Burrowing invertebrates induce fragmentation of mariculture Styrofoam floats and formation of microplastics

Plastic litter is rapidly bioeroded in mangrove forests

Due to their architectural and hydrodynamic properties, mangrove forests are emerging as global hotspots for plastic sequestration. Mangroves encroached by coastal cities contain up to two orders of magnitude more plastic than their non-urban counterparts. In urban mangroves, plastic substrata are often used as microhabitats, but the consequences of this interaction for the degradation process of plastics in the environment are unknown. Hence, we hypothesized that plastics are differentially colonized and transformed by distinct macrobenthic assemblages in urban vs. wild mangrove forests. To test this hypothesis, plastic sheets (low-density polyethylene, LDPE; polypropylene, PP; polyethylene terephthalate, PET and expanded polystyrene, EPS) were placed in two positions (on-ground and above ground), and the colonizing biota assessed after four months in urban and wild mangrove forests in the southern Colombian Caribbean. We found 19 plant and animal taxa scraping, burrowing into, biting, fracturing, etching, and boring through plastic sheets, demonstrating that bioerosion is a critical degradation pathway that influence the fate of plastic litter in the environment. As hypothesized, there were significant differences in the structure of macrobenthic biota and functional groups of bioeroders between urban and wild forests. Moreover, the bioerosion rate of EPS and PP was faster in urban than in wild mangrove forests. These findings challenge the view that the biological transformation of plastics is a slow process, mainly driven by microorganisms.

Plastic pollution has the potential to alter ecological and evolutionary processes in aquatic ecosystems

We are beginning to understand the ecotoxicological effects of plastic pollution at the suborganismal, individual, population and community levels, but research has only just begun to explore the ecological and evolutionary impacts of plastic as a new habitat. The global introduction of plastic waste into aquatic environments introduces diverse and variable habitat modifications, altering ecosystems and potentially forming new ecological niches. This widespread habitat modification spans several aquatic ecosystems, including the pelagic ocean, deep-sea benthos, lakes and rivers. Recent studies suggest that habitat modification may interact with and alter ecological and evolutionary processes, affecting populations, communities and species, for example, through feeding ecology, mating behaviour and dispersal. However, further research is necessary to understand the potential long-term effects of plastic pollution on ecological and evolutionary processes across global aquatic ecosystems. Here, we review this emerging field of research and its trajectory.

Deep learning-enhanced hyperspectral imaging for rapid screening of Co-metabolic microplastic-degrading bacteria in environmental samples

Microbial biodegradation of microplastic (MP) emerges as an environmentally benign and highly promising strategy for alleviating MP pollution in the ecosystem. Conventional approaches for screening MP-degrading bacteria use pollutants as the sole carbon source. Co-metabolism plays an essential role in microbial screening, as it enables the discovery of additional degrading microorganisms. However, identifying co-metabolic degrading bacteria is challenging and time-intensive, as not all microorganisms on a co-metabolic medium exhibit degradation capability, increasing the need for refined screening methods. In this study, we propose a novel hyperspectral imaging (HSI) approach to rapidly screen polybutylene adipate terephthalate (PBAT) degrading bacteria directly from co-metabolic media. Hyperspectral images of solid media cultures were acquired, capturing both spatial (image) and spectral (chemical) information. Chemical components in the solid medium exhibit distinct changes under the influence of degrading and non-degrading bacteria. By analyzing the spectral information using machine and deep learning algorithms, it was possible to monitor the PBAT concentration changes in the solid medium, indirectly identifying degrading and non-degrading bacteria. This HSI-based model successfully screened out one kind of PBAT-degrading bacteria validated by traditional method, demonstrating potential for rapid screening of MP-degrading bacteria. With artificial intelligence (AI) technology attracting extensive attention across diverse fields, this study pioneers a new approach for the efficient screening of degrading microorganisms by combining AI algorithms with HSI. This innovative methodology is expected to display significant application potential, thus facilitating the research and development in related fields. SYNOPSIS: This study introduces a highly efficient method to screen co-metabolic MP-degrading bacteria. By combining HSI with deep learning, MP-degrading bacteria can be directly identified on co-metabolism solid media, greatly enhancing the efficiency of screening for MP-degrading microorganisms.

