Microplastic contamination in filter-feeding oyster Saccostrea cuccullata: Novel insights in a marine ecosystem

Microplastic (MP) pollution has become a pressing global concern. Oysters are well-known filter feeders who ingest food by filtering microscopic particles suspended in the surrounding water. Along with organic matter, filter-feeding also causes accidental ingestion of MP by oysters. Hence, the aim of the current investigation is to understand the MP contamination in filter-feeding oysters. A total of 500 specimens of oyster Saccostrea cuccullata collected from the intertidal zone of five sampling locations on the Gujarat coast, India. Specimens underwent analysis following established protocols. Each specimen was found to exhibit MP contamination, showing an abundance of 2.72 ± 1.98 MPs/g. A negative relationship was found between shell length and MP abundance. Predominantly, fibers were documented across all study sites. Black, blue, and red-colored MPs with 1-2 mm sizes were most dominant. MP polymer composition was identified as polyethylene terephthalate and polypropylene. Findings provide baseline information on levels of MPs contamination, which can be used to monitor future effects of MP pollution.

Identification of different plastic types and natural materials from terrestrial environments using fluorescence lifetime imaging microscopy

Environmental pollution by plastics is a global issue of increasing concern. However, microplastic analysis in complex environmental matrices, such as soil samples, remains an analytical challenge. Destructive mass-based methods for microplastic analysis do not determine plastics' shape and size, which are essential parameters for reliable ecological risk assessment. By contrast, nondestructive particle-based methods produce such data but require elaborate, time-consuming sample preparation. Thus, time-efficient and reliable methods for microplastic analysis are needed. The present study explored the potential of frequency-domain fluorescence lifetime imaging microscopy (FD-FLIM) for rapidly and reliably identifying as well as differentiating plastics and natural materials from terrestrial environments. We investigated the fluorescence spectra of ten natural materials from terrestrial environments, tire wear particles, and eleven different transparent plastic granulates <5 mm to determine the optimal excitation wavelength for identification and differentiation via FD-FLIM under laboratory conditions. Our comparison of different excitation wavelengths showed that 445 nm excitation exhibited the highest fluorescence intensities. 445 nm excitation was also superior for identifying plastic types and distinguishing them from natural materials from terrestrial environments with a high probability using FD-FLIM. We could demonstrate that FD-FLIM analysis has the potential to contribute to a streamlined and time-efficient direct analysis of microplastic contamination. However, further investigations on size-, shape-, color-, and material-type detection limitations are necessary to evaluate if the direct identification of terrestrial environmental samples of relatively low complexity, such as a surface inspection soil, is possible.

A realistic combined exposure scenario: effect of microplastics and atrazine on Piaractus mesopotamicus

Microplastics, considered emerging environmental contaminants resulting from plastic degradation, are discovered in diverse aquatic ecosystems and can be unintentionally ingested by fish. Therefore, it is essential to characterize their interaction with other contaminants, such as agrochemicals, in aquatic environments. This study aimed to assess histological, enzymatic, and genotoxic biomarkers in juvenile pacú (Piaractus mesopotamicus) exposed to polyethylene (PE) microplastic particles and the herbicide atrazine, individually or combined, for 15 days. Four treatments were used: a negative control (CON), PE in the fish diet (0.1% w/w, FPE), atrazine through water (100 μg L-1, ATZ), and the mixture (ATZ+FPE). Results confirmed histological alterations in gills (edema and lamellar fusion) and liver (necrotic areas and congestion) of fish exposed to ATZ and ATZ+FPE. The number of goblet cells increased in the posterior intestine of fish under ATZ+FPE compared to CON and FPE. Enzyme activities (CAT, GST, AChE, and BChE) significantly increased in ATZ+FPE compared to CON. However, no genotoxic effect was demonstrated. These findings provide insights into the complex impacts of simultaneous exposure to atrazine and microplastics, emphasizing the need for continued research to guide effective environmental management strategies against these contaminants that represent a risk to aquatic organisms.

Evidence of parental transfer of nanoplastics in pea (Pisum sativum) plants

The increasing abundance of nanoplastics in the environment is a cause of serious concern and its acute and chronic effects on ecosystems need to be thoroughly investigated. Toward this end, this study investigated the parental transfer of nanoplastics by chronically exposing Pisum sativum (pea) plants to nanoplastics through soil medium. We observed the presence of nanoplastics in harvested fruits and a subsequent generation of plants replanted in uncontaminated soil using confocal laser scanning microscopy. The fluorescence was located in the cell wall of the vascular bundles, but not in the epidermis, indicating the parental transfer of nanoplastics. In addition, we determined the effects of nanoplastics on the health of subsequent plant generations by estimating the reproductive factors and measuring the content of individual nutrients in peas. Decreases in crop yield and fruit biomass, in addition to changes in nutrient content and composition, were noted. The transgenerational effects of nanoplastics on plants can profoundly impact terrestrial ecosystems, including both plant species and their predators, raising critical safety concerns. Our findings highlight the evidence of parental transfer of nanoplastics in the soil through plants and shows that the chronic effects of nanoplastics on plants may pose a threat to the food supply.

