Contaminant mixtures and their impact on nitrate removal in wetlands: A mesocosm study

Emily N. Byers; Tiffany L. Messer; Daniel N. Miller; Christopher Barton; Jason Unrine; Carmen Agouridis

doi:10.1016/j.jenvman.2025.125518

Contaminant mixtures and their impact on nitrate removal in wetlands: A mesocosm study

Emily N. Byers, Tiffany L. Messer, Daniel N. Miller, Christopher Barton, Jason Unrine, Carmen Agouridis

Research output: Contribution to journal › Article › peer-review

Abstract

Constructed wetlands are used extensively to mitigate surface runoff. While wetland treatment for nitrogen (N) has been comprehensively studied, a knowledge gap remains regarding the implications of other contaminants (e.g., pesticides, pharmaceuticals) on nitrate-N (NO₃-N) removal. This study sought to fill that gap by determining the impact imidacloprid, caffeine, perfluorooctane sulfonic acid (PFOS), atrazine, glyphosate, and sulfate (SO₄²⁻) have on NO₃-N removal rates. The contaminants were determined based on their occurrence across Kentucky surface waters in urban (imidacloprid, caffeine, and PFOS) and rural (atrazine, glyphosate, and SO₄²⁻) environments. Two constructed wetland designs, floating treatment wetlands (FTWs), and free-water surface wetlands (FWSs), were evaluated along with planted and un-planted controls, equating to 24 mesocosms. Individual contaminants in both designs inhibited the rate of NO₃-N removal, while the presence of the contaminants in their mixtures decreased N removal rates in FWSs compared to FTWs. However, by the end of each trial, 72–99 % of the NO₃-N was removed despite the wetland design or the presence of contaminant(s). The FWSs outperformed the FTWs earlier in the growing season (May–June) when the water temperatures were colder, while the FTWs outperformed the FWSs when the plants reached maturity (July–September). Both FTWs and FWSs observed significant removal of contaminants with 28–89 %, 63–70 %, >90 %, and >92 % removal for PFOS, caffeine, glyphosate, and atrazine, respectively. Limited removal of SO₄²⁻ was observed (≤57.9 %). These findings improve our understanding of water treatment for contaminant mixtures and their impact on NO₃-N removal, guiding treatment wetland design and placement.

Original language	English
Article number	125518
Journal	Journal of Environmental Management
Volume	383
DOIs	https://doi.org/10.1016/j.jenvman.2025.125518
State	Published - May 2025

Bibliographical note

Publisher Copyright:
© 2025 The Authors

Funding

This project was supported by a National Science Foundation Grant No. 2042761, National Science Foundation Grant No. 1922695, the U.S. Geological Survey and the Kentucky Water Research Institute under Grant No. G21AP10631, United States Hatch multistate capacity funding grant (W-4045), and UK-CARES P30 ES026529. Its contents are solely the responsibility of the authors and do not necessarily represent the official views of the NSF, USGS, USDA, or NIEHS. Mention of trade names or commercial products in this publication is solely to provide specific information and does not imply recommendation or endorsement by the U.S. Government. The USDA is an equal opportunity provider and employer.The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Emily Nottingham Byers reports financial support was provided by National Science Foundation. Tiffany Messer reports financial support was provided by National Science Foundation. Tiffany Messer reports financial support was provided by United States Hatch multistate capacity funding grant (W-4045). Tiffany Messer reports financial support was provided by University of Kentucky Center for Appalachian Research in Environmental Sciences. Tiffany Messer reports financial support was provided by U.S. Geological Survey and the Kentucky Water Research Institute. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. This project was supported by a National Science Foundation Grant No. 2042761 , National Science Foundation Grant No. 1922695 , the U.S. Geological Survey and the Kentucky Water Research Institute under Grant No. G21AP10631, United States Hatch multistate capacity funding grant (W-4045), and UK-CARES P30 ES026529. Its contents are solely the responsibility of the authors and do not necessarily represent the official views of the NSF, USGS, USDA, or NIEHS. Mention of trade names or commercial products in this publication is solely to provide specific information and does not imply recommendation or endorsement by the U.S. Government. The USDA is an equal opportunity provider and employer.

Funders	Funder number
University of Kentucky Center for Appalachian Research in Environmental Sciences
U.S. Geological Survey
United States Department of Agricultural National Institute of Food and Agriculture Hatch Project
National Institutes of Health/National Institute of Environmental Health Sciences
U.S. Department of Agriculture
Kentucky Water Resources Research Institute	G21AP10631, W-4045
U.S. Department of Energy Chinese Academy of Sciences Guangzhou Municipal Science and Technology Project Oak Ridge National Laboratory Extreme Science and Engineering Discovery Environment National Science Foundation National Energy Research Scientific Computing Center National Natural Science Foundation of China	2042761, 1922695
U.S. Department of Energy Chinese Academy of Sciences Guangzhou Municipal Science and Technology Project Oak Ridge National Laboratory Extreme Science and Engineering Discovery Environment National Science Foundation National Energy Research Scientific Computing Center National Natural Science Foundation of China
UK-CARES	P30 ES026529

Keywords

Denitrification
Floating treatment wetland
Free-water surface wetland
Non-point source pollution
Pesticides
Water quality

ASJC Scopus subject areas

Environmental Engineering
Waste Management and Disposal
Management, Monitoring, Policy and Law

