Doctoral Dissertation Research: Hydrologic and Geochemical Response of Conduit- and Diffuse-Flow Karst Systems to Variable Seasonal Climate and Individual Storm Characteristics

当地下水溶解石灰岩、白云岩或其他可溶岩石时，喀斯特地貌主要通过溶解过程而形成。岩溶研究面临的最重要的问题之一是，为什么潮湿的热带喀斯特地形比凉爽环境的喀斯特景观更突出，地貌风格更多样。不同的发育阶段、气候、土壤中的二氧化碳、地质结构和岩性以及径流都被认为是原因。这项博士论文研究项目将通过对两种不同类型的含水层的分析，来研究含水层的水文和地球化学特征在地下水去除物质方面所起的作用。田纳西州东南部的Lost Cove有一个含水层，含水层以高度集中的管道为主，地下水通过这些管道流动，而佐治亚州西北部口袋支流山谷的地下水运动则通过含水层高度扩散。将在两个研究区建立环境监测站网络，通过自动传感器或重复野外观测定期记录气候、水文和土壤水化学。将对使用这些监测仪收集的数据进行分析，以更全面地确定管流岩溶系统和扩散流岩溶系统之间的主要水文和地球化学差异，以应对季节性气候变化和个别风暴。结果将有助于确定哪个流动系统更快地去除材料，并将解释为什么以及何时发生去除。这项研究还应该有助于确定哪个系统吸收了更多的碳，从而增加了其作为缓冲大气中二氧化碳增加的能力。作为博士论文研究改进奖，该奖项还将提供支持，使有前途的学生建立一个强大的独立研究生涯。

Karst landscapes develop predominately through processes of solution, as ground water dissolves limestone, dolomite, or other soluble rocks. One of the most significant questions confronting karst studies is why humid tropical karst terrains are more accentuated and more varied in landform styles than are karst landscapes of cooler environments. Different stages of development, climate, carbon dioxide in soils, geologic structure and lithology, and runoff all have been suggested as explanations. This doctoral dissertation research project will examine the role that the hydrologic and geochemical characteristics of aquifers play in the removal of material by ground water through the analysis of two different kinds of aquifers located in close proximity to each other. The Lost Cove of southeastern Tennessee has an aquifer dominated by highly concentrated conduits through which ground water flows, while ground water movement in the Pocket Branch valley of northwestern Georgia is highly diffused through the aquifer. Networks of environmental monitoring stations will be established in the two study area, with regular records of climate, hydrology, and soil and water chemistry taken by automatic sensors or through repeated field observations. The data collected with these monitors will be analyzed to more fully define the major hydrologic and geochemical differences between conduit-flow and diffuse-flow karst systems in response to seasonal climate variations and individuals storms. The results will help identify which flow system removes material more rapidly and will explain why and when removal occurs. This research also should help determine which system sequesters greater amounts of carbon, thereby increasing its capacity to serve as a buffer against increasing carbon dioxide in the atmosphere. As a Doctoral Dissertation Research Improvement award, this award also will provide support to enable a promising student to establish a strong independent research career.