The missing ocean plastic sink: Gone with the rivers

The Three Gorges Dam alters the spatial distribution and flux of microplastics in the Yangtze River

The construction of dams disrupts the natural connectivity of rivers, potentially altering the distribution and movement of pollutants. However, the impacts of dams on microplastic (MP) flux are scarcely considered. By integrating previous findings and conducting supplementary sampling, we mapped the distribution of MPs in the Three Gorges Reservoir (TGR), covering surface water, sediment, the hydro-fluctuation belt, and the riparian zone. The TGR serves as a significant accumulation zone for MPs, with a notably higher concentration of MPs in its water compared to the upstream river water. In the reservoir, MPs are concentrated in the upstream and downstream sections of the water column, the hydro-fluctuation belt and sediment, whereas in the riparian zone, concentrations are higher in the downstream section. The distribution of MPs in reservoir water is strongly correlated (R2 > 0.9) with regional gross domestic product (GDP) and sewage discharge, whereas the factors influencing MPs in sediment, the hydro-fluctuation belt, and the riparian zone are more complex. Human activities, particularly wastewater discharge in populated areas, predominantly contributed 49.89 % to the MPs load in the reservoir. The TGR captures approximately 11,091 ± 6,998 tons of MPs annually, constituting 28.18 % of the MPs flux from the upper Yangtze River.

Fate of polystyrene micro- and nanoplastics in zebrafish liver cells: Influence of protein corona on transport, oxidative stress, and glycolipid metabolism

Micro- and nanoplastics (MNPs) form protein corona (PC) upon contact with biological fluids, but their impact on the intracellular transport, distribution, and toxicity of MNPs remains unclear. Fetal bovine serum (FBS) and bovine serum albumin (BSA) were used to simulate in vivo environment, this study explored their influence on the transport and toxicity of polystyrene (PS) MNPs in zebrafish liver (ZFL) cells. Results showed PS MNPs were wrapped by proteins into stable complexes. Nanoparticles (NP, 50 nm) and their protein complexes (NP@PC) were internalized by cells within 6 h, with PC formation enhancing NP uptake. NP primarily entered cells through clathrin- and caveolae-mediated endocytosis, while NP@PC via clathrin-mediated pathways. Internalized particles were predominantly in lysosomes where PC degraded and some were also in mitochondria. Eventually, particles were expelled from cells through energy-dependent lysosomal pathways and energy-independent membrane penetration mechanisms. Notably, PC formation limited the clearance of NP. In toxicity, NP had a more severe impact than microplastics (MP, 5 μm). FBS more effectively mitigated PS MNPs-induced reactive oxygen species accumulation, subcellular structural damage, and dysregulation of glycolipid metabolism than BSA did. This study elucidates the modulatory role of PC on biological effects of MNPs, providing safety and risk management strategies.

Insights into suspended sediment and microplastic budget of a lowland river: integrating in-situ measurements, Sentinel-2 imagery, and machine learning

The calculations on fluvial microplastic load (MPL) provide dynamic and actionable metrics for understanding microplastic (MP) particle emissions to the downstream environment. However, most of the concentration data reported in the literature do not reflect the total amount of transported MPs. This study aims to quantify the MPLs in the Middle and Lower Tisza River, Hungary by combining multiscale, frequent in-situ measurements of MP concentration (MPC) and suspended sediment concentration (SSC) in the river with Sentinel-2 and ANN-based models. MPC data were integrated with daily water discharge, applying correction factors to account for vertical variability in the water column. The results indicate the crucial role of hydrology in suspended sediment (SS) and MP transport. During floods SS load (SSL) (6706 ± 7449 ton/day) and MPL (1.71 × 109 ± 1.40 × 109 item/day) were 6.5 and 5.1 times higher than at low stage (SSL: 1031 ± 755 ton/day; MPL: 0.339 × 109 ± 0.399 × 109 item/day), respectively. Vertical measurements indicated a generally increasing SSC trend toward the riverbed, amplifying the SSL correction factor, while decreasing MPC led to attenuation for MPL correction factors. Satellite-derived estimates at four sites in the Middle and Lower Tisza revealed an increasing downstream trend in SSL and MPL, although natural and anthropogenic factors slightly influence this trend. Rating curves were established at the four sites with an R2 range of 0.55 (Mindszent) to 0.82 (Zenta) for SSL and 0.53 (Mindszent) for MPL. Although the accuracy of the rating curves is moderate to very strong, they still offer practical predictions based solely on water discharge data.

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.

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

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

Guidelines toward ecologically-informed bioprospecting for microbial plastic degradation

Biological degradation of plastics by microbial enzymes offers a sustainable alternative to traditional waste management methods that often pollute the environment. This review explores ecologically-informed bioprospecting for microorganisms possessing enzymes suitable for biological plastic waste treatment. Natural habitats enriched in plastic-like polymers, such as insect-derived polyesters, epicuticular microbial biofilms in the phyllosphere of plants in extreme environments, or aquatic ecosystems, are highlighted as promising reservoirs for bioprospecting. Anthropogenic habitats, including plastic-polluted soils and the plastisphere, have yielded potent enzymes such as PETases and cutinases, which are being exploited in biotechnology. However, bioprospecting in plastispheres and artificial environments frequently leads to the isolation of environmental opportunistic microorganisms, such as Pseudomonas aeruginosa, Aspergillus fumigatus, Parengyodontium album, or species of Fusarium, which are capable of becoming human and/or plant pathogens. These cases necessitate stringent biosecurity measures, including accurate molecular identification, ecological assessment, and containment protocols. Beyond advancing bioprospecting approaches toward a broader scope of relevant habitats, this review underscores the educational value of such screenings, specifically, in understudied natural habitats, emphasizing its potential to uncover novel enzymes and microorganisms and engage the next generation of researchers in interdisciplinary study integrating environmental microbiology, molecular biology, enzymology, polymer chemistry, and bioinformatics. Finally, we offer guidelines for microbial bioprospecting in various laboratory settings, ranging from standard environmental microbiology facilities to high-biosecurity facilities, thereby maximizing the diversity of scientists who may contribute to addressing urgent environmental challenges associated with plastic waste.

Harmonious assessment of mesh effect in water sieve sampling for fibrous microplastics abundance

Fibrous microplastic pollution in natural water is increasingly concerning because these particles could carry and release toxic substances, and be bioavailable of microplastics less than 100 μm, posing significant risks to ecosystems and human health. Effective monitoring and accurate data sharing are hampered by a lack of standardized sampling methods, particularly for assessing the impact of mesh size (hereafter referred to as mesh opening) on microplastics abundance. This study investigated the efficiencies of various mesh openings (50-500 μm) in water sieve sampling of fibrous microplastics using a continuous multi-layer filtration device. Surface water samples from Zhanqiao Pier, China, were processed, and the geometric properties of the collected microplastics were analyzed. The retention of fibrous microplastics was calculated using logistic models, and Monte Carlo simulations were employed to estimate the amounts of microplastics that were not retained. Data from previous studies were re-evaluated to develop a harmonious assessment protocol for estimating fibrous microplastics abundance. The results showed that larger mesh openings significantly underestimate the abundance of microplastics, missing up to 14.6 (500 μm), 8.8 (315 μm), and 2.0 (150 μm) times more fibers compared to the finest mesh opening (50 μm). Thus, coarser meshes fail to capture smaller, yet numerous, microplastics fibers. Moreover, the re-evaluated results were used to develop correction factors of the harmonious assessment and highlight the need for finer mesh openings in sampling nets and sieves to ensure more accurate data collection. Such improvements could be used to establish a globally standardized methodology for microplastics monitoring.

