Hydrologic and microclimate characterizations of Thornton's Cave, West-Central Florida (USA)

Abstract

Abstract. A cave's subsurface environment is controlled by a suite of factors unique to the surrounding environment in which the cave formed, including, but not limited to, regional geologic, and climate settings. These factors collectively owe to wide variations in cave biology, geomorphology, and overall speleogenesis. This report combines local climate, hydro-logic, and CO 2 data collected over the course of a two-year study at Thornton's Cave, a partially-flooded cave in the West-Central Florida karst belt, to characterize its current environment and yield insight regarding how changes in regional climate and hydrology impact its past and future speleogenesis. Data loggers continuously monitoring cave and surface air temperatures, water levels and surface rainfall documented immediate responses in the cave to long-and short-term fluctuations in these parameters at the surface. Atmospheric CO 2 in the cave and at the surface demonstrate seasonal trends, though the cave maintains higher concentrations and lower δ 13 C of CO 2 than the surface, suggesting decomposition of organic matter, and to a lesser degree macroorganisms are contributing proportionally more CO 2 to the cave. Collectively, these interpretations provide insight on the impact of surface processes on cave formation here, and suggest that a biotic model of speleogenesis using bacterially-sourced CO 2 as a component of dissolution may be possible. Further, they can be used to further the understanding of the karstification in West-Central Florida and analogous karst regions.