title: Source tracking of leaky sewers: a novel approach combining fecal indicators in water and sediments.
abstract: In highly urbanized areas, surface water and groundwater are particularly vulnerable to sewer exfiltration. In this study, as an alternative to Microbial Source Tracking (MST) methods, we propose a new method combining microbial and chemical fecal indicators (Escherichia coli (E. coli)) and wastewater micropollutants (WWMPs) analysis both in water and sediment samples and under different meteorological conditions. To illustrate the use of this method, wastewater exfiltration and subsequent infiltration were identified and quantified by a three-year field study in an urban canal. The gradients of concentrations observed suggest that several sources of fecal contamination of varying intensity may be present along the canal, including feces from resident animal populations, contaminated surface run-off along the banks and under bridge crossings, release from contaminated banks, entrainment of contaminated sediments, and most importantly sewage exfiltration. Calculated exfiltration-infiltration volumes varied between 0.6 and 15.7 m(3)/d per kilometer during dry weather, and between 1.1 and 19.5 m(3)/d per kilometer during wet weather. WWMPs were mainly diluted and degraded below detection limits in water. E. coli remains the best exfiltration indicator given a large volume of dilution and a high abundance in the wastewater source. WWMPs are effective for detecting cumulated contamination in sediments from a small volume source and are particularly important because E. coli on its own does not allow source tracking.
authors.affiliation: NSERC Industrial Chair on Drinking Water, Department of Geological, Mining and Civil Engineering, École Polytechnique de Montréal, Montréal, QC, Canada. Electronic address: helene.guerineau@polymtl.ca.
authors.forename: Hélène
authors.initials: H
authors.lastname: Guérineau
authors.affiliation: Canada Research Chair in Source Water Protection, Civil, Geological and Mining Engineering, École Polytechnique de Montréal, Montréal, QC, Canada.
authors.forename: Sarah
authors.initials: S
authors.lastname: Dorner
authors.affiliation: NSERC Industrial Chair on Drinking Water, Department of Geological, Mining and Civil Engineering, École Polytechnique de Montréal, Montréal, QC, Canada.
authors.forename: Annie
authors.initials: A
authors.lastname: Carrière
authors.affiliation: NSERC Industrial Chair on Drinking Water, Department of Geological, Mining and Civil Engineering, École Polytechnique de Montréal, Montréal, QC, Canada.
authors.forename: Natasha
authors.initials: N
authors.lastname: McQuaid
authors.affiliation: Department of Chemistry, Université de Montréal, Montréal, QC, Canada.
authors.forename: Sébastien
authors.initials: S
authors.lastname: Sauvé
authors.affiliation: Department of Chemistry, Université de Montréal, Montréal, QC, Canada.
authors.forename: Khadija
authors.initials: K
authors.lastname: Aboulfadl
authors.affiliation: NSERC Industrial Chair on Drinking Water, Department of Geological, Mining and Civil Engineering, École Polytechnique de Montréal, Montréal, QC, Canada.
authors.forename: Mariam
authors.initials: M
authors.lastname: Hajj-Mohamad
authors.affiliation: NSERC Industrial Chair on Drinking Water, Department of Geological, Mining and Civil Engineering, École Polytechnique de Montréal, Montréal, QC, Canada. Electronic address: michele.prevost@polymtl.ca.
authors.forename: Michèle
authors.initials: M
authors.lastname: Prévost
mesh_terms: D000818:Animals; D002170:Canada; D004784:Environmental Monitoring / Q000379:methods*; D004926:Escherichia coli; D005243:Feces; D005618:Fresh Water / Q000382:microbiology*; D019015:Geologic Sediments / Q000382:microbiology*; D014865:Waste Disposal, Fluid / Q000295:instrumentation* / Q000379:methods; D062065:Wastewater / Q000382:microbiology
chemical_list: D062065:Wastewater
keywords: Escherichia coli; Fecal indicator; Source tracking; Urban canal; Wastewater micropollutants; Water quality