Sources and sinks of microplastics in Canadian Lake Ontario nearshore, tributary and beach sediments

Wind driven transport of macroplastic debris in a large urban harbour measured by GPS-tracked drifters

The transport pathways of floating plastic debris in Toronto Harbour, Ontario, Canada, were assessed using a series of GPS-tracked drifter bottles. The drifter trajectories were largely controlled by winds, and they could traverse the 2 km wide harbour within a day. The average ratio of drifter speed to wind speed (the wind factor) is consistent with values of 2-5 % used in modelling dispersion of marine debris. However, significant variability in wind factors meant some drifters travelled 2-5 times faster than expected in small waterbodies (Toronto Harbour), and as much as 7 times faster in large waterbodies (Lake Ontario). Importantly, based on our calculated wind factor equations and the coincident accumulation of our drifters with real plastic debris, we can justify the use of wind factors when studying plastic debris transport. Most (75 %) of the drifters that were released in the harbour, stayed within the harbour, accumulating downwind. However, 14 of all 66 drifters escaped Toronto Harbour, where ∼70 % escaped through the West Gap while ∼30 % escaped via the Outer Harbour. One drifter made a 290 km journey across Lake Ontario in a period of 14 days, demonstrating that Toronto is a potential source of plastic debris throughout Lake Ontario.

Evaluating the role of urban green infrastructure in combating traffic-related microplastic pollution

As cities grapple with the invisible threat of airborne microplastics (MPs), non-exhaust emissions, especially traffic-related MPs, contribute significantly to urban air pollution. While emission regulations have reduced exhaust pollutants, non-exhaust sources remain a significant challenge. Urban green infrastructure (UGI), valued for aesthetic and ecological functions, remains underexplored for MP mitigation. This study assesses the role of a Thuja occidentalis hedge in Kaunas, Lithuania, as a natural barrier against traffic-related MPs. Over a four-month seasonal campaign, passive deposition sampling was conducted at four distances from the street, with additional sampling in the hedge's absence for an experimental-control comparison. Optical microscopy revealed distinct size and shape distributions, while μ-FTIR spectroscopy confirmed dominant polymer compositions: PE (69.05 %) in spring, PIR (35.96 %) in winter, and ACRs (28.52 %) in summer. The highest average fragment concentration occurred in spring (98.25 %), while fibers peaked in winter (12.75 %). Black was dominant year-round, with the highest average in spring (55.35 %), followed by white in winter (42.16 %) and brown in spring (26.98 %). MPs in the 50-100 μm range were most abundant, reaching 55.26 % in spring. A similar trend appeared in vertical MP distribution. The most pronounced difference was noticed at (+1 m) behind the hedge, where MP concentration was 4.59 particles cm-2 day-1, significantly lower than 9.2 particles cm-2 day-1 in the control. The hedge showed peak removal efficiencies in summer (64.5 % total MPs, 64.3 % fragments, 71.4 % fibers). The 50-100 μm range exhibited the highest efficiency, averaging 67.25 % with a seasonal high of 94.24 % in spring. Strong Mantel (rm) and Pearson's (r) correlations of very small MPs (<20 μm) at -1 m suggest a significant influence from tire wear, brake wear, and road dust resuspension. This study highlights Thuja hedge as an active defender against MP pollution, advocating for its strategic integration into urban design to enhance public health protection.

Preliminary investigation of the spatio-seasonal distribution of microplastics in the surface water of River Benue, North Central Nigeria

Rivers are critical pathways for microplastic (MP) pollution, yet data remain limited on MP presence in Nigeria's freshwater systems. This study presents the first comprehensive assessment of MP occurrence and associated risks in the River Benue, one of Nigeria's most important rivers. Surface water samples were collected in September 2023 (rainy season) and January 2024 (dry season), pre-treated with NaCl and H₂O₂ for density separation and wet peroxide oxidation, and analysed using FTIR spectroscopy and SEM-EDS. MP abundance was higher along the southern bank, ranging from 0 to 11 items L-1 in the dry season and 0 to 9 items L-1 in the rainy season. The lower rainy-season concentrations were attributed to improved hydraulic conditions, which enhanced dilution and downstream transport. Particle sizes ranged from 0.5 to 5 mm, with the 1.5-3 mm fraction being most abundant, raising concerns due to their bioavailability. Risk assessment revealed contamination factors of 2-22 and pollution load indices of 2-4.69, indicating sites with moderate to elevated risks. The PLIzone (3.23) confirmed severe pollution across the river, potentially warranting remediation. MP distribution patterns are strongly associated with anthropogenic activities, including commerce, transportation, and waste disposal. This study provides crucial baseline data on MP pollution in River Benue and supports the development of targeted management strategies. For a more comprehensive understanding, future investigations should explore the collection of larger sample volumes and asses contamination in the sediments and biota. These findings contribute to global efforts in understanding freshwater MP pollution, particularly in understudied tropical river systems.

