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International audience; Plastic pollution is present in most marine environments; however, contamination in pelagic predators, including species of economic interest, is still poorly understood. This study aims to access the macro-and microplastic contamination in tuna and large pelagic species and verify whether a trophic transfer occurs from prey to tunas captured by two fleets in the Southwestern Tropical Atlantic (SWTA). We combined different methodological approaches to analyse the intake of macro-and microplastics. In addition to examining the plastics in the fish' stomachs, we investigated the contamination in the prey retrieved from the guts of predators. A low frequency of occurrence (3%) of macroplastic was detected in the tuna and large pelagic species; conversely, we observed a high frequency of microplastic in the tuna's stomachs (100%) and prey analysed (70%). We evinced the trophic transfer of microplastics by analysing the ingestion rate of particles in prey retrieved from the tuna stomachs. In the 34 analysed prey, we detected 355 microplastic particles. The most contaminated prey were cephalopods and fishes of the Bramidae family. The most frequent microplastic shapes in both prey and tuna stomachs were foams, pellets and fibres (< 1 mm). A variety of polymers were identified; the most frequent were styrene-butadiene rubber (SBR), polyamide (PA), polyethylene terephthalate (PET) and polyethylene (PE). Our findings enhance scientific knowledge of how the ecological behaviour of marine species can affect microplastics intake.

International audience; Here, we evaluate for the first time the performances of the newly developed laser direct infrared (LDIR) technique and propose an optimization of the initial protocol for marine microplastics (MPs) analysis. Our results show that an 8 μm porosity polycarbonate filter placed on a Kevley slide enables preconcentration and efficient quantification of MPs, as well as polymer and size determination of reference plastic pellets of polypropylene (PP), polyethylene (PE), polystyrene (PS), polyvinyl chloride (PVC), and polyethylene terephthalate (PET), with recoveries ranging from 80–100% and negligible blank values for particle sizes ranging from 200 to 500 μm. A spiked experiment using seawater, sediment, mussels, and fish stomach samples showed that the method responded linearly with significant slopes (R2 ranging from 0.93–1.0; p < 0.001, p < 0.01). Overall, 11 polymer types were identified with limited handling and an analysis time of ca. 3 h for most samples and 6 h for complex samples. Application of this technique to Mediterranean marine samples (seawater, sediment, fish stomachs and mussels) indicated MP concentrations and size distribution consistent with the literature. A high predominance of PVC (sediment, fish stomachs) and PE and PP (seawater, mussels) was observed in the analyzed samples.

Plastic pollution in freshwater ecosystems, including microplastics (MPs) smaller than 5 mm, has become an emerging global concern. Asia is considered a "hot spot" for plastic pollution due to rapid economic and demographic growth, together with rapid urbanization. Here, we provide an overview of the current knowledge on MP abundance, sources, fate, and transfer in Asian freshwater ecosystems based on publications from January 2014 to May 2021. MP contamination in freshwater compartments, including water, sediment, and biota, was found to vary strongly. In water, it ranged from 0.004 items m

Made available in DSpace on 2022-04-29T08:38:46Z (GMT). No. of bitstreams: 0 Previous issue date: 2022-01-01 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Fundação de Amparo à Ciência e Tecnologia do Estado de Pernambuco Microplastics are a relevant environmental concern in marine ecosystems due to their ubiquity. However, knowledge on their dispersion patterns within the ocean basin and the interaction with biota are scarce and mostly limited to surface waters. This study investigated microplastic contamination in two species of deep-sea cephalopods from the southwestern Atlantic with different ecological behaviour: the vampire squid (Vampyroteuthis infernalis) and the midwater squid (Abralia veranyi). Microplastic contaminated most of the evaluated specimens. V. infernalis showed higher levels of contamination (9.58 ± 8.25 particles individual−1; p < 0.05) than A. veranyi (2.37 ± 2.13 part. ind.−1), likely due to the feeding strategy of V. infernalis as a faecal pellets feeder. The size of extracted microplastics was inversely proportional to the depth of foraging. The microplastics were highly heterogeneous in composition (shape, colour and polymer type). Our results provide information regarding microplastic interaction with deep-sea organisms and evidence of the biological influence in the microplastic sinking mechanism. Departamento de Pesca e Aquicultura (DEPAQ) da Universidade Federal Rural de Pernambuco (UFRPE), Rua Dom Manuel de Medeiros, s/n Université de Toulon Aix Marseille Univ. CNRS IRD MIO Institut de Recherche pour le Développement (IRD) MARBEC Univ Montpellier CNRS Ifremer IRD Universidade Estadual Paulista Júlio de Mesquita Filho (UNESP) UNESP CLP Instituto de Biociências, Campus do Litoral Paulista Universidade Estadual Paulista Júlio de Mesquita Filho (UNESP) UNESP CLP Instituto de Biociências, Campus do Litoral Paulista CNPq: 305014/2016-1 CNPq: 312211/2017-1 Fundação de Amparo à Ciência e Tecnologia do Estado de Pernambuco: BFP-0049-5.06/20 Fundação de Amparo à Ciência e Tecnologia do Estado de Pernambuco: BFP-0107-5.06/21

