Nitrogen is the macronutrient limiting primary productivity in coastal waters, such that excess nitrogen can result in coastal eutrophication, harmful algal blooms and dissolved oxygen impairment, both in coastal South Carolina and globally. Nitrogen is also increasingly recognized as the nutrient limiting algal production in freshwater ecosystems, specifically including stormwater ponds. Although ponds are generally effective at retaining and removing most of the phosphorus and other particulate and particle-associated pollutants prior to discharge to receiving waters, they are often much less effective at removing nitrogen and other dissolved pollutants.
Improving nitrogen removal performance in ponds and other SCMs is thus essential for effective water quality management associated with coastal development. In practice, this will depend on the ability to maximize biogeochemical nitrogen removal through improved pond design and retrofits to existing ponds. However, specific mechanisms responsible for net nitrogen removal and the factors that affect their variability within and among various SCMs remains poorly resolved. A comprehensive assessment of nitrogen transformation rates in various types of SCMs represents a critical information need in the application of SCM design recommendations and management practices for promoting effective nitrogen retention for water quality protection in coastal South Carolina.