High Abundances of Microplastic Pollution in Deep-Sea Sediments: Evidence from Antarctica and the Southern Ocean

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.

Adsorption kinetics of different mercury species on three kinds of micro-/nano-plastics in micro-polluted aquatic environments and their combined toxicity

The contamination of micro-plastics (MPs)/nano-plastics (NPs) in environment poses a global concern, necessitating a scientific evaluation of their potential risks to ecosystems and organisms. We herein investigated the adsorption kinetics of different mercury species including inorganic mercury (Hg2+), methylmercury (MeHg) and ethylmercury (EtHg) on three different MPs, such as polyethylene MPs (PE MPs), polypropylene MPs (PP MPs) and polystyrene MPs (PS MPs) in micro-polluted water in detail, and further evaluated the individual and combined cytotoxicity of polystyrene NPs (PS NPs)/polypropylene NPs (PP NPs) and different mercury species. The results indicated that EtHg undergoes demethylation partly to form Hg2+ during the adsorption process on PP MPs, and the adsorption kinetics of Hg2+, MeHg and EtHg on three MPs fitted with pseudo-first-order (PFO) model in initial stage and simultaneously fitted with pseudo-second-order (PSO) model during whole adsorption process. This suggested that adsorption of mercury species on three MPs we driven mainly by physical process in initial stage and by chemical process during whole absorption process. In natural micro-polluted water, the equilibrium adsorption capacities (Qe) of Hg2+ on three MPs (156.3-270.3 ng/g) are much higher than that of MeHg (5.562-78.13 ng/g) and EtHg (7.831-70.42 ng/g). Cytotoxicity experiments revealed that PP NPs and PS NPs themselves have little cytotoxicity, but the presence of them can enhance the cytotoxicity of mercury species, showing NPs size-depended and mercury species-depended synergistic toxic effect. The findings of this study provided valuable insights for scientifically evaluating the potential risk of MPs/NPs to ecosystems and organisms.

Robust polyaniline coating magnetic biochar nanoparticles for fast and wide pH and temperature range removal of nanoplastics and achieving label free detection

Nanoplastics as an emerging pollutant are ubiquitous in water and still not easy to measure and remove. In this regard, polyaniline coating magnetic biochar nanoparticles constructed by pyrolysis of ferrate pretreated bagasse and ball milling and coating surface with polyaniline (PA@MBCBM) were tested for their capability to attach and remove polystyrene nanoplastics in water. Porousness and rich functional groups and positive charging property of PA@MBCBM was responsible for fast, high capacity and robust attaching of nanoplastics. 94.9 % - 99.0 % of nanoplastics were removed at wide range of pH conditions (1 - 10) and PA@MBCBM was reusable for seven times with less changing of performance, and maximum adsorption capacities reached 276.24 - 334.45 mg/g at both cold and warm temperatures (5 - 35 °C). Moreover, taking advantages of efficient nanoplastics adhesion, high conductivity and electrochemical activity, the PA@MBCBM, was tested to fabricate a label free screen-printed electrode for nanoplastics detection, and achieved reasonable sensitivity with the lowest detection limit being 1.26 μg/L. In addition, exceptional performances of adsorption and detection in real water samples were also successfully realized. The proposed PA@MBCBM having dual function of robust and efficient adsorption removal, and label free and sensitive determination of nanoplastics, would be greatly constructive for reliable, cost effective and effective control and monitoring of the nanoplastics contamination.

Polystyrene microplastics and cypermethrin exposure interfered the complexity of antibiotic resistance genes and induced metabolic dysfunction in the gut of adult zebrafish

Environmental pollutants such as microplastics (MPs) and pesticides are becoming prevalent in aquatic ecosystems, posing risks to wildlife and human health. This study investigated the toxicological effects of polystyrene microplastics (PS-MPs) and cypermethrin (CYP) on adult female zebrafish (Danio rerio), focusing on intestinal microenvironment. Adsorption kinetics experimental results showed that PS-MPs can adsorb a certain amount of CYP on its surface, thereby forming a new type of composite pollutant. After exposure to red fluorescent PS-MPs for 4 days, it was found that the PS-MPs could enter the zebrafish and accumulate in the intestines. Five-month-old female zebrafish were exposed to PS-MPs, CYP, and a mixture of both for 21 days. After exposure, feces were collected and analyzed using metagenomic sequencing to determine microbial composition and functional changes. Metagenomic sequencing of naturally excreted feces showed that co-exposure synergistically reduced α-diversity and shifted community structure, with marked losses of beneficial Fusobacteriota, Firmicutes and Cetobacterium somerae and enrichment of pathogenic Preplasmiviricota. Functional annotation indicated that PS-MPs alone up-regulated glycoside hydrolases and glycosyl-transferases, whereas CYP and the co-exposure group suppressed a great number of the top 50 carbohydrate-active enzymes and decreased secondary metabolic pathways linked to amino-acid, lipid and carbohydrate metabolism pathways. Antibiotic-resistance gene (ARGs) profiling identified 57 ARG types (such as sul1, adeF, lnuC and mphA) after co-exposure. Finally, key genes related to amino acid metabolism, carbohydrate metabolism, and lipid metabolism in intestinal tissue were significantly altered. Collectively, our data demonstrated that PS-MPs and CYP exposure amplified gut dysbiosis, metabolic dysfunction and ARG complexity in zebrafish. Overall, the study highlighted the potential risks of combined environmental pollutants on intestinal microbiota, with implications for ecosystem health.

Effect of Acrylonitrile Butadiene Styrene (ABS) Secondary Microplastics on the Demography of Moina macrocopa (Cladocera)

Microplastics (MPs) are emerging pollutants that are ubiquitous in aquatic ecosystems and can affect the stability of aquatic food webs. They are intentionally produced in a size of less than 5 mm for specific purposes or are the result of the fragmentation of larger plastic debris. Zooplankton can be affected directly by the ingestion of MPs or indirectly by interference caused by suspended plastic particles. Various environmental agencies recommend the genus Moina for assessing risk from water pollutants. However, this genus has received less attention in research compared to non-indigenous cladocerans commonly used as test organisms. We evaluated the effects of artificially fragmented acrylonitrile butadiene styrene microplastics (ABS-MPs) on key demographic parameters such as survival, mortality, life expectancy, fecundity, and feeding rates of Moina macrocopa americana. We exposed M. macrocopa neonates to a diet consisting of the green microalgae Chlorella vulgaris and ABS-MP particles. Four treatments were set with different concentrations of ABS-MP particles (5, 10, and 20 mg L-1). Survivorship, mortality, and reproduction were recorded daily until the last individual from the original cohort died. ABS-MPs significantly reduced M. macrocopa consumption rates of C. vulgaris, with an 85% decrease compared to the control. Although no statistically significant differences were found in life expectancy, net reproduction, or generation time among the toxic treatments, these parameters were drastically reduced compared to the control, even at the lowest concentration (5 mg L-1); this resulted in a 34% reduction in average lifespan. The ABS-MPs interfere with the long-term population dynamics of M. macrocopa and change their consumption rates, potentially decreasing their fitness.

