Residents in rural communities across Canada rely on groundwater as their main drinking water source, but the private maintenance of this source may increase the risk of fecal contamination caused by human or animal wastes. Wainfleet, a rural Ontario community, has been under an active boil water advisory for the past decade. The last study to assess groundwater quality, performed in 2007, determined that half of the 586 groundwater wells contained exceedances in total fecal coliform and E. coli counts. A critical examination of fecal contamination levels and its sources is not only necessary for maintaining public health in the township, but is also an opportunity to examine the robustness of culture-independent methods for quantifying and sourcing fecal contamination in groundwater environments across Canada. For this project, culture-based and culture-independent methods were utilized to quantify and source any fecal contaminants in Wainfleet’s groundwater. Culture counts of fecal indicator bacteria (FIB) suggested that some of the groundwater wells were receiving more fecal contamination than others, as expected based on a previous study that was conducted 10 years prior. The groundwater wells with higher E. coli counts also had higher read counts of microbes like Campylobacterales which could come from septic tanks and higher concentrations of oxidized nitrogen which can also indicate human-based fecal contamination. Finally, fecal contamination in groundwater wells with E. coli tested positive for the human Bacteroidales marker. Taken together, this study shows that fecal contamination pervades groundwater wells across the boil water advisory zone, much of which originates from leaking septic tanks and poorly-constructed groundwater wells. In this study, we have shown that a suite of protocols, from physiochemical quantification to targeted sequencing and qPCR, can be used to complement culture-based assays in quantifying and pinpointing fecal contamination in groundwater sources. / Thesis / Master of Science (MSc) / Boil water advisories are enacted when fecal contamination levels exceed provincial limits. Standard methods for quantifying fecal contamination use the culture-based detection of fecal indicator bacteria. Sequencing the 16S rRNA gene and amplifying Bacteroidales markers can also be used to identify novel fecal markers and quantify host-specific contaminants in source waters. Using culture and genetic-based methods determined that groundwater wells across Wainfleet, a Niagara township with the longest active boil water advisory in Canada, contain septic tank microbes and are primarily contaminated by leaking septic tanks. Genetic-based assays can complement culture-based detection of fecal bacteria in groundwater sources across Canada.
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/20542 |
| Date | 18 November 2016 |
| Creators | Naphtali, Paul |
| Contributors | Schellhorn, Herbert, Biology |
| Source Sets | McMaster University |
| Language | English |
| Detected Language | English |
| Type | Thesis |
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