Little is known about the prevalence of microplastics (MPs) in East Africa. In the present study, sediments were sampled at 18 sites along the Tanzanian coast that exhibit different levels of anthropogenic activity and were extracted using floatation methodology. Cockles (Anadara antiquata) were collected only from eight sites and MPs were extracted following NaOH digestion. MPs were most abundant at Mtoni Kijichi Creek (MKC, 2972 +/- 238 particles kg(-1)dry sediment), an industrial port in Dar es Salaam, and significantly higher than all other sites where the abundance range was 15-214 particles kg(-1)dry sediment (p < 0.05, one-way ANOVA). Fragments and fibers were found at all sites. Polypropylene and polyethylene were identified polymers. MPs were found in cockles from all sampled sites with both frequencies of occurrence and MPs per individual subject to site-specific variation. This study provides a baseline of MP data in a previously uninvestigated area.

Microplastics in commercially important seafood species is an emerging area of food safety concern. While there have been reports of plastic particles in the gastrointestinal tract of several species, presence of microplastics in edible fish tissues has not yet been reported from India. This study examined the presence of microplastics in the edible (muscle and skin) and inedible (gill and viscera) tissues of nine commercially important pelagic fish species from Kerala, India. A total of 163 particles consisting mainly of fragments (58%) were isolated. Out of 270 fishes analysed (n = 30 per species), 41.1% of the fishes had microplastics in their inedible tissues while only 7% of fishes had microplastics in their edible tissues. The quantity of microplastics in inedible tissue was significantly larger in filter feeders than, that in visual predators (p < 0.05). The average abundance of microplastics in edible tissues was 0.07 +/- 0.26 items/fish (i.e., 0.005 +/- 0.02 items/g) and was 0.53 +/- 0.77 items/fish (i.e., 0.054 +/- 0.098 items/g) in inedible tissues. The results suggest the possibility of human intake of microplastics by the consumption of pelagic fishes from this region, albeit in small quantities.

Microplastics (MPs) are contaminants of emerging concern that have gained considerable attention during the last few decades due to their adverse impact on living organisms and the environment. Recent studies have shown their ubiquitous presence in the environment including the atmosphere, soil, and water. Though several reviews have focused on the occurrence of microplastics in different habitats. little attention has been paid to their interaction with biological and chemical pollutants in the environment. This review therefore presents the state of knowledge on the interaction of MPs with chemicals and microbes in different environments. The distribution of MI's. the association of toxic chemicals with MPs, microbial association with MPs and the microbial-induced fate of MPs in the environment are discussed. The biodegradation and bioaccumulation of MPs by and in microbes and its potential impact on the food chain are also reviewed. The mechanisms driving these interactions and how these. in turn, affect living organisms however are not yet fully understood and require further attention.

Municipal wastewater treatment plants (WWTPs) are known to be important point sources of microplastic pollution in the environment because they discharge large volumes of microplastic-containing effluents into nearby rivers. However, the fate of these microplastics once they enter the urban rivers is not well understood. The present study focused on the Qing River, a typical urban river in Beijing that receives effluents from four nearby WWTPs. We investigated the microplastic pollution profile both at the effluent outfalls from the WWTPs and in the river. Using micro Fourier-transform infrared spectroscopy, we identified and confirmed a total of 18 polymers from the river and effluent outfalls. The microplastics were then separated into four categories based on their shapes with the fragment group being the most abundant, followed by the fiber, film, and pellet groups. Abundance of microplastics was found to be slightly higher in the main body of the Qing River when sampled in November than in July. However, abundance levels from the effluent outfalls were similar in November and in July. Significant amounts of microplastics in the Qing river, up to 80%, were retained upstream of dams that are used for water storage. This result was also confirmed by a decrease in the polymer-diversity index downstream of the dams compared to upstream. A preliminary conclusion could be drawn that the microplastics in the Qing River are mainly released from the WWTPs and that most of these microplastics are retained in the river by dams. (C) 2020 Elsevier B.V. All rights reserved.

Microplastics (MPs) can readily be ingested by marine organisms. Direct ingestion and trophic transfer are likely to be the main pathway for microplastics to bioaccumulate in upper trophic level organisms. Bioaccumulation potential of MPs in marine mammalian foodwebs is scarcely known. To understand whether microplastics bioaccumulate in marine mammals, a bioaccumulation model for MPs was developed for the filter-feeding humpback whale and fish-eating resident killer whale foodwebs of the Northeastern Pacific. Applying three concentration scenarios for MPs by entering observed water and sediment concentrations as input data (low, high, and moderate scenarios), and tested under two different elimination rates (k(E)) for zooplankton, the model predicted species-specific and foodweb-specific bioaccumulation potential. The predator-prey biomagnification factor (BMFTL, used to assess the ratio of the MP concentration in predator to that in prey adjusted to the difference of trophic levels), involving cetaceans, appeared to be not only lower than one or equal to one (BMFTL <= 1 as in resident killer whale/Chinook salmon), but also BMFTL > 1 in some predator-prey relationships (humpback whale/zooplankton). Depending on the magnitude of abiotic concentrations used in the modeling, the trophic magnification factor (TMF) regression analyses over time showed lack of evidence for trophic magnification as the magnification was independent of the trophic level, indicating no changes (TMF = 1; p > 0.05), and trophic dilution (TMF < 1; p < 0.05) due to the decrease in MP concentrations as the trophic level increased. Projected biomagnification in simplified foodwebs revealed no significant increase in concentrations as the trophic level increased (TMF = 1; p > 0.05), following 100-365 days. Compared to the high biomagnification behavior of persistent organic pollutants in marine foodwebs, scarce biomagnification capacity of microplastic was predicted in the cetacean foodwebs. Notwithstanding, the moderate to high microplastic bioaccumulation predicted in some lower trophic level marine organisms highlights the health risks of toxic exposure to marine fauna strongly relying on fish and coastal communities highly dependent on seafood. This modeling work provides a tool to assess the bioaccumulation potential and impact of microplastics in the marine environment to support risk assessment and inform plastic waste management.

The fate of plastic waste is a pressing issue since it forms a visible and long-lived reminder of the environmental impact of consumer habits. In this study, we examine the structural changes in the lamellar arrangements of semicrystalline polyethylene (PE) packaging waste with the aim of understanding the physical mechanisms of embrittlement in PE exposed to the marine environment. PE microplastics and macroplastics from identifiable PE packaging were collected in the Atlantic Ocean and compared to new PE boxes. Several experimental techniques interrogate the effects of environmental exposure on their bulk and surface properties. Size exclusion chromatography determines the molecular weight distribution of the PE polymer chains and differential scanning calorimetry gives the crystallinity. Small- and wide-angle X-ray scattering examines the packing of PE chains into semicrystalline lamellae. Longitudinal acoustic mode Raman spectroscopy provides a complementary measurement of the length of PE polymer chains extending through the crystalline lamellar domains. While there is a high degree of uncertainty in the time scale for the changes, the overall picture at the molecular scale is that although PE becomes more crystalline with environmental exposure, the lamellar order present in new packing boxes is disrupted by the weathering process. This process has important implications for embrittlement and subsequent degradation.

As prime coastal recreational areas, beaches attract an increasing number of users worldwide. However, current studies have shown that beaches are subject to plastic pollution, one of the most significant global environmental threats. Considering the health of tourists and ecological environmental management of beaches, microplastics on recreational beaches are urgently being studied. This paper first focused on microplastics on the recreational beaches of Haichow Bay, which is located on the central coast of China and faces the Yellow Sea. The microplastic pollution level, occurrence, and distribution were investigated. Our study demonstrated that microplastics were consistently found on all studied beaches, which emphasized their extensive distribution throughout recreational beaches. The average microplastic abundance was 106.50 +/- 34.41 items/kg, demonstrating that the microplastic pollution level on the studied beaches tended to be in the middle-to-low position compared with previous studies. In total, eight colors were found, more than 90% of microplastics were less than 1 mm in size, and fiber and fragments were the dominant shapes. Resort beaches contained the highest number of microplastics, indicating that the microplastic pollution level on recreational beaches was directly related to the tourism intensity. Five types of plastic were found in the samples, i.e., polyethylene (PE), polypropylene (PP), PS (polystyrene (PS), polyethylene terephthalate (PET) and nylon. Land inputs were the main source of pollution. This study provided baseline information on microplastic pollution that can be used for effective and comprehensive management of recreational beaches and suggests that the management of plastic use and recycling on beaches should be integrated into China's'coastal zone management practices.