Micro- and Nanoplastics and Fetal Health: Challenges in Assessment and Evidence from Epidemiological Studies

The usage of plastics in life and industrial applications has led to global environmental pollution by micro- and nanoplastics (MPs/NPs). Despite their widespread occurrence in the environment, little is known about their presence in humans and the potential implications for human health, particularly maternal and fetal health during the prenatal and neonatal periods. Studies on experimental animals indicate that exposure to MPs/NPs can lead to neurological abnormalities in offspring and hemodynamic alterations in the placenta and fetal cerebral arteries. These findings underscore the need for further epidemiological studies that examine the effects of MPs/NPs on fetal health during pregnancy, a critical period for neurological development. This review summarizes the existing knowledge on the effects of prenatal exposure to MPs/NPs on fetal development and birth outcomes in humans and provides a detailed overview of the challenges encountered in contamination prevention, quality assurance and quality control in analytical procedures. It also discusses the sampling and digestion methods used for the extraction of MPs/NPs from biological samples of maternal and fetal origin, highlighting the difficulties associated with accurately quantifying these particles in complex biological matrices, identifying the gaps in current research, and suggesting recommendations to improve methodologies for assessing the risks associated with prenatal MP/NP exposure.

Propionic acid/FBP1 is involved in polystyrene nanoplastic-induced cardiac injury via the gut-heart axis

BACKGROUND

Micro-/nanoplastics (MNPLs) are widely found in the environment and have toxic effects on various organs and systems. However, the role of the gut-cardiac axis in cardiotoxicity induced by MNPLs has not yet been elucidated through research.

RESULTS

In this study, we examined the effects of 80 nm polystyrene nanoplastics (PS-NPs) on the heart and human cardiomyocytes (AC16) cells. Histopathological examination showed that NPs caused impaired cardiac function and increased myocardial collagen deposition. In view of the potential influence of gut microbiota and its metabolites on cardiac function, we conduct this study to investigate the specific effects they have on cardiac function. Analysis of cecal contents by 16 s ribosomal RNA (rRNA) and short chain fatty acids (SCFAs) revealed that colonic tissue damage, intestinal flora disorder, and reduction of propionic acid induced by PS-MPs were closely related to cardiac function. Further transcriptomic analysis of heart and colon tissues indicated that propionic acid may reduce cardiac function by reducing the expression of fructose-1, 6-biphosphatase 1 (FBP1). The hypothesis was further verified by in vitro intervention experiments with sodium propionate and FBP1 activator (BML-275).

CONCLUSIONS

In summary, our study systematically demonstrated the role of gut-heart axis in NPs-induced cardiac injury, and the specific process was that NPs exposure reduced propionate level, which in turn inhibited FBP1 expression to impair cardiac function. These findings provide new insights into NPs-induced cardiotoxicity and identifie potential therapeutic targets, providing clues for the prevention and treatment of NPs-induced cardiac injury in the future.

Microplastic distribution and its implications for human health through marine environments

Microplastics are pervasive pollutants in the ocean, threatening ecosystems and human health through bioaccumulation and toxicological effects. This review synthesizes recent findings on microplastic distribution, trophic transfer, and human health impacts. Key findings indicate that microplastic abundance is highest in the Indian and Pacific Oceans, particularly in seawater and sediment. Morphologically, fibers and fragments dominate, with polypropylene, polyethylene, and polyester being the most prevalent polymers. Smaller particles (<1 mm) undergo long-range transport via ocean currents, while biofouling accelerates vertical sinking. Trophic transfer studies confirm microplastic ingestion across marine food webs. Human exposure is associated with seafood consumption, inhalation of airborne particles, and potential dermal contact, particularly in marine environments. These exposures can lead to adverse health effects, including inflammation, organ damage, respiratory issues, oxidative stress, and metabolic disruptions. Finally, this review explores potential strategies for minimizing human exposure to microplastic pollution in marine environments, paving the way for further research in this critical area.

Decoding the Plastic Patch: Exploring the Global Microplastic Distribution in the Surface Layers of Marine Regions with Interpretable Machine Learning

The marine environment is grappling with microplastic (MP) pollution, necessitating an understanding of its distribution patterns, influencing factors, and potential ecological risks. However, the vast area of the ocean and budgetary constraints make conducting comprehensive surveys to assess MP pollution impractical. Interpretable machine learning (ML) offers an effective solution. Herein, we used four ML algorithms based on MP data calibrated to the size range of 20-5000 μm and considered various factors to construct a robust predictive ML model of marine MP distribution. Interpretation of the ML model indicated that biogeochemical and anthropogenic factors substantially influence global marine MP pollution, while atmospheric and physical factors exert lesser effects. However, the extent of the influence of each factor may vary within specific marine regions and their underlying mechanisms may differ across regions. The predicted results indicated that the global marine MP concentrations ranged from 0.176 to 27.055 particles/m3 and that MPs in the 20-5000-μm size range did not pose a potential ecological risk. The interpretable ML framework developed in this study covered MP data preprocessing, MP distribution prediction, and interpretation of the influencing factors of MPs, providing an essential reference for marine MP pollution management and decision making.

Assessing microplastic and nanoplastic contamination in bird lungs: evidence of ecological risks and bioindicator potential

Microplastics (MPs, 1 µm-5 mm) and nanoplastics (NPs, < 1 µm), collectively termed micro(nano)plastics (MNPs), are pervasive airborne pollutants with significant ecological risks. Birds, recognized as bioindicators, are particularly vulnerable to MNP exposure, yet the extent and risks of MNP pollution in bird lungs remain largely unexplored. This study assessed MP exposure in bird lungs of 51 species and NP exposure in the lungs of five representative species using laser direct infrared (LDIR) and pyrolysis gas chromatography-mass spectrometry (Py-GC-MS) techniques, respectively. The LDIR analysis revealed different degrees of MP contamination in bird lungs, with an average abundance of 221.20 items per species and 416.22 MP particles per gram of lung. Among 32 identified MP types, chlorinated polyethylene (CPE) and butadiene rubber (BR) predominated, with particles primarily in film and pellet forms, concentrated in the 20-50 μm size range. The polymer hazard index (PHI) indicated elevated ecological risks (levels Ⅲ or Ⅳ) in most bird lungs. Py-GC-MS detected nylon 66 (PA66), polyvinyl chloride (PVC), and polypropylene (PP) NPs at varying concentrations. Terrestrial, carnivorous, and larger-bodied birds exhibited higher MNP burdens. This study provides the first evidence of MNP contamination in bird lungs, highlighting their potential as bioindicators of airborne MNP pollution.

Cascading tipping points of Antarctica and the Southern Ocean

Antarctica and the Southern Ocean are key elements in the physical and biological Earth system. Human-induced climate change, and other human activities in the region, are leading to several potential interacting tipping points with major and irreversible consequences. Here, we examine eight potential physical, biological, chemical, and social Antarctic tipping points. These include ice sheets, ocean acidification, ocean circulation, species redistribution, invasive species, permafrost melting, local pollution, and the Antarctic Treaty System. We discuss the nature of each potential tipping point, its control variables, thresholds, timescales, and impacts, and focus on the potential for cumulative and cascading effects as a result of their interactions. The analysis provides substantial evidence of the need for more concerted and rapid action to limit climate change and to minimise the impacts of local human activities to avoid these cascading tipping points.