Two sides of the same coin: Weathering differences of plastic fragments in coastal environments around the globe

Plastic debris in coastal environments usually undergoes weathering due to various environmental conditions. However, the weathering effects on exposed and shaded sides of the same plastics are underexplored. In this study, 1573 plastic fragments were collected from 15 coastal sites worldwide between December 2021 and December 2022, and weathering experiments were conducted outdoors. The field investigation showed significant two-sided weathering differences of plastic fragments. The weathering morphology included biota, cracks, delamination, discoloration, etc. The weathering degree was assessed with three metrics, i.e., line density (0-58 mm/mm2), surface loss (0-92 %), and texture index (0-2). The 3D magnitudes of these three metrics revealed the two-sided weathering differences of plastic fragments. Specifically, 43 % of the samples had magnitudes > 5, indicating significant differences. Outdoor simulations suggested that sun-exposed sides developed more cracks, pores, and bubbles, while shaded sides remained smoother. After 12 months, the line density increased from 2.85 to 9.23 mm/mm² for polyethylene (PE) and 4.16-8.47 mm/mm² for polypropylene (PP) (p < 0.05). The carbonyl index increased from 0.50 to 1.70 (PE), from 0.18 to 1.10 (PP), and from 0.45 to 1.57 (polyvinyl chloride). This increase indicated oxidative degradation on sun-exposed sides. Our results highlighted the uneven degree of weathering on both sides of the same plastic fragment due to different environmental factors. The study provided critical insights for creating more accurate models to predict plastic degradation, which will help inform global strategies to reduce plastic pollution.

Bioturbation effects and behavioral changes in buried bivalves after exposure to microplastics

Microplastic pollution has become an increasing concern. Vertical transport of microplastics is one of the major research questions concerning the distribution and fate of microplastics in the marine environment, and biologically mediated vertical transport is particularly significant. However, studies on the effects of different types of benthic organisms on the vertical distribution of microplastics in sediments are still scarce. The results of this study revealed that when exposed to environmentally relevant concentrations of fluorescent polystyrene microbeads (200 µm), Manila clams (Ruditapes philippinarum) exhibited prolonged acclimation period, yet subsequent burrowing behavior (burrowing rate and burrowing velocity) was unaffected. The condition index, clearance rate, and oxygen consumption rate of the clams similarly exhibited no stress response after 14 days of exposure. We determined that microplastics were rapidly transported to deeper layers (6-8 cm below the surface) in the sediment under bioturbation. This study elucidates the mechanisms of microplastic transport, showing that clam behaviors such as burrowing, movement, and ingestion contribute to this process. The results suggest that a biologically based management strategy may be a more environmentally friendly means of mitigating microplastic pollution in seawater.

Environmental impact of microplastic emissions from wastewater treatment plant through life cycle assessment

This study aimed to quantify the environmental impact of microplastic (MP) emissions from wastewater treatment plants (WWTPs) using life cycle assessment (LCA). The investigation comprehensively evaluated the contribution of MPs to overall WWTP midpoint and endpoint impacts, with a detailed analysis of the influence of particle size, shape, polymer type, and the environmental costs and benefits of individual wastewater treatment processes on MP removal. The LCA model was developed using SimaPro software, with impact assessments conducted via the USEtox framework and the IMPACT World+ methodology. Results showed that at the midpoint level, MPs accounted for 1.24E+05 CTUe (94 % of the total plant impact), representing the potential harm to aquatic species per cubic meter of discharged wastewater-surpassing the impacts of other contaminants (e.g., heavy metals, nutrients) by at least two orders of magnitude. At the endpoint level, the damage of 8.39E-02 PDF·m2·yr (1.7 % of the total) indicated the potential loss of species diversity, comparable to other pollutant contributions. Polyethylene, polystyrene, and polypropylene were identified as the most impactful polymer types. In terms of environmental costs and benefits, secondary, tertiary, and primary treatments demonstrated decreasing environmental benefits, directly correlated with their respective MP removal efficiencies. These findings underscore the critical role of MP emissions in WWTP life cycle inventories and highlight the urgent need for targeted environmental policies and advanced treatment technologies to address MP contamination in both natural and engineered aquatic systems.

Novel concept for the healthy population influencing factors

In the rapid urbanization process in China, due to reasons such as employment, education, and family reunification, the number of mobile population without registered residence in the local area has increased significantly. By 2020, the group had a population of 276 million, accounting for over 20% of the total population, making significant contributions to urban economic development and resource optimization. However, the health status of migrant populations is affected by unique issues such as occupational risks and socio-economic disparities, which play an important role in personal welfare, social stability, and sustainable economic growth. The deterioration of the health of the floating population will lead to a decrease in productivity, an increase in medical expenses, and an increase in pressure on the public health system. In order to analyze and predict the main elements affecting the well-being of transient population, this study uses advanced machine learning algorithms such as principal component analysis, backpropagation (BP) neural networks, community analysis, random forest models, etc. Principal component analysis will identify and extract the most important variables that affect the health status of mobile populations. The BP neural network models the nonlinear interaction between health determinants and health outcomes. Community analysis divides the floating population into different health records and promotes targeted intervention measures. The random forest model improves the accuracy and universality of predictions. The insights generated by these models will help develop health policies and intervention policies to improve the health status of mobile populations, narrow disparities, and promote social and economic stability. Integrating data-driven methods and emphasizing a shift towards correct, effective, and impactful public health management provides a robust framework for understanding and addressing the complex health issues faced by mobile populations.

