Changements globaux, inondations et terres viticoles : une combinaison à risque pour la qualité des eaux de l’estuaire de la Gironde ?
La fréquence et l’intensité des événements extrêmes, associés à l’élévation du niveau de la mer, prendraient une ampleur sans précédent en raison du changement climatique. Le cumul de ces deux phénomènes provoquerait une augmentation des inondations par crues et submersions marines, notamment sur les zones estuariennes aux interfaces complexes entre terre, mer et fleuve. Le Médoc, sur la rive gauche de l’estuaire de la Gironde, occupé historiquement par des terres viticoles, a subi de graves inondations lors d’événements récents (tempêtes Martin en 1999 et Xynthia en 2010). La remise en eau temporaire de ces terres, fortement contaminées en certains métaux, pourrait avoir des impacts géochimiques sur la qualité des sols et des eaux de l’estuaire. Dans une démarche pluridisciplinaire, associant géochimie, géographie et géomatique, nous proposons d’étudier ces impacts à partir d’une double approche. Après avoir caractérisé les événements météorologiques affectant le Médoc, nous avons déterminé des communes viticoles sensibles aux risques d’inondation à partir de base de données publiques : BD Gaspar sur les arrêtés de catastrophes naturels, BD Agreste pour les surfaces en vigne et BD Primnet pour les zones couvertes par des plans de prévention des risques inondation (approche spatio-statistique). Dans ces communes, nous avons collecté des sols qui ont subi des tests de lixiviation en laboratoire ; les sols ont été mis en contact avec l’eau douce ou estuarienne, afin d’identifier les processus de relargages ou piégeages en métaux et simuler ainsi l’impact des inondations (approche expérimentale). Cette étude s’inscrit dans un programme de recherche pluridisciplinaire Adapt’eau (ANR CEP&S 2011) qui vise à étudier les impacts des changements globaux et à expérimenter des options d’adaptation, notamment la dépoldérisation.
(pp. 1, 09/07/2012)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UR ADBX, IRSTEA
Stratégie bio-analytique de type EDA pour l’identification de contaminants émergents dans les milieux aquatiques : Etude de cas en aval d’un rejet industriel
(04/07/2012)
INERIS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, CNRS
Application de modèles non paramétriques sous R pour l'analyse et le suivi de la qualité de l'eau
Application de modèles non paramétriques sous R pour l'analyse et le suivi de la qualité de l'eau
(02/07/2012)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Les cartes auto-organisatrices de Kohonen appliquées à l'étude des communautés de micro-algues des cours d'eau
Les cartes auto-organisatrices de Kohonen appliquées à l'étude des communautés de micro-algues des cours d'eau
(02/07/2012)
UR REBX, IRSTEA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, INRS - ETE, INRS, PACEA, UB, CNRS
Application de modèles non paramétriques sous R pour l'analyse et le suivi de la qualité de l'eau
Application de modèles non paramétriques sous R pour l'analyse et le suivi de la qualité de l'eau
(02/07/2012)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
On the use of linear stability model to characterize the morphological behaviour of a double bar system. Application to Truc Vert Beach (France).
Sandy barred beaches are often characterized by the presence of rhythmic patterns such as crescentic bars. In this paper, a linear stability analysis (LSA) model is used to characterize the morphological behaviour of the double bar system of Truc Vert beach. Using a limited number of combination of representative bathymetries, wave classes and water levels, the morphodynamic response of the system is analysed, focussing on the geometrical characteristics of 3D patterns generated with the model. These characteristics are described and then compared with available observations. The shapes and the wavelengths of the instabilities predicted by the model compare well with field observations. Thus, the use of linear stability model, with representative hydrodynamic conditions and bathymetries of the considered site, allows a characterization of the global morphodynamic behaviour of a double-barred system.
(Comptes Rendus. Géoscience. vol. 344, n° 1631-0713, pp. 277-287, 28/06/2012)
BRGM, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UPC, UPC
Are antioxidant and transcriptional responses useful for discriminating between chemo- and radiotoxicity of uranium in the crayfish Procambarus clarkii?
