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International audience; Four pilot-scale single-stage vertical flow filters (of 2.25 m2 each), treating raw domestic sewage, were studied over 20 months in order to assess the impact of different designs and operational conditions on treatment efficiency. One of them was designed and operated as a standard 1st stage “French” vertical flow constructed wetland unit. The other 3 pilots differed from the standard pilot with respect to the filtration depth, the loading rate or the partial replacement of gravel by zeolite (chabazite), respectively. The pilots were monitored by analysing 24-h flow-weighted composite samples for TSS, CODtot, CODd, ammonium, nitrate and carbonate. All pilots showed a high ability to remove TSS and CODtot, with average removal of 81% and 75%, respectively. Increasing the depth of the filtration layer from 40 to 100 cm allowed to significantly improve ammonium removal (81%), whereas the simultaneous increase in hydraulic and organic loads resulted in a deterioration of ammonium and CODd removals (44% for both parameters). Using zeolite did not induce any observable improvements in ammonium removal under the conditions of the study.

International audience; Grass buffer strips limit the transfer of pesticides from cultivated fields to rivers. These solutions are generally efficient at reducing polluted surface flows, mainly by infiltration of the soil, raising the question of the fate of the infiltrated pollutants. An environmental evaluation was conducted on the efficiency of a grass strip receiving diuron-contaminated water from an uphill vineyard in France. During two runoff events, the following measurements were taken: surface inflow and outflow with Venturi flumes, vertical percolated flow below the root layer (0-50 cm), and variations in water and solute content of the root layer. One runoff event occurred under natural rainfall conditions, while the other runoff event was artificially provoked with water doped by diuron and bromide. For the natural runoff event, representative of medium intensity events, 94% of the diuron was retained in the root layer, whereas 2% left the grass strip by surface runoff and 4% left the grass strip in the water percolating under the root zone. For the artificial event, representative of intense runoff events, more than half of the incoming diuron was retained by the grass strip, whereas 24% and 18% of it were transferred by surface runoff and percolation, respectively. These results showed that the capacity of the root layer to retain diuron was highly significant despite a large percolation flux. However, for large runoff events, surface and subsurface losses can still be considerable, up to 40% of the pesticide load entering the strip.

International audience; An inter-laboratory comparison exercise was organized among European laboratories, under the aegis of EU COST Action 636: "Xenobiotics in Urban Water Cycle" The objective was to evaluate the performance of testing laboratories determining "Endocrine Disrupting Compounds" (EDC) in various aqueous matrices. As the main task three steroid estrogens. 17 alpha-ethinylestradiol, 17 beta-estradiol and estrone were determined in four spiked aqueous matrices' tap water, river water and wastewater treatment plant influent and effluent using GC-MS and LC-MS/MS Results were compared and discussed according to the analytical techniques applied, the accuracy and reproducibility of the analytical methods and the nature of the sample matrices. Overall, the results obtained in this inter-laboratory exercise reveal a high level of competence among the participating laboratories for the detection of steroid estrogens in water samples indicating that GC-MS as well as LC-MS/MS can equally be employed for the analysis of natural and synthetic hormones.

A new relationship between the roughness height and the main hydrodynamic and sediment parameters for plane beds under oscillatory conditions is presented. In order to derive such a relationship, a large data base encompassing plane-bed experiments was compiled from previous investigations and analyzed. Different methods to estimate the roughness height were investigated. Comparisons between the data and different existing predictive formulas for the bed roughness obtained from the literature were also performed. A relationship involving the grain size and Shields parameter only, which is commonly proposed, appeared to be insufficient to characterize the roughness. The roughness height was also found to be a function of the sediment density and the settling velocity. A critical Shields parameter was identified up to which the effective roughness ratio is proportional to the Shields parameter only. The new empirical equation developed in this study provides the highest predictive skill for all conditions investigated.