Biodegradation of polystyrene (PS) and polypropylene (PP) by deep-sea psychrophilic bacteria of Pseudoalteromonas in accompany with simultaneous release of microplastics and nanoplastics

Plastics dumped in the environment are fragmented into microplastics by various factors (UV, weathering, mechanical abrasion, animal chewing, etc.). However, little is known about plastic fragmentation and degradation mediated by deep-sea microflora. To obtain deep-sea bacteria that can degrade plastics, we enriched in situ for 1 year in the Western Pacific using PS as a carbon source. Subsequently, two deep-sea prevalent bacteria of the genus Pseudoalteromonas (Pseudoalteromonas lipolytica and Pseudoalteromonas tetraodonis) were isolated after 6 months enrichment in the laboratory under low temperature (15 °C). Both showed the ability to degrade polystyrene (PS) and polypropylene (PP), and biodegradation accelerated the generation of micro- and nanoplastics. Plastic biodegradation was evidenced by the formation of carboxyl and carboxylic acid groups, heat resistance decrease and plastic weight loss. After 80 days incubation at 15 °C, the microplastic concentration of PS and PP could be up to 1.94 × 107/L and 5.83 × 107/L, respectively, and the proportion of nanoplastics (< 1 μm) could be up to 65.8 % and 73.6 %. The film weight loss were 5.4 % and 4.5 % of the PS films, and 2.3 % and 1.8 % of the PP films by P. lipolytica and P. tetraodonis, respectively; thus after discounting the weight loss of microplastics, the only 3.9 % and 2.8 % of the PS films, and 1.3 % and 0.7 % of the PP films, respectively, were truly degraded by the two bacteria respectively after 80 days of incubation. This study highlights the role of Pseudoalteromonas in fragmentation and degradation of plastics in cold dark pelagic deep sea.

Tracing microplastic pollution in Mahi River estuary, Gulf of Khambhat, Gujarat, and their influence on functional traits of macrobenthos

Most maritime habitats contain microplastic (MPs) contamination. The quality of the benthic ecosystem's habitat is declining as MPs accumulate in marine system. The contamination of MPs must therefore be investigated. We studied MPs pollution in the Mahi River, estuary, and macrobenthos. In the present study, the abundance of MPs fragments gradually decreased from the high tide zone to the low tide zone and muddy sediment has high MPs concentrations due to sediment characteristics and particle size. The majority of sediment and biota MPs were fibrous and black. MPs in both silt and biota have identical chemical compositions (modified cellulose), shapes, and colors. A significant source of pollutants and MPs fluxing into the ocean is well within the river system. Perinereis aibuhitensis ingested the most MPs out of 11 species, whereas Amphipods did not show any presence of MPs. Our findings showed that functional characteristics are essential for macrobenthos MPs intake. MPs in macrobenthos are high due to biological functions such as feeding, ecological groups, feeding mechanisms, body size, and bioturbation. MPs in marine sediment and organisms are tracked down to the Mahi River exceeding 50 km. The present work has investigated the idea that the macrobenthos that live in the sediment are ingesting the MPs that are building up there and this ingestion relies on the macrobenthos' functional characteristics.

Continuous generation and release of microplastics and nanoplastics from polystyrene by plastic-degrading marine bacteria

Plastic waste released into the environments breaks down into microplastics due to weathering, ultraviolet (UV) radiation, mechanical abrasion, and animal grazing. However, little is known about the plastic fragmentation mediated by microbial degradation. Marine plastic-degrading bacteria may have a double-edged effect in removing plastics. In this study, two ubiquitous marine bacteria, Alcanivorax xenomutans and Halomonas titanicae, were confirmed to degrade polystyrene (PS) and lead to microplastic and nanoplastic generation. Biodegradation occurred during bacterial growth with PS as the sole energy source, and the formation of carboxyl and carboxylic acid groups, decreased heat resistance, generation of PS metabolic intermediates in cultures, and plastic weight loss were observed. The generation of microplastics was dynamic alongside PS biodegradation. The size of the released microplastics gradually changed from microsized plastics on the first day (1344 nm and 1480 nm, respectively) to nanoplastics on the 30th day (614 nm and 496 nm, respectively) by the two tested strains. The peak release from PS films reached 6.29 × 106 particles/L and 7.64 × 106 particles/L from degradation by A. xenomutans (Day 10) and H. titanicae (Day 5), respectively. Quantification revealed that 1.3% and 1.9% of PS was retained in the form of micro- and nanoplastics, while 4.5% and 1.9% were mineralized by A. xenomutans and H. titanicae at the end of incubation, respectively. This highlights the negative effects of microbial degradation, which results in the continuous release of numerous microplastics, especially nanoplastics, as a notable secondary pollution into marine ecosystems. Their fates in the vast aquatic system and their impact on marine lives are noted for further study.

