Seafloor microplastic hotspots controlled by deep-sea circulation

Microplastic pollution in the littoral environment: insights from the largest Mediterranean Sabellaria spinulosa (Annelida) reef and shoreface sediments

Littoral environments represent the main entry point for pollutants into the sea. Microplastics (MPs) are a growing concern, especially for the Mediterranean basin characterized by densely populated coasts and a semi-enclosed morphology. This article targets MPs associated with a unique coastal habitat - the largest bioconstruction in the Mediterranean (Torre Mileto, Southern Adriatic Sea) built by the reef-building polychaete Sabellaria spinulosa (anellida). We assessed MPs abundance in samples from both bioconstruction and surrounding sediments using stereomicroscopy with UV light and micro-Raman spectroscopy. MPs distribution was analyzed according to substrate (reef vs. sediment), longshore drift (west vs. east side), and reef morphology (hummock vs. platform). Results showed a significantly higher MPs abundance in samples from the western side of the site, potentially related to a longshore drift influence on pollutant distribution. By contrast, no significant differences in MPs abundances were observed in substrates (reefs vs. surrounding sediments) and in reef morphologies (hummock vs. platform), which suggest no direct control of reef-building activity in accumulating MPs. The passive accumulation of MPs, primarily driven by wave action, is likely the main factor explaining the MPs distribution. Micro-Raman Spectroscopy analysis revealed polyethylene terephthalate as the dominant polymer, and fibers as the most abundant morphology; prevalent MPs colors were colorless and black. Data provided here indicate that polychaete reefs temporarily trap MPs, retaining such pollutant in the littoral environment. The mechanism of MPs passive accumulation observed in this study raises questions about the growing risk for this bio-engineered benthic habitats.

Microplastic contamination and ecological risk assessment in sediments and waters of ship-dismantling yards along the Bay of Bengal

This study investigated the extent of microplastic (MP) contamination in sediment and surface water from one of the largest shipbreaking yards along the Bay of Bengal coast. A total of 48 samples (24 each from sediment and water) were collected and analyzed to assess MP abundance, polymer characteristics, sources, and the associated potential ecological risks. MPs were extracted, identified using microscopy and FTIR spectroscopy, and classified by type, color, and polymer composition. MP concentrations averaged 73.54 ± 8.61 items/kg in sediment and 218.56 ± 19.12 items/m3 in water, with fibers being the dominant morphology (87.8-92.1 % in sediment, 91.5-100 % in water). Stations in close to intensive shipbreaking operations exhibited significantly higher abundances. Polymer characterization revealed PET as the dominant type, comprising 37.5 % in water and 25 % in sediment, followed by PS (25 % in both matrices) and PP (12.5 % in water and 25 % in sediment). Ecological risk assessments revealed moderate to considerable contamination levels. Pollution Load Index (PLI) values ranged from 1.02 to 1.433 in sediment and 1.02-1.68 in water. Polymeric Hazard Index (PHI) values reached maximum at 254.37 (sediment) and 265.68 (water), with corresponding Ecological Risk Index (ERI) values reaching 312.88 and 433.06, respectively. Stations S6 and S3, located near areas of intensive shipbreaking activity, exhibited the highest ecological risks. These findings emphasized the urgent need for regulatory intervention and improved waste management.

Microplastic contamination in deep-sea sediments and polymetallic nodules: Insights from the Clarion-Clipperton Zone, Pacific Ocean

This study investigates MPs in sediments and polymetallic nodules collected from the Clarion Clipperton Zone (CCZ) in the Pacific Ocean, using samples collected during a deep-sea mining exploration. MPs were detected in over half of the sediment samples and a third of the nodule samples, with an abundance ranging from 0 to 480 items/kg dry weight (d.w.) and 0 to 80 items/kg d.w. for sediments and nodules, respectively, with no significant difference between the two matrices. In terms of size, the smallest particle found was 0.165 mm in sediments and the largest 10 mm in nodules, being >40 % of the particles counted <1 mm, with fibers being the predominant morphology for both matrices. Transparent and blue particles presented the highest percentages, whereas nodules displayed a more balanced percentage distribution among the observed colors. Raman spectroscopy analysis identified polyacrylonitrile (PAN) and polyethylene terephthalate (PET) as the most abundant polymers, along with pigments like indigo blue (IB), acetoacetic arylide (PY), and phthalocyanine blue (PB) commonly associated with synthetic textiles and industrial sources. A global review of deep-sea MPs (>1000 m) reveals considerable variability in reported concentrations, underscoring the challenge of assessing MP pollution in remote marine environments. The findings highlight the need for standardized methodologies to improve comparability across studies and enhance understanding of MP distribution in deep-sea ecosystems. Given the CCZ's ecological and economic significance, further research is crucial to assess the potential risks posed by MPs in this region.

Unveiling the deep-sea microplastic Odyssey: Characteristics, distribution, and ecological implications in Pacific Ocean sediments

Microplastics (MPs) in deep-sea environments are a growing concern due to their potential ecological risks and the deep sea's role in global biogeochemical cycles. This study investigated the characteristics and distribution of MPs in sediments from the Pacific Ocean at depths of 4900-7016 m across three regions: Western Pacific (WP), Central Pacific (CP), and Eastern Pacific (EP). MPs were detected at all sampling sites, with the highest abundance in WP (111.3 ± 75.1 items/kg dw) and the lowest in CP (49.4 ± 18.7 items/kg dw). Site S9 was recorded as the peak abundance (270.1 ± 107.4 items/kg dw) in WP. MPs were predominantly fibers (94.8 %) in black, gray, and blue hues, mainly composed of polyester and rayon. Statistical analysis showed significant regional variations, reflecting anthropogenic impacts and complex deposition mechanisms. Risk assessments indicated low to medium hazard levels (PLI <10, PRI ≤ III), but the potential ecological impacts remain concerning. This study highlights the significant variability in MP distribution across regions, emphasizing the importance of region-specific mitigation strategies. It calls for comprehensive, long-term research to better understand MP sources, deposition processes, and ecological impacts in deep-sea ecosystems.

Characteristics and spatial distribution of marine litter on the Moroccan Mediterranean coasts: Insights from Al Hoceima region in the central southern Alboran Sea

Marine litter, particularly plastic waste, is a pervasive issue in the Mediterranean Sea, driven by unique oceanographic features and intense anthropogenic pressures, including population growth and seasonal tourism. However, studies on submerged marine waste in the Moroccan Mediterranean, especially on the seabed, remain limited. This study aims to investigate the spatial distribution and key drivers of marine litter accumulation in the Al Hoceima region by integrating trawl survey data with machine learning modeling approaches. The results indicate that plastic accounted for 58 % of the total litter, followed by metal (38 %), rubber (3 %), timber (2.8 %), and cloth (2 %). The distribution of marine litter is primarily influenced by key environmental factors, including elevated sea surface height, proximity to river mouths, shallow bathymetric zones, and distance from the coastline. Wind patterns and marine currents also play a crucial role in litter transport, promoting the offshore movement of floating debris and facilitating its redistribution toward deeper areas and sensitive habitats. The spatial and depth distribution analyses revealed an average debris density of 727 items/km2, with hotspots surpassing 2500 items/km2 observed in shallow waters and areas near river mouths, which are particularly affected by urban discharge and tourism-related activities during peak seasons. Seasonal trends indicate higher densities in spring and summer. Predictive models identified significant litter transfer to deeper waters, with densities reaching 3000 items/km2 during peak months. These findings highlight the urgent need for targeted management strategies, such as reducing riverine waste inputs, improving coastal waste collection, regulating tourism-related waste, and establishing regular monitoring programs, to mitigate the impacts of marine litter and support sustainable waste management policies.

Accurate sampling of undisturbed top sediment from grab sampler collected using aluminum tube and stainless-steel containers for shallow and deep-sea applications

This study describes a sediment sampling protocol using a Kinoshita-type grab (K-grab) sediment sampler to collect and analyze microplastics (<5 mm) and macroplastics (>5 mm) in marine sediments. During the GB24 geological survey cruise aboard the Bosei-maru, 133 surface sediment samples were collected from depths of 20-800 m. The K-grab, equipped with a head-slide weight mechanism, enhanced sampling efficiency across various sediment types. For microplastics, stainless steel containers and J-shaped aluminum tubes minimized contamination while maintaining sample integrity. Macroplastics were separated using a 5 mm mesh and analyzed on board. Method verification confirmed high-spatial-resolution sampling with minimal contamination. These results demonstrate that the K-grab is a reliable tool for microplastic and macroplastic analysis, providing valuable data on plastic pollution in marine sediments.•This study describes a sediment sampling protocol using a grab sampler to collect and analyze microplastics (<5 mm) and macroplastics (>5 mm) in marine sediments.•During the survey, 133 surface sediment samples were collected from depths of 20-800 m, with microplastics handled using J-shaped aluminum tubes and stainless steel containers to minimize contamination while maintaining sample integrity.•Macroplastics were separated using a 5 mm mesh and analyzed on board. Method verification confirmed high-spatial-resolution sampling with minimal contamination.

