Speleogenesis and Evolution of Karst Aquifers The Virtual Scientific Journal www.speleogenesis.info Preliminary investigations of seasonal changes in the geochemical evolution of the Logdson River, Mammoth Cave, Kentucky

Many geochemical studies have been made of karst waters worldwide. Most data that provide the framework for our current understanding of the evolution of karst waters have come from sampling at discrete times and locations, such as springs or wells. Relatively few studies have been made of the geochemical evolution of groundwater as it moves through an open flow system. This paper addresses the seasonal changes in the geochemistry of the Logsdon River conduit as it passes through nearly 10km of the carbonate aquifer of south-central Kentucky. The most important control on the ability of groundwaters to dissolve limestone is their carbon dioxide pressure, which is influenced by a variety of complex interactions with soil, bedrock, and in-cave organic decay. The fieldwork involved in this research combines seasonal sampling of the entire traversable length of the Logsdon River conduit, as well as continuous monitoring of the chemistry at key points within the flow system. Preliminary results of this study indicate both seasonal changes in CO2, transport through the Mammoth Cave karst aquifer during summer and winter conditions, along with significant geochemical changes as the water moves through a distance of 10km