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ORIGINAL RESEARCH article
Front. Environ. Sci.
Sec. Freshwater Science
Volume 13 - 2025 | doi: 10.3389/fenvs.2025.1513704
This article is part of the Research Topic Nitrate from Field to Stream: Characterization and Mitigation View all 11 articles
Agricultural Nitrate Attenuation in a Small Groundwater-influenced Wetland System
Provisionally accepted- 1 Department of Civil Engineering, University of New Brunswick, Fredericton, Canada
- 2 Canadian Rivers Institute, University of New Brunswick, Fredericton, New Brunswick, Canada
- 3 Fredericton Research and Development Centre, Agriculture and Agri-Food Canada (AAFC), Fredericton, New Brunswick, Canada
- 4 Canada Centre for Inland Waters, Environment and Climate Change Canada, Burlington, Ontario, Canada
Nitrate contamination of freshwater systems is common in agricultural watersheds, leading to human and environmental health concerns. The Bells Creek watershed, located in central Prince Edward Island (PEI), Canada, is dominated by agricultural land use and has elevated nitrate concentrations in groundwater and surface water. Beneficial Management Practices (BMPs), such as constructed wetlands, may provide a means of mitigating such contamination; however, the significance of small wetlands in regulating or attenuating nitrate in PEI has yet to be investigated. In this year-long (August 2023 -July 2024) study, the nitrate loads delivered to a small (1.2 ha) groundwaterinfluenced, stream-wetland system were quantified using high-frequency monitoring techniques. Results indicate that discharge variability is the primary control on the observed variability of surface and subsurface nitrate loads. The total annual nitrate load to the wetland was approximately 30,000 kg NO3-N/yr. Groundwater discharge, which bypasses the wetland riparian zone, contributed approximately 67% of the total load to the wetland. Weekly flux calculations revealed that the wetland behaved as a nitrate sink for 49 out of 52 weeks of the year. Overall, the wetland attenuated 39% of the imported annual nitrate load which, on a wetland catchment area basis, is equivalent to 21.1 kg NO3-N/ha catchment/yr. A positive, non-linear trend between the imported nitrate load and the percent change in nitrate load revealed that the wetland attenuated disproportionately more nitrate during periods of high imported loads. These findings indicate that small, constructed wetlands may be an effective component of BMPs aimed at reducing nitrate loads in agriculturally dominated watersheds like those in Prince Edward Island.
Keywords: Nitrate attenuation, constructed wetland, Agricultural watershed, nitrate load pathways, Beneficial management practices, High-frequency data
Received: 18 Oct 2024; Accepted: 10 Feb 2025.
Copyright: © 2025 Crossley, MacQuarrie and Danielescu. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence:
Kerry T.B. MacQuarrie, Department of Civil Engineering, University of New Brunswick, Fredericton, Canada
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