Tracking Nitrogen Sources in Urban Stormwater Runoff from an Urban Residential Neighborhood

Abstract:

The magnitude of nitrogen (N) flux from urban residential neighborhoods to water bodies is not known. We present a case study of N evolution in urban stormwater runoff from a residential neighborhood located in Florida where most runoff is generated by excess rainfall. This rainfall occurs during the 4-month wet season (June-September) that receives ~60 to 70% of 125 cm annual rainfall. The outlet pipe draining the residential neighborhood in Florida was instrumented with ISCO sampler. Stormwater runoff samples were collected every 5-minute following variable storm durations and frequencies during 2014 wet season. Mean concentration of total N in stormwater runoff ranged from 1 to 3 mg L^-1; of which, nitrate-N was <25% and organic N was >60% in most storm events; suggesting different processes controlling N release and transport during variable storm events. Stormwater samples were analyzed for N and oxygen (O) isotopes of nitrate along with hydrogen (H) and O in water to understand the sources of N and water. This presentation will discuss our ongoing research aimed at better understanding the sources, processes, and unraveling the unknowns and uncertainty of N transport from urban coastal systems