Hurricane Harvey's impact on the DOM composition on the south shore of Corpus Christi Bay, Texas

Many studies have assessed changes in dissolved organic matter (DOM) concentrations after storm events, like hurricanes, but overlooked the changes in molecular composition that may be associated with such natural perturbations. Characterization of DOM composition before and after storm events in coastal wetlands and estuaries may provide an improved understanding of processes by which organic compounds are cycled after natural disturbances. The role of DOM in post-storm biogeochemical cycling is increasingly important, especially as the number and strength of named storms continue to intensify with the changing global climate. Water samples were collected from nearshore in Corpus Christi Bay, Texas, two days before Hurricane Harvey made landfall until six months post-hurricane. Here, the PPL-solid phase extraction and direct injection Fusion Orbitrap mass spectrometry, in negative mode, was utilized to molecularly characterize surface water (n=17), shallow groundwater (n=6), and porewater (n=3). Preliminary analyses show an increase in CHO compounds and decrease in nitrogen (N), sulfur (S), and phosphorous (P) containing compounds after storm passage. The study region received the western portion of the hurricane which brought northwesterly winds that caused bay waters to recede from shore. The rampant decrease in surface water level caused a sudden steepening of the hydraulic gradients towards the bay and likely enhanced input of groundwater and flushing of porewater DOM, even though the storm brought trace amounts of precipitation. By six months post-hurricane, and return to natural conditions, the total CHO compounds have decreased while N, S, and P compounds increased to almost pre-storm levels. Return to gentle hydraulic gradients could explain the lower CHO. However, an analysis of the positive mode will be conducted to further characterize trends. Nevertheless, these changes in the DOM chemical composition that are potentially available to the benthic consumers could have large implications on the ecological health of estuaries.