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EGU General Assembly 2021, ONLINE, , 19-/04/2021 - 30/04/2021; Rivers are major pathways of plastics from lands into the Ocean. However, there is still a huge lack of knowledge on how riverine litter, including macroplastics, is transferred into the Ocean. Quantitative measurements of macroplastic emissions in rivers even suggest that a small fraction (0.001 to 3%) of the Mismanaged Plastic Waste (MPW) generated within a river basin finally reach the sea. Instead, macroplastics may remain within the catchment and on coastlines because of complex transport dynamics that delay the transfer of plastic debris. In order to better understand those dynamics, we performed tracking of riverine litter over time. First, hundreds of date-prints items were collected on riverbanks in the Seine estuary. The distribution of their Use-By-Dates suggest that riverine litter may remain stored on riverbanks for decades. Second, we performed real time tracking of floating and sub-floating bottles using GPS-trackers. Between March 2018 and April 2019, 39 trajectories were recorded in the estuary under tidal influence and 11 trajectories upriver, covering a wide range of hydrometeorological conditions. Results show a succession of stranding/remobilization episodes in combination with alternating upstream and downstream transport in the estuary related to tides. In the end, tracked bottles systematically stranded somewhere, for hours to weeks, from one to several times on different sites. The overall picture shows that different hydrometeorological phenomena interact with various time scales ranging from hours/days (high/low tides) to weeks/months (spring/neap tides and highest tides) and years (seasonal river flow, vegetation and geomorphological aspects). Thus, the fate of plastic debris is highly unpredictable with a chaotic-like transfer of plastic debris into the Ocean. The residence time of these debris is much longer than the transit time of water. This offers the opportunity to collect them before they get fragmented and/or reach the Sea.

International audience; Polybrominated diphenyl ethers (PBDEs) were measured in plastic resin pellets collected from 65 beaches across 27 countries worldwide. They were detected at 49 locations at concentrations of the sum of 49 congeners of up to 46 ng/g-pellet and a median of 2 ng/g-pellet. These values are one to two orders of magnitude lower than those of polychlorinated biphenyls (PCBs) (median, 51 ng/g-pellet). This difference can be attributed to lower production of the Penta-BDE technical mixture, which is used extensively in some countries, and lower availability of brominated flame retardants for equilibrium partitioning than PCBs. Tetra-, penta-, and hexa-brominated congeners (BDE-47, 99, 100, 153, 154) were dominant over a deca-substituted congener (BDE-209) in many samples; this was significantly detected in pellets from some locations. Results indicate that pellets reflect the pollution status of PBDEs in the dissolved phase in seawater. From the ranking of the summed concentrations of six major PBDE congeners (Σ6PBDEs), we propose five levels of pollution categorization (ng/g-pellet): no (8.5) local pollution. The USA and neighboring countries were categorized as extreme (17–36 ng/g-pellet), western Europe and Japan were categorized as high (≤8.8), and most Asian and African countries were categorized as slight (

MICRO 2020, Fate and Impact of Microplastics : Knowledge and Responsabilities, Lanzarote, ESPAGNE, 23-/11/2020 - 27/11/2020; Rivers are supposed to be the main pathways of plastics from lands into the Ocean (Lebreton et al., 2017; Schmidt et al., 2017). However, there is still a huge lack of knowledge on how riverine litter, including macroplastics, is transferred into the Ocean. Quantitative measurements of macroplastic emissions in rivers even suggest that a small fraction (0.001 to 3%) of the Mismanaged Plastic Waste (MPW) generated within a river basin finally reach the sea (Emmerik et al., 2019; Schöneich-Argent et al., 2020; Tramoy et al. submitted). Instead, macroplastics may remain within the catchment and on coastlines because of complex transport dynamics that delay the transfer of MPW from lands into the Ocean (Olivelli et al., 2020; Weideman et al., 2020). In order to better understand those dynamics, we released 1L plastic bottles equipped with GPS-trackers in the Seine River. Between March 2018 and April 2019, 39 trajectories were recorded in the estuary under tidal influence and 11 trajectories upriver, covering a wide range of hydrometeorological conditions. Results show a succession of stranding/remobilization episodes in combination with alternating upstream and downstream transport in the estuary related to tides. In the end, 100% of the tracked bottles stranded somewhere, for hours to weeks, from one to several times at different sites. In addition, date-prints items found in historical polluted sites in the estuary confirm that plastic may remain stored on riverbanks for decades. The overall picture shows that different physical phenomena interact with various time scales ranging from hours/days (high/low tides) to weeks/months (spring/neap tides and highest tides) and years (seasonal river flow). Thus, the fate of MPW is highly unpredictable with a chaotic-like transfer of plastic debris into the Ocean, and their residence time is much longer than the transit time of water.

