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International audience; Ce poster présentent les développements réalisés pour la conception de l'application web BUVARD online, destinée au dimensionnement des bandes tampons végétalisées.

National audience; Les contaminants organiques tels que les pesticides et les médicaments présents dans les cours d'eau peuvent se fixer sur les litières de feuilles, les sédiments et les matières en suspension. Ces substances potentiellement toxiques peuvent donc avoir une incidence sur le fonctionnement des écosystèmes lotiques. La détermination des niveaux de contaminations dans ces matrices solides environnementales est donc primordiale pour comprendre et appréhender les effets de ces contaminants dans les milieux aquatiques. Ces analyses de micropolluants à l'état de traces dans de telles matrices constituent un défi de taille, car elles requièrent des techniques analytiques efficaces pour atteindre une sensibilité et une spécificité appropriées. L'extraction et la purification avant analyse chromatographique sont des étapes cruciales qui nécessitent une optimisation afin de maximiser les rendements d'extraction et de minimiser les effets de matrices. En comparaison avec d'autres techniques classiques, la méthode QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe), couramment utilisée pour la sécurité alimentaire depuis 2003, présente l'avantage d'être, simple à mettre en oeuvre, adaptable à tous types de matrices solides, plus respectueuse de l'environnement et permet d'obtenir des extraits relativement propres. L'objectif de cette étude est donc d'optimiser les étapes d'extraction et de purification par QuEChERS. La quantification de 15 pesticides agricoles dans les litières de feuilles et de 49 contaminants d'origine urbaine dans les sédiments est ensuite réalisée par chromatographie liquide ultra haute performance couplée à la spectrométrie de masse en tandem (UHPLC-MS-MS). Le premier groupe de 15 pesticides (2 herbicides et 2 métabolites, 6 fongicides et 5 insecticides) a été sélectionné en fonction de la fréquence de détection de ces composés dans les cours d'eau soumis aux contaminations agricoles diffuses. Le deuxième groupe de 49 substances est représentatif de pollutions urbaines (8 pesticides, 5 bétabloquants, 10 antibiotiques, 4 médicaments hypolipémiants, 2 bronchodilatateurs, 4 benzodiazépines, 2 antidépresseurs, 1 analgésique, 1 diurétique, 1 antidiabétique et 6 métabolites). Ces composés ont été choisis en fonction de leur présence dans les effluents de stations d'épuration. Tous ces composés présentent une large gamme de caractéristiques physico-chimique (-0.5 < log Kow < 5). Afin de sélectionner la méthode d'extraction la plus efficace pour chacun des deux groupes de micropolluants, nous avons tout d'abord comparé la méthode QuEChERS avec une méthode d'extraction liquide sous pression (PLE). Un plan d'expérience a été réalisé pour optimiser la masse et la nature des sels d'extraction et des sels de purification, les temps d'extraction et de centrifugation. Enfin, pour réduire les effets de matrice qui induisent une suppression de signal en UHPLC-MS-MS, des étapes supplémentaires de purification en "Pass through" sur Solid Phase Extraction (SPE) et de dilution des extraits ont été effectuées. Les extractions QuEChERS optimisées couplées à l'analyse par UHPLC-MS-MS permettent d'obtenir des rendements d'extraction compris entre 45 et 135 % en fonction des composés et les écart-types relatifs obtenus sont inférieurs à 20% (n=3). De faibles limites de quantification, allant de 2 ng/g sec à 200 ng/g sec selon le composé et la matrice ont été obtenues. Nous devons maintenant valider et déterminer les incertitudes de ces deux méthodes spécifiques et sensibles avant leur application pour des études de cas réelles.

/ Les bandes tampons végétalisées constituent une solution intéressante pour limiter les transferts de pesticides par ruissellement et réduire la pollution diffuse de l'eau. Pour être pleinement efficaces, elles doivent être adaptées au contexte dans lequel elles sont implantées. BUVARD Online est un outil disponible gratuitement en ligne (https://Buvard.irstea.fr), qui permet de dimensionner des bandes enherbées en tenant compte des conditions locales sur la France métropolitaine.