Access to Document

10.1016/j.jenvman.2025.125518

Cite this

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title = "Contaminant mixtures and their impact on nitrate removal in wetlands: A mesocosm study",

abstract = "Constructed wetlands are used extensively to mitigate surface runoff. While wetland treatment for nitrogen (N) has been comprehensively studied, a knowledge gap remains regarding the implications of other contaminants (e.g., pesticides, pharmaceuticals) on nitrate-N (NO3-N) removal. This study sought to fill that gap by determining the impact imidacloprid, caffeine, perfluorooctane sulfonic acid (PFOS), atrazine, glyphosate, and sulfate (SO42−) have on NO3-N removal rates. The contaminants were determined based on their occurrence across Kentucky surface waters in urban (imidacloprid, caffeine, and PFOS) and rural (atrazine, glyphosate, and SO42−) environments. Two constructed wetland designs, floating treatment wetlands (FTWs), and free-water surface wetlands (FWSs), were evaluated along with planted and un-planted controls, equating to 24 mesocosms. Individual contaminants in both designs inhibited the rate of NO3-N removal, while the presence of the contaminants in their mixtures decreased N removal rates in FWSs compared to FTWs. However, by the end of each trial, 72–99 \% of the NO3-N was removed despite the wetland design or the presence of contaminant(s). The FWSs outperformed the FTWs earlier in the growing season (May–June) when the water temperatures were colder, while the FTWs outperformed the FWSs when the plants reached maturity (July–September). Both FTWs and FWSs observed significant removal of contaminants with 28–89 \%, 63–70 \%, >90 \%, and >92 \% removal for PFOS, caffeine, glyphosate, and atrazine, respectively. Limited removal of SO42− was observed (≤57.9 \%). These findings improve our understanding of water treatment for contaminant mixtures and their impact on NO3-N removal, guiding treatment wetland design and placement.",

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author = "Byers, \{Emily N.\} and Messer, \{Tiffany L.\} and Miller, \{Daniel N.\} and Christopher Barton and Jason Unrine and Carmen Agouridis",

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month = may,

doi = "10.1016/j.jenvman.2025.125518",

language = "English",

volume = "383",

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AU - Byers, Emily N.

AU - Messer, Tiffany L.

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AU - Unrine, Jason

AU - Agouridis, Carmen

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N2 - Constructed wetlands are used extensively to mitigate surface runoff. While wetland treatment for nitrogen (N) has been comprehensively studied, a knowledge gap remains regarding the implications of other contaminants (e.g., pesticides, pharmaceuticals) on nitrate-N (NO3-N) removal. This study sought to fill that gap by determining the impact imidacloprid, caffeine, perfluorooctane sulfonic acid (PFOS), atrazine, glyphosate, and sulfate (SO42−) have on NO3-N removal rates. The contaminants were determined based on their occurrence across Kentucky surface waters in urban (imidacloprid, caffeine, and PFOS) and rural (atrazine, glyphosate, and SO42−) environments. Two constructed wetland designs, floating treatment wetlands (FTWs), and free-water surface wetlands (FWSs), were evaluated along with planted and un-planted controls, equating to 24 mesocosms. Individual contaminants in both designs inhibited the rate of NO3-N removal, while the presence of the contaminants in their mixtures decreased N removal rates in FWSs compared to FTWs. However, by the end of each trial, 72–99 % of the NO3-N was removed despite the wetland design or the presence of contaminant(s). The FWSs outperformed the FTWs earlier in the growing season (May–June) when the water temperatures were colder, while the FTWs outperformed the FWSs when the plants reached maturity (July–September). Both FTWs and FWSs observed significant removal of contaminants with 28–89 %, 63–70 %, >90 %, and >92 % removal for PFOS, caffeine, glyphosate, and atrazine, respectively. Limited removal of SO42− was observed (≤57.9 %). These findings improve our understanding of water treatment for contaminant mixtures and their impact on NO3-N removal, guiding treatment wetland design and placement.

AB - Constructed wetlands are used extensively to mitigate surface runoff. While wetland treatment for nitrogen (N) has been comprehensively studied, a knowledge gap remains regarding the implications of other contaminants (e.g., pesticides, pharmaceuticals) on nitrate-N (NO3-N) removal. This study sought to fill that gap by determining the impact imidacloprid, caffeine, perfluorooctane sulfonic acid (PFOS), atrazine, glyphosate, and sulfate (SO42−) have on NO3-N removal rates. The contaminants were determined based on their occurrence across Kentucky surface waters in urban (imidacloprid, caffeine, and PFOS) and rural (atrazine, glyphosate, and SO42−) environments. Two constructed wetland designs, floating treatment wetlands (FTWs), and free-water surface wetlands (FWSs), were evaluated along with planted and un-planted controls, equating to 24 mesocosms. Individual contaminants in both designs inhibited the rate of NO3-N removal, while the presence of the contaminants in their mixtures decreased N removal rates in FWSs compared to FTWs. However, by the end of each trial, 72–99 % of the NO3-N was removed despite the wetland design or the presence of contaminant(s). The FWSs outperformed the FTWs earlier in the growing season (May–June) when the water temperatures were colder, while the FTWs outperformed the FWSs when the plants reached maturity (July–September). Both FTWs and FWSs observed significant removal of contaminants with 28–89 %, 63–70 %, >90 %, and >92 % removal for PFOS, caffeine, glyphosate, and atrazine, respectively. Limited removal of SO42− was observed (≤57.9 %). These findings improve our understanding of water treatment for contaminant mixtures and their impact on NO3-N removal, guiding treatment wetland design and placement.

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KW - Water quality

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Contaminant mixtures and their impact on nitrate removal in wetlands: A mesocosm study

Abstract

Bibliographical note

Funding

Keywords

ASJC Scopus subject areas

Access to Document

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