Exploring marine biofouling on anthropogenic litter in the Atlantic coastline of Morocco

Today, the world is increasingly concerned about marine litter and its interaction with marine biodiversity. However, knowledge concerning the fouling organisms associated with marine litter is very limited in many of the world's marine environments. In this survey, we investigated biofouling on different types of marine litter washed up on all the coasts of the central Atlantic of Morocco. The findings revealed 21 fouling species belonging to 9 phyla (Arthropoda, Mollusca, Echinodermata, Annelida, Bryozoa, Porifera, Chlorophyta, Ochrophyta, and Ascomycota). More specifically, frequently observed fouling species include Mytilus galloprovincialis, Balanus laevis, Megabalanus coccopoma, and Pollicipes pollicipes species. Large marine litter items recorded the highest colonization of marine organisms in comparison to small ones. The frequency of occurrence (FO) of the species most commonly fouled on all coasts was Perforatus perforatus (FO = 48.60), followed by Mytilus galloprovincialis (FO = 45.80), Balanus trigonus (FO = 32.05), Balanus laevis (FO = 30.25), Megabalanus coccopoma (FO = 25.25), Bryozoa species (FO = 19.40), Spirobranchus triqueter (FO = 18.18), Lepas pectinata (FO = 14.45), and Pollicipes pollicipes (FO = 13.05). The majority of the species registered in this study are sessile. Substrate coverage by fouling taxa was significantly different between plastic substrate and other types of marine litter. Likewise, this study revealed that the proportion of fouling organisms is higher on rough surfaces. Overall, this research could be crucial to understanding the little-known subject of marine litter and its colonization by marine biota. Given that these marine litters can act as vectors and cause ecological, biogeographical, and conservation issues in the marine environment, minimizing the quantity of anthropogenic litter reaching the Moroccan Atlantic could significantly reduce its accumulation on the sea surface and seabed, thereby reducing the risk of invasion by non-indigenous species.

Bacterial pathogens associated with the plastisphere of surgical face masks and their dispersion potential in the coastal marine environment

Huge numbers of face masks (FMs) were discharged into the ocean during the coronavirus pandemic. These polymer-based artificial surfaces can support the growth of specific bacterial assemblages, pathogens being of particular concern. However, the potential risks from FM-associated pathogens in the marine environment remain poorly understood. Here, FMs were deployed in coastal seawater for two months. PacBio circular consensus sequencing of the full-length 16S rRNA was used for pathogen identification, providing enhanced taxonomic resolution. Selective enrichment of putative pathogens (e.g., Ralstonia pickettii) was found on FMs, which provided a new niche for these pathogens rarely detected in the surrounding seawater or the stone controls. The total relative abundance of the putative pathogens in FMs was higher than in seawater but lower than in the stone controls. FM exposure during the two months resulted in 3% weight loss and the release of considerable amounts of microfibers. The ecological assembly process of the putative FM-associated pathogens was less impacted by the dispersal limitation, indicating that FM-derived microplastics can serve as vectors of most pathogens for their regional transport. Our results indicate a possible ecological risk of FMs for marine organisms or humans in the coastal and potentially in the open ocean.

Interactions between microplastics and insects in terrestrial ecosystems-A systematic review and meta-analysis

The presence of microplastics (MPs) in terrestrial ecosystems has been confirmed worldwide. Due to their widespread distribution and diversity in habitats, insects will readily interact with MPs via various pathways. Although the topic of MP-insect interactions is still in the early stages of research, it is becoming increasingly important. We used a META approach with phylogenetic control and subgroup examination to summarize the evidence from both field and laboratory experiments in quantitative form. The field evidence suggests that insects can take and transfer MPs along food chains via ingestion and adherence. Also, they are active in the bio-fragmentation of MPs and the generation of secondary pollutants. The exposure to MPs impaired key biological traits of insects, mainly their behavior and health, such as reducing climbing ability and increasing oxidative stress. In terms of exposure conditions, the small-sized MPs can induce more severe effects on the insects, while the insect response to MPs was not significantly reliant on exposure times or MP concentrations based on the current evidence available. We propose that insects not only play roles in the redistribution of MPs spatially and in food chains via bio-fragmentation but are also threatened by MPs. Our research deepens our understanding of the environmental risks posed by MPs in insect ecosystems.

