Author ORCID Identifier

https://orcid.org/0000-0002-4781-1236

Date Available

8-20-2024

Year of Publication

2024

Degree Name

Doctor of Philosophy (PhD)

Document Type

Doctoral Dissertation

College

Agriculture, Food and Environment

Department/School/Program

Biosystems and Agricultural Engineering

First Advisor

Dr. Tiffany L. Messer

Abstract

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. The central hypothesis was that those various mixtures of nutrients and CPCs entering treatment wetlands impact N removal pathways. 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. This research helped to reveal the black box of N removal transformations in two constructed wetlands positioned in a variety of landscapes (e.g., urban, rural). Findings were developed into two extension documents included in this dissertation.

Digital Object Identifier (DOI)

https://doi.org/10.13023/etd.2024.277

Funding Information

This project was supported by:

  • UK-CARES Grant P30 ES026529
  • National Science Foundation Grant No. 2042761
  • National Science Foundation Grant No. 1922695.

Its contents are solely the responsibility of the authors and do not necessarily represent the official views of the NIEHS or NSF.

Available for download on Tuesday, August 20, 2024

Share

COinS