Microplastics (MPs

Plastic garbage patches at the ocean surface are symptomatic of a wider pollution affecting the whole marine environment. Sinking of plastic debris increasingly appears to be an important process in the global fate of plastic in the ocean. However, there is insufficient knowledge about the processes affecting plastic distributions and degradation and how this influences the release of additives under varying environmental conditions, especially in deep-sea environments. Here we show that in abiotic conditions increasing hydrostatic pressure inhibits the leaching of the heaviest organic additives such as tris(2-ethylhexyl) phosphate and diisononyl phthalate from polyethylene and polyvinylchloride materials, whereas deep-sea and surface marine prokaryotes promote the release of all targeted additives (phthalates, bisphenols, organophosphate esters). This study provides empirical evidences for more efficient additive release at the ocean surface than in deep seawater, where the major plastic burden is supposed to transit through before reaching the sediment compartment., Plastics are major marine pollutants, and while research suggests that they can release potential harmful additives into seawater, how environmental conditions influence this is unknown. Here the authors determine that byproducts released from microplastics are less under deep-sea conditions versus surface.

International audience; The ubiquity of microplastics (MPs) has now been demonstrated throughout Earth’s geographic areas in both terrestrial and marine environments. Marine ecosystems are the end point of the plastic waste cycle, and marine sediments are increasingly considered to be a sink for plastic debris, with possible deleterious effects on seafloor ecosystems. However, the low concentration of MPs in a complex matrix such as marine sediment makes their reliable analysis difficult. MP concentration in marine sediments is usually determined by various extraction procedures followed by optical, spectroscopy or mass spectrometry techniques, and are therefore hard to compare. Therefore, reliable determination of MPs in sediment is a challenging task. Here we present a short review on studies dealing with analytical determination protocols and MP detection in marine sediments and discuss the advantages of the different techniques used. This analysis of the literature reveals that most of the 70 studies were carried out in European and Asian coastal environments. The use of NaCl saturated solution, hydrogen peroxide (H2O2) and Fourier transform infrared spectroscopy (FTIR) are by far the most-used techniques for the different steps of separation, digestion and identification, respectively. Based on this body of literature, we present recommendations and suggestions for future research in order to increase the reliability of results and to facilitate inter-comparison. The use of NaCl saturated and H2O2 solution is strongly recommended for the separation and digestion steps, respectively, whereas during the filtration step it is necessary to choose filter type based on the identification technique. More thorough investigation is needed to establish a systematic protocol for MP identification. A combination of techniques would permit to identify all items, and personal bias could be avoided if automatic identification was implemented. Nanoplastics (NP) occurrence in marine sediments is also discussed, although no data are available to date.

[Departement_IRSTEA]Eaux [TR1_IRSTEA]BELCA; International audience; Glyphosate (PMG) is one of the most widely used herbicides with a reported 8.6 million tons applied globally in 2016. Due to widespread use and limited understanding of long-term environmental impacts, it is expected that future monitoring requirements for PMG and its primary metabolite aminomethyl phosphonic acid (AMPA) in aquatic environments will increase, along with the need for low cost monitoring and risk assessment strategies. The aim of this study was to investigate a microporous polyethylene tube (MPT; 2-mm thickness, 17.6 cm2 surface area, 35% porosity, 2.5 μm pore size) as a diffusive layer for the passive sampling of PMG and AMPA. Levels of PMG and AMPA sorbed to MPT were low ($K_{mw}$ close to 1 mL $g^{−1}$), validating MPT as a diffusive layer. Uptake experiments were conducted first under controlled laboratory conditions (pH = 6.8, 6 days), followed by an in situ freshwater lake system deployment (pH = 7.3, 11 days). PMG and AMPA accumulated linearly (slope relative standard deviation < 6%) under laboratory conditions with sampling rates ($R_s$) of 18 and 25 mL d$^{−1}$, respectively. PMG in situ $R_s$ was 28 mL $d^{-1}$, and was not different from the one found in the laboratory. AMPA was below the limit of quantification (LOQ, 1 ng mL$^{−1}$) in grab water samples, but was detected (>LOQ) in all passive samplers. Results illustrate the gain in sensitivity provided by the passive sampling technique, and the applicability of the device developed for the passive sampling of PMG and AMPA.

