Breeding seabirds as vectors of microplastics from sea to land: Evidence from colonies in Arctic Canada

Polystyrene microplastics disrupted physical barriers, microbiota composition and immune responses in the cecum of developmental Japanese quails

Microplastics, a new type of emerging pollutant, is ubiquitous in terrestrial and water environments. Microplastics have become a growing concern due to their impacts on the environment, animal, and human health. Birds also suffer from microplastics contamination. In this study, we examined the toxic effects of polystyrene microplastics (PS-MPs) exposure on physical barrier, microbial community, and immune function in the cecum of a model bird species-Japanese quail (Coturnix japonica). The one-week-old birds were fed on environmentally relevant concentrations of 20 µg/kg, 400 µg/kg, and 8 mg/kg PS-MPs in the diet for 5 weeks. The results showed that microplastics could cause microstructural damages characterized by lamina propria damage and epithelial cell vacuolation and ultrastructural injuries including microvilli breakage and disarrangement as well as mitochondrial vacuolation in the cecum of quails. In particular, blurry tight junctions, wider desmosomes spacing, and gene expression alteration indicated cecal tight junction malfunction. Moreover, mucous layer breakdown and mucin decrease indicated that chemical barrier was disturbed by PS-MPs. PS-MPs also changed cecal microbial diversity. In addition, structural deformation of cecal tonsils and increasing proinflammatory cytokines suggested cecal immune disorder and inflammation responses by PS-MPs exposure. Our results suggested that microplastics negatively affected digestive system and might pose great health risks to terrestrial birds.

Indigo-dyed cellulose fibers and synthetic polymers in surface-feeding seabird chick regurgitates from the Gulf of Alaska

We provide evidence of anthropogenic materials ingestion in seabirds from a remote oceanic area, using regurgitates obtained from black-legged kittiwake (Rissa tridactyla) chicks from Middleton Island (Gulf of Alaska, USA). By means of GPS tracking of breeding adults, we identified foraging grounds where anthropogenic materials were most likely ingested. They were mainly located within the continental shelf of the Gulf of Alaska and near the Alaskan coastline. Anthropogenic cellulose fibers showed a high prevalence (85 % occurrence), whereas synthetic polymers (in the micro- and mesoplastics dimensional range) were less frequent (20 %). Most fibers (60 %) were blue and we confirmed the presence of indigo-dyed cellulosic fibers, characteristic of denim fabrics. In terms of mass, contamination levels were 0.077 μg g-1 wet weight and 0.009 μg g-1 wet weight for anthropogenic microfibers and synthetic polymers, respectively. These results represent the only recent report of contamination by anthropogenic fibers in seabirds from the Gulf of Alaska.

Microplastic in an apex predator: evidence from Barn owl (Tyto alba) pellets in two sites with different levels of anthropization

Plastic pollution in terrestrial and freshwater environments and its accumulation along food chains has been poorly studied in birds. The Barn owl (Tyto alba) is an opportunistic and nocturnal apex predator feeding mostly on small mammals. In this note, we reported evidence of microplastics (MPs) contamination in Barn owl pellets collected, for the first time, in two sites with different levels of anthropization (low: natural landscape mosaic vs. high extensive croplands). The following polymers have been recorded: polyvinylchloride (PVC), polyethylene (PE), expanded polyester (EPS), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyester (PL), viscose, and starch-based biopolymer. We found significant higher MPs frequency in the most anthropized site. Our results suggest that pellet' analysis may represent a cost-effective method for monitoring MP contamination along food chains in terrestrial ecosystems.

Regurgitated skua pellets containing the remains of South Atlantic seabirds can be used as biomonitors of small buoyant plastics at sea

Using seabirds as bioindicators of marine plastic pollution requires an understanding of how the plastic retained in each species compares with that found in their environment. We show that brown skua Catharacta antarctica regurgitated pellets can be used to characterise plastics in four seabird taxa breeding in the central South Atlantic, even though skua pellets might underrepresent the smallest plastic items in their prey. Fregetta storm petrels ingested more thread-like plastics and white-faced storm petrels Pelagodroma marina more industrial pellets than broad-billed prions Pachyptila vittata and great shearwaters Ardenna gravis. Ingested plastic composition (type, colour and polymer) was similar to floating plastics in the region sampled with a 200 μm net, but storm petrels were better indicators of the size of plastics than prions and shearwaters. Given this information, plastics in skua pellets containing the remains of seabirds can be used to track long-term changes in floating marine plastics.

How do life history and behaviour influence plastic ingestion risk in Canadian freshwater and terrestrial birds?

Plastic ingestion presents many potential avenues of risk for wildlife. Understanding which species and environments are most exposed to plastic pollution is a critical first step in investigating the One Health implications of plastic exposure. The objectives of this study were the following: 1) Utilize necropsy as part of ongoing passive disease surveillance to investigate ingested mesoplastics in birds collected in Ontario and Nunavut, and examine the relationships between bird-level factors and ingested debris; 2) evaluate microplastic ingestion compared to ingested mesodebris in raptors; and 3) identify potential sentinel species for plastic pollution monitoring in understudied freshwater and terrestrial (inland) environments. Between 2020 and 2022, 457 free-ranging birds across 52 species were received for postmortem examination. The upper gastrointestinal tracts were examined for mesoplastics and other debris (>2 mm) using standard techniques. Twenty-four individuals (5.3%) retained mesodebris and prevalence varied across species, with foraging technique, food type, and foraging substrate all associated with different metrics of debris ingestion. The odds of ingesting any type of anthropogenic mesodebris was nine times higher for non-raptorial species than for raptors. For a subset of raptors (N = 54) across 14 species, the terminal portion of the distal intestinal tract was digested with potassium hydroxide and microparticles were assessed using stereo-microscopy. Although only one of 54 (1.9%) raptors included in both analyses retained mesodebris in the upper gastrointestinal tract, 24 (44.4%) contained microparticles in the distal intestine. This study demonstrates that a variety of Canadian bird species ingest anthropogenic debris in inland systems, and suggests that life history and behaviour are associated with ingestion risk. For raptors, the mechanisms governing exposure and ingestion of mesoplastics appear to be different than those that govern microplastics. Herring gulls (Larus argentatus) and ring-billed gulls (Larus delawarensis) are proposed as ideal sentinels for plastic pollution monitoring in inland systems.