Microplastics in freshwater and marine ecosystems: Occurrence, characterization, sources, distribution dynamics, fate, transport processes, potential mitigation strategies, and policy interventions

Most of the literature on microplastics (MPs) focuses on freshwater or terrestrial ecosystems, frequently overlooking their interconnections with the marine environments. This oversight is worrying given that both ecosystems serve as primary pathways for the introduction of MPs into marine environments. This review synthesizes existing literature on MPs in both freshwater and marine ecosystems across all six continents. The most commonly produced plastic polymers in industry are polyethylene (36 %) and polypropylene (21 %), and studies revealed that these two materials are the most abundant in aquatic ecosystems. Primary and secondary MPs originate from a range of sources including land-based disposal, the ocean, airborne deposition, wastewater treatment facilities, automobiles, pharmaceuticals and personal care products, synthetic textiles, and insect repellents. Notably, secondary MPs, which are formed from the breakdown of larger plastic items comprise approximately 69-81% of marine debris, especially in urbanized, densely populated areas. The inconsistencies of the methodologies (sampling, extraction, and quantification) and the units employed for result presentations are part of the major limitations in MPs research. Environmental phenomena such as heteroaggregation, weathering, adsorption, leaching, and fragmentation are the major factors influencing the behavior, fate, and degradation process of plastic particles. The physicochemical properties of plastic polymers, such as density, crystallinity, as well as bioturbation, meteorological forces, and wind actions, including currents, waves, and tides, are responsible for biofouling, aggregation, sinking into the bottom sediment, resuspension, and the vertical, horizontal, and spatiotemporal distributions and transport of MPs. The potential solutions to mitigate plastic pollution are grounded in the 3Rs framework, which includes reducing production and consumption, advancing the biotechnological, chemical and microbial development of degradable polymers, promoting reusable plastic products with lower environmental impacts over their lifetimes, and recycling waste into new products. The regulatory policies on single-use plastics commonly involve permanent bans and financial penalties for violators. In addition, nations such as the United States, the Netherlands, and northern Europe have introduced economic incentives to encourage the return of reusable materials to reduce plastic waste and the resulting envrionmental pollution.

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.

Fate, source, and ecological risk of microplastic in the surface sediment of the Beibu Gulf, the Northern South China sea

A large-scale investigation of the surface sediments in the Beibu Gulf was conducted in this study to reveal the contamination characteristics of microplastics in the surface sediments of the Beibu Gulf. The results showed that the abundance of microplastics ranged from 12.91 to 251.69 items/kg, dry weigh (DW), with an average abundance of 84.34 ± 51.85 items/kg (DW). The highest abundance of microplastics was found in the estuary of northwestern Hainan, influenced by the West Guangdong Coastal Current. The overall distribution of abundance showed a decreasing trend from nearshore to offshore. Microplastics in the surface sediments were predominantly in the form of fiber (87.51%), with a predominant white color. The polymer of microplastics in surface sediment was primarily polyester (43.43%). The main sources of microplastics include household items, textile products, food packaging, fishing activities, industrial activities, sewage discharges, and biochemical materials, of which household products and textile products are the most important sources. The results of the risk evaluation showed that the sediment of Beibu Gulf was contaminated with microplastics (pollution load index >1) and the polymer risk was at low to extremely high levels. The high abundance of microplastics and highly toxic polymers resulted in increased ecological risk. These findings highlight the urgent need to implement timely and effective measures to reduce the impact of intensive human activities on microplastic pollution. At the same time, the study data provide an important reference for future ecotoxicological investigations, pollution management strategies and microplastic policy development.

Revealing Microplastic risks in stratified water columns of the East China Sea offshore

Microplastics have been proven to impact a broad range of marine species significantly. This study investigated the vertical distribution characteristics of microplastics (MPs) to verify their potential toxicity, distribution patterns, and affecting probability on organisms offshore of the East China Sea (ECS), China. Significant variations in MP characteristics across stratified water layers were identified and corroborated through artificial neural network (ANN) analysis. By a combination of species sensitivity distribution (SSD), risk quotient (RQ) and joint probability curves (JPC) method, this study gave the regional risk thresholds and current risk distributions. Based on SSD, the derived predicted no-effect concentration for the ecosystem was 52.0 items/L (95 % confidence interval: 13.7-262.8 items/L), with the 5 % species hazardous concentration at 103.6 items/L. The RQ assessment results indicated varying ecological risk levels across different water layers, with the highest risks transitioning from north to south and from surface to bottom layers. Most sites exhibited a moderate risk level, with the highest risks identified in surface water near the Yangtze River Estuary, China. Conversely, the JPC analysis suggested a minimal ecological risk across the study area, emphasizing variable ecological risk contingent on species presence. This study underscores the importance of examining surface and intermediate water layers for marine habitats and organisms, highlighting the necessity of prioritizing investigations into the distribution of MPs across different water layers in the ECS, particularly focusing on buoyant polyester fibers present in the upper water column and the layers beneath the offshore surface.

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.

Experimental ingestion of microplastics in three common Antarctic benthic species

Microplastics (MP) have spread to every corner of the globe, reaching remote areas like Antarctica. Recent studies detected MP in marine environments, including biota. Benthic organisms suffer negative effects upon MP ingestion, leading to impacts on their populations. To address the current knowledge gap on how Antarctic benthic invertebrates interact with MP, we conducted an experiment exposing a bivalve (Aequiyoldia eightsii) and two ascidians (Cnemidocarpa verrucosa and Molgula pedunculata) to polyethylene microbeads (mb). Specimens of each species were exposed for 48 h to two different concentrations of microbeads, a low dose (100 mb/l) and a high dose (1000 mb/l), with the same proportion of four different microbead size fractions (Fine (10-20 μm), Small (45-53 μm), Medium (106-125 μm), and Large (850-1000 μm)). After exposure, all three species had ingested microbeads. Significant differences between doses were observed in A. eightsii and C. verrucosa but not in M. pedunculata. Both ascidians ingested microbeads of all size fractions, whereas the bivalve did not ingest the largest microbeads. No significant differences were found between species in the number nor sizes of microbeads ingested. Minor variations between taxa may be attributed to the specific biology and anatomy of each species. Our study highlights the need for a deeper understanding of Antarctic benthic ecosystems, suggesting that the interaction with MP is species-specific. We believe that this study provides a baseline for assessing MP pollution in Antarctic benthic invertebrates and will help to inform policy-makers in protecting and preserving Antarctic marine ecosystems from MP pollution.

Microplastics influencing aquatic environment and human health: A review of source, determination, distribution, removal, degradation, management strategy and future perspective

Microplastics (MPs) are produced from various primary and secondary sources and pose multifaceted environmental problems. They are of non-biodegradable nature and may stay in aquatic environments for a long time period. The present review has covered novel aspects pertaining to MPs that were not covered in earlier studies. It has been observed that several methods are being employed for samples collection, extraction and identification of MPs and polymer types using various equipment, chemicals and instrumental techniques. Aquatic species mistakenly ingest MPs, considering them prey and through food-chain, and then suffer from various metabolic disorders. The consumption of seafood and fish may consequently cause health implications in humans. Certain plasticizers are added during manufacturing to provide colour, durability, flexibility, and strength to plastics, but they leach out during usage, storage, and transport, as well as after entering the bodies of aquatic species and human beings. The leached chemicals (bisphenol-A, triclosan, phthalates, etc.) act as endocrine disrupting chemicals (EDCs), which effect on homeostasis; thereby causing neurotoxicity, cytotoxicity, reproductive problems, adverse behaviour and autism. Negative influence of MPs on carbon sequestration potential of water bodies is also observed, however more studies are required to understand it with a detail mechanism under natural conditions. The wastewater treatment plants are found to remove a large amount of MPs, but in turn, also act as significant sources of their release in sludge and effluents. Further, it is covered that how advanced oxidation processes, thermal- and photo-oxidation, fungi, algae and microbes degrade the plastics and increase their numbers in the surrounding environment. The management strategy comprising recovery of energy and other valuable by-products from plastic wastes, recycling and regulatory framework; are also described in detail. The future perspectives can be of paramount importance to control MPs generation and their abundance in the aquatic and other types of environments. The studies in future need to focus on advanced filtration techniques, advanced oxidation processes, energy recovery from plastic wastes and influences of MPs on carbon sequestration in aquatic environment and human health.

