SEASONAL TREND OF DISSOLVED GREENHOUSE GAS CONCENTRATIONS IN RURAL KARST GROUNDWATER SYSTEMS IN SOUTH-CENTRAL KENTUCKY

Greenhouse gases (GHGs) are a major global environmental concern, because their concentrations have continuously risen over the past few centuries, due to global population growth, fossil fuel dependency, and the industrial revolution. Since these gases are natural occurring phenomena, they will never be completely eliminated. Efforts to reduce them span across numerous scientific attempts with minimal improvements in reducing their atmospheric concentrations. In agricultural land practices, greenhouse gases are common byproducts that affect the atmosphere and groundwater. Little is known about the movement of greenhouse gases is a karst environment and by studying seasonal trends in an agricultural karst landscape, measurement of how a karst system contributes to the cycling of dissolved greenhouses can be measured. Crumps Cave in Smiths Grove, Kentucky, provides a research site with two wells drilled to a depth of 15 and 50 meters, into the epikarst aquifer and deeper regional aquifer, respectively. Seasonal monitoring of the wells, along with an epikarst waterfall that flows inside the cave, was conducted for dissolved greenhouse gas emissions, as well as other geochemical parameters and bacteria. Methagens, methatrophs, nitrifiers and, denitrifiers were measured by DNA extractions to determine if trends of greenhouse gas concentrations varied between the sites and over varying timescales. Preliminary data over the past nine months indicate substantial differences between the wells, but possibly connections of epikarst and aquifer processes with respect to GHG migration through the system. It is important to consider the implications of concentrations of GHGs within the hydrologic system, since manure spreading or nitrogen application may impact the long-term cycle of GHGs.