Significance:

Nitrate is the most commonly observed chemical contaminant of ground and surface water in the world. This prevalence leads to nitrate being the major cause for drinking water impairment. Common use pesticides and antibiotics have also become ubiquitous in waterways worldwide, particularly in agricultural settings. While these chemicals are important for agricultural productivity, their release to the environment has resulted in significant impacts to agroecosystem food webs and human health, including bee colony disruptions, human reproductive and development disruption, and the spread of antibiotic resistance. Treatment wetland systems have the potential to be a cost-effective alternative to prevent the release of these chemicals and other emerging contaminants to the environment. However, there is a lack of understanding whether treatment wetlands can remove both nitrate and contaminant mixtures that exist in runoff; a critical knowledge gap that prevents more widespread adoption of this technology.

Objective:

The overarching goal was to improve our understanding of the cumulative effect of increased use and occurrence of commonly detected contaminants of potential concern (CPCs) on nitrogen (N) transformation processes in wetlands.

Hypothesis:

The central hypothesis was that those various mixtures of nutrients and CPCs entering treatment wetlands impact N removal pathways.

Conclusions:

The first study assessed the current state of the literature on the implications to N removal in wetlands in the presence of pesticides and antibiotics. 181 primary studies were identified. Removal efficiencies for nitrate varied widely across the studies, with CPCs impacting microbial communities. A knowledge gap remains in how wetlands are used to treat CPC mixtures resulting in an unknown regarding N removal efficiency.

The second study sought to characterize the CPCs appearing in streams in Kentucky, USA. CPCs were found to vary by location, season, and flood conditions.

The third study researched the impact that Kentucky’s CPCs have on nitrate removal. Two constructed wetland designs, floating treatment wetlands (FTWs), and free-water surface wetlands (FWSs), were evaluated. Nitrate removal was found to be inhibited in the presence of individual contaminants and FWS N removal was significantly impacted by the presence of contaminant mixtures.

The fourth study analyzed the implications of CPC mixtures to N removal by utilizing 15N enrichments to identify specific pathways for nitrate in FWSs and FTWs. While both wetland designs were found to be viable treatment options, differences in management and maintenance plans are needed since the FTWs accumulated more N and CPC in their biomass.

Funded: NSF CAREER and Central Appalachian Regional Education Research Center (CARERC)

Publication:

Nottingham, E. and Messer, T.L. 2021. A literature review of wetland treatment systems used to treat runoff mixtures from urban and agricultural landscapes. Water. 13(2): 3631 doi. 10.3390/w13243631

Nottingham, E., Messer, T.L., Unrine, J., Barton, C., Agouridis, C., and Miller, D.N. The Occurrence and Persistence of Surface Water Contaminants Across Different Landscapes. Science of the Total Environment. https://doi.org/10.1016/j.scitotenv.2024.177837

AEN-178: Wetland Curriculum for Kentucky High Schools

ID-279: Understanding and Protecting Kentucky Wetlands

Graduate Student:
Emily Nottingham (PhD)