Microplastics accumulate in all major organs of the mediterranean loggerhead sea turtle (Caretta caretta)

Microplastics (MPs) are a pervasive marine environmental pollutant, posing a serious threat to marine ecosystems and organisms at all trophic levels. Plastic ingestion is well documented in marine turtles, and loggerhead sea turtles (Caretta caretta) have been identified as an indicator species to monitor MP pollution globally. Our understanding of the translocation and bioaccumulation potential of MPs beyond the gastrointestinal tract is, however, limited. Here we demonstrate that MP translocation occurs in these marine reptiles and present a comprehensive analysis of MP accumulation in body tissues of 10 stranded Mediterranean loggerhead turtles including the kidney, liver, spleen, heart, skeletal muscle, subcutaneous fat, stomach, intestine, and reproductive organs. Foreign microparticles were identified in 98.8 % of all samples (∼70 % being MPs) and were significantly concentrated in the reproductive organs followed by the heart. Raman spectroscopy revealed that polypropylene, cotton fibres, and polyethylene were the most common microparticle types, and optical photothermal infrared (O-PTIR) spectroscopy provided direct visualisation of cotton microfibres embedded in loggerhead heart tissue. Future studies should determine the biological impact of MP bioaccumulation in sea turtle organs, to fully appreciate the impacts of these anthropogenic pollutants on protected and vulnerable populations worldwide.

Highly Thermal Conductive and Electromagnetic Shielding Polymer Nanocomposites from Waste Masks

Over 950 billion (about 3.8 million tons) masks have been consumed in the last four years around the world to protect human beings from COVID-19 and air pollution. However, very few of these used masks are being recycled, with the majority of them being landfilled or incinerated. To address this issue, we propose a repurposing upcycling strategy by converting these polypropylene (PP)-based waste masks to high-performance thermally conductive nanocomposites (PP@G, where G refers to graphene) with exceptional electromagnetic interference shielding property. The PP@G is fabricated by loading tannic acid onto PP fibers via electrostatic self-assembling, followed by mixing with graphene nanoplatelets (GNPs). Because this strategy enables the GNPs to form efficient thermal and electrical conduction pathways along the PP fiber surface, the PP@G shows a high thermal conductivity of 87 W m⁻1 K⁻1 and exhibits an electromagnetic interference shielding effectiveness of 88 dB (1100 dB cm-1), making it potentially applicable for heat dissipation and electromagnetic shielding in advanced electronic devices. Life cycle assessment and techno-economic assessment results show that our repurposing strategy has significant advantages over existing methods in reducing environmental impacts and economic benefits. This strategy offers a facile and promising approach to upcycling/repurposing of fibrous waste plastics.

Water environmental capacity of estuarine microplastics capped by species sensitivity threshold

Estuaries are biologically rich ecosystems and act as aggregation zones for microplastic (MP) during their transport from rivers to the sea, posing heightened ecological risks compared to other aquatic environments. However, limit criteria for MP discharge to guide risk management remain lacking. This study quantified the water environmental capacity (WEC) of estuarine MPs using species health-based microplastic concentration (MPC) thresholds. Classified MPs simulation employed probability density functions and shape factors to convert mass concentrations into particle counts during the flood season in the Yangtze River estuary. The 5 % species hazard concentration (HC5) with two ecologically relevant metrics was selected as the MPC threshold by correcting the species sensitivity distribution (SSD) curves for polydispersity and biological accessibility of environmental MPs. Lastly, the dynamic WEC framework was established by linking MP simulations to MPC thresholds. MP aggregation hotspots were found in the intertidal zone and maximum turbidity zone in southern branch, which is akin to locating the 'shortest plank' in bucket effect. The average rescaled MPC in hotspots reached 4.77 × 105particles/(d·m3), accounting for 14.38 % of the WEC safety threshold. This framework explored scientific basis for quantifying the MPs carrying capacity of estuarine ecosystems and allocation of plastic discharge rights.

MPs Entering Human Circulation through Infusions: A Significant Pathway and Health Concern

Human uptake of microplastic particles (MPs) is causing increasing health concerns, and there is mounting pressure to evaluate the associated risks. While MPs can be ingested, breathed in, or drank in, a very direct entrance channel is available through ingress into the bloodstream. Intravenous infusion usually proceeds from plastic bottles. Many are made of polypropylene (PP), and filtering is applied to limit particle contamination. In this study, we examined the MPs' content of filtrates using a combination of surface-enhanced Raman spectroscopy and scanning electron microscopy. We find that the number of PP particles is significant (∼7500 particles/L). The MP sizes range from 1 to 62 μm, with a median of ∼8.5 μm. About 90% of particles ranged between 1 and 20 μm in size, with ∼60% in the range 1 to 10 μm. We then discuss the potential number of such particles injected and the consequences of their presence in the bloodstream. We highlight the organs for potential deposition, and we discuss possible clinical effects. Our quantitative data are important to help evaluate the toxicity risks associated with MPs and to accurately balance those risks versus the benefits of using intravenous injections.

Microplastic contamination in no-take Marine Protected Areas of Brazil: Bivalves as sentinels

Microplastics (MPs) are pervasive environmental contaminants even in remote and pristine locations. Despite extensive literature documenting their widespread presence in marine environments, there is limited understanding of MP contamination in Marine Protected Areas (MPAs), particularly in developing countries. This study assessed MP contamination using multiple filter-feeding bivalve species as sentinels. Samplings were performed during 2022, in ten selected no-take MPAs under different management categories according to the International Union for Conservation of Nature. MPs size, shape, color, and polymeric composition were analyzed using established protocols, including Fourier Transform Infrared (FTIR) spectroscopy. MPs concentrations (0.42 ± 0.34 [0.17-2.00] particles.g-1 ww) peaked at natural monuments, while strict nature reserves and parks were less affected. Based on scientific literature comparison, no-take MPAs were less contaminated by MPs than multiple-use MPAs and unprotected areas in Brazil. However, the observed levels remain concerning, given the potential ecological risks, including trophic transfer, physiological disruptions, and habitat degradation. Around 59% of MPs were organic polymers and alkyd (28%), while polyethylene terephthalate (14%) was the main anthropogenic polymer. MPs were predominantly black, white, or transparent fragments measuring <1000 μm, not differing among MPAs individually or grouped protection category, therefore displaying the consistent qualitative patterns along the Brazilian coast. This study underscores the ecological risks posed by MPs in MPAs, emphasizing the need for long-term monitoring programs and targeted mitigation strategies, contributing to global efforts assessing and managing MP contamination, aligning with the 11th Aichi Target to reduce pressures on biodiversity and promote marine ecosystems sustainable use.

Microplastics in the deep: Suspended particles affect the model species Mytilus galloprovincialis under hyperbaric conditions

Microplastics (MPs) are small plastic particles that result from the degradation of bigger fragments or introduced into the environment as primary particles. Their reduced size makes them available for ingestion by marine organisms, particularly in subtidal and deep-sea environments, which represent the largest sinks for MPs in the ocean. However, there is a lack of data regarding the effects of MPs in subtidal and deep-sea ecosystems. Thus, the present study aimed to assess the effects of MPs under hyperbaric conditions. Juvenile mussels, Mytilus galloprovincialis, were exposed to three concentrations of polyethylene MPs: 0.1, 1 and 10 mg/L, in a mixture of sizes (38-45, 75-90 and 180-212 μm), at different pressures: 1, 4 and 50 Bar, for 96 h. After exposure, the filtration rate, biochemical markers of oxidative stress and transcriptomic profile were analyzed to assess the effects of MPs. Results indicate that MPs affected functional endpoints, with a significant decrease in the filtration rate of mussels exposed to MPs at 1 mg/L and higher. Similarly, all tested oxidative stress biomarkers were affected in a treatment, concentration and pressure-dependent manner. RNA-seq analysis performed in organisms exposed to 1 mg/L of MPs at 4 Bar identified several affected signaling pathways (430 differentially expressed genes) including cellular senescence, the MAPK, RAS PI3K-Akt signaling pathways, apoptosis, among others. Overall, the results here presented corroborate the hypothesis that MPs affect exposed organisms under short-term hyperbaric conditions. These findings highlight the need to study MPs effects in subtidal and deep-sea taxa and address, in future studies, combined effects with other stressors such as contaminants that might be sorbed to the surface of the particles. These findings also indicate that improving hazard assessment of MPs under hyperbaric conditions is paramount to support risk assessment and the implementation of mitigation strategies.

