Liang Sha, Yang Yan, Zhang Na, Sun Zhe, Zhang Ping, Tian Ning, Ling Xin-You, Ren Xiao-Min
Chongqing Key Laboratory of Karst Environment, School of Geographical Sciences, Southwest University, Chongqing, 400715, China.
Field Scientific Observation & Research Base of Karst Eco-environments at Nanchuan in Chongqing, Ministry of Land and Resources of China, Chongqing 408435, China.
Huan Jing Ke Xue. 2017 Oct 8;38(10):4130-4140. doi: 10.13227/j.hjkx.201703140.
To explore the temporal and spatial variations and the process of trace element migration in the karst critical zone, continuous fixed-point monitoring and sampling analysis was applied to measure each cave system component, which includes rainfall, soils, bedrock, drip waters, and their aerial sediment. Approximately 650 experimental data were obtained from October 2009 to May 2015 in a typical karst critical zone in north China-an interactive zone of the Jiguan Cave in the west Henan Province. The variations in and the migration rules of Ca, Mg, Ba, Sr, and δC as well as their ratios to different components were studied. The results show that:① Soil and bedrock are the main sources of drip water. The values of Mg, Ba, and Sr are consistent with the "soil-bedrock" two end-members model and their respective proportions are 43.6:56.4, 1.01:98.09, and 47.2:52.8. ② From the spatial perspective, element migration of each component in the cave system interactive zone is interrelated. Drip water inherits the signals of the soil and bedrock and the modern sediment can continue the element information of the drip water. Elements in the soil profile cause the leaching and deposition effect and the subsoil better inherits the information of trace elements in the bedrock. ③ From the temporal perspective, the migration of elements in the cave system interactive zone is complex. Because of the leaching effect, soil and drip water show obvious seasonal discrepancies. However, under the influence of karst water migration path, the prior calcite precipitation (PCP), and extreme arid and annual precipitation type, the seasonal discrepancy in the element concentrations in drip water is smaller than in soil. The PCP effect, selective leaching, and other factors change the continuity of elements released from sediment to drip water. ④ In order to systematically and comprehensively ascertain the trace element migration in the karst critical zone and energy transformation rules, the study of cave system should be based on the research of the cave's critical zone and should consider comprehensive information ranging from the atmospheric origins to secondary sediments.
为探究喀斯特关键带中微量元素的时空变化及迁移过程，采用连续定点监测与采样分析方法对洞穴系统各组成部分进行测量，包括降雨、土壤、基岩、滴水及其大气沉积物。2009年10月至2015年5月期间，在中国北方典型喀斯特关键带——豫西鸡冠洞的一个交互带获取了约650组实验数据。研究了Ca、Mg、Ba、Sr、δC及其与不同组分的比值的变化和迁移规律。结果表明：①土壤和基岩是滴水的主要来源。Mg、Ba和Sr的值符合“土壤 - 基岩”二元端元模型，其各自比例分别为43.6:56.4、1.01:98.09和47.2:52.8。②从空间角度看，洞穴系统交互带中各组分的元素迁移相互关联。滴水继承了土壤和基岩的信号，现代沉积物能够延续滴水的元素信息。土壤剖面中的元素产生淋溶和沉积效应，亚表层土壤更好地继承了基岩中微量元素的信息。③从时间角度看，洞穴系统交互带中元素的迁移较为复杂。由于淋溶作用，土壤和滴水表现出明显的季节差异。然而，在岩溶水迁移路径、前期方解石沉淀（PCP）以及极端干旱和年降水类型的影响下，滴水中元素浓度的季节差异小于土壤。PCP效应、选择性淋溶等因素改变了沉积物向滴水释放元素的连续性。④为系统全面地确定喀斯特关键带中微量元素的迁移及能量转换规律，洞穴系统研究应基于洞穴关键带的研究，并应考虑从大气源到次生沉积物的综合信息。
