Are we underestimating microplastic abundance in the marine environment? A comparison of microplastic capture with nets of different mesh-size

Finding the Balance between Research and Monitoring: When Are Methods Good Enough to Understand Plastic Pollution?

Plastic pollution is an international environmental problem. Desire to act is shared from the public to policymakers, yet motivation and approaches are diverging. Public attention is directed to reducing plastic consumption, cleaning local environments, and engaging in citizen science initiatives. Policymakers and regulators are working on prevention and mitigation measures, while international, regional, and national bodies are defining monitoring recommendations. Research activities are focused on validating approaches to address goals and comparing methods. Policy and regulation are eager to act on plastic pollution, often asking questions researchers cannot answer with available methods. The purpose of monitoring will define which method is implemented. A clear and open dialogue between all actors is essential to facilitate communication on what is feasible with current methods, further research, and development needs. For example, some methods can already be used for international monitoring, yet limitations including target plastic types and sizes, sampling strategy, available infrastructure and analytical capacity, and harmonization of generated data remain. Time and resources to advance scientific understanding must be balanced against the need to answer pressing policy issues.

Microplastics pollution in the rivers of a metropolitan city and its estimated dependency on surrounding developed land

The spatial distribution and abundance of suspected microplastics (SMPs) in the surface water of a metropolitan city, as represented by four Hong Kong rivers, was studied during the dry season. Shing Mun River (SM), Lam Tsuen River (LT), and Tuen Mun River (TM) are located in urbanized areas, and SM and TM are tidal rivers. The fourth river, Silver River (SR) is situated in a rural area. TM had a significantly higher SMP abundance (53.80 ± 20.67 n/L) than the other rivers. The SMP abundance increased from upstream to downstream in non-tidal rivers (LT and SR), but not in tidal rivers (TM and SM), probably due to the tidal influence and a more homogeneous urban development along the tidal rivers. Inter-site differences in the SMP abundance were strongly correlated with the built area ratio (defined as the percentage of surrounding developed land area), human activities, and the nature of the river. About half (48.72 %) of the SMPs were <250 μm. Fibers and fragments were most abundant (>98 %), with most of them being transparent (58.54 %), black (14.68 %), or blue (12.12 %). Polyethylene terephthalate (26.96 %) and polyethylene (20.70 %) were the most common polymers. However, the MP abundance could be overestimated due to the presence of natural fibers. By contrast, an underestimation of the MP abundance could result from a smaller volume of water samples collected, due to a low filtration efficiency caused by high organic content and particle concentrations in the water. A more effective solid waste management strategy and upgrading of the sewage treatment facilities for removing microplastics are recommended to ameliorate the microplastic pollution in local rivers.

First evidence of microplastics in freshwater from fish farms in Rondônia state, Brazil

The main aimed of this study was to provide information on microplastics present in the freshwater of fish farm ponds. In addition, the study showes a relationship between the seasonal, spatial distribution and the amount of microplastics found. This study was conducted in 35 fish farms located in the Rondônia state, Brazil, the sample collects were carried out in the two Amazonian hydrological seasons (dry and rainy). The study was developed in a completely randomized factorial scheme 35 × 3 x 3 (35 fish farms, 3 ponds and 3 repetitions per ponds). Microplastic sampling was performed following a modified method based on National Oceanic and Atmospheric Administration (NOAA). Samples of 250 mL freshwater collected, which were deionized and pre-filtered through 6.0 mm mesh granulometric sieves. The average abundances of the different hydrological seasons were compared by Student's t-test, with differences statistically significant at p < 0.05. The microplastics were morphological categorized into fibers and colors blue, red or transparent. Microplastic contamination was confirmed in freshwater of 9 fish farming, with greater abundance of blue fibers and greater quantification in the rainy season. Fish farms P3, P4 and P6 had the highest quantifications of blue fiber in the two seasons (6 and 43, 19 and 56, 11 and 88 items mL^-1, respectively). Almost all fish farms had a higher abundance of microplastics in the rainy season. It is important to highlight the prominence of microplastics in the blue fiber rainy season (286 items mL^-1) compared to the dry season (58 items mL^-1). Fish farms P3, P4 and P6 showed a strong positive correlation between the factors distance from the nearest urban area (r = 0.94, 0.79 and 0.97, respectively) and seasonality (r = 0.98, 0.77 and 0.96, respectively). Rainfall variations influenced the abundance of microplastics, especially of blue fibers. Fish farms are supplied with fresh water by rivers or streams, so it is possible that microplastics originate outside the fish farm, perhaps they were introduced due to high soil occupation, although surface runoff (of water contaminated by sewage) caused by heavy rains the most important factor. Therefore, one factor must be considered, surface runoff and groundwater contaminated by urban, agricultural and urban effluents may have contaminated rivers and streams and then contaminated the water in the fish farm ponds.

Exploration of occurrence and sources of microplastics (>10 μm) in Danish marine waters

Microplastics (MPs) were quantified in Danish marine waters of the Kattegat and the southernmost part of Skagerrak bordering to it. Kattegat is a waterbody between Denmark and Sweden that receives inflow from the Baltic Sea and direct urban runoff from the metropolitan area of Copenhagen and Malmö. MPs were measured in 14 continuous transects while steaming between monitoring stations. MP levels tended to be highest close to the Copenhagen-Malmö area, albeit this was more obvious from the abundance of particles rather than mass. The outcome of the measurements allowed a rough MP budget in the Danish Straits region, suggesting that urban waste- and stormwater discharges could not be neglected as potential MP source in these waters. The marine samples were collected by pumping and filtering water over 10 μm steel filters, hereby sampling a total of 19.3 m³. They were prepared and analyzed by FPA-μFTIR imaging, and the scans interpreted to yield MP size, shape, polymer type, and estimated mass. The average concentration was 103 ± 86 items m^-3, corresponding to 23.3 ± 28.3 μg m^-3 (17-286 items m^-3; 0.6-84.1 μg m^-3). Most MPs were smaller than 100 μm and fragments dominated the samples. The carbonyl index was assessed for polyolefins, showing that oxidation increased with decreasing MP size, but did not correlate with distance to urban areas. A rough budget of MP in the Danish Straits region suggested that MPs discharged from urban waste- and stormwaters were an import source of MPs.

Rapid shipboard measurement of net-collected marine microplastic polymer types using near-infrared hyperspectral imaging

Isolation and detection of microplastics (MP) in marine samples is extremely cost- and labor-intensive, limiting the speed and amount of data that can be collected. In the current work, we describe rapid measurement of net-collected MPs (net mesh size 300 µm) using a benchtop near-infrared hyperspectral imaging system during a research expedition to the subtropical North Atlantic gyre. Suspected plastic particles were identified microscopically and mounted on a black adhesive background. Particles were imaged with a Specim FX17 near-infrared linescan camera and a motorized stage. A particle mapping procedure was built on existing edge-finding algorithms and a polymer identification method developed using spectra from virgin polymer reference materials. This preliminary work focused on polyethylene, polypropylene, and polystyrene as they are less dense than seawater and therefore likely to be found floating in the open ocean. A total of 27 net tows sampled 2534 suspected MP particles that were imaged and analyzed at sea. Approximately 77.1% of particles were identified as polyethylene, followed by polypropylene (9.2%). A small fraction of polystyrene was detected only at one station. Approximately 13.6% of particles were either other plastic polymers or were natural materials visually misidentified as plastics. Particle size distributions for PE and PP particles with a length greater than 1 mm followed an approximate power law relationship with abundance. This method allowed at-sea, near real-time identification of MP polymer types and particle dimensions, and shows great promise for rapid field measurements of microplastics in net-collected samples.