Concentrations of organic pollutants in seabirds from the tropical southwestern Atlantic Ocean are explained by differences in foraging ecology

Persistent organic pollutants are a potential threat for marine vertebrates in both coastal and offshore areas. In this study, organic pollutants were evaluated in the blood and feathers of four seabird species that forage in the tropical southwestern Atlantic Ocean. Red-billed tropicbirds (Phaethon aethereus) and brown boobies (Sula leucogaster) were sampled in the Abrolhos Archipelago, 70 km from the coast, and used as proxies of nearshore contamination. The Trindade petrel (Pterodroma arminjoniana) was sampled on Trindade Island, 1200 km offshore, and the Atlantic yellow-nosed albatross (Thalassarche chlororhynchos) was sampled at sea, both used as proxies of pelagic contamination. Concentrations of organohalogen pesticides (∑OHP) and polychlorinated biphenyls (∑PCB) were generally higher in the booby, the most nearshore forager, followed by the tropicbird, petrel and the albatross. Carbon isotope values (δ13C) were positively associated with ∑OHP and ∑PCB in the blood of seabirds and explained 28.6% of the variation in pollutant data, suggesting higher concentrations of pollutants in the nearshore marine habitats, where δ13C is generally higher. Nitrogen isotope values (δ15N) also had a positive influence over pollutant concentrations and explained 13% of pollutant data, suggesting an influence of trophic level. Variations in polycyclic aromatic hydrocarbon (∑PAH) concentrations among species, and relationships with isotopic values were less clear. Furthermore, the concentrations of organic pollutants were substantially higher in 2019 than 2022, which suggests greater environmental pollution in 2019 that could be related to urban and agricultural sources. Results demonstrate relationships between seabird ecology and organic pollutants in the tropical marine environment and highlight the importance of assessing multiple species in monitoring pollutant concentrations in wildlife.

Significant microplastic accumulation and burial in the intertidal sedimentary environments of the Yellow River Delta

Estuarine intertidal habitats provide a dynamic and distinctive environment for the transport of microplastics, yet their migration and accumulation in these areas remain poorly understood. Herein, the spatial distribution patterns of microplastics in the estuarine sedimentary environment of the Yellow River Delta were investigated across elevation and depth gradients. Compared to the subtidal and supratidal zones, the estuarine intertidal zone exhibited the highest microplastic abundance in sediment (1027 ± 29 items/kg). Sediment cores revealed that the highest microplastic abundance occurred at a depth of 5-10 cm. The evolution of microplastic size and morphology characteristics with sediment depth indicates vertical transport of microplastics in estuarine sediments. The strong correlations between organic matter, silt content, and microplastics abundance in estuarine sediments suggested significant impacts of tidal hydrodynamics and sediment characteristics on microplastic migration processes. Estimates indicated that microplastic burial in the deeper sediments (638.7 tons in the 5-30 cm layer) was 1.96 times greater than that in the upper layers. Distinct variations in the carbonyl index across habitats suggested that tidal-induced dynamic redox conditions in the intertidal zone promoted both biotic and abiotic aging processes of microplastics. This study provides new insights into the environmental behavior and long-term fate of microplastics in estuarine intertidal sedimentary environments.

Lanternfish as bioindicator of microplastics in the deep sea: A spatiotemporal analysis using museum specimens

We investigated MP ingestion in lanternfishes (Myctophidae), one of the most abundant vertebrates in the world, using archived specimens from museum collections from 1999 to 2017. Microplastics were detected in 55 % of the 1167 specimens analysed (0.95 ± 1.22 MP individual-1). Global plastic production has increased by about 53 % during this period. Interestingly, almost half of the lanternfishes analysed contained at least one particle in the gastrointestinal tract in the earliest data. In contrast, the incidence increased to two-thirds in the most recent data available. Although the shape and colour composition of MPs followed a similar proportion, the model considering the sampling year and migration patterns showed that specimens collected in 1999, 2000, and 2010 had a 44 %, 23 % and 20 % lower probability of MP ingestion than those collected in 2017. However, migration was the most robust predictor of MP contamination. Further analysis of specimens collected in 1999-2000 revealed that fish caught in the bathypelagic zone had the lowest number of particles, while those caught just below the thermocline had an eightfold higher probability of MP ingestion. Lanternfishes were generally more likely to ingest high-density polymers, although polyethylene had the highest concentration (445.5 ± 526.4 µg g-1 gastrointestinal tract).

Plastics in the city: spatial and temporal variation of urban litter in a coastal town of France

Plastics are ubiquitous in the environment, causing pollution recognized as a marker of the Anthropocene era. All environments are affected, including coastal and river ecosystems, where studies have shown that plastic waste contamination is proportional to the level of urbanization. This study, to our knowledge, is the first in France to investigate the spatial and temporal distribution of litter across the Land-Sea continuum, using debris classifications based on OSPAR (Oslo-Paris Convention 1992) and EPR (Extended Producer Responsibility). Two samplings, involving the local population and various non-governmental organizations, were conducted in 2022 and 2023 in the coastal town of Banyuls-sur-Mer, France, located near the Spanish border, with the Baillaury River running through it. The entire town, as well as the port and Central Beach, were sampled. A total of 30,899 debris (1357 kg) were collected over 47.7 km of streets, riverbanks, port, and beach. Most of the debris collected in the port consisted of tires. The amount of waste collected in the town was lower than that observed on the riverbanks or at Central Beach, suggesting that coastal areas serve as the final repository for mismanaged waste. Plastics represent approximately 70% of the collected debris and exceed the precautionary threshold for ecological and socio-economic nuisances defined for European Union (EU) beaches (i.e., 20 debris per 100 m), by the Technical Group on Marine Litter of the Framework Directive "Strategy for the Marine Environment" (FD SMM). The data collection and standardization methods used in this study facilitated direct comparison across the continuum land-sea between cities, riverbanks, ports, and beaches, and with other studies, highlighting the value of participatory science in informing decision-making.

Comparison of macrolitter and meso- and microplastic pollution on French riverbanks and coastal beaches using citizen science with schoolchildren

Rivers are the major source of anthropogenic litter entering the ocean, especially plastic debris that accumulates in all ecosystems around the world and poses a risk to the biota. Reliable data on distribution, abundance, and types of stranded plastics are needed, especially on riverbanks that have received less attention than coastal beaches. Here, we present the citizen science initiative Plastique à la loupe (Plastic under the magnifier), which compares for the first time the distribution of different litter sizes (macrolitter and meso- and microplastics) over 81 riverbanks and 66 coastal beaches sampled in France between 2019 and 2021. A total of 147 school classes (3113 schoolchildren) from middle to high school collected, sorted, and enumerated 55,986 pieces of plastic to provide a baseline of the current pollution by stranded debris at the national level. Single-use plastics (mainly food-related items) were very abundant on riverbanks (43%), whereas fragmented debris dominated the macrolitter on coastal beaches (28%). Microplastics were always higher in number compared to mesoplastics and macrolitter, with polystyrene and polyethylene found in equivalent proportions on riverbanks while polyethylene dominated microplastics on coastal beaches. Tracing the source of plastic items was possible only for a small proportion of the numerous collected items, mainly for identifiable macrolitter and microplastic pellets. This study lays out the foundations for further works using the Plastique à la loupe citizen science initiative in France and additional comparisons to other studied habitats worldwide, which can be used by scientists and policy-makers for future litter monitoring, prevention and clean-up strategies.