Microplastics alter soil structure and microbial community composition

Microplastics (MPs), including conventional hard-to-biodegrade petroleum-based and faster biodegradable plant-based ones, impact soil structure and microbiota in turn affecting the biodiversity and functions of terrestrial ecosystems. Herein, we investigated the effects of conventional and biodegradable MPs on aggregate distribution and microbial community composition in microhabitats at the aggregate scale. Two MP types (polyethylene (PE) and polylactic acid (PLA) with increasing size (50, 150, and 300 μm)) were mixed with a silty loam soil (0-20 cm) at a ratio of 0.5 % (w/w) in a rice-wheat rotation system in a greenhouse under 25 °C for one year. The effects on aggregation, bacterial communities and their co-occurrence networks were investigated as a function of MP aggregate size. Conventional and biodegradable MPs generally had similar effects on soil aggregation and bacterial communities. They increased the proportion of microaggregates from 17 % to 32 %, while reducing the macroaggregates from 84 % to 68 %. The aggregate stability decreased from 1.4 mm to 1.0-1.1 mm independently of MP size due to the decline in the binding agents gluing soil particles (e.g., microbial byproducts and proteinaceous substances). MP type and amount strongly affected the bacterial community structure, accounting for 54 % of the variance. Due to less bioavailable organics, bacterial community composition within microaggregates was more sensitive to MPs addition compared to macroaggregates. Co-occurrence network analysis revealed that MPs exacerbated competition among bacteria and increased the complexity of bacterial networks. Such effects were stronger for PE than PLA MPs due to the higher persistence of PE in soils. Proteobacteria, Bacteroidetes, Chloroflexi, Actinobacteria, and Gemmatimonadetes were the keystone taxa in macroaggregates, while Actinobacteria and Chloroflexi were the keystone taxa in microaggregates. Proteobacteria, Actinobacteria, and Chloroflexi were the most sensitive bacteria to MPs addition. Overall, both conventional and biodegradable MPs reduced the portion of large and stable aggregates, altering bacterial community structures and keystone taxa, and consequently, the functions.

Straw incorporation into microplastic-contaminated soil can reduce greenhouse gas emissions by enhancing soil enzyme activities and microbial community structure

Microplastic (MP) contamination poses a substantial threat to agroecosystems, disrupting soil properties, nutrient cycles, and microbial communities and ultimately affecting plant growth and ecosystem resilience. The effects of straw addition on the storage of soil organic carbon (SOC) and greenhouse gas emissions have been extensively explored, but these effects have not been examined in the context of MP contamination. To assess the impacts of legume straw and polyethylene microplastics on SOC fractions and carbon dioxide (CO2) and nitrous oxide (N2O) emissions, 7-month soil incubation experiments were performed. The results revealed that the inclusion of legume straw in soil considerably increased microbial SOC compared to the control. However, straw addition to MP-contaminated soil reduced microbial SOC compared to that in soil containing only straw. In contrast, the addition of straw to MP-contaminated soil elevated (+44%) the SOC mineral relative to the sole application of straw. Intriguingly, straw incorporation into MP-contaminated soil reduced microbial biomass carbon and nitrogen relative to soil containing only straw. Straw addition to MP-contaminated soil enhanced the nitrification activity and reduced the relative expression of AOBamoABC gene compared to sole straw-incorporated soil and the control. Greenhouse gas emissions were also modulated; for instance, straw incorporation into MP-contaminated soil reduced CO2 and N2O emissions by -11% and -46%, compared to straw incorporation alone. The urease and phosphatase activities were decreased (-58% and -12%) in the MP-polluted soil with straw incorporation compared with those in the soil in which only straw was applied. However, invertase and catalase activities were upregulated in the straw-incorporated soil contaminated with MPs. Straw addition in the MP-polluted soil considerably enhanced (+2%) the microbial community structure (indicated by PLFA) compared to the sole straw application. These results provide a comprehensive perspective on the role of legume straw incorporation in addressing MP pollution, showcasing its potential for sustainable agricultural practices in the face of evolving environmental challenges.

Biochar relieves the toxic effects of microplastics on the root-rhizosphere soil system by altering root expression profiles and microbial diversity and functions

The accumulation of microplastics in agricultural soil brings unexpected adverse effects on crop growth and soil quality, which is threatening the sustainability of agriculture. Biochar is an emerging soil amendment material of interest as it can remediate soil pollutants. However, the mechanisms underlying biochar alleviated the toxic effects of microplastics in crops and soil were largely unknown. Using a common economic crop, peanut as targeted species, the present study evaluated the plant physiologica and molecular response and rhizosphere microbiome when facing microplastic contamination and biochar amendment. Transcriptome and microbiome analyses were conducted on peanut root and rhizosphere soil treated with CK (no microplastic and no biochar addition), MP (1.5% polystyrene microplastic addition) and MB (1.5% polystyrene microplastic+2% peanut shell biochar addition). The results indicated that microplastics had inhibitory effects on plant root development and rhizosphere bacterial diversity and function. However, biochar application could significantly promote the expressions of key genes associated with antioxidant activities, lignin synthesis, nitrogen transport and energy metabolism to alleviate the reactive oxygen species stress, root structure damage, nutrient transport limitation, and energy metabolism inhibition induced by microplastic contamination on the root. In addition, the peanut rhizosphere microbiome results showed that biochar application could restore the diversity and richness of microbial communities inhibited by microplastic contamination and promote nutrient availability of rhizosphere soil by regulating the abundance of nitrogen cycling-related and organic matter decomposition-related microbial communities. Consequently, the application of biochar could enhance root development by promoting oxidative stress resistance, nitrogen transport and energy metabolism and benefit the rhizosphere microecological environment for root development, thereby improved the plant-soil system health of microplastic-contaminated agroecosystem.