Microplastics in the riverine environment: Meta-analysis and quality criteria for developing robust field sampling procedures

Current sampling approaches for quantifying microplastics (MP) in the riverine water column and riverbed are unstandardised and fail to document key river properties that impact on the hydrodynamic and transport processes of MP particles, hindering our understanding of MP behaviour in riverine systems. Using ten criteria based on the reportage of the catchment area, river characteristics of sampling sites and approach, we reviewed the sampling procedures employed in 36 field-based river studies that quantify MP presence in the water column and benthic sediment. Our results showed that a limited number of studies conducted reliable sampling procedures in accordance with the proposed quality criteria, with 35 of the 36 studies receiving a score of zero for at least one criterion, indicating the omission of critical information relating to the study's sample size and the physical and hydraulic characteristics of the sampled river. On the other hand, a good number of studies adequately documented the spatial information of the sampling sites, the vertical location of sample collection, and sampling equipment used. An idealised MP sampling approach is presented to ensure that future studies are harmonised and variables underpinning MP transport in rivers are reported. In addition, a meta-analysis on MP particle characteristics from these studies found that concentrations in the riverine water column and benthic sediment are highly variable, varying by five and seven orders of magnitude respectively, and are heavily dependent on the sampling equipment used. Polypropylene (PP), polyethene, (PE), polystyrene (PS), polyethylene terephthalate (PET) and polyvinyl chloride (PVC) were the most frequently reported MP polymers, while irregular-shaped particles, fibres, spheres, and films were the most commonly reported shapes in the river studies. These results highlight the urgent need to standardise sampling procedures and include key contextual information to improve our understanding of MP behaviour and transport in the freshwater environment.

Formation of microplastic fibers and fibrils during abrasion of a representative set of 12 polyester textiles

Microplastic fibers (MPFs) released from synthetic textiles have been found to be a major source of microplastic in the environment. There is increasing evidence available that MPFs released during washing were likely formed during the manufacturing stage. However, real-life use of textiles is often associated with textile-on-textile abrasion, and the first evidence is available that MPFs and finer microplastic fiber fragments (fibrils) are formed during abrasion. In this study, we characterized the formation of MPFs and fibrils from a representative set of 12 polyester textiles after abrasion tests conducted with a Martindale tester. We also investigated the influence of rub intensity and the extractability of MPFs and fibrils from the abraded fabrics. For all textiles, the MPFs extracted after abrasion showed the same diameter as the fibers in non-abraded textiles (10-20 μm), while the extracted fibrils were much thinner (3-5 μm). The variability in the structure of the different polyester textiles led to a broad range of MPF and fibrils extracted during the first wash after 5000 rubs. One gram of textile released between 4900 and 640,000 MPFs and between 0 and 350,000 fibrils with an average fibril/MPF ratio of 0.8. The total number of MPFs and fibrils formed during abrasion was positively correlated with the increase in the number of rubs up to 10,000 times. Visible pilling on the textile surface was an important indicator for the formation of MPFs and fibrils. Our study revealed that textile abrasion is a critical, realistic, and overlooked mechanism for the formation of MPFs and fibrils, as abraded textiles (after 5000 times rubs) can release more than ten times the number of MPFs and fibrils compared to washing only.

Microplastic levels on sandy beaches: Are the effects of tourism and coastal recreation really important?

This study assessed the effect of tourism and other recreational activities on microplastic (MP) levels and their characteristics in the sand and surf zone of the seawater. Six sites were chosen belonging to three sandy beaches with similar geomorphologic and morphodynamic characteristics but with different tourism activities. On average, a concentration of 1133.3 ± 811.3 items/kg dry weight (d.w.) and 12.7 ± 14.9 items/m³ were found in the sand and seawater samples, respectively. Fibers and films predominated and were less than 1 mm in length. In the sand, the films mainly matched the PE polymer spectra and the fibers matched PET polymer, cotton, and indigo blue dye; in the seawater samples, PP films and PET fibers prevailed. At the Pehuén-Co - Monte Hermoso Coastal Marine MPA where the flow of tourists is low, the MP levels were the lowest and the largest particles were found, mainly blue or black fibers, with less polymer diversity, cotton and PET being the most prevalent suggesting a recent input of textile fibers to this site. Moreover, the highest concentration of MPs was found on the southern site of a beach considered to be more pristine due to negligible human activity, including the smallest size pattern, mostly composed of white films or fibers with a greater diversity of polymers, predominantly PE > PET > PP. A great occurrence of PVC white films was also found in the surf zone at this site. Proximity to the mouth of a river, littoral drift, and other point sources were identified as the main sources, indicating that, apart from the local tourism and recreational activities, other sources might play a major role in the input of MPs to sandy beaches, such as extensive/intensive agricultural land use and irrigation areas.

Contamination from microplastics and other anthropogenic particles in the digestive tracts of the commercial species Engraulis encrasicolus and Sardina pilchardus

Fragments of microplastics (<5 mm) found in commercial species of fish, crustaceans, and bivalves, are an issue of global concern. The bioaccumulation of microplastics and other anthropogenic particles in different levels of the food web may provoke unwanted impacts on marine ecosystems and cause pernicious effects on human health. Here, we study the presence of anthropogenic particles and the fraction of microplastics in the target organs of two representative commercial fish species in Spain; the European anchovy (Engraulis encrasicolus) and the European pilchard (Sardina pilchardus). The individuals were sampled along the continental shelf of the Gulf of Cádiz, from the Bay of Cádiz to Cape Santa Maria. The isolation of the microplastics (MPs) was carried out with a complete alkaline-oxidant organic digestion (KOH-H₂O₂) of the digestive tract, including both the contents ingested and the muscle tissues. Anthropogenic particles were found in all individuals of both species with an average of 8.94 ± 5.11 items·ind^-1. Fibres made up 93 % of the items while fragments and films were represented by the remaining 7 %. The average size of the anthropogenic particles was 0.89 ± 0.82 mm. In addition to the fragment and film particles identified as microplastics, 29 % of the fibres were estimated to be microplastics by Fourier-transform infrared spectroscopy (FTIR) analysis. The main polymer found in both species was nylon. No significant correlation was found between the abundance and size of anthropogenic particles ingested and individual size or other body variables. The analysis of similarities (ANOSIM) and the distanced-based multiple linear regression model showed a high homogeneity in anthropogenic particle contamination in both species throughout the study area along the continental shelf of the Gulf of Cádiz.

A novel framework-based meta-analysis for in-depth characterization of microplastic pollution and associated ecological risks in Chinese Bays

Among aquatic ecosystems, bays are ubiquitously contaminated with microplastics (MPs, size <5 mm), but a comprehensive understanding of their pollution characterization in Chinese Bays is largely elusive. The current study aims to systematically highlight factors intricating MP contamination as well as their geographic distribution, interactions, risk evaluation, and abundance prediction in bays. MPs' abundance was varied in different bays, at concentrations ranging between 0.26 ± 0.14-89, 500 ± 20, 600 items/m³ in water, 15 ± 6-6433.5 items/kg dry weight in sediment and 0.21 ± 0.10-103.5 items/individual in biota. Redundancy analysis, Permannova, and GeoDetector model revealed that the sampling and extraction/identification methods, and geographical locations were the major drivers affecting MP distribution and characteristics. The Mantel test highlighted that the MP characteristics changed with geographic distance, higher in water than that in sediment and biota. ANOSIM results showed that the different environmental media exhibit significant differences in MP characteristics (e.g., color, shape, and polymer). The ARIMA model predicted that Sanggou Bay and Hangzhou Bay have a higher potential for significantly increasing MP contamination in the future. The highest hazard index (HI) values for water, sediment, and biota were respectively reported at Jiaozhou Bay (18,844.16), Bohai Bay (11,485.37), and Dongshan Bay (48,485.11). The highest values for the ecological risk index (RI) in water, sediment, and biota were detected at Beibu Gulf (6,129,559.02), Haikou Bay (2229.14), and Dongshan Bay (561,563.05), respectively. Overall, this framework can be used at different scales and in different environments, which makes it useful for understanding and controlling MP pollution in the ecosystem.

Taking control of microplastics data: A comparison of control and blank data correction methods

Although significant headway has been achieved regarding method harmonisation for the analysis of microplastics, analysis and interpretation of control data has largely been overlooked. There is currently no consensus on the best method to utilise data generated from controls, and consequently many methods are arbitrarily employed. This study identified 6 commonly implemented strategies: a) No correction; b) Subtraction; c) Mean Subtraction; d) Spectral Similarity; e) Limits of detection/ limits of quantification (LOD/LOQ) or f) Statistical analysis, of which many variations are possible. Here, the 6 core methods and 45 variant methods (n = 51) thereof were used to correct a dummy dataset using control data. Most of the methods tested were too inflexible to account for the inherent variation present in microplastic data. Only 7 of the 51 methods tested (six LOD/LOQ methods and one statistical method) showed promise, removing between 96.3 % and 100 % of the contamination data from the dummy set. The remaining 44 methods resulted in deficient corrections for background contamination due to the heterogeneity of microplastics. These methods should be avoided in the future to avoid skewed results, especially in low abundance samples. Overall, LOD/LOQ methods or statistical analysis comparing means are recommended for future use in microplastic studies.

