MONITORING A UNIQUE KARST SYSTEM OVER TWO-YEARS TO ELUCIDATE HYDROCLIMATE VARIABLES INFLUENCING THE GEOCHEMISTRY OF SURFACE AND SUBSURFACE WATERS
Our monitoring results demonstrate year-round cave ventilation and calcite growth in SBF Cave. Dripwater O and H isotope values deviate from the Global Meteoric Water Line consistent with evaporation, likely occurring in the epikarst, on the cave ceiling, or both. Co-variation of ln(Sr/Ca) and ln(Mg/Ca) in surface and subsurface waters is quantitatively accounted for by prior calcite precipitation (PCP). Subsurface waters are more PCP-evolved than surface waters. Co-variation between ln(Sr/Ca) and ln(Mg/Ca) of cave dripwaters, which is commonly used as an aridity proxy in stalagmites, might be a result of PCP occurring in both the watershed and the cave. Lastly, the water-calcite distribution coefficient of Mg for a site nearest to the cave entrance has a strong correlation with seasonal temperature variability (r2 = 0.67). Thus, we hypothesize that low/high Mg/Ca ratio couplets may aide in constraining seasonal geochemical cyclicity of near-entrance stalagmites. Taken together, we show processes in the watershed influencing the geochemical variability of cave dripwaters.