International audience; Transfer and fate of pesticides are highly influenced by the presence of discontinuities, such as grass strips, ditches, roads, etc. that can accelerate or slow down and dissipate water and contaminant flows. Those landscape features must thus be integrated into watershed management plans. Taking these elements into account in modelling tools is a useful way to evaluate their efficiency on pesticide transfers at the watershed level. However, if processes in landscape features have already been widely modelled locally, models generally don't reach the catchment scale. The PESHMELBA model aims at developping a spatially-explicit modeling tool of water and contaminants circulation and fate at the scale of small catchments in order to optimise the landscape organisation. The model takes into account the spatial organisation of the landscape by representing explicitly the existing features, their location and shape. The final aim of this modelling tool is to compare different scenarios in order to assess the influence of agricultural/landscape management practices on water quality. As a preprocessing step, a meshing representative of the landscape configuration is designed. Instead of being regular as usually done, each mesh unit coincides with one homogeneous landscape element. The final meshing is composed of surface elements (plots, plots with grass strips, grassland, etc.) and linear elements (landscape discontinuities such as ditches, banks or hedgerows, etc.). GeoMELBA, a dedicated tool for landscape discretization was developped to deduce the meshing from different GIS layers provided by the user. Soil types and land uses are overlayed and intersected to deduce surface homogeneous units and linear elements are resliced to fit surface elements boundaries. In addition to shaping the area of application of each modelling unit, this method also aims at defining connectivity between landscape features accordingly to specific flow rules. Dominant processes ruling water and contaminants circulation on each landscape mesh are partly represented by existing and validated models. For example, the Richards equation is solved with the fast solution from \cite{Ross2003} to represent water infiltration, and VFSMOD \cite{Munoz-Carpena1993} is used for grass strips modelling. New modules have also been designed to handle specific elements such as ditches. Each model stands for one or several processes governing water and pesticide transfers and fate in an element. Those modelling units present different levels of complexity in term of representation, from conceptual to physically-based approaches. In order to implement the spatial and temporal couplings, the different modules are connected in OpenPALM, an open-source coupler \cite{Fouilloux1999}. Although this coupler is not hydrology-oriented and doesn't have existing modules for hydrological processes as some existing modelling frameworks, its flexibility and large range of possibilities for coupling models allow to obtain a spatialised model of the whole catchment. In this current phase of construction of the PESHMELBA model, each landscape feature and its dominant processes are integrated one by one and the physical consistency of each module is evaluated. In this study, we will show an application of the PESHMELBA model based on la Fontaine du Theil catchment (France) soil profiles and climatic events. A simplified landscape composed of ditches and plots (fig. \ref{fig:ex}, left) is set up to carry out preliminary tests that aim at assessing the correct functionning of the unitary models and interaction between them. The preprocessing step with GeoMELBA consists in defining the surface and linear elements and assessing the connectivities. Processes that are represented in this example are vertical infiltration, lateral saturated transfers, root extraction, and transformation of pesticides. The first test application simulates water and solute transfers in linears (ditches) and plots on a small virtual catchment with an homogeneous silty-loam soil, after a 8h rainfall event. They highlight two different response speeds for pesticide transfers associated to their pathes: solutes are quickly transferred to outlet by the ditch network whereas transfers are slower along plots. These results show physical consistency and a very good mass balance for water and solutes. As a conclusion, processes still have to be implemented and their evaluation have to be performed, but this method is promising to represent water and pesticides fate in different complex landscapes.

Passive sampling has been developed to obtain, at lower cost, more representative evaluations of the average concentrations of contaminants in aquatic environments. An innovative silicone-based passive sampler (named PACSiR, for Polar Apolar Composite Silicone Rubber) was designed to address sampling, detection and quantification of a wide range of organic contaminants (native or metabolites) present at ultratrace levels in waters. The PACSiR passive samplers, of small size (2 cm length), were applied in different aquatic media (surface or underground waters), typically for periods of 1 week, to evaluate the contamination by a wide range of pesticides and metabolites. They were also tested for their capacity to monitor several hormones and pharmaceuticals. The nature and mass of contaminants sorbed on the passive samplers exposed in situ were used as qualitative or comparative measures, to highlight the presence of compounds or to easily assess trends and gradients of contamination in aquatic environments. For quantitative purposes, the estimation of the average concentration of contaminants in water required the prior determination of kinetic parameters (sampling rate, equilibration time) through laboratory experiments. We demonstrated that this reactive, single-use and low cost passive sampler can be used for multiple research or operational purposes, thanks to the different levels of data acquisition, from qualitative to quantitative approach.

Passive sampling has been developed as an alternative to grab or average automated sampling to obtain, at lower cost, more realistic estimates of the average concentrations of contaminants in aquatic environments. This technique allows the in situ accumulation of chemicals from large amounts of water, resulting in ultratrace level detection and smoothed integrative sampling over exposition periods ranging from days to months. In small agricultural watersheds, pesticide concentrations quickly fluctuate due to episodic rainfall events and resulting transfers from fields to rivers via various pathways (runoff, infiltration, lateral flows...). In this context, an innovative silicone-based passive sampler (named PACSiR, for Polar Apolar Composite Silicone Rubber) was designed to address sampling, detection and quantification of a wide range of organic contaminants (native or metabolites) in waters. The PACSiR passive samplers, of small size (2 cm length), were applied in different aquatic media (surface or underground waters) to estimate the levels of contamination by pesticides of different families. The nature and mass of contaminants sorbed on the passive samplers exposed in the field were used as qualitative or comparative measures, to highlight the presence of compounds or to easily assess trends and gradients of contamination in aquatic environments. For quantitative purposes, the estimation of the average concentration of contaminants in water required the prior determination of kinetic parameters (sampling rate, equilibration time) through laboratory experiments. In this study, PACSiR passive samplers were deployed in situ, typically for periods of 1 week, to evaluate the contamination of agricultural watercourses by a wide range of pesticides and metabolites under different agro-pedo-climatic conditions. These small tools were also successfully used to assess the variation of pesticide concentrations in time and space in subsurface waters thanks to the use of piezometers. In typical small agricultural watersheds, comparative studies between upstream and downstream sites allowed to highlight clear gradients of contamination in rivers and to put forward the role of wetland buffer zones. Finally, we could determine average concentrations with their associated uncertainties for about 30 pesticides and metabolites that were previously calibrated in laboratory. The values achieved with this new passive sampler were in accordance with average concentrations obtained with active grab or automated sampling techniques. We demonstrated that this reactive, single-use and low cost passive sampler can be used for multiple research or operational purposes, thanks to the different levels of data acquisition, from qualitative to quantitative approach.