Microplastic removal and management strategies for wastewater treatment plants

Discharging microplastics into the environment with treated wastewater is becoming a major concern around the world. Wastewater treatment plants (WWTPs) release microplastics into terrestrial and aquatic habitats, mostly from textile, laundry, and cosmetic industries. Despite extensive research on microplastics in the environment, their removal, and WWTP management strategies, highlighting their environmental effects, little is known about microplastics' fate and behaviour during various treatment processes. Microplastics interact with treatment technologies differently due to their diverse physical and chemical characteristics, resulting in varying removal efficiency. Microplastics removed from WWTPs may accumulate in soil and harm terrestrial ecosystems. Few studies have examined the cost, energy use, and trade-offs of large-scale implementation of modern treatment methods for the removal of microplastics. To safeguard aquatic and terrestrial habitats from microplastics' contamination, focused and efficient management techniques must bridge these knowledge gaps. This review summarizes microplastic detection, collection, removal and management strategies. A compilation of treatment process studies on microplastics' removal efficiency and their destiny and transit paths shows recent improvement. Bioremediation, membrane bioreactor (MBR), electrocoagulation, sol-gel technique, flotation, enhanced filtering, and AOPs are evaluated for microplastic removal. The fate and behaviour of microplastics in WWTPs suggest they may be secondary suppliers of microplastics to receiving ecosystems. Innovative microplastic removal strategies and technologies such as nanoparticles, microorganism-based remediation, and tertiary treatment raise issues. These new WWTP technologies are examined for feasibility, limitations, and implementation issues. Pretreatment modifies microplastic size, adsorption potential, and surface morphology to remove microplastics from WWTPs. Membrane bioreactors (MBR) can remove 99.9% of microplastics more efficiently than other approaches. MBR systems require membrane cleaning and fouling control, which raises operational and capital costs. To reduce MPs, plastic alternatives and strict controls, including microplastic waste transformation, should be prioritized. Microplastics must be controlled through monitoring policy execution and awareness.

Microplastics occurrence in commercial crab (Portunus segnis) from the western coast of India and pollution indices: First investigation and evidence

Microplastic (MP) pollution has increased drastically due to improper plastic waste management. The present study aimed to investigate the MPs contamination in the commercially important brachyuran crab Portunus segnis of Gujarat State, India. One hundred fifty crab specimens were collected from three principal fishing harbors in Gujarat. The collected specimens were analyzed for MP extraction using a previously documented protocol. The chemical composition of extracted MPs was assessed with ATR-FTIR. The average abundance of MPs contamination was recorded as 0.82 ± 0.58 MPs/g and 2.02 ± 1.48 MPs/individual. Findings of Contamination Factor (CF) revealed that study site Jakhau was identified as a low-contamination site, while Okha and Veraval were considered moderately contaminated. The H index has identified study sites Jakhau and Veraval as class IV risk categories, while study site Okha fell into the class V risk category. PRI value revealed the very high contamination of MPs in all the study sites. The guts were recorded as being more contaminated with MPs than the gills. The average abundance of MP contamination in males (0.77 ± 0.14 MPs/g in Jakhau, 1.19 ± 0.77 MPs/g in Okha, and 0.82 ± 0.43 MPs/g in Veraval) was recorded higher than in females (0.33 ± 0.11 MPs/g in Jakhau, 0.8 ± 0.49 MPs/g in Okha, and 0.75 ± 0.41 MPs/g in Veraval) in all the study sites. The average abundance of MP contamination varied significantly between males and females. Fibers were found dominantly in all study sites, followed by fragments, films, and foams. Black and blue-colored MPs with 1-2 mm sizes were found more abundantly. The chemical composition of the extracted MPs revealed polyethylene, nylon, polyurethane, and polystyrene as polymer compositions. Overall, the present study highlighted the MP contamination in commercially important crabs that can be used as a basis for further studies on ecotoxicology and seafood safety.

A study on managing plastic waste to tackle the worldwide plastic contamination and environmental remediation

Over the past 50 years, the emergence of plastic waste as one of the most urgent environmental problems in the world has given rise to several proposals to address the rising levels of contaminants associated with plastic debris. Worldwide plastic production has increased significantly over the last 70 years, reaching a record high of 359 million tonnes in 2020. China is currently the world's largest plastic producer, with a share of 17.5%. Of the total marine waste, microplastics account for 75%, while land-based pollution accounts for responsible for 80-90%, and ocean-based pollution 10-20% only in overall pollution problems. Even at small dosages (10 μg/mL), microplastics have been found to cause toxic effects on human and animal health. This review examines the sources of microplastic contamination, the prevalent reaches of microplastics, their impacts, and the remediation methods for microplastic contamination. This review explains the relationship between the community composition and the presence of microplastic particulate matter in aquatic ecosystems. The interaction between microplastics and emerging pollutants, including heavy metals, has been linked to enhanced toxicity. The review article provided a comprehensive overview of microplastic, including its fate, environmental toxicity, and possible remediation strategies. The results of our study are of great value as they illustrate a current perspective and provide an in-depth analysis of the current status of microplastics in development, their test requirements, and remediation technologies suitable for various environments.

