Wetland Flowpaths Mediate Nitrogen and Phosphorus Concentrations across the Upper Mississippi River Basin

Samson G. Mengistu, Heather E. Golden, Charles R. Lane, Jay R. Christensen, Michael L. Wine, Ellen D’Amico, Amy Prues, Scott G. Leibowitz, Jana E. Compton, Marc H. Weber, Ryan A. Hill

Research output: Contribution to journalArticlepeer-review

6 Scopus citations

Abstract

Eutrophication, harmful algal blooms, and human health impacts are critical environmental challenges resulting from excess nitrogen and phosphorus in surface waters. Yet we have limited information regarding how wetland characteristics mediate water quality across watershed scales. We developed a large, novel set of spatial variables characterizing hydrological flowpaths from wetlands to streams, that is, “wetland hydrological transport variables,” to explore how wetlands statistically explain the variability in total nitrogen (TN) and total phosphorus (TP) concentrations across the Upper Mississippi River Basin (UMRB) in the United States. We found that wetland flowpath variables improved landscape-to-aquatic nutrient multilinear regression models (from R2 = 0.89 to 0.91 for TN; R2 = 0.53 to 0.84 for TP) and provided insights into potential processes governing how wetlands influence watershed-scale TN and TP concentrations. Specifically, flowpath variables describing flow-attenuating environments, for example, subsurface transport compared to overland flowpaths, were related to lower TN and TP concentrations. Frequent hydrological connections from wetlands to streams were also linked to low TP concentrations, which likely suggests a nutrient source limitation in some areas of the UMRB. Consideration of wetland flowpaths could inform management and conservation activities designed to reduce nutrient export to downstream waters.

Original languageEnglish
JournalJournal of the American Water Resources Association
DOIs
StateAccepted/In press - 1 Jan 2020
Externally publishedYes

Keywords

  • hydrological connectivity
  • hydrological flowpaths
  • large river basin
  • nitrogen
  • phosphorus
  • watershed
  • wetlands

ASJC Scopus subject areas

  • Ecology
  • Water Science and Technology
  • Earth-Surface Processes

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