Surface and ground water mixing, flow paths, and temporal variations in chemical compositions of karst springs

Karst aquifers provide important sources of water, but may be susceptible to contamination from mixing with polluted surface water. Characteristics of mixing, in particular the extent of conduit versus diffuse flow, have been studied through time-series observations of the chemical composition of water discharging from springs (chemographs). Annual and storm chemographs of Ca, Mg, DIC, and alkalinity are constant within error for six closely spaced springs that discharge from the Floridan aquifer in north-central Florida, reflecting equilibration with carbonate rocks of the aquifer. Similar chemographs from other karst aquifers have been interpreted to reflect diffuse flow, but dye trace and cave diving…