International audience; We present here a comprehensive study (1-year regular sampling) on the occurrence of major families of organic plastic additives in the Rhône River surface waters. Potential sources and contaminant export are also discussed. A total of 22 dissolved phase samples were analyzed for 22 organic additives mainly used in the plastic industry, including organophosphate esters (OPEs), phthalates (PAEs) and bisphenols (BPs). Our results indicate that PAEs were the most abundant class, with concentrations ranging from 97 to 541 ng L À1 , followed by OPEs (85e265 ng L À1) and BPs (4e21 ng L À1). Among PAEs, diethylhexyl phthalate (DEHP) was the most abundant compound, whereas TCPP (Tris(1-chloro-2-propyl) phosphate) and TnBP (Tri(n-butyl)phosphate) were the predominant OPEs. Bisphenol S was the only BP detected. 5 e54 metric tons year À1 of dissolved organic plastic additives of emerging concern are estimated to be exported to the Gulf of Lion by the Rhône River, which is the main freshwater source of the Mediter-ranean Sea.

International audience; The present study reports on observations carried out in the Tropical North Atlantic in summer and autumn 2017, documenting Sargassum aggregations using both ship-deck observations and satellite sensor observations at three resolutions (MSI-10 m, OLCI-300 m, VIIRS-750 m and MODIS-1 km). Both datasets reported that in summer, Sargassum aggre-gations were mainly observed off Brazil and near the Caribbean Islands, while they accumulated near the African coast in autumn. Based on in situ observations, we propose a five-class typology allowing standardisation of the description of in situ Sargassum raft shapes and sizes. The most commonly observed Sargassum raft type was windrows, but large rafts composed of a quasi-circular patch hundreds of meters wide were also observed. Satellite imagery showed that these rafts formed larger Sargassum aggregations over a wide range of scales, with smaller aggregations (of tens of m 2 area) nested within larger ones (of hundreds of km 2). Match-ups between different satellite sensors and in situ observations were limited for this dataset, mainly because of high cloud cover during the periods of observation. Nevertheless, comparisons between the two datasets showed that satellite sensors successfully detected Sargassum abundance and aggregation patterns consistent with in situ observations. MODIS and VIIRS sensors were better suited to describing the Sargas-sum aggregation distribution and dynamics at Atlantic scale, while the new sensors, OLCI and MSI, proved their ability to detect Sargassum aggregations and to describe their (sub-) mesoscale nested structure. The high variability in raft shape, size, thickness, depth and biomass density observed in situ means that caution is called for when using satellite maps of Sargassum distribution and biomass estimation. Improvements would require additional in situ and airborne observations or very high-resolution satellite imagery.

International audience; Four perfluoroalkyl substances (PFAS) were analyzed in 62 duplicate surface water samples from the Rhône River and Marseille Bay (France; NW Mediterranean Sea). Perfluorooctane sulfonate (PFOS) was detected in all samples and exceeded the European Environmental Quality Standard (EQS) values in over 80% of the cases. The most contaminated samples were from the Rhône River (up to 200 ng L-1 ∑ 4 PFAS), as well as those collected near a wastewater treatment plant outlet in Marseille Bay (up to 9 ng L −1 ∑ 4 PFAS). While PFOS was the predominant PFAS in Marseille Bay, remarkably high concentrations of perfluorohexanoic acid (PFHxA) were measured in the Rhône River (8-193 ng L −1). The relative abundances of individual compounds differed thus significantly between the Rhône River and Marseille Bay, indicating different sources. A simulation made with the MARS3D model showed that PFOS inputs from the Rhône River can enter Marseille Bay at levels > EQS.