Microplastic distribution in the surface water and potential fish uptake in an oligotrophic lake (Lake Mainit, Philippines)

Analyzing microplastic distribution patterns in freshwater ecosystems provides critical insights into pollution sources and accumulation zones, contributing to ecosystem health and functioning. Here, the surface water of Lake Mainit, an oligotrophic body of water in the Philippines, and the potential ingestion by Glossogobius giuris (15), a local fish species inhabiting the lake, were investigated. The surface water samples collected in ten sampling sites revealed an average microplastic concentration of 313.33 ± 252.11 particles/m3, with elevated levels in the northern part of the lake, likely due to adjacent industrial and agricultural activities. Fibers were the predominant microplastic morphology (58 %), with polyamide (28 %) as the most common polymer found in the surface water, suggesting primary sources from textiles and household waste. Size analysis showed that particles under 100 μm in size were most abundant, posing increased ingestion risks for aquatic organisms. All examined fish samples contained microplastics, averaging 0.7 particles per fish, primarily from the smallest particle class, indicating a potential risk of bioaccumulation. Risk assessment using the Polymer Hazard Index (PHI) and Pollution Load Index (PLI) indicated that polyvinyl chloride (PVC) and polyamide (PA) pose moderate to high pollution risks due to their persistence and toxicity potential. The PERI value for Lake Mainit was 34.63, classifying it as a minor risk. While current contamination levels are low, continued monitoring is essential to prevent future ecological risks. These results highlight the ecological threat of microplastics in Lake Mainit, with implications for biodiversity and human health, as the lake is an important local food source. To mitigate these risks, stricter pollution control, enhanced waste management, and public awareness initiatives are recommended. This study presents foundational data on microplastic pollution in an oligotrophic Philippine lake, emphasizing the need for further research to support protective management strategies.

Comprehensive analysis of microplastics in water, sediment and fish from a large recreational lake

While global attention has primarily focused on microplastics (MPs) in marine ecosystems, the issue of MP pollution in recreational lakes has received relatively little attention. In this study, the occurrence, spatial and seasonal distribution and characteristics of microplastics (MPs) were investigated for the first time in Lake Hazar (Türkiye), an important recreational lake. Water, sediment and fish (Capoeta umbla) were sampled from the lake in the winter and summer of 2020. Thereafter, the MPs were extracted from the samples using the density separation method. Their abundance, shape, color, and size were determined microscopically, while the polymer types were analyzed using ATR-FTIR. The MPs were detected in all surface water and sediment samples, while they were detected in the gastrointestinal tracts of 28 (35 %) out of 80 fish samples. The abundance of MPs was 74-1091 items/m3 for the surface water, 88-213 items/kg (ww) for sediments and 0-5 items/fish for C. umbla, respectively. The MP concentrations in water samples from the shore sites were found to be significantly higher than those in limnetic sites (p < 0.05). The most common MP shapes, sizes and colors were fragments, <0.5 mm and white/transparent, respectively. Polyethylene and polypropylene were the most common polymer types, indicating that recreational activities and fishing activities may be the main sources of MPs in the lake. The Pollution Load Index results indicated that MP pollution in the lake's water and sediments was at a moderate level.

Riverine microplastics in the Mount Everest region affected by glacier meltwater

Understanding the distribution and drivers of microplastics (MPs) in remote and sensitive environments is essential for assessing their ecological impacts and devising mitigation strategies. This study investigates the distribution and characteristics of MPs in streams and sediments of the Mt. Everest region. Results show that microplastic (MP) abundance during the non-monsoon season was 2-4 times higher than in the monsoon season. MPs were predominantly fragments, composed of specific polymer types (PA, PET), and fell within the 10-30 µm size range. An ecological risk assessment was conducted to better evaluate MP pollution in the Mt. Everest region. The study found that recharge sources of streams influenced MP distribution, with streams receiving non-glacial recharge exhibiting higher MP concentrations during the monsoon season, likely due to the dilution effect of glacier meltwater. Principal component analysis highlighted correlations between MP abundance and environmental factors such as wind speed, dissolved oxygen, stream order, and elevation. These findings advance our understanding of MP pollution dynamics in high-altitude streams, establish a foundation for evaluating their ecological impacts, and offer valuable insights for developing mitigation strategies. This study provides a critical reference for further exploring MP contamination in high-elevation ecosystems and addressing its challenges.

