Sources and transport of nitrogen in arid urban watersheds

Rebecca L. Hale, Laura Turnbull, Stevan Earl, Nancy Grimm, Krystin Riha, Greg Michalski, Kathleen A. Lohse, Daniel Childers

Research output: Contribution to journalArticlepeer-review

65 Scopus citations


Urban watersheds are often sources of nitrogen (N) to downstream systems, contributing to poor water quality. However, it is unknown which components (e.g., land cover and stormwater infrastructure type) of urban watersheds contribute to N export and which may be sites of retention. In this study we investigated which watershed characteristics control N sourcing, biogeochemical processing of nitrate (NO3-) during storms, and the amount of rainfall N that is retained within urban watersheds. We used triple isotopes of NO3-15N, δ18O, and Δ17O) to identify sources and transformations of NO 3- during storms from 10 nested arid urban watersheds that varied in stormwater infrastructure type and drainage area. Stormwater infrastructure and land cover-retention basins, pipes, and grass cover-dictated the sourcing of NO3- in runoff. Urban watersheds were strong sinks or sources of N to stormwater depending on runoff, which in turn was inversely related to retention basin density and positively related to imperviousness and precipitation. Our results suggest that watershed characteristics control the sources and transport of inorganic N in urban stormwater but that retention of inorganic N at the time scale of individual runoff events is controlled by hydrologic, rather than biogeochemical, mechanisms.

Original languageEnglish (US)
Pages (from-to)6211-6219
Number of pages9
JournalEnvironmental Science and Technology
Issue number11
StatePublished - Jun 3 2014

ASJC Scopus subject areas

  • General Chemistry
  • Environmental Chemistry


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