Microplastic contamination in groundwater on a volcanic Jeju Island of Korea

Microplastic (MPs) contamination in groundwater has received massive attention since plastic waste has been released directly into the environment. This study investigates MPs contamination in groundwater on the Jeju volcanic Island, Korea. To the best of our knowledge, this is the first study to identify MPs in groundwater from volcanic islands. A total of 21 sites were sampled for groundwater wells and springs in July and September (2021). Sampling was performed without cross-contamination through quality assurance and quality control. The results showed that MPs abundance ranged from 0.006 to 0.192 particles/L in groundwater samples. Additionally, MPs were detected in deep groundwater wells where the groundwater level was 143 m below ground surface. Eight MPs polymer types, including polypropylene, polyethylene, polyethylene terephthalate, polyvinyl chloride, polystyrene, polyamide, acrylonitrile butadiene styrene, and polyurethane, were detected using Micro-Fourier Transform Infrared Spectroscopy (μ-FT-IR). Most of the detected MPs size ranged from 20 to 100 μm, accounting for 95% of the total. Fragments and fiber shaped MPs were detected, with the majority of them being fragmented in groundwater samples. The concentrations of MPs and major ions in groundwater showed a positive correlation. A negative correlation was observed between MPs concentration and topographic elevation (r = -0.59, p = 0.01). The source of MPs contamination is most likely attributed to agricultural activities, such as plastic mulching and greenhouses, which account for most of the land use in the study area. In this study, MPs entered the aquifer through the soil at the surface and seeped through cracks in fractured rock on basalt with sealed groundwater wells. This study takes 500 L of samples to prevent sample bias, reveal plastic contamination in groundwater, and indicating the characteristics and sources of contaminated plastics.

Spatiotemporal distribution and potential sources of atmospheric microplastic deposition in a semiarid urban environment of Northwest China

In this study, the spatiotemporal distribution of microplastic deposition was investigated through ordinary Kriging interpolation, and the potential sources of microplastic deposition were identified by using Hybrid Single-Particle Lagrangian Integrated Trajectory model. The results showed that the total deposition flux of microplastics ranged from 79.5 to 810.0 p/(m²·d). The shapes of microplastics could be divided into 4 shapes: fiber, fragment, film, and pellet. Seven polymer types of microplastics were identified, including polyamide (PA), polyethylene (PE), polyethylene terephthalate (PET), polymethyl methacrylate (PMMA), polypropylene (PP), polystyrene (PS), and polyvinyl chloride (PVC). Most microplastics were tiny and small sizes (≤ 500 μm) and colorless. Through model analysis and survey, microplastic deposition came from the study region, and the potential sources might be plastic products and wastes. The seasons with the highest and lowest total deposition flux were summer (535.5 p/(m²·d)) and winter (197.5 p/(m²·d)), respectively. The months of the highest and lowest total deposition flux were June 2021 (681.4 p/(m²·d)) and January 2022 (112.2 p/(m²·d)), respectively. Most fibers (PET, PA, PP) and fragments (PP) were distributed in populous areas such as commercial centers and residential areas. Abundant fragments (PET, PS, PE) and films (PE, PVC) were distributed around salvage stations. Almost all of the pellets (PE, PMMA) were found in the factory. Our results suggested that the temporal distribution of microplastic deposition was influenced by precipitation and mean temperature of air, and the spatial distribution of microplastic deposition was influenced by sources and population density.

Impact of microplastic pollution in terrestrial ecosystem on index and engineering properties of sandy soil: An experimental investigation

Sandy soils cover a major portion of various natural and managed ecosystems. Soil health plays a key role in achieving sustainable development goals 2, 3,11, 12, 13 and 15. The engineering properties of soil are crucial in determining the stability and safety of structures. The increasing microplastic contamination in the soil ecosystem creates a need to study the effect of terrestrial microplastic contamination on the strength and stability of soil and therefore on the index properties and engineering properties of the soil. The present paper investigates, the effects of varying concentrations (2 %,4 %,6 % (w/w)) of Low-density polyethylene (LDPE), Polyvinyl chloride (PVC), and High-density polyethylene (HDPE) microplastics on the index properties and engineering properties of sandy soil for varying observation days. The moisture content, specific gravity, shear strength, compaction characteristics and permeability are found to be significantly altered by changing the concentrations of microplastics but, insignificant changes are observed with respect to observation days. The shear strength value of non-contaminated sandy soil is 1.74 kg/cm² which reduces after 5th observation days as 0.85 kg/cm², 0.90 kg/cm², and 0.91 kg/cm² for 2 %, 4 %, and 6 % LDPE microplastic contamination respectively. Similar trends are observed for PVC and HDPE microplastic contamination. It is also observed that although the shear strength value decreases, the cohesion value increases for the microplastics-contaminated sandy soil. The coefficient of permeability for non-contaminated sample is 0.0004 m/s which reduces for 2 % LDPE microplastic contamination to 0.000319 m/s, for 4 % to 0.000217 m/s, and 6 % to 0.000208 m/s respectively. Similar trends of are observed for the PVC and HDPE microplastic contamination. The soil strength and structural stability are affected due to alterations in soil index and engineering properties. The paper provides detailed experimental evidence of the impact of microplastic pollution on index properties and engineering properties of sandy soil.