Microplastic contamination in sediments: Analytical techniques and case-based evaluations

Microplastics (MPs) pollution in sediments has gained critical attention due to its pervasive presence and potential ecological risks. This review synthesizes the latest advancements in analytical techniques, providing a comprehensive overview of separation and identification methods tailored to complex sedimentary matrices. Density-based approaches, such as ZnCl2 or NaI solutions, and enzymatic digestions are increasingly refined to isolate MPs of varying sizes, yet discrepancies in mesh sizes, reagent concentrations, and digestion protocols continue to complicate cross-study comparisons. Meanwhile, cutting-edge spectroscopic tools-μFTIR, Raman imaging, thermal analyses-have greatly enhanced polymer identification down to the tens-of-micrometers scale. Case studies spanning urban estuaries to remote deep-sea basins underscore the pervasive nature of MPs worldwide, with fibers and fragments frequently dominating sediment samples. Factors such as polymer density, hydrodynamics, and biofouling contribute to the diverse distribution patterns, revealing that even ostensibly pristine environments are not exempt from contamination. Although the precise ecological and toxicological consequences of long-term sediment-bound MPs remain partly unclear, growing evidence points to intricate interactions with co-occurring contaminants and potential trophic transfer. To address these knowledge gaps, this review emphasizes the urgent need for methodological standardization and collaborative initiatives, particularly for emerging challenges like nanoplastic detection. By integrating robust sampling approaches, advanced analytical tools, and interdisciplinary research, scientists and policymakers can more accurately map and mitigate the impacts of sediment-associated MPs on aquatic ecosystems.

First evidence of microplastics in surface water of urban waterbodies in Bhopal city, India- abundance and their characteristics

The present study focuses on the microplastics (MPs) abundance including identification and quantification in six major waterbodies of Bhopal city. Using the combined sampling method of bulk and volume reduced sampling the samples are collected from 19 different locations in winter, summer and monsoon weather for understanding the seasonal impact. MPs particles have been observed in the surface waters of all the water bodies of the Bhopal city across all seasons. The overall and average maximum MPs has been observed in Shahpura Lake near children's park and fishing area with overall abundance (SH2-1640 ± 162.69 particles/m3) and average abundance (SH2-1410 ± 162.69 particles/m3) during the monsoon of 2022. The least polluted waterbody is Kerwa dam having overall abundance of 510 ± 43.20 particles/m3 and average abundance of 570 ± 43.20 particles/m3 which was observed in summer of 2022. The identification by FTIR showed that the nylon and polypropylene are the most abundant types of polymers in all the locations. Statistical analysis shows that there is strong positive correlation in between the MPs abundance in different seasons. With all the above studies it can be concluded that MPs abundance in freshwater is increasing with the passage of time which is having adverse effect on the surrounding environment.

Microplastics inhibit lead binding to sediment components: Influence of surface functional groups and charge environment

The coexistence of heavy metals and microplastics in sediments is well recognized, yet the interactions within ternary systems remain underexplored, and comprehensive studies addressing the diverse sequences of sediment-microplastic-heavy metal coexistence are lacking. In this study, we systematically investigated the interactions among lead (Pb), polystyrene (PS) microplastics, and sediments (using goethite (Goe) and goethite-humic acid composite (GH) as examples) under different coexistence orders. The presence of PS significantly inhibited Pb adsorption by both Goe and GH. For Goe, adsorption kinetics and hydrochemical condition effects showed that PS reduced the electrostatic repulsion between Goe and Pb, leading to a fourfold increase in the mass transfer rate of Pb to the Goe surface. However, Pb 4f deconvolution indicated competition between PS and Pb for hydroxyl groups on Goe, resulting in a 7.4% reduction in Pb adsorption. In the GH system, hydrophobic interactions and coordination complexes between PS and humic acid on GH inhibited the electrostatic adsorption and mass transfer processes between Pb and GH. Pb adsorption behavior and changes in Pb-O content under different coexistence orders further verified that competition between PS and Pb for carboxyl and hydroxyl groups on GH led to a 28.0% reduction in Pb adsorption. This study highlights the inhibitory effect of PS on Pb adsorption by Goe and GH, providing a theoretical basis for understanding the migration and transformation patterns of microplastics and heavy metals in sediments.

Impact of Heterosigma akashiwo on the environmental behavior of microplastics: Aggregation, sinking, and resuspension dynamics

Aggregation processes of microalgae have significant effects on the vertical distribution of microplastics (MPs) in the marine environment. This study explored how the harmful microalga Heterosigma akashiwo affects the aggregation and sinking characteristics of four types of MPs: low and high-density polyethylene (PE) spheres, and small and large polypropylene (PP) fragments. The aggregation of MPs was primarily driven by extracellular polymeric substances (EPS) rather than direct attachment to the cells, contributing to their sinking. The sinking of low-density PE spheres followed a logistic function, saturating at 28 % with a half-saturation time of 9 days. In contrast, small PP fragments sank minimally (under 2 %) and large PP fragments showed almost no sinking, indicating the varying impacts of MP density and size. The sinking velocity of the MP aggregates was significantly lower for low-density PE spheres (0.63 mm∙s-1) than for high-density PE spheres (0.81 mm∙s-1), despite no significant differences in aggregate size or MP particle number. This result may suggest that low-density MPs could potentially affect marine carbon cycle. Furthermore, no clear evidence was found for the resuspension of the settled aggregates due to bacterial decomposition under dark and cold conditions. As the first experimental study to explore the aggregation, sinking, and resuspension of different MPs in the presence of H. akashiwo, these findings, when integrated with field observations and modeling studies, provide valuable insights for predicting MP distribution in marine environments.