Anticholinesterase insecticides constitute a major portion of modern synthetic pesticides and the assessment of cholinesterase (ChE) inhibition is widely used as a specific biomarker for evaluating the exposure of non-target organisms to these pollutants. However, most studies on this biomarker were developed on vertebrates and among invertebrates, gastropod mollusks are rarely used. However, gastropods are important members of aquatic habitats and therefore present a high ecological relevance for freshwater ecosystems. In this context, ChE activities were characterized in two freshwater gastropod mollusks, Potamopyrgus antipodarum and Valvata piscinalis, in order to ascertain their value as sentinel species. Firstly, characterization of ChE activities was performed using different substrates (acetylcholine iodide, butyrylcholine iodide and propionylcholine iodide) and specific inhibitors (eserine, iso-OMPA and BW284c51). Secondly, in vivo effect of a widely used organophosphate insecticide, chlorpyrifos, was tested on ChE activity in both species. Results suggested that P. antipodarum possesses two isoforms of cholinesterases, one isoform which properties are intermediate between an acetyl and a propionyl ChE, and one minor isoform which correspond to a butyryl ChE, while V. piscinalis seems to possess only one isoform which displays typical properties of an acetyl ChE. Chlorpyrifos induced no effect on V. piscinalis ChE. In contrast, P. antipodarum activity was significantly decreased by environmental realistic chlorpyrifos concentrations (2.86 and 14.2 nM) after seven days of contact. The present study suggests that P. antipodarum may be employed as a biological indicator for assessing pesticide contamination.

Correspondance: lagache@ensam.inra.fr; International audience; Artificial stream networks play a major role in water and pollutant transfer within cultivated watersheds. Since the characteristics of these artificial stream network (e.g. width, vegetation cover, presence of sediments, etc.) are highly variable in space and in time, describing their variability appears as a prerequisite for assessing environmental risk of pollution at watershed scale. In this perspective an indicator approach is presented which includes three steps: (a) collecting properties of reach (i.e. elementary stream) along an artificial stream networks by means of a field and GIS-based approach, (b) deriving from these properties a set of quantitative indicators of hydrological and chemical processes involved in herbicide transfer, (c) classifying reaches in terms of their role in herbicide transfers on the basis of these indicators. The application of this method to three different watersheds located in France - Roujan watershed (South), La Morcille (East-Centre) and Le Cétrais (North-West) - confirms that artificial stream networks of cultivated watersheds are highly spatially variable in regard to pollutant transfer. This spatial variability includes both variations between the watersheds and variations within the watersheds. Furthermore, the study reveals that the stream network properties can also be variable in time.

Biogeochemical processes mediated by microorganisms in river sediments (hyporheic sediments) play a key role in river metabolism. Because biogeochemical reactions in the hyporheic zone are often limited to the top few decimetres of sediments below the water–sediment interface, slow filtration columns were used in the present study to quantify biogeochemical processes (uptakes of O 2 , DOC, and nitrate) and the associated microbial compartment (biomass, respiratory activity, and hydrolytic activity) at a centimetre scale in heterogeneous (gravel and sand) sediments. The results indicated that slow filtration columns recreated properly the aerobic-anaerobic gradient classically observed in the hyporheic zone. O 2 and NO 3 − consumptions (256±13 μg of O 2 per hour and 14.6±6.1 μg of N–NO 3 − per hour) measured in columns were in the range of values measured in different river sediments. Slow filtration columns also reproduced the high heterogeneity of the hyporheic zone with the presence of anaerobic pockets in sediments where denitrification and fermentation processes occurred. The respiratory and hydrolytic activities of bacteria were strongly linked with the O 2 consumption in the experimental system, highlighting the dominance of aerobic processes in our river sediments. In comparison with these activities, the bacterial biomass (protein content) integrated both aerobic and anaerobic processes and could be used as a global microbial indicator in our system. Finally, slow filtration columns are an appropriate tool to quantify in situ rates of biogeochemical processes and to determine the relationship between the microbial compartment and the physico-chemical environment in coarse river sediments.