Microplastic as an invisible threat to the coral reefs: Sources, toxicity mechanisms, policy intervention, and the way forward

Microplastic (MP) pollution waste is a global macro problem, and research on MP contamination has been done in marine, freshwater, and terrestrial ecosystems. Preventing MP pollution from hurting them is essential to maintaining coral reefs' ecological and economic benefits. However, the public and scientific communities must pay more attention to MP research on the coral reef regions' distribution, effects, mechanisms, and policy evaluations. Therefore, this review summarizes the global MP distribution and source within the coral reefs. Current knowledge extends the impacts of MP on coral reefs, existing policy, and further recommendations to mitigate MPs contamination on corals are critically analyzed. Furthermore, mechanisms of MP on coral and human health are also highlighted to pinpoint research gaps and potential future studies. Given the escalating plastic usage and the prevalence of coral bleaching globally, there is a pressing need to prioritize research efforts on marine MPs that concentrate on critical coral reef areas. Such investigations should encompass an extensive and crucial understanding of the distribution, destiny, and effects of the MPs on human and coral health and the potential hazards of those MPs from an ecological viewpoint.

Are there plastic particles in my sugar? A pioneering study on the characterization of microplastics in commercial sugars and risk assessment

Although several studies are confirming the ubiquity of microplastics (MPs) in environments, our knowledge about their effects on human health is still very limited. Therefore, while we have not gathered definitive information on their consequences, studies that aim to identify the MPs sources constitute subsidies to better understand the various exposure pathways to these pollutants. Thus, we investigated the possible presence of MP-like particles in five brands of commercial sugars and two unpacked, unbranded, and unlabeled sugars (hereinafter referred to as "non-branded"), obtained from different supermarkets in Dhaka (Bangladesh). Surprisingly, MPs-like particles were identified in all analyzed samples and taken together, our data demonstrated similar variations (between branded and non-branded samples) in terms of number, size, shape, color, and polymer composition. The number of plastic particles/kg sugar was, on average, 343.7 ± 32.08 (mean ± SEM), having been observed a tendency for a higher frequency of MPs < 300 μm. Overall, microfibers and spherules were the most and the predominant colors of MPs (in general) were black, pink, blue, and brown. The FT-IR analysis confirmed the chemical nature of MPs (in branded and non-branded), having identified nine polymeric types (ABS, PCV, PET, EVA, CA, PTFE, HDPE, PC, and nylon), being ABS and PVC the most frequent. Furthermore, we estimate that sugar consumption in Dhaka City can cause the ingestion of millions of tons of MPs annually (2.4 to 25.6 tons) (with an average of 10.2 tons). Our study is the most comprehensive report on the MP's occurrence in sugar, confirming that the ingestion of this food constitutes an important route of human exposure to these micropollutants and, therefore, serves as a baseline for future assessments and useful for generating efficient strategies to control MPs.

Spatio-temporal contamination of microplastics in shellfish farming regions: A case study

The seasonal pattern of microplastics (MPs) contamination of the French littoral area of the Pertuis Charentais, one of the main French shellfish production regions, was assessed for the first time, between May 2019 and May 2020 at four different sites. The reference site was located at "Ile de Ré" and the other sites were located in the estuaries of the Sèvre Niortaise, Charente and Seudre rivers. Both blue mussels (Mytilus edulis) and Pacific oysters (Magallana gigas), that are considered sentinel species for the quality of the marine environment were analysed, along with sediment and seawater samples. MPs were extracted from each sample, counted, measured and sorted by colour and type. Micro-Raman spectroscopy was used to determine the proportion of confirmed MPs and the polymer types. The results showed that the contamination of mussels by fibres and fragments (1.9 ± 2.1 MPs/g ww) was significantly higher than for oysters (0.4 ± 0.4 MPs/g ww). Specifically, the contamination by fibres in both species was significantly greater than the contamination by fragments. Significant variations of MPs contamination were observed across the seasons and sites in bivalves, and depended on the species and the type of MPs (fibres or fragments). Mean concentrations of MPs measured in water and sediment were 0.007 MPs/L and 210 MPs/kg dw, respectively. Finally, blue was the dominant colour for fibres (79 %) and fragments (81 %). Blue fragments were mainly made of PS (70 %) followed by PC (18 %) and PP, PA or PLA (3 %) whereas blue fibres were mainly made of PA (80 %) followed by PET (13 %) or PP (7 %). This rare environmental case study of long-term chronic exposure of farming areas to MPs provides new knowledge on in situ variations of plastic fibres and fragments contamination throughout the seasons.

Quantitative assessment of microplastic in sandy beaches of Gujarat state, India

The present study was carried out to quantify microplastic prevalence among 20 sandy beaches on the Gujarat coast. Beaches were categorised into three different classes, viz. low-impacted sites, moderately impacted sites, and highly impacted sites based on anthropogenic pressure. Microplastic (MP) (≤ 5 mm) contamination on the beaches varied with an average of 1.4 MPs/kg to 26 MPs/kg sediment. Sutrapada site-1 and Porbandar showed the highest and lowest mean abundance of microplastics, respectively, among 20 selected beaches. Out of the total assessed microplastics, threads were the maximum (89.98%), followed by the films (4.75%), fragments (3.36%) and foam (1.89%). In terms of colour and size, different microplastics were recorded in this study. The chemical composition of microplastics was identified by ATR-FTIR as polypropylene (47.5%), polyethylene (26%), and polystyrene (25%). Tourism and fishing activities are the possible sources of higher microplastic contamination at highly impacted sites.