Current levels and composition profiles of microplastics in irrigation water

Land-based sources have been considered the most important sources of microplastic pollution to the coastal and marine environment. The number of research studies examining microplastic pollution in freshwater and inland water systems is increasing, but most research focuses on rivers, reservoirs, and lakes. This study investigated the spatial-temporal distribution, characteristics, sources, and risks of microplastics in irrigation water in Taiwan. The results showed that microplastics were widely and unevenly distributed along the irrigation system and were abundant at sites surrounded by a dense population and sites that received lateral canal and urban runoff input. The abundance of microplastics ranged from 1.88 items/L to 141 items/L, and samples collected in May had the highest microplastic concentrations. Polypropylene, polyethylene, and polystyrene were identified as the predominant polymers. Fibers (36-64%) were the most typical and abundant shape, and 333-1000 μm size (49-63%) and white/transparent (45-51%) were the dominant size and colors among all samples. Principal component analysis (PCA) and hierarchical cluster analysis (HCA) were used to assess the impact of the rainy season and typhoons and addressed the dramatic changes in distinct population densities. The polymer risk index was calculated to evaluate the environmental risk of microplastics in irrigation water, and the results revealed a high microplastic risk throughout the year except in November and January. This study provided a valuable reference and impetus for a better understanding of the microplastic profile and source apportionment in irrigation water, which was important for environmental management.

Microplastic accelerate the phosphorus-related metabolism of bacteria to promote the decomposition of methylphosphonate to methane

Microplastic (MP) contaminants in marine water have become a global public health concern because of their persistence and potentially adverse effects on organisms. MP can affect the growth and metabolism of marine microorganisms and further impact the microbial environmental functions. The molecular impact mechanisms of MP on specific functional microbes with the capability of decomposing methylphosphonate (MPn) to release methane (CH₄) in oxygenated water have rarely been reported upon. Herein, we investigated the effects of MP on microbes and concomitant methanogenesis via the microbial degradation of MPn. Furthermore, the specific perturbation was revealed at the molecular level combined with transcriptomics and metabolomics. The results showed that intracellular phosphorus utilization by MPn-degrading strain Burkholderia sp. HQL1813 was enhanced by accelerating the catabolism of MPn. Phosphorus transport-related genes (phnG-M, pstSCAB, phnCDE) were upregulated in the MP exposure groups. Amino acid metabolism, the phosphotransferase system and nucleotide metabolism were also perturbed after MP exposure. Notably, released CH₄ increased by 24 %, 29 % and 14 % in the exposure group. In addition, the responses of the strain were dose-independent with increasing MP doses. These findings are beneficial for clarifying the effect of MP on specific functional microbes at the molecular level and their degradation of CH₄ by MPn.

Abundance and distribution of microplastics in surface waters of the Kattegat/ Skagerrak (Denmark)

Microplastics (MPs) are ubiquitous pollutants in the ocean, and there is a general concern about their persistence and potential effects on marine ecosystems. We still know little about the smaller size-fraction of marine MPs (MPs <300 μm), which are not collected with standard nets for MPs monitoring (e.g., Manta net). This study aims to determine the concentration, composition, and size distribution of MPs down to 10 μm in the Kattegat/Skagerrak area. Surface water samples were collected at fourteen stations using a plastic-free pump-filter device (UFO sampler) in October 2020. The samples were treated with an enzymatic-oxidative method and analyzed using FPA-μFTIR imaging. MPs concentrations ranged between 11 and 87 MP m^-3, with 88% of the MPs being smaller than 300 μm. The most abundant shape of MPs were fragments (56%), and polyester, polypropylene, and polyethylene were the dominant synthetic polymer types. The concentration of MPs shows a significant positive correlation to the seawater density. Furthermore, there was a tendency towards higher MPs concentrations in the Northern and the Southern parts of the study area. The concentration of MPs collected with the UFO sampler was several orders of magnitude higher than those commonly found in samples collected with the Manta net due to the dominance of MP smaller size fractions. Despite the multiple potential sources of MPs in the study area, the level of MPs pollution in the surface waters was low compared (<100 MP m^-3) to other regions. The concentrations of MPs found in the studied surface waters were six orders of magnitude lower than those causing negative effects on pelagic organisms based on laboratory exposure studies, thus is not expected to cause any impact on the pelagic food web.

Plastic photodegradation under simulated marine conditions

Ocean plastic pollution is a problem of increasing magnitude; yet, the amount of plastic at the sea surface is much lower than expected. Solar ultraviolet (UV) radiation can induce photodegradation, but its importance in determining the longevity of floating plastic remains unconstrained. Here, we measured photodegradation rates of different plastic types slightly larger than microplastics (virgin polymers and floating plastic debris) under simulated marine conditions. UV irradiation caused all plastic types to leach dissolved organic carbon, and to a lesser degree carbon dioxide, carbon monoxide, methane, and other hydrocarbon gases. The release of photodegradation products translates to degradation rates of 1.7-2.3 % yr^-1 of the tested plastic particles normalized to conditions as found in the subtropical surface ocean. Modelling the accumulation of floating plastic debris, our results show that solar UV radiation could already have degraded 7 to 22 % of all floating plastic that has ever been released to the sea.

Exposure to Polypropylene Microplastics via Oral Ingestion Induces Colonic Apoptosis and Intestinal Barrier Damage through Oxidative Stress and Inflammation in Mice

Extensive environmental pollution by microplastics has increased the risk of human exposure to plastics. However, the biosafety of polypropylene microplastics (PP-MPs), especially of PP particles < 10 μm, in mammals has not been studied. Thus, here, we explored the mechanism of action and effect of exposure to small and large PP-MPs, via oral ingestion, on the mouse intestinal tract. Male C57BL/6 mice were administered PP suspensions (8 and 70 μm; 0.1, 1.0, and 10 mg/mL) for 28 days. PP-MP treatment resulted in inflammatory pathological damage, ultrastructural changes in intestinal epithelial cells, imbalance of the redox system, and inflammatory reactions in the colon. Additionally, we observed damage to the tight junctions of the colon and decreased intestinal mucus secretion and ion transporter expression. Further, the apoptotic rate of colonic cells significantly increased after PP-MP treatment. The expression of pro-inflammatory and pro-apoptosis proteins significantly increased in colon tissue, while the expression of anti-inflammatory and anti-apoptosis proteins significantly decreased. In summary, this study demonstrates that PP-MPs induce colonic apoptosis and intestinal barrier damage through oxidative stress and activation of the TLR4/NF-κB inflammatory signal pathway in mice, which provides new insights into the toxicity of MPs in mammals.

Ancestral Sequence Reconstruction Identifies Structural Changes Underlying the Evolution of Ideonella sakaiensis PETase and Variants with Improved Stability and Activity

The improved production, recycling, and removal of plastic waste, such as polyethylene terephthalate (PET), are pressing environmental and economic issues for society. Biocatalytic (enzymatic) PET depolymerization is potentially a sustainable, low-energy solution to PET recycling, especially when compared with current disposal methods such as landfills, incineration, or gasification. IsPETase has been extensively studied for its use in PET depolymerization; however, its evolution from cutinases is not fully understood, and most engineering studies have neglected the majority of the available sequence space remote from the active site. In this study, ancestral protein reconstruction (ASR) has been used to trace the evolutionary trajectory from ancient serine hydrolases to IsPETase, while ASR and the related design approach, protein repair one-stop shop, were used to identify enzyme variants with improved activity and stability. Kinetic and structural characterization of these variants reveals new insights into the evolution of PETase activity and the role of second-shell mutations around the active site. Among the designed and reconstructed variants, we identified several with melting points 20 °C higher than that of IsPETase and two variants with significantly higher catalytic activity.