Anthropogenic debris ingestion in a tropical seabird community: Insights from taxonomy and foraging distribution

Oceans have been considered as an unlimited supply of goods and services, but resource extraction and waste disposal became ubiquitous and have been damaging the health of marine ecosystems. Finding suitable sentinel species of the human impacts on the oceans is thus imperative, since they may work as early warnings of disruptive situations. In this study, we investigated how taxonomy and foraging distribution influenced the occurrence of anthropogenic debris among five seabird species inhabiting the tropical Atlantic region. Occurrence of anthropogenic debris was assessed using faeces of breeding individuals as a proxy of ingestion. A total of 268 particles were extracted from all samples. The categories "fragments" and "fibres", as well as the colour "blue", were the most prevalent characteristics across species. There was a high diversity of polymers from cellulosic particles to synthetic plastics (Anthropogenic Cellulosic 26.9 %; Polyester 7.7 %; Varnish 5.8 %; Polypropylene 1.9 %). Species with a more coastal foraging strategy exhibited higher occurrence and number of anthropogenic debris when compared to species foraging comparably more in pelagic areas. This suggests that anthropogenic debris are more prevalent in coastal foraging areas, where human activities occur in higher number and frequency (e.g., fisheries) and sources of freshwater input from inland are at close distance. These results provide more evidence to the growing perception on the ubiquity and diversity of anthropogenic debris in the marine environment, and further support the usefulness of using seabirds as bio-indicators of anthropogenic pollution in both neritic and oceanic regions.

Global research hotspots and trends on microplastics: a bibliometric analysis

In recent years, microplastics have become an integral part of the terrestrial and aquatic environments, which is one of the major concerns of communities around the world. Therefore, it is necessary to know the current status of studies and feasible potentials in the future. This study, conducted an in-depth bibliometric analysis of publications from 1990 to 2022 to present the influential countries, authors, institutes, papers, and journals on microplastics. Findings reveal that there has been a steady increase in microplastic publications and citations in recent years. And, the number of publications and citations has increased 19 and 35 times since 2015. Besides, we performed a comprehensive keyword analysis to show the significant keywords and clusters in this field. In particular, this study used the TF-IDF method as a text-mining analysis to extract the new keywords used in recent years (i.e., 2020-2022). New keywords can draw the attention of scholars to important issues and provide a basis for future research directions.

One-year variation in quantity and properties of microplastics in mussels (Mytilus galloprovincialis) and cockles (Cerastoderma edule) from Aveiro lagoon

As filter feeders, marine bivalves inhabiting estuarine and coastal areas are directly exposed to microplastics (MPs) in water. To assess whether MPs number, and their shape, size, colour, and polymer type present in mussels (Mytilus galloprovincialis) and cockles (Cerastoderma edule) varied over one year, bivalves were collected over the year of 2019 in the lower part of the coastal Aveiro lagoon, Portugal. After extraction from the bivalve's whole-body soft tissues, a subset of the visually inspected particles was randomly separated for identification using the Fourier-transform mid-infrared (FT-MIR) spectroscopy. A fraction of the inspected particles, 26-32% of particles >100 μm, and 59-100% of smaller ones were confirmed as MPs. Concentrations varied within the intervals of 0.77-4.3 items g-1 in mussels and 0.83-5.1 items g-1 in cockles, with the lowest values observed in January. In winter, the accumulation of large-sized fibers was composed of a mixture of plastic types, which contrasted against the most abundant MPs in summer consisting mainly of polyethylene of diverse size classes and shapes. Temperature decrease registered in winter might have triggered a lower filtration rate, resulting in lower MPs concentrations in the whole-soft body tissues of organisms. Different properties of MPs found in bivalves between January-February and August-September appear to reflect changes in the characteristics of MPs available in the Aveiro lagoon.

Microplastics in gastrointestinal tracts of gentoo penguin (Pygoscelis papua) chicks on King George Island, Antarctica

Microplastics (< 5 mm) have been found in marine ecosystems worldwide, even in Antarctic ecosystems. In this study, the stomach and upper intestines of 14 dead gentoo penguin (Pygoscelis papua) chicks were collected and screened for microplastics on King George Island, a gateway to Antarctic research and tourism. A total of 378 microplastics were identified by Fourier-transform infrared spectroscopy, with 27.0 ± 25.3 microplastics per individual. The detected number of microplastics did not increase with the mass of penguin chicks, suggesting no permanent accumulation of microplastics. However, the concentration of microplastics was much higher (9.1 ± 10.8 microplastics per individual within the size range 100-5000 μm) than the previously reported concentration in the penguin feces, and a greater number of smaller microplastics were found. Marine debris surveys near the breeding colony found various plastic (79.3%) to be the most frequent type of beached debris, suggesting that local sources of marine plastic waste could have contributed to microplastic contamination of penguin chicks being fed by parents that forage in nearby seas. This finding confirms the presence of microplastics in an Antarctic ecosystem and suggests the need for stronger waste management in Antarctica and a standardized scheme of microplastic monitoring in this once-pristine ecosystem.