In the field of construction and building materials, many researchers have demonstrated the utilization of fly ash in polymer composites. In a similar way, the present study also focuses on the utilization of machining waste in the field of polymer composites which is proposed for structural applications. Effective utilization of waste wear debris in polymer composites is becoming a potential concern in new materials development. The possibility of using Wirecut-EDM machining waste wear debris in the fabrication of epoxy micro-composites is demonstrated. Three different combinations of WEDM wear debris filled epoxy composites are fabricated, studied their physical, tribological and viscoelastic properties and the results are compared with pure epoxy. WEDM wear debris filled epoxy composites displayed lower wear rate in pin-on-disc test compared to unfilled epoxy. Compared to pure epoxy, the wear rate of composites is significantly reduced when the applied load is high (39.24 N). The storage modulus of 2 wt%, 4 wt% and 6 wt% composites is 22%, 28% and 32% more than the pure epoxy, respectively. The 6 wt% WEDM wear debris reinforced epoxy composite showed better shore D hardness of 93.2 than pure epoxy. In addition, WEDM wear debris reinforced epoxy composites recorded low water absorption compared to pure epoxy. FESEM was used to identify sliding direction and plastic deformation on the composite surface and EDS was used to analyse the presence of various elements in wear debris.

Microplastics are ubiquitous and have been found in marine environments, organisms, salt, and even human bodies. Concern about the impact of microplastics on the ecological environment, as well as the threat of microplastics to food safety and public health is increasing among the society. However, there is currently no effective technical way to tackle and remove microplastics from the environment. Thus, public attitudes are key to reducing microplastic emissions. This study investigated the public's perceptions and attitudes towards microplastics in Shanghai and used an ordered regression model to explore the public's willingness to reduce microplastics and its influencing factors. We used random face-to-face interviews to complete a total of 437 valid questionnaires. The survey results show that only 26% of the respondents had heard of microplastics before the survey, and the majority were relatively unfamiliar with microplastics. Although the public's awareness of microplastics is low compared to that of other substances, when informed with the possibility that microplastics may affect human health, 75% of respondents became worried or even overly worried. In addition, the higher the respondents' knowledge of plastics and microplastics is, the stronger their willingness to behave. Public's concern is also an important impact factor. We found that women's willingness to reduce emissions is higher than men's and environmental protection-related practitioners are also more willing to act. Therefore, this article focuses on the public's understanding of microplastics to propose measures and policy implications to reduce microplastic emissions during the process of microplastic production and recycling.

Expanded polystyrene (EPS) is a common plastic marine debris found in oceans worldwide. The unique "foamed" structure of EPS, which is composed of thin layers, is more vulnerable to fragmentation than bulk plastics. However, the production rate of micro- and nanoplastics by the fragmentation of EPS following sunlight exposure remains largely unknown. Here, we determined the fragmentation rate and weight loss of EPS in an outdoor weathering experiment that ran for 24 months. It took only 1 month for the weight of an EPS box to decline by 5% due to photodegradation, and approximately 6.7 x 10(7) micro- and nanoparticles/cm(2) could be produced at a latitude of 34 degrees N. These results indicate that macro EPS debris can continually produce a massive number of particles within a relatively short exposure duration. The findings provide useful information to inform policymakers how rapidly to remove "likely fragmented" plastic litter from the environment.

Poly(ethylene terephthalate) (PET) from domestic plastic waste was processed by electrospinning from solution hexafluoro-2-propanol/dichloromethane. The nanofibrous membrane with an average diameter of 95 +/- 37 nm was prepared and filtration efficiency was tested. It was shown that the recycled PET (r-PET) nanofibrous membrane retained the particles with a size of around 120 nm with more than 98% efficiency. Moreover, users comfort characteristics such as vapour permeability and breathability were tested. Herein, it is shown that 94% of water vapour permeation is achieved. Breathability 39 mm.s 1 is in the lower limit of the comfortable range; despite this unfavorable result, the r-PET membrane could be used as a filtration media for personal protection because this disadvantage can be mitigated by the area and shape of the filter.

Although wastewater treatment plants can retain a high percentage of microplastics (MP) arriving at the facilities, no method for extracting and characterizing these microparticles has been still standardized in these units. This study investigated three protocols of chemical digestion, prior to analysis of microplastics, one directed to the effluents, using peroxidation, and two for activated sludge (peroxidation and Fenton). The samples (primary effluent, secondary effluent and activated sludge) were collected from a wastewater treatment plant (WWTP) located in Valencia (Spain). In addition, four common types of polymers (Low density polyethylene-LDPE, Polypropylene-PP, Polystyrene-PS and Polyethylene terephthalate-PET) were used to assess the influence of reagent exposure on microparticle integrity. Peroxidation was effective in treating the studied effluents (primary and secondary) and was also identified as the ideal protocol for activated sludge. The analysis showed that the use of H2O2 does not compromise the identification of the polymers evaluated by FTIR and also significantly reduced the concentration of suspended solids, resulting in an efficient visual separation of the microparticles. After been properly separated, the microparticles were characterized according to their size, colour and shape, and a fraction submitted to identification by mu-ATR-FTIR/ATR-FTIR. In all samples, a high presence of microfibers (MF) was observed, corresponding to more than 90% of the microparticles. However, in relation to secondary effluents, only 9% of these MF were identified as plastics, the remaining ones corresponded to cotton. The fragments found in the samples were classified as secondary in origin, and were mainly PE and PP, lower than 1 mm size.

The increasing and simultaneous pollution of plastic debris and antibiotic resistance in aquatic environments makes plastisphere a great health concern. However, the development process of antibiotic resistome in the plastisphere is largely unknown, impeding risk assessment associated with plastics. Here, we profiled the temporal dynamics of antibiotic resistance genes (ARGs), mobile genetic elements (MGEs), and microbial composition in the plastisphere from initial microbial colonization to biofilm formation in urban water. A total of 82 ARGs, 12 MGEs, and 63 bacterial pathogens were detected in the plastisphere and categorized as the pioneering, intermediate, and persistent ones. The high number of five MGEs and six ARGs persistently detected in the whole microbial colonization process was regarded as a major concern because of their potential role in disseminating antibiotic resistance. In addition to genomic analysis, D2O-labeled single-cell Raman spectroscopy was employed to interrogate the ecophysiology of plastisphere in a culture-independent way and demonstrated that the plastisphere was inherently more tolerant to antibiotics than bacterioplankton. Finally, by combining persistent MGEs, intensified colonization of pathogenic bacteria, increased tolerance to antibiotic, and potential trophic transfer into a holistic risk analysis, the plastisphere was indicated to constitute a hot spot to acquire and spread antibiotic resistance and impose a long-term risk to ecosystems and human health. These findings provide important insights into the antibiotic resistome and ecological risk of the plastisphere and highlight the necessity for comprehensive surveillance of plastisphere.

