The hydrologic record of karst systems: linking soil moisture to the carbon isotope signatures of soils above the Blue Spring cave system

Speleothem carbonates are precipitated continuously from inorganic carbon dissolved in seepage water infiltrating from the land surface, that reflects a mixture of atmospheric CO 2 , respired soil carbon, and epikarst sources, each with distinct δ 13 C values. To aid in deconvolving these signatures, soil samples were collected above the Blue Spring cave system in Sparta, Tennessee, USA and subjected to a series of incubation experiments, in order to constrain the correlation between CO 2 respiration rates and soil moisture. This relationship is used to parameterize a simple mixing model which predicts the relationship between δ 13 C and soil moisture in fluids infiltrating into the underlying cave system.