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International audience; In France, many rivers face complex cocktails of contaminants at concentrations sometimes close to environmental quality standards (EQS). This type of complex pollution is typically encountered in the case of pesticides, and is usually poorly reflected by the bioindicators currently implemented within the European Water Framework Directive (WFD). In fact these indicators are not always able to reveal the subtle effects of this type of pollution, i.e. direct episodic and chronic or indirect (via trophic transfer, etc.) effects. It is therefore essential to develop indicators able to detect early signs of changes in water quality under natural conditions, but also to assess the possible associated indirect effects (e.g. propagation of effects in the food chain, and from upstream to downstream) and their consequences on the functioning of ecosystems. For this purpose, phototrophic biofilms present a wide range of structural and functional descriptors that could be of interest.The contamination that has been observed for several years in the Cleurie River (Eastern France, Vosges) appears to be an ideal case study site for testing such descriptors. Due to industrial activities (textiles), this small headwater forested stream exhibit a complex cocktail of molecules, chronic and episodic (from daily to seasonal basis) but below EQS. This cocktail is characterized by high concentrations of glyphosate and AMPA as well as a high load of dissolved organic matter (OM) dominated by optical brighteners/dyes. The current media coverage of glyphosate associated to frequent changes in the color of the water feed a local environmental controversy, which is part of the more general and old one on the toxicity of pesticides. In this context, an in situ monitoring, solicited by stakeholders, has been recently initiated in order to identify global indicators allowing studying this contamination. Our objectives are to fingerprint the chemical signature of the toxic pressure (e.g. using integrative passive sampling and spectrometry) and to characterize its effects on biofilms, a pivotal ecological player in these ecosystems. This presentation will focus on the first results: traditional biofilm-based descriptors (primary production, biodiversity) will be compared to others currently under development, either structural (the occurrence of deformities displayed by diatoms) or functional (acquisition of tolerance to glyphosate via a PICT-Pollution Induced Community Tolerance approach). These results will be further used within the framework of a broader interdisciplinary approach aiming at studying the circulation of scientific knowledge between the different actors (researchers, end-users, stakeholders…) involved in this controversy.

International audience

International audience; The AZHUREV surface-flow constructed wetland is a large-scale demonstration wetland built at the outlet of the Grand Reims (France) wastewater treatment plant (WWTP). Three 20,000 m 2 basins (rectangular shape with different depth distribution within each basin) have been created: the initial vegetation (mainly P. australis, S. lacustris and G. maxima) density was also different in each basin. Their aim is to polish a part of the treated wastewater (250 m 3 /h) from the Grand Reims WWTP, as well as to treat part of the Grand Reims stormwater. The basic monitoring of the wetlan is routinely done via sampling at the inlet and the outlet of each basin. However this does not provide information on the spatial distribution of the pollution in the basins, or of temperature and dissolved oxygen. Photographs are routinely taken from the shore but, due to the size of the basins, they do not provide detailed information on the development of the vegetation. To monitor the basins without disturbance, two drones are used:-An aquatic drone (Spyboat by CT2MC) which is remotely driven from the shore. It is fitted with a dissolved oxygen probe and a temperature sensor to collect data 10 cm below the surface. It can also collect liquid samples by means of a peristaltic pump. The superstation in oxygen observed with the aquatic drone in spring is correlated with the increase of the photosynthetically active solar radiation and the development of algae in the basins. Later in the year, anaerobic zones are detected under the duckweed-covered surface. The aquatic drone is more difficult to operate when the duckweed layer is becoming thick or when the surface is frozen.-An aerial drone (type DJI-S900), to better locate dense vegetation beds (especially those of G. maxima) and verify their development. Isolated plants cannot be located easily by the aerial drone. Satellite imaging (Landsat 8 OLI images obtained from https://glovis.usgs.gov) is also tested. The satellites images are collected every two weeks but cannot be used in presence of clouds. In spite of their 30m resolution, they allow to monitor the variation with respect to time of the vegetation, especially the development of duckweed on the wetland surface. The poster will present the latest 2019 results obtained with these tools and discuss further their advantages and disadvantages.

