TEMPORALLY RESOLVED DISSOLVED ORGANIC CARBON DYNAMICS IN A GEORGIA SALTMARSH

Dissolved organic carbon (DOC) is one of the largest and most ecologically relevant pools of carbon in the world. The Georgia coast houses some of the world’s most productive saltmarshes, and while the productivity of these marshes is well established, there is a lack of long term dynamic organic carbon studies in Georgia’s tidal saltmarsh systems. Furthermore, there is little agreement on the net balance of carbon exchange between saltmarshes and the adjacent estuarine system, raising the question: do Georgia saltmarshes outwell organic carbon, and if so, how does carbon export vary throughout the year? To address this question, Groves Creek, a saltmarsh on Skidaway Island, GA was monitored for 18 months between 2013 and 2015. Over this time, an in situ spectrophotometer captured colored-DOM attenuation every 15 minutes while additional water was autosampled 14x/tidal cycle every two weeks and measured for DOC (>400 discrete samples). Partial Least Squares Regression (PLSR) was used to predict DOC concentrations from in situ colored-DOM attenuation data to generate a high temporal resolution record of DOC. Results of PLSR’s predictive capability and robustness will be shown for DOC. Predicted DOC can then be fitted to a hydrological model of Groves Creek from which resolved fluxes can address the question of organic carbon outwelling.