Ingestion of marine debris by juvenile Magellanic penguins (Spheniscus magellanicus) in wintering grounds of coastal Argentina

The occurrence of marine debris in the stomach contents of young male and female Spheniscus magellanicus stranded along the Atlantic coast of northern Argentina during its post-breeding exodus is reported for the first time. Marine debris was found in 15.5 % of 148 dead penguins, with a higher proportion of debris found in females when compared to males. A total of 81 debris items was recorded; plastic and paper each contributed with an equal number of debris whereas rubber contributed with a single item. Chemical identification performed using FTIR/ATR revealed that plastic items were largely LDPE and PA; other polymers included HDPE, PP and PS. The average length of fragmented plastic debris are in line with those reported from penguins stranded along the southern Brazilian coasts. Our study indicates that loads of ingested marine debris were roughly five times lower when compared to the estimates for the species in Brazilian beaches.

Are Microplastics Toxic? A Review from Eco-Toxicity to Effects on the Gut Microbiota

Emerging studies have presented an initial picture of the toxic effects of exposure to environmental micro- and nanoplastics. They have indicated that micro- and nanoplastics may induce toxicity by leading to oxidative stress, energy metabolism disorders, gene damage, and so forth in environmental organisms, marine invertebrates and vertebrates, and laboratory mouse models. In recent years, micro- and nanoplastics have been discovered in human fecal samples, placentas, lung tissue, and even blood; thus, micro- and nanoplastics pose an alarming and ever-increasing threat to global public health. However, current research on the health effects of micro- and nanoplastics and the possible adverse outcomes in humans has only presented the tip of the iceberg. More robust clinical data and basic experiments are still warranted to elucidate the specific relationships and mechanisms. In this paper, we review studies on micro- and nanoplastic toxicity from the perspectives of eco-toxicity, the adverse effects on invertebrates and vertebrates, and the impact of micro- and nanoplastics on the gut microbiota and its metabolites. In addition, we evaluate the toxicological role of micro- and nanoplastic exposure and its potential implications in respect to human health. We also summarize studies regarding preventive strategies. Overall, this review provides insights on micro- and nanoplastic toxicity and its underlying mechanisms, opening up scientific avenues for future in-depth studies.

Detection of anthropogenic fibres in marine organisms: Knowledge gaps and methodological issues

Most studies examining the occurrence of plastics and microplastics in marine organisms have identified anthropogenic fibres, of natural and synthetic origin, as the most commonly occurring category. Anthropogenic fibres may have been chemically treated with additives making them more persistent and a potential threat to marine organisms. However, fibres have often been excluded from analytical data for the difficulties related to the sampling and analytical procedures, including potential overestimation of the results due to airborne contamination. This review aimed to collect and analyse all studies focusing on the interaction between anthropogenic fibres and marine organisms worldwide, highlighting critical issues that need to be overcome for the analysis fibres on marine organisms. Furthermore, emphasis was placed on the species studied in the Mediterranean Sea, which is particularly affected by this type of pollution. Overall, this review shows that fibre pollution is an underestimated threat to marine organisms and that a specific, harmonised protocol for the analysis of different anthropogenic fibres needs to be developed.

Microplastic abundance in feces of lagomorphs in relation to urbanization

The presence of microplastics (MPs) in marine environments has been extensively documented. However, studies of terrestrial species are scarce. Fecal samples (105) of lagomorphs were collected at sites with different levels of urbanization in the Baja California Chaparral and analyzed to quantify and characterize MPs found in the feces. The lagomorph species recorded in the study area are the desert cottontail rabbit (Sylvilagus audubonii), brush rabbit (Sylvilagus bachmani), and black-tailed jackrabbit (Lepus californicus), which play important roles in the food web of the chaparral ecosystem. Microplastics were identified using attenuated total reflectance Fourier transform infrared spectroscopy. Microplastics were detected in 49 % of the samples, with fibers being the dominant shape found (72 %). Most (75 %) of the MPs were <1 mm in size, with a mean length of 0.93 ± 0.99 mm (median 0.60 mm, range 0.02 - <5 mm). Polyamide was the dominant polymer (54 %), indicating that MPs are likely derived from textiles; polyethylene was also abundant (27 %). A difference was also observed in the abundance of MPs in feces from sites with different levels of urbanization, with the highest abundance in feces from the urban sites.

First assessment of debris pollution in the gastrointestinal content of juvenile Magellanic penguins (Spheniscus magellanicus) stranded on the west south Atlantic coasts

This paper provides the first evidence of debris pollution, including plastic, in juvenile Magellanic penguins (Spheniscus magellanicus) found stranded on the Atlantic coast of southern Buenos Aires Province, Argentina. Macro-, meso- and microparticles of anthropogenic origin were observed in 100 % of the studied birds, with debris abundance ranging between 33 and 200 items/bird. Microparticles represented 91 % of the total debris and 97 % of them were fibers. Black particles were the most abundant (30 %), followed by transparent (26 %), blue (14 %), yellow (10.3 %), and red (10 %). Infrared and Raman spectroscopy identified 62.7 % of the total particles as plastics, with polypropylene (27.8 %) and polyester (21.6 %) being the most abundant polymers. Semi-synthetic cellulosic fibers, metallic particles, and pigments were also found. The presence of metallic microparticles was suggested for the first time in penguins. Stranded juvenile Magellanic penguins are proposed as promising bioindicators of plastic pollution in the South Atlantic.

