title: Urban stormwater runoff nitrogen composition and fate in bioretention systems.
abstract: Multiple chemical forms of nitrogen in urban stormwater make its management challenging. Sixteen storm events were monitored and analyzed for total nitrogen (TN), particulate organic nitrogen (PON), nitrate (NO3-N), nitrite (NO2-N), ammonium (NH3-N), and dissolved organic nitrogen (DON) in stormwater runoff and in treated discharge through a conventional bioretention cell. Influent PON can be effectively removed via bioretention sedimentation/filtration, NH3-N by ion exchange/sorption, and NO2-N by oxidation. However, significant DON and NO3-N leached from the bioretention cell, resulting in only 9% net overall TN concentration reduction. Captured PON and vegetation detritus in the bioretention cell can be leached as DON or mineralized into NO3-N. The effluent N is dominated by NO3-N (46%) and DON (42%). Therefore, in addition to creating denitrification conditions for NO3-N, preventing DON leaching is also critical for effective nitrogen removal though bioretention systems. The bioretention cell exhibited a moderate mass load reduction for TN (41%), which mainly results from runoff volume reduction.
authors.affiliation: School of Environmental Studies, China University of Geosciences , Wuhan, Hubei, 430074, P. R. China.
authors.forename: Liqing
authors.initials: L
authors.lastname: Li
authors.forename: Allen P
authors.initials: AP
authors.lastname: Davis
mesh_terms: D002947:Cities; D058440:Denitrification; D009566:Nitrates / Q000032:analysis*; D009573:Nitrites / Q000032:analysis*; D009584:Nitrogen / Q000032:analysis*; D011891:Rain / Q000737:chemistry*; D058438:Water Cycle; D014874:Water Pollutants, Chemical / Q000032:analysis*; D018508:Water Purification / Q000295:instrumentation* / Q000379:methods*
chemical_list: D009566:Nitrates; D009573:Nitrites; D014874:Water Pollutants, Chemical; D009584:Nitrogen