Avis TSC : Les micro-organismes ont deux formes de vie principale l’une en suspension dans l'eau, l'autre fixée à un support. Cette dernière est en général préférée, en particulier dans les environnements ou la quantité de matière nutritive est faible où variable. Sous forme fixée, les micro-organismes vont secréter des exopolymères qui vont permettre l'adhésion au support et aussi la filtration et la captation des matières nutritives et parfois la protection vis-à-vis d'agents toxiques. Ces biofilms sont parfois constitués de plusieurs espèces de microorganismes qui vivent en synergie les uns par rapport aux autres. Ce sont donc de véritables écosystèmes à leur échelle. D'autres modifications significatives interviennent dans ce mode de vie fixé. Le taux d'échange de matériel génétique est fortement augmenté, comparé à celui observé quand les microorganismes restent en suspension dans l'eau. Il en résulte que les gènes contribuant à la résistance aux antibiotiques sont beaucoup plus rapidement transférés d’une bactérie à l’autre dans les biofilms. L'augmentation des microdébris de plastique favorise le développement de ces biofilms et donc la transmission des gènes de résistance aux antibiotiques. Si ces biofilms et ces particules entrent à nouveau dans notre chaîne alimentaire humaine, nous aurons un retour de ces gènes de résistance dans notre organisme, ce qui pourrait poser de sérieux problèmes de santé à court terme. En effet, de nombreuses molécules d'antibiotiques sont maintenant inefficaces et le nombre de nouvelles molécules disponibles se réduit d’année en année.

Politiques & Réglementations

The costs of removing the unsanctioned import of marine plastic litter to small island states

Burt, April J.; Raguain, Jeremy; Sanchez, Cheryl; Brice, Jude; Fleischer-Dogley, Frauke; Goldberg, Rebecca; Talma, Sheena; Syposz, Martyna; Mahony, Josephine; Letori, Jake; Quanz, Christina; Ramkalawan, Sam; Francourt, Craig; Capricieuse, Ivan; Antao, Ash; Belle, Kalsey; Zillhardt, Thomas; Moumou, Jessica; Roseline, Marvin; Bonne, Joel; Marie, Ronny; Constance, Edward; Suleman, Jilani; Turnbull, Lindsay A.

Scientific reports : 10 (DocId: 1)

DOI-Link : https://doi.org/10.1038/s41598-020-71444-6

Small island states receive unprecedented amounts of the world's plastic waste. In March 2019, we removed as much plastic litter as possible from Aldabra Atoll, a remote UNESCO World Heritage Site, and estimated the money and effort required to remove the remaining debris. We removed 25 tonnes at a cost of $224,537, which equates to around $10,000 per day of clean-up operations or $8,900 per tonne of litter. We estimate that 513 tonnes (95% CI 212-814) remains on Aldabra, the largest accumulation reported for any single island. We calculate that removing it will cost approximately $4.68 million and require 18,000 person-hours of labour. By weight, the composition is dominated by litter from the regional fishing industry (83%) and flip-flops from further afield (7%). Given the serious detrimental effects of plastic litter on marine ecosystems, we conclude that clean-up efforts are a vital management action for islands like Aldabra, despite the high financial cost and should be integrated alongside policies directed at 'turning off the tap'. We recommend that international funding be made available for such efforts, especially considering the transboundary nature of both the marine plastic litter problem and the ecosystem services provided by biodiversity-rich islands.

Avis TSC : On voit circuler dans les articles journalistiques et scientifiques des idées pour collecter les plastiques dans l'environnement et éventuellement de les réinjecter dans des boucles d'économie circulaire en développant un modèle économique viable basé sur la valeur de la matière. Les auteurs de ces articles oublient d'étudier la position actuelle des centres de tri à terre qui, malgré une matière abondante et de bonne qualité, ne réussissent pas à obtenir un équilibre économique en vendant ces matières recyclables. Ils sont donc maintenus artificiellement actifs avec des subventions publiques. Compte tenu de cette observation, il est tout à fait improbable de trouver une situation ou la collecte de déchets plastiques dans l'environnement pourrait supporter un modèle économique de recyclage. L'article présenté ici sur des opérations de nettoyage dans des petites îles qui subissent la pollution plastique provenant d'autres pays aligne clairement les chiffres et montre la nécessité d’injecter des moyens pour supporter ces opérations. À titre d'information, l'étude économique du nettoyage de l'atoll d'Aldabra montre que la tonne de déchets revient approximativement à 8900$. Il s'agit de tous les déchets sans considération de ceux qui pourraient entrer à nouveau dans une filière de recyclage. Il est impossible de considérer ces déchets comme une matière première économiquement viable.

Plastics are common in our daily lifestyle, notably in the packaging of goods to reducing volume, enhancing transportation efficiency, keeping food fresh and preventing spoilage, manufacturing healthcare products, preserving drugs and insulating electrical components. Nonetheless, massive amounts of non-biodegradable plastic wastes are generated and end up in the environment, notably as microplastics. The worldwide industrial production of plastics has increased by nearly 80% since 2002. Based on the degree of recyclability, plastics are classified into seven major groups: polyethylene terephthalate, high-density polyethylene, polyvinyl chloride, low-density polyethylene, polypropylene, polystyrene and miscellaneous plastics. Recycling technologies can reduce the accumulation of plastic wastes, yet they also pollute the environment, consume energy, labor and capital cost. Here we review waste-to-energy technologies such as pyrolysis, liquefaction and gasification for transforming plastics into clean fuels and chemicals. We focus on thermochemical conversion technologies for the valorization of waste plastics. This technology reduces the diversion of plastics to landfills and oceans, reduces carbon footprints, and has high conversion efficiency and cost-effectiveness. Depending on the conversion method, plastics can be selectively converted either to bio-oil, bio-crude oil, synthesis gas, hydrogen or aromatic char. We discuss the influence of process parameters such as temperature, heating rate, feedstock concentration, reaction time, reactor type and catalysts. Reaction mechanisms, efficiency, merits and demerits of biological and thermochemical plastic conversion processes are also discussed.

For the past few decades, a plethora of nanoparticles have been produced through various methods and utilized to advance technologies for environmental applications, including water treatment, detection of persistent pollutants, and soil/water remediation, amongst many others. The field of materials science and engineering is increasingly interested in increasing the sustainability of the processes involved in the production of nanoparticles, which motivates the exploration of alternative inputs for nanoparticle production as well as the implementation of green synthesis techniques. Herein, we start by overviewing the general aspects of nanoparticle synthesis from industrial, electric/electronic, and plastic waste. We expand on critical aspects of waste identification as a viable input for the treatment and recovery of metal- and carbon-based nanoparticles. We follow-up by discussing different governing mechanisms involved in the production of nanoparticles, and point to potential inferences throughout the synthesis processes. Next, we provide some examples of waste-derived nanoparticles utilized in a proof-of-concept demonstration of technologies for applications in water quality and safety. We conclude by discussing current challenges from the toxicological and life-cycle perspectives that must be taken into consideration before scale-up manufacturing and implementation of waste-derived nanoparticles.

Politiques & Réglementations

100th Anniversary of Macromolecular Science Viewpoint: Needs for Plastics Packaging Circularity

Billiet, Stijn; Trenor, Scott R.

ACS Macro Letters : 9 (DocId: 9) 1376–1390.

DOI-Link : https://doi.org/10.1021/acsmacrolett.0c00437

Plastic packaging has gained an increasing amount of attention in all aspects of society. Over the past several decades, plastics became the material of choice due to their excellent properties, performance, and economics, but the end of life of plastics is not well managed. This has led to plastic waste in our environment, especially the oceans, rivers, and estuaries, driving legislative, industrial, and voluntary initiatives to make the necessary pivot to circularity. While the plastics recycling industry has made many advances in its relatively short life, there are still many technical and societal hurdles to be overcome. The goal of this work is not to provide a complete review of recycling as it pertains to circularity, but rather to highlight the technical gaps that need to be collaboratively addressed by the entire plastics community to achieve circularity. Each stage along the path, from design of packaging and materials of construction to sortation, recycling, and reprocessing are ripe for innovation. The most relevant issues are introduced to provide a starting point for research across all fields of polymer science to aid in reducing the environmental impact of plastic packaging waste.