/ Située sur l'Aire d'Alimentation de Captage (AAC) de Villevieux (eau potable de la ville de Lons-le-Saunier, Jura), la Madeleine est une rivière fortement exposée aux pesticides agricoles provenant de cultures diverses (céréales, maïs, colza, vigne). Le service des eaux, gestionnaire de l'AAC, a mis en place entre 2011 et 2016 un suivi de la qualité chimique des eaux des rivières du captage par prélèvements ponctuels, qui a notamment soulevé des interrogations sur la contamination des eaux dès les sections amont de ces rivières, et sur la contribution des différents affluents. Néanmoins, un diagnostic précis de la contamination en pesticides est difficile à réaliser à cause du manque de représentativité temporelle des prélèvements ponctuels réalisés, et devant l'absence de prise en compte de la toxicité potentielle associée. C'est ainsi qu'au printemps et à l'automne 2017, périodes propices aux transferts de pesticides vers les cours d'eau, des outils de diagnostic de la qualité chimique et biologique ont été déployés pendant un mois sur 3 stations de la Madeleine de façon à intégrer les apports à la contamination de deux principaux affluents. En plus de la variabilité saisonnière, une variabilité temporelle plus fine a été évaluée par le déploiement de certains outils sous forme de séquences de plusieurs tests (séquences d'un mois constituées de 4 ou 2 tests de 7 ou 15 jours respectivement). Le diagnostic a été réalisé à l'aide : i) d'échantillonneurs passifs (Tige Silicone Polaire et POCIS permettant l'analyse de 70 substances actives ou métabolites de pesticides) : placés dans le cours d'eau, ils permettent un échantillonnage en continu, et améliorent ainsi la représentativité de la mesure de la qualité du milieu par l'obtention d'une concentration intégrée sur le temps d'exposition de l'outil (7 ou 14 jours). ii) de la bioviosurveillance active qui permet de mesurer des effets toxiques aux échelles moléculaires et individuelles chez des organismes Gammarus fossarum transplantés (encagements). Les marqueurs choisis ont été la survie, l'inhibition de l'activité acétylcholinestérase, le taux d'alimentation et les marqueurs de reproduction. Nous présenterons dans ce poster les premiers résultats de ces expérimentations complémentaires qui mettent en évidence des variabilités spatiales et temporelles (hebdomadaires et saisonnières) de la contamination en pesticides et de l'impact toxique, et permettent ainsi de compléter le diagnostic de la qualité de l'eau de la Madeleine.

International audience; In the context of the European Water Framework Directive (WFD, 2000/60/EC), which aims to achieve a good ecological and chemical status for all natural aquatic environments, it is necessary to better quantifying pesticide transfers in agricultural watersheds. Modeling is a relevant tool to study the processes occuring in the fate of pesticides, and identifying sound managing solutions to water contamination. Physically-based and spatially distributed models are particularly useful to represent in detail processes and interactions between the soil surface and subsurface. In particular, they can help to assess the role of landscape elements such as vegetative buffer strips, ditches, ... . The present study aims to test a recently added reactive transport to the coupled surface water/groundwater 3D model CATHY, in order to represent pesticide transfers at the watershed scale. Contaminant reactions implemented are linear adsorption and degradation (first order kinetics). The model has been successfully validated on laboratory data and submitted to a sensitivity analysis as a further step of validation. In this study, we tested the model on field conditions, simulating a 150 m x 40 m hillslope in the Morcille catchment (Beaujolais, France). The hillslope is predominantly covered with a chemically weeded vineyard crossed by 4 very shallow ditches gathering the runoff towards a concrete channel. The flow coming from the vineyard plot in then conducted on a 25 m long vegetative buffer strip. The site is instrumented with piezometers, lysimeters, flow and solute concentration measurement devices. Real field conditions makes the model's application more difficult because of the complexity in representing the interactive processes in a large domain, combined to uncertainty on input parameters that is important in field experiments. However, such challenging modeling allows a more comprehensive understanding of solute transfers and gives some keys to evaluate the efficiency of mitigation elements of the landscape.

