Sediment chemistry of urban stormwater ponds and controls on denitrification

Joanna R. Blaszczak, Meredith K. Steele, Brian D. Badgley, Jim B. Heffernan, Sarah E. Hobbie, Jennifer L. Morse, Erin N. Rivers, Sharon J. Hall, Christopher Neill, Diane E. Pataki, Peter M. Groffman, Emily S. Bernhardt

Research output: Contribution to journalArticlepeer-review

8 Scopus citations

Abstract

Stormwater ponds and retention basins are ubiquitous features throughout urban landscapes. These ponds are potentially important control points for nitrogen (N) removal from surface water bodies via denitrification. However, there are possible trade-offs to this water quality benefit if high N and contaminant concentrations in stormwater pond sediments decrease the complete reduction of nitrous oxide (N2O), a potent greenhouse gas, to dinitrogen (N2) during denitrification. This may occur through decreasing the abundance or efficiency of denitrifiers capable of producing the N2O reductase enzyme. We predicted that ponds draining increasingly urbanized landscapes would have higher N and metal concentrations in their sediments, and thereby greater N2O yields. We measured potential denitrification rates, N2O reductase (nosZ) gene frequencies, as well as sediment and porewater chemistry in 64 ponds distributed across eight U.S. cities. We found almost no correlation between the proportion of urban land cover surrounding ponds and the nutrient and contaminant concentrations in the stormwater pond sediments within or across all cities. Regression analysis revealed that the proportion of potential N2 and N2O production that could be explained was under different environmental controls. Our survey raises many new questions about why N fluxes and transformations vary so widely both within and across urban environments, but also allays the concern that elevated metal concentrations in urban stormwater ponds will increase N2O emissions. Urban stormwater ponds are unlikely to be a problematic source of N2O to the atmosphere, no matter their denitrification potential.

Original languageEnglish (US)
Article numbere02318
JournalEcosphere
Volume9
Issue number6
DOIs
StatePublished - Jun 2018

Bibliographical note

Funding Information:
Thank you to Ethan Baruch, Anika Bratt, Dan Dillon, Jacques Finlay, Victoria Green, Jennifer Learned, Tara Trammell, and Megan Wheeler for providing the resources for and/or assistance with field work. Thanks to Brooke Hassett and Brynn O'Donnell for assistance with sample processing at Duke. At Virginia Tech, thanks to Julie Burger, Jinshi Jian, and Lucas Waller for assistance with sample processing and Jefferey Parks for ICP-MS analysis. Thank you to Dean Urban, Marie Simonin, the Bernhardt lab group, and the Duke River Center for helpful feedback on ideas and early drafts of the manuscript. This research was supported by grants from the National Science Foundation's Macrosystems Biology program (NSF EF-1065785) and by the National Science Foundation Graduate Research Fellowship (NSF GDE-1644868). Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Science Foundation.

Funding Information:
Thank you to Ethan Baruch, Anika Bratt, Dan Dil-lon, Jacques Finlay, Victoria Green, Jennifer Learned, Tara Trammell, and Megan Wheeler for providing the resources for and/or assistance with field work. Thanks to Brooke Hassett and Brynn O’Donnell for assistance with sample processing at Duke. At Virginia Tech, thanks to Julie Burger, Jinshi Jian, and Lucas Waller for assistance with sample processing and Jef-ferey Parks for ICP-MS analysis. Thank you to Dean Urban, Marie Simonin, the Bernhardt lab group, and the Duke River Center for helpful feedback on ideas and early drafts of the manuscript. This research was supported by grants from the National Science Foundation’s Macrosystems Biology program (NSF EF-1065785) and by the National Science Foundation Graduate Research Fellowship (NSF GDE-1644868).

Publisher Copyright:
© 2018 The Authors.

Keywords

  • contaminants
  • denitrification
  • metals
  • nitrogen
  • nitrous oxide
  • nitrous oxide reductase
  • stormwater ponds
  • urban biogeochemistry

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