Microplastic pollution in the marine environment: Distribution factors and mitigation strategies in different oceans

As the COVID-19 pandemic began in 2020, plastic usage spiked, and microplastic (MP) generation has increased dramatically. It is documented that MP can transfer from the source to the ocean environment where they accumulate as the destination. Therefore, it is essential to understand their transferring pathways and effective environmental factors to determine the distribution of MPs in the marine environment. This article reviews the environmental factors that affect MP distribution in the oceans including abiotic such as ocean currents and wind direction, physical/chemical and biological reactions of MPs, natural sinking, particle size and settling velocity, and biotic including biofouling, and incorporation in fecal material. It was found that velocity and physical shearing are the most important parameters for MP accumulation in the deep ocean. Besides, this review proposes different research-based, national-level, and global-level strategies for the mitigation of MPs after the pandemic. Based on the findings, the level of MP pollution in the oceans is directly correlated to coastal areas with high populations, particularly in African and Asian countries. Future studies should focus on establishing predictive models based on the movement and distribution of MPs to mitigate the levels of pollution.

Environmental impact of microplastics and potential health hazards

Microscopic plastic (microplastic) pollutants threaten the earth's biodiversity and ecosystems. As a result of the progressive fragmentation of oversized plastic containers and products or manufacturing in small sizes, microplastics (particles of a diameter of 5 mm with no lower limit) are used in medicines, personal care products, and industry. The incidence of microplastics is found everywhere in the air, marine waters, land, and even food that humans and animals consume. One of the greatest concerns is the permanent damage that is created by plastic waste to our fragile ecosystem. The impossibility of the complete removal of all microplastic contamination from the oceans is one of the principal tasks of our governing body, research scientists, and individuals. Implementing the necessary measures to reduce the levels of plastic consumption is the only way to protect our environment. Cutting off the plastic flow is the key remedy to reducing waste and pollution, and such an approach could show immense significance. This review offers a comprehensive exploration of the various aspects of microplastics, encompassing their composition, types, properties, origins, health risks, and environmental impacts. Furthermore, it delves into strategies for comprehending the dynamics of microplastics within oceanic ecosystems, with a focus on averting their integration into every tier of the food chain.

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.

The combined effects of microplastics and their additives on mangrove system: From the sinks to the sources of carbon

Mangrove ecosystems, a type of blue carbon ecosystems (BCEs), are vital to the global carbon cycle. However, the combined effects of microplastics (MPs) and plastic additives on carbon sequestration (CS) in mangroves remain unclear. Here, we comprehensively review the sources, occurrence, and environmental behaviors of MPs and representative plastic additives in mangrove ecosystems, including flame retardants, such as polybrominated diphenyl ethers (PBDEs), and plasticizers, such as phthalate esters (PAEs). Mangrove ecosystems have a complex influence on the behaviors of MPs and additives. Under the action of natural and unnatural factors, these pollutants exhibit complex behaviors including migration, interception, deposition and transformation, that are closely linked to those of particulate carbon, particularly carbon sequestration processes. MPs and additives hinder the CS function of mangroves by harming the growth of flora and fauna, influencing microbial nitrogen and sulfur cycles, and enhancing the degradation of organic matter in the sediment. The increasing accumulation and widespread occurrence of MPs and additives will greatly influence the carbon cycle. Future work is encouraged on systematic investigation of new alternatives to plastics and additives, and research methods to uncover the impact mechanisms of MPs and additives on BCEs. The developments of management measures and engineering technologies are also required to enhance pollutant control and mangrove CS.

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.

Optimising microplastic polyethylene terephthalate fibre extraction from sediments: Tailoring a density-separation procedure for enhanced recovery and reliability

Despite the presence of microplastics in sediments being widely acknowledged, the absence of standardised processing methods in extracting microplastics can compromise reliable and comparable results. Density separation is a predominant method for extracting microplastics from sediments. In this study, Sodium Polytungstate (ρ = 1.6 g cm-3) was selected as the density separation agent for three key factors: i) optimal density for extracting common plastic polymers, ii) low toxicity, and iii) recycling potential of the solution. It is therefore cost-effective, and the risk of solution dispersal is minimal. The solution was tested through four separation procedures, extracting PET fibres from three artificial sediment mixtures (i.e., pure sand, pure mud, and 50 % sand and 50 % mud). The results indicate that the solution employed in this work is highly effective for extracting microplastic fibres from sediments, with recovery rates up to 99 %. However, the results highlight differences in the recovery among the four procedures and in terms of the sediment characteristics. Specifically, extracting microplastics was easier in sandy sediment samples than in mud-rich ones. The complexity of extracting microplastics from mud-rich sediments results from i) the creation of microplastic-sediment aggregates forming denser structures, that settle down trapping microplastics in sediments; ii) the development of a clay sediment cap that hinders the rise of microplastics to the surface. Reducing the risk of underestimation of microplastic content in mud-rich samples can be accomplished by applying a procedure that involves placing the samples with the Sodium Polytungstate solution on a stirring plate while progressively lowering the rotation velocity. Using this method, cohesive sediments lose their ability to trap microplastics while aggregating, consequently reducing their ability to drag microplastics to the bottom. This facilitated microplastics to reach the liquid surface, thereby enabling an efficient retrieval even in mud-rich samples.

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.

Co-exposure of microplastics with heavy metals increases environmental pressure in the endangered and rare wildlife reserve: A case study of the zhalong wetland red-crowned crane nature reserve, northeast China

Microplastics (MPs) exposure to remote areas, including endangered and rare wildlife reserves, has attracted increasing concern. Compared with previous research mostly draws attention to the single exposure of MPs to the environment, greater emphasis should be placed on understanding the complex environmental behaviors of MPs. Therefore, the potential risks of MPs to ecosystems need to be explored in combination with their coexistence with other contaminants, but this is not well-understood. The presented study, taking Zhalong National Nature Reserve (Zhalong wetland), the largest habitat and breeding site for migratory Red-crowned cranes (Grus japonensis) in China, as an example, reveals the possibility of the co-exposure of MPs with various heavy metals. The average abundance of MPs in surface water and sediments in Zhalong Wetland is 738 particles/L and 7332 particles/kg, respectively, which is at a high level of MP pollution worldwide. The obtained results figure out that MPs are also widely found in Red-crowned cranes' feces and feathers. Notably, this study confirms that MP co-exposes to the wetland with Cr, Cd, and As via common sources, exposure routes, and the vector effect of MP. Importantly, we develop the methods of the environmental pressure for individual contaminants and achieve a comprehensive risk assessment of MPs co-exposure with other contaminants in the wetland ecosystem for the first time. It is found that co-exposure to heavy metal can increase the ecological risks of MPs. This is conducive to making a more standardized and reliable framework to estimate the environmental impacts of MP pollution and to formulate prevention and control policies.

Response of sedimentary microbial community and antibiotic resistance genes to aged Micro(Nano)plastics exposure under high hydrostatic pressure

Several studies reported that the presence of microplastics (MPs)/nanoplastics (NPs) in marine environments can alter microbial community and function. Yet, the impact of aged MPs/NPs on deep sea sedimentary ecosystems under high hydrostatic pressure remains insufficiently explored. Herein, the sedimentary microbial community composition, co-occurrence network, assembly, and transfer of antibiotic resistance genes (ARGs) in response to aged MPs/NPs were investigated. Compared with the control, NPs addition significantly reduced bacterial alpha diversity (p < 0.05), whereas MPs showed no significant impact (p > 0.05). Moreover, networks under NPs exhibited decreased complexity than that under MPs and the control, including edges, average degree, and the number of keystone. The assembly of the microbial community was primarily governed by stochastic processes, and aged MPs/NPs increased the importance of stochastic processes. Moreover, exposure to MPs/NPs for one month decreased the abundance of antibiotic resistance genes (ARGs) (from 94.8 to 36.2 TPM), while exposure for four months increased the abundance (from 40.6 to 88.1 TPM), and the shift of ARGs in sediment was driven by both functional modules and microbial community. This study is crucial for understanding the stress imposed by aged MPs/NPs on sedimentary ecosystems under high hydrostatic pressure.

