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Plastic materials are defined as including the whole of organic polymers owning plasticity. Their production increases rapidly due to their superior properties and applications in our life. Currently, the annual production of plastic is estimated at nearly 400 million tons. About 10% of the plastic produced is discharged into the seas and oceans. Microplastics (MP, less than 5 mm in size) are non-biodegradable and persistent in the environment and have the ability to accumulate in various environmental components, organisms and other human beings through the food chain. Therefore, assessing microplastic pollution becomes essential for the marine and ocean environment. This study aims to evaluate microplastic pollution in Nam Dinh seawater. Water samples were taken in summer 2020 and spring 2021 in Giao Thuy district, Nam Dinh province. Samples were treated with 30% H2O2 solution to remove organic matters and then microplastic buoyantly separated using saturated NaCl solution. MP was identified through observation under a stereo microscope (Olympus SZX2-TR300) and its nature was determined through infrared spectroscopy (µFTIR). Results show that a large level of pollution (average 6 to 8 particles/m3 and 10–14 million particles/km2) is associated with the predominant of colored fibers among MP characteristics. Most of the microplastics identified are Polypropylene in nature. Next, more research needs to be invested in this pollution problem, such as expanding the scope and research object.

Microplastics with particle size less than 5 mm are becoming a raising global environmental crisis. These pollutants were found from the poles to the equator, in continental shelves, coasts and in the oceans, moreover, they have also been identified in the water columns, sediments and even in a variety of organisms. The majority of microplastics that ended up in the oceans originate from the land. Due to their small size, they are easily accumulated in the food chain, causing harmful effects on organisms and human health. The bivalves especially caught the interest of scientific researchers because of their direct contact with microplastics through the filter-feeding habit. Therefore, it is essential to develop methods to determine the presence of microplastics in these organisms and identify their source. This study evaluated the efficiency of extracting microplastics from the tissues of green mussels (Perna viridis) using KOH 10% solution to digest and KI 50% as the separating solution. Mussel soft tissue samples were spiked five different types of microplastics: polystyrene (PS), polyvinyl chloride (PVC), polyethylene terephthalate (PET), polypropylene (PP), high-density polyethylene (HDPE) and treated with KOH 10% solution and KI 50% solution. The presence of microplastics in some green mussel species was also investigated in some mussel farming areas in Giao Thuy, Nam Dinh province, Thi Nai, Quy Nhon, Binh Dinh province and Hue city, Thua Thien Hue province. The research results showed high efficiency of microplastic extraction and recovery with the range from 76% to 97%. Microplastic concentration obtained in all mussel samples variates from 1.0 ± 0.1 particles/g to 1.7 ± 0.6 particles/g, in which fiber microplastics predominated. Microplastics in mussel samples have small sizes of < 1,000 µm and 1,000–2,000 µm, make up 74.15–82.32% and 9.76–14.71%, respectively. Purple was dominant among all mussel samples. This study proved that using KOH 10% solution and KI 50% solution to isolate microplastics is a suitable approach and can be used in monitoring studies of microplastic pollution in bivalves.

Sediments from rivers, lakes, and other continental hydrosystems constitute important sinks for microplastics but remain a poorly studied compartment (Dris et al., 2018). Microplastic spatial distribution depends both on their intrinsic properties, and also on hydro-sedimentary processes. However, the understanding of MP depositional mechanisms within sediments remains fragmentary. In the vast majority of studies, these sediments are sampled without questioning hydro-sedimentary processes which may control the abundance of MP at different spatial scales (Dekiff et al., 2014; Mani et al., 2018). In this context, 16 surface sediment samples were collected in a floodplain of the river Loire (over an 8 km² area). These samples correspond to different depositional environments with various connectivity levels and sediment compositions. After treatment of samples (organic matter digestion and densimetric separations), the quantities, types and sizes of microplastics in each sample were analysed by µFTIR (Fourier Transform Infrared Spectroscopy coupled to microscopy). In parallel, grain size distributions and total organic carbon contents were also analysed. The connectivity rate to the river flow was determined by combining sample altitudes and water level variations over the last decade. Results show MP levels ranging between 1,110 and 19,342 items/kg dw (dry weight). A substantial spatial variability is illustrated over the floodplain. Analyzes are ongoing to explain this variability regarding : (i) the connectivity rate linked with the local topography and hydrological conditons, (ii) sediment composition as a proxy of hydro-sedimentary processes, (iii) the geomorphological functionning of sampled environments, and potentially (iv) surface land cover to determine whether vegetation has a significative impact on MP abundance in these flooplain depositional environments. Also see: https://micro2022.sciencesconf.org/427190/document, In MICRO 2022, Online Atlas Edition: Plastic Pollution from MACRO to nano

