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Nitrogen and phosphorus retention in Danish restored wetlands

  • Joachim AudetEmail author
  • Dominik Zak
  • Jørgen Bidstrup
  • Carl Christian Hoffmann
Research Article


Wetland restoration is considered an effective mitigation method for decreasing nitrogen (N) losses from agricultural land. However, when former cropland becomes rewetted, there is a risk that phosphorus (P) accumulated in soils will be released downstream. Here, we evaluate N and P retention in eight restored wetlands in Denmark monitored for 1 year using a mass balance approach. The wetlands represented different types, for instance, lakes and wet meadows, and ages (3–13 years). We also show the results from a long-term monitoring station established in 1973, located downstream a lake that was re-established in 2006. All restored wetlands removed total N (42–305 kg N ha−1 year−1), while some wetlands acted as source of total P and others as a sink (− 2.8 to 10 kg P ha−1 year−1). Our study confirms that restored wetlands are effective at removing N, whereas P can be released for several years after restoration.


Eutrophication Hydraulic residence time Nitrogen Phosphorus Wetland restoration 



We thank Ane Kjeldgaard for her help with GIS, Anne Mette Poulsen for improving the English language and Niels Bering Ovesen and Dorte Nedergaard for quality checking the discharge and nutrient data. We also thank the staff from the Danish Nature Agency and municipalities involved in the monitoring of the restored wetlands. The authors are grateful for the comments received on a previous version of this manuscript by two anonymous reviewers and the editor. This work received funding from the Danish ministry of environment and food.

Supplementary material

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Supplementary material 1 (PDF 2451 kb)


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Copyright information

© Royal Swedish Academy of Sciences 2019

Authors and Affiliations

  1. 1.Department of BioscienceAarhus UniversitySilkeborgDenmark
  2. 2.Naturstyrelsen-HimmerlandSkørpingDenmark

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