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Microplastics provide new microbial niches in aquatic environments

Yang, Yuyi; Liu, Wenzhi; Zhang, Zulin; Grossart, Hans-Peter; Gadd, Geoffrey Michael.

Applied microbiology and biotechnology : (2020)

DOI-Link : https://doi.org/10.1007/s00253-020-10704-x

Microplastics in the biosphere are currently of great environmental concern because of their potential toxicity for aquatic biota and human health and association with pathogenic microbiota. Microplastics can occur in high abundance in all aquatic environments, including oceans, rivers and lakes. Recent findings have highlighted the role of microplastics as important vectors for microorganisms, which can form fully developed biofilms on this artificial substrate. Microplastics therefore provide new microbial niches in the aquatic environment, and the developing biofilms may significantly differ in microbial composition compared to natural free-living or particle-associated microbial populations in the surrounding water. In this article, we discuss the composition and ecological function of the microbial communities found in microplastic biofilms. The potential factors that influence the richness and diversity of such microbial microplastic communities are also evaluated. Microbe-microbe and microbe-substrate interactions in microplastic biofilms have been little studied and are not well understood. Multiomics tools together with morphological, physiological and biochemical analyses should be combined to provide a more comprehensive overview on the ecological role of microplastic biofilms. These new microbial niches have so far unknown consequences for microbial ecology and environmental processes in aquatic ecosystems. More knowledge is required on the microbial community composition of microplastic biofilms and their ecological functions in order to better evaluate consequences for the environment and animal health, including humans, especially since the worldwide abundance of microplastics is predicted to dramatically increase. Key Points• Bacteria are mainly studied in community analyses: fungi are neglected.• Microbial colonization of microplastics depends on substrate, location and time.• Community ecology is a promising approach to investigate microbial colonization.• Biodegradable plastics, and ecological roles of microplastic biofilms, need analysis.

Avis TSC : Dans cette étude, les auteurs décrivent les différents de biofilms qui colonisent les débris plastiques, leur fonctionnement et leur interaction avec le reste de l’écosystème. Dans les zones géographiques où ils sont nombreux, les effets combinés de tous ces biofilms deviennent significatifs sur la qualité des eaux. Le terme « rôle écologique » est tout à fait approprié. Il peut être négatif par la potentialisation de certains polluants, mais aussi positif, par dégradation accélérée de la matière organique dissoute, jouant ainsi le même rôle qu’une station d’épuration biologique non contrôlée.

Détection et Caractérisation

On optical sensing of surface roughness of flat and curved microplastics in water

Asamoah, Benjamin O.; Roussey, Matthieu; Peiponen, Kai-Erik.

Chemosphere: 254, 126789 (2020).

DOI-Link : https://doi.org/10.1016/j.chemosphere.2020.126789

The growth of microplastic (MP) pollution is of increasing concern and represents a global challenge. In situ detection of these small particles is difficult because of their sizes, shapes, transparency or translucency, surface texture and ambient conditions. We propose and demonstrate the use of a prototype optical sensor to detect flat, nearly flat, curved and rough MPs prepared from commercial polyethylene terephthalate (PET) plastics and PET bottles in water. The prototype measures the specular reflection of a laser radiation incident on MPs, with a photodiode, and the transmitted laser speckle pattern, with a charge-coupled device (CCD) camera. The presence of the MPs as well as the optical surface roughness are determined from the specular reflection. Additionally, the so-called speckle contrast calculated from the speckle pattern, as a promising tool, is used to rank the rough MPs according to the different average surface roughness, to approximately twice the wavelength of the probing light. The novel application of laser speckle contrast and the optical roughness estimation allows the description of MP surface roughness in water. Moreover, in combination with earlier studies, these results, therefore, pave a way for the complete and a relatively easier description of MPs properties optical and also advances our step towards the development of simple and robust optical monitoring techniques for micro and nanoplastics in open and wastewater.

Détection et Caractérisation

Optimized microplastic analysis based on size fractionation, density separation and μ-FTIR

Konechnaya, Olga; Lüchtrath, Sabine; Dsikowitzky, Larissa; Schwarzbauer, Jan.

Water science and technology : a journal of the International Association on Water Pollution Research : 81 (DocId: 4) 834–844 (2020).

DOI-Link : https://doi.org/10.2166/wst.2020.173

Microplastic particles have been recognized as global hazardous pollutants in the last few decades pointing to the importance of analyzing and monitoring microplastics, especially in soils and sediments. This study focused on a multi-step approach for microplastic analysis combining grain size fractionation, density separation and identification by μ-FTIR-spectroscopy. Eight widely used polymers (polyethylene (PE), polypropylene (PP), polyvinylchloride (PVC), polystyrol (PS), polyethylenterephthalate (PET), polymethylmethacrylate (PMMA), polyurethane (PU) and polyamide (PA)) were fractionated into four groups of grain sizes (0.1-5 mm). Thereafter, sea sand was spiked with these particles to test a ZnCl2-based density separation for the polymer types and the various grain sizes. The obtained recovery rates were close to 100% showing that ZnCl2-based density separation is suitable to separate the polymer particles from a sandy matrix. This approach was extended on three further environmental matrices and recovery rates for two of them (sandy-silty and fine-grained sediment) also provided reliable values (94-106%). Lastly, the developed multi-step approach was verified by analyzing an environmental sample (sediment from river Tiranë, Albania) characterized by smaller grain size and moderate organic matter content. Identification of two polymer types in different grain size classes verified the suitability of the developed approach for microplastic analyses on particulate matter such as soils and sediments.


Persistence of plastic debris and its colonization by bacterial communities after two decades on the abyssal seafloor

Krause, S.; Molari, M.; Gorb, E. V.; Gorb, S. N.; Kossel, E.; Haeckel, M.

Scientific reports : 10 (DocId: 1) 9484 (2020).

DOI-Link : https://doi.org/10.1038/s41598-020-66361-7

The fate of plastic debris entering the oceans is largely unconstrained. Currently, intensified research is devoted to the abiotic and microbial degradation of plastic floating near the ocean surface for an extended period of time. In contrast, the impacts of environmental conditions in the deep sea on polymer properties and rigidity are virtually unknown. Here, we present unique results of plastic items identified to have been introduced into deep-sea sediments at a water depth of 4150 m in the eastern equatorial Pacific Ocean more than two decades ago. The results, including optical, spectroscopic, physical and microbial analyses, clearly demonstrate that the bulk polymer materials show no apparent sign of physical or chemical degradation. Solely the polymer surface layers showed reduced hydrophobicity, presumably caused by microbial colonization. The bacterial community present on the plastic items differed significantly (p < 0.1%) from those of the adjacent natural environment by a dominant presence of groups requiring steep redox gradients (Mesorhizobium, Sulfurimonas) and a remarkable decrease in diversity. The establishment of chemical gradients across the polymer surfaces presumably caused these conditions. Our findings suggest that plastic is stable over extended times under deep-sea conditions and that prolonged deposition of polymer items at the seafloor may induce local oxygen depletion at the sediment-water interface.

Recyclage Matière des Déchets Plastiques

Physical Properties of Composites Manufactured with Two Wastes from Food-Processing Industry

Remadnia, Abdelghani; Goullieux, Adeline; t’Kint, Michèle Quéneudec; Dheilly, Rose-Marie.

Waste and Biomass Valorization : 11 (DocId: 6) 2995–3005 (2020).

DOI-Link : https://doi.org/10.1007/s12649-018-0525-1

The sheer amount of waste being produced nowadays by the food processing industry makes it imperative to identify alternative procedures to recycle them. This paper describes an innovative use of protein waste with consumed plastic bottles within composite materials for building applications. The aim of this study was to investigate this two wastes association on the lightening of the composites. The effect of the protein waste introduction on the physical properties of the concrete manufactured with PET aggregates in the hardened state is studied: total and surface porosity, mechanical strengths, dynamic elasticity modulus and thermal conductivity. The optimal formulation of the basic composite, with PET aggregates, is: S/C = 2.8, W/C = 0.45 and a volume percentage of PET aggregates equal to 35%. The hemoglobin powder was introduced after water in the optimal PET composite. Various H/C mass ratios were used: 0.5, 1 and 2%. The influence of the mixing time after hemoglobin addition was also studied. Relative changes in composites properties due to protein introduction are experimentally investigated. For example a decrease in mechanical strengths and in thermal conductivity was observed. The results obtained allowed the elaborated composites to be functionally classified. So they show that the simultaneous valorization of two kinds of waste of the food process industry may be technically feasible and very interesting for the environment.