Comparison of Microplastics between Lung Tissues and Intestinal Contents in Finless Porpoises (Neophocaena asiaeorientalis)

Microplastics are ubiquitous environmental pollutants in terrestrial, marine, and atmospheric ecosystems. Plastic inputs into the atmosphere occur through weathering or abrasion, dispersing microplastics globally, which can enter the animals' respiratory systems through inhalation. We analyzed the lung tissues for the first time and the intestinal contents of 11 dead finless porpoises (Neophocaena asiaeorientalis) to assess the intake of microplastics from prey and atmospheric sources. The lung tissues and intestinal contents contained average concentrations of 0.14 ± 0.11 MPs/g and 0.35 ± 0.36 MPs/g, respectively. Microplastics found in the lung tissues and intestinal contents were similar in physical characteristics (e.g., fragment shape, transparent to white color, and size <100 μm). On the other hand, they differed in the polymer types, with a higher proportion of epoxy-type microplastics in the lungs. Epoxy is a highly hazardous polymer according to the polymer hazard index, and in the present study, the lung tissues had a higher plastic hazard index than the intestinal contents. Hence, the respiratory system is more vulnerable to microplastic pollution from atmospheric sources than the digestive system is from water and food intake. These findings underscore the growing threat of airborne microplastics to lung-breathing animals including marine mammals.

Ocean current modulation of the spatial distribution of microplastics in the surface sediments of the Beibu Gulf, China

Microplastic pollution, a major global environmental issue, is gaining heightened attention worldwide. Marginal seas are particularly susceptible to microplastic contamination, yet data on microplastics in marine sediments remain scarce, especially in the Beibu Gulf. This study presents a large-scale investigation of microplastics in the surface sediments of the Beibu Gulf to deciphering their distribution, sources and risk to marginal seas ecosystems. The results reveal widespread microplastic contamination, with an average abundance of 391 ± 27 items/kg in sediments. The spatial variability of microplastic abundance was significant, with lower levels in the western Beibu Gulf and higher concentrations in the northeastern and southeastern regions. The spatial distribution of microplastics was largely driven by geological features, hydrodynamic conditions, and human activity, with minimal influence from local environmental factors such as water depth, sediment grain size, organic carbon content, and sediment types. The pollution load index (PLI) suggests a low level of microplastic contamination, but the polymer hazard index (PHI) identified a high ecological risk, likely due to the presence of PVC, a polymer with higher chemical toxicity. Our findings highlight the significant role of hydrodynamic processes in determining microplastic distribution in the Beibu Gulf. These insights enhance our understanding of microplastic dispersal and its governing factors in semi-enclosed marginal seas, providing foundation for targeted pollution control strategies.

The distribution of subsurface microplastics in the ocean

Marine plastic pollution is a global issue, with microplastics (1 µm-5 mm) dominating the measured plastic count1,2. Although microplastics can be found throughout the oceanic water column3,4, most studies collect microplastics from surface waters (less than about 50-cm depth) using net tows5. Consequently, our understanding of the microplastics distribution across ocean depths is more limited. Here we synthesize depth-profile data from 1,885 stations collected between 2014 and 2024 to provide insights into the distribution and potential transport mechanisms of subsurface (below about 50-cm depth, which is not usually sampled by traditional practices3,6) microplastics throughout the oceanic water column. We find that the abundances of microplastics range from 10-4 to 104 particles per cubic metre. Microplastic size affects their distribution; the abundance of small microplastics (1 µm to 100 µm) decreases gradually with depth, indicating a more even distribution and longer lifespan in the water column compared with larger microplastics (100 µm to 5,000 µm) that tend to concentrate at the stratified layers. Mid-gyre accumulation zones extend into the subsurface ocean but are concentrated in the top 100 m and predominantly consist of larger microplastics. Our analysis suggests that microplastics constitute a measurable fraction of the total particulate organic carbon, increasing from 0.1% at 30 m to 5% at 2,000 m. Although our study establishes a global benchmark, our findings underscore that the lack of standardization creates substantial uncertainties, making it challenging to advance our comprehension of the distribution of microplastics and its impact on the oceanic environment.

Microplastics/nanoplastics contribute to aging and age-related diseases: Mitochondrial dysfunction as a crucial role

The pervasive utilization of plastic products has led to a significant escalation in plastic waste accumulation. Concurrently, the implications of emerging pollutants such as microplastics (MPs) and nanoplastics (NPs) on human health are increasingly being acknowledged. Recent research has demonstrated that MPs/NPs may contribute to the onset of human aging and age-related diseases. Additionally, MPs/NPs have the potential to induce mitochondrial damage, resulting in mitochondrial dysfunction. Mitochondrial dysfunction is widely recognized as a hallmark of aging; thus, it is necessary to elucidate the relationship between them. In this article, we first elucidate the distribution of MPs/NPs in various environmental media, their pathways into the human body, and their subsequent distribution within human tissues and organs. Subsequently, we examine the interplay between MPs/NPs, mitochondrial dysfunction, and the aging process. We aspire that this article will enhance awareness regarding the toxicity of MPs/NPs while also offering a theoretical framework to support the development of improved regulatory policies in the future.

Settling velocities of microplastics with different shapes in sediment-water mixtures

The widespread distribution of microplastics (MP) in aquatic systems highlights the need for a clear understanding of how they are transported and accumulate on the bottom of water bodies. Developing predictive models for MP dispersion, sedimentation, and bioaccumulation is crucial for informing regulatory decisions and mitigating the impact of MP and related pollutants. Among the key parameters, MP settling velocity is considered the most critical for predicting their behavior in aquatic environments. Recent studies suggest an intricate and not fully understood relationship between MP settling and sediment dynamics. To date, none of the current models can predict how sediment modifies MP settling velocity. Therefore, previous understanding on MP settling does not fully account for the sedimentation of MP in aquatic ecosystems, where sediment suspension is present. This study provides further evidence that the presence of sediment alters the sedimentation rate of MP based on their shape, offering a quantitative estimate of this interaction. For the first time, the effects sediment interaction has on MP sinking trajectories and inclinations are presented. A preliminary, modified version of an existing formula is proposed to estimate MP settling velocity in the presence of sediment, laying the groundwork for more accurate predictive models of MP transport in aquatic environments.

Direct Evidence That Microplastics Are Transported to the Deep Sea by Turbidity Currents

Microplastics pervade the global seafloor, yet the mechanisms by which this pollutant is increasingly transported to the deep sea remain unclear. Fast-moving sediment avalanches (called turbidity currents) are hypothesized to efficiently transport microplastics into the deep sea. However, while this has been inferred from field sampling of the seafloor, it has never been demonstrated outside of a laboratory setting. Here, we provide direct field-scale evidence that turbidity currents in submarine canyons not only transport globally significant volumes of mineral and organic matter into the deep sea but also carry large quantities of anthropogenic particles, including microfibers and microplastic fragments. In situ hydrodynamic monitoring, coupled with direct sampling of the seafloor and material suspended by turbidity currents, reveals that even a submarine canyon whose head lies hundreds of kilometers from land acts as an efficient conduit to flush sediment and pollutants from the continental shelf to water depths greater than 3200 m. Frequent and fast turbidity currents supply oxygen and nutrients that sustain deep-sea biodiversity and fishing grounds in, and adjacent to, such canyons. Our study therefore confirms that these biodiversity hotspots are colocated with microplastic hotspots, indicating that the more than 5000 land-detached canyons worldwide can be important but previously unproven conveyors of anthropogenic pollution to the deep sea.

Unraveling the Impact of Microplastic-Tetracycline Composite Pollution on the Moon Jellyfish Aurelia aurita: Insights from Its Microbiome

Microplastics have emerged as a pervasive marine contaminant, with extreme concentrations reported in deep-sea sediments (e.g., 1.9 million particles/m2) and localized accumulations near Antarctic research stations. Particular concern has been raised regarding their synergistic effects with co-occurring antibiotics, which may potentiate toxicity and facilitate antibiotic resistance gene dissemination through microbial colonization of plastic surfaces. To investigate these interactions, a 185-day controlled exposure experiment was conducted using Aurelia aurita polyps. Factorial combinations of microplastics (0, 0.1, 1 mg/L) and tetracycline (0, 0.5, 5 mg/L) were employed to simulate environmentally relevant pollution scenarios. Microbiome alterations were characterized using metagenomic approaches. Analysis revealed that while alpha and beta diversity measures remained unaffected at environmental concentrations, significant shifts occurred in the relative abundance of dominant bacterial taxa, including Pseudomonadota, Actinomycetota, and Mycoplasmatota. Metabolic pathway analysis demonstrated perturbations in key functional categories including cellular processes and environmental signal transduction. Furthermore, microplastic exposure was associated with modifications in polyp life-stage characteristics, suggesting potential implications for benthic-pelagic population dynamics. These findings provide evidence for the impacts of microplastic-antibiotic interactions on cnidarian holobionts, with ramifications for predicting jellyfish population responses in contaminated ecosystems.