The dynamics of plastic debris were assessed in the Seine River, especially in the estuary, using plastic bottles equipped with GPS-trackers. In one year, 50 trajectories were recorded, covering a wide range of hydrometeorological conditions. Results show a succession of stranding/remobilization episodes in combination with alternating upstream and downstream transport in the estuary. In the end, 100% of the tracked bottles stranded somewhere, for hours or weeks, from one to several times at different sites. The overall picture shows that different physical phenomena interact with various time scales ranging from hours/days (high/low tides) to weeks/months (spring/neap tides and highest tides) and years (seasonal river flow). Thus, the fate of plastic debris is highly unpredictable, but the consequence of those interactions is that the transfer of debris is chaotic and not straightforward, and its residence time is much longer than the transit time of water.

International audience; Rivers are a major pathway for plastics between lands and the ocean. At the land-ocean interface, estuaries make the transfer dynamic of plastics complex and nonlinear. That is why very little is known about this dynamic. In this respect, a specific marker (i.e. Microlax packaging) showing date-prints was systematically investigated in different riverbanks of the Seine estuary to identify the share of "old" and "recent" litter transiting through the estuary toward the ocean. Up to 70% of Microlax were "old" plastic items probably related to the meandering dynamic of the river over large time and space scales, and hydrodynamic conditions (tides) at smaller scales. This contributes together to increase the residence time of plastics into the estuary up to decades with almost endless transport, deposit and remobilization cycles. Consequently, the Seine estuary may function as a "microplastic factory" resulting from the fragmentation of macroplastics into microplastics well before they reach the ocean.

Polycarbonate (PC) films of two different grades (Macrolon® LED 2245 and Macrolon® AL 2447) were elaborated and thermally aged at 100, 120 and 140 °C during intermediate and long times of aging. The physical aging effect on the film properties was analyzed by infrared spectroscopy, water contact angle, thermal and tensile tests, and water and gas permeation and sorption measurements. The effect of thermal treatment on PC properties was revealed, especially for the film aged at 120 °C. Aging caused a continual increase of PC glass transition temperature and relaxation enthalpy, an increase in Young's modulus and yield strength values and a decrease in the elongation at break. These results were attributed to the reduction of the free volume because of the PC conformational changes. The film barrier properties using liquid water and gas (N2, O2 and CO2) molecules as probes were studied in order to highlight the free volume evolution. It was shown that physical aging caused a reduction of water and gas permeability. This fact was mainly explained by the decrease of the solubility coefficient with the aging time increase.

Global estimations state that between 0.5 and 12.7 million metric tons of plastic enter the oceans each year. They are, however, associated with great uncertainties due to methodological difficulties to accurately quantify land-based plastic fluxes into the oceans. New studies at basin scale are thus needed for better model calibrations. Here, a modeling approach based on Jambeck’s statistical method and a field approach are compared in order to (i) quantify plastic fluxes in the Seine River and (ii) characterize and constrain uncertainties of both approaches. Despite the simplicity of the statistical approach and rough extrapolations, both methods yield similar results, i.e., between 1,100 and 5,900 t/yr of plastic litter flowing into the Sea of which about 88–128 t/yr are removed by cleaning operations. According to the marine strategy framework directive (2008/56/EC), actions are required to quantify plastic fluxes entering the oceans. Among different methods, a better use of the data from the waste collection should be considered. The development of a national and homogenous platform listing all the collects would be a first step in that direction.

