Sources and Transport of Nitrogen in Arid Urban Watersheds

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...

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Bibliographic Details
Published in:Environmental science & technology 2014-06, Vol.48 (11), p.6211-6219
Main Authors: Hale, Rebecca L, Turnbull, Laura, Earl, Stevan, Grimm, Nancy, Riha, Krystin, Michalski, Greg, Lohse, Kathleen A, Childers, Daniel
Format: Article
Language:English
Subjects:
Applied sciences
Biogeochemistry
Cities
Earth sciences
Earth, ocean, space
Engineering and environment geology. Geothermics
Exact sciences and technology
Hydrology
Infrastructure
Isotopes
Natural water pollution
Nitrates - analysis
Nitrates - chemistry
Nitrogen
Nitrogen Isotopes - analysis
Nitrogen Isotopes - chemistry
Other wastewaters
Pollution
Pollution, environment geology
Rainwaters, run off water and others
Retention
Runoff
Stormwater management
Wastewaters
Water Cycle
Water Pollutants, Chemical - analysis
Water Pollutants, Chemical - chemistry
Water quality
Water treatment and pollution
Watersheds
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Summary: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 – (δ15N, δ18O, and Δ17O) to identify sources and transformations of NO3 – 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.
ISSN:0013-936X
1520-5851
DOI:10.1021/es501039t