PhD Dissertation Defense: Adam Gold

The PhD Dissertation Defense of Adam Gold is presented by the University of North Carolina at Chapel Hill’s, Institute of Marine Sciences and the Environment, Ecology and Energy Program. This event will be held on Monday, October 26th at 12:00 pm. This event will be held ONLINE ONLY and it will be available online via Zoom Meeting ID 973 3122 2041

Title: The effects of urbanization on coastal hydrology and biogeochemistry

Abstract: The southeastern United States (US) coastal plain is a unique physiographic region with extensive connections between land and water, and these connections fuel transformations and transport of carbon and nutrients to productive coastal ecosystems. Urbanization, or an increase in the extent of urban area, is occurring rapidly in the southeastern US coastal plain, and although stormwater runoff from urban areas can have negative effects on the ecology of downstream waters, research on this topic in the coastal plain is limited. Engineering approaches characterized as stormwater control measures (SCMs) have been widely implemented in the coastal plain to mitigate negative ecological effects of stormwater runoff without information regarding the long-term impact of SCMs or how they process nutrients. This dissertation characterized the effects of urbanization on coastal plain stream nutrient and carbon export and characterized the efficacy and process-level function of SCMs. Chapter 1 is a review and synthesis that highlights critical gaps related to nitrogen cycling within SCMs. Chapter 2 analyzes flow-through sediment core incubations to measure seasonal nitrogen cycling in coastal stormwater ponds. Chapters 3 and 4 use a years-long streamflow and water quality dataset to analyze the impacts of urbanization on coastal plain stream carbon and nitrogen export. Results from this research show that stormwater ponds often act as temporary sinks for stormwater-derived nutrients or as transformers of nitrogen from inorganic to organic forms, especially during periods of high water temperatures. Results indicated that the volume of stormflow and the amount of nitrogen and carbon exported from coastal streams during storms increased with development. Naturally high concentrations of organic nitrogen and dissolved organic carbon decreased with urbanization, with differences in nitrogen and carbon quality indicating shifts towards more labile anthropogenic sources. This research provides actionable information that managers can use to better mitigate the biogeochemical and ecological effects of urbanization on streams in the southeastern US coastal plain.