Foraging strategy influences the quantity of ingested micro- and nanoplastics in shorebirds

Coastlines, including estuaries, mudflats, and beaches, are particularly susceptible to plastic pollution, which can accumulate from both marine and terrestrial sources. While numerous studies have confirmed the presence of microplastics (1-5 mm) along coastlines, few have focused on very small particles (<1 μm) or quantified exposure within the organisms that inhabit these areas, such as shorebirds. Here, we quantified small plastics (200 nm-70 μm) in two resident shorebird species in Tasmania, and compared this to quantities found in the surrounding sediments in order to investigate the potential exposure and transfer of particles within these ecosystems. Analysis was performed using a combination of flow cytometry for quantification of micro- and nanoplastics (200 nm-70 μm), and μm-FT-IR for validation and polymer identification of particles >5.5 × 5.5 μm. Micro- and nano-plastics were detected in 100% of guano samples from surface-feeding Eastern Hooded Plovers (Thinornis cucullatus) and 90% of Australian Pied Oystercatcher (Haematopus longirostris) guano, a species that forages for coastal invertebrates at 60-90 mm depth, and 100% of beach sediments. Hooded Plover guano contained 32 × more plastics, on average, than Pied Oystercatcher guano. Interestingly, the abundance of plastic particles within sediments collected from shorebird foraging sites did not appear to have a significant effect on the number of plastics the birds had ingested, suggesting the difference between species is likely a result of other variables, such as prey selection. The results of this study highlight the importance of including techniques that provide quantitative data on the abundance and size of the smallest possible particle sizes, and demonstrate the significant proportion of small plastics that are 'missed' using standard analysis tools.

The one-two punch of plastic exposure: Macro- and micro-plastics induce multi-organ damage in seabirds

Plastic pollution in the world's oceans is ubiquitous and increasing. The environment is inundated with microplastics (< 1 mm), and the health effects of these less conspicuous pollutants is poorly known. In addition, there is now evidence that macroplastics can release microplastics in the form of shedding or digestive fragmentation, meaning there is potential for macroplastic exposure to induce direct and indirect pathology through microplastics. Therefore, there is an urgent need for data from wild populations on the relationship between macro- and microplastic exposure and the potential compounding pathological effects of these forms of plastics. We investigated the presence and impact of microplastics in multiple tissues from Flesh-footed Shearwaters Ardenna carneipes, a species that ingests considerable quantities of plastics, and used histopathological techniques to measure physiological responses and inflammation from the plastics. All organs examined (kidney, spleen, proventriculus) had embedded microplastic particles and this correlated with macroplastic exposure. Considerable tissue damage was recorded, including a significant reduction in tubular glands and rugae in the proventriculus, and evidence of inflammation, fibrosis, and loss of organ structures in the kidney and spleen. This indicates macroplastics can induce damage directly at the site of exposure, while microplastics can be mobilised throughout the body causing widespread pathology. Collectively, these results indicate the scope and severity of the health impacts of plastic pollution may be grossly underestimated.

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.

Thrushes (Aves: Passeriformes) as indicators of microplastic pollution in terrestrial environments

Microplastic pollution is one of the leading global conservation issues. The aim of this study was to investigate the occurrence of microplastics in the gastrointestinal tracts of Common Blackbirds Turdus merula (N = 16) and Song Thrushes Turdus philomelos (N = 18), songbirds with exceptionally terrestrial lifestyles and a wide distribution range. We searched for microplastics of over 100 μm in size and assessed whether their contamination differed regarding the age of the birds and the time of year. We used birds that had died as a result of collision with anthropogenic infrastructure, which were sampled during wildlife monitoring of anthropogenic infrastructures and citizen science projects in north-eastern Poland. We found that all the analysed individuals contained microplastic in their gastrointestinal tracts, which were classified as fibers, fragments, films and pellets. A total number of 1073 microplastics were observed, mostly consisting of fibers (84 %) and films (10 %) below 1 mm in size. The dominant colours of microplastics were transparent (75 %) and brown (14 %). The species average microplastic concentration was higher in Song Thrushes (40.1) than Common Blackbirds (21.9), however the difference was not statistically significant. Moreover, we found no seasonal or age-related differences in microplastic ingestion in either species. While our results show a ubiquity of microplastics in terrestrial environments, they also indicate that thrushes have the potential to be used as indicators of microplastic pollution in terrestrial ecosystems.

Marine litter pollution of breeding colony and habitat use patterns of Black-tailed gulls in South Korea

Marine litter can affect the survival of the breeding population in seabird colonies. In this study, five 5 m × 5 m quadrats were installed at a Black-tailed gull (Larus crassirostris) breeding colony on Nan Island to collect marine litter and regurgitated pellets, from which the types, sizes, and quantities of marine litter were identified. Global positioning system (GPS) devices were attached to five adult gulls to investigate their major foraging habitats during the breeding period. Eighty-two pieces of marine litter were found, of which 74.4 % were related to fishing; all pellets contained fishing-related marine litter. Over half of the foraging habitats included fishing areas (ports and fish farms). This study is the first to quantitatively demonstrate the exposure of breeding colonies of Black-tailed gulls, the most dominant Korean seabird, to marine litter pollution during the breeding period; the birds forage predominantly in fishing areas close to their breeding colonies during this period.

A new approach to extracting biofilm from environmental plastics using ultrasound-assisted syringe treatment for isotopic analyses

Plastics are one of the ubiquitous and artificial types of substrates for microbial colonization and biofilm development in the aquatic environment. Characterizing plastic-associated biofilms is key to the better understanding of organic material and mineral cycling in the "Plastisphere"-the thin layer of microbial life on plastics. In this study, we propose a new method to extract biofilms from environmental plastics, in order to evaluate the properties of biofilm-derived organic matter through stable carbon (δ¹³C) and nitrogen (δ¹⁵N) isotope signatures and their interactions with radionuclides especially radiocesium (¹³⁷Cs). The extraction method is simple and cost-effective, requiring only an ultrasonic bath, disposable plastic syringes, and a freeze drier. After ultrasound-assisted separation from the plastics, biofilm samples were successfully collected via a sequence of syringe treatments, with less contamination from plastics and other mineral particles. Effective removal of small microplastics from the experimental suspension was satisfactorily achieved using the method with syringe treatments. Biofilm-derived organic matter samples (14.5-65.4 mg) from four river mouths in Japan showed ¹³⁷Cs activity concentrations of <75 to 820 Bq·kg^-1 biofilm (dw), providing evidence that environmental plastics, mediated by developed biofilms, serve as a carrier for ¹³⁷Cs in the coastal riverine environment. Significant differences in the δ¹³C and δ¹⁵N signatures were also obtained for the biofilms, indicating the different sources, pathways, and development processes of biofilms on plastics. We demonstrate here a straightforward method for extracting biofilms from environmental plastics; the results obtained with this method could provide useful insights into the plastic-associated nutrient cycling in the environment.