The diffuse and invisible pollution caused by microplastic (MP) represents a current and global concern. While the fragmentation of plastic debris into smaller particles occurs in rivers, few data about MP effects are available on freshwater streams compared to the marine environment. Also, still too few studies combine in situ approach with the assessment of the effects of MP on organisms. Plastic-Loire project, funded by the urban community of Angers Loire Métropole, demonstrates its innovation through the complementary field/laboratory approach that aims at characterizing in situ contamination of MP in the Loire river and at evaluating MP effects on a freshwater bivalve. Firstly, MP primary characteristics (concentration, size, type, shape and colour) were determined both in sediment and in biotic matrices (polychaetes and bivalves) sampled in the Loire, longest river in France. In parallel, the ecotoxicity of MP was assessed on bivalves C. fluminea in laboratory. Organisms were exposed during 21 days to field derived MP, at 4 concentrations (0.008, 10, 100 and 500 µg.L-1). The exposure experiment was realized from an ecological realistic point of view: exposure of organisms to MP with a shape, a composition and a range of concentration similar to those found in the environment. While the condition index and the filtration capacity were not impacted by a MP exposure, the measured biochemical biomarkers involved in immune responses (CAT, GST, AchE and MDA) presented significant differences in digestive mass and gills of the organisms according to the MP concentration. Also see: https://micro2022.sciencesconf.org/426889/document, In MICRO 2022, Online Atlas Edition: Plastic Pollution from MACRO to nano

By containing high amount of plastic wastes, municipal landfills may be hot spots of secondary microplastics from fragmentation and degradation. Recent studies actually demonstrated that landfills generate microplastics that can be transferred to groundwater via landfill leachates but evaluating the threat for groundwater require more researches. The former "Prairie de Mauves" landfill, operated from 1963 to 1987 by Nantes Métropole, is a good candidate to observe the microplastic contamination of the alluvial groundwater of the Loire River. As part of the Nantes Urban Environment Observatory (ONEVU), the site is monitored since 2008. Two campaigns were therefore carried out in March and June 2022 to sample landfill leachates and groundwater. One well and 4 piezometers upstream and downstream the landfill were considered. Microplastics (¿ 25 µm) were analyzed by µFTIR imaging in transmission mode and with a 25 µm x 25 µm pixel resolution. Depending on their suspended solid loads, samples were directly filtered or followed an organic matter oxidation and a densimetric separation. Microplastics were observed in every sample with concentrations ranging from 10.3 to 106.7 particles/L. The highest concentrations were observed in the solid waste leachates. Twelve polymers were identified with polyethylene (PE) and polypropylene (PP) being the most predominant. Landfill leachates clearly impact the groundwater by increasing 2 to 5 times the microplastic concentrations from upstream to downstream of the landfill. The release of microplastics has nevertheless a high degree of temporal variability. Higher concentrations are observed in June in comparison to March. While groundwater water levels are similar, this increase can result from the difference of rain amounts between the 2 campaigns. The rainy period before the campaign carried out in June (16.2 mm) could have enhanced the microplastic migration from the landfill to the alluvial groundwater. Also see: https://micro2022.sciencesconf.org/426890/document, In MICRO 2022, Online Atlas Edition: Plastic Pollution from MACRO to nano

15e Journée scientifique de l'OSUNA, NANTES, FRANCE, 03-/06/2022 - 03/06/2022; Le projet Plasti-nium - Débris Plastiques dans le continuum terre-mer - ambitionne d'étudier la pollution plastique de la ville jusqu'à la mer et de créer une dynamique transverse et interdisciplinaire sur cette thématique au sein de la Région des Pays de la Loire. La problématique des débris plastiques et plus spécifiquement des microplastiques (taille < 5 mm) est aujourd'hui très médiatisée et trouve une caisse de résonance importante dans notre société civile. Concomitamment, la communauté scientifique démontre les impacts négatifs générés par cette pollution plastique sur les écosystèmes. Il en résulte aujourd'hui que les actions gouvernementales et autres actions locales et régionales se multiplient. La région des Pays de la Loire, dans le cadre de la stratégie « ambition marine » de 2018, vise spécifiquement la pollution plastique, et précise que des initiatives très concrètes de réduction sont déjà opérationnelles ou sur le point de l'être. Nantes Métropole, territoire reconnu « Zéro déchet, zéro gaspillage » soutient également des initiatives expérimentales, innovantes, contribuant à un territoire zéro déchet. Évaluer la mise en oeuvre de ces actions quelle que soit leur forme - de la sensibilisation à la gestion intégrée et concertée au niveau d'un territoire - constitue un enjeu. Le projet Plasti-nium vise à offrir un accompagnement scientifique de ces programmes, et de bien articuler l'acquisition des connaissances, leur transfert et les actions des politiques publiques. Cet accompagnement peut largement contribuer au rayonnement national et international de ces initiatives. Dans cette démarche, la finalité du projet Plasti-nium est de fournir un cadre de réflexion et d'expertise pour alimenter l'élaboration et la mise en oeuvre du plan régional de prévention et de gestion des déchets avec lequel la Région ambitionne d'être un territoire leader en termes de gestion des déchets.