Microplastic pollution in surface waters of urban canals in a highly urbanized city (Dunkirk, Northern France): influence of dry and wet periods on discharge to the sea

Microplastic (MP) pollution is a growing environmental concern, with urban waterways constituting critical pathways for transporting MPs into marine ecosystems. This study investigated the distribution, abundance, diversity, and flux of MPs in six urban canals influenced by urban and industrial activities in the city of Dunkirk, during dry and wet (rainy) periods. Plastic abundance was higher during the wet period (18.25 ± 22.16 particles/m3) compared to the dry period (8.14 ± 7.76 particles/m3), reflecting increased inputs from surface runoff and stormwater discharge. Spatial trends revealed distinct site-specific patterns, with the most urbanized sites (S1 and S6) exhibiting the highest abundances. Fibers were the dominant type accounting for over 75% of particles at all sites. PET was the main polymer in urban sites, while PE and PP were more prevalent in industrial zones. The estimated annual flux of MP at the outlet ranged from 19.21 × 106 ± 26.12 × 105 particles/year/m3 (dry period) to 23.97 × 107 ± 19.41 × 106 particles/year/m3 (wet period), revealing the significant contributions of urban canals to coastal pollution. These results highlight the need for improved source control and stormwater management to better assess and mitigate MP pollution in urban aquatic systems.

Remediation of Micro- and Nanoplastics by Membrane Technologies

Micro- and nanoplastics (NPs) cannot be completely removed from water/wastewater in conventional wastewater treatment plants (WWTPs) and drinking water treatment plants (DWTPs). According to the literature analysis, membrane processes, one of the advanced treatment technologies, are the most effective and promising technologies for the removal of microplastics (MPs) from water and wastewater. In this article, firstly, the properties of MPs commonly found in water and wastewater treatment and their removal efficiencies are briefly reviewed. In addition, research on the use of microfiltration (MF), ultrafiltration (UF), nanofiltration (NF), reverse osmosis (RO), and membrane bioreactors (MBR) for the remediation of MPs and NPs from water/wastewater is reviewed, and the advantages/disadvantages of each removal method are discussed. Membrane filtration is also compared with other methods used to remove MPs. Furthermore, the problem of membrane fouling by MPs during filtration and the potential for MPs to be released from the polymeric membrane structure are discussed. Finally, based on the literature survey, the current status and gaps in research on MPs removal by membrane technologies are identified, and recommendations for further research are made.

Concentrations, characteristics, and human health exposure assessment of microplastics and heavy metals in freshwater fish in a potable water supply reservoire

Microplastic pollution in the environment is a global concern because it exposes the ecosystem and biota to microplastics and other contaminants that adsorp to their surfaces. Fish are regularly consumed by humans, exposing people to microplastics through their consumption. In this study, we investigated microplastics and heavy metals in catfish (Clarias gariepinus) and tilapia (Oreochromis niloticus) in a portable water supply reservoir in Ghana. We quantified microplastics (MPs) and polymer composition in the guts and muscles of the fish using microscopic identification and Fourier Transform Infrared Spectroscopy (FTIR). The Atomic Absorption Spectroscopy (AAS) was used to quantified the levels of zinc (Zn), copper (Cu), and lead (Pb) in the muscles and gills. The results indicated that the mean number of MPs in the guts for tilapia and catfish were 9.17 ± 1.47 MPs/individual and 7.655 ± 0.93 MPs/individual respectively. The mean number of MPs in the muscles for tilapia and catfish were 0.86 ± 0.41MPs/g and 1.21 ± 0.61MPs/g respectively. In terms of abundance, fibers were the most common type of microplastic in both species, accounting for 92% in tilapia and 76.5% in catfish. The identified polymers were polyethylene (PE), polypropylene (PP), polystyrene (PS), polyester (PES), and cellophane (CP). PE was the most abundant polymer found in the fish, while CP was the least abundant, accounting for 40% and 8%, respectively. The exposure assessment suggests that consuming catfish exposes people to more microplastics than consuming tilapia. Heavy metals were found to accumulate more in the gills than in the muscles of the fish. The heavy metal levels in the muscles were higher in tilapia than in the catfish, however, the levels of metals detected in both species were within recommended limits, posing no risk to consumers. For tilapia, the concentrations of Zn, Pb, and Cu in the gills were 24.59 ± 1.88 mg/kg, 1.99 ± 0.28 mg/kg, and 1.51 ± 0.12 mg/kg respectively. The concentrations of Zn, Pb and Cu in the muscles of tilapia were 10.67 ± 2.09 mg/kg, 0.31 ± 0.06 mg/kg and 0.18 ± 0.04 mg/kg respectively. The concentrations of Zn, Cu and Pb in the gills of catfish were 8.08 ± 1.31 mg/kg, 1.38 ± 0.14 mg/kg, and 1.18 ± 0.15 mg/kg respectively. In the muscles of catfish, the concentrations of Pb and Cu were below detection, and the concentration of Zn was 3.51 ± 1.39 mg/kg. The study also showed a moderate positive relationship between lead (Pb) levels in gills and muscles and microplastics in the muscle of tilapia. Overall, the study shows the occurrence of MPs and heavy metals in both species, with higher heavy metal concentrations in the gills than in the muscles. The findings suggest that microplastics could potentially act as vectors for heavy metals in fish.