A Pan-European study of the bacterial plastisphere diversity along river-to-sea continuums

Microplastics provide a persistent substrate that can facilitate microbial transport across ecosystems. Since most marine plastic debris originates from land and reaches the ocean through rivers, the potential dispersal of freshwater bacteria into the sea represents a significant concern. To address this question, we explored the plastisphere on microplastic debris (MPs) and on pristine microplastics (pMPs) as well as the bacteria living in surrounding waters, along the river-sea continuum in nine major European rivers sampled during the 7 months of the Tara Microplastics mission. In both marine and riverine waters, we found a clear niche partitioning among MPs and pMPs plastispheres when compared to the bacteria living in the surrounding waters. Across this large dataset, we found that bacterial community structure varied along the river salinity gradient, with plastisphere communities exhibiting almost complete segregation between freshwater and marine ecosystems. We also described for the first time a virulent human pathogenic bacterium (Shewanella putrefaciens), capable of infecting human intestinal epithelial cells, detected exclusively on MPs in riverine environments. Our findings indicate that salinity is the main driver of plastisphere communities along the river-to-sea continuum, helping to mitigate the risk of pathogens transfer between freshwater and marine systems.

Mission Tara Microplastics: a holistic set of protocols and data resources for the field investigation of plastic pollution along the land-sea continuum in Europe

The Tara Microplastics mission was conducted for 7 months to investigate plastic pollution along nine major rivers in Europe-Thames, Elbe, Rhine, Seine, Loire, Garonne, Ebro, Rhone, and Tiber. An extensive suite of sampling protocols was applied at four to five sites on each river along a salinity gradient from the sea and the outer estuary to downstream and upstream of the first heavily populated city. Biophysicochemical parameters including salinity, temperature, irradiance, particulate matter, large and small microplastics (MPs) concentration and composition, prokaryote and microeukaryote richness, and diversity on MPs and in the surrounding waters were routinely measured onboard the French research vessel Tara or from a semi-rigid boat in shallow waters. In addition, macroplastic and microplastic concentrations and composition were determined on river banks and beaches. Finally, cages containing either pristine pieces of plastics in the form of films or granules, and others containing mussels were immersed at each sampling site, 1 month prior to sampling in order to study the metabolic activity of the plastisphere by meta-OMICS and to run toxicity tests and pollutants analyses. Here, we fully described the holistic set of protocols designed for the Mission Tara Microplastics and promoted standard procedures to achieve its ambitious goals: (1) compare traits of plastic pollution among European rivers, (2) provide a baseline of the state of plastic pollution in the Anthropocene, (3) predict their evolution in the frame of the current European initiatives, (4) shed light on the toxicological effects of plastic on aquatic life, (5) model the transport of microplastics from land towards the sea, and (6) investigate the potential impact of pathogen or invasive species rafting on drifting plastics from the land to the sea through riverine systems.

From source to sink: part 1-characterization and Lagrangian tracking of riverine microplastics in the Mediterranean Basin

The Mediterranean Sea is one of the most critically polluted areas due to its semi-enclosed structure and its highly anthropized shoreline. Rivers are significant vectors for pollutant transfers from the continental to the marine environment. In this context, a 3D Lagrangian simulation of the dispersion of riverine microplastics (MPs) was performed, which included the application of a recently developed model that reassessed the MP fluxes discharged by rivers. MP physical properties from river samples were further investigated to approximate vertical displacement in modeled ocean currents. The use of a high-resolution circulation model, integrating Stokes drift, turbulent diffusion, and MP sinking and rising velocities, enabled us to establish stock balances. Our simulation suggested that 65% of river inputs may be made of floating MPs drifting in the surface layer and 35% of dense MPs sinking to deeper layers. The Eastern Mediterranean tends to accumulate floating MPs, primarily originating from the Western Mediterranean Basin, where major river sources are concentrated. After 2 years of simulation, modeled stranding sequestered 90% of the MP inputs, indicating relatively short average residence times from a few days to months at most for particles at sea. Although spatial distribution patterns stabilized after this period and a steady state may have been approached, the surface concentrations we modeled generally remained below field observations. This suggested either an underestimation of sources (rivers and unaccounted sources), by a factor of 6 at most, or an overestimation of MP withdrawal through stranding, to be reduced from 90 to around 60% or less if unaccounted sinks were considered.

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.

Small microplastics have much higher mass concentrations than large microplastics at the surface of nine major European rivers

Understanding the fates and impacts of microplastics requires information on their sizes, polymer types, concentrations, and spatial and temporal distributions. Here, we focused on large (LMPs, 500 µm to 5 mm) and small (SMPs, 25 to 500 µm) microplastics sampled with the exact same protocol in nine of the major European rivers during the seven months of the Tara Microplastic Expedition. Attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) and pyrolysis coupled with gas chromatography and mass spectrometry (Py-GC-MS) analyses were used to determine the microplastics contents by number and mass. The median LMP concentration was 6.7 particles m-3, which was lower than those in other regions of the world (America and Asia). The SMP mass concentration was much higher to the LMP concentrations, with SMP/LMP ratios up to 1000 in some rivers. We did not observe a systematic positive effect of urban areas for the two size classes or polymers; this could be explained by the fact that the transport of microplastic is highly heterogeneous in rivers. We believe that this study has important implications for predictive models of plastics distribution and fate in aquatic environments.

Marine litter in the deepest site of the Mediterranean Sea

From the scientific viewpoint, the deepest ocean includes the least known regions on Earth. Advanced technologies, complex logistics and very specific expertise, requiring adequate funding, are needed for in situ observation of the deep sea. In this paper we present the results of the inspection of the floor of the deepest site in the Mediterranean Sea, the 5122 m in depth Calypso Deep in the Ionian Sea, with the Human Occupied Vehicle (HOV) Limiting Factor by Caladan Oceanic in 2020. The dive videos show the floor of the Calypso Deep littered by anthropogenic debris, with litter concentrations among the highest ever recorded in a deep sea environment. The dominant litter category by material type is plastics, accounting for 88 % of the identified litter items. No interactions have been found between litter and the rare life forms identified so far in the deep Ionian Sea. This illustrates that the deep sea is often a final sink for pollution and as such deserves more attention on associated processes and impacts. Harmonized monitoring and assessment should include the deep sea areas in order to enable efficient mitigation. Our findings provide a strong argument in favour of the urgent implementation at global scale of policy actions to reduce ocean littering thus easing the conservation of unique marine habitats, including the deepest on Earth. Our results also appeal to the society at large in terms of consumption habits, waste reduction, care of the environment and the pressing need for action to protect our ocean.

Distinctive lipidomic responses induced by polystyrene micro- and nano-plastics in zebrafish liver cells

Despite growing awareness of the size-dependent toxicity caused by micro- and nano-plastics (MNPs) in fish, the modulation of the liver lipidome as a function of particle size has not been thoroughly investigated. This study explores the subcellular and molecular responses induced by polystyrene microplastics (MPs, 1 µm) and nano-plastics (NPs, 52 nm) in zebrafish liver (ZFL) cells, with a focus on the modulation of the cell's lipidome and gene expression profiles. Both particle sizes are readily internalized by ZFL cells; however, NPs had a more pronounced impact compared to MPs. Lipidomic analysis revealed that MPs decreased polyunsaturated phospholipids, while NPs increased ether-linked phosphatidylcholines (PC-Ps/PCOs). Gene expression analysis showed that high concentrations of MPs down-regulated the expression of fatty acid synthesis related genes, and significantly downregulated the microsomal triglyceride transfer protein (mtp) gene, indicating a perturbation in lipid storage metabolism, which was not observed for NP exposure. In contrast, NPs induced a dose-dependent accumulation of lipids, suggesting increased lipid droplet formation and an activation of ceramide-mediated apoptosis pathway. These findings provide new insights into the molecular mechanisms of MNP toxicity and emphasize the importance of considering particle size when assessing environmental and health risks. Furthermore, this study highlights the potential of lipidomics for elucidating the mechanisms underlying MNP toxicity, prompting further research into of the long-term consequences of exposure.

