Wetlands provide landscape-scale reduction in nitrate pollution

  • This research shows that wetland restoration could be one of the most effective methods for comprehensive improvement of water quality in the face of climate change and growing global demand for food.

January 29, 2018 University of Minnesota College of Science and Engineering read full ScienceDaily article here

A new study provides new insights to demonstrate that multiple wetlands or ‘wetland complexes’ within a watershed are extremely effective at reducing harmful nitrate in rivers and streams. These wetlands can be up to five times more efficient per unit area at reducing nitrate than the best land-based nitrogen mitigation strategies

…Significant research findings include:

  • When stream flows are high, wetlands are five times more efficient per unit area at reducing nitrate than the best land-based conservation practices. Other common conservation practices are effective at lower flow conditions but overwhelmed with higher stream flows.
  • The arrangement of wetlands within a watershed is a key predictor of the magnitude of nitrate reduction. If wetlands intercept 100 percent of the drainage area, they are three times more effective at nitrate removal compared to interception of 50 percent of the drainage area.
  • Nitrate reduction due to ephemeral (temporary) wetlands, such as riparian floodplains and more geographically isolated wetlands (wetlands not connected to the river network by surface water), was measurable and was highest during high stream flows, when such features are hydrologically connected to surface water.

….Our work shows that wetland restoration could be one of the most effective methods for comprehensive improvement of water quality in the face of climate change and growing global demand for food,” said study co-author Jacques Finlay, a professor in the University of Minnesota’s Department of Ecology, Evolution and Behavior in the College of Biological Sciences….

Amy T. Hansen, Christine L. Dolph, Efi Foufoula-Georgiou, Jacques C. Finlay. Contribution of wetlands to nitrate removal at the watershed scale. Nature Geoscience, 2018; DOI: 10.1038/s41561-017-0056-6