Investigating the evolution of the technologies for collecting microplastics

To stop the dispersion of microplastics in the ecosystem, many technologies for collecting them were designed, tested and developed in the last period. However, a complete and exhaustive comparison of these technologies to guide in the choice and/or in the development of the most suitable appropriate one is missing in the literature. This study investigates the presence of some known technological trends, deriving from the TRIZ (Russian acronym for "Theory of Inventive Problem Solving") in the behaviour (i.e. the operating principle) of these technologies. To do this, a systematic methodology was followed, which has a general value and consists in analysing the patents relating to these technologies through various bibliometric indexes (i.e. Innovation index, Emergence Score index, Independent Claims index and Technology Cycle Time index). In general, the obtained results did not reveal a clearly identifiable ranking of the behaviour which was unanimously confirmed by all the considered bibliometric indexes. In addition, the average of the scores of the different indexes associated with the different behaviours equalized their differences. However, these results are mainly due to the markedly different evaluations obtained by the Emergence Score index compared to those of the other indexes. From the comparison of the results with the evolutionary trends, it emerged that the operative zone reduction trend was the most confirmed, while the technical system dematerialization was the least confirmed by the bibliometric analysis of all the indexes. In particular, the ranking of the behaviours provided by the Innovation index best confirmed all the evolutionary trends, while that of the Emergence Score index was the worst. In conclusion, this study confirmed the adherence of the development that technologies for collecting microplastics are following to the evolutionary trends through bibliometric analysis: this sequence places magnetic technologies in first place, followed by chemical, fluid dynamics, dynamic mechanics and static mechanics. The analysis of the performances declared in the patents substantially confirms this result.

Effects of environmental and anthropogenic factors on the distribution and abundance of microplastics in freshwater ecosystems

Although microplastics are emerging marine pollutants that have recently attracted increasing attention, it is still difficult to identify their sources. This study reviewed 6487 articles to determine current research trends and found 237 effective concentration points after sorting, which were distributed in four regions and related to freshwater ecosystems. Results found that 15 environmental variables represented natural and anthropogenic environmental characteristics, of which seven environmental variables were selected for experimental modelling. Random forest models fitted sample data, thus facilitating the identification of regional microplastics distribution. The global random forest model had random forest importance scores (RFISs) for gross domestic product, population, and the proportion of agricultural land use were 15.76 %, 15.64 %, and 14.74 %, respectively; these indicate that human activities significantly affected the global distribution of microplastics. In Asia, agriculture and urban activities are the main sources of microplastics, with an RFIS of 11.58 % and 12.24 % for the proportion of agricultural and urban land use, respectively. Activities in urban areas were determined to be the main influencing factors in North America, with an RFIS of 13.92 % for the proportion of urban land use. Agricultural activities were the main influencing factors in Europe, with RFISs for the proportion of agricultural land use of 16.90 %. Our results indicate that region-specific policies are required to control microplastics in different regions, with soil composition being a latency factor that affects microplastics' distribution.

New Methods for the Quantification of Ingested Nano- and Ultrafine Plastics in Seabirds

Plastic ingestion has been documented in a plethora of taxa. However, there is a significant gap in the detection of nano- and ultrafine particles due to size limitations of commonly used techniques. Using two Australian seabird species as case studies, the flesh-footed shearwater (FFSH) Ardenna carneipes and short-tailed shearwater (STSH) A. tenuirostris, we tested a novel approach of flow cytometry to quantify ingested particles <70 μm in the fecal precursor (guano; colon and cloacal contents) of both species. This method provided the first baseline data set for these species for plastics in the 200 nm-70 μm particle size ranges and detected a mean of 553.50 ± 91.21 and 350.70 ± 52.08 plastics (count/mg fecal precursor, wet mass) in STSH and FFSH, respectively, whereas Fourier transform infrared spectroscopy (FT-IR) provided accurate measurements of polymer compositions and quantities in the size range above 5.5 × 5.5 μm². The abundance of nano- and ultrafine particles in the guano (count/mg) was not significantly different between species (p-value = 0.051), suggesting that foraging distribution or prey items, but not species, may contribute to the consumption of small plastics. In addition, there was no correlation between macroplastics in the stomach compared to the fecal precursor, indicating that small particles are likely bioaccumulating (e.g., through shedding and digestive fragmentation) and/or being directly ingested. Combining flow cytometry with FT-IR provides a powerful quantitative and qualitative analysis tool for detecting particles orders of magnitude smaller than that are currently explored with wider applications across taxa and marine environments.

Review of research on migration, distribution, biological effects, and analytical methods of microfibers in the environment

Microplastics have been proven to be one of the critical environmental pollution issues. Moreover, microfibers, the most prominent form of microplastics in the environment, have likewise attracted the attention of various countries. With the increase in global population and industrialization, the production and use of fibers continue to increase yearly. As a result, a large number of microfibers are formed. If fiber products are not used or handled correctly, it will cause direct/indirect severe microfiber environmental pollution. Microfibers will be further broken into smaller fiber fragments when they enter the natural environment. Presently, researchers have conducted extensive research in the identification of microfibers, laying the foundation for further resourcefulness research. This work used bibliometric analysis to review the microfiber contamination researches systematically. First, the primary sources of microfibers and the influencing factors are analyzed. We aim to summarize the influence of the clothing fiber preparation and care processes on microfiber formation. Then, this work elaborated on the migration in/between water, atmosphere, and terrestrial environments. We also discussed the effects of microfiber on ecosystems. Finally, microfibers' current and foreseeable effective treatment, disposal, and resource utilization methods were explained. This paper will provide a structured reference for future microfiber research.

Quantification of ternary microplastic mixtures through an ultra-compact near-infrared spectrometer coupled with chemometric tools

The ubiquitous distribution of plastics and microplastics (MPs) and their resistance to biological and chemical decay is adversely affecting the environment. MPs are considered as emerging contaminants of concern in all the compartments, including terrestrial, aquatic, and atmospheric environments. Efficient monitoring, detection, and removal technologies require reliable methods for a qualitative and quantitative analysis of MPs, considering point-of-need testing a new evolution and a great trend at the market level. In the last years, portable spectrometers have gained popularity thanks to the excellent capability for fast and on-site measurements. Ultra-compact spectrometers coupled with chemometric tools have shown great potential in the polymer analysis, showing promising applications in the environmental field. Nevertheless, systematic studies are still required, in particular for the identification and quantification of fragments at the microscale. This study demonstrates the proof-of-concept of a Miniaturized Near-Infrared (MicroNIR) spectrometer coupled with chemometrics for the quantitative analysis of ternary mixtures of MPs. Polymers were chosen representing the three most common polymers found in the environment (polypropylene, polyethene, and polystyrene). Daily used plastic items were mechanically fragmented at laboratory scale mimicking the environmental breakdown process and creating "true-to-life" MPs for the assessment of analytical methods for MPs identification and quantification. The chemical nature of samples before and after fragmentation was checked by Raman spectroscopy. Sixty three different mixtures were prepared: 42 for the training set and 21 for the test set. Blends were investigated by the MicroNIR spectrometer, and the dataset was analysed using Principal Component Analysis (PCA) and Partial Least Square (PLS) Regression. PCA score plot showed a samples distribution consistent with their composition. Quantitative analysis by PLS showed the great capability prediction of the polymer's percentage in the mixtures, with R² greater than 0.9 for the three analytes and a low and comparable Root-Mean Square Error. In addition, the developed model was challenged with environmental weathered materials to validate the system with real plastic pollution. The findings show the feasibility of employing a portable tool in conjunction with chemometrics to quantify the most abundant forms of MPs found in the environment.

Microplastic contamination in seawater across global marine protected areas boundaries

Despite the relatively rich literature on the omnipresence of microplastics in marine environments, the current status and ecological impacts of microplastics on global Marine Protected Areas (MPAs) are still unknown. Their ubiquitous occurrence, increasing volume, and ecotoxicological effects have made microplastic an emerging marine pollutant. Given the critical conservation roles of MPAs that aim to protect vulnerable marine species, biodiversity, and resources, it is essential to have a comprehensive overview of the occurrence, abundance, distribution, and characteristics of microplastics in MPAs including their buffer zones. Here, extensive data were collected and screened based on 1565 peer-reviewed literature from 2017 to 2020, and a GIS-based approach was applied to improve the outcomes by considering boundary limits. Microplastics in seawater samples were verified within the boundaries of 52 MPAs; after including the buffer zones, 1/3 more (68 MPAs) were identified as contaminated by microplastics. A large range of microplastic levels in MPAs was summarized based on water volume (0-809,000 items/m³) or surface water area (21.3-1,650,000,000 items/km²), which was likely due to discrepancy in sampling and analytical methods. Fragment was the most frequently observed shape and fiber was the most abundant shape. PE and PP were the most common and also most abundant polymer types. Overall, 2/3 of available data reported that seawater microplastic levels in MPAs were higher than 12,429 items/km², indicating that global MPAs alone cannot protect against microplastic pollution. The current limitations and future directions were also discussed toward the post-2020 Global Biodiversity Framework goals.