Circular Economy and Chemical Conversion for Polyester Wastes

Polyester waste in the environment threatens public health and environmental ecosystems. Chemical recycling of polyester waste offers a dual solution to ensure resource sustainability and ecological restoration. This minireview highlights the traditional recycling methods and novel recycling strategies of polyester plastics. The conventional strategy includes pyrolysis, carbonation, and solvolysis of polyesters for degradation and recycling. Furthermore, the review delves into exploring emerging technologies including hydrogenolysis, electrocatalysis, photothermal, photoreforming, and enzymatic for upcycling polyesters. It emphasizes the selectivity of products during the polyester conversion process and elucidates conversion pathways. More importantly, the separation and purification of the products, the life cycle assessment, and the economic analysis of the overall recycling process are essential for evaluating the environmental and economic viability of chemical recycling of waste polyester plastics. Finally, the review offers perspective into the future challenges and developments of chemical recycling in the polyester economy.

When microplastics meet microalgae: Unveiling the dynamic formation of aggregates and their impact on toxicity and environmental health

Microplastics (MPs) commonly coexist with microalgae in aquatic environments, can heteroaggregate during their interaction, and potentially affect the migration and impacts of MPs in aquatic environments. The hetero-aggregation may also influence the fate of other pollutants through MPs' adsorption or alter their aquatic toxicity. Here, we explored the hetero-aggregation process and its key driving mechanism that occurred between green microalga Chlorella vulgaris (with a cell size of 2-10 μm) and two types of MPs (polystyrene and polylactide, 613 μm). Furthermore, we investigated the environmental impacts of the microplastics-microalgae aggregates (MPs-microalgae aggregates) by comparing their adsorption of Cu(II) with that of pristine MPs and evaluating the effects of hetero-aggregation on MPs aging and their toxicity to microalgae. Our results indicated that microalgal colonization occurred on the surface of MPs, possibly through electrostatic interactions, hole-filling, hydrophilic interactions, and algae-bacteria symbiosis. The hetero-aggregation led to a stronger Cu(II) adsorption by MPs-microalgae aggregates than pristine MPs due to electrostatic interactions, coordination, complexation, and ion exchange. Exposure to either MPs (pristine or aged) or Cu(II) inhibited the cell growth of C. vulgaris, while the integrated biomarker response (IBR) showed more pronounced inhibitory effects resulting from aged MPs compared to pristine MPs and an antagonistic effect on microalgae was caused by the co-exposure to MPs and Cu(II). These findings suggest that the hetero-aggregation of MPs and microalgae may alter their environmental fates and co-pollutant toxicity.

Microstructure and performance evolution of poly (l-lactic acid) during physical aging: Determinable role of molding method on β-relaxation

As one of the biodegradable materials, poly (L-lactic acid) (PLLA) attracts much attention and acquires fast development since it is crucial for alleviating the issue of microplastic pollution. During processing and service, polymers usually experience the physical aging process, leading to the microstructure and performance evolution. Such scenario is especially obvious for PLLA. However, the mechanisms involved remain unclear. Here, the relationship between ductility and relaxation behavior of PLLA during physical aging is investigated. The ductility is greatly dependent upon the molding method, and the quenched samples show higher tensile ductility compared with cold-pressed samples. The cohesional entanglement gradually forms with aging time, and it is closely related to molding methods. The cohesional entanglement has no impact on the α-relaxation process, nevertheless, it greatly restricts the β-relaxation of PLLA. The decrease in the mobility of molecular chains makes it unable to effectively absorb energy when subjected to external forces. Furthermore, physical aging is an irreversible process while quenching treatment can retard the physical aging behavior of PLLA for a certain period. This work provides new insight on the microstructure and performance evolution mechanisms of PLLA during physical aging, which can guide the microstructure design of PLLA-based articles with promising performances.

Plastic debris exposure and effects in rivers: Boundaries for efficient ecological risk assessment

Until recently, plastic pollution research was focused on the marine environments, and attention was given to terrestrial and freshwater environments latter. This discussion paper aims to put forward crucial questions on issues that limit our ability to conduct reliable plastic ecological risk assessments in rivers. Previous studies highlighted the widespread presence of plastics in rivers, but the sources and levels of exposure remained matters of debate. Field measurements have been carried out on the concentration and composition of plastics in rivers, but greater homogeneity in the choice of plastic sizes, particularly for microplastics by following the recent ISO international standard nomenclature, is needed for better comparison between studies. The development of additional relevant sampling strategies that are suited to the specific characteristics of riverine environments is also needed. Similarly, we encourage the systematic real-time monitoring of environmental conditions (e.g., topology of the sampling section of the river, hydrology, volumetric flux and velocity, suspended matters concentration) to better understand the origin of variability in plastic concentrations in rivers. Furthermore, ingestion of microplastics by freshwater organisms has been demonstrated under laboratory conditions, but the long-term effects of continuous microplastic exposure in organisms are less well understood. This discussion paper encourages an integrative view of the issues involved in assessing plastic exposure and its effects on biota, in order to improve our ability to carry out relevant ecological risk assessments in river environments.

Rapid detection and quantification of Nile Red-stained microplastic particles in sediment samples

The distribution and migration processes of microplastics (MPs) in the marine sediments have yet to be fully elucidated. To estimate the contamination levels and distribution patterns, and develop countermeasures, the amount of MPs must be understood. Rapid and efficient processing of numerous samples is also needed to detect and determine MP contamination. However, whatever the sample of interest, MP analysis is time consuming. This is especially the case for deep-sea sediments, where the particle sizes are small and pretreatment processes are complex and time-consuming. To address the need for rapid and efficient detection of MPs, we propose a novel method for automatically identifying and counting Nile Red (NR)-stained sedimentary MP particles captured under a stereoscopic fluorescence microscope. In this study, we demonstrated the utility of the developed system by comparing its recovery rate and analysis time with those of the conventional methods used for manual processing. The developed method can efficiently detect MPs of sizes between 18 and 500 µm and classify them as fibers or grains (or fragments). This means that our method can efficiently detect MPs as small as 100 µm found in deep-sea sediments. The semi-automated MP detection system gave a counting time of 4.2-8.8 s per particle-as the number of particles increases, the analysis time per particle decreases. Similarly, when the number of particles counted using a stereomicroscope and image analysis software was set at 100, the automatic measurement method using a flow cell could measure 50-80% of the total number of particles, depending on the type of MPs. By using artificial particulate and fibrous MPs as training data and combining them with a machine learning system, we were able to build a system that can classify both types with 98% accuracy (100% for fibers and 96% for grains). In natural samples, approximately 150 µm (20-350 µm in range) MPs were detected, and the number was consistent with previous studies. This demonstrates the effectiveness of the method we developed. We established a rapid detection method for the number and form of MPs using a continuous semi-automated method, combining NR staining and artificial intelligence. Although this method does not allow the identification of polymer types, it enables that rapid and reliable quantification of MPs numbers. The new method established in this study is expected to improve the accuracy of information on the distribution, destination, and quantity of MPs. It is also relatively easy to use and can transfer technology in various fields, from citizen science to rapid diagnosis on research vessels in the open ocean.

The impact of building uses on microplastic pollution and its implications for environmental education

Rivers are major sources of marine microplastics. To investigate the influence of building use on river microplastic pollution, this study focused on the Chongqing section of the main stream of the Yangtze River. Surface water and sediment microplastic samples were collected and analyzed alongside building use data to explore the relationship between microplastic abundance and building use at different spatial scales. The results showed that: (1) The abundance of microplastics in surface water and sediment in the Chongqing section of the Yangtze River exhibited an inverse distribution pattern. In the upper reaches, the central urban area of Chongqing showed significantly higher microplastic levels in surface water (6,811 ± 3,101 n/m ³) compared to the lower reaches, confirming the direct input effect of high-intensity human activities. The accumulation of microplastics in sediment was greater in the northeastern section of Chongqing compared to the lower reaches (89.6 ± 69 vs. 45.4 ± 28 n/kg), indicating a hydrodynamic-driven sedimentation lag effect. (2) The influence of building use on microplastic abundance in surface water was significantly scale-dependent. Industrial buildings within a 2 km buffer zone explained up to 61.16% of the observed variance, suggesting cross-medium migration through atmospheric sedimentation and sewage pipe network. (3) Compared to land use types, building uses dominate the abundance distribution of microplastics in surface water at larger buffer radius (1-2 km), indicating that high-intensity human activities have a greater impact on spatial differentiation of microplastic pollution. It is recommended to implement hierarchical control measures along the Chongqing section of the Yangtze River. A 2-km ecological buffer zone is set up in industrial agglomeration areas to strictly supervise wastewater discharge from plastic products enterprises. Rainwater bioretention facilities are built within 1 km of densely populated areas to intercept microplastics from domestic sources, such as laundry fibers. This study explores the mechanism by which building use affects river microplastic pollution, providing valuable insights for microplastics control in large river basins worldwide.