From source to sink: part 2-seasonal dispersion of microplastics discharged in the NW Mediterranean Sea by the Rhone River in southern France

As the largest individual contributor of freshwater inflow to the basin, the Rhone River is likely to be one of the main sources of microplastics (MPs) to the Mediterranean Sea. In order to predict the fate of MPs discharged by the Rhone River, an innovative 3D Lagrangian dispersion of its particles associated with vertical velocities was modeled in Mediterranean ocean currents. Through winter and summer scenarios, the seasonal variability of transfers and the corresponding accumulation areas were depicted in the Northwestern Basin according to hydrodynamic conditions on the continental shelf of the Gulf of Lion and to the frontal dynamics from the Pyrenees to the North Balearic fronts. Our results indicated that MP transfers were driven by mesoscale and sub-mesoscale structures, resulting in steep concentration gradients across fronts during summer, while winter energetic mixing favored a more efficient and homogeneous spreading. After a year of drift, high MP retention (up to 50%) occurred in the coastal zone of the Gulf of Lion near the river mouth, with a large contribution of sinking MPs and an increase in stranding during the highest freshwater inflows of the winter season. Conversely, up to 60% of the floating MPs were exported to the Algerian Basin and then to the Eastern Mediterranean. This west-to-east transfer led to significant stranding on the islands, prevailing on the northern coasts of the Balearic Islands in winter (6% of floating inputs) and on the western coasts of Corsica and Sardinia in summer (13%). The southern Mediterranean coasts, from Algeria to Tunisia, represented also a major sink for floating debris with stranding ranging from 9 to 35% of MPs discharged in winter and in summer, respectively. We estimated that 3.5 to 5 t of the Rhone MPs remained in the surface layer at the end of the year, with high concentrations in the Ionian Sea.

Microplastic pollution in the water column and benthic sediment of the San Pedro Bay, California, USA

The concentration, character, and distribution of microplastics in coastal marine environments remain poorly understood, with most research focusing on the abundance of microplastics at the sea surface. To address this gap, we conducted one of the first comprehensive assessments of microplastic distribution through the marine water column and benthic sediment during the wet and dry season in the coastal waters of the San Pedro Bay Southern California, USA. Microplastic concentrations in the water column did not vary significantly across season but were significantly higher in nearshore environments and at the surface of the water column. Sediment samples contained significantly more microplastics in the wet season and in offshore environments. Black particles were the most dominant color, while fibers were the most abundant morphology, accounting for over 50% of both water column and sediment microplastics. Polyethylene and polypropylene were identified as the most abundant polymers in the water column regardless of morphology type. Tire and road wear particles were found through the study domain. Average microplastic concentrations in the San Pedro Bay were estimated to be 8.65 × 105 ± 7.60 × 105 particles/km2 and 3.19 ± 2.96 particles/m³. This study highlights the complexity of microplastic concentration, character, and distribution in marine environments and demonstrates that surface only sampling strategies significantly underestimate microplastic concentrations. Our findings underscore the need for continued and expanded research into microplastic distribution and transport dynamics across the marine environment to aid in understanding, managing, and mitigating plastic pollution in coastal marine systems.

Long-Term Changes in the Abundance, Size, and Morphotype of Marine Plastics in the North Pacific

Understanding the spatiotemporal dynamics of microplastics on the ocean surface is crucial for assessing their impact on marine ecosystems and human health; however, long-term fluctuations have not been extensively studied. We present a long-term empirical data set on floating marine plastic debris collected from 1949 to 2020 around Japan in the western North Pacific. We observed three phases: 1) a period of increase (0-104 pieces/km2) from the early 1950s to the late 1970s; 2) a stagnation period, with high abundance (104-105 pieces/km2), from the 1980s to the early 2010s; and 3) a period of reincrease (>105 pieces/km2) from the mid-2010s to the present. The shift from film to fragmented plastic in the 1980s and the continuous downsizing may have caused the expansion of the offshore polluted area, resulting in a stagnation period by enhancing removal. The removal is most likely caused by sedimentation with phytoplankton, as the abundance of the plastic debris during this period was significantly related to the winter Pacific Decadal Oscillation, an index of annual primary productivity. The recent increase in microplastics suggests that plastic discharge is outpacing its removal capacity, suggesting that the impact of pollution on ocean surface biota is becoming increasingly evident.

Patterns and trends in marine microplastics density distributions using a long-term, global, field database

We evaluate global microplastics particle density distribution using field data from 1972 to 2022, made available by the NOAA (National Oceanic and Atmospheric Administration) NCEI (National Centers for Environmental Information) global marine microplastics database. We resampled the measured microplastics density data from NOAA NCEI into a regularly spaced 1° × 1° grid and applied ordinary block kriging on a 1° × 1° mask map of the global oceans to spatially interpolate the gridded data. Climate data were retrieved from the Climate Data Store of the Copernicus Climate Change Service. Our evaluation suggests that global microplastics particle density roughly doubled every decade but that there are regional variations. Global average microplastics density correlates strongly with total global precipitation and seasonal changes appear strong in the North Pacific but not in the North Atlantic. We find that microplastics density in the North Pacific increases with El Niño Southern Oscillation and Pacific Decadal Oscillation respective indices ONI (Oceanic Niño Index) and PDO, and decreases with North Atlantic Oscillation index, NAO. In the western North Atlantic, there is no demonstrable relationship with any of these low-frequency oscillations. Our microplastics density distribution maps are expected be useful for verifying satellite remote sensing algorithms, assessing overlaps with sensitive and vulnerable populations, species, and ecosystems, and assessing climate change impacts.

Interactions of anthropogenic microfibres with the marine macroalga, Ulvalactuca

Little information exists on the interactions between microfibres (MFs) and marine macroalgae. In this study, the translucent green seaweed, Ulva lactuca, has been exposed to ∼2 mg L-1 suspensions of MFs prepared from dryer lint under controlled conditions, with MFs on the alga surface and remaining in seawater subsequently counted and characterised. MFs were mainly <2 mm and cellulosic, and contained various additives and chemicals used in textile treatment. Interactions of MFs with U. lactuca were spatially heterogeneous but correcting for pre-existent MFs on the surface, mean trapping efficiencies on a dry mass and surface area basis were 252 mL g-1 and 0.858 mL cm-2, respectively. Despite this heterogeneity, there was evidence of differential trapping based on fibre colour and length. Interactions between the amphiphilic algal surface and MFs are likely both hydrophobic and electrostatic and are not fully reversible, with only ∼30 % of trapped MFs released into clean seawater. Associations with U. lactuca have implications for the transport, fate and ecological impacts of MFs in the coastal zone, and highlight the potential for harvested seaweed to be used in bioremediation.

Effects of functionalized nanoplastics on oxidative stress in the mussel Mytilus coruscus

In the marine environment, various weathering effects on micro or nanoplastics lead to surface modifications, which in turn alter their toxic effects on aquatic organisms. This study investigated the impact of three types of nanoplastics (NPs, NPs-NH2, NPs-COOH) on the antioxidant capacity of Mytilus coruscus gills, mantle, and hemolymph over 28 days. Analyzed key antioxidant stress indicators (CAT, SOD, GSH, GSH-Px, MDA, H2O2) and conducted IBR and PCA analyses to evaluate the toxic effects of modified nanoplastics. In particular, NPs-NH2 showed the most significant inhibition of antioxidant enzymes like CAT and GSH-Px in gills and mantle, while NPs-COOH affected a wider range of oxidative stress markers. Furthermore, tissue-specific responses were observed, with gills being the most sensitive to biomarker changes. Overall, NPs-NH2 emerged as the most toxic nanoplastic, highlighting the need to assess ecological risks associated with novel nanoparticles in marine environments and offering insights into tissue-specific toxicity in mussels.