Record of microplastic deposition revealed by ornithogenic soil and sediment profiles from Ross Island, Antarctica

Microplastics (MPs) are a global concern as an emerging pollutant, and the investigation on MPs in Antarctic aids in informing their global pollution assessments. Therefore, there are urgent scientific concerns regarding the environmental behavior, origins, influencing factors, and potential hazards of MPs in Antarctica. This study presents the characteristics of MPs from one ornithogenic sediment profile (coded CC) and two ornithogenic soil profiles (coded MR1 and MR2) from ice-free areas on Ross Island, Antarctica. We explored the potential sources of MPs and the main influencing factors for deposition based on their distribution with depth in the profiles. Through laser-infrared imaging spectroscopy (LDIR), a total of 30 polymer types were identified in all samples, with polyethylene terephthalate (PET) and polyvinyl chloride (PVC) as the dominant types, accounting for more than 70% of the total. The abundance of MPs in the CC sediment profile ranged from 2.83 to 394.18 items/g, while in MR1 and MR2 soil profiles, the abundance ranged from 2.25 to 1690.11 and 8.24 to 168.27 items/g, respectively. The size of MPs was mainly concentrated in the range of 20-50 μm, and possible downward movement of certain polymer types was revealed. From the perspective of temporal variation, we suggest that MPs were heavily influenced by local human activities including scientific research, fishing, and tourism, balanced by protective regulations, while no solid evidence was obtained to support strong influence from biological transport through penguins. This research enhances our understanding on the environmental behavior of MPs in the terrestrial systems of remote polar regions.

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.

Microplastic and antibiotics in waters: Interactions and environmental risks

Antibiotics (ATs) are ubiquitously detected in natural waters worldwide, and their tendency to co-migrate with microplastics (MPs) post-adsorption leads to heightened environmental risk. Research on the adsorption of ATs on MPs and their subsequent effects on the environmental risks is gaining significant attention globally. This adsorption process predominantly occurs through hydrophobic forces, hydrogen bonds, and electrostatic interactions and is influenced by various environmental factors. The interaction between MPs and ATs exhibited varying degrees of efficiency across different pH levels and ionic strengths. Furthermore, this paper outlines the environmental risks associated with the co-presence of MPs and ATs in aquatic environments, emphasizing the potential effect of MPs on the distribution of antibiotic resistance genes (ARGs) and related environmental risks. The potential hazards posed by MPs and ATs in aquatic systems warrant serious consideration. Future research should concentrate on the adsorption of ATs/ARGs on MPs under real environmental conditions, horizontal gene transfer on MPs, as well as biofilm formation and agglomeration behavior on MPs that needs to be emphasized.

Do microplastics accumulate in penguin internal organs? Evidence from Svenner island, Antarctica

The prevalence of microplastics (MPs, <5 mm) in natural environments presents a formidable global environmental threat MPs can be found from the Arctic to Antarctica, including glaciers. Despite their widespread distribution, studies on MP accumulation in apex predators inhabiting Polar Regions remain limited. The objective of this study was to conduct a comprehensive examination, for the first time, of MP bioaccumulation in various organs and tissue of Adélie penguins. This investigation comprehends the gastrointestinal tract (GIT), scat, internal organ (lung, trachea, spleen, and liver) and tissue (muscle) samples collected from Svenner Island, Antarctica during the 39th Indian expedition to Antarctica in 2019-2020. Our analyses revealed the presence of 34 MPs across the GIT, scat, lung, and trachea samples, with no MPs detected in muscle, spleen, or liver tissues. Blue-colored microfibers (>50 %) and MPs smaller than 1 mm (38 %) in size were prominently observed. Polymer characterization utilizing μ-FTIR spectroscopy identified low-density polyethylene (LDPE) (~63 %) as the predominant polymer type. The accumulation of MP fibers in the gastrointestinal tract and scat of Adélie penguins may originate from marine ambient media and prey organisms. Furthermore, the presence of LDPE fibers in the trachea and lungs likely occurred through inhalation and subsequent deposition of MPs originating from both local and long-range airborne sources. The identification of fibers ranging between 20 and 100 μm within the trachea suggests a plausible chance of cellular deposition of MPs. Overall our findings provide valuable insights into the organ-specific accumulation of MPs in apex predators. Adélie penguins emerge as promising environmental bio-monitoring species, offering insights into the potential trophic transfer of MPs within frigid environments.

Microplastics in bulk atmospheric deposition along the coastal region of Victoria Land, Antarctica

The increasing global concern over microplastic pollution has driven a surge in research efforts aimed at detecting microplastics across various ecosystems. Airborne microplastics (MPs) have been identified in remote environments worldwide, including Antarctica. However, data on bulk atmospheric deposition remain scarce. From January to December 2020, atmospheric deposition was directly collected using passive samplers placed in eight sites across Victoria Land. Using Raman Microspectroscopy, MPs were identified in six out of the seven samples collected (one sample was lost due to the extreme weather conditions). The average daily MP deposition for Victoria Land was 1.7 ± 1.1 MPs m-2 d-1, with values ranging from 0.76 to 3.44 MPs m-2 d-1. The majority (53 %) of MPs found in the atmospheric deposition were in the size class of 5-10 μm, and the main shape of MPs was fragments (95 %). The predominant plastic type was polypropylene (31 %), followed by polyethylene (19 %) and polycarbonate (12 %). Polystyrene, polyester, styrene and polyethylene terephthalate each accounted for ~6 %. Microplastics identified in the coastal sites may have local origins, potentially associated with scientific activities at research stations. Conversely, a backward trajectories analysis suggested a potential contribution of atmospheric transport to microplastic deposition at Larsen Glacier and Tourmaline Plateau, the two most remote sites of the study area, where the highest MP concentrations were detected. Our findings present the first evidence of microplastics in the Antarctic atmospheric deposition directly collected via passive samplers, highlighting the need for continued monitoring and research to assess the environmental impact of MPs, particularly in sensitive and remote ecosystems like Antarctica.

Airborne microplastic pollution detected in the atmosphere of the South Shetland Islands in Antarctica

Plastic pollution has emerged as a growing environmental concern, affecting even the most remote regions of the planet as the Antarctic continent, endangering its ecosystem and contributing to climate change. In this context, a continuous atmospheric microplastics monitoring study was conducted at Carlini Argentine Antarctic Station located in the southwest of 25 de Mayo (King George) Island (South Shetlands). Passive samplers were installed at three locations throughout the station, chosen based on the intensity of human activity and proved to be effective in collecting atmospheric particles over a one-year study period. Micro-FTIR and micro-Raman spectroscopies were used to characterize the suspected microplastic particles. These techniques revealed a wide variety of plastic polymers compositions and industrial dyes associated with textile and plastic materials. Microfibers were found to be the predominant particle form, constituting approximately 80% of the particles detected at each sampling point. Semi-synthetic cotton, polyester, and polyamide were widely detected, along with other plastic compositions. Micro-Raman spectroscopy confirmed the presence of indigo blue, reactive blue 238, and copper phthalocyanine on both synthetic and semi-synthetic fibers, representing the first report of these types of anthropogenic pigments in the Antarctic atmosphere. The results suggest a significant role of short-range transport from local human activities; however, the potential influence of large-scale atmospheric patterns should also be evaluated. Our findings highlight the need to expand the monitoring network to additional scientific stations and remote regions with minimal human activity. Increasing the number of observational sites and conducting complementary studies on airborne dispersion will strengthen assessments of potential long-range pollution sources.