Avis TSC : Cet article a été rédigé par deux auteurs qui travaillent dans la société Milliken, qui est l’un des grands fabricants américains de matériau plastique. À la question de l'économie circulaire appliquée à la filière plastique, ils apportent leur expertise très pointue dans le domaine technique. Leurs observations générales sont que de nombreux manques existent à tous les niveaux de la conception au recyclage final des matières, en passant par toutes les étapes du tri, du nettoyage et de la vérification de la qualité des matières tout au long de la chaîne. Cet article est donc une excellente revue de l'état de l'art sur le sujet. Une boucle d'économie circulaire n'est pas uniquement une chaîne linéaire d'utilisation des matières qui reboucle à son point d'origine, mais plutôt une série d'opportunités de réinjecter de la matière ou de l'énergie dans le processus de fabrication. Par exemple, des déchets plastiques de bonne qualité, juste après l'étape de tri, peuvent être réinjectés dans la fabrication des objets en mélange avec du polymère neuf. C'est une première possibilité, si la qualité n'est pas suffisante, une étape de purification peut être ajoutée avant de réutiliser cette matière. Si la qualité est toujours inférieure aux spécifications, une dépolymérisation de la résine peut être envisagée, dans ce cas ce sont les monomères qui sont réinjectés au mélange avec les monomères neufs. Dans le cas où là dépolymérisation n'est pas possible, une conversion chimique est alors envisageable en constituants chimiques élémentaires ou en énergie, qui sont ensuite utilisés dans la chaîne de fabrication. Ce processus peut être décliné suivant les types de résines et les applications. L'étape de purification est souvent critique pour les matériaux triés, car parmi les causes importantes de rejet on trouve les propriétés mécaniques de la résine insuffisantes, la couleur, l'odeur, l'aspect visuel… Cette étape ne peut pas régler tous les problèmes, certains doivent être pris en compte au moment de la conception des matériaux. Dans toute cette approche, l'analyse du cycle de vie constitue un outil très utile pour garder une vue globale sur la mise en place de nouveaux processus et de leurs impacts. La motivation des consommateurs à adopter des comportements de recyclage de qualité est aussi abordée au travers des expériences menées pour donner une valeur aux déchets sous forme de consignes ou d'autres systèmes. Un tri à la source de bonne qualité améliore notablement le rendement de la boucle de recyclage.

Marine plastic pollution is worse than expected, and we are starting to realize its full extent and severity. Solving the plastic pollution problem is not easy, as it requires the action and commitment of all sectors of our society. With a coastline extending over 4,000 km (from 18 degrees S to 56 degrees S), Chile is a maritime country, and since plastics are potentially harmful for marine and coastal ecosystems, food security, and public health, plastic pollution is a real threat. Chile is the sixth-largest exporter of seafood (fish, invertebrates, and algae) in the world, but the extent of plastic contamination of marine organisms, its potential effects on commercial species and aquaculture, and its subsequent effects on human health are mostly unknown. Chile has recently introduced some legislation to prevent plastics from reaching the environment and the coastal ocean. Governmental and non-governmental organizations have joined an informal alliance to take action against plastic pollution, both at a national and regional level, but stronger involvement of producers and commerce is required for effective measures. Chilean scientists working on plastic pollution have created the Scientific Plastic Pollution Alliance of Chile network, aiming to promote collaborative and coordinated research focused on this pollutant. The wide geographical extent of Chile, with researchers working in diverse ecosystems, provides a unique opportunity to better understand the consequences of one of the most recent and severe threats to biodiversity. Rather than solely presenting the plastic pollution problem from the scientific perspective, this paper includes views from different sectors of society. Mitigating plastic pollution is exceptionally complex, with this study highlighting the importance of local engagement, media, solving social inequities, new legislation, and law enforcement in order to advance on decreasing plastic pollution from a country-wide perspective.

Studies documenting plastic ingestion in animals have increased in recent years. Many do not describe the less conspicuous, sub-lethal impacts of plastic ingestion, such as reduced body condition or physiological changes. This means the severity of this global problem may have been underestimated. We conducted a critical review on the sub-lethal impacts of plastic ingestion on marine vertebrates (excluding fish). We found 34 papers which tried to measure plastics' impact using a variety of tools, and less than half of these detected any impact. The most common tools used were visual observations and body condition indices. Tools that explore animal physiology, such as histopathology, are a promising future approach to uncover the sub-lethal impacts of plastic ingestion in vertebrates. We encourage exploring impacts on species beyond the marine environment, using multiple tools or approaches, and continued research to discern the hidden impacts of plastic on global wildlife. (C) 2020 Elsevier B.V. All rights reserved.

Avis TSC : Le nombre de publications sur la pollution plastique ne cesse d'augmenter, à tel point que certains scientifiques demandent un moratoire sur la publication des observations dont la multiplication n'apporte plus d'informations nouvelles. Cet article montre que dans le domaine de l'impact de cette pollution sur la faune, les études sont loin d'être suffisantes. Les taux de mortalité sont assez bien documentés, par contre, les effets sur la morbidité font l'objet d'un nombre réduit de publications. Cet article présente une revue des études sur le sujet et démontre qu’une grande quantité d'impacts sont décrits en cas d’ingestion de plastique chez les vertébrés marins : blocage du système digestif, changements nutritionnels, endommagement des tissus, augmentation de molécules toxiques, modification des conditions de croissance et de reproduction… Ces phénomènes sont plus difficiles à mettre en évidence car ils nécessitent souvent un suivi des populations animales la fréquence régulière. Les auteurs soulignent que la pollution plastique n'est pas la seule source de perturbation, elle intervient en combinaison avec d'autres pressions sur la vie animale, comme la disparition des habitats naturels, la pollution des eaux, la surpêche… Dans ce cas, les animaux sont souvent beaucoup plus fragiles et donc plus réceptifs aux effets de la pollution plastique. Une observation qui peut sans doute être transposée aux effets potentiels de la pollution plastique sur la santé humaine déjà très malmenée de par les conditions de vie et la pollution omniprésente de l'environnement.

Unplanned industrial and urban development are the main sources of increasing concentration of soot and heavy metals in the environment. These pollutants have instigated the deleterious impacts on the environment. Over the past few decades, many researchers have proposed different methods to bring improvement in the environmental quality. These methods include effective combustion techniques that produce less soot and the methods of using soot in the decontamination of environmental compartments polluted with the heavy metals. The aim of this paper is twofold. Firstly, we present a model of an eco-friendly cooking stove to overcome the problem of domestic soot emissions. The proposed model of stove uses a typical type of vented soot filtration hood which contains the soot particulate filters to effectively control soot emissions. Secondly, we study the remediation efficiency of plastic fuel derived soot for heavy metals lead (Pb), nickel (Ni), and chromium (Cr) from the aqueous solutions, contaminated soil, and wastewater samples. A series of batch adsorption experiments are conducted to analyze the effect of different parameters on the heavy metals uptake from aqueous solutions and wastewater samples. The effect of soot application on the heavy metals immobilization from the contaminated soil samples is also studied by using the EDTA extraction method. Experimental results reveal that pH 9.0 is optimal for the adsorption of heavy metals from the aqueous solutions. Soot application to the soil samples increased the pH and reduced 0.1 M EDTA extractable concentration of heavy metals. From the water samples, adsorption of heavy metals increased by increasing the contact time and maximum adsorption occurred at the optimum contact time of 3 hours. Moreover, the experimental data are well modeled through the Langmuir and Freundlich isotherm models. The overall effectiveness of soot in reducing the concentration of heavy metals from aqueous solutions, soil samples, and water samples is as follows: Pb (94.4%, 75%, and 90.5%), Ni (69.97%, 37.4%, and 69.8%), and Cr (61.3%, 37.5%, and 82.6%). It has been inferred from results of this study that soot has a great potential as a remediation tool for the environment excessively contaminated with heavy metals.