Limited effects of microplastics on size-fractionated phytoplankton booming in estuarine system

Despite the extensive presence and long-term exposure risks of marine microplastics (MPs), their impact on phytoplankton at the community level is still not very clear, especially considering the various size classes of phytoplankton. To address this issue, we investigated the spatial load of MPs in Linhong Estuary and conducted in-situ experiments of algal culture with added MPs. Our investigation showed that the abundance of MPs varied from 8 n/L to 50 n/L, with an average of 21.76 ± 12.31 n/L. A high loading of MPs was spatially identified outside Linhong Estuary, and clear decreasing trend from land to sea was not observed. Further microscopic examination revealed fiber-shaped MPs dominated in all collections, reaching a proportion of 93%. The chlorophyll a concentrations were 2.69-25.50 μg/L (9.14 ± 6.59 μg/L), 0.68-3.13 μg/L (1.48 ± 0.67 μg/L) and 0.14-0.65 μg/L (0.27 ± 0.14 μg/L) for microphytoplankton (20-200 μm), nanophytoplankton (2-20 μm) and picophytoplankton (0.2-2 μm), respectively. The correlation analysis between MP abundance and chlorophyll a of phytoplankton and the in-situ experiment at an environmentally realistic level both indicated a negative relationship between MP abundance and microphytoplankton with respect to chlorophyll a content, but no adverse effects of MPs were found for nanophytoplankton and picophytoplankton with smaller sizes. Our findings indicate that exposure to realistic levels of MPs only cause a limited impact on size-specific phytoplankton communities studied, but long-term interactions between MPs and these species merit further field-based assessment in real-world scenarios beyond lab-based incubation.

Disentangling the retention preferences of estuarine suspended particulate matter for diverse microplastic types

As a major source of microplastics (MPs) for global oceans, estuarine MPs pose challenges for numerical modeling due to their particle diversity, while hydrodynamics and suspended particulate matter (SPM) further exacerbate transport prediction uncertainties. This study employs a categorization framework to pinpoint 16 representative MPs types, precisely simulating their transport processes in the Yangtze River estuary (YRE). Furthermore, spatial links between SPM concentrations and MP types at 1800+ simulated sites were examined using ArcGIS and bivariate Local Indicators of Spatial Association (BI-LISA). Results indicate that low-density (≤0.95 g/cm³), small-diameter (<500 μm) fiber MPs are more prone to hetero-aggregation with estuarine SPM flocs, while MPs with opposite characteristics may move depending on their intrinsic properties. High-high BI-LISA clusters were observed both in river branches and at the confluence with the sea, the latter closely associated with the turbidity maximum zone that promote MP hetero-aggregation. The interaction of these currents and Yangtze (Changjiang) diluted water forms MPs clusters between 122.0°E and 122.5°E at the confluence of the South Branch, averaging over 870 μg/m3. Examining the trapping preferences of estuarine SPMs for various MPs through this classification framework can help to determine the bioavailability of environmental MPs to aquatic organisms and map the MPs baseline values for health risk quantification.

Plastic ingestion by northern fulmars (Fulmarus glacialis) in the Canadian Arctic and Northwest Atlantic

Plastic pollution is omnipresent in the marine environment, including much of the Arctic. Northern fulmars (Fulmarus glacialis) are particularly vulnerable to ingesting plastics floating on the water's surface, and are an international biomonitor of this contaminant. We sampled plastic ≥1 mm in size from the stomachs of fulmars collected by Inuit hunters in Arctic Canada, as well as beached fulmars from Sable Island, Nova Scotia. The frequency of occurrence (FO) of plastic in Arctic fulmars was 62 % (100 % in Nova Scotia), and mean mass of ingested plastic was 0.027 g, with just two birds from the Arctic (3.4 %) exceeding 0.1 g while all the birds from Sable Island (n = 3) exceeded 0.1 g. This FO was lower than data from previous collections in the Arctic and North Atlantic. Additional monitoring is required to determine whether this reduced FO represents a single year anomaly, or the start of a declining trend.

Field experiment confirms high macroplastic trapping efficiency of wood jams in a mountain river channel

Identifying macroplastic deposition hotspots in rivers is essential for planning cleanup efforts and assessing the risks to aquatic life and the aesthetic value of river landscapes. Recent fieldwork in mountain rivers has shown that wood jams retain significantly more macroplastic than other emergent surfaces within river channels. Here, we experimentally verify these findings by tracking the deposition of 64 PET bottles after 52-65 days of transport in the mid-mountain Skawa River (Polish Carpathians) under low to medium flow conditions. Despite variations in river channel management and the resulting morphological patterns along the study reach, the majority (71.9%, n = 46) of tracked bottles were trapped by wood jams near the low-flow channel. The trapping efficiency was three times higher in the straight, regulated reach (14.8% per km) than in the highly sinuous, unregulated reach (4.5% per km). In the regulated reach, water inundations and wood jams are confined to a narrow zone near the low-flow channel, which may explain the high macroplastic trapping efficiency under low to medium flow conditions. In contrast, in the unmanaged, seminatural reach, where wood jams and water inundation occur over broader areas formed by extensive gravel bars, the trapping potential is lower under similar flow conditions. Previous observations showed that macroplastic deposition hotspots associated with wood jams predominantly form in wide, unmanaged river sections, where numerous jams are inundated during high flows. Our results detail this understanding, suggesting that under low to medium flows, macroplastic hotspots can also form on wood jams in regulated, narrow reaches. These findings suggest that the occurrence of wood jams, channel morphology and past flow conditions are key predictors of macroplastic hotspots formation in mountain rivers.

Mass concentrations, compositions and burial fluxes of nano- and micro-plastics in a multi-species saltmarsh

Plastic pollution poses a serious threat to marine ecosystems; yet quantifying the mass concentrations of nano- and microplastics (NMPs) in saltmarsh sediments at the ocean-land interface remains a critical research gap. Here, the study employed reliable and efficient analytical techniques, namely pressurized liquid extraction and the double-shot model of thermal desorption/pyrolysis-gas chromatography-mass spectrometry, to quantify six different types of NMPs in the sediment of a multi-species saltmarsh, providing the first comprehensive assessment of NMP mass concentration and burial in this saltmarsh environment. The results demonstrate that polyethylene, polyvinyl chloride, and polypropylene dominated the NMP composition in sediments, constituting 72.6%, 17.3%, and 4.5% of the total NMPs, respectively. The measured NMPs represent an anthropogenic intrusion, constituting 0.10%-0.23% of the carbon storage in the saltmarsh. By examining the vertical concentration profiles, this study unveiled the influence of saltmarsh vegetation on NMP deposition in sediments, establishing a connection with local sedimentation patterns and the historical zonation of plant species such as Scirpus mariqueter, Phragmites australis and Spartina alterniflora. These findings underscore the crucial role of saltmarsh vegetation in facilitating NMP settling and retention, highlighting the necessity of considering vegetation dynamics in examining the emerging NMP pollution in coastal wetlands.

Monitoring macroplastics in aquatic and terrestrial ecosystems: Expert survey reveals visual and drone-based census as most effective techniques

Anthropogenic litter, such as plastic, is investigated by the global scientific community from various fields employing diverse techniques. The goal is to assess and finally mitigate the pollutants' impacts on the natural environment. Plastic litter can accumulate in different matrices of aquatic and terrestrial ecosystems, impacting both biota and ecosystem functioning. Detection and quantification of macroplastics, and other litter, can be realized by jointly using visual census and remote sensing techniques. The primary objective of this research was to identify the most effective approach for monitoring macroplastic litter in riverine and marine environments through a comprehensive survey based on the experiences of the scientific community. Researchers involved in plastic pollution evaluated four litter occurrence and flux investigation methods (visual census, drone-based surveys, satellite imagery, and GPS/GNSS trackers) through a questionnaire. Traditional visual census and drone deployment were deemed as the most popular approaches among the 46 surveyed researchers, while satellite imagery and GPS/GNSS trackers received lower scores due to limited field validation and short performance ranges, respectively. On a scale from 0 to 5, visual census and drone-based surveys obtained 3.5 and 2.0, respectively, whereas satellite imagery and alternative solutions received scores lower than 1.2. Visual and drone censuses were used in high, medium and low-income countries, while satellite census and GPS/GNSS trackers were mostly used in high-income countries. This work provides an overview of the advantages and drawbacks of litter investigation techniques, contributing i) to the global harmonization of macroplastic litter monitoring and ii) providing a starting point for researchers and water managers approaching this topic. This work supports the selection and design of reliable and cost-effective monitoring approaches to mitigate the ambiguity in macroplastic data collection, contributing to the global harmonization of macroplastic litter monitoring protocols.