Microplastics in ecosystems: Critical review of occurrence, distribution, toxicity, fate, transport, and advances in experimental and computational studies in surface and subsurface water

Microplastics (MPs), particles under 5 mm, pervade water, soil, sediment, and air due to increased plastic production and improper disposal, posing global environmental and health risks. Examining their distribution, quantities, fate, and transport is crucial for effective management. Several studies have explored MPs' sources, distribution, transport, and biological impacts, primarily focusing on the marine environment. However, there is a need for a comprehensive review of all environmental systems together for enhanced pollution control. This review critically examines the occurrence, distribution, fate, and transport of MPs in the following environments: freshwater, marine, and terrestrial ecosystems. The concentration of MPs is highly variable in the environment, ranging from negligible to significant amounts (0.003-519.223 items/liter in water and 0-18,000 items/kg dry weight sediment, respectively). Predominantly, these MPs manifest as fibers and fragments, with primary polymer types including polypropylene, polystyrene, polyethylene, and polyethylene terephthalate. A complex interplay of natural and anthropogenic actions, including wastewater treatment plant discharges, precipitation, stormwater runoff, inadequate plastic waste management, and biosolid applications, influences MPs' presence and distribution. Our critical synthesis of existing literature underscores the significance of factors such as wind, water flow rates, settling velocities, wave characteristics, plastic morphology, density, and size in determining MPs' transport dynamics in surface and subsurface waters. Furthermore, this review identifies research gaps, both in experimental and simulation, and outlines pivotal avenues for future exploration in the realm of MPs.

Advancing the Understanding of Microplastic Weathering: Insights from a Novel Polarized Light Scattering Approach

Weathering is a significant process that alters the properties of microplastics (MPs) and consequently affects their environmental behaviors. In this study, we introduced a novel approach based on polarized light scattering technique, which offers advantages in terms of rapid, high-throughput, and submicron-sized detection. This technique was successfully applied to characterize the weathered MPs after a 180-day laboratory simulation of coastal environments. By employing polarization measurements, we obtained a 46-dimensional matrix data set for the weathered MP fragments and subsequently processed them using a backpropagation neural network. The successful extraction of effective polarization pulses confirmed the presence of MP fragments within the size range of 0.2-60 μm, yielding total accuracies for size classification ranging from 78.9 to 86.9%. Furthermore, this technique achieved an overall accuracy of 93.8% in classifying MPs with different weathering degrees and polymer types, revealing polarization parameters associated with size and morphological changes play a dominant role in characterizing the weathering process of MPs. Compared with conventional approaches, the novel polarized light scattering approach holds great promise for rapid, high-throughput, and accurate characterization of MPs with small sizes. The findings of this study provided new insights into how MPs change after long-term weathering in aquatic environments.

Microplastic ingestion in five demersal, bathydemersal and bathypelagic fish species from the eastern Weddell Sea, Antarctica

Antarctica has traditionally been viewed as a relatively isolated ecosystem. Although still considered pristine, it is increasingly also being affected by microplastic pollution. Reported high sea floor concentrations raise concern that these ecosystems might act as major sink for microplastic pollution. This is significant as species in those remote ecosystems are likely more sensitive to rapid environmental change due to a high level of specialization, and lower tolerance levels. Microplastic ingestion in fish has barely been assessed in high latitude environments. Here we aimed to provide baseline data for the eastern Weddell Sea, which is particularly remote, and suggested for an area of conservation. By analyzing gastrointestinal tracts of 40 specimens from five species, we report an overall microplastic incidence rate of 0.23. This is lower than recent studies have found for other species in the Southern Ocean, and below global means. The highest incidence rate was detected in L. squamifrons (0.67), followed by P. evansii (0.29). The most common polymer was polyethylene recovered as 8 particles (42.1 %) from one specimen, while from the remaining 11 microplastics polyester was most common (36.8 %). This study shows that even in a remote region of the Antarctic Ocean with almost no vessel traffic, fisheries or touristic activity, bathydemersal and bathypelagic fish exhibit microplastic particles in their gastrointestinal tract.

Impact of COVID-19 pandemic on microplastic occurrence in aquatic environments: A three-year study in Taihu Lake Basin, China

The impact of the Coronavirus Disease 2019 (COVID-19) pandemic on microplastic (MP) occurrence in aquatic environments deserves an in-depth study. In this study, the occurrence of MPs and environmental flux of plastics before (2019) and during (2020 and 2021) the pandemic were comparatively investigated in various aquatic compartments in the Taihu Lake Basin in China. The field-based investigations from 2019 to 2021 for Taihu Lake have shown that, at the onset of the outbreak, the MP abundance declined at a rate of 62.3 %, but gradually recovered to the pre-pandemic level. However, the amount of plastics being released into aquatic environments showed a declining trend in 2020 and 2021 compared to those in 2019, with decrease rates of 13.7 % and 15.8 %, respectively. Characterization analysis of MP particles and source apportionment framework implied that while the contributions of tire abrasion and domestic waste to MP occurrence were depleted owing to the reduction in human activity during the pandemic, weathering and fragmentation of retained plastics contributed to the recovery of stored MPs. This study provides insights into the anthropogenic influences on MP occurrence, and supports policymakers in managing and controlling plastic contamination in large freshwater systems in the "new normal" phase.

Significant influence of land use types and anthropogenic activities on the distribution of microplastics in soil: A case from a typical mining-agricultural city

Microplastics pollution in soil has become a prominent issue in the field of ecological environment. However, relevant data on the microplastics pollution characteristics in mining industry-agricultural soil ecosystems is still limited. In this study, an extensive investigation on the characteristics of microplastics pollution in typical mining-agricultural city soil was conducted, revealing abundances, features, and influencing factors of microplastics in five land use types including facility farmland (FF), traditional farmland (TF), residential land (RL), industrial land (IL), and grassland (GL). The results showed that the distribution of microplastics abundances exhibits a nonuniform pattern, and the highest microplastics abundance was found in FF (3738 ± 2097 items·kg-1) compared with the other four land use types of this study area. Moreover, the key polymers identified were polypropylene (PP) and polyethylene (PE) with a smaller size (<0.01 mm) accounting for the majority at ,45 %, primary colors of microplastics were transparent with the dominant shapes being fibers and fragments. Additionally, principal component analysis and cluster analysis characterized microplastics features across various land use patterns, revealing that agricultural plastic waste, irrigation, and fertilization may be the main the primary sources of agricultural microplastics, while domestic sewage, household waste (include construction waste), and mining transportation activities are the potential urban sources. Correlation analysis indicates a positive relationship between TN, TP, SOC, and the abundances of microplastics (P < 0.05), and a negative relationship between pH and microplastic abundances. Furthermore, Cd, Cu, and As exhibit a significant positive correlation with microplastic characteristics (P < 0.05). Notably, the distribution trends of Cd content and microplastic abundance are similar. Overall, comprehensive analysis of environmental dynamics on microplastics in agricultural soil in coal industrial cities is crucial for developing effective measures to prevent and control microplastic pollution.