International audience; The release of emerging organic contaminants is identified among the most critical hazards to the marine environment, and plastic additives have received growing attention due to their worldwide distribution and potential deleterious effects. Here, we report dissolved surface water concentrations of two important families of plastic additives (organophosphate esters (OPEs) and bisphenols) and other related organic compounds (perfluorinated chemicals) measured in the North Atlantic from Cape Verde to the West Indies. We found that OPEs were the most abundant contaminants, reaching remarkably high concentrations in open ocean waters (1200 km offshore of the American Coast, at the location of the Amazon river plume during the sampling period), with up to 1.3 μg L–1 (Σ9OPEs). A Lagrangian analysis confirmed that these high concentrations of contaminants originated from the Amazon River plume and were transported more than 3000 km by the North Brazil Current and its retroflection. We thus consider the Amazon River as a major source of organic contaminants of emerging concern to the tropical North Atlantic Ocean and suggest that medium-/long-range contaminant transport occurs, most certainly facilitated by the highly stratified conditions offered by the river plume.

International audience; Plastic debris in the environment contains plasticizers, such as phthalates (PAEs), that can be released during plastic aging. Here, two common plastic materials, an insulation layer of electric cables (polyvinyl chloride, PVC-cables) and plastic garbage bag (polyethylene, PE-bags), were incubated in natural seawater under laboratory conditions, and the PAE migration to the seawater phase was studied with varying light and bacterial conditions over a 90-day time course. Free PAEs diluted in seawater were also studied for bacterial degradation. Our results showed that, within the first month of incubation, both plastic materials significantly leached out PAEs into the surrounding water. We found that di-isobutyl phthalate (DiBP) and din -butyl phthalate (DnBP) were the main PAEs released from the PE-bags, with the highest values of 83.4 ± 12.5 and 120.1 ± 18.0 ng g −1 of plastic, respectively. Furthermore, dimethyl phthalate (DMP) and diethyl phthalate (DEP) were the main PAEs released from PVC-cables, with mass fractions as high as 9.5 ± 1.4 and 68.9 ± 10.3 ng g −1 , respectively. Additionally, we found that light and bacterial exposure increased the total amount of PAEs released from PVC-cables by a factor of up to 5, whereas they had no influence in the case of PE-bags.

International audience; A rapid analytical method including one-single solid-phase extraction (SPE) procedure followed by gas and liquid chromatography coupled with high resolution mass spectrometry detection (GC–MS and LC–HRMS respectively) was developed for the quantification of 40 organic compounds (1.6 < log K ow < 9.5) in seawater including both legacy and emerging contaminants, with a focus on the most common plastic organic additives. This new method allowed for the analyses of nine organophosphate esters (OPEs), seven phthalates (PAEs), six bisphenols (BPs), five perfluorinated compounds (PFCs), and thirteen legacy organochlorinated compounds (OCs, including polychlorobiphenyles and pesticides) with recoveries in the ranges of 57–124% for OPEs, 52–163% for PAEs, 64–118% for BPs, 63–124% for PFCs, and 40–95% for OCs. As a result of (i) strict cleanup protocols, (ii) material, and solvent selection, and (iii) the use of an ISO 6 cleanroom for sample treatment, the procedural blank levels were always lower than 5 ng L −1 , even for the most abundant and ubiquitous compounds like tris-(2-chloro, 1-methylethyl) phosphate (TCPP) and diethylhexyl phthalate (DEHP). The quantification limits were in the ranges of 0.03–0.75 ng L −1 for OPEs, 0.03–0.25 ng L −1 for PAEs, 0.1–5 ng L −1 for BPs, 0.1–8 ng L −1 for PFCs, and 0.02–1.1 ng L −1 for OCs, matching seawater analysis requirements. Dissolved water phase samples collected in Marseille Bay (NW Mediterranean Sea) were analyzed using the developed method reveling the concentration of PAEs up to 140 ng L −1 (DEHP) and that of OCs up to 70 ng L −1 (α-endosulfan). For the first time, we also provided the concentrations of OPEs (TCPP up to 450 ng L −1), BPs (bisphenol S up to 123 ng L −1), and PFCs (PFOS up to 5 ng L −1) in this area. A sampling station close to the municipal waste water treatment plant outfall exhibited the highest concentration levels for all compounds.