Seasonal variations and risk assessment of microplastic contamination in agricultural soil and associated macroinvertebrates in Egypt

Contamination by microplastics (MPs) has the potential to rank among the world's most significant environmental issues. Despite the fact that MP contamination is a global problem, little is known about the time variation of MPs in agricultural soil and its faunal communities which represent a key role to risk assessment. This study represents a first field investigation regarding the MP concentrations in agricultural ecosystem in Egypt. Our study investigates the seasonal fluctuations of MPs in soil and its common fauna in a citrus orchard (Citrus sinensis) in Egypt's Sohag Governorate. Moreover, this work aimed to identify how feeding strategies and body size of the selected fauna affect the no. of MPs ingested. The greatest mean concentration of MPs in soil was observed in summer (664 ± 90.20 items/kg) dry weight. However the lowest was recorded in autumn (354 ± 70.92 items/kg). Aporrectodea caliginosa (earthworms) was more contaminated with MPs (6.84 ± 2.5 item/individual annually) than Anisolabis maritima (earwigs) (2.06 ± 0.86 item/individual annually). When comparing between taxa without considering the size of the organisms, earwigs showed higher MPs concentrations (ranged from 117.93 ± 5.23 to 244.38 ± 4.57 items/gm wet weight) than the earthworms (ranged from 25.62 ± 2.43 to 51.66 ± 4.05 items/gm wet weight). Our results found that blue and red colors were the predominant colors in the soil and the selected fauna. Also, polyester fibers (PES) were the most popular type of microplastics, followed by fractions of polyethylene (PE) and polypropylene (PP). Interestingly, the reduction in the MP particles in the present taxa was observed compared to those in the soil. Pollution load index (PLI) value varied across seasons, with the lowest recorded in autumn due to reduced MPs abundance. The Hazard (H) index indicates a moderate risk (level III) due to high polyester abundance and a low hazard score (4) across all seasons. Our results represent a starting point for further studies on the impact of MPs on soil organisms in various agricultural soils.

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

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

Spatial patterns of microplastics in freshwater bivalves (Bivalvia: Unionidae and Sphaeriidae) relative to municipal wastewater effluent discharges

Microplastics are discharged by municipal wastewater treatment plants (WWTPs); however, their uptake by filter-feeding freshwater bivalves is poorly understood. This study examined the abundance and characteristics of microplastics in wild bivalves from five locations along a 155 km stretch of the Grand River (Ontario, Canada) in 2021-2022, including upstream and downstream of three municipal WWTPs. At each site, fingernail clams (Sphaeriidae spp., n = 5 composites), freshwater mussels (Lasmigona costata, n = 10; gill, digestive gland, and hemolymph), and surface water (n = 3) were sampled at a single timepoint. Microplastics (particles >38 μm to 5 mm) were isolated and visualized via stereomicroscopy, and a subset chemically analyzed using Fourier transform infrared spectroscopy. Fingernail clams contained the highest total blank corrected microparticle counts (35.5 ± 29.4 g-1 [mean ± SD]), mussel tissues ranged from 4.3 ± 4.2 mL-1 in hemolymph to 6.5 ± 8.1 g-1 in digestive gland, and water contained 5.5 ± 2.8 L-1. Fibers were the dominant morphology across all samples, most particles were between 80 μm and 2 mm in length and, of those analyzed chemically, 30.0% were a plastic polymer. At sites downstream of WWTP outfalls, elevated counts were only seen in mussel gills and not in other bivalve tissues or water compared with upstream samples. Although microplastics were found across all sites in both biotic and abiotic compartments, results suggest little impact of WWTP discharges on their uptake in downstream bivalves.