Politiques et Réglementations

Plastic Debris in the Marine Environment: History and Future Challenges

Napper, Imogen Ellen; Thompson, Richard C.

Global Challenges : 4 (DocId: 6) 1900081 (2020).

DOI-Link : https://doi.org/10.1002/gch2.201900081

The success of plastic as a material has shaped the development of modern society and challenged older materials in many of their established uses. However, plastic is now a major component of litter and is extensively reported within the marine environment. Impacts from plastic debris have been identified as a major global conservation issue with implications for maritime industries, tourism, marine life, and human health. Although there are many benefits of plastic, it is clear that society's relationship and reliance on plastics needs to be addressed. Conversely, alternative materials to replace plastic items, or solutions mitigating plastic release, also need to be critiqued to make sure their properties and environmental impacts are more beneficial. This review examines the history and impact of plastics in the marine environment. Current solutions that aim to mitigate plastics accumulation in the environment and the future challenges of plastic as a material are also discussed.

Impacts de la Pollution Plastique

Primary and Secondary Plastic Particles Exhibit Limited Acute Toxicity but Chronic Effects on Daphnia magna

Xu, Elvis Genbo; Cheong, Rachel S.; Liu, Lan; Hernandez, Laura M.; Azimzada, Agil; Bayen, Stéphane; Tufenkji, Nathalie.

Environmental science & technology : 54 (DocId: 11) 6859–6868 (2020).

DOI-Link : https://doi.org/10.1021/acs.est.0c00245

Nanoplastics (NPs; <0.1 μm) are speculated to be a bigger ecological threat due to their predicted wider distribution, higher concentrations, and bioavailability. Primary NPs are manufactured to be that size, while secondary NPs originate from fragmentation of bigger debris. To date, the long-term impact of NPs in freshwater systems, particularly secondary NPs, is not well-understood. Thus, we employed a freshwater invertebrate, Daphnia magna, to investigate the chronic effects of model primary NPs, fluorescent polystyrene nanospheres (PS-NPs; 20 nm), and water leachate of weathered single-use plastics that contained micro- and nanosized particles. In experiment 1, parent Daphnia (F0) were exposed to 1 and 50 mg/L PS-NPs until the production of the neonates (F1) followed by a two-generation recovery. PS-NPs were mainly detected in the intestine and brood chamber in F0 and transferred to F1 and F2. PS-NPs significantly decreased the appendage curling and heartbeat rate in F0 and reduced reproduction in F2. In experiment 2, the plastic leachate also reduced the appendage curling rate but increased growth and reproduction. The results suggest that the acute toxicity of primary and secondary plastic particles is low even at high concentrations, but their chronic and sublethal effects should not be overlooked.

Eco-Conception des Nouveaux Matériaux Plastiques

Recent advances in polyhydroxyalkanoate production: Feedstocks, strains and process developments

Li, Mengxing; Wilkins, Mark R.

International journal of biological macromolecules : 156, 691–703 (2020).

DOI-Link : https://doi.org/10.1016/j.ijbiomac.2020.04.082

Polyhydroxyalkanoates (PHAs) have been actively studied in academia and industry for their properties comparable to petroleum-derived plastics and high biocompatibility. However, the major limitation for commercialization is their high cost. Feedstock costs, especially carbon costs, account for the majority of the final cost. Finding cheap feedstocks for PHA production and associated process development are critical for a cost-effective PHA production. In this study, waste materials from different sources, particularly lignocellulosic biomass, were proposed as suitable feedstocks for PHA production. Strains involved in the conversion of these feedstocks into PHA were reviewed. Newly isolated strains were emphasized. Related process development, including the factors that affect PHA production, fermentation modes and downstream processing, was elaborated upon.

Avis TSC : Les PHA sont des polymères qui se dégradent facilement dans la nature, y compris dans l’eau de mer. Ils sont aussi biosourcés car produits par fermentation grâce à des bactéries. Le prix de la matière est impacté principalement par celui des substrats utilisés pour la fermentation. Dans cette étude, des essais ont été effectués à partir de déchets lignocellulosiques avec succès. Cette matière est largement disponible. Elle provient principalement des activités agricoles, mais aussi de l’entretient des jardins et espaces verts.

Détection et Caractérisation

Research progress in sources, analytical methods, eco-environmental effects, and control measures of microplastics

Gong, Jian; Xie, Pei.

Chemosphere : 254, 126790 (2020).

DOI-Link : https://doi.org/10.1016/j.chemosphere.2020.126790

Microplastics are plastic particles which are widely distributed in the environment. The pollution of microplastics in environment have attracted increasing attention in recent years. This paper reviews research progress in sources, analytical methods, eco-environmental effects and control in environment, and suggests relevant countermeasures in governance and research. Microplastics mainly originate from two sources: firstly, a significant direct input of primary microplastics; second, secondary microplastics generate from the fragmentations of larger plastic materials. The analysis and identification of microplastics are critical to other researches, and related instrument methods have also been applied to the analysis and identification of microplastics. The advantages and disadvantages of microplastics analytical methods were reviewed. The eco-environmental effects of microplastics can be divided into four aspects: adsorption, biological uptake, ecotoxicological and combined pollution. Control measures need to strengthen the systematic research of microplastics pollution control and management technology system from the aspects of organizational cooperation, technological research and development, laws and regulations. In the future, a unified quantitative analysis method for microplastics should be established, and more accurate traceability analysis techniques should be developed to further explore its environmental behavior and fate. To strengthen scientific research on microplastic pollution in terrestrial, freshwater and atmospheric environments, and develop more scientific and rational control policies. This paper aims to provide a theoretical basis for the prevention and control of microplastics pollution, and also provides insights for the next step of research.

Modélisation de Pollution Plastique Marine

Setting the scene for Mediterranean litterscape management: The first basin-scale quantification and mapping of floating marine debris

Lambert, C.; Authier, M.; Dorémus, G.; Laran, S.; Panigada, S.; Spitz, J.; van Canneyt, O.; Ridoux, V.

Environmental pollution (Barking, Essex : 1987) : 263 (DocId: Pt A) 114430 (2020).

DOI-Link : https://doi.org/10.1016/j.envpol.2020.114430

Plastic pollution has become one of the biggest environmental concerns of the Anthropocene as it represents a major threat to both wildlife and human health. Garbage patches in the world's oceans are well documented, but quantitative assessments of floating debris are still lacking in some major areas. The Mediterranean Sea is one such area, despite being one of the most plastic polluted environments. We used data from the first international basin-scale survey of the Mediterranean Sea to provide the first abundance estimate of floating mega-debris (>30 cm) and map their distribution over the entire Mediterranean Sea. We estimated the total number of floating mega-debris at 2.9 million items, taking into account imperfect detection. Items larger than 30 cm represent only one fourth of the complete load of anthropogenic debris (>2 cm) in the Mediterranean, which scales up the estimate to 11.5 million floating debris. The highest densities were observed in the central Mediterranean, and the lowest in the eastern basin. This acute marine pollution might threaten to disrupt entire ecosystems through its impact on marine fauna (entanglement, ingestion, contamination), eventually impacting the tourism industry and the well-being of Mediterranean populations.

Avis TSC : Le nombre de projets pour étudier la pollution plastique en méditerranée devient très conséquent. Ils permettent une cartographie précise des zones impactées et des sources. Les auteurs proposent, en anglais, le nouveau terme de « litterscape » par analogie à « landscape ». Cet article donne une série de cartes décrivant la répartition de la pollution plastique et son évolution prédite par des modèles.

Impacts de la Pollution Plastique

Sunlight mediated cadmium release from colored microplastics containing cadmium pigment in aqueous phase

Liu, Huiting; Liu, Kun; Fu, Heyun; Ji, Rong; Qu, Xiaolei.

Environmental pollution (Barking, Essex : 1987) : 263 (DocId: Pt A) 114484 (2020).