Significant effects of rural wastewater treatment plants in reducing microplastic pollution: A perspective from China's southwest area

Sewage systems are a major source for microplastics in riverine exports to oceans. Urban areas are generally considered hotspots for microplastic discharge, whereas emissions from rural areas remain largely understudied. Hence, this study investigated the abundance, characteristics, and polymer types of microplastics in rural wastewater treatment plants (WWTPs) in Guiyang and estimated the annual microplastic emissions of China based on sewage discharge. The influent abundance of microplastics was 3.8-8.2 items/L, the effluent abundance was 3.1-5.9 items/L, with a lower removal rate of 14.4 %-54.6 %, which might be influenced by lower operating loads and influent concentrations. Raman spectroscopy analysis revealed that polyvinyl alcohol (PVA) was the predominant polymer type. Rural WWTPs were more effective at removing large-sized particles (> 0.1 mm) and films, resulting in higher removal effectiveness by weight (49.1 %) compared to urban WWTPs (30.8 %). Based on the abundance of microplastics in WWTPs within the study area and China's annual sewage discharge, this study estimated the microplastic emissions released through sewage in China in 2022. The annual microplastic emissions through sewage in China were estimated to be 2995.7 tons, with rural and urban areas contributing 25.1 % and 74.9 %, respectively. Approximately 724.8 tons and 1001.6 tons of microplastics were removed from rural and urban WWTPs, respectively. This work indicates the unignorable emissions of microplastics from rural sewage and highlights the crucial role of rural WWTPs in reducing microplastic pollution.

Integrative models for environmental forecasting of phthalate migration from microplastics in aquaculture environments

The pervasive utilization of plastic tools in aquaculture introduces significant volumes of microplastic fibers, presenting a consequential risk through the leaching of additives such as phthalates. This study scrutinizes the leaching dynamics of six prevalent phthalate esters (PAEs) from thirteen plastic aquaculture tools comprising polyethylene terephthalate (PET), polypropylene (PP), and polyethylene (PE), with ΣPAEs ranging from 0.24 to 4.26 mg g-1. Di(2-ethylhexyl) phthalate (DEHP) and dibutyl phthalate (DBP) emerged as predominant, marking significant environmental concern. Over a 30-day period, leaching quantities of Σ6PAEs from PET, PP, and PE fibers reached 36.65 μg g-1, 21.87 μg g-1 and 19.11 μg g-1, respectively, influenced by factors such as time, temperature, turbulence, and salinity. Notably, turbulence exerted the most pronounced effect, followed by temperature, with negligible influence from salinity. The kinetic models aligning with interface diffusion control was developed, predicting PAEs' leaching behavior with activation energies (Ea) indicative of the process's thermodynamic nature. The application of this model to real-world aquaculture waters forecasted significant risks, corroborating with empirical data and underscoring the pressing need for regulatory and mitigation strategies against PAEs contamination from aquaculture practices.

Assessment of microplastic pollution and polymer risk in the sediment compartment of the Limfjord, Denmark

Estuarine sediments intercept and temporarily retain microplastics before they reach the marine seafloor, impacting various organisms, including key commercial species. This highlights the critical need for research on microplastic exposure in these transitional environments. This study provides a detailed assessment of microplastic pollution in the sediment compartment of the Limfjord, a 1500 km2 large Danish fjord, and introduces the Polymer Hazard Index (PHI) as a tool for evaluating polymer-specific risks. Thirteen sediment samples were collected, covering an anthropogenic gradient along the fjord. State-of-the-art methods were applied for extracting and identifying (FPA-μFT-IR imaging) microplastics (10-5000 μm). Our results indicate that microplastic contamination is pervasive across all sampled locations with concentrations ranging from 273 to 4288 particles kg-1, with a predominance of small microplastics (<100 μm). The estimated mass-based concentrations ranged between 2.60 × 104-1.11 × 106 ng kg-1. Overall, we estimated a microplastic stock of 3.8 × 103-1.65 × 105 kg in the surface sediments of the Limfjord, i.e., some 2.5-110 kg km-2. The application of the PHI revealed significant risks associated with specific polymers, such as polyacrylonitrile (PAN) and acrylonitrile butadiene styrene (ABS), underscoring the importance of considering polymer-specific hazards in environmental assessments.

Barau's petrel, Pterodroma baraui, as a bioindicator of plastic pollution in the South-West Indian Ocean: A multifaceted approach

Marine plastic pollution is well described by bioindicator species in temperate and polar regions but remains understudied in tropical oceans. We addressed this gap by evaluating the seabird Barau's petrel as bioindicator of plastic pollution in the South-West Indian Ocean. We conducted a multifaceted approach including necropsies of birds to quantify plastic ingestion; GPS tracking of breeding adults to identify their foraging areas; manta trawling of plastic debris to measure plastic pollution at sea and modelling of plastic dispersal. We developed a spatial risk index of seabird exposure to plastic ingestion. Seventy-one percent of the analysed birds had ingested plastic. GPS tracking coupled with manta trawling and dispersal modelling show that adults consistently foraged at places with high level of plastic concentration. The highest ingestion risk occurred in the northwest of Reunion Island and at latitude 30°S. Our findings confirm that Barau's petrel is a reliable bioindicator of plastic pollution in the region.

Future Scenarios for River Exports of Multiple Pollutants by Sources and Sub-Basins Worldwide: Rising Pollution for the Indian Ocean

In the future, rivers may export more pollutants to coastal waters, driven by socio-economic development, increased material consumption, and climate change. However, existing scenarios often ignore multi-pollutant problems. Here, we aim to explore future trends in annual river exports of nutrients (nitrogen and phosphorus), plastics (macro and micro), and emerging contaminants (triclosan and diclofenac) at the sub-basin scale worldwide. For this, we implement into the process-based MARINA-Multi model (Model to Assess River Inputs of pollutaNts to the seAs) two new multi-pollutant scenarios: "Sustainability-driven Future" (SD) and "Economy-driven Future" (ED). In ED, river exports of nutrients and microplastics will double by 2100, globally. In SD, a decrease of up to 83% is projected for river export of all studied pollutants by 2100, globally. Diffuse sources such as fertilizers are largely responsible for increasing nutrient pollution in the two scenarios. Point sources, namely sewage systems, are largely responsible for increasing microplastic pollution in the ED scenario. In both scenarios, the coastal waters of the Indian Ocean will receive up to 400% more pollutants from rivers by 2100 because of growing population, urbanization, and poor waste management in the African and Asian sub-basins. The situation differs for sub-basins draining into the Mediterranean Sea and the Pacific Ocean (mainly less future pollution) and the Atlantic Ocean and Arctic Ocean (more or less future pollution depending on sub-basins and scenarios). From 56% to 78% of the global population are expected to live in more polluted river basins in the future, challenging sustainable development goals for clean waters.