International audience

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International audience; The Azhurev horizontal-flow constructed wetland is a large-scale demonstration wetland built at the outlet of the Grand Reims wastewater treatment plant (WWTP). Three 20,000 m 2 basins (rectangular shape with different depth distribution within each basin) have been created: the initial vegetation (mainly P. australis, S. lacustris and G. maxima) density was also different in each basin. Their aim is to polish a part of the treated wastewater (250 m 3 /h) from the Grand Reims WWTP, as well as to treat part of the Grand Reims stormwater. The wetland has been operated since July 2017. Flowmeters have been installed at the inlet and the outlet of each basin, as well as conductimeters and temperature sensors. Sampling campaigns have been organized on a monthly basis: the samples have been collected at the inlet and exit of each basin as well as in the basins with an aquatic drone. They have been analysed in terms of nitrogen species (total dissolved nitrogen, nitrates, nitrites, ammonia) and dissolved inorganic and organic carbon. The dissolved organic matter has been further characterized by optical methods (synchronous fluorescence and UV-visible spectroscopy). Plants have been collected and their carbon and nitrogen content has been determined. There is no infiltration from the basins to the aquifer, as evidenced by the hydraulic balance. The results obtained after more than one year of operation show a global nitrogen removal rate of 50% (equivalent for nitrates and ammonia). An increase of the dissolved organic carbon has been observed between the inlet and the outlet in summer and fall: this is due to anaerobic decomposition of aquatic plants underneath a thick layer of L. minor, which has gradually covered the basins. In November 2018, a large maintenance of the site has been set up with plant cutting and removal, in order to promote vegetation development in spring. The presentation will describe the complete carbon and nitrogen balance over the two years of operation of the wetland and compare the basin efficiency in function of the vegetation. BIO: N. Maurice is a Ph.D student with a soil and water remediation background.

International audience; The long-term TeaComposition initiative is a worldwide project organized under the umbrella of ILTER to study the decomposition of specific litters (green and red teas) in a large number of sites. The project has raised the interest of the agricultural sector with several questions such as what is the effect of farming practices (tillage, use of natural or chemical fertilizers, etc.) or of the type of crops on litter decomposition. However, for a number of crops (such as cereals, oilseeds, sugar beets), harvesting is done every year and it is not possible to leave the teabags for several years in the soil. The TeaComposition protocole should therefore be adapted for this type of sites. Since 2017, a large-scale experiment has been set up in the Northeast of France. Some 450 (in 2017) to 650 (in 2018) teabags of each type have been buried in different types of soil used for different crops in about 160 parcels. The incubation duration has been limited to three months, in most cases with an implementation between March and May, depending upon the crops. Practical questions such as how to bury efficiently the teabags (i.e. to insure the best contact between teabags and soil), how to weigh them simply in absence of high-precision weighing scale, how to retrieve them easily in the parcel or how to protect them from predators, had to be answered. As litter decomposition is function of soil temperature and humidity, indices has to be defined based on easily obtainable weather data (air temperature, rainfall) at the closest possible weather stations. Finally the change in the nature of the bags (PET instead of nylon) and the possible dependence of the litter decomposition upon the tea harvest year have encourage the accompanying researchers to run specific tests in lab-scale mesocosms and in the field. The presentation will discuss the results obtained with the adapted protocole by the farmers and agricultural institutions and discuss further its advantages and disadvantages.

International audience

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International audience; Dissolved organic matter (DOM) is a significant component of freshwaters affecting biogeochemical cycling of metals and water resource. Various inputs (natural and anthropic) in aquatic ecosystems contribute to the chemical complexity and to the variability in composition and reactivity of dissolved organic matter, including fulvic acids (FA). The aim of this study was to describe at a molecular scale the DOM along the Seine Rivers in order to gain insights into its various origins, and chemical characteristics (compositions, structures and reactivity), by means of complementary approaches using optical method measurements (UV-visible spectroscopy and fluorescence spectroscopy) and ESI-FTMS analysis of FA (electro-spray ionisation Fourier Transform mass spectrometry). Results Surface water samples were collected at different sampling point stations of year 2017 between the source and the estuary. The filtrated samples were directly examined by the aforementioned optical methods. FAs were extracted and purified using OASIS HLB resin. Molecular formula of organic molecules constitutive of FA were extracted from ESI(-)-FTMS data. Aromaticity index calculations led to define three classes of FA molecules, namely condensed aromatics, not condensed aromatics and aliphatic-like compounds. Results were discussed in terms of CHONx (x=S, P, Cl) molecules. Molecular compositions were reported in Van Krevelen (VK) diagrams (H/C atomic ratio vs O/C atomic ratio). Identified molecules (~2470), from a sampling point downstream of Paris, are mainly characterized by O/C ratios lower than 0.7. While nitrogen-containing molecules (80%) are found to be present in the trois classes of compounds, phosphorous (8%) and sulfurous (6%) containing molecules fall only in the aliphatic region of VK diagrams. 'CHONPS' molecules (7%) are poorly-oxygenated (O/C