[Departement_IRSTEA]Eaux [ADD1_IRSTEA]Systèmes aquatiques soumis à des pressions multiples; International audience; The work presented here aims at comparing monitoring of S-metolachlor, the major pesticide in use in the Arcachon Bay (South West of France, transitional coastal area), by chemical analysis (monthly passive sampling) and contaminant dissipation modeling from sources (Mars-2D model). The global strategy consisted in i) identifying the major sources of S-metolachlor to the Bay, ii) monitoring these sources for 12 months, and iii) comparing modeled data in the Bay based on measured inputs, to chemical measurements made inside the Bay along with the 12-month source monitoring. Results first showed that the major S-metolachlor surface inputs to the Arcachon Bay are mainly from one single source. Modeled and measured data were in good agreement at 5 sites in the Bay, both in terms of concentration range and seasonal trends. Modeling thus offers a cost-effective solution for monitoring contaminants in transitional waters, overcoming in addition the technical limitations for measuring pg L −1 or lower levels in coastal waters. However, we highlighted that secondary sources may affect accuracy at local level.

International audience; Marine litter such as microplastics pose a variety of problems once they reach the environment via improper waste disposal or spills, among others. While microplastics are often ingested by marine organisms, marine life is not only threatened by the physical damage plastic items can cause but also by the possible chemical pollution resulting from the leaching of plastic additives or other adsorbed chemicals on the plastics surface during long-range transport. Plastic additives include plasticizers, flame retardants and colour pigments. The demonstrated toxicity of some of these molecules has led to national and international legislations limiting or banning their use. However, a wide variety of substances are still found in plastic products and little is known about their impact on the marine and terrestrial environment.

This paper presents an optimization of the pharmaceutical Polar Organic Chemical Integrative Sampler (POCIS-200) under controlled laboratory conditions for the sampling of acidic (2,4-dichlorophenoxyacetic acid (2,4-D), acetochlor ethanesulfonic acid (ESA), acetochlor oxanilic acid, bentazon, dicamba, mesotrione, and metsulfuron) and polar (atrazine, diuron, and desisopropylatrazine) herbicides in water. Indeed, the conventional configuration of the POCIS-200 (46 cm(2) exposure window, 200 mg of Oasis® hydrophilic lipophilic balance (HLB) receiving phase) is not appropriate for the sampling of very polar and acidic compounds because they rapidly reach a thermodynamic equilibrium with the Oasis HLB receiving phase. Thus, we investigated several ways to extend the initial linear accumulation. On the one hand, increasing the mass of sorbent to 600 mg resulted in sampling rates (R s s) twice as high as those observed with 200 mg (e.g., 287 vs. 157 mL day(-1) for acetochlor ESA). Although detection limits could thereby be reduced, most acidic analytes followed a biphasic uptake, proscribing the use of the conventional first-order model and preventing us from estimating time-weighted average concentrations. On the other hand, reducing the exposure window (3.1 vs. 46 cm(2)) allowed linear accumulations of all analytes over 35 days, but R s s were dramatically reduced (e.g., 157 vs. 11 mL day(-1) for acetochlor ESA). Otherwise, the observation of biphasic releases of performance reference compounds (PRC), though mirroring acidic herbicide biphasic uptake, might complicate the implementation of the PRC approach to correct for environmental exposure conditions.

International audience

The authors are grateful to Adeline Charriau, Sophie Lissalde, Remy Buzier, Gilles Guibaud from GRESE laboratory, University of Limoges; Helene Budzinski from EPOC-LPTC laboratory, University of Bordeaux; and Josephine Chastang for their scientific support.; International audience; Glyphosate is the most widely used herbicide on a world scale for the last 40 years, for both urban and agricultural use. Here we describe the first passive sampling method for estimating, the concentration of glyphosate and AMPA (aminomethyl phosphonic acid, one of its Major degradation products) in surface water. The sampling method is based on a newly developed configuration of the diffusive gradient in thin-film (DGT). technique, which includes a TiO2 binding phase, already in use for a wide range of anions. Glyphosate and AMPA were retained well on a TiO2 binding phase, and elution in a 1 mL of 1 M NaOH led to recoveries greater than 65%. We found no influence of pH or flow velocity on the diffusion coefficients through 0.8 min polyacrylamide gel, although they did increase with temperature. TiO2 binding gels were able to accumulate up to 1167 ng of P for both glyphosate and AMPA, and linear accumulation was expected over several weeks, depending on environmental conditions. DGT sampling rates were close to 10 mL day(-1) in ultrapure water, while they were less than 1 mL day(-1) in the presence of naturally occurring ions (e.g., copper, iron, calcium, magnesium). These last results highlighted (i) the ability of DGT to measure only the freely dissolved fraction of glyphosate and AMPA in water and (ii) the needs to determine which fraction (total, particulate, dissolved, freely dissolved) is indeed bioactive.