Microplastic distribution and composition in mudflat sediments and varnish clams (Nuttallia obscurata) at two estuaries of British Columbia, Canada: An assessment of potential anthropogenic sources

Widespread microplastic contamination affects the marine-coastal ecosystems in British Columbia, Canada. To understand the characteristics and spatial distribution of of microplastics (MPs), we compared the MPs in sediments (n = 159) and Varnish clams (Nuttallia obscurata; n = 160) collected from two estuarine ecosystems (Cowichan and K'ómoks) experiencing different anthropogenic impacts; primarily resource extraction (i.e., logging) at Cowichan and urban development at K'omoks. Our objective wasto determine the MP abundance levels in sediments and clams and infer possible sources of MPs at the two estuaries. Microplastic polymer type was confirmed through FTIR spectrometry. The average abundance of MPs in sediments were 14.37 ± 11.57 particles/kg in the Cowichan Estuary and 30.96 ± 14.58 particles/kg in the K'ómoks Estuary. Varnish clam samples contained average abundance of 3.62 ± 2.58 particles/g and 2.24 ± 1.96 particles/g in Cowichan and K'ómoks estuaries, respectively. The Cowichan Estuary's marine terminal and K'ómoks Marina were found to be hotspots for MPs, likely due to a combination of industrial and local sources. Fibers were the most common type of MPs found in both sediment (53.34 %) and clam samples (53.5 %) from Cowichan, as well as in clam samples in% K'ómoks, indicating a potential link to textile sources contributing to the widespread presence of MPs in the marine environment. There was no clear signal based on the primary use of the estuary. Polyethylene was the predominant polymer type of MPs found in sediment and clam samples at Cowichan, whereas Polyester was most common at K'ómoks. Our study revealed the ubiquitous nature of these emerging pollutants in the sensitive estuarine environments of BC, with implications for plastic waste management and the reduction of plastic pollution at the regional level.

Environmental impact of microplastics and potential health hazards

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

Vertical distribution characteristics of microplastics and bacterial communities in the sediment columns of Jianhu lake in China

Microorganisms change the properties of microplastics, at the same time, microplastics can also affect the distribution of microorganisms. To investigate this issue, we chose to study Jianhu Lake, a plateau lake in southwestern China, by collecting data at three sampling locations. The microplastics and bacterial communities in the sediment columns of Jianhu Lake were sampled within a 0 to 60 cm profile, and the basic characteristics of microplastic abundance, shape, color, size, and polymer type were determined accordingly, via their collection, separation, extraction, and identification. The bacterial community in the sediment samples were identified using 16S rRNA high-throughput sequencing, and we assessed whether those microplastic characteristics influenced the community composition and structure. We found the abundance of microplastics ranged from 624 to 3050 particles/kg (dw [dry weight]) in the three sediment columns. Line microplastics accounted for the largest proportion and these were found distributed in each layer. The polymer types present in the largest proportions were rayon (RY), polyester terephthalate (PET) and low-density styrene-butadiene-styrene (SBS). Among the bacterial communities in the sediment columns, the dominant phyla were Chloroflexi, Sva0485, Acidobacteriota, etc. The co-occurrence network analysis between the bacterial community and microplastic features in the sediment columns of Jianhu Lake revealed that there was a correlation between them, and the network were more complex at a depth of 20-40 cm. Our results demonstrate that microplastics can affect the diversity and structural characteristics of microbial communities in a lake ecosystem.

Temporal and spatial distribution of microplastics in the freshwater Atibaia river basin, Campinas-SP, Brazil

The contamination of surface waters by microplastics (MPs) is an emerging concern, due to their environmental impact and negative effects on biota. However, in recent years, although the occurrence of these pollutants has been widely reported in marine systems, studies on MPs in freshwater are still scarce in the literature, particularly in Southeastern Brazil. In this context, the current study aimed to provide unprecedented information on the abundance and spatial and temporal distribution of MPs in three sites located in the Atibaia river basin (Southeastern Brazil) - the main river, a tributary, and the discharge of effluent from a sewage treatment plant. Surface water was sampled in four sampling campaigns, two in wet season and two in dry season, between 2019 and 2020, at three sampling points. At each point, 200 L of water were collected with the aid of an aluminium bucket, followed by sieving in the field to isolate the particles between 100 μm and 5000 μm, using stainless steel sieves. Chemical identification of the polymer was performed by ATR-FTIR micro spectroscopy. The abundance of MPs in the water ranged from 188 to 533 items/m3. The water samples with the greatest MPs abundance corresponded to the sampling point that includes the receipt of domestic effluent treated by the local Sewage Treatment Station. The chemical identification of the polymers highlights polyester polyethylene terephthalate (PET), polyethylene (PE), polyvinyl chloride (PVC), and polypropylene (PP) as the most frequent, respectively. This study emphasizes the importance of discharged domestic effluents and rivers as MPs transport systems. Therefore, further studies should be carried out to identify the main sources and contribute to the gathering of information, aiming to mitigate the emission of this pollutant in aquatic systems.