International audience; Several types of passive samplers have been developed for the time-integrative monitoring of various organic contaminants in the aquatic environment. The passive SBSE (p-SBSE) has been recently demonstrated to be a suitable passive sampler for pesticides monitoring in agricultural watersheds. Nevertheless, for the determination of time-weighted average (TWA) concentrations, a calibration of the passive samplers under controlled conditions has to be performed prior to field exposure in order to determine for each pesticides accumulation kinetics and sampling rates (Rs). Many calibration systems have been described in the literature, but we could not find any comparison of these experimental systems for a same passive sampler and tested compounds. The aim of this study was to test two different laboratory experimental systems (continuous flow and static mode) for the calibration of p-SBSE for 16 pesticides with a wide range of physico-chemical properties (log Kow 2.2 – 5.1). We evaluated the performances of both systems in terms of consumption of water and pesticides, and stability of flow rate, temperature and pesticides concentration during the calibration experiments. The continuous flow calibration was performed in 15 glass channels (3 L each and a triplicate of p-SBSE per channel) and was based on a constant supply of water contaminated with the studied pesticides. The nominal concentrations ranged from 0.2 to 40 µg/L depending on the pesticides. The static mode calibration consisted in placing the passive samplers (up to 24 p-SBSE) in a 30 L-stainless steel tank containing spiked silicone sheets (8 sheets used), as a diffuse source of pesticides in order to generate a constant water contamination during the calibration period. The nominal concentrations of pesticides ranged from 0.1 to 150 µg/L. We performed the calibration at 20°C during 7 days for both experimental systems. The flow velocity was 2.5 cm.s-1 in the continuous flow calibration, and 10 cm.s-1 in the static mode calibration. For both systems, the temperature and the water flow velocity were stable during the calibration (20°C ± 1 for temperature, and RSD lower than 14% (n=240) for flow velocity measurements). The main advantage of the continuous flow calibration system is that the hydrodynamic conditions are close to the in situ conditions. However, it requires huge volumes of water (2000 L) and a large amount of pesticides (3.5 g) for spiked water renewal in order to maintain hydrophobic pesticide concentrations stable. Moreover, the system is relatively complex to operate due to the large number of pumps that need to be accurately calibrated. On the contrary, the static mode calibration system allows a limited consumption of water (30 L) and pesticides (0.1 g) as water renewal was not needed. This system is easy to use and stable contaminant concentrations in water can simply be maintained. However, it requires a previous step for spiking the silicone sheets which implies to know the exchange kinetics between silicone sheet, water and passive samplers before calibration. Both systems enabled to obtain curvilinear sorption profiles for 16 pesticides that were used for the determination of Rs. For hydrophilic compounds, the calculated Rs are similar with both systems, whereas for hydrophobic pesticides, the Rs obtained with the batch mode calibration system are generally greater, which can be relied to the difference of flow velocity between the two systems.

International audience; The modeling toolkit BUVARD (BUffer strip for runoff Attenuation and pesticides Retention Design tool) consists in several steps like analyzing the watershed and its characteristics (soil, climate, cultural practices), and running dynamical models, in particular the mechanistic model VFSMOD. At the end this toolkit delivers the optimal VFS width considering the needed filter efficiency (for example, 70% of runoff reduction).The present study aims at making possible to simplify this very complete method, to determine its sensitivity to input parameters in new climatic and agronomic conditions by reducing the computational cost of the modeling toolkit. A metamodel (or surrogate model) developed on local conditions would allow to perform GSA with low cost yet ensuring it is based on physics. It would help users understanding the most important processes in the VFS they want to design and would increase the operational scope of the modeling toolkit. We performed a much smaller sampling of input parameters using the Latin Hypercube Sampling method optimized with a maximin criteria. The metamodel is then be based on a Kriging approach with a very good quality of prediction. It is a promising tool to perform uncertainty analysis and sensitivity analysis at alow cost.

[Departement_IRSTEA]Eaux [TR1_IRSTEA]ARCEAU; International audience; Physically-based models represent detailed surface/subsurface transfer, but the required spatial information does not allow their operational use. In situ data on pesticides in a catchment are usually rare and not continuous in time and space. Satellite images, on the other hand, well describe data in space, but only water related, and at limited time frequency. This study aims to exploit these 3 types of information (model,in situ data, images) with data assimilation methods adapted to image data, in order to improve pesticide and hydrological parameters and better understand physical processes. This poster discusses the proposed methodology as well as the available study site data and modeling components.

International audience; During the last decade, the interest on the fate of emerging organic micropollutants, including pharmaceuticals and pesticides, in rivers and waste waters has constantly grown. Analysis of these pollutants at trace level in complex matrices is an analytical challenge that requires the development of reliable analytical methods. Based on the conclusions of national research programs on wastewater and sludge treatments and on expert opinions, indicative compounds typical of urban domestic pollution were selected according to i) their frequency of quantification in untreated wastewaters, secondary and tertiary wastewater effluents and in receiving rivers, ii) their toxic effect in aquatic and terrestrial ecosystems, iii) their large range of physico-chemical properties (log Kow, pKa) and chemical classes. Finally, 49 targeted compounds were selected, including 8 pesticides, 35 pharmaceuticals compounds (antibiotics, antidepressants, betablockers, anti-inflammatories, hypolipemiants and anticarcinogens) and 6 metabolites, to be part of a multiresidue method. This method also includes 4 priority substances (simazine, atrazine, diuron and isoproturon) of the Water Framework Directive (WFD, 2000/60/CE) and one watch-list substance (diclofenac) of the WFD daughter directive (2013/39/UE). After collection in field, water samples were filtered and acidified. Samples were concentrated and purified by solid phase extraction (SPE). Twenty-two stable isotope labelled compounds were used as surrogates to overcome matrix effects generated during whole analytical procedure. Ultra high performance liquid chromatography (UHPLC) coupled to electrospray (both positive and negative ionization) tandem mass spectrometry was performed in the multiple reaction monitoring (MRM) mode, so molecule identity could be confirmed by two quantitation and confirmation transitions according to the EC Commission Decision (2002/657/CE), except for diclofenac. We present accuracy, linearity and limits of quantification (LOQ) in intermediate fidelity conditions (intra-laboratory reproducibility), evaluated in real waters. As examples of application, we present concentration ranges for these compounds measured in rivers and wastewaters.