International audience; DEBtox model is a biologically based model used to analyse aquatic toxicity data (Kooijman and Bedaux, 1996). To date, it has not been used to analyse sediment survival tests, mainly because this would require daily counting of survivors, which is difficult for benthic organisms. In the present study, we adapted survival toxicity tests with the midge Chironomus riparius to permit survival data analysis with DEBtox. To validate the adaptation proposed, we exposed organisms to two chemicals, copper and methiocarb. We exposed larvae of second, third and fourth instar to different concentrations of the tested compounds and two different diets to assess the influence of diet and instar on DEBtox parameter estimates. Daily counting of organisms did not affect survival and did not lead to much more effort when compared to usual tests. Moreover, the analysis profited much from use of the DEBtox model. It was possible, with only survival data to estimate and validate the kinetics of the compounds, to predict survival during the recovery of exposed organisms and to assess the influence of food availability on toxicity. Food availability did not influence methiocarb toxicity, but copper was more toxic to food-limited organisms when a threshold concentration was exceeded. Comparison of parameters estimate also helped in understanding the differences in toxicity responses between instars. For the two compounds we studied, the difference was entirely explained by differences in threshold values.; Le modèle DEBtox est un modèle à fondement biologique utilisé pour l'analyse des données de toxicité aquatique (Kooijman et Bedaux, 1996). Jusqu'à présent, il n'a jamais été utilisé pour analyser les données des tests de survie sur sédiment, ce qui est principalement du à la difficulté de suivre la survie des organismes benthiques jour après jour. Ici, nous avons adapté les tests de survie avec Chironomus riparius pour permettre l'analyse des données avec DEBTox. Pour valider notre approche, nous avons exposé les organismes à deux contaminants, le cuivre et le mercaptodiméthur (un pesticide). Trois stades larvaires différents (deuxième, troisième et quatrième) et deux régimes alimentaires (ad libitum et limitant) ont été considérés. Le décompte quotidien des survivants n'a pas altéré la bonne marche du test et n'a pas donné lieu à beaucoup plus d'effort qu'un test classique. De plus, nous avons pu tirer des bénéfices de l'utilisation de DEBtox. Il a ainsi été possible, à partir uniquement des données de survie, d'estimer la cinétique des composés, de prédire la survie au cours de la phase de dépuration, et de caractériser l'influence de la nourriture. Le manque de nourriture n'influe pas sur la toxicité du pesticide mais augmente celle du cuivre. Quant à la différence entre stades, elle s'est caractérisée uniquement par une différence entre les concentrations seuils d'effet.

International audience; Pyrene biodegradation in a freshwater sediment without fungi supply, or inoculated with two sediment Micromycetes, Mucor racemosus var. sphaerosporus and Phialophora alba was studied after 0, 5, 13, 28, 60 and 90 days. The influence of glucose addition was estimated, and a liquid chromatographic method for simultaneous quantitative determination of residual anthracene, fluoranthene and pyrene in the sediment was developed. Samples with PAHs were extracted in Soxhlet with ethyl acetate, and LC analysis was performed on a 5µm Supelcosil(TM) column (150×4.6mmI.D.) with gradient elution (2 ml min1) of acetonitrile-water and UV detection at 254 nm. Recoveries of anthracene, fluoranthene and pyrene were 90.3%±1.1%,93.2%±0.9% and 90.42%±1.9%, respectively, without interference. The native sediment microorganisms (with or without glucose added) have shown35% pyrene degradation and sediment with glucose inoculated by the strains revealed 40%.; Etude de la dégradation du pyrène par 2 micromycètes en sédiment d'eau douce.

The GLEAMS model was tested against three observed datasets from different parts of Europe. Three users tested the model independently. Both uncalibrated and calibrated results are presented. The test focused on soil moisture, bromide and pesticide movement. The results show that GLEAMS soil moisture predictions appear to react too rapidly to wet and dry conditions resulting in a rapid change of soil moisture between field capacity and welting point. Incomplete simulation of soil water dynamics seems to be the main reason for underestimation of the tracer movement in soil. In addition, mismatches in soil pesticide concentrations might be partly caused by incorrect prediction of degradation processes in soil. The result of the independent users differed considerably from each other, both in uncalibrated and calibrated results, due to different interpretation of the measured data.; Le modèle GLEAMS a été testé indépendamment par trois utilisateurs différents avec trois bases de données provenant de différentes parties d'Europe. Les résultats avant et après calibration sont présentés. Ils concernent la simulation de l'humidité dans le sol, du transport par infiltration de l'ion bromure et de divers produits phytosanitaires. Les résultats montrent que l'humidité dans le sol simulée par le modèle varie trop brutalement entre la capacité au champ et le point de flétrissement en fonction des apports pluviométriques. Il en résulte une sous-estimation du transport de soluté dans le cas de l'étude. Quant au transport de produits phytosanitaires, l'inadéquation entre les valeurs simulées et observées semble aussi liée à une mauvaise description de la dégradation dans le sol. Enfin, le rôle de l'utilisateur s'est avéré primordial aussi bien pour les essais sans calibration qu'avec calibration.