Genome-Wide Molecular Adaptation in Algal Primary Productivity Induced by Prolonged Exposure to Environmentally Realistic Concentration of Nanoplastics

Little information is known about the long-term effects of nanoplastics (NPs) in aquatic environments, especially under environmental-related scenarios. Herein, three differently charged NPs (nPS, nPS-NH2, and nPS-COOH) were exposed at an environmentally realistic concentration (10 μg/L) for 100 days to explore the variation of primary productivity (i.e., algae) in aquatic ecosystems. Our results demonstrated that the algae adapted to all three types of NPs by enhancing the algal number (by 10.34-16.52%), chlorophyll a (by 11.28-17.65%), and carbon-fixing enzyme activity (by 49.19-68.33%), which were further confirmed by the exposure results from natural water culturing experiments. Based on the algal chloroplast number and biovolume at the individual level, only nPS caused algal differentiation into two heterogeneous subpopulations (54.92 vs 45.08%), while nPS-NH2 and nPS-COOH did not cause the differentiation of the algal population. Moreover, the molecular adaptation mechanisms of algae to NPs were unraveled by integrating epigenomics and transcriptomics. Mean methylation rates of algae on exposure to nPS, nPS-NH2, and nPS-COOH were significantly elevated. In addition, the direction of gene expression regulation via differentially methylated regions associated with genes when exposed to nPS-COOH was distinct from those of nPS and nPS-NH2. Our results highlight the importance of assessing the long-term ecotoxicity of NPs and provide useful information for understanding the effect of NPs on aquatic ecosystems.

Oceanic realistic application of a microplastic biofouling model to the river discharge case

Marine biofouling is considered one of the major biophysical processes influencing the vertical dynamics of plastic debris in seawater. We numerically implement, for the first time, this mechanism within a fine-resolution, regional model of the Tyrrhenian Sea, in order to simulate the dispersion of microplastics (MPs) released at the mouth of a highly polluting river. Four polymers and three particle sizes are used to quantify algal concentration influence on the trajectories, fates, and accumulation spots of the tracked MPs, by comparing 2002 winter and summer runs encompassing or not biofouling. Besides a marked seasonality for most of the MP types and radii tested, biofouling effects are prominently observed for only 2 polymers and particles bigger than 1μm. Thus, further realistic applications of the biofouling mechanism in oceanic circulation models are required to achieve a thorough assessment of its impact on plastic density within distinctive basins of the world seas.

Microplastics in wild fish in the Three Gorges Reservoir, China: A detailed investigation of their occurrence, characteristics, biomagnification and risk

Microplastics (MPs) pollution in freshwater poses a risk to various ecosystems and health security. In 2018, the Chinese government banned fishing since 2018 in the Three Gorges Reservoir (TGR), but the fate and risk of MPs in wild fish remain unclear. Therefore, a detailed investigation was conducted into the occurrence of MPs in 18 wild fish species in the TGR using a Micro Fourier Transform Infrared Spectrometer, and the trophic transfer and risks were assessed. MPs in fish were aged, with abundances ranging from 0.68 ± 0.98 to 4.00 ± 2.12 items/individual. Most particles were less than 1 mm in size (73.4 %), with fibers being the dominant shape (48.9 %) and transparent as the dominant color (35 %). Polyethylene (PE) was the most prevalent type. The bioconcentration factor (BCF), bioaccumulation factor (BAF), trophic magnification factor (TMF) and polymer hazard index (PHI) were low, suggesting no trophic transfer and a low risk of MPs. The BAF may provide a more reasonable description of the degree of enrichment of MPs, and 'items/individual' or 'g/individual' can be used to describe MPs concentrations in fish. This study proposes new insights and prospectives that can help researchers better understand MPs enrichment in fish across various trophic levels.

Hormesis of black soldier fly larva: Influence and interactions in livestock manure recycling

Black soldier fly larvae (BSFL) are considered important organisms, utilized as tools to transform waste including manure into valuable products. The growth and cultivation of BSFL are influenced by various factors, such as the presence of toxic substances in the feed and parasites. These factors play a crucial role in hormesis, and contributing to regulate these contaminants hermetic doses to get sustainable byproducts. This review aims to understand the effects on BSFL growth and activities in the presence of compounds like organic and inorganic pollutants. It also assesses the impact of microbes on BSFL growth and explores the bioaccumulation of pharmaceutical compounds, specifically focusing on heavy metals, pesticides, pharmaceuticals, indigenous bacteria, insects, and nematodes. The review concludes by addressing knowledge gaps, proposing future biorefineries, and offering recommendations for further research.

Do birds select the plastics debris used for nest construction? A case study in a Mediterranean agricultural landscape

Plastic pollution is becoming a global problem due to its ubiquitous occurrence and the impacts detected for many species. However, the research about plastics in nests of terrestrial bird species has remained relatively overlooked in comparison to those devoted to marine ecosystems. Here we study the occurrence and patterns of use of anthropogenic material in nests of two passerine birds, the Eurasian magpie (Pica pica) and the European serin (Serinus serinus), breeding in an orange tree cultivation in Mediterranean Spain. Our results show that both species use extensively plastic debris as nest material; almost 71% of the European serin nests and 96% of nests of Eurasian magpies contained plastic debris. Furthermore, by analyzing the plastic debris availability in the agricultural landscape surveyed we confirmed a selection pattern in the two species. Thus, both species preferably select plastic filaments over other plastic debris. The Eurasian magpie does not select plastic based on size or color but the European serin avoid black plastics prefer smaller fragments in comparison to the average size available. Moreover, we suggest the apparent similarity of plastic filaments with the natural materials typically used by these species, as well as how they use the plastic in their nests could influence their selection behavior. More studies focused on terrestrial birds inhabiting human modified habitats could offer a deeper approach to how plastic debris interacts with wildlife in different ways.

Environmental fate of microplastics in high-altitude basins: the insights into the Yarlung Tsangpo River Basin

Microplastics (MPs) have been found in remote high-altitude areas, but the main source and migration process remained unclear. This work explored the characteristics and potential sources of MPs in the Yarlung Tsangpo River Basin. The average abundances of MPs in water, sediment, and soil samples were 728.26 ± 100.53 items/m3, 43.16 ± 5.82 items/kg, and 61.92 ± 4.29 items/kg, respectively, with polypropylene and polyethylene as the main polymers. The conditional fragmentation model revealed that the major source of MPs lower than 4000 m was human activities, while that of higher than 4500 m was atmospheric deposition. Community analysis was further conducted to explore the migration process and key points of MPs among different compartments in the basin. It was found that Lhasa (3600 m) and Shigatse (4100 m) were vital sources of MPs inputs in the midstream and downstream, respectively. This work would provide new insights into the fate of MPs in high-altitude areas.

Microplastic pollution differences in freshwater river according to stream order: Insights from spatial distribution, annual load, and ecological assessment

Microplastic (MP) pollution has become a pressing concern in global freshwater ecosystems because rivers serve as essential channels for the transport of terrestrial debris to the ocean. The current researches mostly focus on the large catchments, but the impact on the small catchments remains underexplored. In this study, we employed Strahler's stream order classification to delineate the catchment structure of the Beijiang River in South China. The distribution pattern of MP contamination and the factors influencing the distribution pattern, were assessed across the streams at different orders. We found that the Beijiang River was moderately polluted compare to other rivers in China, with an average MP abundance of 2.15 ± 1.65 items/L. MP abundance ranged from 3.17 to 1.45 items/L in the streams at different orders, and significantly decreased with increasing stream order (R2 = 0.93). This highlights the key role of small rivers as the channels for the transport of MPs from watersheds to main streams. The high abundance of PP and PE fibers, the high correlation between the stream order and the resin proportion (R2 = 0.89), and the significant correlation between MP abundance and proximity to urban centers (P = 0.02), indicated that MP pollution across the streams at different orders was predominantly influenced by anthropogenic activities, rather than natural environmental factors. By integrating MP data with hydrographic information, the annual MP loads for the streams at Orders 1 to Order 5 were estimated to be 4.63, 39.38, 204.63, 503.06, and 1137.88 tons/yr, respectively. Additionally, an ecological risk assessment indicates that MP pollution led to a low risk in the Beijiang River. Our findings deepen the understanding of MP pollution within freshwater river networks, and emphasize the crucial role of tributary systems in transporting MPs to main river channels.