International audience; Grab sampling may be scarcely adequate to evaluate the impact on surface waters of pesticide used in agriculture because of its poor spatiotemporal representativeness compared to the high variability of the contamination patterns. Indeed, it is still not easy to link the effect of agricultural practice changes to water quality at the catchment scale. Furthermore, biological indicators may also be useful in addition to pesticide concentration determination to evaluate their impact on ecosystems. In this way, the contribution of new integrative tools has been evaluated. Passive samplers and biological indicators have been applied together at the catchment scale so as to identify their coherence and complementarity. The tested chemical tools are the passive-SBSE (Stir Bar Sorptive Extraction) dedicated to hydrophobic to moderately hydrophilic compounds and the POCIS (Polar Organic Chemical Integrative Sampler) dedicated to hydrophilic compounds. As concerns biological approach, it consisted in the in situ deployment of i) caging methodology with a highly ecological relevant amphipod species, Gammarus fossarum, coupled to the measurement of toxicity markers (acetylcholine esterase inhibition, feeding rate) and ii) the study of microbial and macro-invertebrate communities (measurement of leaf decomposition rates) as well as phototrophic periphytic communities (measurement of Pollution Induced Community Tolerance). These tools have been applied during june 2014 (corresponding to vineyard and corn period of application) in two contrasted agricultural catchments. The Ardières basin situated in the Beaujolais region (France) is submitted to viticulture pressure and a marked pesticide contamination has already been highlighted. Three measurement stations have been chosen so as to search for a contamination gradient from upstream to downstream. The Coise basin is located in the Monts du Lyonnais (France) in a zone of mixed farming breeding with a predominance of meadows, corn and cereals. Three measurement stations have been selected on three sub-catchments corresponding to differentiated pesticide use. In total, 49 pesticides (28 herbicides, 9 fungicides and 12 insecticides) have been analyzed as well as potential confusing parameters (metal(oïd)s, nutrients, temperature, luminosity, water flow). Results show the high coherence of chemical and biological tools responses. All of them were able to reflect the spatial contamination gradients as well as the specific contamination and impact associated to each agro-pedo-climatical context. A weekly exposure also permitted to take into account the temporal variability of the contamination according to flood occurrence. Finally, their sensitivity, reactivity and integration capacity make these tools relevant and promising to assess agricultural pesticide impact on surface water in addition to grab sampling.

International audience; The use of pesticides in agricultural fields leads to nonpoint source contamination of freshwaters by various pathways (runoff, infiltration, lateral flows…). Different research programs have been developed to study and explain these transfer mechanisms. They required specific sampling strategies for each compartment of the aquatic environments. Passive sampling has been introduced as an alternative to grab or average automated sampling, in order to obtain at lower cost, more realistic estimates of the contamination levels of pesticides in water. This technique allows the in situ accumulation of chemicals over exposition periods ranging from days to months. Silicone rods, investigated in this work, are single-use and low cost new passive samplers. Extraction and quantification of pesticides from silicone rods were performed by liquid desorption followed by UHPLC-MS/MS. The nature and mass of pesticides sorbed on in situ exposed silicone rods can be used as qualitative and semi-quantitative measures to assess trends or gradients of contamination at different scales: from plots to rivers or watersheds. The aim of this study was to investigate the use of silicone rods as a passive sampling technique in different water bodies and to assess their benefits for the monitoring of pesticides and metabolites with various physico-chemical properties. Firstly, silicone rods have been exposed during one month (four exposition periods of one week) in a river located in a vineyard watershed with a marked pesticide contamination. Fifteen pesticides, mainly fungicides, were sorbed on silicone rods, but also insecticides that could not be detected in parallel grab samples. A strong gradient of contamination was clearly shown according to the increase of land use. Contamination reaches a maximum in the second week corresponding to a rainy period after a dry one. A second application of silicone rods consisted in their deployment inside a network of piezometers in an instrumented vineyard plot to evaluate the spatial propagation of pesticide contamination during a rainfall event. Silicone rods allowed for the qualitative detection of seventeen pesticides from different families and origins. The spatial dispersion of pesticides highlighted a strong axial subsurface transfer following the slope of the plot. The comparison of upslope and downslope masses of pesticides sorbed on the rods permitted to discriminate the behaviour of the pesticides either in controlled conditions (for pesticides injected during a simulation event) or in natural conditions (for pesticides applied on the plot by the farmer). We illustrated here that sensitive passive samplers can now be considered as an alternative or complement to grab sampling to improve the monitoring of pesticides in aquatic environments by integrating pesticide concentration variations over exposition periods.