The abundance of microplastics in natural systems is a concern even in relatively pristine areas such as Lake Superior, on the border between the United States and Canada. In this study, beach sand and surface water were sampled in the Apostle Islands National Lakeshore (APIS) in May and July 2018. Additional sand samples were collected at non-APIS beaches in western Lake Superior in May 2018. Microlitter particles (<4 mm), consisting of microplastics and other low-density particles, were enumerated. Microplastics in sand samples, as identified by melt test, exhibited low abundances (0 to 55 particles/kg dry weight) and were mainly fibers. Microplastics in water samples were also low in abundance (9000 to 40,000 particles/km(2)) and were mostly fibers. Pyrolysis gas chromatography (pyGCMS) analysis was performed on a subset of microplastics from the sand and water samples. All particles with identifiable mass spectra were polyethylene. When beach sands were processed by density fractionation and filtration, the resulting microlitter samples also contained 260 to 2630 non-plastic particles per kg dry weight. A subset of these nonmelting particles was analyzed by Scanning Electron Microscopy/Energy Dispersive X-ray Spectroscopy (SEM/EDS). Results indicated that both organic and inorganic particles were included within non-plastic microlitter. Re-analysis of additional aliquots of the same sand samples using oxidation in addition to density fractionation reduced the number of non-plastic particles by roughly half, further highlighting that many of these were organic. Post-oxidation surface-water microlitter (333 mu m to 4 mm) also contained non-plastic low-density particles, which comprised 29 to 47% of the total microlitter particle counts. Based upon color distributions, non-plastic microlitter particles in sand and water samples include a small portion or particles identifiable as anthropogenic. The sources for many microlitter particles cannot be distinguished at present and may be natural in origin. (C) 2020 Elsevier B.V. All rights reserved.

Interest in food safety and plastic waste reduction has led to an increase in the search for biopolymer-based coatings within the food industry. The feasibility of preparing an edible coating based on cashew gum polysaccharide (CGP) and polyvinyl alcohol (PVA) was studied. A CGP/PVA coating was characterized for structural, mechanical, barrier and optical properties. Additionally, CGP/PVA edible coatings were bioactivated by immobilization in the film of cell wall degrading enzymes (TCWDE) and applied to the surface of fresh strawberries for evaluation of its fungal growth inhibition capabilities. Scanning electron microscopy results showed that the structure of the CGP/PVA coating was homogeneous without rough surfaces or pores. The CGP/PVA edible coating showed 88% light transmission, a tensile strength of 0.04 MPa, 147% elongation at break and water vapor permeability of 7 x 10(-11) g m(-1)s(-1)Pa(-1). Additionally, it was shown that CGP/PVA and CGP/PVA/TCWDE coatings reduced strawberry-related weight loss and inhibited fungal proliferation. These results suggested that the CGP/PVA hydrogel is a promising material for production of edible antimicrobial coatings.

Avis TSC : Voici à nouveau une étude qui présente le développement d'un matériau polymérique fabriqué à partir de constituants naturels afin de réaliser un emballage comestible. Celui-ci est fabriqué à partir d'un polysaccharide et d'un plastifiant, le PVA (alcool polyvinylique). Les spécifications techniques de protection contre les attaques bactériennes et les moisissures sont atteintes, ainsi que les caractéristiques mécaniques nécessaires. Le seul point qui n'est pas abordé dans cet article, comme dans beaucoup d'articles sur le même sujet, est la protection sanitaire de cet emballage pouvant être ingéré par le consommateur. Faut-il un autre emballage comestible par-dessus ou un emballage surnuméraire en carton ou en plastique pour le protéger ? Pour rester positif, ce genre d'approche pourrait éventuellement être appliquée au sous emballage des portions dans des paquets plus grand, comme pour les gâteaux, qui, pour des raisons de fraîcheur, sont souvent emballés par deux ou par trois sous film plastique dans un container plus grand en carton.

Politiques & Réglementations

Analysis of barriers that impede the elimination of single-use plastic in developing economy context

Vimal, K. E. K.; Mathiyazhagan, K.; Agarwal, Vernika; Luthra, Sunil; Sivakumar, K.

Journal of Cleaner Production : 272

DOI-Link : https://doi.org/10.1016/j.jclepro.2020.122629

Overcoming the issue of elimination of single-use plastic has become one of the biggest ecological scourges in the recent times. The policymakers across the globe have initiated several regulatory policies regarding the elimination of single-use plastics. In the Indian scenario, although the government became somewhat practical in including provisions in the framework of its legislations but still the implementation is at nascent stage. Several studies have cited reasons which hinder the elimination of single-use plastics; however, a comparative study to identify the relationship between these factors has not been carried out in literature which is the motivation behind the present work. With the motivation to cover the aforementioned gaps in the recent literature, the present study aims in identifying the barriers responsible for the difficulty in eliminating single-use plastics and to establish a framework to model and examine the interplay between the barriers. To achieve this, the Decision Making Trial and Evaluation Laboratory (DEMATEL) research framework has been developed. The results demonstrate that 'Lack of manufacturing facilities to meet the demand of biodegradable single-use products', 'Lack of financial support for developing alternatives of single-use of plastics', 'Lack of government initiatives to promote biodegradable single-use products' and 'High cost for technologies for alternative of single-use of plastics' are the most significant barriers in Indian scenario. Thus, it is clear from the study that the advertising of products with the use of single-use plastics does not help in eliminating or changing consumer behavior. Moreover, the dependence of customers over the plastic bag remains the same because it is light, flexible, and most importantly leak-proof and water-resistant. Thus, the government needs to take strong steps in giving financial support and recommendation to form the strategic regulation committee to monitor the issue. Alternative sources of bags also need to be made available to reduce the reliance on single-use plastic bags. The finding of the study is expected to create a single-use plastic-free environment. Based on the understanding through the conduct of the study, the essential policy measures and recommendations were proposed to assist policymakers of government bodies.

Avis TSC : L'interdiction des plastiques à usage unique est une mesure phare de beaucoup de pays concernant leur affichage actif dans la lutte contre la pollution plastique. De plus en plus d'études montrent que cette approche résout relativement peu le problème d’un point de vue quantitatif. Les auteurs présentent ici le cas de l'Inde, qui, comme beaucoup de pays asiatiques, est submergée de sacs plastiques dans son environnement. Le gouvernement a rapidement intégré l'interdiction des sacs et de tous les plastiques à usage unique, mais sans mesure d'accompagnement significative. En particulier, aucune matière de substitution à tarif abordable économiquement n'a été proposée, comme par exemple, des sacs biodégradables. Mais aussi, la publicité poussant à la consommation des produits fait largement appel à des images de plastiques à usage unique, ce qui ne me motive pas les consommateurs à changer leurs habitudes. On voit ici que la réduction de la pollution plastique et nécessairement une approche globale qui remet en cause le modèle économique, le comportement des industriels et des consommateurs. De simples lois interdisant tel ou tel produit n’ont finalement qu’une efficacité très réduite, si ce n'est d’un point de vue communication. Cela permet au pays d'être affiché en vert sur les cartes des nations unies comme étant un pays qui prend en compte la réduction de la pollution plastique par des mesures concrétes.