A stable isotope assay with 13C-labeled polyethylene to investigate plastic mineralization mediated by Rhodococcus ruber

Methods that unambiguously prove microbial plastic degradation and allow for quantification of degradation rates are necessary to constrain the influence of microbial degradation on the marine plastic budget. We developed an assay based on stable isotope tracer techniques to determine microbial plastic mineralization rates in liquid medium on a lab scale. For the experiments, ¹³C-labeled polyethylene (¹³C-PE) particles (irradiated with UV-light to mimic exposure of floating plastic to sunlight) were incubated in liquid medium with Rhodococcus ruber as a model organism for proof of principle. The transfer of ¹³C from ¹³C-PE into the gaseous and dissolved CO₂ pools translated to microbially mediated mineralization rates of up to 1.2 % yr^-1 of the added PE. After incubation, we also found highly ¹³C-enriched membrane fatty acids of R. ruber including compounds involved in cellular stress responses. We demonstrated that isotope tracer techniques are a valuable tool to detect and quantify microbial plastic degradation.

Interactions of microplastics and soil pollutants in soil-plant systems

In recent years, increasing studies have been reported on characterization and detection of microplastics (MPs), and their interactions with organic pollutants (OPs) and heavy metals (HMs) in soils. However, a comprehensive review on the characteristics and factors that influence MPs distribution in soils, the sorption characteristics and mechanisms of soil contaminants by MPs, especially the interactions of MPs and their complexes with pollutants in the soil-plant systems remains rarely available at present. This review focuses on the sorption features and mechanisms of pollutants by MPs in soil and discussed the effects of MPs and their complexing with pollutants on soil properties, microbe and plants. The polarity of MPs significantly influenced the sorption of OPs, and different sorption mechanisms are involved for the hydrophobic and hydrophilic OPs. The sorption of OPs on MPs in soils is different from that in water. Aging of MPs can promote the sorption and migration of contaminants. The enhanced effects of biofilm in microplastisphere on the sorption of pollutants by MPs are critical, and interactions of soil environment-MPs-microbe-HMs-antibiotics increase the potential pathogens and larger release of resistance genes. The coexistence of HMs and MPs affected the growth of plants and the uptake of HMs and MPs by the plants. Moreover, the type, dose, shape and particle size of MPs have important influences on their interactions with pollutants and subsequent effects on soil properties, microbial activities and plant growth. This review also pointed out some knowledge gaps and constructive countermeasures to promote future research in this field.

Comparison between the traditional Manta net and an innovative device for microplastic sampling in surface marine waters

Manta nets are commonly used for microplastics sampling although a number of limitations have emerged. In this study we compare the manta net to an innovative microplastic sampler, referred to as MuMi, registered as utility model. The results highlight the large variability that can exist in the outcomes of the different studies due to the lack of harmonization between methods and the differing factors such as sampling mesh size, representativeness or reproducibility of the sampling volumes. Control over the filtered volume is an issue to be improved in trawl sampling methods, while in the MuMi sampler the control over the sampling depth could be improved. Still, MuMi represents a highly advantageous sampling system in terms of ease of operation, lower cost, smaller microplastics target size and greater precision, all while maintaining the representativeness of the collected samples.

Detection and characterisation of microplastics and microfibres in fishmeal and soybean meal

Aquaculture is an increasingly important source of nutrition for global food security, which is reliant on animal- and plant-based feeds. Anthropogenic particles, including microplastics and semi-synthetic cellulosic fibres, are prolific marine pollutants that are readily consumed by marine organisms, including small pelagic fish commonly used in fishmeal. Conversely, there is no indication plants can accumulate anthropogenic microparticles. We explore whether aquaculture feed presents a route of contamination for farmed fish. Commercially-sourced aquaculture feedstocks, including fishmeals and soybean meal, were processed (KOH digestion and ZnCl₂ density separation) and anthropogenic particles characterised using microscopy and spectroscopic methods. Both fishmeal and soybean meals contained anthropogenic particles, with concentrations ranging 1070-2000 particles kg^-1. The prevalence of anthropogenic particles in plant-based feeds indicates that the majority of contamination occurs post-harvest. Based on our findings, farmed Atlantic salmon may be exposed to a minimum of 1788-3013 anthropogenic particles from aquaculture feed across their commercial lifespan.

Evidence of microplastic-mediated transfer of PCB-153 to sea urchin tissues using radiotracers

The present study reports the first experimental microplastic-mediated transfer of a key PCB congener into adult specimens of the sea urchin Paracentrotus lividus. Three experiments were conducted to assess whether ¹⁴C-PCB-153 adsorbed onto negatively buoyant microplastics (MPs) (500-600 μm) is bioavailable to the sea urchin: (1) exposure to a low concentration of ¹⁴C-PCB-153 sorbed onto a high number of virgin MPs ("lowPCB highMP" experiment), (2) exposure to a high concentration of ¹⁴C-PCB-153 sorbed onto a relatively low number of virgin MPs ("highPCB lowMP" experiment), and (3) exposure to a low concentration of ¹⁴C-PCB-153 sorbed onto a relatively low number of aged MP ("lowPCB lowMP" experiment). Results showed that the transfer of ¹⁴C-PCB-153 from MPs to sea urchin tissues occurred in each of the three 15-day experiments, suggesting that MPs located on the seafloor may act as vectors of PCB-153 to sea urchins even during short-term exposure events.

Microplastic pollution in the surface waters of Vava'u, Tonga

Marine plastic pollution, particularly microplastics, has been recognised as a global issue in the recent years, but research efforts in the Pacific are lagging. We carried out research on microplastics contamination of surface waters of the Vava'u archipelago, Tonga. Since microplastics smaller than the standard mesh size (333-335 μm) are readily reported in the literature on microplastics, we used a finer plankton net (100 μm) to determine the proportion of captured microplastics smaller than 300 μm. Isolated microplastics were counted and measured using stereomicroscope with polymer identification performed by FTIR spectroscopy. The analysis revealed high microplastics concentrations (329,299.7 ± 40,994.2 pcs km^-2 or 1.05 ± 0.13 pcs m^-3). The proportion of particles smaller than 300 μm was 40 %. The predominant type of microplastics in surface waters were small bits of white film, which we associated with cement-filled white bags used to construct docks throughout Vava'u, often heavily eroded.

Microplastics in atmospheric dust samples of Sistan: sources and distribution

In this work, the amount and physical and chemical characteristics of airborne microplastics (MPs) pollution in dust samples in Sistan, located in the eastern part of Iran, is reported. Sampling stations were selected according to the wind direction and population density. MPs were collected by a static dust sampler and analyzed by optical microscopy and FT-IR spectroscopy. Results showed that the distribution frequency of MPs in residential and non-residential areas was 6 to 11 pieces per 100 g (pcs/100 g) with an average abundance of 9.8 pcs/100 g. Fragmented MPs were approximately consisted 64% of total MPs and their sizes were in the range of 0.9-3.8 mm. Polyethylene (49%), polystyrene (21%) and polyester (18%) were the main MPs presented in the dust samples. It was observed that population density and wind direction were the most important parameters affecting MPs pollution in dust.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40201-022-00833-y.

Extraction and quantification of polystyrene nanoplastics from biological samples

Accurate quantification of nanoplastics (NPs) in complex matrices remains a challenge, especially for biological samples containing high content of organic matters. Herein, a new method extracting and quantifying polystyrene (PS) NPs from biological samples was developed. The extraction included alkaline digestion, centrifugation, and cloud point extraction (CPE), and the quantification included gold nanoparticles formation and labeling on surfaces of the extracted NPs and thereafter measurement with single particle inductively coupled plasma mass spectrometry (SP-ICP-MS). Results show that 25% tetramethylammonium hydroxide solution was an effective alkaline digestion solution for biological matrices, and CPE after centrifugation (3000 rpm, 10 min) was applicable to purify and enrich PS NPs with different sizes (100 and 500 nm) and surface functionalities (-COOH and -NH₂ modifications) from the digestion solution. The efficiency of Au labeling on PS NPs surface was improved by about 70% in the presence of 100 μM cetyltrimethylammonium bromide. The performance of the quantification method was examined by extraction and measurement of PS NPs spiked in four representative organism samples including bacteria, algae, nematode, and earthworm, and was further validated by analyzing the accumulated PS NPs in exposed nematodes. Good recovery rates (65 ± 10%-122 ± 22%) were achieved for spiking levels of 5-50 μg g^-1; the limit of detection was 3.7 × 10⁷ particles g^-1, corresponding to the mass concentration of about 0.02 and 2.5 μg g^-1 for the 100 nm and 500 nm PS NPs, respectively. The established extraction and quantification methods are efficient and sensitive, providing a useful approach for further exploring the environmental behavior and toxicity of NPs.

