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Origin and spatial-temporal distribution of faecal bacteria in a bay of Lake Geneva, Switzerland

Poté, John ; Goldscheider, Nico ; Haller, Laurence ; Zopfi, Jakob ; Khajehnouri, Fereidoun ; Wildi, Walter

In: Environmental Monitoring and Assessment, 2009, vol. 154, no. 1-4, p. 337-348

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    Titre
    • Origin and spatial-temporal distribution of faecal bacteria in a bay of Lake Geneva, Switzerland
    Auteur
    • Poté, John. Forel Institute, University of Geneva, 10 Route de Suisse, P.O. Box 416, 1290, Versoix, Switzerland
    • Goldscheider, Nico. Centre of Hydrogeology, University of Neuchâtel, Rue Emile-Argand 11, 2009, Neuchâtel, Switzerland
    • Haller, Laurence. Forel Institute, University of Geneva, 10 Route de Suisse, P.O. Box 416, 1290, Versoix, Switzerland
    • Zopfi, Jakob. Laboratory of Microbiology, University of Neuchâtel, Rue Emile-Argand 11, 2009, Neuchâtel, Switzerland
    • Khajehnouri, Fereidoun. Laboratory "Eauservice”, Rue de Genève 36, P.O. Box 741, 1002, Lausanne, Switzerland
    • Wildi, Walter. Forel Institute, University of Geneva, 10 Route de Suisse, P.O. Box 416, 1290, Versoix, Switzerland
    Type de document
    • Postprint
    Langue
    • Anglais
    Publié dans
    • Environmental Monitoring and Assessment, 2009, vol. 154, no. 1-4, p. 337-348. Springer Netherlands
    Autre version électronique
    Identifiant OAI-PMH
    • oai:doc.rero.ch:309760
    Summary
    The origin and distribution of microbial contamination in Lake Geneva's most polluted bay were assessed using faecal indicator bacteria (FIB). The lake is used as drinking water, for recreation and fishing. During 1year, water samples were taken at 23 points in the bay and three contamination sources: a wastewater treatment plant (WWTP), a river and a storm water outlet. Analyses included Escherichia coli, enterococci (ENT), total coliforms (TC), and heterotrophic plate counts (HPC). E. coli input flux rates from the WWTP can reach 2.5 × 1010CFU/s; those from the river are one to three orders of magnitude lower. Different pathogenic Salmonella serotypes were identified in water from these sources. FIB levels in the bay are highly variable. Results demonstrate that (1) the WWTP outlet at 30m depth impacts near-surface water quality during holomixis in winter; (2) when the lake is stratified, the effluent water is generally trapped below the thermocline; (3) during major floods, upwelling across the thermocline may occur; (4) the river permanently contributes to contamination, mainly near the river mouth and during floods, when the storm water outlet contributes additionally; (5) the lowest FIB levels in the near-surface water occur during low-flow periods in the bathing season