Stormwater control measures (SCMs) are ubiquitous in urban areas, but the processes that control nitrogen removal within them are understudied. To characterize nitrogen cycling and determine controlling mechanisms in common types of SCMs, this study measured water quality and nitrogen fluxes from the sediments of three stormwater ponds and three stormwater wetlands in the NC Coastal Plain over multiple seasons.
Results/Conclusions
Antecedent temperature was found to be closely related to nitrogen fluxes in both stormwater ponds and wetlands. Higher antecedent temperatures coincided with lower rates of denitrification and higher proportions of temporary nitrate uptake in stormwater ponds, while rates of denitrification in stormwater wetlands increased with higher antecedent temperatures. Water column stratification, nitrate limitation, and low-oxygen conditions in stormwater ponds likely drove pond nitrogen cycling during the summer. These results suggest that higher temperatures associated with seasonality or changes in climate could decrease nitrogen removal by stormwater ponds and increase nitrogen removal by stormwater wetlands.