title: Temporal variability of combined sewer overflow contaminants: evaluation of wastewater micropollutants as tracers of fecal contamination.
abstract: A monitoring program was initiated for two sewage outfalls (OA and OB) with different land uses (mainly residential versus institutional) over the course of a year. Eleven CSO events resulting from fall and summer precipitations and a mixture of snowmelt and precipitation in late winter and early spring were monitored. Median concentrations measured in CSOs were 1.5 × 10(6)Escherichia coli/100 mL, 136.0 mg/L of Total Suspended Solids (TSS), 4599.0 ng/L of caffeine (CAF), 158.9 ng/L of carbamazepine (CBZ), in outfall OA and 5.1 × 10(4)E. coli/100 mL, 167.0 mg TSS/L, 300.8 ng CAF/L, 4.1 ng CBZ/L, in outfall OB. Concentration dynamics in CSOs were mostly related to the dilution by stormwater and the time of day of the onset of overflows. Snowmelt was identified as a critical period with regards to the protection of drinking water sources given the high contaminant concentrations and long duration of events in addition to a lack of restrictions on overflows during this period. Correlations among measured parameters reflected the origins and transport pathways of the contaminants, with E. coli being correlated with CBZ. TSS were not correlated with E. coli because E. coli was found to be mostly associated with raw sewage whereas TSS were additionally from the resuspension of in-sewer deposits and surface runoff. In receiving waters, E. coli remained the best indicator of fecal contamination in strongly diluted water samples as compared to WWMPs because WWMPs can be diluted to below their detection limits.
authors.affiliation: NSERC Industrial Chair on Drinking Water, École Polytechnique de Montréal, Civil, Geological and Mining Engineering Department, P.O. Box 6079, Station Centre-Ville, Montréal, Québec, Canada. anne.madoux@polymtl.ca
authors.forename: Anne-Sophie
authors.initials: AS
authors.lastname: Madoux-Humery
authors.forename: Sarah
authors.initials: S
authors.lastname: Dorner
authors.forename: Sébastien
authors.initials: S
authors.lastname: Sauvé
authors.forename: Khadija
authors.initials: K
authors.lastname: Aboulfadl
authors.forename: Martine
authors.initials: M
authors.lastname: Galarneau
authors.forename: Pierre
authors.initials: P
authors.lastname: Servais
authors.forename: Michèle
authors.initials: M
authors.lastname: Prévost
mesh_terms: D004926:Escherichia coli; D005243:Feces / Q000382:microbiology*; D057230:Limit of Detection; D011891:Rain; D012212:Rheology; D012499:Sanitation; D012722:Sewage / Q000737:chemistry*; D013997:Time Factors; D062065:Wastewater / Q000737:chemistry*; D014871:Water Microbiology; D014874:Water Pollutants, Chemical / Q000032:analysis*; D014876:Water Pollution / Q000032:analysis*; D018508:Water Purification; D014887:Weather
chemical_list: D012722:Sewage; D062065:Wastewater; D014874:Water Pollutants, Chemical
keywords: Acetaminophen; Caffeine; Carbamazepine; Combined sewer overflows; Escherichia coli; Fecal indicator bacteria; Sanitary sewer