Composition and spatial distribution of floating plastic debris along the estuarine ecocline of a subtropical coastal lagoon in the Western Atlantic

With the objective of characterizing the composition and spatial distribution of plastic fragments in a subtropical lagoon system, five sample areas affected by various anthropogenic impacts were chosen in the southern part of the Estuarine Lagoon System in Laguna, Santa Catarina, Brazil. The total density of the floating meso- and microplastics encountered was 7.32/m³, with the greatest density in the access channel and external area of the lagoon. Plastic filament was the most abundant and mainly comprised polyester (PET), polypropylene (PP) and polyethylene (PE) from 0.05 to 0.71 mm². Fishing and urbanization were the main sources of the meso- and microplastics in the environment. This is the first study to evaluate contamination by meso- and microplastics in the southern part of the Estuarine Lagoon System and provides information about the nature and extent of contamination by plastics in this estuarine ecosystem.

Microplastics in an anadromous national fish, Hilsa shad Tenualosa ilisha from the Bay of Bengal, Bangladesh

Hilsa shad is one of the most important fisheries, contributing about 12.9% of the country's (Bangladesh) total fish production. There was no previous study on microplastic contamination of this important commercial fish. This study aims to identify, classify, and quantify microplastics (MPs) ingested by the national fish of Bangladesh, Hilsa shad, Tenualosa ilisha. A total of 287 MPs were recovered from the gastrointestinal tracts. All the fishes analyzed were contaminated with MPs. The mean (±SD) of the number of MPs was 19.13 ± 10.77 particles/fish, ranging from 7 to 51 particles/fish. Significant correlation was not found between the fish body length and MP abundance (rs = 0.287, p = 0.299), and between the fish body weight and MPs abundance (rs = 0.261, p = 0.347). The most dominant color was transparent (30%), followed by gray and black, contributing to 26% and 23%, respectively. The maximum number of MPs accounted for in the 300-1500 μm size class where fiber was the most dominant (50%) shape of observed MPs. These results provide a baseline of MP contamination in seafood from Bangladesh that should be useful for future monitoring efforts. The present study is the first research on MP contamination of Hilsa shad.

Spatio-seasonal microplastics distribution along a shallow coastal lagoon ecocline within a marine conservation unit

The aim of our study is to estimate the abundance and sources of floating microplastics (MPs) along a coastal lagoon ecocline in a marine conservation unit (MCU) for implementing effective prevention and mitigation actions in South Brazil. MPs were sampled monthly, and the abundance and size were determined for hard solids, soft plastic, plastic filaments, and paint fragments. Attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) analysis was performed, and the MPs were classified as polyethylene, polyester, polypropylene, polybutadiene, and polystyrene. Downstream areas (outside of the MCU) showed high levels of MPs, during the winter, due to low precipitation and the predominance of S/SE winds. During summer, precipitation increases, and MPs are exported with surface runoff, resulting in lower level of MPs. Outside MCU areas, a high concentration of tourism houses, commercials, and artisanal fisheries were observed, which could contribute to all types of plastic debris found in our study.

Ingestion of microplastics by the estuarine polychaete, Namalycastis sp. in the Setiu Wetlands, Malaysia

In this study, the ingestion of microplastics by the deposit-feeding polychaete Namalycastis sp. in the estuarine area of the Setiu Wetlands, Malaysia was confirmed. Samples were collected from six stations, covering the wetland from the south to the north, bimonthly between November 2016 and November 2017. Microplastics were extracted from polychaete samples following digestion in an alkaline solution (10 M NaOH). They were identified by physical characteristics (i.e., shape and color under dissecting microscope and scanning electron microscope), and chemical analysis using a LUMOS Fourier Transform Infrared Microscope (μ-FTIR). A total of 3277 pieces were identified, which were dominated by filaments (99.79%) and with the majority transparent in color (84.71%). Most of the microplastics identified were polypropylene (PP) followed by polyamide (PA) based on their main peak in the of μ-FTIR spectrum. Principal component analysis demonstrated the dominance of microplastics at stations 3 and 4 of the sampling area, probably because of the influx from the open sea and from aquaculture. The findings of this research provide baseline information on microplastics ingested by benthic organisms and their fate in the estuarine food web.

High levels of microplastic ingestion by commercial, planktivorous Alburnus tarichi in Lake Van, Turkey

Microplastic pollution of inland environments has been receiving increased publicity over the last few years. For the first time, this study reports on the presence of microplastics (0.1 mm to <5 mm) in the gastrointestinal tracts of Alburnus tarichi in Lake Van from January to April 2020. In total, 101 fishes were obtained from Citoren, Edremit, Gevas and Dagonu fisheries regions. A total of 3338 pieces of plastic, ranging from 8 to 124 samples per fish with averaging 34 ± 13 MPs/individual, were extracted from gastrointestinal tracts of fish. The majority of the ingested particles consisted of fibres (74%), and blue coloured material was the most consumed microplastic. The polymers identified by Fourier Transform Infrared Spectroscopy (FTIR) were polyethylene and polypropylene. Consequently, this study suggested that the vast majority of A. tarichi were contaminated with microplastics and showed higher abundance in comparison with other worldwide studies so far.

