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Nitrogen Removal by Stormwater Management Structures: A Data Synthesis
Author(s) -
Koch Benjamin J.,
Febria Catherine M.,
Gevrey Muriel,
Wainger Lisa A.,
Palmer Margaret A.
Publication year - 2014
Publication title -
jawra journal of the american water resources association
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.957
H-Index - 105
eISSN - 1752-1688
pISSN - 1093-474X
DOI - 10.1111/jawr.12223
Subject(s) - stormwater , environmental science , wetland , hydrology (agriculture) , swale , stormwater management , nitrate , nitrogen , ammonium , environmental engineering , surface runoff , ecology , chemistry , biology , geology , geotechnical engineering , organic chemistry
A comprehensive synthesis of data from empirically based published studies and a widely used stormwater best management practice ( BMP ) database were used to assess the variability in nitrogen (N) removal performance of urban stormwater ponds, wetlands, and swales and to identify factors that may explain this variability. While the data suggest that BMP s were generally effective on average, removal efficiencies of ammonium ( NH 4 ), nitrate ( NO 3 ), and total nitrogen ( TN ) were highly variable ranging from negative (i.e., BMP s acting as sources of N) to 100%. For example, removal of NO 3 varied from (median ±1 SD) −15 ± 49% for dry ponds, 32 ± 120% for wet ponds, 58 ± 210% for wetlands, and 37 ± 29% for swales. Across the same BMP types, TN removal was 27 ± 24%, 40 ± 31%, 61 ± 30%, and 50 ± 29%. NH 4 removal was 9 ± 36%, 29 ± 72%, 31 ± 24%, and 45 ± 34%. BMP size, age, and location explained some of the variability. For example, small and shallow ponds and wetlands were more effective than larger, deeper ones in removing N. Despite well‐known intra‐annual variation in N fluxes, most measurements have been made over short time periods using concentrations, not flow‐weighted N fluxes. Urban N export is increasing in some areas as large storms become more frequent. Thus, accounting for the full range of BMP performance under such conditions is crucial. A select number of long‐term flux‐based BMP studies that rigorously measure rainfall, hydrology, and site conditions could improve BMP implementation.