留时间的长短，并且Mg／Ca、Sr／Ca值在降水较多的月份降低，在降水较少的月份升高；受碳酸钙的前期沉淀和运移路径差异的影响，不同类型水的Mg／Ca、Sr／Ca值变化稍有不同。因此，不同类型水的离子变化及其比值对外界降水条件变化的响应特征和时间的不同，决定了在利用元素及其比值反映外界环境变化时也要区别对待。

Variations of Ca2＋ ,Mg2＋ ,Sr2＋ in groundwater and surface water from the Xueyu cave

A one-year study of water geochemistry was performed in the Xueyu cave in 2011, the concentra- tions of Ca2 , Mg2＋ ,St2 and elemental ratios of Mg/Ca,Sr/Ca in drip water, groundwater and epikarst spring water from the overlaying bedrock as well as the surface water from the Long River were measured. The results indicate the variation of Ca2＋ ,Mg＋ ,Sr2＋ along with the precipitation was notable. The Caz in epikarst spring water can response with the change of precipitation sensitively. The drop water responses to the change of precipitation may last for a month. The rainy season and the dry season can be reflected by the underground water. The content of Ca＋f in the surface water was stable all year round but had pronounced reflection to extreme dry weather. The variations of Mg2 and Sr2＋ in different types of water were consist- ent with each other yearly in 2011, and the concentrations of Mg2＋ and Sr＋ were lower in March, May and October with much rainfall, but higher in other months with little rainfall. The above changes in cation con- centrations were related to the dilution effect, COz effect and lithology. The ratios of Mg/Ca and Sr/Ca in different kinds of waters from the Xueyu cave system ranged from high to low as follows： drip water, surface water, ground water and spring water, reflecting different detention time in the aquifer media and reacting time with bedrock. The ratios of Mg/Ca and St/Ca were low during wet period and high during dry period. For the impact of the former calcium carbonate precipitation and the variance in transport routes, there are slight differences in the ratios of Mg/Ca,Sr/Ca. Therefore, the change of ions concentration and their ratios in different types of water is different in the responding time and features to external precipitation, which de- ciding that it should make difference when determining external environmental changes with the elements and their ratios.