DOI-Link : https://doi.org/10.1016/j.envpol.2020.114484

The plastics industry is the biggest consumer of cadmium pigments. Little is known about the leaching of hazardous Cd2+ from colored microplastics containing cadmium pigment in aquatic systems. Here, we reported the release of Cd2+ from different sized microplastics containing cadmium pigment in aqueous phase under simulated sunlight. The release of Cd2+ was caused by the photo-dissolution of cadmium pigment. The release kinetics is highly size-dependent. It was relatively low for microplastics with size larger than 0.85 mm but increased significantly with decreasing size for microplastics smaller than 0.85 mm. The polymer matrix was oxidized during light exposure, leading to lower average molecular weight and the formation of oxygen-containing groups. Part of the polymer matrix was degraded into soluble organic carbon under simulated sunlight, resulting in continuous Cd2+ release from the pigment particles embedded in the polymer. The polymer degradation rate is also highly size-dependent. The degradation of the polymer matrix and the release of Cd2+ were intertwined. Cadmium leaching from microplastics from a commercial product containing cadmium pigment was confirmed in water under simulated sunlight. This work suggests that the photochemical processes of inorganic pigments will lead to the release of heavy metals from colored plastic debris.

Avis TSC : Le cadmium est un des métaux lourds qui augmente le plus rapidement, année après année, dans les eaux côtières européennes. Un indicateur est en place qui mesure le cadmium dans les coquillages filtreurs de manière régulière. La première source incriminée était principalement les piles qui se retrouvaient souvent dans les déchets urbains non ou mal triés et enfouis. Les emballages plastiques constituent une autre source moins connue du grand public, mais pointée du doigt par l’INRS, en France, dans un rapport récent de 2019. On le trouve par exemple dans les fameux legos, pour lequel on peut sérieusement se poser la question comment un producteur peut mettre en conscience un produit toxique dans un objet qui sera utilisé par les enfants. L’économie circulaire commence là aussi, par le respect de ses clients !

Politiques et Réglementations

Sustainability Assessment of a Single-Use Plastics Ban

Herberz, Timo; Barlow, Claire Y.; Finkbeiner, Matthias.

Sustainability : 12 (DocId: 9) 3746 (2020).

DOI-Link : https://doi.org/10.3390/su12093746

Governments around the world are introducing single-use plastics bans to alleviate plastic marine pollution. This paper investigates whether banning single-use plastic items is an appropriate strategy to protect the environment. Product life cycle assessment was conducted for single-use plastic and single-use non-plastic alternatives. The life cycle impacts of the two product categories were compared and scaled according to EU consumption of 2016. The results show that a single-use plastics ban would decrease plastic marine pollution in the EU by 5.5% which equates to a 0.06% decrease globally. However, such a ban would increase emissions contributing to marine aquatic toxicity in the EU by 1.4%. This paper concludes that single-use items are harmful to the environment regardless of their material. Therefore, banning or imposing a premium price on single-use items in general and not only single-use plastic items is a more effective method of reducing consumption and thereby pollution. The plastics ban only leads to a small reduction of global plastic marine pollution and thus provides only a partial solution to the problem it intends to solve.

Avis TSC : Enfin des chiffres sur ces mesures très médiatico-politiques : Le bannissement des plastiques à usage unique a permis de réduire la pollution plastique marine de 0.06% au niveau mondial. Pas très motivant, et en plus cela s’accompagne d’une augmentation des rejets de polluants dans le milieu marin à hauteur de 1.4 %. Les auteurs concluent que ces mesures ne sont pas adaptées, car ce ne sont pas les plastiques à usage unique qu’il faut interdire, mais plus globalement les objets à usage unique, ceci afin de réduire la consommation globale. La solution est clairement indiquée : changer le modèle économique pour passer d’une hyperproduction à une production raisonnée frugale en ressources.

Impacts de la Pollution Plastique

The relevance of interaction of chemicals/pollutants and microplastic samples as route for transporting contaminants

Godoy, V.; Martín-Lara, M. A.; Calero, M.; Blázquez, G.

Process Safety and Environmental Protection : 138, 312–323 (2020).

DOI-Link : https://doi.org/10.1016/j.psep.2020.03.033

Microplastics have been converted a very important issue during current time. In addition, their capacity to adsorb other pollutants implies an additional problem. In this work, the potential of five types of microplastics derived from plastic waste, that include polyethylene, polyethylene terephthalate, polypropylene, polystyrene and polyvinyl chloride, to act as transporters of amoxicillin, atrazine, diuron, paracetamol, phenol and vancomycin was studied. Results suggested that microplastics, especially polyethylene, polyethylene terephthalate, polystyrene and polyvinyl chloride, revealed an essential protagonist as carriers of amoxicillin and phenol. The kinetic study showed that the sorption processes (from water to plastic) was slow and needs more than 28 days (amoxicillin) or about 21 days (phenol) to reach equilibrium. The modelling of equilibrium showed a better fit of the Langmuir model. The maximum Langmuir sorption capacities reached values between 4.03 and 8.80 mg/g for amoxicillin and between 1.25 and 2.80 mg/g for phenol. With respect to release tests, the liberation of the loaded pollutants was minor at the lower tested temperature (T =25 degrees C) and lower tested pH (pH = 2). Percentage of chemicals released increased between 1.3 and 7.9 times as the temperature increased until 40 degrees C. Similarly, the results revealed that release was greatly pH dependent. In these experiments, a singular behaviour was observed for amoxicillin at 25 degrees C, a combined effect of adsorption-release seems happen.

Impacts de la Pollution Plastique

Toxic effects of leachates from plastic pearl-farming gear on embryo-larval development in the pearl oyster Pinctada margaritifera

Gardon, Tony; Huvet, Arnaud; Paul-Pont, Ika; Cassone, Anne-Laure; Sham Koua, Manaarii; Soyez, Claude; Jezequel, Ronan; Receveur, Justine; Le Moullac, Gilles.

Water Research : 179, 115890 (2020).

DOI-Link : https://doi.org/10.1016/j.watres.2020.115890

Pearl-farming leads to significant plastic pollution in French Polynesia (FP) as the end of life of most farming gear is currently poorly managed. Plastic debris released into the aquatic environment accumulates, with potentially detrimental effects on the lagoon ecosystem and pearl oyster Pinctada margaritifera, a species of ecological, commercial and social value. Here, we tested the effects of leachates from new (N) and aged (A) plastic pearl-farming gear (spat collector and synthetic rope) obtained after 24 h and 120 h incubation, on the embryo-larval development of the pearl oyster using an in-vitro assay. Embryos were exposed for 24 h and 48 h to a negative control (0) and the leachate from 0.1, 1, 10 and 100 g of plastic. L-1. After 24 h exposure to leachate at 100 g.L-1, effects were observed on embryo development (-38% to -60% of formed larvae) and mortality (+72% to +82%). Chemical analyses of plastic gear indicated the presence of 26 compounds, consisting of organic contaminants (PAHs) and additives (mainly phthalates). Screening of leachates demonstrated that these compounds leach into the surrounding seawater with an additional detection of pesticides. Higher levels of phthalates were measured in leachates obtained from new (6.7-9.1 μg.L-1) than from aged (0.4-0.5 μg.L-1) plastics, which could be part of the explanation of the clear difference in toxicity observed after 48 h exposure at lower concentrations (0.1-10 g.L-1), associated with mortality ranging from 26 to 86% and 17-28%, respectively. Overall, this study suggests that plastic gear used in the pearl-farming industry releases significant amounts of hazardous chemicals over their lifetime, which may affect pearl oyster development that call for in-situ exploration.

Modélisation de Pollution Plastique Marine

Deposition of environmentally relevant nanoplastic models in sand during transport experiments

Pradel, Alice; Hadri, Hind El; Desmet, Cloé; Ponti, Jessica; Reynaud, Stéphanie; Grassl, Bruno; Gigault, Julien.

Chemosphere: 255, 126912 (2020).

