In this work, the artificial photodegradation of polyethylene films was studied in laboratory to compare the fragmentation pathways of this polymer at air and in water. Oxidation, surface mechanical ...properties, crystallinity and crack propagation were monitored to investigate their influence on fragmentation. Without any external stress, fragmentation only occurred in water despite a higher level of oxidation for films weathered at air. The cracking of the films did not appear correlated with the oxidation level and the presence of water appeared as a promoter of cracking propagation. The results also showed that the mechanical properties at the surface play a major role in the fragmentation pathway whereas the fabrication process may influence the propagation direction of the cracks. Consequently, the distribution in size of plastic fragments in the aquatic environment may be linked to the nature of the polymer but also to its manufacturing process. In this study, after 25 weeks of weathering in water, 90% of the fragments were >1 mm with very similar shapes showing that micrometric fragments were not yet abundant. These results suggest that long times of weathering in water and many steps of fragmentation appear necessary from macroplastics to reach sizes <1 mm in the aquatic environment. These results constitute a first attempt to understand the pathways leading from macroplastics to microplastics in water. They have to be confirmed for other polymers and the long-term behavior of the fragments needs to be studied to predict their decrease in size among time.
•Fragmentation of polyethylene films into microplastics were studied in water and at air.•The cracking of films did not appear correlated with the oxidation level.•The presence of water appeared as a promoter of cracking propagation.•The mechanical properties and the fabrication process play a major role in the fragmentation and influence the distribution in size of fragments.•Many steps of fragmentation appear necessary from PE macroplastics to reach microplastics in the aquatic environment.
Monitoring the presence of microplastics (MP) in marine organisms is currently of high importance. This paper presents the qualitative and quantitative MP contamination of two bivalves from the ...French Atlantic coasts: the blue mussel (Mytilus edulis) and the Pacific oyster (Crassostrea gigas). Three factors potentially influencing the contamination were investigated by collecting at different sampling sites and different seasons, organisms both wild and cultivated. Inter- and intra-species comparisons were also achieved. MP quantity in organisms was evaluated at 0.61±0.56 and 2.1±1.7MP per individual respectively for mussels and oysters. Eight different polymers were identified. Most of the MPs were fragments; about a half of MPs were grey colored and a half with a size ranging from 50 to 100μm for both studied species. Some inter-specific differences were found but no evidence for sampling site, season or mode of life effect was highlighted.
•Microplastic contamination of two economical important bivalves•0.61±0.56 and 2.10±1.71 microplastic per mussel and oyster respectively•Domination of grey fragments of PP and PE ranging from 50 to 100μm•No significant effect of location, season or mode of life on quantitative results•A higher frequency of detection in cultivated organisms than wild
The unicellular photosynthetic organisms known as microalgae are becoming one of the most important models for aquatic system studies. Among them,
Chlamydomonas reinhardtii
is widely used as a ...bioindicator of pollution or of different changes in the environment. Numerous pollutants are present in aquatic environments, particularly plastics and nanoplastics. Physiological variations after an environmental change highlight variation in the macromolecular composition of microalgae (proteins, nucleic acids, lipids and carbohydrates). Recently, Fourier transform infrared vibrational spectroscopy has been described as a reliable tool, sensitive and allowing rapid measurement of macromolecular composition of microalgae. Coupled with preprocessing and principal component analysis, it is well adapted to monitoring the effect of environmental stress on biochemical composition. In this study, infrared spectroscopy, combined with multivariate analysis, has been tested first on known environmental stresses such as light intensity variation and nitrogen limitation. Then, this technique has been applied to monitor the interaction and potential impacts of polystyrene nanoparticles on microalgae. The results showed slight variations on protein and carbohydrates bands in the presence of nanoplastics, suggesting that their presence led to modifications in the biochemical composition of the microalgae. To confirm the interaction between microalgae and nanoplastics, visualization by confocal microscopy and cytotoxicity measurement has been carried out. Results showed that polystyrene nanoparticles seemed to adsorb on microalgae surface, leading to a loss of plasma membrane integrity. The resulting chemical modifications, even if moderate, could be detected by infrared spectroscopy‚ showing that this tool could be very helpful in the understanding of nanoparticle-microalgae interaction mechanisms.
