title: Urban Stream Burial Increases Watershed-Scale Nitrate Export.
abstract: Nitrogen (N) uptake in streams is an important ecosystem service that reduces nutrient loading to downstream ecosystems. Here we synthesize studies that investigated the effects of urban stream burial on N-uptake in two metropolitan areas and use simulation modeling to scale our measurements to the broader watershed scale. We report that nitrate travels on average 18 times farther downstream in buried than in open streams before being removed from the water column, indicating that burial substantially reduces N uptake in streams. Simulation modeling suggests that as burial expands throughout a river network, N uptake rates increase in the remaining open reaches which somewhat offsets reduced N uptake in buried reaches. This is particularly true at low levels of stream burial. At higher levels of stream burial, however, open reaches become rare and cumulative N uptake across all open reaches in the watershed rapidly declines. As a result, watershed-scale N export increases slowly at low levels of stream burial, after which increases in export become more pronounced. Stream burial in the lower, more urbanized portions of the watershed had a greater effect on N export than an equivalent amount of stream burial in the upper watershed. We suggest that stream daylighting (i.e., uncovering buried streams) can increase watershed-scale N retention.
authors.affiliation: US EPA, Office of Research and Development, National Risk Management Research Laboratory, Cincinnati, OH, United States of America.
authors.forename: Jake J
authors.initials: JJ
authors.lastname: Beaulieu
authors.affiliation: US EPA, Office of Research and Development, National Exposure Research Laboratory, Cincinnati, OH, United States of America.
authors.forename: Heather E
authors.initials: HE
authors.lastname: Golden
authors.affiliation: US EPA, Office of Research and Development, National Exposure Research Laboratory, Athens, GA, United States of America.
authors.forename: Christopher D
authors.initials: CD
authors.lastname: Knightes
authors.affiliation: US EPA, Office of Research and Development, National Risk Management Research Laboratory, Ada, OK, United States of America.
authors.forename: Paul M
authors.initials: PM
authors.lastname: Mayer
authors.affiliation: University of Maryland, Department of Geology and Earth Systems Interdisciplinary Center, College Park, MD, United States of America.
authors.forename: Sujay S
authors.initials: SS
authors.lastname: Kaushal
authors.affiliation: University of Maryland, Department of Geology and Earth Systems Interdisciplinary Center, College Park, MD, United States of America.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Pennino
authors.affiliation: Central Washington University, Department of Biological Sciences, Ellensburg, WA, United States of America.
authors.forename: Clay P
authors.initials: CP
authors.lastname: Arango
authors.affiliation: Pegasus Technical Services, Cincinnati, OH, United States of America.
authors.forename: David A
authors.initials: DA
authors.lastname: Balz
authors.affiliation: US EPA, Office of Research and Development, National Health and Environmental Effects Research Laboratory, Duluth, MN, United States of America.
authors.forename: Colleen M
authors.initials: CM
authors.lastname: Elonen
authors.affiliation: US EPA, Office of Research and Development, National Exposure Research Laboratory, Cincinnati, OH, United States of America.
authors.forename: Ken M
authors.initials: KM
authors.lastname: Fritz
authors.affiliation: US EPA, Office of Research and Development, National Health and Environmental Effects Research Laboratory, Duluth, MN, United States of America.
authors.forename: Brian H
authors.initials: BH
authors.lastname: Hill
mesh_terms: D002947:Cities; D017753:Ecosystem; D004784:Environmental Monitoring; D060587:Groundwater / Q000032:analysis*; D006801:Humans; D009584:Nitrogen / Q000032:analysis*; D014481:United States; D014881:Water Supply
chemical_list: D009584:Nitrogen