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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.
Beaulieu JJ, Golden HE, Knightes CD, Mayer PM, Kaushal SS, Pennino MJ, et al. (2015) Urban Stream Burial Increases Watershed-Scale Nitrate Export. PLoS ONE 10(7): e0132256. doi:10.1371/journal.pone.0132256
Fresh Water Studies Commons, Terrestrial and Aquatic Ecology Commons, Water Resource Management Commons
This article was originally published Open Access in PLoS One. The full-text article from the publisher can be found here. The work is made available under the Creative Commons CC0 public domain dedication.