Plastic Debris in Nests of Two Water Bird Species Breeding on Inland Saline Lakes in a Mediterranean Biosphere Reserve

Despite more studies being carried out to know the impacts associated with plastic debris and much effort being spent on marine ecosystems, the impacts of plastics on terrestrial and freshwater species remain largely unknown. Here, we explored the presence of anthropogenic materials in nests of two wader species, the gull-billed tern (Gelochelidon nilotica) and the black-winged stilt (Himantopus himantopus), breeding on the inland salt lakes in the “La Mancha Húmeda” Biosphere Reserve, Central Spain. We revealed the presence of anthropogenic debris, mainly macroplastics (>5 mm), in 2.4% and 12.5% of the sampled nests of the gull-billed tern and the black-winged stilt, respectively. The fragments found in nests ranged from 8 mm to 257 mm for the gull-billed tern and from 7 mm to 19 mm for the black-winged stilt. This debris showed no clear pattern of color or size and probably originated both in the agricultural activities in the surroundings and domestic refuse. Although we did not detect any pernicious impacts on adults or chicks (e.g., entangled, injured, or dead individuals), the presence of plastics and other human waste directly placed in nests located in a protected area should warn us about the ubiquity of these pollutants, and the endocrine and immunological effects, among others, that may reduce the recruitment of new animals to the population should be assessed.

Co-contaminants of microplastics in two seabird species from the Canadian Arctic

Through ingestion and subsequent egestion, Arctic seabirds can bioaccumulate microplastics at and around their colony breeding sites. While microplastics in Arctic seabirds have been well documented, it is not yet understood to what extent these particles can act as transport vehicles for plastic-associated contaminants, including legacy persistent organic pollutants (POPs), trace metals, and organic additives. We investigated the occurrence and pattern of organic and inorganic co-contaminants of microplastics in two seabird species from the Canadian Arctic - northern fulmar (Fulmarus glacialis) and black-legged kittiwake (Rissa tridactyla). We found that fulmars had higher levels of plastic contamination and emerging organic compounds (known to be plastic additives) than kittiwakes, whereas higher concentrations of legacy POPs were found in kittiwakes than the fulmars. Furthermore, fulmars, the species with the much larger foraging range (∼200 km), had higher plastic pollution and overall contaminant burdens, indicating that birds may be acting as long-range transport vectors for plastic-associated pollution. Our results suggest a potential connection between plastic additive contamination and plastic pollution burdens in the bird stomachs, highlighting the importance of treating plastic particles and plastic-associated organic additives as co-contaminants rather than separate pollution issues.

Distribution characteristics of microplastics in surface and subsurface Antarctic seawater

Microplastics have attracted worldwide attention due to their potential threat to the marine ecosystem, with such pollutants even detected in the polar seas. Although in-depth research on microplastics has increased in recent years, studies in Antarctic waters remain relatively scarce compared with coastal waters and open oceans. In this study, microplastics in surface and subsurface Antarctic waters were investigated. The average microplastic abundance in the surface water was 0.10 ± 0.14 items/m³, with highest abundance in the Ross Sea, and the average microplastic abundance in the subsurface water was 1.66 ± 1.20 items/m³, with highest abundance in the Dumont d'Urville Sea. Polyester was the main microplastic in the surface waters (87.3%), while polypropylene (33.1%), polyester (28.7%), and polyethylene (22.8%) were the dominant microplastics in the subsurface waters. Results indicate that microplastic pollution in Antarctic waters may come from the Antarctic continent as well as southward transport from the ocean at mid- and low latitudes.

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.

Persistence of avian influenza virus (H9N2) on plastic surface

Plastics have been found to be colonized with pathogens and may become vectors for transmission of diseases. In this study, we evaluated the persistence of H9N2 avian influenza virus (AIV) on the surfaces of various plastics (PP, PE, PS, PET, PVC, PMMA) under different environmental conditions using glass and stainless steel for comparison. Our results showed that the RNA abundance of AIV on plastics was decreased over time but still detectable 14 days after AIV had been dropped on plastic surfaces. Low temperature (4 °C) was more favorable for AIV RNA preservation and infectivity maintenance. The abundance of AIV RNA was significantly greater on polyethylene terephthalate (PET) than that on glass and stainless steel at higher temperature (i.e., 25 °C and 37 °C) and lower humidity (<20% and 40-60%) (p < 0.05). Infectivity assay showed that AIV infectivity was only maintained at 4 °C after 24 h of incubation. Taken together, the persistence of AIV was more affected by environmental factors than material types. Plastics were able to preserve viral RNA more effectively in relatively high-temperature or low-humidity environments. Our study indicates that environmental factors should be taken into consideration when we evaluate the capacity of plastics to spread viruses.

Micro(nano)plastics pollution and human health: How plastics can induce carcinogenesis to humans?

Microplastics (MPs) and nanoplastics (NPs) are key indicators of the plasticine era, widely spread across different ecosystems. MPs and NPs become global stressors due to their inherent physicochemical characteristics and potential impact on ecosystems and humans. MPs and NPs have been exposed to humans via various pathways, such as tap water, bottled water, seafood, beverages, milk, fish, salts, fruits, and vegetables. This paper highlights MPs and NPs pathways to the food chains and how these plastic particles can cause risks to human health. MPs have been evident in vivo and vitro and have been at health risks, such as respiratory, immune, reproductive, and digestive systems. The present work emphasizes how various MPs and NPs, and associated toxic chemicals, such as polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs), impact human health. Polystyrene (PS) and polyvinyl chloride (PVC) are common MPs and NPs, reported in human implants via ingestion, inhalation, and dermal exposure, which can cause carcinogenesis, according to Agency for Toxic Substances and Disease Registry (ATSDR) reports. Inhalation, ingestion, and dermal exposure-response cause genotoxicity, cell division and viability, cytotoxicity, oxidative stress induction, metabolism disruption, DNA damage, inflammation, and immunological responses in humans. Lastly, this review work concluded with current knowledge on potential risks to human health and knowledge gaps with recommendations for further investigation in this field.

