Investigating the Sources and Transformations of Dissolved Organic Carbon in a Heavily Urbanized Coastal Watershed Following a Hurricane-induced Extreme Flood Event

Abstract:

At the end of August 2017, Hurricane Harvey struck the coast of Texas as a category four storm producing heavy precipitation and massive flooding within the Houston-Galveston watershed. Following the storm, Galveston Bay was converted to a freshwater system, and received 87 Gg of land-derived dissolved organic carbon (DOC) within a week. Sampling was performed after the passing of the storm and continued until the bay returned to normal salinities over 5 weeks. Chemical measurements (DOC, lignin phenols and amino acids) were assessed alongside optical analysis (absorbance and fluorescence) in order to infer the sources and bioreactivity of flood-derived DOC, and the biochemical response of the bay as it returned to the pre-hurricane conditions. As the frequency and intensity of such extreme weather events is expected to increase, the study can be used to build a better predictive framework for the response of the coastal ocean carbon and nutrient budgets, CO₂ flux, and food web dynamics to climate-induced disturbances in the future. An additional goal of the study aimed at calibrating biochemical measurements to absorbance and fluorescence analyses to develop more robust models for DOC cycling in similar coastal ocean environments.