Microplastics in Bays along the Central Texas Coast

Estuarine and bay environments, which can act as sediment traps along the inner parts of continental shelves, may host significant depositional hotspots for plastic debris. This research targets Texas coastal bays (Matagorda and San Antonio), to better understand microplastic contamination in sediments and provide insight into the processes controlling its distribution. Microplastic extraction and quantification methods employed include sediment sieving, elutriation, microscopy, and spectroscopy. This study found low concentrations (ca. 10s-100s particles kilogram-1 sediment or 20-200 × 104 items meter-3 wet sediment) and negligible correlations between analyzed deposit constituents (R2 for grain size = -0.14 to 0.12, organic content = 0.08, water depth = -0.11, distance to shore = -0.14). The highly dynamic role of wind-driven mixing and openness to the Gulf of Mexico leads to the high flushing rate of sediment and microplastics out of the bays. Larger microplastic particles (fragments: 178 ± 93 μm, fibers: 0.5 to 2.0 mm) were consistently deposited with finer sediments, indicating high transportability. Microplastic resuspension into bay waters has significant implications for limiting microplastic accumulation within bay sediments. This work provides a baseline for future studies quantifying the roles of wind and residence time on microplastics in coastal environments.

Accumulation of microplastics in various organs of fiddler crabs and sea cucumbers across the coastal habitats in Singapore

Microplastics (or MPs) are an emergent threat to marine organisms. This study assessed MP contamination in the major organs of four species from Singapore's coastal habitats: Orange Fiddler Crab (Gelasimus vocans) and Porcelain Fiddler Crab (Austruca annulipes) from mangroves, Garlic Bread Sea Cucumber (Holothuria scabra) from seagrass beds and Synaptid Sea Cucumber (Synaptula recta) from coral reefs. MPs were prevalent in all species and their organs. Mean MP concentrations in fiddler crabs were 6.63 ± 0.97 MP individual-1 in G. vocans and 12.18 ± 3.38 MP individual-1 in A. annulipes, where their female crabs had significantly more MPs than males. This study also confirmed the translocation of MPs to the crabs' hepatopancreas, which had the highest MP concentrations compared to gills and digestive tracts. These observations suggest that the fiddler crabs' sexual dimorphism could influence feeding efficiency and behaviour. In contrast, the sea cucumbers had lower MP concentrations in their organs, where the average MP concentrations were 10.00 ± 2.32 MP individual-1 in H. scabra and 6.33 ± 0.69 MP individual-1 in S. recta. For H. scabra only, their respiratory trees showed the highest MP levels compared to their digestive tracts. Across the species, MPs were predominantly <1,000 μm in size, in fibre shape and polyethylene (PE). These findings provide critical baseline data on MP contamination across different organs in marine organisms, serving as proxies for MP pollution levels in the environment.

Liquid metasurface for size-independent detection of microplastics

Microplastics (MPs) are widely distributed in water, soil, and air, drawing a global concern as a cause of chronic diseases and immune system disruption. Though as one of the most promising techniques in MP detection, the surface-enhanced Raman scattering (SERS) is heavily dependent on the distribution of the "hot spots" and the size of MPs, known as "coffee ring effect" and "size effect" respectively, imposing major challenges in the quantitative detection of various sized MPs on conventional SERS substrates. Here we present a self-healing metasurface based on plasmonic nanoparticle (NP) array at the liquid-liquid interface (LLI) and air-liquid interface (ALI). The fluidic nature of the metasurface and the repulsive forces between NPs offer atomic-level flatness and uniform distribution for "hot spots". Additionally, MPs are dissolved in the oil phase, uniformly enriched in the form of polymer molecular chains on the liquid metasurface, irrespective of the size of the MPs. This molecular dispersity of the dissolved MPs enhances the overlap between the "hot spots" and scattering volume of MPs, significantly improving the intensity and reproducibility of SERS. The sensing platform is successfully applied in trace detections of various MPs (PS, PET, PMMA, and PC), and validated in real samples.

Detection and quantification of microplastics in endometrial polyps and their role in polyp formation

With the increasing use of plastics, microplastic (MPs) pollution has garnered significant attention in recent years. Endometrial polyps are prevalent gynecological conditions in women of childbearing age, which impair endometrial receptivity and contribute to female infertility. However, no studies have yet reported the exposure of endometrial polyps to MPs. This study employed pyrolysis-gas chromatography/mass spectrometry and laser direct infrared spectroscopy to detect and compare MPs between normal endometrium and endometrial polyps. Using Py-GC/MS, we identified three main MPs in 14 normal endometrial samples and 16 endometrial polyps. The average abundance of MPs in the endometrial polyp group was significantly higher than in the normal endometrium group. The respective average abundance of polyethylene (PE), polystyrene (PS), and polyvinyl chloride (PVC) in the polyp and normal endometrium groups was 13.66 ± 2.0 vs. 7.132 ± 0.78 μg/g (p = 0.0009), 94.81 ± 10.67 vs. 69.29 ± 6.93 μg/g, and 67.67 ± 11.02 vs. 56.35 ± 6.90 μg/g. LDIR analysis revealed 13 different types of MPs, with polymethylmethacrylate being the most prevalent. Moreover, we discovered that PS microspheres can promote the proliferation and migration of endometrial stromal cells through PI3K/AKT pathway, which may be a key factor in the formation of endometrial polyps. This study is the first to explore the presence of MPs in endometrial polyps, compare the differences in MPs content between normal endometrium and endometrial polyps, and clarify the potential connection between MPs exposure and the formation of endometrial polyps. Further research is required to explore additional potential insights.

Microplastics enhance the prevalence of antibiotic resistance genes in mariculture sediments by enriching host bacteria and promoting horizontal gene transfer

Microplastics (MPs) and antibiotic resistance genes (ARGs) pose significant challenges to the One Health framework due to their intricate and multifaceted ecological and environmental impacts. However, the understanding of how MP properties influence ARG prevalence in mariculture sediments remains limited. Herein, the polystyrene (PS) and polyvinyl chloride (PVC) MPs with different sizes (20-120 μm and 0.5-2.0 mm) were selected to evaluate their impacts and underlying mechanisms driving ARGs dissemination. The results showed that PS and PVC MPs increased the relative abundance of ARGs by 1.41-2.50-fold and 2.01-2.84-fold, respectively, compared with control, particularly high-risk genes. The polymer type effect was identified as more influential than the size effect in driving the sediment resistome evolution. PVC shifted the microbial community assembly from stochastic to deterministic processes, thus enriching ARG host pathogens. Furthermore, the highly hydrophobic PS not only recruited the host bacteria colonization but also facilitated ARG exchange within the plastisphere. The exogenous additives released by PVC (e.g., heavy metals, bisphenol A, and tridecyl ester) and the particles synergistically promoted ARG conjugative transfer by inducing oxidative stress and enhancing cell membrane permeability. These findings revealed how MPs characteristics facilitated the spread of ARGs in marine benthic ecosystems, underscoring the importance of mitigating MPs pollution to maintain mariculture ecosystem health, prevent zoonotic diseases, and balance global mariculture with ecological health.

Environmental Health and Safety Implications of the Interplay Between Microplastics and the Residing Biofilm

The increasing prevalence of microplastics in the environment has raised concerns about their potential environmental and health implications. Biofilms readily colonize microplastics upon their entry into the environment, altering their surface characteristics. While most studies have explored how biofilms influence the adsorption and transportation of other contaminants by microplastics, the reciprocal interplay between microplastics and biofilms and the resulting ecological risks remain understudied. This review comprehensively reviews the impact of microplastic properties on biofilm formation and composition, including the microbial community structure. We then explore the dynamic interactions between microplastics and biofilms, examining how biofilms alter the physicochemical properties, migration, and deposition of microplastics. Furthermore, we emphasize the potential of biofilm-colonized microplastics to influence the environmental fate of other pollutants. Lastly, we discuss how biofilm-microplastic interactions may modify the bioavailability, biotoxicity, and potential health implications of microplastics.

Biophysics-guided uncertainty-aware deep learning uncovers high-affinity plastic-binding peptides

Plastic pollution, particularly microplastics (MPs), poses a significant global threat to ecosystems and human health, necessitating innovative remediation strategies. Biocompatible and biodegradable plastic-binding peptides (PBPs) offer a potential solution through targeted adsorption and subsequent MP detection or removal from the environment. A challenge in discovering plastic-binding peptides is the vast combinatorial space of possible peptides (i.e., over 1015 for 12-mer peptides), which far exceeds the sample sizes typically reachable by experiments or biophysics-based computational methods. One step towards addressing this issue is to train deep learning models on experimental or biophysical datasets, permitting faster and cheaper evaluations of peptides. However, deep learning predictions are not always accurate, which could waste time and money due to synthesizing and evaluating false positives. Here, we resolve this issue by combining biophysical modeling data from Peptide Binder Design (PepBD) algorithm, the predictive power and uncertainty quantification of evidential deep learning, and metaheuristic search methods to identify high-affinity PBPs for several common plastics. Molecular dynamics simulations show that the discovered PBPs have greater median adsorption free energies for polyethylene (5%), polypropylene (18%), and polystyrene (34%) relative to PBPs previously designed by PepBD. The impact of including uncertainty quantification in peptide design is demonstrated by the increasing improvement in the median adsorption free energy with decreasing uncertainty. This robust framework accelerates peptide discovery, paving the way for effective, bio-inspired solutions to MP remediation.