Plastic Interactions with Pollutants and Consequences to Aquatic Ecosystems: What We Know and What We Do Not Know

Plastics are a group of synthetic materials made of organic polymers and some additives with special characteristics. Plastics have become part of our daily life due to their many applications and uses. However, inappropriately managed plastic waste has raised concern regarding their ecotoxicological and human health risks in the long term. Due to the non-biodegradable nature of plastics, their waste may take several thousands of years to partially degrade in natural environments. Plastic fragments/particles can be very minute in size and are mistaken easily for prey or food by aquatic organisms (e.g., invertebrates, fishes). The surface properties of plastic particles, including large surface area, functional groups, surface topography, point zero charge, influence the sorption of various contaminants, including heavy metals, oil spills, PAHs, PCBs and DDT. Despite the fact that the number of studies on the biological effects of plastic particles on biota and humans has been increasing in recent years, studies on mixtures of plastics and other chemical contaminants in the aquatic environment are still limited. This review aims to gather information about the main characteristics of plastic particles that allow different types of contaminants to adsorb on their surfaces, the consequences of this adsorption, and the interactions of plastic particles with aquatic biota. Additionally, some missing links and potential solutions are presented to boost more research on this topic and achieve a holistic view on the effects of micro- and nanoplastics to biological systems in aquatic environments. It is urgent to implement measures to deal with plastic pollution that include improving waste management, monitoring key plastic particles, their hotspots, and developing their assessment techniques, using alternative products, determining concentrations of micro- and nanoplastics and the contaminants in freshwater and marine food-species consumed by humans, applying clean-up and remediation strategies, and biodegradation strategies.

The influence of seabirds on their breeding, roosting, and nesting grounds: a systematic review and meta-analysis

Seabird species worldwide are integral to both marine and terrestrial environments, connecting the two systems by transporting vast quantities of marine-derived nutrients and pollutants to terrestrial breeding, roosting, and nesting grounds via the deposition of guano and other allochthonous inputs (e.g., eggs, feathers). We conducted a systematic review and meta-analysis and provide insight into what types of nutrients and pollutants seabirds are transporting, the influence these subsidies are having on recipient environments, with a particular focus on soil, and what may happen if seabird populations decline. The addition of guano to colony soils increased nutrient levels compared to control soils for all seabirds studied, with cascading positive effects observed across a range of habitats. Deposited guano sometimes led to negative impacts, such a guanotrophication, or guano-induced eutrophication, which was often observed where there was an excess of guano or in areas with high seabird densities. While the literature describing nutrients transported by seabirds is extensive, literature regarding pollutant transfer is comparatively limited, with a focus on toxic and bioaccumulative metals. Research on persistent organic pollutants and plastics transported by seabirds is likely to increase in coming years. Studies were limited geographically, with hotspots of research activity in a few locations, but data were lacking from large regions around the world. Studies were also limited to seabird species listed as Least Concern on the IUCN Red List. As seabird populations are impacted by multiple threats and steep declines have been observed for many species worldwide, gaps in the literature are particularly concerning. The loss of seabirds will impact nutrient cycling at localised levels and potentially on a global scale as well, yet it is unknown what may truly happen to areas that rely on seabirds if these populations disappear.

Microplastics in the high-altitude Himalayas: Assessment of microplastic contamination in freshwater lake sediments, Northwest Himalaya (India)

In this study, we assess the magnitude, type, and sources of microplastic (MP) in lake bottom sediments collected from freshwater Anchar Lake, located in the Kashmir Valley, Northwest Himalaya. The MP identification was done on twenty-four lake bottom sediment samples under a stereo-microscope, and their polymer compositions were characterized using an Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR) spectroscopy. The study reveals that 606 ± 360 (average ± SD, n = 24) numbers of MP were present per kilogram of dry sediment samples, with fibers (91%), fragments/films (8%), and pellets (1%) dominating the shape groups. Polyamide (PA, 96%) was the dominant polymer composition present in the sediment samples, followed by polyethylene terephthalate (PET, 1.4%), polystyrene (PS, 1.4%), polyvinyl chloride (PVC, 0.9%), and polypropylene (PP, 0.7%). Polymer Hazard Index (PHI) and Pollution Load Index (PLI) were used to evaluate the quality of sediments. It was noted that high PHI values (>1000) were due to the presence of PVC polymer. According to PLI values, sediments in the Anchar lake are less contaminated with MP. We conclude that MP in the Anchar Lake have a complex source derived mostly from the automobile, textile, and packaging industries.