The impacts of microplastics (MPs) and phthalates (PAEs), a class of MP-associated contaminants, on the marine environment are not thoroughly understood despite concern over their adverse effects on humans and ecosystems. Field studies linking MPs and PAEs in seawater have not yet been reported. We investigate for the first time the correlation between MPs contamination and the presence of PAEs in the surface seawater of Jiaozhou Bay (JZB), a semi-enclosed metropolitan bay in northern China heavily impacted by human activity. The abundance of MPs, dominated by polyethylene and polyethylene terephthalate mostly smaller than 2 mm, ranged between 24.44 items/m(3) and 180.23 items/m(3), with the majority being black and transparent fibers and fragments. Concentrations of PAEs varied from 129.96 ng/L to 921.22 ng/L. Relatively higher abundances of MPs and higher concentrations of PAEs were generally found in areas near riverine inputs and sewage treatment plants. There was a strong correlation between PAEs concentration and MPs abundance, suggesting that they are closely linked. In a risk assessment combining PAEs and MPs, the risk quotients (RQs) indicated that the ecological risk of di-n-butyl phthalate in JZB was relatively high (0.046

Marine plastic pollution is a well-recognized, global problem. Research addressing plastic pollution has largely focused on investigating impacts on macroorganisms, with few studies investigating effects on marine microbes. We previously showed that marine Prochlorococcus, which are important contributors to oceanic primary production, suffer declines in growth and photosynthetic activity following exposure to leachates from new plastic bags (HDPE) and plastic matting (PVC). However, as such plastics reside in the environment they will be subject to weathering processes, so it is also important to consider how these may alter the composition and amounts of substances available to leach. Here we report on how plastic leachate toxicity is affected by environmental weathering (17- and 112-days in estuarine water) of these common plastic materials. We found that while toxicity was reduced by weathering, materials weathered for up to 112-days continued to leach substances that negatively affected Prochlorococcus growth, photophysiology and membrane integrity. Weathered plastics were found to continue to leach zinc, even after up to 112-days in the environment. The two Prochlorococcus strains tested, NATL2A and MIT9312, showed differences in the sensitivity and timing of their responses, indicating that exposure to leachate from weathered plastics may affect even closely related strains to different degrees. As many marine regions inhabited by Prochlorococcus are likely to be subject to continued accumulation of plastic pollution, our findings highlight the potential for ongoing impacts on these important primary producers.

Avis TSC : L'un des effets négatifs potentiels de la pollution plastique et le relargage de substances toxiques contenues dans leur formulation. En effet, les additifs ajoutés au polymère pour fabriquer les plastiques sont parfois des substances polluantes voir toxiques pour l'environnement, comme les métaux lourds, le bisphénol, les phtalates… cette étude a utilisé une bactérie photosynthétique qui est couramment observée dans les milieux aquatiques, afin d'évaluer la toxicité des plastiques rejetés dans l'environnement. En particulier, les auteurs se sont posés la question de savoir si les plastiques qui séjournent dans l'environnement depuis longtemps peuvent être encore toxiques. Sous l'influence du rayonnement UV, de l'eau, du stress mécanique, les débris plastiques se morcellent, se fissurent et rejettent une partie de leurs composés toxiques dans l'environnement. En utilisant la bactérie photosynthétique comme modèle, ils ont mis en évidence que même des débris plastiques ayant séjourné pendant 112 jours dans un environnement aquatique présentent une toxicité significative associée aux composés chimiques (métaux dans ce cas) dans leur formulation. Ils questionnent aussi l'impact plus global de cet effet au niveau des écosystèmes, car cette bactérie constitue l'un des maillons de la production primaire.

Nouveaux Matériaux

Cellulose nanocrystals from grape pomace and their use for the development of starch-based nanocomposite films

Souza Coelho, Caroline Correa de; Soares Silva, Raysa Brandao; Piler Carvalho, Carlos Wanderlei; Rossi, Andre Linhares; Teixeira, Jose Antonio; Freitas-Silva, Otniel; Correa Cabral, Lourdes Maria.

International journal of biological macromolecules : 159, 1048–1061.

DOI-Link : https://doi.org/10.1016/j.ijbiomac.2020.05.046

Nanocomposite films prepared from starch (ST) in the presence of cellulose nanocrystals (CNCs) was performed using grape pomace as raw material. CNCs were obtained by acid hydrolysis and added to filmogenic solutions (1, 2, 5, 10 and 15 g/1 00 g of ST). Cellulose, CNCs and Nanocomposites were characterized. Amorphous non-cellulosic materials were removed from the grape pomace presented values for CrI 64% and 71% and yield 12 and 70% in Cellulose and CNCs, respectively. Nanocomposites showed smaller permeability and the addition of 5 to 15% CNCs formed more opaque films and had improved tensile strength and Young's modulus. The addition of CNCs from 5 to 15% proved to be effective in improving mechanical properties and decreasing water vapor per-meability, important characteristics in food packaging materials. This study provided an effective method to ob-tain CNCs from the agroindustrial waste and open the way to produce high-value starch based nanocomposites.

Avis TSC : L'un des principes de l'économie circulaire et de réduire le nombre de déchets ultimes voire de les supprimer complétement. Cet article présente une approche concernant les matériaux d'emballage. Les auteurs ont utilisé des déchets agricoles constitués de cellulose et d'amidon. Ces déchets sont issus de productions qui sont indispensables à l'alimentation humaine et animale, ils résultent du développement des végétaux dans lesquels seule une partie est utilisée, le reste constituant un déchet. Traditionnellement, les déchets organiques en agriculture sont utilisés pour fertiliser les terres après compostage par exemple. Toutefois les rendements de la production agricole son tels, en particulier dans l'élevage, que les quantités de matière organique disponibles à partir de lisier et fumier sont très importantes et dans certains cas bien supérieures à ce que peuvent absorber les terres agricoles. La réalisation de matière plastique à base d'amidon est connue depuis longtemps, ces matériaux présentent souvent des problèmes de porosité à l'humidité et a l'air. Les auteurs présentent ici une solution en sélectionnant les celluloses des nano cristallines et en les ajoutant à une formulation à base d'amidon. Les résultats techniques montrent que le matériau est tout à fait utilisable comme emballage alimentaire. Compte tenu des volumes de déchets pouvant être ainsi utilisés comme matière première, cette voie paraît intéressante à explorer. Se pose la question du recyclage de cette matière. En effet, elle est très probablement biodégradable et présente donc peu de risques pour l'environnement en cas de perte. Mais la possibilité de la recycler apporterait un plus au niveau économie circulaire.

The characteristics and distribution of plastic litter were evaluated in October 2018 at 40 beaches along the coast of Cadiz Province, in Spain. A total of 14,261 plastic items, appertaining to 57 litter groups, were identified along the study area at different beach zones, i.e. at low tide water level (2%), along the foreshore (6%), at high tide water level (67%) and in the backshore area (25%). Plastic items have a great floatability, being this one of the main reasons for their proportional dominance among beach litter, especially in the wrack line. Hundreds of measurements were made of different items using Raman spectroscopy, an effective technique to determine the type of plastic. Cellulose acetate represented the most abundant material (79%) linked to cigarette butts, followed by polypropylene, 9% and polyethylene, 8%. The remaining were composed by polystyrene, polyethylene terephthalate and polyvinyl chloride. Smoke related items were the most common in the study area, followed by film and hard pieces, cotton bud sticks, fishing strings, food wrappers, caps,lids and single-use plastics. Beach litter can be related to beachgoers but some categories can be attributed to fishing activities or wastewater discharges. Plastics cause a multitude of damages to the coastal ecosystem, due to their toxic components and adsorbed substances and their facility of fragmentation and dispersion. Principal objective is the compositional characterization of plastic beach litter items and their spatial variability. It is therefore important to avoid unnecessary consumption, promote recycling and use other materials that are less harmful to the environment.

The effects of microplastics (MPs) on organisms have drawn a worldwide attention in the recent years. In this study, zebrafish embryos were employed to assess the combined effects of MPs and cadmium (Cd) on the aquatic organisms. Lethal and sublethal effects were recorded at 8, 24, 32, 48 and 96 hpe (hour post exposure, hpe). The exposure under a series concentration of MPs and/or an environmental level Cd has the negative impact on survival and heart rate (HR). And there was a positive correlation between MPs concentration and lethal and sublethal toxicity under combined exposure. The physiological parameters showed that the mixture of two stressors had the antagonistic toxicity under low concentration of MPs (0.05,0.1 mg/L) while the synergistic sublethal toxicity under high levels of MPs (1, 5, 10 mg/L) on zebrafish embryos. Both the scanning electron micrographs (SEM) and fluorescence microscope photos suggested an electrostatic interaction and weak physical forces generated between MPs and chorion membrane. It is inferred that the 10 pro MPs could induce the protective effect of chorion membrane and cause complex toxidties with Cd. But when it involved with other pollutants, the toxic effects and mechanism are still waiting to be figured out. (C) 2020 Elsevier B.V. All rights reserved.

