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Nitrogen is of great concern to coastal North Carolina: Excess amounts of this nutrient, a byproduct of development, can cause harmful algal blooms and a decrease in water quality. State guidelines and current scientific literature suggest that stormwater ponds permanently remove nitrogen from the environment. Most research guiding stormwater management has taken place in areas other than the coast; guidelines are applied to the coast despite important distinctions in soils and terrain.

Master’s degree student Adam Gold sought to fill a gap in what is known of stormwater ponds by analyzing pond nitrogen removal in coastal North Carolina. Gold’s research took place on Marine Corps Base Camp Lejeune in Jacksonville, as a component of a Defense Coastal/Estuarine Research Program project. He collected sediment cores and water samples from five stormwater ponds encompassing a range of ages. At the UNC Institute of Marine Sciences, his team conducted tests to determine the flux of gases from the sediment surface to assess stormwater pond nitrogen dynamics.

Gold’s study showed that stormwater ponds become less effective at permanently removing nitrogen over time and can become continuous sources of nitrogen during the summer as the ponds age. Results from his research indicate that stormwater ponds can add nitrogen during the summer through sediment nitrogen fixation. Additionally, Gold found that the landscape-wide implementation of stormwater ponds in a coastal residential neighborhood was unable to mitigate the negative effects of development on stream water quality, particularly elevated nitrogen concentrations. His results will inform stormwater management in coastal North Carolina.