5th UF Water Institute Symposium Abstract

Submitter's Name Gurpal Toor
Session Name Sensors and Technologies
Author(s) Gurpal Toor,  University of Florida (Presenting Author)
  Yun-Ya Yang,  University of Florida
  Stefan  Kalev, University of Florida
  Identification of Nitrate-Nitrogen Sources in Residential Stormwater Runoff Using δ15N and δ18O
  Sources of nitrate-nitrogen (NO3-N) in urban residential neighborhood stormwater retention pond waters may include a combination of atmospheric deposition, fertilizers, organic materials, and soil. In this study, we used N and oxygen (O) stable isotopes of nitrate (δ18O-NO3- and δ15N-NO3-) and δ18O and hydrogen (δD) of water (H2O) to identify the dominant sources of NO3-N from a low-density residential neighborhood. Stormwater samples were collected over 25 events during 2014 wet season (July to September) at 5-min intervals using an autosampler installed at the outlet pipe. Isotopic results from δ15N-NO3 and δ18O-NO3 suggest that both atmospheric deposition and chemical fertilizers contributed NO3-N to urban stormwater runoff. The mechanisms driving NO3-N transport during runoff events were primarily hydrologic and not biogeochemical. We suggest that a better understanding of N evolution and sources in residential catchments is important to reduce N loads and improve water quality in urban waters.