Macroplastic emissions from the Seine estuary to the English Channel were estimated using institutional cleaning of riverbanks, combined with a tagged litter experiment. Cleaning were performed between March 2018 and April 2019 by the non-profit company Naturaul'un over 19 sites covering 20 km of riverbanks. A total of 365 tagged litter (90% macroplastics) was released in the estuary in March (n = 200), at the end of the winter/spring flood 2018, in July (n = 58), August (n = 56) and September 2018 (n = 51) during low river flow periods. Over the total tagged litter, 102 (28%) were recovered by Naturaul'un. Relative to the total amount of macroplastics (>5 cm) collected and the estimated amount of smaller/hidden macroplastics (>5 mm) not collected, the maximum macroplastic emission to the English Channel was estimated to be ~100–200 metric tons per year.

New polymer inclusion membranes (PIMs) based on poly(vinylidene fluoride) (PVDF) (polymer matrix), tricaprylmethylammonium chloride (Aliquat 336) (ion carrier) and 2-nitrophenyloctylether (2NPOE) (plasticizer) were successfully elaborated by casting evaporation method and used in selectively facilitated transport of Cr(VI) ions in an acidic aqueous medium. Obtained PIMs are dense and homogeneous and are characterized by intermolecular interactions of the membrane components (i.e. polymer matrix, ion carrier and plasticizer). The presence of ion carrier and plasticizer enhances the membrane flexibility and its hydrophilic character. The decrease of the PVDF melting point is ascribed to the strong electrostatic interactions between liquid compounds (i.e. ion carrier and plasticizer) and polymer chains. PVDF-based PIM with only 20 wt% of Aliquat 336 ensures almost complete transport of Cr(VI) ions from the donor to acceptor phase. Moreover, the addition of 5 wt% of plasticizer significantly increases the transport flux. Also, Cr(VI) ions are selectively recovered (~97%) from a mixture containing other heavy metal ions (Cd(II), Pb(II), Fe(III), Zn(II), Cu(II), Ni(II), Co(II)) with such PIM. Elaborated PVDF-based PIMs reveal improved transport properties compared to other polymer-based PIMs, exhibiting high stability (more than 190 h) and lifetime durability and so they are suitable for long term application.

International audience; Plastic pollution in oceans and rivers is of high concern because of its persistence in the environment and its potential impact on ecosystems. However, there is a specific lack of data in rivers. Here we present data from the Seine river banks in a historical polluted shore. Data were classified using international MSFD and OSPAR classifications. The sampled site is a quadrat of 1 m2 located downstream in the estuary in a visual maximum along a 1 km shore covered by plastics. A total of 20,259 plastic debris were individually counted, classified and weighted by category for a total mass higher than 4 kg. Half of the plastic debris in number are represented by preproduction pellets.

International audience; Global estimations state between 1 and 10 million metric tons of plastic entering the oceans each year. But, they are associated with great uncertainties due to methodological difficulties to accurately quantify plastic fluxes from continent into oceans. New studies at basin scale are thus needed to improve model calibrations. Here, a modelling approach based on JAMBECK’s statistical method and a field approach are compared in order to (i) quantify plastic fluxes in the Seine River and (ii) constrain uncertainties and their origins of the both approaches. Despite the simplicity of the statistical approach and rough extrapolations, both methods yield similar results, i.e. between 1,800 and 5,900 t/yr of plastic flowing into the Seine River. Whereas about 100 t/yr of plastic litter are removed by involved NGOs, which is a small fraction of the estimated flux. According to the MSFD (2008), actions are undertaken to quantify plastic fluxes entering the oceans. Among different methods, a better use of the data from the waste collection by NGOs should be considered. The development of a national and homogenous platform listing all the collects could be a first step in that direction.; Des estimations globales établissent des flux de plastiques entrant en mer entre 1 et 10 millions de tonnes chaque année. Mais elles sont associées à de grandes incertitudes liées à des difficultés méthodologiques pour quantifier les flux de plastiques du continent vers les océans. Travailler à l’échelle des bassins versants s’avère nécessaire afin de mieux calibrer ces approches globales. Dans cette étude, une approche de modélisation conceptuelle, basée sur l’approche statistique de JAMBECK et al., et une approche de terrain sont comparées avec pour objectif (i) de quantifier les flux de plastiques transitant en Seine et (ii) de préciser les incertitudes des deux approches et leur origine. Malgré la simplicité des approches statistiques et des techniques d’extrapolation utilisées, les deux méthodes donnent des résultats du même ordre de grandeur, c’est-à-dire entre 1800 et 5900 t/an de plastiques transitant en Seine. Les principaux acteurs de la gestion des déchets sauvages sur le fleuve ne collectent qu’environ 100 t/an de plastiques, soit une faible fraction du flux estimé. Dans le cadre de la directive cadre stratégie pour le milieu marin (DCSMM) de 2008, des actions sont mises en oeuvre afin de quantifier les flux de plastique déversés en mer. Parmi les différentes méthodes, une meilleure exploitation des données issues des collectes des associations pourrait être une aubaine avec, par exemple, la création d’une base de données nationale et homogène répertoriant les opérations de collecte.