The vertical transport and fate of MPs-oil composite pollutants in nearshore environment

MPs-oil composite pollutants interact with particles to form MPs-oil-particles aggregates (MOPAs) in nearshore environment. In this study, we investigated vertical transport and fate of MPs-oil composite pollutants mediated by particles under various time scales, proposed and elucidated associated mechanisms. Majority of MPs with -CH2 suspended in water columns and particles with Si-O and O-H adsorbed MPs-oil composite pollutants in sediment phase, which caused differences in morphology structure and composition. The MOPAs with spherical or irregular three-dimensional in water columns can transport to sediment phase, resulting in more than 79 % lamellar MOPAs and more than 63 % oil in sediment phase. Besides, we demonstrated that degraded small-sized MPs-oil composite pollutants can resuspend into water columns. The mass of n-alkanes in sediment phase (< 45 μg) was lower than in water columns (< 120 μg) during degradation process. More importantly, during the intermediate stage of degradation, the size of oil droplets on surface of MPs decreased and particles trapped them to sediment phase, resulting in a V-shaped curve of mass changes of C14-C35 in water columns. Our research fills the gap in the field of MPs-oil composite pollutants in water columns and sediment phase, which can provide theoretical support for their disposal.

The first report on emerged microplastics in deep-sea sediment: Insights from the Central Indian Ocean Basin

Microplastics (MPs, <5 mm) are widespread in coastal ecosystems and pose a growing global concern; however, their presence in deep-sea environments remains underexplored, especially in the Indian region. This study addresses this gap by providing the first comprehensive documentation of MPs in the Central Indian Ocean Basin (CIOB) at a depth of 5000 m, marking the initial effort to assess their presence and abundance in deep-sea core samples. The study investigated the MP concentration, composition and potential sources, revealing a size range between 10 μm and 4900 μm, with average abundances recorded at BC20 (10.2 ± 6.2 MPs/g), the PRZ (6.4 ± 5.0 MPs/g), and the IRZ (4.5 ± 0.8 MPs/g). Fibres constituted 54.9 % of the MPs, primarily blue, black, and red, and the predominant polymer was polyacetylene (50 %), followed by polyvinyl alcohol and polyvinyl chloride. These findings highlight the significant presence of MPs in the deep sea, underscoring the need for a better understanding of their transport and deposition mechanisms. This research is vital for shaping conservation strategies and policies aimed at mitigating MP pollution in marine ecosystems, emphasizing the urgency for further investigations in this region.

Microplastic distribution and composition in mudflat sediments and varnish clams (Nuttallia obscurata) at two estuaries of British Columbia, Canada: An assessment of potential anthropogenic sources

Widespread microplastic contamination affects the marine-coastal ecosystems in British Columbia, Canada. To understand the characteristics and spatial distribution of of microplastics (MPs), we compared the MPs in sediments (n = 159) and Varnish clams (Nuttallia obscurata; n = 160) collected from two estuarine ecosystems (Cowichan and K'ómoks) experiencing different anthropogenic impacts; primarily resource extraction (i.e., logging) at Cowichan and urban development at K'omoks. Our objective wasto determine the MP abundance levels in sediments and clams and infer possible sources of MPs at the two estuaries. Microplastic polymer type was confirmed through FTIR spectrometry. The average abundance of MPs in sediments were 14.37 ± 11.57 particles/kg in the Cowichan Estuary and 30.96 ± 14.58 particles/kg in the K'ómoks Estuary. Varnish clam samples contained average abundance of 3.62 ± 2.58 particles/g and 2.24 ± 1.96 particles/g in Cowichan and K'ómoks estuaries, respectively. The Cowichan Estuary's marine terminal and K'ómoks Marina were found to be hotspots for MPs, likely due to a combination of industrial and local sources. Fibers were the most common type of MPs found in both sediment (53.34 %) and clam samples (53.5 %) from Cowichan, as well as in clam samples in% K'ómoks, indicating a potential link to textile sources contributing to the widespread presence of MPs in the marine environment. There was no clear signal based on the primary use of the estuary. Polyethylene was the predominant polymer type of MPs found in sediment and clam samples at Cowichan, whereas Polyester was most common at K'ómoks. Our study revealed the ubiquitous nature of these emerging pollutants in the sensitive estuarine environments of BC, with implications for plastic waste management and the reduction of plastic pollution at the regional level.

Seabed microplastics in the European continental shelf: Unravelling physical and biological transport pathways and reciprocal fauna-Polymer relationships

Marine sediments are recognized as major sinks for microplastics, including remote areas which were previously considered "plastic-free". The understanding of microplastic dynamics in marine sediments is however limited due to the numerous pelagic and benthic pathways involved, and how these are influenced by physico-chemical interactions with the particles. European continental shelves border densely populated areas and face a high risk of microplastic contamination. In this study we quantified microplastics in soft-sediments of European coastal seas and characterized their polymer composition separating surface sediments from deeper layers. We then analyzed the influence of water column and sediment properties on spatial variability of seabed microplastics and investigated the relationship with macrofauna communities. A higher proportion of negatively buoyant polymers in surface sediments (0-1 cm) across stations was explained by seawater salinity and sediment microalgal detritus, highlighting the role of riverine input and possibly the formation of hetero-aggregates in defining polymer deposition. Additionally, we found that seawater temperature influenced polymer composition in deeper sediment layers (0-3 cm), likely together with biological activities performed by macrobenthos such as ingestion and burial. Finally, we demonstrate that seabed microplastics contribute to the spatial variability in macrobenthos, highlighting that marine ecosystem functioning effects of microplastic pollution are likely mediated via the benthos.

Methane seepage leads to a specific microplastic aging process in the simulated cold seep environment

Marine microplastics pose a significant threat to ecosystems, and deep-sea regions serve as critical sinks for these pollutants. Among these regions, cold seeps harbor relatively high concentrations of microplastics. However, research on the aging of microplastics under low-temperature, dark, methane-abundant, and high-pressure conditions remains limited. Seawater and sediment were collected from various Haima cold seepage sites to simulate seepage environments in 200-mL high-pressure reactors. Four types of microplastics at high concentrations (approximately 10 %) were cultured and monitored over two months to explore how they aged. The key findings are as follows: (1) Compared to areas of weak seepage, methane seepage accelerated microplastic aging, as evidenced by increased surface roughness, enhanced C-O and (CO)-O bond formation, increased microbial colonization, and reduced contact angles. (2) Microplastic aging is more pronounced in sediments than in seawater, with biodegradable polylactic acid (PLA) exhibiting the most significant aging characteristics and carbon contribution. (3) Aged microplastics induce greater disturbances in inorganic nutrient levels than in organic matter, impacting nitrogen cycle processes involving nitrate, nitrite, and ammonium. This study results reveal the fundamental aging characteristics of microplastics in extremely deep seas and highlight their potential ecological effects.

Microplastic occurrence and hydrodynamic-sedimentary driving effects in the Bohai Strait region of China

The ubiquity of microplastics in oceans has led to an increased interest in microplastics in society. The Bohai Strait is in a key position in the Yellow and Bohai Seas and plays a key role in the exchange of materials and environmental changes in these waters. In this study, seawater, surface sediments, and column sediments, were collected from the Bohai Strait region. Among all seawater samples, the abundance of microplastics in the Bohai Strait region ranged between 0.38 and 3.20 items/L, and that of microplastics in surface sediments was between 15.80 and 94.41 items/kg d.w.. The average microplastics abundance in columnar sediments was 72.62 ± 29.86 items/kg d.w., which provided key information on the spatial distribution of microplastics and sedimentation phenomena in the Bohai Strait region. The abundance of microplastics was higher in regions where currents flowed more slowly, which suggests that ocean currents exert a crucial effect on microplastic distribution. In addition, the abundance of microplastics in sediments showed a close relation to the deposition rate, which implies that the deposition rate contribute to the deposition process of microplastics on the seafloor. The type of microplastics in seawater influences the kind of microplastics in sediments, which further emphasizes the importance of microplastics in seawater during microplastic transport and the deposition process. The results of this research contribute to the in-depth understanding of the behavior and propagation pathways of microplastics in oceans and provide a valuable reference for the reduction of microplastic pollution.