DOI-Link : https://doi.org/10.1016/j.chemosphere.2020.126912

Nanoplastics (NPTs) are defined as colloids that originated from the unintentional degradation of plastic debris. To understand the possible risks caused by NPTs, it is crucial to determine how they are transported and where they may finally accumulate. Unfortunately, although most sources of plastic are land-based, risk assessments concerning NPTs in the terrestrial environmental system (soils, aquifers, freshwater sediments, etc.) have been largely lacking compared to studies concerning NPTs in the marine system. Furthermore, an important limitation of environmental fate studies is that the NPT models used are questionable in terms of their environmental representativeness. This study describes the fate of different NPT models in a porous media under unfavorable (repulsive) conditions, according to their physical and chemical properties: average hydrodynamic diameters (200-460 nm), composition (polystyrene with additives or primary polystyrene) and shape (spherical or polymorphic). NPTs that more closely mimic environmental NPTs present an inhomogeneous shape (i.e., deviating from a sphere) and are more deposited in a sand column by an order of magnitude. This deposition was attributed in part to physical retention, as confirmed by the straining that occurred for the larger size fractions. Additionally, different Derjaguin-Landau-Verwey-Overbeek (DLVO) models -the extended DLVO (XDLVO) and a DLVO modified by surface element integration (SEI) method-suggest that the environmentally relevant NPT models may alter its orientation to diminish repulsion from the sand surface and may find enough kinetic energy to deposit in the primary energetic minimum. These results point to the importance of choosing environmentally relevant NPT models.

Valorisation Energétique des Déchets Plastiques

Development, properties and potential applications of high-energy fuel briquettes incorporating coal dust, biowastes and post-consumer plastics

Gwenzi, Willis; Ncube, Rumbidzai S.; Rukuni, Tungamirai.

SN Applied Sciences : 2 (DocId: 6) (2020)

DOI-Link : https://doi.org/10.1007/s42452-020-2799-8

The conversion of waste to energy through briquetting has the potential for providing energy, while simultaneously reducing wastes and their environmental health risks. The current study developed and evaluated high-energy fuel briquettes from mixtures of coal dust, biowastes and postconsumer plastics. Five waste mix ratios (wt%) of coal dust (C), postconsumer plastics (P) and sawdust (S) were tested: (1) C50-40-S10, (2) C-60-P30-S10, (3) C70-P20-S10, (4) C-80-P20-S0 and (5) C-80A-P0-S20. Waste mix ratio had a significant effect (p < 0.05) on water absorption, shatter index, compressive strength and energy values, but had no effect on density. The densities (1.1-1.3 g/cm(3)) and shatter indices (94-98%) of all briquettes conformed to international standard specifications for fuel briquettes, indicating that the briquettes had acceptable handling properties. A waste mixture ratio of 50% coal dust, 40% plastics and 10% sawdust (C50-P40-S10) produced a briquette with the best overall combination of handling and energy properties. The high-energy briquettes had calorific values of 26.5-33.8 MJ/kg, which were significantly higher than or comparable to the maximum values reported for high-energy coal (27 MJ/kg), while the compressive strength was 0.7 MPa. Potential applications of the briquettes include (1) household and institutional heating and cooking and (2) industrial heating in kilns, furnaces, smelters, curing and drying of crops (e.g., tobacco barns. Further work is required to address the following: (1) evaluation of the detailed physicochemical, combustion and emission properties, (2) optimization of the briquetting process, (3) cost estimation of the briquettes relative to existing competing solid fuels and (4) comparative performance evaluation of the briquettes versus conventional solid fuels in the various applications.

Avis TSC : Les polymères en plastiques sont riches en carbone organique au même titre que la cellulose ou la lignine du bois. Ce sont donc des matériaux ayant aussi un pouvoir calorifique élevé lorsqu’ils sont brûlés. D’où l’idée des auteurs de cette étude de transformer les débris de plastiques en briquettes condensées, mélangés avec de la sciure de bois et de la poussière de charbon, afin d’en faire un combustible pratique à utiliser. Le mélange le plus performant est constitué de 50% de poussière de charbon, 40% de débris plastiques et 10% de sciure de bois. Les gaz émis lors de la combustion n’ont pas été analysés, ni le modèle économique. La qualité des émissions gazeuses dépendra beaucoup des types de plastique et des additifs. Le PVC, par exemple émettra beaucoup de chlore. Si l’innocuité des émissions est gérée, cette approche « low cost » a le mérite de placer la fin de vie du plastique dans un circuit court qui produira plus d’énergie qu’il n’en consomme comparativement à son recyclage. Une analyse de cycle de vie serait à construire sur cette idée.

Détection et Caractérisation

Environmental status of (micro)plastics contamination in Portugal

Prata, Joana C.; da Costa, João P.; Lopes, Isabel; Duarte, Armando C.; Rocha-Santos, Teresa.

Ecotoxicology and environmental safety: 200, 110753 (2020).

DOI-Link : https://doi.org/10.1016/j.ecoenv.2020.110753

Plastics and microplastics are ubiquitous contaminants in aquatic ecosystems. This critical review is the first attempt at analyzing sources, concentration, impacts and solutions of (micro)plastic litter in Portugal based on all currently available literature. We found that, besides sea-based sources (e.g. shipping, fishing), 5717 t of mismanaged waste and 4.1 trillion microplastics from wastewater, mostly from untreated wastewater, are released to the environment every year. The highest concentrations are found in the North, Center and Lisbon regions, mostly comprised of consumer products, fishing gear and microplastics (<5 mm), especially fragments and pellets. This contamination has resulted in ingestion of plastics by organisms, including mussels, fishes, birds and turtles. Thus, every Portuguese citizen may consume 1440 microplastics a year based on the consumption of mollusks. Awareness campaigns, improvements in waste management and reductions in the release of untreated wastewater are recommended measures to reduce plastic pollution in Portugal.

Impacts de la Pollution Plastique

Evidence of ingested plastics in stranded loggerhead sea turtles along the Greek coastline, East Mediterranean Sea

Digka, Nikoletta; Bray, Laura; Tsangaris, Catherine; Andreanidou, Konstantina; Kasimati, Eirini; Kofidou, Evangelia; Komnenou, Anastasia; Kaberi, Helen.

Environmental pollution (Barking, Essex: 1987) : 263 (DocId: Pt A) 114596 (2020).

DOI-Link : https://doi.org/10.1016/j.envpol.2020.114596

Plastic debris has become a major threat to the marine environment and wildlife. Sea turtles are particularly vulnerable, and are known to ingest plastic debris globally; however, information from Greek waters is still absent. In this study, 36 stranded dead loggerhead turtles (Caretta caretta) were collected from the Greek coastline area, and their gastrointestinal content was analysed for ingested plastic debris. Twenty-six individuals (72%) were found to have ingested plastic, with an average of 7.94 ± 3.85 (SE) plastic items per turtle. In total, 286 plastic items were counted and categorised by size, shape, colour, and polymer type. Fourier Transform Infrared Spectrometry revealed that polypropylene and polyethylene were the dominant polymer plastic types found. Results indicated a variation in plastic ingestion amongst life stages of the loggerhead specimens. This study provides evidence of plastic ingestion by loggerhead turtles in Greek waters.

Impacts de la Pollution Plastique

Experimental ingestion of fluorescent microplastics by pacific oysters, Crassostrea gigas, and their effects on the behaviour and development at early stages

Bringer, Arno; Cachot, Jérôme; Prunier, Grégoire; Dubillot, Emmanuel; Clérandeau, Christelle; Hélène, Thomas.

Chemosphere: 254, 126793 (2020).

DOI-Link : https://doi.org/10.1016/j.chemosphere.2020.126793

Plastics are persistent synthetic polymers that accumulate as waste in the marine environment. Microplastics (MPs, <5 mm) can be found either as microbeads in body care and some industrial products or as plastic debris through degradation. Plastic microbeads (1-5 μm, fluorescent, Cospheric) were used to characterise the MP ingestion and determine their potential harmful effects on both the swimming behaviour and development of oyster D-larvae (Crassostrea gigas). For 24 h, embryos were first exposed to MPs at a temperature of 24 °C. In addition, 3 day-old D-larvae were exposed to the same temperature for 1, 3 and 5 h. Three concentrations of MPs were used: 0.1, 1 and 10 mg MP. L-1. After a 24-h period of embryonic exposure, we noted that MP agglomerates were stuck to the D-larvae coat and locomotor eyelashes. We also observed a significant increase in severe malformations and developmental arrests for larvae exposed to MPs ranging from 1 mg MP. L-1. In terms of swimming behaviour, the maximum speed recorded was lower for larvae exposed at 0.1 and 1 mg MP. L-1. After an acute exposure to MPs, particles were found in the digestive tract of 3 dpf (days post fertilisation) D-larvae. After 1-h exposure, the concentrations tested (0.1, 1 and 10 mg MP. L-1) resulted in respectively 38%, 86% and 98%. The larvae swimming behaviour was recorded and analysed. Unlike the results observed at the embryo-larval stage, 3-dpf larvae showed significant impacts with no dose-response effect.

