COMPARISON OF SUBMARINE GROUNDWATER DISCHARGE FLUXES IN GEORGIA TIDAL CREEKS USING RADON

Groundwater discharge fluxes are known to be spatially and temporally variable. They are also known to impact the biology of the receiving areas. We have been studying these variations, in addition to water chemistry to assess potential correlations between groundwater discharge and eastern oyster (Crassostrea virginica) beds. We collected groundwater and estuary samples from four recreational oyster harvesting creeks along the Georgia coast. Oyster Creek near Tybee Island, Jointer Creek near Jekyll Island, Medway River between Ossabaw and St. Catherines Islands and Teakettle Creek near Sapelo Island were surveyed between July and October 2018. We collected pore water samples using peristaltic pumps connected to push-point piezometers driven to ~50 cm depth at locations above the low-tide line from each creek bank to determine the concentration of radon in the groundwater end-member. Groundwater discharge was surveyed from surface waters using a commercially available radon detector (RAD-7), which monitors for radon-222, a well-established tracer of groundwater discharge. In the lab, we analyzed creek bank samples within three days and corrected for humidity and decay. The survey data was processed using a transient-state mass balance box model. Groundwater discharge fluxes and oyster health parameters will be compared in the future to determine how groundwater impacts oyster growth in Georgia’s recreational harvest areas.