Microplastics in Santos São Vicente estuarine - Hotspot in sediments caused by low energy hydrodynamic events in strongly populated areas

Microplastics (MPs) have emerged as a significant class of contaminants due to their widespread presence in various environmental compartments. The ingestion of these particles poses a risk to both human health and the local biota. The investigation of the Santos estuary reveals the abundance of microplastics in the mangrove sediment. The highest concentration was 62,850-93,050 MPs·kg-1dw, never seen before in Latin America coast. The region investigated is characterized for silting sites and low energy events, notably Rio dos Bugres, influenced by anthropic aspects, while the São Vicente e Santos channels prevail the high energy hydrodynamic regime. In consequence, the MPs are entrapped in the interior of the estuary, affecting drastically the biota of mangrove. Spectroscopic investigation identified: polymers, pigments, herbicide and additives. The hypothesis is that densely populated siltation areas combined with low-energy events serve along the estuary for MPs accumulation and hotspots formation.

Impacts of wind forcing on microplastics kinematic in a sensitive water area

Microplastics (MPs) have been found in different environmental department globally, and the threat to organisms posed by MPs is also widely recognized. Kinematic characteristics of low-density fiber MPs in Poyang Lake under different due-south wind were calculated by combining hydrodynamic model with particle tracking model in this study. Poyang Lake is divided into north lake and south lake for study based on its topographic and hydrodynamic characteristics, and the results are as follows: the critical wind speeds causing vertical mixing of MPs in the water column ranges from 6 to 9 m·s-1 in the north lake, while it is >9 m·s-1 in the south lake, and the MPs beaching rate decreases by 7.08 %/(m·s-1) as the due-south wind speed increases. The MPs speed is mainly affected by surface current, while the direction of the velocity is more affected by wind. The MPs velocity in the south lake is only 27.10 % of that in the north lake, and the direction is more dispersed, so the due-south wind concentrates the direction of MPs velocity more to the north in the south lake. The northern wards movement of MPs resulted in a noticeable decrease in FS in the south lake, with FS decreasing by 0.10 for every 1 m·s-1 increase in wind speed, and therefore, the due-south wind reduces the ecological risk posed by MPs through reducing the range of movement and retention time. However, since the FS in the north lake has been close to the minimum value of 1, the reduction of the FS is not significant, and the wind reduces the risk mainly by shortening the retention time of the MPs. Therefore, the ecological risk caused by MPs in Poyang Lake under no or weak wind conditions should be taken into consideration.

Polymer material biodegradation in the deep sea. A review

The phenomenon of marine plastic pollution is now well-established, with documented impacts on marine biodiversity and biogeochemical cycles. In order to mitigate this environmental impact, a significant amount of research has been conducted in recent years with the objective of developing biodegradable alternatives to conventional polymers and their composites in marine environments. The findings of this research significantly enhanced our understanding of biodegradation mechanisms and identified promising candidates. However, the majority of these studies have been conducted in coastal marine environments, which represent a minor component of the marine ecosystem. Recent models on the transport of plastic debris in the oceans indicate that deep-sea environments are likely to be the ultimate sink for a significant proportion of plastics entering the oceans. The aim of this review is to provide an overview of the processes of biodegradation of polymers in these deep-sea environments. The diversity and specific characteristics of these environments with respect to degradation mechanisms are discussed. While the majority of deep-sea conditions are not conducive to biodegradation, studies on organic falls (wood and whale carcasses) and a few investigations into materials previously shown to be biodegradable in coastal marine environments demonstrate mechanisms that are similar to those observed in shallow waters. Nevertheless, further research is necessary to reach definitive conclusions. It is essential to extend these studies to a broader range of deep-sea environments. Additionally, new methodologies that integrate microbiology and polymer science are required to accurately assess the process of assimilation of these materials in these environments.

Morphodynamics drive the transport and accumulation of anthropogenic microparticles in tropical coastal depositional systems in southeastern Brazil

A significant limitation in current coastal pollution research is that microplastics (<5 mm) comprise only a fraction of all anthropogenic microparticles (AMP, <5 mm) scale residues. Comprehensive AMP assessments, including those comprising semisynthetic, and modified natural compositions, are lacking. For instance, the accumulation of AMP in different coastal morphological features within a depositional system remains poorly known, fueling long-lasting debates about the distribution process of microparticles. Using a multi-proxy approach, we address mutual interactions between distinct surface morphologies (tidal flats, beaches, and foredunes) and transport and deposition dynamics of AMP. This issue was addressed by analyzing sediment and water samples collected at a marine protected area in the south coastal of São Paulo (Brazil). Here, we showed that AMP abundance in the tidal mudflat (18,500-20,500 particles/kg) was four times higher than in beach sands (4700-5900 particles/kg), while the lowest abundance was observed in foredune sands (4350 particles/kg). This can be attributed to the low-energy hydrodynamics of tidal flats associated with the cohesive behavior of muddy sediments, which consequently favor trapping and act as the main sink for AMP. Further, coastal processes (waves and currents) drive AMP onshore through sediment transport from the surfzone to the beach, from where the AMP becomes available for onshore eolian transport. Higher AMP abundance (85 particles/l) was observed in the marine water samples compared to the estuarine water samples (35 particles/l). Fibers <1 mm appeared as the predominant AMP in the sediment (99-100 %) and water (80-95 %) samples, primarily consisting of modified cellulose (73 %), dye signature only (16 %), and microplastics (11 %). Consequently, we argue that to fully comprehend the spatial distribution of AMP in coastal sediments and waters, it is crucial to analyze these microparticles from an integrated perspective, primarily considering the hydro-wind dynamics of different coastal morpho-sedimentary compartments combined with sediment grain size.

Bottom-Feeders Eat Their Fiber: Ingestion of Anthropogenic Microdebris by Antarctic Deep-Sea Invertebrates Depends on Feeding Ecology

Anthropogenic debris has been documented in Antarctica for the past 40 years. Upon breakdown, large pieces become microdebris, which reaches the seafloor through a variety of physical and biological processes. The Antarctic benthos, deeply reliant on sinking organic particles, is thus vulnerable to ingesting microdebris. By using benthic specimens sampled between 1986 and 2016 and deposited in biological collections, we provide the first record of microdebris in Southern Ocean deep-sea invertebrates. Specimens from 15 species (n = 169 organisms) had their gut content examined, with 13 species yielding microdebris in the shape of fibers (n = 85 fibers). The highest ingestion percentages were recorded in the sea cucumbers Heterocucumis steineni (100%), Molpadia violacea (83%) and Scotoplanes globosa (75%), and in the brittle star Amphioplus peregrinator (53%). Deposit- and suspension-feeding were the strategies which yielded the most fibers, accounting for 83.53% of particles. Seven fibers were identified as microplastics, composed of polyamide, polycarbonate, polyester, polyethylene terephthalate, polyisoprene and polysulfone. We also provide the earliest record of a microplastic in Antarctica, a polysulfone fiber ingested by a Boreomysis sp. mysid caught in 1986. The occurrence of fibers in the world's most remote continental margin renews concerns of pollution in seemingly isolated regions.

Enrichment of Persistent Organic Pollutants in Microplastics from Coastal Waters

Despite the adsorption of microplastics (MPs), the precise quantification of their concentrating effect on persistent organic pollutants (POPs) remains uncertain. Therefore, in this study, POPs in MPs, POPs in suspended particulate matter (SPM), and dissolved POPs in seawater were distinguished to quantify the enrichment factor (EF) for characterizing the concentrating effects of MPs and SPM on POPs. The results showed that the logarithm of EF (log EF) for POPs in MPs was 5.94 to 7.14. For POPs, the concentrating effect of MPs was 1 to 2 orders of magnitude greater than that of SPM. Moreover, for PCDD/Fs, PBDD/Fs, and PBDEs, the concentrating effect of MPs was roughly comparable to that of organic matter in SPM, while it was 1 to 2 orders of magnitude higher than that of organic matter for dioxin-like PCBs and PBBs. The MPs were prone to sorbing highly toxic POP congeners. When the logarithm of the n-octanol-water partition coefficient (log KOW) of POP homologues ranged from 5.5 to 8.25, the log EF for POP homologues in MPs approximately was between 5 and 7. The heterogeneous MPs from the field environment affected their capacity to sorb POPs, causing a nonsignificant correlation between the enrichment factor and log KOW.

Occurrence characteristics and ecological impact of agricultural soil microplastics in the Qinghai Tibetan Plateau, China

Plastic mulch is widely recognized as a significant contributor to microplastics (MPs) pollution in agricultural soil. However, its direct impact on remote areas with low population density remains uncertain due to multiple pollution sources. This study aims to investigate MPs pollution and its risks regarding agricultural soil in the Qinghai Tibetan Plateau (QTP) in China. The results revealed that soil samples from the study area exhibited a range of MPs abundance, varying from 16.67 to 950 items/kg, with the highest average abundance observed in Chengguan district (CG) soil samples (611.11 items/kg). Polyethylene terephthalate (PET), polypropylene (PP), and polyethylene (PE) were identified as the predominant components of MPs in farmland soil. Furthermore, significantly higher levels of MPs were found in the facility agriculture soil compared to the control soil. Diversity and risk of MPs in different regions and cultivation conditions were significantly different. According to the employed risk assessment models, agricultural soil demonstrated a relatively high polymer risk (47 % of areas classified as level III). In addition to being influenced by exogenous factors, the diversity of MPs also plays an intrinsic role in regulating the risk of MPs pollution. This study contributes to an enhanced comprehension of the issue of MPs pollution in QTP farmland soil, providing valuable empirical evidence and theoretical underpinning for the development of efficacious control strategies.