Unveiling Fragmentation of Plastic Particles during Biodegradation of Polystyrene and Polyethylene Foams in Mealworms: Highly Sensitive Detection and Digestive Modeling Prediction

It remains unknown whether plastic-biodegrading macroinvertebrates generate microplastics (MPs) and nanoplastics (NPs) during the biodegradation of plastics. In this study, we utilized highly sensitive particle analyzers and pyrolyzer-gas chromatography mass spectrometry (Py-GCMS) to investigate the possibility of generating MPs and NPs in frass during the biodegradation of polystyrene (PS) and low-density polyethylene (LDPE) foams by mealworms (Tenebrio molitor larvae). We also developed a digestive biofragmentation model to predict and unveil the fragmentation process of ingested plastics. The mealworms removed 77.3% of ingested PS and 71.1% of ingested PE over a 6-week test period. Biodegradation of both polymers was verified by the increase in the δ13C signature of residual plastics, changes in molecular weights, and the formation of new oxidative functional groups. MPs accumulated in the frass due to biofragmentation, with residual PS and PE exhibiting the maximum percentage by number at 2.75 and 7.27 μm, respectively. Nevertheless, NPs were not detected using a laser light scattering sizer with a detection limit of 10 nm and Py-GCMS analysis. The digestive biofragmentation model predicted that the ingested PS and PE were progressively size-reduced and rapidly biodegraded, indicating the shorter half-life the smaller plastic particles have. This study allayed concerns regarding the accumulation of NPs by plastic-degrading mealworms and provided critical insights into the factors controlling MP and NP generation during macroinvertebrate-mediated plastic biodegradation.

A holistic approach on the impact of microplastic discharge from WWTPs to the neighboring environment in Southeast Spain

The present study investigated the release of microplastics (MPs) from wastewater treatment plants (WWTPs) to the neighboring environment, including marine and coastal sediments, and fish. Here, we comprehensively investigated MP abundance in 34 samples of marine sediment, corresponding to 5,530.5 g of sediment (d.w.) collected at -8.0 m, -12.5 m, and -24.0 m, 69 samples of coastal sediment, accounting for 13,617.4 g (d.w.) from 17 different beaches from Mar Menor, and stomach and intestine of 17 fish samples of Sparus aurata, in the vicinity of Cartagena, a port city in Southeast Spain. The results showed that MPs were detected in all marine sediment samples, with an average abundance of 19.4 ± 2.4 items/kg (d.w.), in coastal sediments, with an average abundance of 52.5 ± 5.3 items/kg (d.w.), and fish samples, with an average of 8.2 ± 1.4 items per individual. The contribution of MPs from WWTPs to marine sediments is expected to be slow, as effluents were mostly dominated by fiber and film shapes, and by polymers less dense than seawater. There were no significant variations in the MP abundance of marine sediments after the atmospheric phenomenon named DANA, although a significant smaller MP size was reported, indicating a high mobility for tiny sizes. The same results were revealed for coastal sediment, although variations after DANA were statistically significant. Coastal sediment samples closer to WWTPs and agricultural fields with plastic mulching displayed higher MP concentrations, and an increase in the removal rate of MPs from WWTP effluents was negatively correlated with a decrease in MPs from fish collected. This study highlights the importance of sewage treatment plants in transporting MPs to the aquatic and terrestrial surrounding environment, which warrants further research on human health risks associated to MP pollution.

Holes on surfaces of the weathered plastic fragments from coastal beaches

The surface morphology of weathered plastics undergoes a variety of changes. In this study, 3950 plastic fragments from 26 beaches around the world, were assessed to identify holes. Holes were identified on 123 fragments on 20 beaches, with the highest frequency (10.3 %) being identified at Qesm AL Gomrok Beach in Egypt. The distribution of holes could be divided into even, single-sided, and random types. The external and internal holes were similar in size (37 ± 15 μm) of even type fragments. The external holes were larger than the internal holes in single-sided (516 ± 259 μm and 383 ± 161 μm) and random (588 ± 262 μm and 454 ± 210 μm) fragment types. The external hole sizes were positively correlated with the internal hole sizes for each type. This study reports a novel deformation phenomenon on the surface of weathered plastics and highlights their potential effects on plastics.