International audience; In Europe, a significant presence of contaminants is found in surface water, partly due to pesticide applications. Vegetative filter strips or buffer zones (VFS), often located along rivers, are a common best management practice (BMP) to reduce non point source pollution of water by reducing surface runoff. However, they need to be adapted to the agro ecological and climatic conditions, both in terms of position and size, in order to be efficient. The TOPPS-PROWADIS project involves European experts and stakeholders to develop and recommend BMPs to reduce pesticide transfer by drift or runoff in several European countries. In this context, Irstea developed a guide accompanying the use of different tools, which allows designing site-specific VFS by simulating their efficiency to limit transfers using the mechanistic model VFSMOD. This method which is very complete assumes that the user provides detailed field knowledge and data, which are not always easily available. The aim of this study is to assist the buffer sizing by using a unique tool with a reduced set of parameters, adapted to the available information from the end-users. In order to fill in the lack of real data in many practical applications, a set of virtual scenarios was selected to encompass a large range of agro-pedo-climatic conditions in Europe, considering both the upslope agricultural field and the VFS characteristics. As a first step first, in this work we present scenarios based on North of France climate consisting of different rainfall intensities and durations, hillslope lengths and slopes, humidity conditions, a large set of field rainfall/runoff characteristics for the contributing area, and several shallow water table depths and soil types for the VFS. The sizing method based on the mechanistic model VFSMOD was applied for all these scenarios, and a global sensitivity analysis (GSA) of the VFS optimal length was performed for all the input parameters in order to understand their influence and interactions, and set priorities for data collecting and management. Based on GSA results, we compared several mathematical methods to compute the metamodel, and then validated it on an agricultural watershed with real data in the North-West of France . The analysis procedure allows for a robust and validated metamodel, before extending it on other climatic conditions and typical european watersheds . The tool will allow comparison of field scenarios, and to validate/improve actual existing placements and VFS sizing

International audience; The implementation of the WFD (Water Framework Directive), requests European Union member states to achieve good qualitative and quantitative status of all water bodies in 2015. The monitoring of organic micropollutants such as pesticides is an essential step to assess the chemical and biological state of streams, to understand the reasons of degradation and to implement sound mitigation solutions in the watershed. In particular, the water sampling, which can be performed according to several strategies, has to be closely adapted to the experimental goals. In this study, we present and compare 3 different active sampling strategies: grab sampling, time-related and flow-dependent automatic samplings. In addition, the last two can be fractionated (i.e. several samples collected, and each one contained in a single bottle) or averaged (i.e. several samples mixed in the same bottle). Time-related samples allow the assessment of average exposure concentrations of organic micropollutants, whereas flow-dependent samples lead to average flux concentrations. The 3 sampling strategies were applied and compared during the monitoring of the pesticide contamination of a river located in a French vineyard watershed (the Morcille River, located 60 km north of Lyon, in the Beaujolais region). Data were collected between 2007 and 2011, during different seasons and for a range of hydrological events. The Morcille watershed is characterized by contrasted hydrological events with a very short-time response due to its small size (5 km2), steep slopes (20 to 28%) and highly permeable sandy soils. These features make it particularly difficult to monitor water quality, due to fast variations of pesticide concentrations depending on rain events. This comparative study is performed in 2 steps. At first, we compare the timestamps of each sample composing the weekly-averaged samples and those of the grab samples with hydrological data. This allows us to evaluate the efficiency of these 2 sampling strategies in the integration of flow variations and therefore pesticide concentration variations during the sampling campaign. In a second step, we use the fractionated samples data during flood events to calculate the concentrations of virtual averaged samples of the events. Different time or flow steps were used for the calculation, to assess their impact on the pesticide averaged-concentrations or fluxes. These analyses highlight the benefits and drawbacks of each sampling strategy. They show that the sampling strategy should be carefully chosen and designed depending on the final aim of the study and on the watershed characteristics (in particular its hydrological dynamics). This study may help to design future monitoring on water quality.

International audience; The monitoring of freshwaters regarding organic micropollutants such as pesticides requires efficient analytical methods to determine reliable concentrations at low levels in natural waters. In this aim, two complementary methods were developed for the determination of several pesticides in surface waters using Stir Bar Sorptive Extraction (SBSE) followed by liquid chromatography or gas chromatography coupled to tandem mass spectrometry. These two methods were validated and their analytical uncertainties were determined according to French standards. Linearity and limits of quantification (LOQ) were statistically tested and the efficiency, repeatability and expanded uncertainties were evaluated for each compound. The SBSE-TD-MS-MS method achieved lower LOQ although the number of compounds analyzed was lower than for the SBSE-LD-UHPLC-MS-MS method.