Assessing the external atmospheric input of microplastics: Two strategies based on polymer composition and aging characteristics

Microplastics (MPs) can be transported over long distances in the environment, hence, distinguishing between MPs generated locally and those introduced from external sources is necessary for regional MP pollution management. In this study, MPs pollution in the dust of Siziwang banner (Sizi), a sparsely populated area on the Mongolian Plateau, and Hohhot, a city with large populations, was observed. The high proportion of small MPs in Sizi (<25 μm), combined with the fact that most air masses reaching the area have undergone long-distance transport, supports the presence of external input through atmosphere. Based on the significantly different composition distributions and surface characteristics of the small sized MPs in Sizi and Hohhot, a composition-based Bray-Curtis similarity index (Comp-BCs) and a carbonyl index-based BCs index (CI-BCs) were established. Contributions of the external MPs input to small MPs in Sizi were estimated as 23-36 %, indicating that the role of atmospheric input on MPs pollution in sparsely populated areas should not be overlooked.

Microplastic and antibiotics in waters: Interactions and environmental risks

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

Long-term pollution status of microplastics in sediment of a typical mariculture area

Microplastics (MPs) are pervasive in various environmental media, posing a significant global issue. However, long-term data on marine MPs pollution trends are limited. This study investigates sediment samples from six stations in Sishili Bay, Yellow Sea, collected in 2015, 2018, and 2021, an area impacted by industrial, maricultural, and tourism activities. Findings reveal an annual increase in MPs abundance, with mean concentrations of 92.60 ± 23.93 items/kg.dw in 2015, 146.18 ± 14.80 items/kg.dw in 2018, and 203.21 ± 20.31 items/kg.dw in 2021. MPs distribution is spatially uniform, showing no significant seasonal changes, attributed to the bay's semi-enclosed nature. Predominant MPs are fibers (>70 %) and transparent particles (>35 %), with most particles <1000 μm. PET and Rayon are the main polymers identified. The study emphasizes the escalating MPs pollution in the mariculture area, highlighting the urgent need for targeted pollution control and mitigation strategies.

Fate and mass budget of microplastic in the Beibu Gulf, the northern South China sea

This study investigated the distribution, abundance, and mass budget of microplastics (MPs) in the Beibu Gulf, Northern South China Sea, focusing on their ecological significance and anthropogenic influence. Microplastics were found in all water and sediment samples, with concentrations in surface water ranging from 0.10 to 0.89 items/m³, and in bottom water from 0 to 0.85 items/m³. Sediment samples exhibited higher levels, ranging from 13.12 to 155.59 items/kg. The spatial distribution revealed higher concentrations along the northern Gulf and Guangxi Province, suggesting significant human influence from coastal activities, such as mariculture and industrial discharges. The study utilized both field data and a mass balance box model to estimate the MPs mass budget, revealing that oceanic flow and riverine discharge are major contributors, accounting for 49% and 52% of MPs, while Atmospheric deposition and sedimentation represents 8% and 1%, respectively. The inventory estimation calculated that 0.24 tons of MPs exist in the water column, and 137 tons in the sediment, emphasizing the substantial environmental burden posed by these pollutants. The significance of this research lies in its comprehensive assessment of MPs in a semi-enclosed gulf, providing critical insight into the role of coastal and hydrodynamic processes in MP distribution. This study highlights the urgent need for better waste management practices in coastal regions to mitigate microplastic pollution and its detrimental effects on marine ecosystems.

Abundance and distribution of microplastics in benthic sediments and Cladocera taxa in a subtropical Austral reservoir

Pollution of the natural environment by microplastics has become a global issue in ecosystems as it poses a potential long-term threat to biota. Microplastics can accrue in high abundances in sediments of aquatic ecosystems while also contaminating pelagic filter feeders, which could transfer pollutants up trophic webs. We assess the abundance and distribution of microplastics in benthic sediments and Cladocera taxa in a subtropical Austral reservoir using a combination of geospatial techniques, physicochemical analyses, diversity indices, and multivariate statistics between two seasons (i.e., hot-wet and cool-dry). We found particularly high densities of microplastics during the cool-dry season for both sediments (mean 224.1 vs. 189 particles kg-1 dry weight) and Cladocera taxa (0.3 particles per individual). Cladocera microplastic shapes were dominated by fibers with high densities of the transparent color scheme. Pearson correlation results indicated that sediment microplastic abundances were negatively correlated with chlorophyll-a concentration, temperature, and resistivity, whereas they were positively correlated with pH and salinity during the hot-wet season, with no variables significant in the cool-dry season. Cladocera microplastic abundances were positively correlated with conductivity and salinity during the cool-dry season, but no variables in the hot-wet season. These findings provide insights into the role of reservoirs as microplastic retention sites and the potential for uptake and transfer from lower trophic groups. These insights can be used to strengthen future monitoring and intervention strategies. Integr Environ Assess Manag 2024;20:2256-2270. © 2024 SETAC.