Microplastic pollution in marine sediments of the Antarctic coastal environment of Potter Cove and nearby areas (25 de Mayo/King George Island, South Shetlands)

Plastic contamination in the Southern Ocean is a growing issue. This study provides the first comprehensive analysis of marine microplastics (MPs) (0.1-5 mm) in surface sediments in Potter Cove and nearby areas around Argentina's Carlini station (25 de Mayo/King George Island, South Shetlands). Sediment samples from 31 sites (2020-2022) were collected to examine whether MP pollution originates from station activities or ocean currents. All samples contained MPs, averaging 0.18 ± 0.12 MPs/g of sediment, mainly microfibers (MFs) and irregular microfragments (MFRs) (0.11-6.23 mm) and irregular microfragments (MFRs) (0.09-4.57 mm). Infrared spectroscopy identified 13 polymer types, including cellulosic materials, polyester, and polyamide, with most MPs < 1 mm, showing aging signs, similar to laundry wear. This widespread distribution suggests contamination may stem from both local activities and external sources. Findings underscore the urgent need for MP pollution management and further research to identify sources and develop effective mitigation strategies.

Quantitative analysis of microplastics in beach sand via low-temperature solvent extraction and thermal degradation: Effects of particle size and sample depth

Quantifying trace levels of microplastics in complex environmental media remains a challenge. In this study, an approach combining field collection of samples from different depths, sample size fractionation, and plastic quantification via pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) was employed to identify and quantify microplastics at two public beaches along the northeast coast of the U.S. (Salisbury beach, MA and Hampton beach, NH). A simple sampling tool was used to collect beach sand from depth intervals of 0-5 cm and 5-10 cm, respectively. The samples were sieved to give three size fractions: coarse (>1.2 mm), intermediate (100 μm-1.2 mm), and fine (1.2 μm-100 μm) particles. Following density separation and wet peroxide oxidation, a low-temperature solvent extraction protocol involving 2-chlorophenol was used to extract polyester (PET), polystyrene (PS), polyamide (PA), and polyvinyl chloride (PVC). The extract was analyzed using Py-GC-MS for the respective polymers, while the solid residue was pyrolyzed separately for polyethylene (PE) and polypropylene (PP). The one-step solvent extraction method significantly simplified the sample matrix and improved the sensitivity of analysis. Among the samples, PET was detected in greater quantities in the fine fraction than in the intermediate size fraction, and PET fine particles were located predominantly in the surface sand. Similar to PET, PS was detected at higher mass concentrations in the fine particles in most samples. These results underscore the importance of beach environment for plastic fragmentation, where a combination of factors including UV irradiation, mechanical abrasion, and water exposure promote plastic breakdown. Surface accumulation of fine plastic particles may also be attributed to transport of microplastics through wind and tides. The proposed sample treatment and analysis methods may allow sensitive and quantitative measurements of size or depth-related distribution patterns of microplastics in complex environmental media.

Microplastics contamination and risk assessment in bivalves of economic importance from Beypore estuary, Southern India

Microplastics (MPs) are ubiquitous pollutant causing severe threat to the biotic and abiotic components of the coastal ecosystem. Accumulation of MPs in the commercially important bivalves Viz. Perna viridis (green mussel) and Meretrix casta (clam) collected from four different locations of Beypore estuary, Southern India was studied. The study focused on the accumulation, characteristics, diversity indices, and human health risk assessment of MPs in the bivalves of Beypore estuary. A total of 120 bivalve samples were examined for the MPs contamination. Whole tissue digestion method using 10% KOH was employed to retrieve the MP content. The results indicate that the average abundance of MPs in Perna viridis is 2.38 ± 1.56 MPs/individual and 0.15 ± 0.09 MP/g/wet weight whereas, for Meretrix casta it is 1.35 ± 1.02 MPs/individual and 0.3 ± 0.27 MP/g/wet weight. Spearman's correlation reveals that there is no significant correlation observed between the abundance of MPs in the bivalves with their morphomertric parameters. The characteristics of MPs in the bivalves are dominated by translucent colored particles (88.95%) in the form of films (45.13%) and fibers (33.6%) having a size ranged between 300 and 1000 μm (51.13%) and composed of polyethylene (54.5%) and polypropylene (20%) polymers. The microplastic index in Meretrix casta ranged between 0.02 and 0.07 whereas for Perna viridis it ranged between 0.08 and 0.10 indicating minimal to moderate MPs contamination. The microplastics diversity integrated index ranged between 0.67 and 0.69 for Meretrix casta whereas, for Perna viridis the value ranged between 0.34 and 0.60 suggests moderate diversity of MPs derived from multiple sources. Based on polymer hazard index, the potential health risk was assessed with a hazard level ranged between II and IV suggesting significant health risk. Systematic monitoring of MPs at river basin scale along with stringent plastic waste management is required to minimize plastic pollution load into the river system.

Quantifying microplastics in sediments of Jinzhou Bay, China: Characterization and ecological risk with a focus on small sizes

Small-sized microplastics (MPs) pose greater ecological toxicity due to their larger surface area, which makes them more likely to act as carriers for other pollutants and to be ingested by aquatic organisms. However, traditional visual analysis often neglects small-sized MPs and their associated ecological risk. This study utilized Laser Direct Infrared (LDIR) spectroscopy and traditional visual analysis to examine MPs in 31 sediment samples from Jinzhou Bay, a typical semi-enclosed bay located at the economic center of Dalian, China. The results showed significant heterogeneity in MP distribution, with averages of 1192 and 2361 items/kg dry weight reported by visual analysis and LDIR spectroscopy, respectively. LDIR spectroscopy identified MPs as small as 10 μm, with the majority of MPs (89.21 %) within the 10-250 μm range, and a significant proportion (46.45 %) between 10 and 50 μm among them. However, visual analysis was limited to detecting MPs >50 μm, and significant portions were identified between 50 and 100 μm (49.36 %) and 100-250 μm (31.01 %), missing a substantial fraction of smaller MPs. The predominant polymers identified were polyamide (PA), polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), and acrylonitrile butadiene styrene (ABS). LDIR spectroscopy demonstrated a strong positive correlation between MP abundance and clay content, a relationship not observed with traditional visual analysis. The Potential Ecological Risk Index (PERI) indicated that over 87 % of sites posed an extremely high risk according to LDIR spectroscopy, compared to 51 % by traditional visual analysis. These discrepancy underscores the underestimation of ecological risks by traditional methods, particularly for small-sized MPs. High-risk polymers such as polyvinyl chloride (PVC), ABS, and polyurethane (PUR) significantly influenced PERI values. These findings highlight the critical need for precise identification and thorough risk assessment of small-sized MPs in environmental studies and offer insights for understanding of MP vertical migration in aquatic environments, particularly in the context of co-settlement with sediments.

Potential toxicity of microplastics on vertebrate liver: A systematic review and meta-analysis

Microplastics (MPs) pollution is emerging as a significant environmental concern, threatening human and animal health. Liver, as an important organ, plays an important role in the metabolism and detoxification of pollutants. Many studies have suggested that the liver is a potential target organ for MPs. However, the extent and consequences of the impacts of MPs on the liver reported in studies remain inconsistent. We categorized vertebrates into fish, mammals, and birds and performed a meta-analysis to comprehensively examine the effects of MPs on the liver. Hedges' g values were calculated to evaluate effect sizes. To further explore the sources of heterogeneity among the studies, we conducted subgroup analyses focusing on life stage, MPs type, MPs size, and exposure duration. Additionally, we normalized the MPs concentrations and conducted meta-regression analyses to explore the relationship between MPs concentrations and their hepatotoxic effects. A total of 118 studies were included in this meta-analysis. By quantifying 19 indicators, the results showed that MPs could damage the liver by altering liver morphology, inducing oxidative stress, producing intracellular toxicity, altering biotransformation processes, and disturbing lipid metabolism. Intracellular toxicity, followed by oxidative stress, had the greatest impact. Organisms are more sensitive to MPs under the following conditions: longer exposure duration, smaller MPs sizes, and earlier life stages. As the concentration of MPs increases, the levels of several liver indicators, including catalase, glutathione S-transferase, reactive oxygen species, and alkaline phosphatase, progressively increase. This study provides a comprehensive understanding of the effects of MPs on the liver and suggests the underlying mechanisms of MPs hepatotoxicity.