Eco-Conception des Nouveaux Matériaux Plastiques

Experimental Research on the Physical and Mechanical Properties of Concrete with Recycled Plastic Aggregates

Wu, Haikuan; Liu, Changwu; Shi, Song; Chen, Kangliang.

Journal of Renewable Materials: 8 (DocId: 7) 727–738 (2020).

DOI-Link : https://doi.org/10.32604/jrm.2020.09589

In order to study the effect of recycled plastic particles on the physical and mechanical properties of concrete, recycled plastic concrete with 0, 3%, 5% and 7% content (by weight) was designed. The compressive strength, splitting tensile strength and the change of mass caused by water absorption during curing were measured. The results show that the strength of concrete is increased by adding recycled plastic into concrete. Among them, the compressive strength and the splitting tensile strength of concrete is the best when the plastic content is 5%. With the increase of plastic content, the development speed of early strength slows down. Silane coupling agent plays a positive role in the strength of recycled plastic concrete. The water absorption saturation of concrete has been basically completed in the early stage. The addition of silane coupling agent makes the porosity of concrete reduce and the water absorption of concrete become poor. By summing up the physical and mechanical properties of recycled plastic concrete, it could be found that the addition of recycled plastic was effective for the modification of concrete materials. Under the control of the amount of recycled plastic, the strength of concrete with recycled plastic aggregates can meet the engineering requirements.

Avis TSC : Les études pour intégrer les débris plastiques dans les ciments se multiplient. Celle-ci démontre que sous certaines conditions de qualité et de quantité, les ciments sont conformes aux normes techniques. Compte tenu de la production annuelle de ciment à travers le monde, estimée à 3,3 milliards de T, l’incorporation de 5% de débris plastiques permettrait au mieux d’en utiliser 165 MT/an. Sachant qu’actuellement 273 MT de déchets plastiques sont produits chaque année, que tous les ciments ne peuvent pas intégrer du plastique, et que la production de plastique va doubler d’ici 10 ans, cette solution n’est qu’une possibilité de recyclage qui ne résoudra pas tout, à moins d’augmenter considérablement l’utilisation des ciments. De plus la production de microplastiques lors de l’érosion naturelle des ciments et la gestion de leur fin de vie sont deux points faibles de cette voie de recyclage dont la valeur ajoutée réside essentiellement à retarder la fin de vie des débris plastiques et donc leur effet sur le climat par émission de CO2. Les générations futures apprécieront le cadeau.

Impacts de la Pollution Plastique

First report on the presence of small microplastics (≤ 3 μm) in tissue of the commercial fish Serranus scriba (Linnaeus. 1758) from Tunisian coasts and associated cellular alterations

Zitouni, Nesrine; Bousserrhine, Noureddine; Belbekhouche, Sabrina; Missawi, Omayma; Alphonse, Vanessa; Boughatass, Iteb; Banni, Mohamed.

Environmental pollution (Barking, Essex: 1987): 263 (DocId: Pt A) 114576 (2020).

DOI-Link : https://doi.org/10.1016/j.envpol.2020.114576

There is limited research on the ingestion of microplastic particles (MPs) by fish from the southern part of the Mediterranean Sea. This study provides the occurrence of small MPs (≤3 μm) in the gastrointestinal tract and muscle of adult benthopelagic fish Serranus scriba (L.1758), caught along Tunisian coasts. MPs were extracted from selected tissues using a potassium hydroxide digestion method (KOH 10%) and then quantified, and their chemical structure was characterized through Raman microspectroscopy. The results highlighted that MPs were present in all samples. The average abundance of MPs per gram of fish tissue identified through successive filters of 3 μm, 1.2 μm, and 0.45 μm differed significantly among the sites. The properties of the MPs extracted indicated that polyethylene-vinyl-acetate (PEVA: 33.45%), high density polyethylene (HD-PE: 17.33%), and fragments were the most abundant plastic types and shape found, respectively. Among those, most MPs were found at a size class of 3-1.2 μm (∼60%), especially in the muscle, suggesting a high transfer of MPs into the human diet. Our field work also aimed to explore the effects observed in the gastrointestinal tract with a battery of biomarkers assessing oxidative stress and neurotoxicity. The preliminary results of this study showed the existence of a link between small MPs, sites, and their associated urban activities and induced oxidative stress. However, more detailed studies are required to evaluate the transfer of MPs into tissues and the potential impacts of this transfer on human health.

Avis TSC : La présence des microplastiques dans le système digestif des poissons est de plus en plus documentée, car ces derniers ingèrent facilement les microparticules qui polluent les eaux. Le mécanisme n’est pas encore connu, mai sil semblerait que ces microplastiques se retrouvent aussi dans les muscles des poissons. Cette étude vient de le démonter dans la perche de mer le long des côtes Tunisiennes. Ceci implique un risque d’ingestion potentiel par les consommateurs beaucoup plus élevé que prévu.

Eco-Conception des Nouveaux Matériaux Plastiques

Identification of Commercial Oxo-Biodegradable Plastics: Study of UV Induced Degradation in an Effort to Combat Plastic Waste Accumulation.

Antelava, Ana; Constantinou, Achilleas; Bumajdad, Ali; Manos, George; Dewil, Raf; Al-Salem, S. M.

Journal of Polymers and the Environment :

DOI-Link : https://doi.org/10.1007/s10924-020-01776-x

End of life single-use items such as carrier bags constitute a large proportion of the litter found in marine and terrestrial environments. The main objective of the current work was to investigate the response of an oxo-biodegradable commercial plastic film product to photo-degradation using accelerated weathering, verifying the claim of its biodegradability and suitability as an eco-friendly product. This study is also geared towards the appropriateness of such products to reduce plastic waste accumulation in urban environments. The film samples were exposed to weathering as a means to determine the impact of UV induced oxo-biodegradation. Haze (%), light transmission (%) and the total change in colour (Delta E) were measured as indicators to the degradation profile of the polymeric materials, in addition to tensile pull mechanical properties and thermal stability. The melting peak indicates the melting point (T-m) of the polymer and with exposure to weathering it showed a slight decrease from 105 to 102 degrees C indicating that biodegradation mechanisms were triggered to a certain extent. The reduction in strain at rupture was also indicative for a loss in crystalline structure, coupled with Young's modulus increase throughout the weathering exposure tests. Therefore, the material studied could be a candidate to mitigate the accumulation of plastic waste in open environments based on the results of this study whilst regulating controlled substances.

Avis TSC : Pour rendre les plastiques « biodégradables », avec beaucoup de guillemets, la première approche des producteurs a été d’ajouter aux molécules de polymères classiques, des additifs qui favorisent leur oxydation naturelle. Effectivement, la première étape de fragilisation et de fragmentation des films plastiques se réalise bien, mais la dégradation s’arrête à ce stade. Finalement, ils forment de grandes quantités de microplastiques. C’est pourquoi ils sont interdits dans de nombreux pays et l’étiquette biodégradable ne peut plus leur être attribuée. Il semblerait que cette réglementation ne s’applique pas au Koweit, pays d’origine des auteurs de cette étude. Ils ont démontré que les polymères oxo-dégradables se fragilisaient bien et se fragmentaient, mais pas qu’ils se dégradaient… CQFD.

Détection et Caractérisation

Microlitter pollution in coastal sediments of the northern Tyrrhenian Sea, Italy: microplastics and fly-ash occurrence and distribution

Piazzolla, Daniele; Cafaro, Valentina; Lucia, Giuseppe Andrea de; Mancini, Emanuele; Scanu, Sergio; Bonamano, Simone; Piermattei, Viviana; Vianello, Alvise; Della Ventura, Giancarlo; Marcelli, Marco.

Estuarine, Coastal and Shelf Science: 241, 106819 (2020).