Diving into the Depths: Uncovering Microplastics in Norwegian Coastal Sediment Cores

High concentrations of microplastics (MPs) have been documented in the deep-sea surface sediments of the Arctic Ocean. However, studies investigating their high-resolution vertical distribution in sediments from the European waters to the Arctic remain limited. This study examines MPs in five sediment cores from the Norwegian Coastal Current (NCC), encompassing the water-sediment interface and sediment layers up to 19 cm depth. Advanced analytical methods for MP identification down to 11 μm in size were combined with radiometric dating and lithology observations. MPs were present across all sediment cores, including layers predating the introduction of plastics, with concentrations exhibiting significant variation (54-12,491 MP kg-1). The smallest size class (11 μm) predominated in most sediment layers (34-100%). A total of 18 different polymer types were identified across all sediment layers, with polymer diversity and depth correlations varying widely between stations. Our findings suggest that differences in seafloor topography and the impact of anthropogenic activities (e.g., fishing) lead to varying environmental conditions at the sampling sites, influencing the vertical distribution of MPs. This challenges the reliability of using environmental parameters to predict MP accumulation zones and questions the use of MPs in sediment cores as indicators of the Anthropocene.

Comprehensive Understanding on the Aging Process and Mechanism of Microplastics in the Sediment-Water Interface: Untangling the Role of Photoaging and Biodegradation

Microplastics (MPs) in coastal wetlands have been of great concern, but information on the aging behavior of MPs in the sediment-water interface is still lacking. In this study, the contribution of a typical abiotic (photoaging) and biotic (biodegradation) process and the underlying aging pathway of MPs with different degradabilities (including polypropylene, polyethylene terephthalate, and polylactic acid) were studied. With a quantified relative importance of photoaging (>55%) vs biodegradation, the crucial contribution of photoaging on MP aging was highlighted. This was likely attributed to more generation of reactive oxygen species (ROS) under sunlight irradiation conditions, containing O2•- and H2O2. By raising higher the level of malondialdehyde (0.5-3.5 times as high as that in the dark condition), these photochemically formed ROS caused oxidative stress and inhibited the selective attachment of plastic-degrading microbes on the MP surface, thereby weakening the effect of biodegradation. On this basis, the aging characteristics and potential pathway of different MPs were revealed. The functional group of nondegradable polypropylene tends to be broken by ROS first, while biodegradation (Arthrobacter oryzae and Bacillus sp.) played a relatively dominant role in biodegradable polylactic acid. This study provides a new sight for the understanding on the aging behaviors of MPs in the sediment-water interface.

Meta-analysis reveals the combined effects of microplastics and heavy metal on plants

The combined pollution of microplastics and heavy metals is becoming increasingly serious, and its effects on toxicology and heavy metal accumulation of plants are closely related to crop yield and population health. Here, we collected 57 studies to investigate the effect of microplastics on heavy metal accumulation in plants and their combined toxicity. An assessment was conducted to discover the primary pollutant responsible for the toxicity of combined pollution on plants. The study examined the influence of microplastic characteristics, heavy metal characteristics, and experimental methods on this pollutant. The results showed that combined toxicity of plants was more similar to heavy metals, whereas microplastics interacted with heavy metals mainly by inducing oxidative stress damage. Culture environment, heavy metal type, experimental duration, microplastic concentration and microplastic size were the main factors affecting heavy metal accumulation in plants. There was a negative correlation between experimental duration, microplastic concentration and microplastic size with heavy metal accumulation in plants. The interactions among influencing factors were found, and microplastic biodegradation was the core factor of the strong interaction. These results provided comprehensive insights and guiding strategies for environmental and public health risks caused by the combined pollution of microplastics and heavy metals.

Distribution characteristics and ecological risk analysis of microplastics in sediments and effluents related to offshore oil and gas activities in the Bohai Sea, China

Oil and gas activities are sources of marine microplastics (MPs) but have received less attention globally. This study assessed the distribution characteristics and ecological risks of MPs in 31 sediment samples and effluent samples of 5 oil and gas platforms related to offshore oil and gas activities in the Bohai Sea. The results showed that the mean abundance of MPs in sediment, produced water, and domestic sewage was 205.7 ± 151.5 items/kg d.w., 18 ± 11 items/L, and 26 ± 39 items/L, respectively. The MPs in sediments and effluents were dominated by transparent, rayon, and fibers <1 mm. Oil and gas activities may influence the abundance of MPs in the sediments. The sediments in the area were at a low level of risk, but some samples exhibited indexes beyond low levels. The mass of MPs carried by the effluents from oil and gas platforms in the Bohai Sea was less than that of other sources.

Low prevalence of microplastic contamination in the bottom sediments and deep-sea waters of the Bransfield strait, Antarctica

Despite the remoteness of the Antarctic continent and Southern Ocean, microplastic (MPs) contamination has been evidenced in recent years. However, the deep-sea compartments of the Southern Ocean are yet to be investigated. In the present study, we conducted a baseline MP assessment of the deep-sea waters and bottom sediments of the Bransfield Strait, Antarctica. A low abundance of suspected MPs was found. The average MP abundances in bottom sediments and water samples were 0.09 MP/g (range of 0-0.2 MP/g) and 7.00 MP/L (range of 0-16 MP/L), respectively. The majority of the particles were fibers identified as cellulose, although polyethylene terephthalate (PET) and polyacrylonitrile (PAN) was also detected. These results suggest low MP contamination levels in the Southern Ocean's deepest environmental compartments. However, future studies must aim to investigate the smallest MP fractions and, if possible, nanoplastic (<1 μm) contamination in these remote compartments.

Customized digestion protocols for copepods, euphausiids, chaetognaths and fish larvae facilitate the isolation of ingested microplastics

Degradation of oceanic plastic waste leads to the formation of microplastics that are ingested by a wide range of animals. Yet, the amounts that are taken up, especially by small zooplankton, are largely unknown. This is mostly due to the complex methodology that is required for isolating ingested microplastics from organisms. We developed customised, effective and benign digestion protocols for four important zooplankton taxa (copepods, euphausiids, chaetognaths and fish larvae), and assessed their digestion efficacy and their potential to cause particle loss or to alter microplastics using six polymers (HDPE, LDPE, PS, PET, PVC, PMMA). All protocols are based on an incubation of the organic matrix with 10% KOH at 38 °C, which is optionally combined with digestive enzymes (chitinase, proteinase K). This yielded digestion efficacies of > 98.2%, recovery rates of > 91.8%, < 2.4% change in microplastics' size, while no visual alteration of the microplastics and no changes in their spectra were observed when analysing them with a hyperspectral imaging camera. The proposed protocols are inexpensive (< 2.15 € per sample), but require several days when enzymatic digestion is included. They will facilitate research on microplastic ingestion by small marine organisms and thus enable well-founded conclusions about the threat that microplastics pose to these animals as well as about the role of biota in determining the vertical distribution of microplastics in oceanic environments.

Remote Mountainous Area Inevitably Becomes Temporal Sink for Microplastics Driven by Atmospheric Transport

Atmospheric transport drives the widespread distribution of microplastic (MP) in various ecosystems, posing a growing potential threat to environmental safety and human health. Understanding the source and fate of atmospheric MPs is thus crucial to constrain MP's widespread exposure. However, the source-sink dynamics of atmospheric MPs, especially in remote areas, are uncertain, and their transport routes have yet to be identified. Here, we conducted a 13-month monitoring of the atmospheric MPs in the uninhabited area of Mount Taibai, estimated the potential risk of MP exposure to the environment, and modeled the MP trajectory to analyze their transportation. We first found that as many as 15 polymer types of MPs, whose shapes mainly include fiber, fragments, films, and granules, maintained abundance (0.7 and 0.3 particle/m3 for PM10 and PM2.5, respectively) in the mountain atmosphere at respirable sizes. It is worth noting that the risk assessment results that comprehensively consider the influences of abundance and morphological characteristics suggest that the exposure level of MPs exhibits a risk even in this remote mountainous area that is not disturbed by frequent human activities. Backward trajectories revealed the likely source of MPs in the sparsely populated Liupan Mountains and Qinling Mountains of short-range transport. Further, polymer characteristics of MPs and airflow-based source analysis indicated the emission source of MPs in southern Xianyang in a longer-range transport. MPs were directionally transported to Mount Taibai through atmospheric transport under the premise of stable climate and geographical conditions. These suggest that MPs inevitably occur in remote mountainous areas driven by atmospheric transport, and the mountainous areas are persistently bearing the environmental impact of MP exposure. This study reveals the risk impacts of MP exposure and the transport dynamics of atmospheric MPs in a mountain ecosystem.

