Understanding the migration mechanism of karst water and the source of elements in the cave drips are the prerequisites for the retrieval of paleoenvironment by speleothem.In order to investigate the characteristics of cave drip in response to rainfall and the composition source of element in drip,in this study Ca,Mg,Sr and Ba elements in the overlying soil and bedrock of Shijiangjun Cave in Anshun region of Guizhou Province was analyzed and observation on the rainfall response of three drip points in the cave was carefully conducted.Results showed that due to the development of rocky desertification,the reaction of drips to rainfall in Shijiangjun Cave got faster,and ion concentration increased correspondingly with rainfall response.The existence of fracture,vadose,corrosion,water-rock interaction in overlying soil or bedrock contributed to the irregular variation of drip composition after rainfall.The reaction of Ca2+ and Mg2+ to rainfall was 12 h respectively.At drip point A,Ba2+and Sr2 + had response time 30 h.At drip point B,Ca2 +,Mg2 +,Sr2 +,Ba2 + were within 3 h but 24 h at drip point C.In response to rainfall,the hydrodynamic action types of the three drip points and those of elements exhibited distinct temporal and spatial variation,suggesting a noticeable difference of elemental origin at each drip point.Ba and Sr in drips during rainfall were mainly derived from bedrock,and the sources of Ca and Mg were controlled by the development degree of the overburden soil above the drip points.With the thicker the soil layer,Ca,Mg elements in drips received more supply from soil above whereas Ca,Mg were attributed more to bedrock as soil layer grow thinner.The response of cave drips to rainfall would provide an important scientific insight for using speleothem to retrieve the evolution of rocky desertification environment.%探明洞穴岩溶水的运移机制与滴水元素的成分来源,是利用沉积物元素反演古环境研究的前提.本研究对贵州安顺地区的石将军洞上覆土壤、基岩样品中的Ca、Mg、Sr、Ba元素进行分析,以及对洞穴中3个滴水点的元素进行了降雨响应监测,分析了洞穴滴水的降雨响应特征及其元素的成分来源.结果表明:受地表石漠化发育影响,石将军洞滴水对大气降雨响应时间较快,且各离子浓度随降雨响应相应升高;3个滴水点在降雨响应中的水动力作用类型与元素的时空变化差异较大,体现出每个滴水点的元素来源差异;滴水在降雨响应中的Ba、Sr元素主要来源于基岩,Ca、Mg元素来源受制于滴水点上覆土壤的发育程度,土壤层越厚,滴水Ca、Mg元素受到土壤的贡献越多,土壤层越薄,滴水Ca、Mg元素受到基岩的贡献越多.洞穴滴水的降雨响应研究为利用沉积物反演石漠化环境演变过程提供了重要的科学依据.
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