The potential of aerial insectivores for monitoring microplastics in terrestrial environments

Limited research has been conducted on microplastics in terrestrial ecosystems and biota, despite being some of the most ubiquitous environmental pollutants. We investigated the presence of microplastics (over 125 μm) in tree swallow (Tachicyneta bicolor) chicks (10 d. o.), an aerial insectivore whose diet involves terrestrial and/or freshwater sources. Swallows nested immediately downstream (300 m) of the discharge pipe of a large, urban wastewater treatment plant (WWTP) or at a rural conservation area (40 km apart). Anthropogenic microparticles (including microplastics) were identified in nearly all WWTP chicks (90%; N = 20) and reference chicks (83%; N = 20). All microparticles were fibers (100%) in the gastro-intestinal (GI) tracts of WWTP nestlings, whereas unexpectedly, they were more diverse in the GI tracts of reference chicks, with ~15% characterized as pre-production plastic pellets. The fecal sacs of most nestlings (90%) contained microparticles, and all were characterized as fibers suggesting their excretion by tree swallows. Compared to WWTP chicks, the reference chicks had more microparticles in their fecal sacs and larger particles (length, width) in their GI tracts, likely reflecting the more aquatic-based diet of the reference chicks fed insects caught adjacent to the nearby dam, compared to the more terrestrial-based diet of the WWTP chicks. The numbers of microparticles were not correlated between GI tracts and fecal sacs, nor with the chicks' condition or size (weight, organs, feathers). We recommend sampling macroinvertebrate prey to permit stronger conclusions regarding WWTPs as possible sources of microplastics for swallows, and to determine if such macroinvertebrates may be a non-lethal method to characterize microparticle diversity ingested by birds as presently identified in chicks' GI tracts. We conclude that sampling fecal sacs only, while not indicative of the diversity of microplastics ingested by terrestrial passerines (e.g., tree swallows), is useful for determining their exposure to microparticles.

Distribution and characterization of plastic debris pollution along the Poompuhar Beach, Tamil Nadu, Southern India

The present study was carried out to determine the characteristics, distribution, and abundance of plastic debris in 25 sediment samples collected from the Poompuhar beach, southeast coast of India. The result reveals that the mean plastic debris abundance was 42 ± 27 particles/m² dry weight (dw) (1 SD, n = 25) with higher concentrations in the river mouth. The dominant shapes in the study area were fragment (70.7%), followed by fiber (20.7%), and pellet-shaped (8.6%). The dominant colors of the plastic debris were: white-colored (47%) followed by blue (28%) and green (14%). The study further reveals that the dominant polymer type was polyethylene (PE, 63.4%), followed by nylon (PA, 16.9), polyvinyl chloride (PVC, 15.5%), polypropylene (PP, 3.1%), and polystyrene (PS, 1.1%). In the study area, the main source of plastic debris was from land-based fishing and tourism activities, and rainwater runoff from the Cauvery River.

Microbial colonizers of microplastics in an Arctic freshwater lake

Microplastics (MPs) have been found everywhere as they are easily transported between environmental compartments. Through their transport, MPs are quickly colonized by microorganisms; this microbial community is known as the plastisphere. Here, we characterized the plastisphere of three MPs, one biodegradable (PHB) and two non-biodegradables (HDPE and LDPE), deployed in an Arctic freshwater lake for eleven days. The plastisphere was found to be complex, confirming that about a third of microbial colonizers were viable. Plastisphere was compared to microbial communities on the surrounding water and microbial mats on rocks at the bottom of the lake. Microbial mats followed by MPs showed the highest diversity regarding both prokaryotes and eukaryotes as compared to water samples; however, for fungi, MPs showed the highest diversity of the tested substrates. Significant differences on microbial assemblages on the three tested substrates were found; regarding microbial assemblages on MPs, bacterial genera found in polar environments such as Mycoplana, Erythromicrobium and Rhodoferax with species able to metabolize recalcitrant chemicals were abundant. Eukaryotic communities on MPs were characterized by the presence of ciliates of the genera Stentor, Vorticella and Uroleptus and the algae Cryptomonas, Chlamydomonas, Tetraselmis and Epipyxis. These ciliates normally feed on algae so that the complexity of these assemblages may serve to unravel trophic relationships between co-existing taxa. Regarding fungal communities on MPs, the most abundant genera were Betamyces, Cryptococcus, Arrhenia and Paranamyces. MPs, particularly HDPE, were enriched in the sulI and ermB antibiotic resistance genes (ARGs) which may raise concerns about human health-related issues as ARGs may be transferred horizontally between bacteria. This study highlights the importance of proper waste management and clean-up protocols to protect the environmental health of pristine environments such as polar regions in a context of global dissemination of MPs which may co-transport microorganisms, some of them including ARGs.

Microplastics in Wastewater and Drinking Water Treatment Plants: Occurrence and Removal of Microfibres

Microplastics (MPs), and specifically microfibres (MPFs), are ubiquitous in water bodies, including wastewater and drinking water. In this work, a thorough literature review on the occurrence and removal of MPs, and specifically MPFs in WWTPs and DWTPs, has been carried out. When the water is treated, an average microfiber removal efficiency over 70% is achieved in WWTPs and DWTPs. These high percentages are still inefficient for avoiding the presence of a large number of microfibres in treated wastewater and also in tap water. RSF, DAF, oxidation ditch and CAS processes have been described as the most efficient treatments for eliminating MPFs from wastewater treatment. It is remarkable the wide range of the data reported on this topic; for example, treated wastewater contains between not detected and 347 MPFs/L, whereas tap water contains between not detected and 168 MPFs/L. Microfibres constitute more than half of the MPs found in treated wastewater and sewage sludge, whereas in DWTP effluents the percentage of MPFs is around 32%. Nevertheless, the relative amount of MPFs reported in tap water is notably higher (71%). Microfibres from WWTPs are discharged to the environment, being a source of MP pollution. Additionally, MPs released by DWTPs directly enter the drinking water lines, which constitute a direct route for MP human consumption, so that it has been estimated that an adult may ingest an average value of 7500 MPFs per year only via tap water. Thus, this review provides an update on the performance of WWTPs and DWTPs in removing MPs from water, which is an issue of great interest.

