Seminar: Christopher Osburn, NCSU Marine, Earth, and Atmospheric Sciences

UNC Marine Sciences’ is proud to host a seminar by Christopher Osburn.

Presenter Affiliation: North Carolina State University (NCSU), Department of Marine, Earth, and Atmospheric Sciences

Title: Scalable Carbon Fluxes across Terrestrial-Aquatic Interfaces of Wetlands and Coastal Waters

Abstract: Carbon and nutrient fluxes across terrestrial-aquatic interfaces (TAIs) are difficult to quantify because of matters of scale: observing, measuring, and modeling processes that occur over millimeters to meters to kilometers, and which vary extensively over time (especially in response to extreme events). The spatial and temporal complexity of TAIs means that they are largely under sampled and hence their coupled biogeochemical cycling remains poorly represented in Earth system models (ESM), generally because processes in these spatially- (and often temporally-) compressed zones usually are inferred rather than directly observed and quantified. One major uncertainty in C flux across the TAI of tidal wetlands is that of dissolved organic carbon (DOC), the most reactive pool of reduced carbon in the ocean. Estimates for the lateral exchange of dissolved organic carbon (DOC) between tidal wetlands and adjacent coastal systems are enormously variable (e.g., ca. 20 to 500 g C/m²yr). DOC export values have often been calculated using measurements made via flume or weirs installed in a tidal creek, with the export estimated by mass balance, resulting in coarse estimates that do not accurately quantify the export across the marsh platform into the main channel of the creek and into adjacent waters. In this talk, I present ongoing we have undertaken to constrain DOC export measurements from a range TAIs in North Carolina and the Gulf of Mexico. Results will be presented from three projects in which various combinations of field observations, ocean-color satellite observations, and the outputs of high-resolution hydrodynamic models were used to estimate DOC export. Further, I will show how geochemical techniques implemented into such flux studies can partition DOC fluxes between upland (terrestrial) and wetland sources.