DOI-Link : https://doi.org/10.1016/j.ecss.2020.106819

Marine litter is included in the eleven descriptors of the Marine Strategy Framework Directive (MSFD) necessary for the assessment of the marine environmental status. In this work, we studied the abundance and typology of microparticles extracted from coastal sediments in the northern Latium area, Tyrrhenian sea, Italy. Particles having different shapes (fragments, microspheres, and filaments), size and color were recognized to belong to two typologies, i.e. micmplastics (MPs) and aluminum silicate microspheres (ASMs) interpreted as fly-ash produced by fossil fuel combustion. MPs abundances were comparable with data from the literature related to the same depositional contexts in the Mediterranean Sea and elsewhere, while ASMs contributed 32% to the total average microlitter abundance in this coastal area. MPs and ASMs distribution could reflect the contributions of the land-based sources and the hydrodynamic features of the study area.

Détection et Caractérisation

Microplastic pollution in intertidal sediments along the coastline of China

Wang, Qing; Shan, Encui; Zhang, Bin; Teng, Jia; Di Wu; Yang, Xin; Zhang, Chen; Zhang, Wenjing; Sun, Xiyan; Zhao, Jianmin.

Environmental pollution (Barking, Essex : 1987) : 263 (DocId: Pt A) 114428 (2020).

DOI-Link : https://doi.org/10.1016/j.envpol.2020.114428

Research on microplastic (MP) pollution in the marine environment has received widespread attention in recent years. To assess the degree of MP contamination in the intertidal zone of China, the abundance, shape, particle size and composition of MPs in sediment were investigated in this study. Sediment samples were collected from 13 stations along the coast of China. The density separation method was employed to isolate MPs from sediment and the polymer types of the MPs were determined by Fourier transform infrared microspectroscopy. Our study demonstrated that MP pollution was widespread in the 13 intertidal stations. The average abundance of MPs was 309 ± 81 items/kg dry weight. Fiber accounted for 71.5% of the isolated MPs, and the particles of less than 500 μm accounted for the highest proportion (35.0%). A total of 12 polymers were identified; the main types were rayon (RY), polypropylene (PP), polyethylene terephthalate (PET) and polyethylene (PE). The shape and chemical composition of the MPs from the intertidal sediments of South and North China were different. In South China, MP fragments were more extensive, and PP was a more important component. In contrast, the intertidal sediments of North China contained more MP fibers with the majority being RY, indicating that the major source of MPs in the intertidal zone of North China may be domestic sewage. Additionally, the abundance of MPs in the intertidal sediments of the Pearl River and Jiulong River estuaries was higher than at other sites. A Spearman's correlation analysis showed that there was no correlation between MP abundance and sediment grain size or organic matter content. Our study highlights the ubiquitous distribution of MPs in the sediment along the coast of China and provides valuable information for risk assessment and source control of MP pollution in China's intertidal zone.

Détection et Caractérisation

Microplastics in Freshwater Biota: A Critical Review of Isolation, Characterization, and Assessment Methods

O'Connor, James D.; Mahon, Anne Marie; Ramsperger, Anja F. R. M.; Trotter, Benjamin; Redondo‐Hasselerharm, Paula E.; Koelmans, Albert A.; Lally, Heather T.; Murphy, Sinéad.

Global Challenges : 4 (DocId: 6) 1800118 (2020).

DOI-Link : https://doi.org/10.1002/gch2.201800118

Freshwater systems provide key pathways for microplastic (MP) pollution, and although existing studies have demonstrated the susceptibility of freshwater biota to ingestion, translocation, and trophic transfer, specific challenges pertaining to methodological standardization remain largely unresolved, particularly with respect to isolating, characterizing, and assessing MPs. Here, a critical review is performed outlining the challenges and limitations currently faced by freshwater MP researchers, which may well apply across the MP research spectrum. Recommendations are provided for methodological standardization, particularly in MP characterization, quality assurance, and quality control (QA/QC) procedures as well as reporting. Considerations for the assessment of MPs in freshwater biota as a means of improving comparisons between studies are discussed. Technological advancements, including the improvement of laboratory infrastructure for identifying MPs within the smaller size range as well as methodological standardization are essential in providing policy makers with tools and measures necessary to determine the distribution of MPs within freshwater ecosystems, while also allowing for comparability and providing compliance for future monitoring requirements.

Impacts de la Pollution Plastique

A closer look at anthropogenic fiber ingestion in Aristeus antennatus in the NW Mediterranean Sea: Differences among years and locations and impact on health condition

Carreras-Colom, Ester; Constenla, María; Soler-Membrives, Anna; Cartes, Joan E.; Baeza, Mireia; Carrassón, Maite.

Environmental Pollution: 263, 114567, (2020).

DOI-Link : DOI-Link: https://doi.org/10.1016/j.envpol.2020.114567

Marine litter is one of the most concerning threats for marine wildlife especially regarding plastics and their micro-sized forms, widely known as microplastics. The present study evaluates mesoscale spatial (230 km, Catalan coast) and temporal (2007 vs 2017-2018, Barcelona area) differences on the ingestion of anthropogenic fibers in the deep-sea shrimp Aristeus antennatus in the NW Mediterranean Sea and its relation with shrimp's health condition. Synthetic fibers with lengths ranging between 0.16 and 37.9 mm were found in both stomach (where sometimes they were tangled up in balls) and intestine contents. The percentage of fiber occurrence was >65% at each sampling point. Tangled balls of fibers observed in stomach contents exhibited a wide range of sizes (up to a diameter of 1 cm) and were usually composed of fibers of different polymers, sizes and colors. Differences between locations (2018) were found, with greater fiber loads towards the south during spring and a great variability in summer, as shrimps caught off Barcelona showed a nearly thirty-times higher fiber load compared to shrimps from other localities. Highest concentrations were more likely to be related to major sources of fibers and currents in the area. Fiber load in shrimps from 2007 was comparable to that of shrimps captured in 2017 and 2018 (spring) yet a shift in the proportion of acrylic and polyester polymers was detected. No consistent effect on shrimp's health condition was found, with only a significant negative correlation found between gonadosomatic index and fibers for those shrimps with the highest values of fiber load (caught off Barcelona, summer 2018). Our findings contribute to the knowledge on plastic pollution for the NW Mediterranean Sea and highlight the potential use of this species as a sentinel species for plastic fiber contamination.

Avis TSC : Les effets de la pollution par les microplastiques présentent de multiples facettes. Les auteurs ont montré dans cette étude que les microparticules ont peu d’effet sur la santé des crevettes. Toutefois, ils ont observé un impact sur les glandes génitales dont l’activité cellulaire a été modifiée. L’origine de cet effet est à rechercher dans les résultats des études en cours sur les perturbateurs endocriniens. En effet, plusieurs familles d’additifs sont suspectées d’avoir ce genre d’effet et certaines ont été interdites. Malheureusement, la durée de vie des matières plastiques est telle que leur persistance dans le milieu naturel est très longue et donc la diffusion de ces molécules d’additifs perdure pendant des années après l’interdiction. La pollution par les microplastiques a le mérite de nous souligner toute l’étendue du problème qui au final va impacter notre santé en même temps que celle des écosystèmes.

Impacts de la Pollution Plastique

A review on sources and health impacts of bisphenol A

Abraham, Anna; Chakraborty, Paromita.

Reviews on environmental health: 35 (DocId: 2) 201–210 (2020).

DOI-Link : https://doi.org/10.1515/reveh-2019-0034

Bisphenol-A (BPA) is a synthetic chemical used in the manufacturing of polycarbonates and epoxy resins. This paper is a review of studies reporting the occurrences and concentrations of BPA in the environment and associated impact on human health. Studies have found that at high temperature conditions such as open burning of dumped waste in developing nations can relocate BPA from plastic waste into the environment. BPA is a proven endocrine disruptor capable of mimicking or blocking the receptors and altering hormone concentrations and its metabolism. Even though it is consumed in a low dose, it can stimulate cellular responses and affect body functions. Biomonitoring studies show that human and animal exposure to BPA is rapid and continuous. In-depth studies are needed to understand the fate of these compounds particularly in the developing nations and the associated adverse health impacts of BPA due to prolonged exposure.

