Collaborative Research: A new classification system for karst springs using storm hysteresis

岩溶含水层是一种重要的地下水资源，但由于地下洞穴和大型裂隙形成的快速而复杂的流动路径，它们很容易受到污染。长期以来，岩溶含水层的复杂性给研究人员描述地下水流动系统带来了挑战。该项目将开发一种新的岩溶泉水分类方法，以指导监测和污染防治战略。基于对风暴的水化学变化，这一分类将识别不同的水源，并改善水捕集区的划定。新的分类系统将通过重新考察一组著名的岩溶泉水来测试，这些泉水显示了水流路径的变化。该项目纳入了为学生和公众提供的教育机会。分类将基于磁滞回线的形状和磁滞回线从风暴到风暴的变化。风暴滞后，定义为风暴开始和结束时化学趋势的差异，为确定岩溶网络中水的运动和存储随时间的变化提供了机会。该项目将检验两个假设。(1)在风暴期间，当水流经基质和管道时，会发生滞后；(2)在风暴之间，滞后模式会随着集水区和蓄水区的变化而改变。例如，泉水中的镁钙比随着扩散补给的增加而增加，但随着管道补给的集中而减少，滞后曲线可以显示每种补给的时间。风暴期间将使用自动采样器和数据记录器为磁滞图提供数据。除了镁钙比外，还将研究锶钙比、稀土元素、稳定同位素和碳酸盐平衡，并将使用地下水模型评估潜在的流动路径。多种自然示踪剂、模拟和捕获面积计算的组合将有助于量化岩溶泉水和岩溶含水层的行为。最终，新的分类系统将提高对污染物在岩溶系统中运移的理解。

Karst aquifers are an important groundwater resource, but they are vulnerable to contamination because of fast and complex flow paths arising from subsurface caves and large fractures. The complexity of karst aquifers has for a long time imposed challenges for researchers to characterize the groundwater flow system. This project will develop a new classification method for karst springs that will guide monitoring and pollution prevention strategies. Based on water chemistry variability in response to storms, this classification will identify different sources of water and improve water capture area delineation. The new classification system will be tested by revisiting a well-known set of karst springs that show variations in flow paths. Educational opportunities for students and for the general public are incorporated into the project. Classification will be based on the shape of hysteresis plots and changes in hysteresis plots from storm to storm. Storm hysteresis, defined as the difference in chemical trends at the beginning versus the end of a storm, offers opportunities to identify changes over time in water movement and storage in karst networks. The project will test two hypotheses. (1) During a storm, hysteresis occurs as the water flows through the matrix and conduits, and (2) from storm to storm, the hysteresis pattern changes as the water capture area and storage zones change. For example, Mg:Ca ratios in spring water increase with diffusive recharge but decrease with more focused recharge through conduits, and hysteresis plots can show the timing of each type of recharge. Automatic samplers and data loggers will be used during storms to provide data for hysteresis plots. In addition to Mg:Ca ratios, Sr:Ca ratios, rare earth elements, stable isotopes, and carbonate equilibria will be examined and potential flow paths will be evaluated using groundwater models. The combination of multiple natural tracers, modeling, and capture area calculations will help quantify behavior of karst springs and karst aquifers. Ultimately, the new classification system will improve understanding of contaminant transport in karst systems.