Characterization of the transcriptional effects of the plastic additive dibutyl phthalate alone and in combination with microplastic on the green-lipped mussel Perna canaliculus

The presence and persistence of microplastics (MPs) in diverse aquatic environments are of global concern. Microplastics can impact marine organisms via direct physical interaction and the release of potentially harmful chemical additives incorporated into the plastic. These chemicals are physically bound to the plastic matrix and can leach out. The hazards associated with chemical additives to exposed organisms is not well characterized. We investigated the hazards of plastic additives leaching from plastic. We used the common plasticizer dibutyl phthalate (DBP) as a chemical additive proxy and the New Zealand green-lipped mussel (Perna canaliculus) as a model. We used early-adult P. canaliculus exposed to combinations of virgin and DBP-spiked polyvinyl chloride (PVC), MPs, and DBP alone for 7 days. Whole transcriptome sequencing (RNA-seq) was conducted to assess whether leaching of DBP from MPs poses a hazard. The differences between groups were evaluated using pairwise permutational multivariate analysis of variance (PERMANOVA), and all treatments were significantly different from controls. In addition, a significant difference was seen between DBP and PVC MP treatment. Transcriptome analysis revealed that mussels exposed to DBP alone had the most differentially expressed genes (914), followed by PVC MP + DBP (448), and PVC MP (250). Gene ontology functional analysis revealed that the most enriched pathway types were in cellular metabolism, immune response, and endocrine disruption. Microplastic treatments enriched numerous pathways related to cellular metabolism and immune response. The combined exposure of PVC MP + DBP appears to cause combined effects, suggesting that DBP is bioavailable to the exposed mussels in the PVC MP + DBP treatment. Our results support the hypothesis that chemical additives are potentially an important driver of MP toxicity. Environ Toxicol Chem 2024;43:1604-1614. © 2024 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Do Antarctic bivalves present microdebris? The case of Livingston Island

Marine microdebris (MD) seem to be widespread in benthic invertebrates, even in the most remote areas of the planet such as Antarctica, although the information available is still very scarce. Here we provide a detailed quantification and characterization of the MD found on three common bivalve species (Aequiyoldia eightsii, Thracia cf. meridionalis, and Cyclocardia astartoides) inhabiting shallow areas in Johnsons' Bay, Livingston Island (South Shetland Islands, Antarctica) as a snapshot of the MD present. On average, these bivalves contained 0.71 ± 0.89 items per individual and 1.49 ± 2.35 items per gram, being comparable to the few previous existing studies in other Antarctic areas. Nearly half of the organisms analysed here (45.6 %), contained at least one item. No significant differences were found in the three bivalve species. As far as we know, this is the first study to analyse and compare MD in three bivalve species in the Antarctic Peninsula. Although our results indicate bivalves are as not as polluted as in other areas of the planet, this is remarkable since this is considered one of the last pristine areas of the world. Our results point to local activities as the main source of MD pollution in Livingston Island, although global pollution cannot be discarded. We believe this research provides a useful baseline for future studies and will contribute to develop policies and strategies to preserve Antarctic marine ecosystems from MD pollution.

Unveiling high concentrations of small microplastics (11-500 μm) in surface water samples from the southern Weddell Sea off Antarctica

Recent studies have highlighted the prevalence of microplastic (MP) pollution in the global marine environment and these pollutants have been found to contaminate even remote regions, including the Southern Ocean south of the polar front. Previous studies in this region have mostly focused on MPs larger than 300 μm, potentially underestimating the extent of MP pollution. This study is the first to investigate MPs in marine surface waters south of the polar front, with a focus on small MPs 500-11 μm in size. Seventeen surface water samples were collected in the southern Weddell Sea using an in-house-designed sampling system. The analysis of the entire sample using micro-Fourier transform infrared spectroscopy (μFTIR) with focal plane array (FPA) detection revealed the presence of MPs in all samples, with the vast majority of the MPs detected being smaller than 300 μm (98.3 %). The mean concentration reached 43.5 (± 83.8) MPs m-3, with a wide range from 0.5 to 267.2 MPs m-3. The samples with the highest concentrations differed from the other samples in that they were collected north of the continental slope and the Antarctic Slope Current. Sea ice conditions possibly also influenced these varying concentrations. This study reports high concentrations of MPs compared to other studies in the region. It emphasizes the need to analyze small MPs, down to a size of 11 μm or even smaller, in the Antarctic Treaty Area to gain a more comprehensive understanding of MP pollution and its potential ecological impacts.

Simulation of the dynamic processes of microplastic suspension and deposition in a lake sediment-water system

The occurrence of microplastics in aquatic environments has attracted increasing interest from both the public and scientists, especially their migration behaviors. Although several environmental behaviors of microplastics have been studied, the issue of microplastic suspension and deposition in lake sediment-water systems remains to be elucidated. In this study, we built an indoor sediment-water system with input and output rivers that simulated the actual situations in lakes, and aimed to explore the suspension and deposition behavior of microplastics using eight group experiments. The abundance of microplastics in overlying water and sediments in different periods was analyzed, and the characteristics of hydrodynamic disturbance on microplastic suspension and deposition were identified. Importantly, the exchange of microplastics in sediments and water under dynamic flow conditions was assessed. The results showed that the middle-scale experiment designed in this study effectively simulated the dynamic transport process of microplastics in lakes, and the hydrodynamic force had a significant impact on the suspension and deposition behaviors of microplastics. The average abundance of polystyrene, polyethylene terephthalate and polyamide microplastics was 1.07, 0.60 and 0.83 particles/L in overlying water during the suspension experiments, respectively. This showed a pattern of first rising and then falling with the extension of suspension time. Even in the environment with the maximum input water volume (8000 ml/min) in this study, only microplastics at a depth of 0 to 2 cm from the sediment were suspended. The average abundance of microplastics was 313.02 particles/kg during the deposition experiments, which gradually increased with the extension of deposition time in sediments. Finally, microplastic sizes in water of the suspension experiments and in sediments of the deposition experiments were concentrated in the range of 500 to 1500 μm and 300 to 1000 μm, respectively.

Understanding microplastic pollution of marine ecosystem: a review

Microplastics are emerging as prominent pollutants across the globe. Oceans are becoming major sinks for these pollutants, and their presence is widespread in coastal regions, oceanic surface waters, water column, and sediments. Studies have revealed that microplastics cause serious threats to the marine ecosystem as well as human beings. In the past few years, many research efforts have focused on studying different aspects relating to microplastic pollution of the oceans. This review summarizes sources, migration routes, and ill effects of marine microplastic pollution along with various conventional as well as advanced methods for microplastics analysis and control. However, various knowledge gaps in detection and analysis require attention in order to understand the sources and transport of microplastics, which is critical to deploying mitigation strategies at appropriate locations. Advanced removal methods and an integrated approach are necessary, including government policies and stringent regulations to control the release of plastics.