Understanding the occurrence and fate of microplastics in coastal Arctic ecosystems: The case of surface waters, sediments and walrus (Odobenus rosmarus)

The Arctic ecosystem receives contaminants transported through complex environmental pathways - such as atmospheric, riverine and oceanographic transport, as well as local infrastructure. A holistic approach is required to assess the impact that plastic pollution may have on the Arctic, especially with regard to the unseen microplastics. This study presents data on microplastics in the Arctic fjords of western Svalbard, by addressing the ecological consequences of their presence in coastal surface waters and sediment, and through non-invasive approaches by sampling faeces from an apex predator, the benthic feeder walrus (Odobenus rosmarus). Sample locations were chosen to represent coastal areas with different degrees of anthropogenic pollution and geographical features (e.g., varying glacial coverage of catchment area, winter ice cover, traffic, visitors), while also relevant feeding grounds for walrus. Microplastics in surface water and sediments ranged between <LOD (limit of detection)-3.5 particles/m³ and <LOD-26 particles/kg dry weight, respectively. This study shows that microplastics may also enter the Arctic food web as the microplastic concentration in walrus faeces were estimated at an average of 34 particles/kg. Polyester was identified by Fourier transformation infrared spectroscopy (FT-IR) as the most common plastic polymer (58% in water, 31% in walrus), while fibres were the most common shape (65% water, 71% in sediment, 70% walrus). There was no significant difference in microplastic occurrence between water samples from populated or remote fjords, suggesting that microplastics are a ubiquitous contaminant which is available for interaction with Arctic marine animals even at distances from settlements. The present study contributes to our understanding of microplastics in the remote Arctic ecosystem. It also identifies the potential of non-invasive sampling methods for investigating Arctic pinnipeds. This approach will need further development and standardisation before utilisation to monitor plastic pollution in other marine mammals.

The effect of microplastics on behaviors of chiral imidazolinone herbicides in the aquatic environment: Residue, degradation and distribution

The pollution of aquatic environments by microplastics and herbicides has become a global concern. This study was focused on imazamox, imazapic, and imazethapyr sorption to polypropylene microplastics in water. And the potential effects of microplastics on herbicide enantiomer degradation and distributions in water, sediment, and water-sediment microcosms were investigated. Adsorption experiment results indicated that herbicide sorption to microplastics involved both chemisorption and physical adsorption. Degradation experiment results indicated that microplastics could markedly increase herbicide persistence in water and sediment. Marked stereoselective degradation was not found for the three herbicides in water and sediment, but stereoselective degradation of imazapic in water containing microplastics was found. The water-sediment microcosms experiment results indicated that microplastics have significant effect on stereoselectivity degradation and distribution in water and water-sediment microcosms for imazapic, and have little effect on stereoselectivity behaviors of imazamox and imazethapyr in water-sediment systems. Furthermore, the microcosm experiment results also indicated that herbicides can partition between water and microplastics and that microplastics could affect herbicide persistence and distributions in aquatic environments. The present study provides new insights into the fate of chiral pollutants in aquatic environments containing microplastics, and contributes to understanding behaviors of herbicides and microplastics in aquatic environments.

Microplastics in polar regions: An early warning to the world's pristine ecosystem

The menace of plastic which is polluting the ocean has emerged as a global problem. It is well-known to everyone that the ultimate end for most of the plastic debris is the ocean. The distribution of plastic rubbish in the oceans is strongly influenced by hydrodynamic properties of water. The continuous break down of plastic objects, as a consequence of thermal, chemical and biological processes along with various environmental factors, results into microplastics (MPs). The microplastics are those particles which are deriving pallets of plastic, having length of less than 5 mm or 0.2 in. Nowadays microplastics are everywhere in the waters all around the world. The high dispersion pattern of oceanic currents takes away microplastics in the entire ocean even to remote areas, like the Polar Regions. Microplastics are difficult to remove from the ocean and the ingestion of these particles by several consumers of different trophic levels like benthos, birds, and fishes is a threat to the diverse food webs and ecosystems. Different scientific investigations have ascertained that a significant concentration of MPs are present in various marine ecosystems globally including the Polar region (both Arctic and Antarctic), and in the upcoming future, the condition is expected to get worse. The objective of this review is to establish a baseline evidence for the availability of microplastics in the polar region. For this reason, the state of the art of knowledge on microplastics in Polar Regions was studied.

Plastic microfibre pollution: how important is clothes' laundering?

Plastic microfibre pollution produced by domestic and commercial laundering of synthetic textiles has recently been incriminated in the press and the scientific literature as the main source (up to 90%) of primary microplastics in the oceans. Polyethylene terephthalate (PET) is the most common microfibre encountered. This review aims to provide updated information on worldwide plastic microfibre pollution caused by textile laundering and some possibilities for its control. Release of microfibres during domestic washing and tumble drying, their fate in wastewater treatment plants (WWTPs) and the oceans, and their environmental effects on the aquatic biota are discussed, as well as potential control methods at the levels of textile modification and laundry procedures. Environmental effects on aquatic biota are important; as a result of their small size and length-to-diameter ratio, microfibers are more effectively incorporated by organisms than other plastic particle groups. Simulation laundering studies may be useful in the development of a Standard Test Method and modification of WWTPs may reduce microfibre release into aquatic systems. However, improvements will be necessary in textile design and appliance design, and recommendations should be made to consumers about reducing their personal impact on the environment through their laundering choices, which can include appliances, fabric care products and washing conditions. Official regulation, such as that introduced recently by the French government, may be necessary to reduce plastic microfibre release from clothes' laundering.

Metals in microplastics: determining which are additive, adsorbed, and bioavailable

Microplastics from the North Atlantic Gyre deposited on Guadeloupe beaches were sampled and characterized. A new method is developed to identify which elements were present as additives in these microplastics. The method used both acidic leaching and acidic digestion. Several elements (Al, Zn, Ba, Cu, Pb, Cd, Mn, Cr) were identified as pigments. Furthermore, some elements used as additives to plastics (especially the non-essential elements) seem to contribute to most of the acidic leaching, suggesting that these additives can leach and adsorb onto the surface microplastics, becoming bioavailable. Based on the acidic leaching element content, only Cd should represent a danger for fish when ingested. However, further studies are needed to determine the potential synergetic effect on health caused by the ingestion of several elements and microplastics.