Avis TSC : Dans notre avis sur un article précédent, nous faisions le rapprochement entre les additifs perturbateurs endocriniens et les effets des microplastiques ingérés par les crevettes, sur leurs glandes génitales. Ici, les auteurs font un état des lieux des connaissances sur le bisphénol A et ses impacts sur la santé. C’est un additif très présent dans les formulations des polycarbonates et des résines Epoxy. Ces dernières sont très utilisées comme revêtement intérieur des boîtes de conserve. Depuis 2013, le BPA est interdit en France et en Europe dans les formulations pour cette application. En effet, des études ont montré que sa diffusion en dehors de la résine était accentuée par la température, ce qui pose un problème lors de la cuisson ou de la stérilisation des conserves. Une accumulation chronique des doses a été observée chez les consommateurs, mais des effets toxiques à court terme sont aussi possibles. Ceci souligne l’importance de bien considérer la catégorie « pour usage alimentaire » dans les plastiques entrant en contact avec nos aliments au quotidien et donc de ne plus utiliser les anciens objets en plastique pour cet usage. Malheureusement, ces derniers sont encore très présents dans l’environnement et continuent donc à diffuser leur BPA dans les écosystèmes.

Impacts de la Pollution Plastique

Abundance and distribution of small microplastics (≤ 3 μm) in sediments and seaworms from the Southern Mediterranean coasts and characterisation of their potential harmful effects

Missawi, Omayma; Bousserrhine, Noureddine; Belbekhouche, Sabrina; Zitouni, Nesrine; Alphonse, Vanessa; Boughattas, Iteb; Banni, Mohamed.

Environmental Pollution: 263, 114634 (2020).

DOI-Link : https://doi.org/10.1016/j.envpol.2020.114634

Microplastics (MPs) are an uncontrolled contaminant affecting marine ecosystems. Studying their undesirable effects has been an attractive field for scientists in recent years. This study is the first to investigate the uptake and distribution of small microplastics (<= 3 mu m) from several sites in the Southern Mediterranean coasts. This work primarilyaims to provide a qualitative and quantitative analysis of microplastics in sediments as well as in the seaworms (Hediste diversicolor) from eight sites from the Tunisian coasts using Fourier transform infrared spectroscopy and Raman microspectroscopy. The second aim is to evaluate the potential toxic effects of environmental microplastics using a set of biomarkers such as Catalase, Glutathione-S-Transferase, Malondialdehyde and Acetylcholinesterase. Our findings showed that microplastics (1 mm-1.2 µm) were present in all sediments with its abundance ranging from 129 to 606 items /kg. Microplastic accumulation in seaworms (3 µm-0.22 µm) was 0.5-3.7 items/g. The predominant polymer was polyethylene. Results also revealed a significant variation among sites in the parameters associated with oxidative stress. Thus, size abundance of microplastics in seaworms was mainly correlated with oxidative stress biomarkers. Our data should be carefully considered in view of the microplastic presence with several types and sizes in Tunisian coastal sites, their potential toxic effects, and their transfer into food web.

Impacts de la Pollution Plastique

Adverse physiological and molecular level effects of polystyrene microplastics on freshwater microalgae

Xiao, Yao; Jiang, Xiaofeng; Liao, Yuanchen; Zhao, Weigao; Zhao, Peng; Li, Mei.

Chemosphere : 255, 126914 (2020).

DOI-Link : https://doi.org/10.1016/j.chemosphere.2020.126914

Microplastics have aroused widespread concern because of their adverse effects on aquatic organisms. However, the underlying toxicity mechanisms have not been examined in detail. This study investigated the interactions between polystyrene microplastics (PS-MPs) and the model freshwater microalgae Euglena gracilis. The results of transmission electron microscopy showed that the vacuoles of microalgae were induced after 24 h exposure to 1 mg/L PS-MPs (5 μm and 0.1 μm). Furthermore, PS-MPs significantly (p < 0.05) reduced pigment contents. Moreover, superoxide dismutase activities were significantly (p < 0.05) induced in all PS-MPs treated groups. Peroxidase activities were also significantly (p < 0.05) affected by two sizes of PS-MPs (5 μm and 0.1 μm), indicating that oxidative stress was induced after exposure to PS-MPs. At the molecular level, PS-MPs dysregulated the expression of genes involved in cellular processes, genetic information processing, organismal systems, and metabolisms. The KCS gene and the CTR1 gene may be key pathways to induce adverse effects on the E. gracilis after exposure to 5 μm PS-MPs. These findings will help to elucidate the underlying molecular mechanism of microplastics toxicity on freshwater organisms.

Avis TSC : Cette étude montre que les effets des microplastiques sur les organismes vivants ne se limitent pas à ceux capables de les ingérer. Les microalgues de type Euglènes ne se nourrissent pas de microparticules mais utilisent la photosynthèse. Malgré cela, ces auteurs ont démontré que l’ajout de microbilles de polystyrène peut perturber le métabolisme de ces microalgues. Le mécanisme semble être lié à une dérégulation de l’expression des gènes et à une réponse au stress oxydatif. Les molécules à l’origine de ces effets n’ont pas été identifiées. Elles sont présentes dans les formulations des PS utilisés dans l’expérience.

Modélisation de Pollution Plastique Marine

Beaches of the Azores archipelago as transitory repositories for small plastic fragments floating in the North-East Atlantic

Pham, Christopher K.; Pereira, João M.; Frias, João P. G. L.; Ríos, Noelia; Carriço, Rita; Juliano, Manuela; Rodríguez, Yasmina.

Environmental pollution (Barking, Essex: 1987) : 263 (DocId: Pt A) 114494 (2020).

DOI-Link : https://doi.org/10.1016/j.envpol.2020.114494

Plastic pollution is among the most pervasive stressors currently influencing the marine environment and affecting even the most remote areas. To date, there are still fundamental gaps in our understanding of the major pathways and fate of plastic debris in the oceans. Here we show that oceanic insular environments are important transitory repositories of small plastic items floating in the open ocean. Monthly monitoring of seven beaches over a three-year period demonstrate that beaches of the Azores islands with particular characteristics can capture significant quantities of fragments between 2 and 5 mm in length. The beach with the highest plastic loading rates was found to occasionally accumulate densities exceeding 15,000 fragments m-2 on part of the backshore. However, a large portion of these fragments can be rapidly washed back into the marine environment. Detailed characterization of those plastic items revealed the typology and size distribution to be similar throughout the seven beaches and through the 33 months surveyed, suggesting a same and unique source. Our results show that these oceanic islands of the North-East Atlantic are under pressure of high quantities of fragmented plastic debris that probably entered the ocean many years ago.

Avis TSC : La pollution plastique ne connaît pas de frontière. Cet exemple montre bien comment un archipel d’îles, aux Açores, se retrouve impacté par une pollution qui ne provient pas de son activité nationale. Et il ne s’agit pas d’un phénomène ponctuel, car un suivi sur 33 mois et sur 7 plages a montré que les types de plastiques étaient identiques et provenaient très probablement de la même source.

Impacts de la Pollution Plastique

Behavior of tetracycline and polystyrene nanoparticles in estuaries and their joint toxicity on marine microalgae Skeletonema costatum

Feng, Li-Juan; Shi, Yi; Li, Xiang-Yu; Sun, Xiao-Dong; Xiao, Fu; Sun, Jia-Wen; Wang, Yue; Liu, Xiao-Yun; Wang, Shu-Guang; Yuan, Xian-Zheng.

Environmental pollution (Barking, Essex : 1987) : 263 (DocId: Pt A) 114453 (2020).

DOI-Link : https://doi.org/10.1016/j.envpol.2020.114453

Polystyrene nanoplastics (PS NPs), which are newly emerging as particulate pollutants, are one of the most abundant plastic types in marine debris. Although there has been extensive research on microplastics, the sorption behavior of PS NPs in surface waters remains unknown. In addition, in the previous joint toxicity studies, the concentration of organic pollutant in the joint system was based on the EC50 of this pollutant, rather than the actually amount of this pollutant adsorbed on nanoplastics (NPs). In this study, the sorption behavior of PS NPs with different surface charges in the surface water of estuaries and joint toxicity of that absorbed tetracycline antibiotic in equilibrium were investigated for the first time. Because of the electrostatic repulsion, salting-out effect, and partition function, the sorption capacity of tetracycline antibiotic by differently charged PS NPs was enhanced with increasing salinity. The biological effects of exposure to tetracycline-saturated PS NPs were complicated, which can be attributed to the surface characteristics of mixtures such as hydrophobicity and charges. Thus, the role of NPs in the natural environment as a carrier of antibiotics may provide an alternative for antibiotic inputs from inland water to coastal marine water, which would not only change the environmental fate and ecotoxicology of antibiotics and NPs, but also pose challenges to the safety of coastal aquaculture and marine ecosystem.