In this work, we propose a new protocol for producing model microplastics from an industrial polymer and compare it to a conventional method, cryomilling. Polypropylene industrial pellets were chosen ...due to their widespread production and frequent presence in the environment, making them a notable source of microplastics. Both protocols start with aging under Ultra-Violet light of the pellets but differ in the subsequent mechanical stress applied—strong vs. soft—to break down the photodegraded pellets into microplastics. All generated particles were fully characterized in terms of size, shape, oxidation rate, and stability in aqueous media.
Microplastics produced via cryomilling exhibited significant size and oxidation heterogeneity and tended to aggregate in water. Although the new protocol involving soft mechanical stress required a longer preparation time, it simulated more accurately the environmental degradation of raw plastic. This method successfully produced oxidized microplastics with a controlled size distribution centered around 50 µm which remained stable in water without stabilizers.
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•Model microplastics were generated by mimicking environmental degradation of macroplastics into secondary microplastics.•This new protocol allows to prepare secondary MPs from all types of industrial plastics with control of their composition.•Models of secondary microplastics exhibit good homogeneity in size and oxidation rate.•Model of secondary microplastics prepared with this procedure are stable into water without any stabilizer.
Microplastics are ubiquitous in aquatic ecosystems, but little information is currently available on the dangers and risks to living organisms. In order to assess the ecotoxicity of environmental ...microplastics (MPs), samples were collected from the beaches of two islands in the Guadeloupe archipelago, Petit-Bourg (PB) located on the main island of Guadeloupe and Marie-Galante (MG) on the second island of the archipelago. These samples have a similar polymer composition with mainly polyethylene (PE) and polypropylene (PP). However, these two samples are very dissimilar with regard to their contamination profile and their toxicity. MPs from MG contain more lead, cadmium and organochlorine compounds while those from PB have higher levels of copper, zinc and hydrocarbons. The leachates of these two samples of MPs induced sublethal effects on the growth of sea urchins and on the pulsation frequency of jellyfish ephyrae but not on the development of zebrafish embryos. The toxic effects are much more marked for samples from the PB site than those from the MG site. This work demonstrates that MPs can contain high levels of potentially bioavailable toxic substances that may represent a significant ecotoxicological risk, particularly for the early life stages of aquatic animals.
•Microplastics were collected on beaches from 2 islands in the Guadeloupe archipelago.•MPs collected have similar polymer composition but dissimilar chemical composition.•Leachates from both sites are toxic for sea urchin larvae and jellyfish ephyrae.•Toxicity levels differ between sites.•Toxicity differences may be attributed to differences in chemical impregnation.
Marine plastic pollution is a major environmental issue. Given their ubiquitous nature and small dimensions, ingestion of microplastic (MP) and nanoplastic (NP) particles and their subsequent impact ...on marine life are a growing concern worldwide. Transfers along the trophic chain, including possible translocation, for which the hazards are less understood, are also a major preoccupation. Effects of MP ingestion have been studied on animals through laboratory exposure, showing impacts on feeding activity, reserve depletion and inflammatory responses, with consequences for fitness, notably reproduction. However, most experimental studies have used doses of manufactured virgin microspheres that may not be environmentally realistic. As for most ecotoxicological issues, the environmental relevance of laboratory exposure experiments has recently been debated. Here we review constraints and priorities for conducting experimental exposures of marine wildlife to microplastics based on the literature, feedback from peer reviewers and knowledge gained from our experience. Priorities are suggested taking into account the complexity of microplastics in terms of (i) aggregation status, surface properties and interactions with organic and inorganic materials, (ii) diversity of encountered particles types and concentrations, (iii) particle bioavailability and distribution in experimental tanks to achieve reproducibility and repeatability in estimating effects, and (iv) strict experimental procedures to verify the existence of genuine translocation. Relevant integrative approaches encompass a wide spectrum of methods from -omics to ecophysiological approaches, including modelling, are discussed to provide novel insights on the impacts of MP/NP on marine ecosystems from a long-term perspective. Knowledge obtained in this way would inform stakeholders in such a way as to help them mitigate impacts of the micro- and nano-plastic legacy.