First evidence of microplastic contamination in the freshwater of Lake Guaíba, Porto Alegre, Brazil

The ubiquitous presence of microplastics in the aquatic environment has raised concern about their potential impacts on and risks to the biota. While the presence of microplastics in a marine environment has been well studied, the impact of microplastic contamination in freshwater bodies is understudied. In the present study, baseline data about contamination with microplastics in Lake Guaíba in southern Brazil are presented. The abundance, distribution, and composition of microplastics in the surface of this freshwater body were investigated, and these parameters were correlated with population density, land occupation, wind, and geohydrologic processes. The samples were collected with a manta net (60 μm mesh size). Microplastics were found in all the samples, with an average of 11.9 ± 0.6 to 61.2 ± 6.1 items m^-3, which indicates the widespread contamination of the lake with plastic particles. The most frequent microplastic morphology was the fragment type in the size range of 100 to 250 μm, and the predominant colours were white/transparent and red. Measurement uncertainty of the visual microplastic counts showed that black colour microplastics is more susceptible to be mistaken, which might lead to an underestimation and/or overestimation of the total number of microplastics. Polypropylene and polyethylene together comprised most of the polymer types (98%). Micro-Fourier transform infrared (micro-FTIR) spectroscopy analyses showed that 58% of the analysed polymers were highly oxidised, indicating long residence of this particles in the water. In addition, our data show that the distribution of microplastics is strongly influenced by the geohydrological characteristics of the lake. Therefore, this research may provide information for further investigations of microplastic distribution in Lake Guaíba and can serve as a base to improve the regulations regarding waste management to effectively reduce microplastic pollution in freshwater systems. Additionally, the measurement uncertainty showed that black microplastics are more susceptible to variations in their measurements.

Abundance and distribution characteristics of microplastic in plateau cultivated land of Yunnan Province, China

Microplastic pollution in cultivated soil has received increasing attention recently. There may be more serious microplastic abundance but little research has been done in cultivated soil in plateau areas. To survey the pollution characteristics of microplastics in inland cultivated soil, 100 soil samples collected from 10 counties of Yunnan Province were investigated through density separation and microscopic examination. The research results showed that microplastic abundance was in the range of 0.9 × 10³ to 40.8 × 10³ particles (kg Ds)^-1 with average abundance of 9.8 × 10³ particles (kg Ds)^-1. Moreover, compared with other studies on sediments, it was found that microplastic abundance in inland soil was one order of magnitude higher than that in offshore sediments. The use of plastic mulch and its long-term residue in cultivated soil was an important reason for microplastic pollution. In this survey, various morphologies of microplastics existed, including fragment (78.3%), transparent/translucency (49.7%), and micro-size microplastics (< 500 μm) (89.3%). And the microplastic morphologies occurred in different degrees of aging phenomenon under the influence of the environment factors such as ultraviolet radiation. The findings provided the pollution status of microplastics in cultivated soil, and more attention should be paid to inland soil microplastic pollution. Grapical abstract.

Microplastics contamination in the soil from Urban Landfill site, Dhaka, Bangladesh

Microplastics (MP) pollution has become a matter of global concern because of its several deleterious effects on environmental health, especially on the terrestrial environment. The evidence of MP contamination in terrestrial environment is less explored compared to aquatic bodies. However, in Bangladesh despite having high possibility of MP contamination, there is lacking of available research-based evidence. Urban areas soil is subjected to act as a major environmental reservoir for MPs. Thus, this study was carried out to investigate the presence of MP contamination in constructed landfill sites near Dhaka city, Bangladesh. Ten unmixed soil samples were collected from the Aminbazar Sanitary landfill sites, from that thirty replicated samples were investigated via Fourier Transform Infrared Spectroscopy (FT-IR) analysis and Stereomicroscope. The range of physicochemical parameters were found in the soil samples as follows: moisture content; 15.84%-56.54%; soil pH; 5.76-6.02, electric conductivity; 0.1 μs/cm - 2.43 μs/cm, alkalinity; 6.7 ± 1.528-14.33 ± 0.577, TOC; 0.18% ± 0.02-1.09 ± 0.03. Among the ten samples, 3 samples were identified to have the presence of MP in the form of Low density polyethylene (LDPE), High density polyethylene (HDPE), and Cellulose acetate (CA) respectively. The detection limit ranged from 1 - 2000 μm. Hence, the results show that the procurement and discharge of MPs in the landfills is an overlong process. The results of this study provide an initial evidence and affirm that landfill can be a potential source of MPs. This study indicates that MPs are comparatively overlong outcome of human induced activities which can significantly cause changes in terrestrial ecosystems.