Detection of Environmental Microfiber Pollutants through Vibrational Spectroscopic Techniques: Recent Advances of Environmental Monitoring and Future Prospects

A robust environmental monitoring system is highly essential for the instant detection of environmental microfiber pollutants for the sustainable management of the environment and human health. The extent of microfiber pollution is growing exponentially across the globe in both terrestrial and marine environments. An immediate and accurate environmental monitoring system is crucial to investigate the composition and distribution of these micropollutants. Fourier Transform Infrared Spectroscopy and Raman Spectroscopy are vibrational spectroscopic techniques that have the novel ability to detect microfibers within a minute concentration from diverse environmental samples. The major micropollutants which have been analyzed are polyethylene, polypropylene, nylon 6, polystyrene, and polyethylene terephthalate. After a detailed and critical study of the various aspects of spectroscopic analysis, the review is concluded with a comprehensive discussion of the significance of these robust methods and their application in future aspects for further preventing microfiber pollution in the marine environment. This study highlights the utilities and significance of vibrational spectroscopic detection techniques for the immediate and accurate identification of synthetic microfibers. This review also evaluated the implementation of spectroscopic methods as a precise tool for the characterization and monitoring of microfiber pollutants in the environment.

Nanoplastics and ultrafine microplastic in the Dutch Wadden Sea - The hidden plastics debris?

Plastic pollution in the marine environment has been identified as a global problem; different polymer types and fragment sizes have been detected across all marine regions, from sea ice to the equator and the surface to the deep sea. However, quantification of marine plastics debris in the size range of nanoplastics (<1 μm) and ultrafine microplastics (<10 μm) is not constrained, because such minuscule particles are challenging to measure. In this work, we applied a novel analytical assay using Thermal Desorption - Proton Transfer Reaction - Mass Spectrometry (TD-PTR-MS), which is suitable to detect and identify plastics in the nanogram range. From two stations in the Wadden Sea (the Netherlands), we measured nanoplastics directly from seawater aliquots, and from filters with different mesh sizes. Our results show the presence of Polystyrene (PS) and Polyethylene terephthalate (PET) nanopalstics as well as ultrafine microplastics in the Wadden Sea water column. The mass concentration of PS nanoplastics was 4.2 μg/L on average, indicating a substantial contribution of nanoplastics to the Wadden Sea's total plastic budget.

How small is the big problem? Small microplastics <300 μm abundant in marine surface waters of the Great Barrier Reef Marine Park

Particle size plays an important role in determining the behaviour, fate and effects of microplastics (MPs), yet little is known about MPs <300 μm in aquatic environments. Therefore, we performed the first assessment of MPs in marine surface waters around the Whitsunday Islands region of the Great Barrier Reef Marine Park, Australia, to test for the presence of small MPs (50-300 μm) in-situ. Using a modified manta net, we demonstrate that MPs were present in all marine surface water samples, with a mean sea surface concentration of 0.23 ± 0.03 particles m^-3. Microplastics were mainly blue, clear and black fibres and fragments, consisting of polyethylene terephthalate, high-density polyethylene and polypropylene plastic polymers. Tourism and marine recreation were considered the major contributing sources of MPs to surface waters around the Whitsunday Islands. Between 10 and 124 times the number of MPs exist in the 50 μm-300 μm size class, compared with the 1 mm-5 mm size range. This finding indicates that the global abundance of small MPs in marine surface waters is grossly underestimated and warrants further investigation. Research into the occurrence, characteristics and environmental fate of MPs <300 μm is needed to improve our understanding of the cumulative threats facing valuable ecosystems due to this smaller, potentially more hazardous size class.

Algae: a frontline photosynthetic organism in the microplastic catastrophe

Recalcitrancy in microplastics (MPs) contributes to white pollution. Bioremediation can remove MPs and facilitate environmental sustainability. Although recent studies have been conducted on the interaction of algae and MPs, the role of algae in MP removal with the simultaneous implementation of 'omics studies has not yet been discussed. Here, we review the adverse effects of MPs on the environment and possible approaches to remove them from the aquatic environment by using algae. We highlight the mechanism of MP biodegradation, the algal species that have been used, and how these are affected by MPs. We propose that algomics, characterization of biodegrading enzymes, and genetic engineering could be effective strategies for optimizing MP degradation.

Toward a long-term monitoring program for seawater plastic pollution in the north Pacific Ocean: Review and global comparison

Through a literature survey and meta-data analysis, monitoring methods and contamination levels of marine micro- and macroplastics in seawater were compared between the North Pacific and the world's other ocean basins. The minimum cut-off size in sampling and/or analysis of microplastics was crucial to the comparison of monitoring data. The North Pacific was most actively monitored for microplastics and showed comparatively high levels in the global context, while the Mediterranean Sea was most frequently monitored for macroplastics. Of the 65 extracted mean abundances of microplastics in seawater from the North Pacific, two (3.1%) exceeded the lowest predicted no-effect concentration (PNEC) proposed thus far. However, in the context of business-as-usual conditions, the PNEC exceedance probability may be expected to reach 27.7% in the North Pacific in 2100. The abundance of marine plastics in seawater, which reflects the current pollution status and marine organisms' waterborne exposure levels, is a useful indicator for marine plastic pollution. For regional and global assessments of pollution status across space and time, as well as assessment of ecological risk, two microplastic monitoring approaches are recommended along with their key aspects. Although microplastic pollution is closely linked with macroplastics, the monitoring data available for floating macroplastics and more extent to mesoplastics in most ocean basins are limited. A more specific framework for visual macroplastic survey (e.g. fixed minimum cut-off size, along with survey transect width and length according to survey vessel class) is required to facilitate data comparison. With the implementation of standardised methods, increased efforts are required to gather monitoring data for microplastics and-more importantly-floating macroplastics in seawater worldwide.

Assessment of manta trawling and two newly-developed surface water microplastic monitoring techniques in the open sea

The ubiquitous microplastic (MP) pollution across the waterways, sediments, biota, and atmosphere has amplified concerns at a global scale. Unfortunately, harmonized MP monitoring protocols are absent for accurate evaluation on MP pollution. Few large-scale MP sampling programs involving different designs have been implemented in the open sea. In this study, a manta trawling and two newly custom-built pump filtration systems, namely, a trawl-underway pump combination system coupled in conjunction with an in-situ filtration device (Y-shaped filter, New Type I) and a stationary onboard pumping coupled to Y-shaped filter (New Type II), were evaluated for MP pollution in the mid-North Pacific Ocean. The trawling-based systems (manta trawl and New Type I) collected samples covering a large area, whereas New Type II operated at a fixed site. The new systems achieved fractionated filtration of MPs on site and prevented airborne contamination. The electronic fuel meter installed in the New Type II yielded a more accurate volume. Results showed that the average MP abundance of the aforementioned sampling techniques were 0.65, 2.56, and 7.48 items m^-3, respectively. The abundances in the same particle size range (0.3-5.0 mm) from the new systems were higher. The recovered MPs from all systems were mainly white and polypropylene. Note that the MPs from the manta trawl were primarily fragments; however, they were mainly fibers from the new systems. This corroborated the capability of new systems in harvesting small items (0.1-0.3 mm) and fibers. The cost analysis showed that the new systems beat the manta trawl concerning price performance. The study results provide alternatives for future MP sampling, which will ultimately aid in the method harmonization and standardization of MP sampling.