International audience

International audience; One dimensional physically based models are widely use as regulatory tools for pesticide leaching in the E.U. However, in the particular case of drained soils, water and solute flow are mainly influenced by the 2D-spatial dynamics of the drained water-table (Paris, 2004). On the other hand, preferential flow is often invoked (Jarvis, 2007) to explain the observation of quick pesticide transfer to the drain. The main objective of this study is to evaluate the role of the drained water table and preferential flow in pesticide export, comparing a one dimensional model and a two dimensional model. The la Jaillière experimental station is located in the western part of France (47°27' N, 0°57' W). The site has been monitored for pesticides since 1994 and provides an important data set on pollutant transfers. It is currently used as a drainage scenario for European pesticide registration. The soils are predominantly stagnic luvisol, occurring on a gently sloping plateau. The fields are tile drained according to French criteria (0.9 m deep and 10-12 m drain spacing). The study is focused on one plot of the domain, called "T4", whose characteristics are provided in Table 1. Table 1 : Main soil characteristics of the T4 plot. Horizon Thickness Clay (%) Silt (%) Sand (%) O.M (%)a Bulk density (g.cm3) pH (water) Structure Ap 30 20.8 44.6 34.6 2.17 1.55 6.3 Blocky E 18 25.9 41.3 32.8 0.77 1.63 7 Blocky Bt 17 49.2 35.3 15.5 0.46 1.7 5.6 Prismatic Bt/C 45 42.7 35.8 21.5 0.36 1.7 4.9 Blocky The fate of two substances with widely differing characteristics was investigated. The first, isoproturon, is moderately sorbed (Koc : 124 L.Kg-1) and weakly persistent in soils (DT50 : 15 Days) whereas the second, diflufenican has a high sorption capacity (Koc : 2000 L.Kg-1) and is slightly persistent in the environment with DT50 exceeding 140 days. Both substances are applied during autumn on winter-wheat. The two models tested in this study were MACRO 5.2 (Larsbo and Jarvis, 2003) and HYDRUS-2D (Simunek et al., 1999). MACRO is a one dimensional physically based model with the soil porosity divided into two flow domains (macropores and micropores). Richard's equation and the classic convection-dispersion equation (CDE) are used in the matrix, for water and solute transport, respectively. In the macropore domain, a kinematic wave approach is used for water flow and convection for solute transport. HYDRUS-2D is a two dimensional physically based model which allows users to choose from a range of hydraulic models (e.g single porosity, mobile-immobile water). In order to investigate preferential flow impact on pesticide transport, we decided to test a single porosity model and a dual permeability model developed by Gerke and van Genuchten (1993) using Richard's equationand the CDE in both domains of porosity. According to EU procedures (FOCUS, 2001), models were first calibrated against water flow and bromide for which hourly data sets are available. Bromide has been use in several studies to investigate and calibrate the mass transfer coefficient (e.g. Stenemo and Jarvis 2007; Kohne et al., 2006) and other parameters (tortuosity, disperivity, etc) which were evaluated here. Results show that both models underestimated drainage during the intensive drainage season (IDS) without appropriate calibration. Another difficulty of the site is to represent the role of the groundwater table on drainage intensity and depletion. Simulation of bromide shows discrepancies between models, MACRO can't' represent simultaneously the dynamic of both water and bromide as shown on Fig. 1. Thus, the mass transfer coefficient can not be estimated with certainty. On the other hand, HYDRUS-2D represents the water and solute dynamics well for both options. Consequences for pesticide export are assessed using the mass transfer coefficient calibrated with HYDRUS-2D and MACRO.

This report presents the author's researchs, dealing with pesticides transfer towards fresh water studying and modelling. It is organized in three parts : • Assessing man made elements' influence on pesticides tranfer, especially considering ditches and vegetated buffer zones. • Better understanding how concentration data in surface water allow to really assess water exposition • Modeling pesticides transfer towards surface water at a bigger scale than the plot one : hillslope or catchment / Ce rapport présente les travaux menés par l'auteur depuis autour des questions spécifiques que posent l'étude et la modélisation du transfert des produits phytosanitaires vers les eaux de surface. Il ess organisé selon trois axes complémentaires : • Evaluer l'influence des éléments du paysage sur les transferts de pesticides, notamment pour les fossés et les zones tampons enherbées, • Contribuer à mieux cerner en quoi les données de concentrations acquises dans le milieu aquatique renseignent effectivement sur l'exposition du milieu et, en retour, le type de résultats de modélisation utiles pour caractériser l'exposition et permettre d'établir un lien avec l'impact sur les écosystèmes aquatiques, • Alimenter la réflexion sur la modélisation du transfert des pesticides vers les eaux de surface à une échelle dépassant celle de la parcelle : versant ou bassin versant.

/ La préservation des eaux de surface représente une préoccupation socio-économique majeure, symbolisée entre autres par la mise en ½uvre en 2000 de la Directive Cadre Européenne sur l'Eau (DCE, 2000), qui impose le retour au « bon état » chimique et écologique des masses d'eau d'ici à 2015. Cette contrainte législative a engendré (et engendre toujours) des besoins de recherche nombreux, notamment pour améliorer les procédures d'évaluation des risques écotoxicologiques des substances chimiques dans les masses d'eau, définir des mesures correctives visant à améliorer la qualité chimique des eaux, et développer des outils permettant de réellement mesurer le gain écologique découlant de ces améliorations. Plus récemment, le Grenelle de l'Environnement a confirmé au niveau national cette forte prise de conscience sociétale, en particulier avec l'élaboration du plan Ecophyto 2018 visant à réduire l'usage des produits phytosanitaires en agriculture. L'ensemble de mes recherches, débutées en 2003 dans le cadre de mon Doctorat, s'inscrit dans cette problématique finalisée de gestion des eaux. Elles concernent principalement les petits cours d'eau de tête de bassins versants, très sensibles aux diverses pressions anthropiques et notamment aux contaminations par les polluants chimiques organiques ou inorganiques. Dans ces milieux lotiques, la majorité de l'activité microbienne est assurée par les communautés benthiques, à savoir les biofilms se développant sur des substrats inertes (artificiels ou naturels) ou organiques (litières de feuilles) et les communautés sédimentaires. Ces communautés microbiennes interviennent ainsi dans des processus écologiques majeurs tels que la régulation des cycles biogéochimiques ou l'auto-épuration de zones contaminées (Battin et al., 2003). Elles interagissent précocement avec les substances dissoutes, et notamment les toxiques, et présentent une forte capacité à répondre rapidement aux changements environnementaux et à s'y adapter de manière transitoire ou irréversible (Sabater et al., 2007). En outre, ce sont des assemblages complexes, composés de microorganismes autotrophes et hétérotrophes qui présentent des sensibilités différentes selon le mode d'action des toxiques rencontrés. De par ces différentes caractéristiques, ils offrent donc un potentiel important pour évaluer l'impact écologique des toxiques dans les cours d'eau. Dans ce contexte, mes recherches ont pour cadre très général l'évaluation de la réponse structurale et fonctionnelle des communautés microbiennes aquatiques benthiques à des niveaux variables d'exposition à des pesticides organiques et inorganiques.