Seasonal dynamics, tidal influences, and anthropogenic impacts on microplastic distribution in the Yangtze River estuary: A comprehensive characterization and comparative analysis

Microplastics (MPs) are emerging contaminants with significant ecological and human health implications. This study examines the abundance, characteristics, and distribution of MPs in the Yangtze River estuary, focusing on seasonal variations, tidal cycles, and anthropogenic influences. Surface samples were collected using the Manta trawl method to ensure consistency with previous marine MP research. The study found an average MP concentration of 1.01 (± 0.65) n m-3, predominantly comprising low-density polymers such as polystyrene (38 %), polypropylene (33 %), and polyethylene (29 %). MPs were mainly fragments (34.9 %) and foam (30.7 %), with a prevalence of white particles. Seasonal analysis indicated significantly higher MP concentrations during flood seasons (1.32 ± 1.09 n m-3), nearly 1.9 times higher than during non-flood seasons (0.70 ± 0.28 n m-3). Tidal cycles also impacted MP distribution, with ebb tides showing increased concentrations (2.44 ± 1.30 n m-3) compared to flood tides (1.48 ± 2.07 n m-3). Furthermore, MP abundance showed a decreasing trend with increasing distance from urban centers, with significant correlations (0.52 < R2 < 0.65, P < 0.001). These findings underscore the necessity for seasonally adjusted monitoring and robust management strategies to combat MP pollution. The study advocates for the integration of diverse sampling methods and the consideration of environmental factors in future MP assessments, laying the groundwork for understanding the MP transport mechanism in the Yangtze River estuary and similar estuarine systems worldwide.

Polystyrene Nanoplastics Induce Lipid Metabolism Disorder by Activating the PERK-ATF4 Signaling Pathway in Mice

In recent years, the study of microplastics (MPs) and nanoplastics (NPs) and their effects on human health has gained significant attention. The impacts of NPs on lipid metabolism and the specific mechanisms involved remain poorly understood. To address this, we utilized high-throughput sequencing and molecular biology techniques to investigate how endoplasmic reticulum (ER) stress might affect hepatic lipid metabolism in the presence of polystyrene nanoplastics (PS-NPs). Our findings suggest that PS-NPs activate the PERK-ATF4 signaling pathway, which in turn upregulates the expression of genes related to lipid synthesis via the ATF4-PPARγ/SREBP-1 pathway. This activation leads to an abnormal accumulation of lipid droplets in the liver. 4-PBA, a known ER stress inhibitor, was found to mitigate the PS-NPs-induced lipid metabolism disorder. These results demonstrate the hepatotoxic effects of PS-NPs and clarify the mechanisms of abnormal lipid metabolism induced by PS-NPs.

Significant regional disparities in riverine microplastics

Research on riverine microplastics has gradually increased, highlighting an area for further exploration: the lack of extensive, large-scale regional variations analysis due to methodological and spatiotemporal limitations. Herein, we constructed and applied a comprehensive framework for synthesizing and analyzing literature data on riverine microplastics to enable comparative research on the regional variations on a large scale. Research results showed that in 76 rivers primarily located in Asia, Europe, and North America, the microplastic abundance of surface water in Asian rivers was three times higher than that in Euro-America rivers, while sediment in Euro-American rivers was five times more microplastics than Asia rivers, indicating significant regional variations (p < 0.001). Additionally, based on the income levels of countries, rivers in lower-middle and upper-middle income countries had significantly (p < 0.001) higher abundance of microplastics in surface water compared to high-income countries, while the opposite was true for sediment. This phenomenon was preliminarily attributed to varying levels of urbanization across countries. Our proposed framework for synthesizing and analyzing microplastic literature data provides a holistic understanding of microplastic disparities in the environment, and can facilitate broader discussions on management and mitigation strategies.

Among-colony variation in plastic ingestion by Yellow-legged gulls (Larus michahellis) across the western Mediterranean basin

The Mediterranean region is both a hotspot for biodiversity and for the accumulation of plastic pollution. Many species are exposed to this pollution while feeding, including a wide diversity of seabirds. Our objective was to investigate spatial variation in the quantity and types of plastic ingested by Yellow-legged gulls using information obtained from regurgitated pellets collected in 11 colonies. Anthropogenic debris, and particularly plastic, was found in pellets from all colonies, but the amount varied considerably. This among-colony difference was stable over the two years of study. The presence of marine prey and the proportion of agricultural area around the colonies significantly influenced the number of ingested plastics. As landfills close and garbage management improves, the availability of anthropogenic waste should decline. Following the response of gulls to these changes will be particularly useful for monitoring plastic pollution and for understanding the response of opportunistic wildlife to environmental modifications.

Rapid Mass Conversion for Environmental Microplastics of Diverse Shapes

Rivers have been recognized as the primary conveyors of microplastics to the oceans, and seaward transport flux of riverine microplastics is an issue of global attention. However, there is a significant discrepancy in how microplastic concentration is expressed in field occurrence investigations (number concentration) and in mass flux (mass concentration). Of urgent need is to establish efficient conversion models to correlate these two important paradigms. Here, we first established an abundant environmental microplastic dataset and then employed a deep neural residual network (ResNet50) to successfully separate microplastics into fiber, fragment, and pellet shapes with 92.67% accuracy. We also used the circularity (C) parameter to represent the surface shape alteration of pellet-shaped microplastics, which always have a more uneven surface than other shapes. Furthermore, we added thickness information to two-dimensional images, which has been ignored by most prior research because labor-intensive processes were required. Eventually, a set of accurate models for microplastic mass conversion was developed, with absolute estimation errors of 7.1, 3.1, 0.2, and 0.9% for pellet (0.50 ≤ C < 0.75), pellet (0.75 ≤ C ≤ 1.00), fiber, and fragment microplastics, respectively; environmental samples have validated that this set is significantly faster (saves ∼2 h/100 MPs) and less biased (7-fold lower estimation errors) compared to previous empirical models.

Proof of concept for a new sensor to monitor marine litter from space

Worldwide, governments are implementing strategies to combat marine litter. However, their effectiveness is largely unknown because we lack tools to systematically monitor marine litter over broad spatio-temporal scales. Metre-sized aggregations of floating debris generated by sea-surface convergence lines have been reported as a reliable target for detection from satellites. Yet, the usefulness of such ephemeral, scattered aggregations as proxy for sustained, large-scale monitoring of marine litter remains an open question for a dedicated Earth-Observation mission. Here, we track this proxy over a series of 300,000 satellite images of the entire Mediterranean Sea. The proxy is mainly related to recent inputs from land-based litter sources. Despite the limitations of in-orbit technology, satellite detections are sufficient to map hot-spots and capture trends, providing an unprecedented source-to-sink view of the marine litter phenomenon. Torrential rains largely control marine litter inputs, while coastal boundary currents and wind-driven surface sweep arise as key drivers for its distribution over the ocean. Satellite-based monitoring proves to be a real game changer for marine litter research and management. Furthermore, the development of an ad-hoc sensor can lower the minimum detectable concentration by one order of magnitude, ensuring operational monitoring, at least for seasonal-to-interannual variability in the mesoscale.

Challenges and Recent Analytical Advances in Micro/Nanoplastic Detection

Despite growing ecological concerns, studies on microplastics and nanoplastics are still in their initial stages owing to technical hurdles in analytical techniques, especially for nanoplastics. We provide an overview of the general attributes of micro/nanoplastics in natural environments and analytical techniques commonly used for their analysis. After demonstrating the analytical challenges associated with the identification of nanoplastics due to their distinctive characteristics, we discuss recent technological advancements for detecting nanoplastics.