Variance and precision of microplastic sampling in urban rivers

Microplastics (MPs), plastic particles <5 mm in diameter, have become an emerging ubiquitous concern for the environment. Rivers are the primary pathways that transport MPs from the land to the ocean; however, standardized methodologies for in-situ sampling in freshwater environments remain undefined. Notably, uncertainties in MP sampling methods lead to errors in estimating MP discharge through rivers. In the present study, the inter-sample variance of plankton net-obtained MP concentrations for two urban rivers in Japan was investigated. Numerical concentrations, expressed in particles·m^-3, revealed that variance s² was proportional to the mean m of replicated estimates of numerical concentrations. A derived statistical model suggested that river MPs disperse according to purely random processes; that is, Poisson point processes. Accordingly, a method was established to project the "precision," the ratio of the standard error to m, of numerical concentrations based on the number of net sampling repetitions. It was found that the mean of two replicates maintained sufficient precision of <30% for conditions with high concentrations of ≥3 particles·m^-3. Projected precisions under different levels of MP concentrations are also presented to help design future field campaigns.

Review on invasion of microplastic in our ecosystem and implications

Today the world is going through the "Plastic Age." Nowadays, it is difficult to find a commonly used convenient item that is nonplastic. Plastic production and consumption, thus, increased exponentially and plastic emerged as one of the major concerns for waste management. Recent studies confirmed a faster rate of plastic degradation than previously believed under various conditions (e.g. saltwater, UV, soil interaction) that microplastic has become a new type of health-hazardous pollution source. Much research has been conducted since the discovery of the "Pacific Garbage Patch," and the scope has expanded from marine to soil, groundwater, air, and food chain. This article underwent a substantial amount of literature review to verify the degree of microplastic pollution progression in major pillars of the environment (aqueous, terrestrial, airborne, bio-organism, and human). Multiple kinds of literature indicated a high possibility of vigorous interaction among the pillars that microplastic is not stationary at the point of contamination but travels across the nation (transboundary) and medium (transmedium). Thus, only the waste reduction policy (i.e. production and consumption reduction) would be effective through a single national or local effort, while pollution and contamination management require more of a collective, if not global, approach. For these characteristics, this article proposes two most urgently required actions to combat microplastic pollution: (a) global acknowledgement of microplastic as transboundary and transmedium pollution source that require international collective action and (b) standardization of microplastic related research including basic definition and experimental specification to secure global comparativeness among data analysis. Without resolving these two issues, it could be very difficult to obtain an accurate global status mapping of microplastic pollution to design effective and efficient global microplastic pollution management policies.

First assessment of microplastic and artificial microfiber contamination in surface waters of the Amazon Continental Shelf

The composition and distribution of microplastics (MPs) in the Brazilian Amazon Continental Shelf surface waters are described for the first time. The study was conducted during the 2018 rainy and dry seasons, using 57 water samples collected with aluminum buckets and filtered through a 64-μm mesh. The samples were vacuum-filtered in a still-air box, and the content of each filter was measured, counted, and classified. A total of 12,288 floating MPs were retrieved; particles were present at all 57 sampling points. The mean MP abundance was 3593 ± 2264 items·m^-3, with significantly higher values during the rainy season (1500 to 12,967; 4772 ± 2761 items·m^-3) than in the dry season (323 to 5733; 2672 ± 1167 items·m^-3). Polyamides (PA), polyurethane (PU), and acrylonitrile butadiene styrene (ABS) were the most common polymers identified through Fourier Transform Infrared Spectroscopy (FTIR) analysis. Cellulose-based textile fibers were also abundant (~40%). Our results indicate that the Amazon Continental Shelf is contaminated with moderate to high levels of MPs; the highest abundances were recorded at stations near land-based sources such as river mouths and large coastal cities.

Blueprint for the ideal microplastic effect study: Critical issues of current experimental approaches and envisioning a path forward

This article presents a novel conceptual blueprint for an 'ideal', i.e., ecologically relevant, microplastic effect study. The blueprint considers how microplastics should be characterized and applied in laboratory experiments, and how biological responses should be measured to assure unbiased data that reliably reflect the effects of microplastics on aquatic biota. This 'ideal' experiment, although practically unachievable, serves as a backdrop to improve specific aspects of experimental research on microplastic effects. In addition, a systematic and quantitative literature review identified and quantified departures of published experiments from the proposed 'ideal' design. These departures are related mainly to the experimental design of microplastic effect studies failing to mimic natural environments, and experiments with limited potential to be scaled-up to ecosystem level. To produce a valid and generalizable assessment of the effect of microplastics on biota, a quantitative meta-analysis was performed that incorporated the departure of studies from the 'ideal' experiment (a measure of experimental quality) and inverse variance (a measure of the study precision) as weighting coefficients. Greater weights were assigned to experiments with higher quality and/or with lower variance in the response variables. This double-weighting captures jointly the technical quality, ecological relevance and precision of estimates provided in each study. The blueprint and associated meta-analysis provide an improved baseline for the design of ecologically relevant and technically sound experiments to understand the effects of microplastics on single species, populations and, ultimately, entire ecosystems.

Microbial communities on plastic particles in surface waters differ from subsurface waters of the North Pacific Subtropical Gyre

The long-term fate of plastics in the ocean and their interactions with marine microorganisms remain poorly understood. In particular, the role of sinking plastic particles as a transport vector for surface microbes towards the deep sea has not been investigated. Here, we present the first data on the composition of microbial communities on floating and suspended plastic particles recovered from the surface to the bathypelagic water column (0-2000 m water depth) of the North Pacific Subtropical Gyre. Microbial community composition of suspended plastic particles differed from that of plastic particles afloat at the sea surface. However, in both compartments, a diversity of hydrocarbon-degrading bacteria was identified. These findings indicate that microbial community members initially present on floating plastics are quickly replaced by microorganisms acquired from deeper water layers, thus suggesting a limited efficiency of sinking plastic particles to vertically transport microorganisms in the North Pacific Subtropical Gyre.

Uptake of microplastics by the snakelocks anemone (Anemonia viridis) is commonplace across environmental conditions

Microplastics (<1 mm) are ubiquitous in our oceans and widely acknowledged as concerning contaminants due to the multi-faceted threats they exert on marine organisms and ecosystems. Anthozoans, including sea anemones and corals, are particularly at risk of microplastic uptake due to their proximity to the coastline, non-selective feeding mechanisms and sedentary nature. Here, the common snakelocks anemone (Anemonia viridis) was used to generate understanding of microplastic uptake in the relatively understudied Anthozoa class. A series of microplastic exposure and multi-stressor experiments were performed to examine particle shape and size selectivity, and to test for the influence of food availability and temperature on microplastic uptake. All A. viridis individuals were found to readily take up microplastics (mean 142.1 ± 83.4 particles per gram of tissue) but exhibited limited preference between different particle shapes and sizes (n = 32). Closer examination identified that uptake involved both ingestion and external tissue adhesion, where microplastics were trapped in secreted mucus. Microplastic uptake in A. viridis was not influenced by the presence of food or elevated water temperature (n = 40). Furthermore, environmental sampling was performed to investigate microplastic uptake in A. viridis (n = 8) on the coast of southwest England, with a mean of 17.5 ± 4.0 particles taken up per individual. Fibres represented the majority of particles (91%) followed by fragments (9%), with 87% either clear, blue or black in colour. FTIR analysis identified 70% of the particles as anthropogenic cellulosic or plastic polymers. Thus, this study provides evidence of microplastic uptake by A. viridis in both laboratory exposures experiments and in the marine environment. These findings support recent literature suggesting that external adhesion may be the primary mechanism in which anthozoans capture microplastics from the water column and highlights the potential role anemones can play as environmental microplastic bioindicators.

Acrylic fabrics as a source of microplastics from portable washer and dryer: Impact of washing and drying parameters

Increasing uses of synthetic textiles are now a concerning issue as these synthetic textiles are shedding microfibers during the laundering of the fabrics and are considered as a potential source of microplastics (size <5 mm). In addition, manmade fibers like polyester, acrylic, and nylon represent 60% of the worldwide consumption of textile fibers. The novelty of this study is to assess the releasing trends of microfibers from acrylic fabrics during washing and drying under different conditions from a portable washer and dryer machine. Washing and drying effluents were filtered out which were further quantified with gravimetric analysis to determine the net weight of the released microfibers. Among different washing parameters, the mean length and diameter of the released microfibers were found to be approximately 2411 ± 1500 μm and 18 ± 4 μm, respectively. The results indicate that the release of microfibers increased by 2 and 1.4 times respectively when washing and drying time increased from 30 min to 60 min due to high mechanical stresses and longer rotational forces on the fabrics. The use of detergent during washing also promoted more microfiber release (162.49 ± 44.21 mg/kg) when compared to without detergent (60.22 ± 13.32 mg/kg). Moreover, microfibers were released approximately 1.8 times higher from washing when washed with 40 °C of water than with 20 °C of water. However, subsequent washing and drying cycles showed decreasing patterns of microfiber release as microfiber released 45% and 67% less during the 7th washing and drying cycle, respectively, compared to the 1st cycle. Results of this study would help to understand the releasing patterns of microfibers which can help to improve the existing systems to reduce the microplastic emissions from laundering.