The impact of a microplastic (MPs) mixture composed of polyethylene (PE) and polypropylene (PP) plastic particles, prepared from commercially available products, was evaluated in blue mussels Mytilus ...spp. exposed to three environmentally relevant concentrations: 0.008µg Lˉ¹ (low), 10 µg Lˉ¹ (medium) and 100 µg Lˉ¹ (high). Organisms were exposed for 10 days followed by 10 days of depuration in clean seawater under controlled laboratory conditions. The evaluation of MP effects on mussel clearance rate, tissue structure, antioxidant defences, immune and digestive parameters, and DNA integrity were investigated while the identification of plastic particles in mussel tissues (gills, digestive gland, and remaining tissues), and biodeposits (faeces and pseudofaeces) was performed using infrared microscopy (µFT-IR). Results showed the presence of MPs only in the digestive gland of mussels exposed to the highest tested concentration of MPs with a mean of 0,75 particle/mussel (after the 10 days of exposure). In biodeposits, PE and PP particles were detected following exposure to all tested concentrations confirming the ingestion of MPs by the organisms. A differential response of antioxidant enzyme activities between digestive gland and gills was observed. Significant increases in superoxide dismutase (SOD) and catalase (CAT) activities were measured in the digestive gland of mussels exposed to the low (0.008µg Lˉ¹) and medium (10 µg Lˉ¹) concentrations of MPs and in the gills from mussels exposed to the highest concentration (100 µg Lˉ¹) of MPs that could be indicative of a change in the redox balance. Moreover, an increase in acid phosphatase activity was measured in hemolymph of mussels exposed to 0.008 and 10 µg Lˉ¹ concentrations. No significant difference was observed in the clearance rate, and histopathological parameters between control and exposed mussels. This study brings new insights on the potential sublethal impacts of MPs at environmentally relevant concentrations in marine bivalves.
Diatoms are feedstock for the production of sustainable biocommodities, including biofuel. The biochemical characterization of newly isolated or genetically modified strains is seminal to identify ...the strains that display interesting features for both research and industrial applications. Biochemical quantification of organic macromolecules cellular quotas are time-consuming methodologies which often require large amount of biological sample. Vibrational spectroscopy is an essential tool applied in several fields of research. A Fourier transform infrared (FTIR) microscopy-based imaging protocol was developed for the simultaneous cellular quota quantification of lipids, carbohydrates, and proteins of the diatom
Phaeodactylum tricornutum
. The low amount of sample required for the quantification allows the high throughput quantification on small volume cultures. A proof of concept was performed (1) on nitrogen-starved experimental cultures and (2) on three different
P. tricornutum
wild-type strains. The results are supported by the observation
in situ
of lipid droplets by confocal and brightfield microscopy. The results show that major differences exist in the regulation of lipid metabolism between ecotypes of
P. tricornutum
.
The detection and quantification of micro(nano)plastics in the marine environment are essential requirements to understand the full impacts of plastic pollution on the ecosystem and human health. ...Here, static light scattering (SLS) and dynamic (DLS) light scattering techniques are assessed for their capacity to detect colloidal particles with diameters between d = 0.1 and 0.8 µm at very low concentrations in seawater. The detection limit of the apparatus was determined using model monodisperse spherical polystyrene latex particles with diameters of 0.2 µm and 0.5 µm. It is shown that the concentration and size of colloids can be determined down to about 10−6 g/L. Light scattering measurements on seawater obtained from different locations in Western Europe show that colloidal particles were detected with DLS in seawater filtered through 0.8 µm pore size filters. The concentration of these particles was not higher than 1 µg/L, with an average diameter of about 0.6 µm. We stress that these particles are not necessarily plastic. No particles were detected after filtration through 0.45 µm pore size filters.
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