International audience; Acidic herbicides are increasingly monitored in freshwater, since their high solubility favors their rapid transfer to the water phase. Therefore, contaminant levels in the water can vary rapidly and passive sampling would be preferred over spot sampling to integrate all pollution events over a given exposure time. In this work, we propose to compare the conventional pharmaceutical polar organic chemical integrative sampler (POCIS) with modified POCISs containing two different receiving phases: a standard polystyrene divinylbenzene polymer with a higher specific surface area (Chromabond HR-X) and a mixed-mode anion exchange sorbent providing additional strong anion exchange interaction sites (Oasis MAX). Due to its hydrophobic character, Chromabond HR-X had little interaction with water (no sampling of acidic herbicides); whereas Oasis MAX provided acceptable sampling parameters (longer kinetic regime together with higher sampling rates). Additional experiments with POCIS-MAX showed no influence of nitrates on analyte uptakes, and linear isotherms reaching 10 μg L−1, supporting the applicability of this device for the sampling of organic acids in continental water. The performance and reference compound (PRC) approach would be then applicable for POCIS-MAX if no competition is observed with other anions, especially organic acids (e.g., humic acids).

International audience; The Leyre River is the main tributary to the Bassin d’Arcachon lagoon. Herbicides belonging to the chloroacetanilide class have been found in the river (S-metolachlor and acetochlor) as well as some of their metabolites at higher concentrations. As the environmental toxicity of these molecules is not well known, ecotoxicological tests have been carried out on river periphyton at different levels of biological diversity: from the clone of one diatom species (Nitzschia nana) to the population of the same species (several clones) up to the multi-specific species community dominated by diatoms. Moreover, tests were performed on diatoms coming from an unpolluted upstream site and from a contaminated downstream site, in order to investigate possible tolerance acquisition to pollutants. The method consisted in measuring diatom growth inhibition at different doses of each substance from the increase of chlorophyll-a concentration after 4 days. It resulted that acetochlor was clearly more toxic than S-metolachlor at all levels of biological diversity. EC50 values estimated from the tests suggest no effect of contaminants on diatom growth or biomass in the river. The toxicity of the metabolites appeared very low compared to that of their parent compounds. No difference in tolerance to the herbicides was demonstrated between summer diatom communities from the two sites in spite of different specific compositions. However, concerning the populations of N. nana isolated in winter following the highest herbicide concentrations in the river (about 0.5 mg L1), the downstream population showed a higher tolerance to acetochlor but there was no co-tolerance to S-metolachlor. Thus, it appeared that acetochlor represents the highest toxic pressure on periphyton among the other contaminants in the Leyre River.

Diatoms are commonly used as bioindicators of trophic and saprobic pollution in rivers. However, more knowledge is needed concerning their sensitivity to toxicants such as agricultural herbicides. In this study, seven species of periphytic diatoms were isolated from the Morcille River (Beaujolais area, France) which presents a streamward contamination gradient by pesticides and particularly diuron. The sensitivity of these species to diuron was assessed through ecotoxicological tests based on short-term growth inhibition of monospecific cultures. After application of an appropriate toxicological model, EC50 were determined and the species were ranked according to their tolerance. EC50 values ranged from 4.5 to 19 μg L(-1). Finally, the results were related to field periphyton samples from an upstream and a downstream site in order to check if variations in specific relative abundance between sites are consistent with differences in tolerance to diuron. Species distribution between sites was only partially in accordance with toxicological results suggesting that other factors (toxic or trophic) have an important influence on diatom communities in the river. Nevertheless, diatoms showed their potential to indicate water contamination by pesticides and toxic indices could be developed in complement to existing trophic indices.

International audience; The aim of this study is to propose an analytical method for determining different classes of pesticides in water using LC-ESI-MS/MS. Two techniques of field-sampling and analyte extraction were used: solid phase extraction (SPE) of water samples from active sampling and field exposure of Polar Organic Chemical Integrative Samplers (POCIS). We have worked with thirty-three molecules representing eight pesticide classes: carbamates, chloroacetanilides, dicarboximides, morpholines, organophosphorous, phenylureas, strobilurines and triazines. First, liquid chromatography separation protocols and the optimization of the ESI-MS/MS parameters were developed. Then, the SPE step was optimized to obtain acceptable levels of recovery for the various classes of molecules. The matrix effect that may significantly lower the ionization efficiency with ESI interfaces was evaluated and minimized. The performances (limits of quantification, accuracy and precision) of the SPE and POCIS techniques were evaluated, and a comparison between the active and passive sampling techniques was carried out with a field application.