RATES OF INORGANIC CARBON FLUX IN THE KARST AQUIFERS OF THE APPALACHIAN LOWLAND PLATEAUS

Monitoring data and water samples collected in 2010–2011 from the Redmond Creek karst aquifer developed within Paleozoic carbonates of the southeast Kentucky are combined with GIS data on carbonate rock exposure from the Kentucky Geological Survey to evaluate the variation and magnitude of flux of dissolved inorganic carbon (DIC) within karst landscapes in the Cumberland River watershed of southeast Kentucky and the global scale. Geochemical modeling using measured ionic species, the carbonate equilibrium equations, and the modeled discharge reveal a variable rate of DIC flux driven by large by fluctuations in calcite saturation and discharge. The data suggest that upwards of 9% of the bedrock dissolution in the Redmond Creek karst aquifer may be driven by the oxidation of reduced sulfur derived from shallow brines entrained into the active flow system. Over the 3.73x10⁵ ha of carbonate exposure within the Cumberland River of southeast Kentucky, 438 Gg/yr of CO₂ are captured from the atmosphere and soil through the dissolution of carbonate rocks. At the global scale, this translates to 207 Tg/yr of CO₂ sequestered by karst processes into the aqueous system.