Avis TSC : Les particules de plastiques apportent leur pollution propre associée à la chimie de leurs formulations, mais elles peuvent aussi jouer le rôle d’adsorbants qui vont fixer des métaux lourds ou des molécules organiques polluantes. Le cas présenté ici concerne l’adsorption des antibiotiques de type tetracycline sur des nanoparticules de plastiques en phase aqueuse. Ce phénomène est bien présent dans l’eau douce et il est accentué quand la salinité augmente. C’est-à-dire que les particules auront plus d’affinité pour l’antibiotique qui se fixera en plus grande quantité. C’est une nouvelle voie qui vient d’être mise en évidence pour la diffusion des molécules antibiotiques polluantes dans l’environnement marin. L’utilisation massive de ces molécules comme facteur de croissance en alimentation animale et comme médicament en santé humaine rend leur présence très préoccupante dans les eaux de surface et donc maintenant dans les eaux marines côtières.

Biodégradation des Débris Plastiques

Biodegradation of Polystyrene by Pseudomonas sp. Isolated from the Gut of Superworms (Larvae of Zophobas atratus)

Kim, Hong Rae; Lee, Hyun Min; Yu, Hee Cheol; Jeon, Eunbeen; Lee, Sukkyoo; Li, Jiaojie; Kim, Dae-Hwan.

Environmental science & technology: 54 (DocId: 11) 6987–6996 (2020).

DOI-Link : https://doi.org/10.1021/acs.est.0c01495

Recently, various attempts have been made to solve plastic waste problems, such as development of biodegradation without producing pollution. Polystyrene (PS) is the fifth most used plastic in many industries; therefore, degrading PS becomes a critical global issue. Here, we reported Pseudomonas aeruginosa strain DSM 50071, initially isolated from the gut of the superworms, Zophobas atratus, and the PS degradation by Pseudomonas sp. DSM 50071. We examined PS degradation using electronic microscopy and measured changes in atomic composition and contact angles with water droplets on the PS surface that represents a chemical change from hydrophobicity to hydrophilicity. We have further examined chemical structural changes using X-ray photoelectron spectroscopy, Fourier-transform-infrared spectroscopy, and nuclear magnetic resonance (NMR) to confirm the formation of carbonyl groups (C═O) in the oxidation pathway during PS biodegradation. In reverse transcription quantitative polymerase chain reaction analysis, the gene expression level of serine hydrolase (SH) in Pseudomonas sp. DSM 50071 was highly increased during PS degradation, and the enzyme-mediated biodegradation of PS was further confirmed by the SH inhibitor treatment test. Thus, the significance of these findings goes beyond the discovery of a novel function of Pseudomonas sp. DSM 50071 in the gut of superworms, highlighting a potential solution for PS biodegradation.

Avis TSC : Les auteurs de cette étude ont cherché à comprendre comment certains vers étaient capables de dégrader le polystyrène. Ils ont trouvé leur système digestif une nouvelle souche de bactérie de type Pseudomonas aeruginosa produisant une enzyme à l’origine de la biodégradation. Cette découverte ouvre la voie à un traitement des déchets de PS en bioréacteurs ou par catalyse enzymatique.


Biodiversity of Microorganisms Colonizing the Surface of Polystyrene Samples Exposed to Different Aqueous Environments

Tourova, Tatyana; Sokolova, Diyana; Nazina, Tamara; Grouzdev, Denis; Kurshev, Eugeni; Laptev, Anatoly.

Sustainability : 12 (DocId: 9) 3624 (2020).

DOI-Link : https://doi.org/10.3390/su12093624

The contamination of marine and freshwater ecosystems with the items from thermoplastics, including polystyrene (PS), necessitates the search for efficient microbial degraders of these polymers. In the present study, the composition of prokaryotes in biofilms formed on PS samples incubated in seawater and the industrial water of a petrochemical plant were investigated. Using a high-throughput sequencing of the V3-V4 region of the 16S rRNA gene, the predominance of Alphaproteobacteria (Blastomonas), Bacteroidetes (Chryseolinea), and Gammaproteobacteria (Arenimonas and Pseudomonas) in the biofilms on PS samples exposed to industrial water was revealed. Alphaproteobacteria (Erythrobacter) predominated on seawater-incubated PS samples. The local degradation of the PS samples was confirmed by scanning microscopy. The PS-colonizing microbial communities in industrial water differed significantly from the PS communities in seawater. Both communities have a high potential ability to carry out the carbohydrates and amino acids metabolism, but the potential for xenobiotic degradation, including styrene degradation, was relatively higher in the biofilms in industrial water. Bacteria of the genera Erythrobacter, Maribacter, and Mycobacterium were potential styrene-degraders in seawater, and Pseudomonas and Arenimonas in industrial water. Our results suggest that marine and industrial waters contain microbial populations potentially capable of degrading PS, and these populations may be used for the isolation of efficient PS degraders.

Avis TSC : L’étude de la plastiphère, constituée par tous les microorganismes qui se fixent sur les débris plastiques, apporte sa contribution à la recherche de bactéries pouvant les dégrader. Les familles de bactéries sont différentes lorsque les débris sont immergés dans des eaux industrielles ou dans l’eau de mer, mais elles possèdent en commun la propriété de dégrader le polymère. En milieu naturel, cette dégradation est plutôt lente car le plastique n’apporte qu’une source de carbone organique et ce dernier est déjà très présent dans la matière organique dissoute dans les eaux qui est beaucoup plus facile à dégrader. Pour augmenter cette cinétique, des cultures spécifiques devront être réalisées avec un milieu où seul le plastique apporte le carbone organique.

Impacts de la Pollution Plastique

Confidence intervals and sample size for estimating the prevalence of plastic debris in seabird nests

Tavares, Davi Castro; Moura, Jailson Fulgêncio; Acevedo-Trejos, Esteban; Crawford, Robert J. M.; Makhado, Azwianewi; Lavers, Jennifer L.; Witteveen, Minke; Ryan, Peter G.; Merico, Agostino.

Environmental pollution (Barking, Essex: 1987) : 263 (DocId: Pt A) 114394 (2020).

DOI-Link : https://doi.org/10.1016/j.envpol.2020.114394

Evidence is accumulating about the impacts of plastics on marine life. The prevalence of plastics in seabird nests has been used as an indicator of levels of this pollutant in the ocean. However, the lack of a framework for defining sample sizes and errors associated with estimating the prevalence of plastic in nests prevents researchers from optimizing time and reducing impacts of fieldwork. We present a method to determine the confidence intervals for the prevalence of debris in seabird nests and provide, for the first time, information on the prevalence of these items in nests of the Hartlaub's gull Larus hartlaubii, the African penguin Spheniscus demersus, the great white pelican Pelecanus onocrotalus, and the white-breasted cormorant Phalacrocorax lucidus in South Africa. The method, based on observations and resampling simulations and tested here for nests of 12 seabird species from 15 locations worldwide, allows for straightforward hypothesis testing. Appropriate sample sizes can be defined by combining this method with a Bayesian approach. We show that precise estimates of prevalence of debris in nests can be obtained by sampling around 250 nests. Smaller sample sizes can be useful for obtaining rough estimates. For the Hartlaub's gull, the African penguin, the great white pelican, and the white-breasted cormorant, debris were present in 0.75%, 3.00%, 6.41%, and 25.62% of the respective nests. Our approach will help researchers to determine errors associated with the prevalence of debris recorded in seabird nests and to optimize time and costs spent collecting data. It can also be applied to estimate confidence intervals and define sample sizes for assessing prevalence of plastic ingestion by any organism.

Avis TSC : La présence de débris plastiques dans les nids d’oiseaux est telle que ces auteurs proposent une normalisation de la méthode de comptage, afin que les scientifiques puissent générer des données quantitatives comparables. Ces observations servent d’indicateurs pour l’évaluation et le suivi de la pollution plastique dans une zone. Parmi les oiseaux étudiés dans les mêmes sites, ce sont les cormorans qui utilisent le plus les débris plastiques dans leurs nids (25%) comparativement aux pélicans (6%).

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