International audience; Beyond their selective role, some antibiotics continue to exert an effect below their minimum inhibitory concentration level, where they can act as signaling molecules to modulate various bacterial activities: biofilm formation, exopolymers production, virulence, quorum sensing, cell mobility, and even the dissemination of specific antibiotic resistance genes. This clearly asks the question of the possible effects antibiotics can have once diluted after the disposal of reclaimed wastewater into the aquatic environment or during its reuse. Lately we developed a biosensor approach to identify antibiotics interfering with gene regulation. This approach lies on the use of bacteria genetically modified to express a bioluminescence once the promoter of a relevant function is induced by a modulating antibiotic. Rather than testing arbitrary chosen concentrations, the biosensor is exposed to diffusion gradients of antibiotics in agar plate (as for antibiograms) while luminescence profiles are recorded by CCD camera. With such approach we could detect several antibiotics able to trigger the activation of promoters controlling the mobility functions of "integrative and conjugative elements" (ICEs) such as Tn916 and SXT. An automated image analysis algorithm combined with a modelling of the diffusion process in the agar has been developed to convert the luminescence profile into a concentration profile information, enabling to estimate the level of induction and the range of sub-MIC concentration at which an antibiotic remain effective. The biosensor strains are first spread onto the agar of a square Petri dish before receiving one to sixteen antibiotics loaded disks deposited in an equispaced manner. The agar plate is incubated at 30°C allowing the antibiotics to diffuse and luminescence and transmitted light images are regularly acquired over time. An automated image processing system has been developed to detect the induction and inhibition zones around each antibiotic loaded disk. For the present experiment two antibiotics were used: ciprofloxacin (CIP) (broad spectrum) and nalidixic acid (NAL) (limited spectrum). Both inhibit the DNA gyrase while CIP inhibits also topoisomerase IV. Commercially available discs (BioRad) were used (30 µg for NAL and 5 µg for CIP). Additional discs were prepared by loading cellulose discs with antibiotic solutions. The MIC values were determined in separate experiments in liquid phase for each antibiotic. The diffusion of antibiotics in agar is modelled through a finite element computational model based on Fick's second law of diffusion. The simulations are performed using a Computational Fluid Dynamics software (Fluent by ANSYS). The mesh contains ≈ 80,000 cells. It is assumed that the antibiotics deposited in the thin top agar layer exhibit higher diffusivities in this layer than in the bulk solid agar. Bulk agar Top agar The key parameters are the antibiotic diffusivity in the top agar and the diffusivity ratio between the top and the bulk agar. Here D top /D bulk = 1000.  Effect of clone and concentration with NAL  Effect of Petri dish with NAL and CIP (same clone)  Effect of concentration on CIP (same clone) MIC (CIP) = 0.015 µg/mL = 4.5310-5 mole/m 3 MIC (NAL) = 3 µg/mL = 1.2910-2 mole/m 3 D = 1. 10-14 m 2 /s D = 1. 10-11 m 2 /s %of total time D = 1. 10-14 m 2 /s D = 1. 10-13 m 2 /s D = 1. 10-12 m 2 /s D = 1. 10-11 m 2 /s D = 1. 10-10 m 2 /s Range of D for CIP (5 µg) D = 1. 10-10 m 2 /s D = 1. 10-11 m 2 /s D = 1. 10-11 m 2 /s Order of magnitude of D for NAL (30 µg) Simulated MIC paths  The effect of experimental parameters such as clone and antibiotic type and concentration has been tested. An improvement of the spatial resolution would be useful for antibiotics such as NAL with a high MIC.  First simulation results show that it is possible to estimate the diffusivity of an antibiotic in gelose media. A refinement of the simulation mesh is however necessary, especially for high-MIC antibiotics, to estimate properly sub-inhibitory concentrations. Such refinement is currently tested.

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