The impact of tourism on marine litter pollution on Santa Marta beaches, Colombian Caribbean

Tourism is an important socioeconomic activity in coastal communities, which deteriorates marine-coastal ecosystem quality when poorly managed, increasing litter pollution on beaches during the main tourist seasons. This study aims to assess the tourism impact on litter pollution on eleven Santa Marta beaches, Colombian Caribbean. During high and low tourist seasons, people on the beaches were counted, macrolitter and microplastics were sampled, and perception surveys about litter on beaches were conducted. During the high tourist season, the number of people and macrolitter pollution increased, compared to the low tourist season. Plastics accounted for 30%-77% of macrolitter and microplastics ranged from 1 to 355 items/m². Respondents identified tourism as a main litter source and plastics as the most common litter type. All assessed beaches are impacted by tourism causing litter pollution, therefore, stronger controls, educational, and awareness strategies are needed to reduce litter pollution and prevent ecological and socioeconomic impacts.

Factors influencing the spatial and temporal distribution of microplastics at the sea surface - A year-long monitoring case study from the urban Kiel Fjord, southwest Baltic Sea

Microplastics are ubiquitous to most marine environments worldwide, and their management has become one of the major challenges facing stakeholders. Here we monitored monthly, between March 2018 and March 2019, the abundance of microplastics (0.3-18.2 mm) at the sea surface within the Kiel Fjord, southwest Baltic Sea. Microplastics were sampled at eight locations, inside and outside the fjord, near potential source of microplastics, such as the outlets of storm drains or the Kiel-Bülk wastewater treatment plant, the Schwentine River mouth and the entrance of the Kiel Canal. Weather (wind, precipitations) and seawater (salinity, temperature) parameters were compared to the spatiotemporal distribution of the microplastics. We found an overall stable, and low (0.04 particles/m³), microplastic load within the Kiel Fjord compared to other urban areas worldwide with comparable population densities. No relationship was found between the microplastic abundance and the environmental factors, but the few samples that yielded unusually high amount of microplastics were all preceded by rainfall and snow/ice melt. During such events, vast amounts of water, potentially contaminated with microplastics, were released into the fjord via the storm drainage system. The microplastic abundances at the wastewater plant outflow were among the lowest of our survey, likely thanks to an efficient filtering system. The results of this study highlight the importance to repeat microplastic samplings over time and space to determine with confidence baseline microplastic abundance and to detect unusual acute contamination, especially during snow and ice melting. Overall, the microplastic abundance within the Kiel Fjord was low, probably thanks to efficient waste management on land. However, improvements are still needed to filter millimetre-sized particles within the storm drainage system, which is likely a major source of microplastics into the marine environment.

Evaluation of microplastics in beach sediments along the coast of Dubai, UAE

Microplastic contamination in beach sediments along coast of Dubai is un-documented. In this study, microplastic contamination in beach sediments collected from the wrack lines of 16 beaches in Dubai was evaluated. Five samples were collected from each beach along a 100 m stretch using a 0.5 m by 0.5 m, quadrant. The number, color, and shape of microplastics were documented. The polymer types of large fibers and strings were identified through FT-IR analysis. 480 microplastics from each of the 16 beaches were selected to detect heavy metals using XRF analysis. The results showed that the average weight of microplastic is 0.33 mg per gram of dry sediment (or 953 mg·m^-2) and the number of microplastic is 59.71 items per kg of dry sediment (or 165 items·m^-2). Blue and fibrous microplastics were dominant. Polyethylene strings and fibers were abundantly found. 13 heavy metals were identified of which five are priority pollutants.

Low prevalence of microplastic contamination in planktivorous fish species from the southeast Pacific Ocean

The gut contents of 292 planktivorous fish, from four families (Atherinopsidae, Clupeidae, Engraulidae and Scombridae) and seven species, captured along the coast of the southeast Pacific, were examined for microplastic contamination. Only a small fraction of all studied fish (2.1%; 6 individuals) contained microplastic particles in their digestive tract. Microplastics found were degraded hard fragments and threads, ranging from 1.1 to 4.9 (3.8±SD 2.4) mm in length, and of various colours, which suggests that the planktivorous fish species examined herein did not capture microplastics on the basis of their colour. The low prevalence of microplastic contamination in planktivorous fishes found in this study suggests that the risk of accidental ingestion by these species might be limited in the coastal upwelled waters of the southeast Pacific, perhaps due to small human population and highly dynamic oceanographic processes.

Amberstripe scad Decapterus muroadsi (Carangidae) fish ingest blue microplastics resembling their copepod prey along the coast of Rapa Nui (Easter Island) in the South Pacific subtropical gyre

An increasing number of studies have described the presence of microplastics (≤5mm) in many different fish species, raising ecological concerns. The factors influencing the ingestion of microplastics by fish remain unclear despite their importance to a better understanding of the routes of microplastics through marine food webs. Here, we compare microplastics and planktonic organisms in surface waters and as food items of 20 Amberstripe scads (Decapterus muroadsi) captured along the coast of Rapa Nui (Easter Island) to assess the hypothesis that fish ingest microplastics resembling their natural prey. Sixteen (80%) of the scad had ingested one to five microplastics, mainly blue polyethylene fragments that were similar in colour and size to blue copepod species consumed by the same fish. These results suggest that planktivorous fish, as a consequence of their feeding behaviour as visual predators, are directly exposed to floating microplastics. This threat may be exacerbated in the clear oceanic waters of the subtropical gyres, where anthropogenic litter accumulates in great quantity. Our study highlights the menace of microplastic contamination on the integrity of fragile remote ecosystems and the urgent need for efficient plastic waste management.