The main objectives of this study were to evaluate uranium (U) toxicity in the crayfish Procambarus clarkii at a low dose of exposure and to discriminate between the chemotoxicity and radiotoxicity of U. We conducted two sets of experiments using either 30μgL -1 of depleted uranium (DU) or 233U, which differ from each other only in their specific activity (DU=1.7×10 4Bqg -1, 233U=3.57×10 8Bqg -1). The endpoints were oxidative stress responses and mitochondrial functioning in the gills and hepatopancreas, which were measured in terms of enzyme activities and gene expression levels. U accumulation levels were measured in different organs (gills, hepatopancreas, stomach, intestine, green gland, muscles, and carapace), and internal dose rates in the hepatopancreas were compared after DU and 233U exposures. Significant U accumulation occurred in the organs of P. clarkii, and mitochondrial damage and antioxidant responses were detected. Despite the huge difference (21,000×) in the specific activities of DU and 233U, few significant differences in biological responses were detected in P. clarkii exposed to these two pollutants. This finding indicates that the radiotoxicity was low compared to the chemotoxicity under our exposure conditions. Finally, genes expression levels were more sensitive markers of U toxicity than enzyme activities. © 2012 Elsevier Inc.
(Ecotoxicology and Environmental Safety. vol. 80, n° 0147-6513, pp. 266-272, 01/06/2012)
IRSN/DEI/SECRE/LRE, IRSN/DEI/SECRE, IRSN, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UNIPG, IRSN/DEI/SECRE/LME, IRSN/DEI/SECRE, IRSN
Effects of Methylmercury Contained in a Diet Mimicking the Wayana Amerindians Contamination through Fish Consumption: Mercury Accumulation, Metallothionein Induction, Gene Expression Variations, and Role of the Chemokine CCL2
(International Journal of Molecular Sciences. vol. 13, n° 1661-6596, pp. 7710-7738, 01/06/2012)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, INSERM, CNRS, UPMC, INSERM, CNRS, DC2N, UNIROUEN, NU, INSERM, UPMC, INSERM, IBGC, UB, CNRS
Évènements Rares sur des Séries Temporelles Environnementales
La mesure de l'activité de mollusques bivalves est un moyen d'enregistrer le comportement de bivalves in situ et donc d'évaluer des changements de la qualité de l'eau. Nous proposons une méthode statistique basée sur la théorie des valeurs extrêmes permettant d'estimer des changements globaux (pollution, changement de température) et ainsi d'aider à la surveillance de systèmes aquatiques.
(pp. 1-6, 21/05/2012)
LMBA, UBS, UBO EPE, CNRS, LIMATB, UBS, UBO EPE, IBNM, UBO EPE, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Use of passive samplers extracts for toxicity assessment of environmental realistic mixture of pesticides on natural biofilms communities
The objective of this study was to evaluate the potential use of passive samplers extracts in order to highlight effects of representative pesticide mixtures on natural biofilm communities. Chronic and acute impacts of pesticides in mixture were evaluated using POCIS (Polar Organic Chemical Integrative Sampler) extracts on natural biofilm communities. Biofilms were exposed to POCIS extracts (PE+) or placed in clean water (PE-) in order to maintain or to model a removal of a toxic pressure in relation with a realistic pesticide mixture directly isolated from the field. After 13 days of exposure, a significant decrease of DW, AFDM and diatoms density on downstream biofilms exposed to PE compared to non exposed biofilms was observed; moreover mean chla amount was lower for biofilms exposed to PE compared to non exposed biofilms. Acute toxicity tests at day 13 revealed a significant higher tolerance for PE+ compared to PE- biofilms. Moreover a decrease of tolerance of downstream biofilms from day 0 to day 13 was observed for both treatments; with 51±13 and 43±2% of inhibition at day 13 compared to 25±3% of inhibition at day 0 in the highest concentration (d0). This global decrease of tolerance to PE with time could be explained by differences between channel and field conditions (light intensity, PE composition different from real river exposure due to POCIS selectivity, pesticides concentrations lower in channels than in river,…) Nevertheless, tolerance of downstream biofilms at day 13 still be much more higher than tolerance of biofilms originated from upstream site (significant inhibition of Fv/Fm for d0, d1, d2 and d3 for upstream biofilms). Our results underline impacts of pesticides in mixture on both growth (DW, AFDM and diatoms density) and community tolerance of a natural biofilm. In the one hand, removing the toxic pressure stimulates global biofilm growth but in the other hand it leads to a decrease of biofilms tolerance. A global decrease of tolerance over time for both treatments was observed; nevertheless without reaching the tolerance levels of upstream biofilms. This study highlights the potential use of passive sampler extracts combined with acute toxicity tests in order to evaluate effects of more realistic pesticide mixtures on natural biofilms communities, and then the future and likely applications of such approaches for ecological risk assessment.
(pp. 1, 20/05/2012)
UR REBX, IRSTEA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UR MALY, IRSTEA