Hybrid films, composed of a PA12 polyamide matrix filled with 5 wt% of clays were melt processed under different mixing conditions to classically obtain montmorillonite-filled microcomposites and organo-modified montmorillonite-filled nanocomposites. The change in mixing shear rates allowed to notably modulating the fragmentation level for montmorillonite and the exfoliation level for modified montmorillonite. Barrier properties to nitrogen and water were altered with a reduction in PA12 chain mobility by confinement effect and geometrical constraints. Tortuosity effects induced by fillers were also highlighted. The water permeability and diffusivity were significantly decreased with exfoliated clays, while an increase was measured with an increased water solubility in presence of clay aggregates, both counterbalanced tortuosity effects. This trend was amplified when using low shear rates. According to filler used and mixing conditions, water sorption measurement has successfully demonstrated an increase in water solubility, due to filler affinity, which was surprisingly inconsistent with the change of water permeability. The occurrence of water plasticization phenomenon was also pointed out through the non-constant diffusivity, reflecting an increased free volume with water activity. Again, a decrease in water diffusivity was unexpectedly obtained, explained by tortuosity effects and ascribed to local water retention at the vicinity of clays, which creates water aggregates in films. These findings were also confirmed by a mathematical modeling approach of sorption process, discussing about the sorbed water access.

Natural biocomposites were prepared from flax fibers and mucilage polysaccharides extracted from flax seeds, as a matrix, in two steps: impregnation and compression molding. The ribbons were preimpregnated with water plasticized mucilage. Solid mucilage (30%, w/w) was added to the ribbon impregnated with 20% mucilage, and the composite was compression molded. The solidified mucilage was homogeneous and rigid (2 GPa) with an elastic deformation of approximately 1%. The mechanical properties of the composites were in the ranges of 7–10 GPa, 300–400 MPa and 4–5% for the modulus, maximal strength and strain, respectively. The two latter parameters were larger than the ones for the fiber. The experimental values of the modulus and strength were in accordance with the values computed using the rule of mixture, which indicated a good interface between the fibers and the matrix. This was confirmed visually with scanning electron microscopy. The water sorption behavior of the composites was intermediate between the mucilage and the fiber alone.

International audience; Five blend membranes were prepared by solvent evaporation from solutions of the synthesized sulfonated polyetheretherketone (SPEEK) and sulfonated polyethersulfone-cardo (SPESc). Their ion exchange capacity and degree of sulfonation determined by acid-base titration and by thermogravimetric analysis were consistent. The blends glass transition behavior obtained by differential scanning calorimetry suggests that the two sulfonated polymers are compatible in the whole composition range. The values of the activation energy for proton transport determined by conductivity measurements on the SPEEK-based blend membranes were in the range of 13-34 kJ mol(-1), which suggest a mixed transport mechanism that involves both proton jumps on ionic sites and water of hydration and diffusion of proton-water complex in hydrophilic domains. The water vapor sorption in the membranes exhibits sigmoid-shape isotherms which were well fitted by the “new dual mode sorption” model, and the fitted parameters values were successfully used to model the change in the water permeation flux with the upstream water activity using the first Fick's diffusion equation. The fast increase in the permeation flux beyond a critical value of activity (0.5) was owing to the exponential concentration-dependent diffusion coefficient. These modelings allowed us to show a strong increase in the limit diffusion coefficient of water and a decrease in the water-diffusion plasticization coefficient with the SPEEK content in the polymer blends. (C) 2013 Elsevier Ltd. All rights reserved.