Combining chemical, bioanalytical and predictive tools to assess persistence, seasonality, and sporadic releases of organic micropollutants within the urban water cycle.

Using a novel liquid chromatography-tandem mass spectrometry method with large volume direct injection and quantitation via isotope dilution, we evaluated the presence of 55 organic micropollutants in wastewater effluents, and locations within the Bow River and Elbow River watersheds in and around the city of Calgary, Alberta, Canada. In addition to establishing baseline micropollutant data for water utility operations, our study aimed to enhance our understanding of micropollutant behavior in the urban water cycle, assess the contributions of three wastewater treatment plants (WWTPs) to downstream receiving waters, explain the potential causes of total estrogenicity measured using the yeast-estrogen screen assay (YES), and prioritize a subset of substances for continuous monitoring. With data spanning 48 months and 95 river km, our results indicate the extensive persistence of metformin (antidiabetic), seasonality of N,N‑diethyl-m-toluamide (DEET, insect repellant), O-desmethylvenlafaxine (antidepressant metabolite), and sulfamethoxazole (antibiotic) in source waters, and sporadic detections of a well-known perfluoroalkyl substance (PFOA).