QUANTIFYING EXCHANGEABLE DISSOLVED ORGANIC CARBON DEPOSITED BY HURRICANE RAINWATER

As hurricane events are expected to intensify in the coming years, it is imperative to understand their capacity for moving organic matter and how they may impact coastal ecosystems. Wet deposition, or precipitation of organic carbon from hurricanes, can transmit massive amounts of marine organic carbon into terrestrial ecosystems in relatively short amounts of time. Some attempts have been made to quantify dissolved organic carbon (DOC) concentrations in hurricane rainwater, but few attempts have been made to calculate exchangeable DOC in rainwater. Exchangeable DOC (EDOC) is defined as the semi-volatile portion of DOC that is available for diffusion across the air-water interface. Consequently, EDOC can significantly affect the carbon cycle. EDOC will be measured using a Shimadzu TOC-VPN analyzer, first without sparging and then with sparging. Hurricane Harvey (August 2017) and Hurricane Florence (September 2018) are two of the wettest storms on record for the United States, delivering approximately 1.3*10¹⁶ liters to areas of the Gulf Coast and 3.8*10¹³ liters of water to the Carolinas, respectively. Preliminary results from Hurricane Harvey rainwater suggest EDOC comprised approximately 19% of total rainwater DOC (0.427 ± 0.005 mg/L). This equates to a total deposition of approximately 5.3*10¹² g of EDOC, which is the same order-of-magnitude of the total annual average rainwater DOC flux globally (430 * 10¹² g C yr-1). These results suggest that EDOC may be a significant and dynamic portion of the global carbon budget that may be influenced by future hurricanes. In this study, levels of EDOC in Hurricanes Harvey and Florence will be quantified and compared to annual loading of total DOC in rainwater.