For the conveyor belt, variable material flow influences the energy efficiency of the speed control technology significantly. The fluctuation of material flow on the conveyor belt will lead to the detrimental vibrations on both the belt and the conveyor while the conveyor works at certain speeds. In order to improve the model inaccuracy caused by the uniform bulk material flow assumption in the current conveyor belt model, the paper establishes a high-precision dynamic model that can consider speed control of a conveyor belt under non-uniform bulk material transportation. In this dynamic model, a non-uniform bulk material distribution model is firstly proposed based on laser scanning technology. Then, a high-precision longitudinal dynamic model is proposed to investigate the dynamic behavior of a belt conveyor. Considering the micro-units of actual load on a conveyor belt, it can well describe the transient state of the conveyor belt. These models can be used to determine the optimal speed for safety and energy conservation in operation. Experimental results are used to validate the proposed dynamic model for analyzing belt mechanical behavior under non-uniform bulk material distribution on the belt. The results show that the proposed models can be used for optimizing the operating procedures of belt conveyor systems.

Détection & Caractérisation

Environmental impacts of new Coronavirus outbreak in Iran with an emphasis on waste management sector

Zand, Ali Daryabeigi; Heir, Azar Vaezi.

Journal of Material Cycles and Waste Management

DOI-Link : https://doi.org/10.1007/s10163-020-01123-1

The COVID-19 pandemic have brought several environmental problems worldwide, among which management of municipal solid wastes (MSW) is of great importance due to the effects of solid wastes on soil, air and water resources. This research focused on the emerging challenges in MSW management in Tehran, the capital of Iran, during the COVID-19 pandemic. Tehran has been experiencing higher generation of MSW during the pandemic. Extensive use of personal protective equipments increased textile and plastic wastes considerably. On average, more than 4.5 million pieces of facemasks have been daily discarded by Tehranian residents during the COVID-19 pandemic. Generation of hospital wastes in Tehran also increased by 17.6-61.8% during the pandemic. Legal source separation and recycling programs are still suspended, though waste collection procedure in Tehran has not been subjected to significant changes after the outbreak of the Coronavirus. Hospital wastes, which had been partially separated and treated, are now being collected altogether and landfilled. Waste incineration and composting have been ceased completely; therefore landfilling of MSW has increased by 35% and opted as the only disposal option in Tehran during the COVID-19 outbreak. This research represents a baseline to devise proper urban waste management strategies in developing countries during the COVID-19 pandemic.

Avis TSC : Voici un nouvel article présentant les effets de la pandémie du Covid19 sur la pollution plastique. Il s'agit ici d'observations réalisées en Iran et d'une synthèse présentée par les auteurs. Comme dans tous les pays, l'utilisation des masques et des gants de protection a augmenté considérablement le nombre de déchets plastiques, de même que tous les objets à usage unique utilisés en guise de protection. Plus de 4,5 millions de masques ont été rejetés pendant l'épidémie. Le système de gestion des déchets, en particulier de tri des déchets, ont été stoppés pour des raisons sanitaires. Le compostage et l'incinération ont aussi été stoppés. Les déchets de cette période ont donc été en grande partie mis en décharge, les quantités ont augmenté d'environ 35%. À l'image des masques que l'on retrouve jetés un peu partout dans l'environnement, les autorités de tous les pays se sont précipitées pour faire disparaître ces déchets considérés comme potentiellement dangereux. Un rapide calcul nous montre que l'urgence n'était pas là, sans vouloir stigmatiser le pays présenté ici, en prenant les chiffres indiqués dans la publication, nous avons 4,5 millions de masques qui se sont transformées en déchets. Sachant que la taille d'un masque et environ 20 cm sur 10 cm sur 1/2 cm d'épaisseur, son volume est d'environ 0,1 litre. Donc 4,5 millions de masques représentent 450 m3 de déchets. Était-il difficile de mettre en place une centaine de containers de 5 m3 à l'échelle d'un pays pour collecter ces masques et les traiter tranquillement après la période d'urgence épidémique ? Une simple logistique à mettre en place… Ceci aurait permis de mettre au point une procédure adaptée au traitement de ces déchets spécifiques. Dans tous les pays ou une partie de ces protections individuelles a été mise en décharge, une pollution a été ajoutée à une situation déjà très tendue pour les écosystèmes. Pourtant les solutions par incinération sont pratiquées couramment pour les déchets hospitaliers. Le stockage intermédiaire aurait permis de lisser la charge des incinérateurs.

Détection & Caractérisation

Fate of microplastics in wastewater treatment plants and their environmental dispersion with effluent and sludge

Edo, Carlos; González-Pleiter, Miguel; Leganés, Francisco; Fernández-Piñas, Francisca; Rosal, Roberto.

Environmental pollution (Barking, Essex : 1987) : 259, 113837.

DOI-Link : https://doi.org/10.1016/j.envpol.2019.113837

This work studied the occurrence of microplastics in primary and secondary effluents and mixed sludge of a WWTP as well as in processed heat-dried sludge marketed as soil amendment. Sampled microparticles were divided into fragments and fibres, the latter defined as those with cylindrical shape and length to diameter ratio >3. We showed the presence of 12 different anthropogenic polymers or groups of polymers with a predominance of polyethylene, polypropylene, polyester and acrylic fibres together with an important amount of manufactured natural fibres. The smaller sampled fraction, in the 25-104 μm range, was the largest in both primary and secondary effluents. Fibres displayed lower sizes than fragments and represented less than one third of the anthropogenic particles sampled in effluents but up to 84% of heat-dried sludge. The plant showed a high efficiency (>90%) in removing microplastics from wastewater. However, the amount of anthropogenic plastics debris in the 25 μm - 50 mm range still released with the effluent amounted to 12.8 ± 6.3 particles/L, representing 300 million plastic debris per day and an approximate load of microplastics of 350 particles/m3 in the receiving Henares River. WWTP mixed sludge contained 183 ± 84 particles/g while heat-dried sludge bore 165 ± 37 particles/g. The sludge of the WWTP sampled in this work, would disseminate 8 × 1011 plastic particles per year if improperly managed. The agricultural use of sludge as soil amendment in the area of Madrid could spread up to 1013 microplastic particles in agricultural soils per year.

Avis TSC : Les stations de traitement des eaux usées commencent à produire des données sur le flux de micro plastiques et la possibilité de traiter cette pollution. Les auteurs montrent ici que pour une station traitant des eaux urbaines, des quantités significatives de micro plastique sous forme de fibres et d'autres particules sont observées. Les polymères majoritaires qui ont été identifiés sont le polyéthylène le polypropylène le polystyrène et l'acrylique. L'efficacité des processus de purification en place dans ces stations permet une réduction de 90% du nombre de particules en suspension dans l'eau. Elles assurent donc une dépollution au même titre que la réduction des matières en suspension et des matières organiques. Il reste environ 10% des micro plastiques qui sont rejetés dans la rivière. Se pose alors le problème du traitement des boues qui se forment dans les bassins des stations. Habituellement elles sont valorisées en amendement agricole, car elles sont riches en matière organique. Malheureusement de telles pratiques aboutissent à disperser dans l'environnement les micro-débris de plastique qui ont été collectés dans les eaux. En effet, ces derniers se retrouvent sur les sols et finissent par être intégrés mais ne se dégradent pas, éventuellement ils sont entraînés par les eaux de ruissellement jusqu’à la rivière. Le bilan de ces processus est finalement un rejet de 100% des micro plastiques dans l'environnement. Cet exemple illustre clairement que dans le domaine de l'écologie les problèmes ne sont jamais résolus mais transférés d’un compartiment de l'écosystème à l'autre. Ici, malgré l'efficacité de l'épuration des eaux concernant les micro plastiques, ces derniers sont transférés dans le compartiment solide qui doit aussi être géré. Il n'est pas envisageable de le considérer comme un déchet ultime, ce qui pose un problème majeur dans la gestion des débris plastiques apporté par les eaux usées.