/ La contamination des eaux de surface par les substances phytosanitaires représente une menace tant pour la santé humaine que pour l'intégrité des écosystèmes aquatiques et elle peut remettre en cause les usages de l'eau. Même si l'agriculture n'est pas la seule en cause, elle utilise plus de 90% du tonnage total des produits commercialisés en France et concerne plus de 14 millions d'hectares au niveau national. La contamination des eaux de surface résulte à la fois de pollutions dites ponctuelles, liées aux pratiques de manipulation et d'application des produits, et de pollutions dites diffuses liées à l'entraînement des substances appliquées par l'eau (ruissellement, infiltration, drainage) ou l'air. Ce dernier type de pollution est plus difficile à quantifier et à maîtriser de par son caractère aléatoire et du fait du grand nombre de processus et de facteurs impliqués. Dans ce contexte, l'Equipe Pollutions Diffuses du Cemagref/Irstea, au sein de laquelle s'inscrivent mes activités, vise à améliorer la compréhension, la quantification et la limitation des transferts hydriques diffus des substances phytosanitaires vers les eaux de surface. Je décris dans ce mémoire les recherches que j'ai réalisées, encadrées ou animées en collaboration avec mes collègues du Cemagref et d'autres organismes de recherche (INRA, Universités, CNRS, ...), ce à trois niveaux d'observation : i) l'échelle locale, pour l'étude de la genèse du ruissellement et de l'entraînement des substances en phases liquide et solide, ii) l'échelle intermédiaire, pour l'étude du transfert et de la rétention des substances au sein de fossés agricoles - éléments du paysage très fréquents en milieu cultivé et connexions hydrauliques directes entre parcelles et milieux aquatiques, et iii) l'échelle du bassin versant pour l'étude de la contamination résultante au sein des petits cours d'eau. Dans l'approche de tels systèmes, je m'attache à mettre en avant l'importance de mieux prendre en compte conjointement les processus hydrologiques et chimiques et leurs dynamiques temporelles spécifiques. Je confirme également l'intérêt de mener des études à différentes échelles spatiales complémentaires - le changement d'échelle de la parcelle au petit bassin pouvant induire une forte modification des flux et des concentrations en aval. Par ailleurs, la grande variabilité spatio-temporelle des chroniques de concentration met en exergue la difficulté de l'échantillonnage au sein des petits cours d'eau et le besoin de développer des stratégies et des outils diversifiés pour mieux mesurer la qualité de l'eau et répondre aux différents objectifs des gestionnaires tels que la caractérisation de l'état chimique des milieux aquatiques ou de l'impact d'actions correctives. Ces résultats mettent également en évidence le besoin de développer des outils (modèles, indicateurs) qui permettent de mieux évaluer le risque lié à l'utilisation des produits phytosanitaires pour les écosystèmes, à travers une meilleure prise en compte des relations pression-exposition-impact intégrant la vulnérabilité des milieux, l'objectif, in fine, étant de dégager des pistes pour la limitation et la gestion de ce risque. Malgré la complexité croissante engendrée, ces travaux montrent l'intérêt de mener des recherches en conditions naturelles et dans des situations variées afin de mieux cerner les types de réponses réelles du milieu, même si des études plus fines et mieux contrôlées en laboratoire s'avèrent utiles pour vérifier les hypothèses formulées sur le terrain. Enfin, j'insiste sur l'importance de pouvoir disposer de sites de recherche fédérateurs permettant d'associer des démarches pluridisciplinaires (hydrologie, chimie de l'environnement, biologie, agronomie, systèmes d'information, informatique, modélisation) et pluri-acteurs autour d'objectifs partagés ou complémentaires.

International audience; In France, agriculture uses large quantities of fertilizer and pesticides. Water contamination by pesticides is highlighted by monitoring networks, at local and national levels. Control and reduction of contamination are major issues, for the protection of drinking water resources and aquatic ecosystems. Thus, understanding and quantifying the mechanisms involved in mobilization, transfer and dissipation of these substances can help to perform risk of water contamination diagnosis, and to estimate the effectiveness of corrective solutions.