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A Constructed Wetland for Treatment of an Impacted Waterway and the Influence of Native Waterfowl on its Perceived Effectiveness
McMinn, B., S. Klemm, A. Korajkic, M. Herrmann, Rich Haugland, J. Lu, AND E. Villegas. A Constructed Wetland for Treatment of an Impacted Waterway and the Influence of Native Waterfowl on its Perceived Effectiveness. 2018 UNC Water Microbiology Conference, Chapel Hill, North Carolina, May 21 - 24, 2018.
Investigating potential fecal contamination sources at treatment wetland that are resulting in elevated fecal indicator bacterial levels within the treatment system.
The performance of a constructed, variable-flow treatment wetland was evaluated for its ability to reduce bacterial loads from the Banklick Creek, an impacted recreational waterway in Northern Kentucky. Historically, culturable fecal indicator (coliforms and E. coli) bacteria measurements taken at the site revealed little evidence of treatment effect. For this study, levels of traditional (E. coli and enterococci measured by culture and qPCR) and alternative fecal indicators (infectious somatic and F+ coliphage, Clostridium sp. and Clostridium perfringens cultures), pathogens (Campylobacter qPCR) as well as various microbial source tracking (MST) markers (human marker HF183 and avian marker GFD) were monitored through 5 targeted sampling locations within the Banklick Creek Wetland to determine bacterial removal rates for each treatment stage. Sample site #1 corresponds to the creek inflow, site #2 the equalization basin, sites #3 and #4 the upper and lower wetland cell, respectively and site #5 the outlet basin. No difference in concentrations of traditional or alternative fecal indicators were observed in any of the sites monitored. Human marker HF183 concentrations at site #1 were found to be significantly higher (P value range: 0.0016 to 0.0003) than levels determined at sites #3, #4 and #5, and more frequently detected (53% positive samples) than samples taken at later stages of treatment at sites #2 (20% positive samples), site #3 (7% positive samples) and sites #4 and #5 (no positive samples) as well. Conversely, in sites #3 though #5, where bird activity was observed most frequently, the presence of Campylobacter and GFD signals were strongly correlated (P = .0001), while both were found at significantly higher concentrations (P value range: 0.024 to < 0.0001) and more frequently detected (47-93% positive samples) as compared with those measured at sites #1 and #2 (27-33% positive samples). Our study revealed that while the constructed wetland appeared to be effective at removing anthropogenic impacts in the river, bird activities occurring within the wetland negatively impact the overall treatment efficacy.
Record Details:Record Type: DOCUMENT (PRESENTATION/POSTER)
Organization:U.S. ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF RESEARCH AND DEVELOPMENT
NATIONAL EXPOSURE RESEARCH LABORATORY
EXPOSURE METHODS & MEASUREMENT DIVISION
MICROBIAL EXPOSURE BRANCH