The potential for micropollutants and microbial indicators as tracers of domestic sewage contamination along the Bow River
Creators: Hicks, Jaime D
Publisher: name: University of Alberta Library
Year: 2024

<p>Maintaining water quality is essential for overall watershed health. The One Water approach recognizes the interconnectedness of water resources, emphasizing the importance of integrated water resource management. A key threat to water quality is fecal contamination from human and non-human sources. Traditionally, fecal indicator bacteria (FIB) have been used for contamination analysis, but combining FIB with other microbial indicators (e.g., microbial source tracking [MST] markers) and a set of chemical indicators (e.g., micropollutants) offers multiple lines of evidence to assess fecal contamination sources in aquatic environments. The main objective of this thesis was to identify baseline conditions of microbial and chemical indicators at three sites near Calgary along the Bow River (BR): 1) an upstream source water site (BR2), 2) an urban site (BR3), and 3) a site downstream of the City’s three wastewater treatment plants (WWTPs) (BR4). This thesis also developed site-specific fingerprints comprising a set of microbial and chemical indicators that differentiate samples from the three sites. Data processing and visualization of three FIB, 9 MST markers, and 56 chemical indicators collected from 2018 to 2023 were completed using the Python programming language. Parameters with less than seven numerical detections were excluded. Preliminary analysis indicated that the data was mostly non-normal (via the Shapiro-Wilk, D’Agostino’s K2, and Jarque Bera normality tests). Hence the log10 data transformation was used, with the exception of BR2-spring, which utilized the 1/x transformation. The Pearson correlation method was applied to the data in addition to the Ward clustering linkage method. Analysis of the microbial and chemical indicators revealed distinct patterns at the three sample sites. BR4 had the highest diversity of indicators, while BR2 showed minimal impacts. The presence of FIB, MST markers, and chemical indicators at all sites indicates varying levels of human and non-human fecal contamination. Six chemical indicators (caffeine, N,N-diethyl-meta-toluamide [DEET], metformin, O-Desmethyl-venlafaxine [ODV], sucralose, sulfamethoxazole [SMX]) were consistently detected. Total coliforms were positively correlated with the flow at all sites, likely due to increased inputs during high-flow events (i.e., flow enrichment). However, sucralose was found to be inversely correlated with the flow, highlighting dilution effects. Overall, enterococci had higher median concentrations compared to the other FIB, and sucralose dominated the detected chemical indicators across all datasets. The presence of MST markers varied across the sites, with Rum2Bac (ruminant) dominating at BR2, CG01 (Canada goose) at BR3, and HF183 (human) at BR4. Additional relationships were revealed during the correlation and cluster analysis. For instance, at BR2 total coliforms and several chemical indicators (including metformin, ODV, and sucralose) were negatively correlated indicating different sources and/or pathways of entry into BR2. Additionally, the clustering analysis identified three primary clusters: 1) a chemical indicator cluster (ODV, metformin, sucralose), 2) a FIB cluster (E. coli, total coliforms), and 3) a combination of microbial and chemical indicators (caffeine, enterococci, Rum2Bac, DEET, SMX), suggesting potential co-occurrence of these indicators. Increased correlations between E. coli and enterococci as well as between total coliforms and caffeine from BR2 to BR3 were observed. Three of the four main clusters at BR3 contained microbial and chemical indicators, while one cluster was limited to chemical indicators exclusively. Downstream of the WWTPs at BR4, strong positive correlations were seen between E. coli and chemical indicators, while HF183, HumM2 (human), and total coliforms were negatively correlated with various chemical indicators, aligning with previous studies related to wastewater discharges. The diverse array of chemical indicators at BR4 also underscores the cumulative impacts of wastewater discharges at the site. The FIB (E. coli, total coliforms, enterococci), Rum2Bac, metformin, ODV, and sucralose are recommended indicators for site-specific fingerprinting due to their presence at all sites. Additionally, CG01, HF183, HumM2, caffeine, carbamazepine and diclofenac were added to the site-specific fingerprinting recommendations due to their unique presence at BR3 and BR4, indicating that their detection at elevated levels at BR2 can trigger additional source water protection initiatives.</p>