Karst Conduit Hyporheic Zone Exchange

喀斯特管道地下流交换约翰·l·威尔逊，新墨西哥矿业技术研究所这个项目将首次尝试测量喀斯特管道（地下水位以下的洞穴）边缘的地下流交换。地表溪流的潜流交换是一个相对较新的领域，但随着对流动污染物迁移、停留时间分布、生物地球化学和生物学的影响的实现，相关的出版物呈指数级增长。潜流带的一个定义是水从流进入的地下体积，穿过地下并返回流。无论沿河道有无净收益、净损失，甚至有无净交换，河流中的隐流带都存在于各种嵌套的时空尺度上。岩溶管道的基本流体动力学与河流没有什么不同，岩溶管道具有引起河流系统下隐流的相同特征。该项目将调查是否像河流一样，岩溶管道中发生了隐性交换，而不考虑与含水层的大规模净交换。岩溶管道的潜流交换及其相关的生物地球化学过程成为岩溶水循环的基本组成部分。该项目将在佛罗里达无承压含水层的一个潜水管道场址进行；此外，附近还会有一个充满空气的模拟地点，在过去的某个地质时期也经历过类似的过程。核心将从潜水和模拟地点取下。孔隙度、渗透率和岩石物理测量将被用作过去管道潜流的替代指标。潜水点的岩心孔将配备多级采样器和进样器，并进行一系列的染料痕迹观察岩溶管道的潜流。建模将在整个项目中使用，首先帮助规划现场工作，然后综合数据。数据和模型的结果将使我们深入了解隐性流动的时间和空间尺度。该项目将以建模作为预测工具来概括我们的结果。喀斯特含水层为美国25%的地区提供水源，并为某些地区提供几乎全部的水源，例如佛罗里达州90%的人口。新的数学模型和实地研究将用于阐明一个以前未被认识的过程，即在流动的喀斯特管道边缘的喀斯特潜流交换，在这个过程中，管道和周围的喀斯特岩石基质交换水，从而对喀斯特化学和生物学产生影响。与地表溪流的潜流交换一样，喀斯特潜流交换可能会影响供水、水质和生态，并将引起地方、州和联邦各级环境机构和利益团体的兴趣。

Karst Conduit Hyporheic Zone ExchangeJohn L. Wilson, New Mexico Institute of Mining and TechnologyThis project will attempt to measure, for the first time, hyporheic exchange at the margin of a karst conduit (cave below the water table). Hyporheic exchange in surface streams is a relatively new field, but related publications are growing exponentially as the implications for flow contaminant transport, residence time distributions, biogeochemistry and biology are realized. One definition of the hyporheic zone is the subsurface volume where water enters from the stream, travels through the subsurface, and returns to the stream. Hyporheic zones in streams exist at a variety of nested spatial and temporal scales whether there is net gain, net loss, or even no net exchange along the course. The fundamental fluid dynamics of karst conduits are not different from streams, and karst conduits have the same features that cause hyporheic flow in fluvial systems. This project will investigate whether, as with streams, hyporheic exchange occurs in karst conduits, regardless of larger-scale net exchange with the aquifer. Karst-conduit hyporheic exchange, and related biogeochemical processing, then becomes a fundamental component of the karst water cycle. The project will be conducted in a phreatic conduit field site in the unconfined Floridan Aquifer; additionally there will be a nearby air-filled analog site that was exposed to similar processes at some time in the geologic past. Cores will be taken from the phreatic and analog sites. Porosity, permeability, and petrophysical measurements will be used a proxy indicators of past conduit hyporheic flow. The core holes at the phreatic site will be equipped with multilevel samplers and injectors, and a series of dye traces will be conducted to observe karst-conduit hyporheic flow. Modeling will be used throughout the project, first to help plan the field work and then to synthesize the data. Results from the data and models will give insights into the temporal and spatial scales of hyporheic flow. The project will end with modeling as a predictive tool to generalize our results.Karst aquifers supply water to 25% of the United States, and almost all water to some regions, e.g. 90% of Florida's population. New mathematical models and field studies will be used to illuminate a previously unrecognized process, karst hyporheic exchange at the margin of a flowing karst conduit, in which the conduit and surrounding karst rock matrix exchange water with consequences for karst chemistry and biology. As does hyporheic exchange in surface streams, karst hyporheic exchange may impact water supply, water quality, and ecology, and will be of interest to environmental agencies and interest groups at the local, state and federal level.