Bisphenol A and microplastics weaken the antimicrobial ability of blood clams by disrupting humoral immune responses and suppressing hemocyte chemotactic activity

Robust antimicrobial capability is crucial for marine organisms survival in complex ocean environments. Although the detrimental impacts of emergent pollutants on cellular immune response of marine bivalve mollusks were increasingly documented, the effects of bisphenol A (BPA) and microplastics (MPs) on humoral immune response and hemocyte chemotactic activity remain unclear. Therefore, in this study, the toxicities of BPA and MPs, alone or in combination, to the antimicrobial ability, humoral immune response, and hemocyte chemotactic activity were investigated in the blood clam Tegillarca granosa. Our data demonstrated that exposure of blood clams to BPA, MPs, and BPA-MPs for 2 weeks lead to significant reductions in their survival rates upon pathogenic bacterial challenge, indicating evident impairment of antimicrobial ability. Compared to control, the plasma of pollutant-incubated blood clams exhibited significantly less antimicrobial activity against the growth of V. harveyi, suggesting significant reduction in humoral immune effectors including defensin, lysozyme (LZM), and lectin. Moreover, hemocytes migration across the polycarbonate membrane to the serum containing chamber was markedly arrested by 2-week exposure to BPA, MPs, and BPA-MPs, suggesting a hampered chemotactic activity. In addition, the intracellular contents of ROS and protein carbonyl in hemocytes were markedly induced whereas the expression levels of key genes from the MAPK and actin cytoskeleton regulation pathways were significantly suppressed upon exposure. In this study, it was also found that BPA-MP coexposure was significantly more toxic than single exposures. In summary, our findings revealed that exposure to the pollutants tested possibly impair the antimicrobial ability of blood clam through (1) reducing the inhibitory effect of plasma on bacterial growth, the contents of humoral immune effectors, and the chemotactic activity of hemocytes, (2) interrupting IL-17 activation of MAPK signal pathway, (3) inducing intracellular ROS, elevating protein carbonylation levels, and disrupting actin cytoskeleton regulation in hemocytes.

Polystyrene microplastics up-regulates liver glutamine and glutamate synthesis and promotes autophagy-dependent ferroptosis and apoptosis in the cerebellum through the liver-brain axis

Microplastics (MPs), which are emerging environmental pollutants, remain uncertainties in their toxic mechanism. MPs have been linked to severe liver metabolic disorders and neurotoxicity, but it is still unknown whether the abnormal metabolites induced by MPs can affect brain tissue through the liver-brain axis. Exposed to MPs of chickens results in liver metabolic disorders and increased glutamine and glutamate synthesis. The relative expression of glutamine in the C group was -0.862, the L-PS group was 0.271, and the H-PS group was 0.592. The expression of tight junction proteins in the blood-brain barrier (BBB) was reduced by PS-MPs. Occludin protein expression decreased by 35.8%-41.2%. Claudin 3 decreased by 19.6%-42.3%, and ZO-1 decreased by 28.3%-44.6%. Excessive glutamine and glutamate cooperated with PS-MPs to inhibit the Nrf2-Keap1-HO-1/NQO1 signaling pathway and triggered autophagy-dependent ferroptosis and apoptosis. GPX protein expression decreased by 30.9%-38%. LC3II/LC3I increased by 54%, and Caspase 3 increased by 45%. Eventually, the number of Purkinje cells was reduced, causing neurological dysfunction. In conclusion, this study provides new insights for revealing the mechanism of nervous system damaged caused by PS-MPs exposed in chickens.

Pelagic distribution of plastic debris (> 500 µm) and marine organisms in the upper layer of the North Atlantic Ocean

At present, the distribution of plastic debris in the ocean water column remains largely unknown. Such information, however, is required to assess the exposure of marine organisms to plastic pollution as well as to calculate the ocean plastic mass balance. Here, we provide water column profiles (0–300 m water depth) of plastic (0.05–5 cm in size) concentration and key planktonic species from the eastern North Atlantic Ocean. The amount of plastic decreases rapidly in the upper few meters, from ~ 1 item/m³ (~ 1000 µg/m³) at the sea surface to values of ~ 0.001–0.01 items/m³ (~ 0.1–10 µg/m³) at 300 m depth. Ratios of plastic to plankton varied between ~ 10^–5 and 1 plastic particles per individual with highest ratios typically found in the surface waters. We further observed that pelagic ratios were generally higher in the water column below the subtropical gyre compared to those in more coastal ecosystems. Lastly, we show plastic to (non-gelatinous) plankton ratios could be as high as ~ 10²–10⁷ plastic particles per individual when considering reported concentrations of small microplastics < 100 μm. Plastic pollution in our oceans may therefore soon exceed estimated safe concentrations for many pelagic species.

Pristine and artificially-aged polystyrene microplastic particles differ in regard to cellular response

Microplastic particles (MP), arising from the gradual decomposition of plastics in the environment, have been identified as a global problem. Most investigations of MP cytotoxicity use pristine spherical particles available from commercial sources when evaluating their impact on mammalian cells, while only limited data is available for the more relevant "weathered microplastic". In this study, we exposed murine macrophages to polystyrene MP either after up to 130 days of accelerated ageing or in pristine condition. Weathered and pristine MP were physicochemically characterized, and their cytotoxicity was investigated using biological assays, transcriptome analysis, and metabolic pathways prediction. Whereas the response to pristine MP is mainly dominated by a TNF-α release, sharp-edged weathered MP induce broader adverse cellular reactions. This study stresses the importance of including more realistic test particles (e.g., weathered particles) in combination with a broad range of biological assays when evaluating the potential risk of microplastic exposure.

Estimating global marine surface microplastic abundance: systematic literature review

Toxicity and persistence of microplastics (MP) in the marine environment has a potential to disturb the ecological balance of the planet. To evaluate the gravity of the situation, continuity in research of MP abundance is required. In this work for the first time a systematic literature review was conducted to build abundance datasets of MP at marine surface waters that were used to estimate average MP abundance and produce maps. Due to non-Gaussian distribution of the data, non-parametric statistics were used. The results show that an estimated average of approximately 6300 MP km^-2 MP float at the surface of the oceans. Additionally, observations of drawbacks in MP research that hamper inter-research comparability were made and these mainly include heterogeneity of methods and poor reporting practice. Basic guidelines to improve future research comparability were devised. Results provided here can be beneficial to research that requires a reliable and comparable MP abundance datasets sourced in a transparent and rigorous manner. These datasets are made available to the readers.

A record of microplastic in the marine nearshore waters of South Georgia

The polar plastics research community have recommended the spatial coverage of microplastic investigations in Antarctica and the Southern Ocean be increased. Presented here is a baseline estimate of microplastics in the nearshore waters of South Georgia, the first in situ study of the north-east coast of the island. Our results show that the microplastic concentration in seawater at twelve stations in proximity to King Edward Point Research Station ranged from 1.75 ± 5.17 MP/L (mean ± SD), approximately one order of magnitude higher than similar studies of sea surface waters south of the Polar Front. Levels of microplastics in freshwater (sampled from Gull Lake) and precipitation (collected adjacent to the research station) were 2.67 ± 3.05 MP/L, and 4.67 ± 3.21 MP/L respectively. There was no significant difference in the microplastic concentration between seawater sites, and no significant bilateral relationship between concentration and distance from the research station outlets. We report an average concentration of 1.66 ± 3.00 MP/L in wastewater collected from the research station but overall, the counts of microplastics were too low to attach any statistical significance to the similarity in the microplastic assemblages of seawater and wastewater, or assemblages retrieved from penguin species in the region in other studies. Using a calculation described in contemporary literature we estimate the number of microfibres potentially being released from ships and stations annually in the region but acknowledge that further samples are needed to support the figures generated. More extensive research into microplastic distribution, characteristics, and transport in the region is recommended to fully compute the level of risk which this pollutant represents to the ecosystem health of this remote region.