Agricultural films composed of low-density polyethylene (LDPE) have been widely used in farmland, and LDPE microplastics (LDPE-MPs) produced from LDPE degradation can pollute soils and can exert negative effects on biota. Both nitrogen (N) and phosphorus (P) can alter the activity of soil microorganisms and may alter the LDPE-MP degradation process in soils. In this study, LDPE-MP surface morphology, particle size, abundance and mass in a mollisol were evaluated after the application of a gradient of N and P fertilizer in a laboratory incubation experiment. The results showed the following: (1) LDPE-MP particles became fragmented into smaller debris with a coarse surface after 40 days of incubation, and the effect was more obvious with increased P or N application; (2) high N and P fertilization significantly reduced the abundance of LDPE-MP particles >100 μm by 38.5-50.0% and increased the abundance of LDPE-MP particles <20 μm by 43.2-59.5% after 40 days of incubation; (3) high N and P fertilization significantly increased the mass of LDPE-MP particles <75 μm by 25.5-60.1% and decreased the mass of LDPE-MP particles >150 μm by 32.4-37.5%; (4) the mass of LDPE-MPs decreased with increasing incubation time after N and P fertilization, which could be simulated by exponential models (p < 0.05), LDPE degradation was rapid in the first 20 days after N or P fertilization, and both N and P caused a "priming effect" of LDPE degradation; and (5) N and P fertilization increased both the biodiversity and abundance of several predominant genera of soil microorganisms that degrade LDPE. Therefore, N and P fertilization can accelerate LDPE-MP degradation, and the relatively large amounts of fine debris from degraded LDPE-MPs can be problematic for the environment and soil biota. LDPE-MP pollution should be strictly controlled in mollisols, and the degradation mechanisms of LDPE-MPs warrant further study.

Avis TSC : Résoudre une pollution en induisant une nouvelle pollution est un phénomène très fréquent quand on n'a pas une vue globale des écosystèmes et de leur fonctionnement. Les auteurs présentent ici une étude en laboratoire où ils ont observé que l'enrichissement des sols en azote et en phosphore induit une activité bactérienne qui stimule la fragmentation des plastiques de type polyéthylène basse densité. Ils en concluent que cette approche pourrait être une solution favorable à l'intégration des micro-particules de plastique dans les sols. A l'heure ou de grands programmes internationaux prônent une réglementation sur la fertilisation des sols agricoles afin de réduire les phénomènes d'eutrophisation: développement anarchique de végétaux ou d’algues parfois toxiques dans certains d'écosystèmes, il apparaît plutôt dangereux de considérer un apport excessif d'azote et de phosphore comme solution à la réduction des débris plastiques. L'usage de plus en plus fréquent de film plastique pour les cultures sur de grandes surfaces, se fait dans une logique d'économie linéaire car une très faible partie de ces derniers sont récupérés et recyclés, le reste étant rejeté de manière plus ou moins contrôlée dans la nature. Il en résulte une accumulation des débris plastiques dans les sols qui à terme modifieront leur qualité. Rajouter un problème d'eutrophisation à cette pratique n'est certainement pas une bonne idée…

Supercritical water gasification (SCWG) is an innovative conversion method of coal, and mixing with plastic waste can improve the energy production and handle the waste. In this study, co-gasification of lignite and various plastics [polyethylene (PE), polypropylene (PP), and polycarbonate (PC)] in supercritical water was investigated experimentally using quartz reactors. The presence of lignite and these plastics improved the gasification efficiency of each other in co-gasification, indicating a synergistic effect of them in SCWG. The magnitude of the synergistic effect between lignite with PP and PE was higher than that with PC probably because of the higher H/C ratio. The optimal mixing ratio of lignite to these plastics were 1:1, where the maximum promotion of the gasification was obtained. In addition, the co-gasification also reduced the phenol content in the liquid product. Increasing the reaction temperature improved the gasification efficiency and H-2 yield, and the improvement was more significant when it is above 650 degrees C. At 800 degrees C, the highest H-2 yield of 24.17 mol/kg from co-gasification of lignite/PP was obtained. The decrease of the total concentration and prolongation of the reaction time favored the co-gasification of lignite/PP, but the increase of the reaction time had little influence when it is over 30 min. The increase of the reaction time also reduced the content of aromatic hydrocarbons in the liquid product but increased the tar/char formation in the solid residues. The observation of the solid residues by scanning electron microscopy found that some spherical particles (1-2 mu m) were formed during co-gasification of PP and lignite.

Marine debris is a global issue and a hot topic in Thailand. This study involved collecting and quantifying various types of debris at Libong Island. The study area is Libong Island, a small Island in Andaman Sea, with high biodiversity and an important source of sea grass providing a significant and vital habitat for endangered dugongs. Debris was collected on sandy beach and mud beach areas between May and August 2019. The results indicated that the ceramic and glass debris was found in the greatest number followed by plastic and other debris, thin plastic and hard plastic. The major contributing factor for the debris abundance in Libong beach was the shoreline and recreational activities which showed that the land-based sources provided major inputs of plastic pollution at the beaches. The calculation of the Clean Coastal Index (CCI) of Libong Island yielded a result of 5.8 at the sandy beach whereas at the mud beach was 0.65. Thus, the sandy beach was classified as moderately clean and the mud beach was classified as very clean.

Microplastic (MP) pollution of the marine environment is now a growing global concern posing a threat to a variety of species through the ingestion and transfer within food webs. This is considered a potential toxicological threat to marine species due to the chemical additives used to make many plastic products, or the persistent organic pollutants that may accumulate on them while residing in the environment. While the presence of MPs in the marine environment is widely documented, there are no other review articles providing a summary of published effect studies of MPs on the immune and reproductive systems of marine species. This manuscript reviews reproductive and immune-system changes in response to MPs in 7 and 9 species, respectively. Some species such as Mytilus ganoprovincialis and oyster Crassostrea gigas were investigated in multiple papers. Most studies have been conducted on invertebrates, and only 3 studies have been performed on vertebrates, with exposure times ranging between 30 min and 60 days. A review of the literature revealed that the most common MPs types studied in relation to adverse impacts on immune system and reproductive success in marine species were polystyrene (PS) and polyethylene (PE). The immune system's responses to MPs exposure varied depending on the species, with altered organismal defense mechanisms and neutrophil function observed in fish and changes in lysosomal membrane stability and apoptotic-like nuclear alterations in phagocytes reported in invertebrate species. Reproductive responses to MPs exposure, varied depending on species, but included significant reduction in gamete and oocyte quality, fecundity, sperm swimming speed, and quality of offspring. The lack of published data means that developing a clear understanding of the impact across taxonomic groups with different feeding and behavioral traits is often difficult. Further work is required to better understand the risk MPs pose to the immune and reproductive systems of marine species in order to fully evaluate the impact these ubiquitous pollutants are having on marine ecosystems and the associated goods and services they provide.

Microplastic contamination in agroecosystems raises great concerns. Here, we investigated the impacts of mulching and irrigation on microplastic accumulation in cropped soils. Sixty soil samples covering mulching and no-mulching farmlands, and forty-five irrigation water samples were collected for analysis. Microplastics were obtained from the soils using continuous air flotation followed by density separation. Stereomicroscopy and micro-Fourier transform infrared spectroscopy (μ-FTIR) were used for identification. Mulching soils contained larger amounts of microplastics than non-mulching soils, with 571 pieces kg-1 and 263 pieces kg-1, respectively, on average. The abundances of films and fibers were significantly (p < 0.05) higher in the mulching soils. Microplastics in the soils and waters were dominated by fragments and fibers, respectively. The particle size of the microplastics in soils mostly ranged from 1 to 3 mm, and primarily from 90 μm to 1 mm in waters. Multiple polymers, e.g. polyethylene, polypropylene, polyester, rayon, acrylic and polyamide, and shapes found in the soil microplastics indicate contributions from irrigation and plastic waste residues other than plastic mulching. Future studies might include the long-term accumulation of microplastics in agroecosystems from multiple sources under intensively managed cropping systems.