title: Multicontamination phenomena occur more often than expected in Mediterranean coastal watercourses: Study case of the Têt River (France).
abstract: Contaminants found in watercourses are not only the result of anthropogenic activities but also depend on river's seasonal hydrodynamics. This is particularly true in Mediterranean climate regions where long dry periods are interrupted by strong rainfalls. Storm events remobilize particles from soils and sediments and, as a consequence, the load of particulate matter in rivers can be quite considerable, severely affecting water quality. Nevertheless, an absence of fieldwork studies exists concerning the simultaneous dynamics of mixtures of pollutants in river waters, particularly during strong rainfalls and floods. Our study assessed the concentrations of six families of pollutants, including pesticides, at these events, and compared them to those observed at drought sampling periods. We have used as model a typical Mediterranean coastal river from Southeast France, the Têt River, whose hydrodynamics and major elements fluxes have been fairly investigated. As expected, our results show that chemical mixtures due to human activities occur and that they are particularly relevant during storm events. But the results of our study argue that exceptional multicontamination phenomena actually happen more often than expected because they are linked to recurrent sudden intense rainfall events in the Mediterranean. In particular, combined sewer overflows are responsible for this major issue in urbanized areas, whereas runoff and leaching will be the most important sources of pollutant mixtures occurring at flood flow peak. After an overview of the sources responsible for chronic multiple stressors events in regions under a Mediterranean climate regime worldwide, we revisit best management measures to reduce risks from the presence of chemical mixtures in the environment.
authors.affiliation: Univ. Perpignan Via Domitia (UPVD), CEFREM, UMR5110, F-66860, Perpignan, France; CNRS, CEFREM, UMR5110, F-66860 Perpignan, France.
authors.forename: Brice
authors.initials: B
authors.lastname: Reoyo-Prats
authors.affiliation: Univ. Perpignan Via Domitia (UPVD), CEFREM, UMR5110, F-66860, Perpignan, France; CNRS, CEFREM, UMR5110, F-66860 Perpignan, France.
authors.forename: Dominique
authors.initials: D
authors.lastname: Aubert
authors.affiliation: Univ. Perpignan Via Domitia (UPVD), CEFREM, UMR5110, F-66860, Perpignan, France; CNRS, CEFREM, UMR5110, F-66860 Perpignan, France.
authors.forename: Christophe
authors.initials: C
authors.lastname: Menniti
authors.affiliation: Univ. Perpignan Via Domitia (UPVD), CEFREM, UMR5110, F-66860, Perpignan, France; CNRS, CEFREM, UMR5110, F-66860 Perpignan, France.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Ludwig
authors.affiliation: Univ. Perpignan Via Domitia (UPVD), CEFREM, UMR5110, F-66860, Perpignan, France; CNRS, CEFREM, UMR5110, F-66860 Perpignan, France.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Sola
authors.affiliation: Sorbonne Universités, UPMC Univ Paris 06, CNRS, UMR7621, Laboratoire d'Océanographie Microbienne (LOMIC), Observatoire Océanologique, F-66650 Banyuls sur Mer, France.
authors.forename: Mireille
authors.initials: M
authors.lastname: Pujo-Pay
authors.affiliation: UPMC Univ. Paris 06, Observatoire Océanologique, F-66650 Banyuls/Mer, France; Sorbonne Universités, UPMC Univ Paris 06, CNRS, UMR7621, Laboratoire d'Océanographie Microbienne (LOMIC), Observatoire Océanologique, F-66650 Banyuls sur Mer, France.
authors.forename: Pascal
authors.initials: P
authors.lastname: Conan
authors.affiliation: Univ. Perpignan Via Domitia (UPVD), CEFREM, UMR5110, F-66860, Perpignan, France; CNRS, CEFREM, UMR5110, F-66860 Perpignan, France; University for Environmental Sciences and Management, North-West University, ZA-2520 Potchefstroom, South Africa.
authors.forename: Olivier
authors.initials: O
authors.lastname: Verneau
authors.affiliation: Univ. Perpignan Via Domitia (UPVD), CEFREM, UMR5110, F-66860, Perpignan, France; CNRS, CEFREM, UMR5110, F-66860 Perpignan, France. Electronic address: carmen.palacios@univ-perp.fr.
authors.forename: Carmen
authors.initials: C
authors.lastname: Palacios
keywords: Mediterranean climate; Multicontamination phenomena; Multiple stressors; Pollutant sources; Storm events; Surface water; Water quality