Sources and Transport of Nitrogen in Arid Urban Watersheds

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• 作者：Rebecca L. Hale ; Laura Turnbull ; Stevan Earl ; Nancy Grimm ; Krystin Riha ; Greg Michalski ; Kathleen A. Lohse ; Daniel Childers
• 刊名：Environmental Science & Technology
• 出版年：2014
• 出版时间：June 3, 2014
• 年：2014
• 卷：48
• 期：11
• 页码：6211-6219
• 全文大小：486K
• 年卷期：v.48,no.11(June 3, 2014)
• ISSN：1520-5851

文摘

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^{鈥?/sup>) during storms, and the amount of rainfall N that is retained within urban watersheds. We used triple isotopes of NO₃鈥?/sup> (未15N, 未18O, and 螖17O) to identify sources and transformations of NO₃鈥?/sup> during storms from 10 nested arid urban watersheds that varied in stormwater infrastructure type and drainage area. Stormwater infrastructure and land cover鈥攔etention basins, pipes, and grass cover鈥攄ictated the sourcing of NO₃鈥?/sup> 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.}