Modeling the settling and resuspension of microplastics in rivers: Effect of particle properties and flow conditions

Microplastics have numerous different shapes, affecting the fate and transport of these particles in the environment. However, theoretical models generally assume microplastics to be spherical. This study aims to develop a modeling approach that incorporates the shapes of microplastics to investigate the vertical transport of microplastics in rivers and simulate the effect of particle and flow characteristics on settling and resuspension. To achieve these aims, a mechanistic model was developed utilizing the mass-balance and hydrodynamic equations. Scenario analysis was implemented assigning different values to model parameters, such as bed shear stress, shape factor and particle size to simulate the effect of flow patterns and particle properties. The model outcomes revealed that the residence time of microplastics in the water column was longest in medium bed shear stress, whilst it was shortest in low bed shear stress. This suggests that the influence of turbulence is not unidirectional; it can both increase and decrease microplastic concentrations and residence time in the water column. According to the scenario analysis, the settling flux of microplastics was the highest for near-spherical particles and increased with the size of the particles, as well as with increasing bed shear stress. However, the resuspension of particles was primarily influenced by increasing bed shear stress, but the ranking of resuspension flux values for different shaped and sized microplastics exhibited alterations with changing flow patterns. Turbulent conditions predominantly influenced the resuspension of near-spheres and large microplastics. On the contrary, the settling of fibers and small microplastics were significantly influenced by changing flow patterns, whereas near-spheres and largest particles were least affected. The model results were sensitive to changes in shape factor developed for this model, therefore this parameter should be improved in future studies.

Assessing the ecotoxicological effects of novel cellulose nanocrystalline glitter compared to conventional polyethylene terephthalate glitter: Toxicity to springtails (Folsomia candida)

Glitter is a type of microplastic, and thus there is a need to assess its potential impacts on the environment and to assess the potential for non-plastic cellulose nanocrystal structurally colored glitters as safe and sustainable replacements. The ecotoxicity of glitter has been mostly ignored in the research literature, with only a few published studies focusing on aquatic organisms. Therefore, an exposure experiment was conducted to examine the impact of conventional polyethylene terephthalate (PET) glitter as well as untreated and heat-treated cellulose nanocrystal (CNC) based glitter on the survival, reproduction, and length of Folsomia candida (springtail). Folsomia candida reproduction was reduced by 61% (P = 0.013) after exposure to PET glitter at 1000 mg/kg, while no significant effects were observed on F. candida survival and length. In contrast, there were no significant impacts on F. candida survival, length, or reproduction when exposed to untreated or heat-treated CNC glitter. These results indicate that exposure to PET glitter may impact soil invertebrates at the population level, and that CNC glitter has potential as a biodegradable non-plastic alternative to PET glitter to decrease detrimental effects on soil ecosystems.

Occurrence, characteristics, and risk assessment of microplastics and polycyclic aromatic hydrocarbons associated with microplastics in surface water and sediments of the Konya Closed Basin, Turkey

The presence of polycyclic hydrocarbons (PAHs) and microplastics (MPs) in aquatic environments affects the ecosystems and threatens human health. In this study, the abundance, composition, and morphological characteristics of MPs were determined for the first time in the inland freshwater resources of the Konya Closed Basin, Turkey. The abundance of MPs ranged from 1139 to 23,444 particles/m3 and 150 to 3510 particles/kg in the surface water and sediment, respectively. Fragments and fibers were the most abundant MP shapes in the surface waters (51%, 34%) and sediments (29%, 40%), followed by films, pellets, and foams. Transparent and white MPs were present at the highest percentage in surface waters (72%) and sediments (69%), followed by blue, grey, black, brown, and green. In addition, polyethylene, polypropylene, and cellophane were identified as the main polymers in surface waters (34%, 25%, 24%) and sediments (37%, 17%, 31%). In the Konya Closed Basin, 35% of the surface water samples and 54% of the sediment samples were exposed to very high contamination (CF ≥ 6). Surface waters (PLI: 2.51) and sediments (PLI: 1.67) in the basin were contaminated (PLI > 1) with MPs. The 16 PAHs sorbed on MPs in the surface water and sediment ranged from 394 to 24,754 ng/g and from 37 to 18,323 ng/g, respectively. Phenanthrene and fluoranthene were the most abundant PAHs sorbed on MPs in all surface waters and sediments. Two to three-ring PAH compounds sorbed on MPs were also dominantly detected in surface waters and sediments, accounting for 68% and 78% of the total 16 PAHs, respectively. The source of PAHs carried by MPs in the Konya Closed Basin was mainly of petrogenic origin. Incremental lifetime cancer risk (ILCR) results indicated that the maximum ILCR values were higher than the EPA acceptable level (10-6) for child (2.95 × 10-5) and adult (1.46 × 10-4), indicating a potential cancer risk.

Microplastic accumulation in water from protected areas in Western Forest Complex of Thailand

Microplastics (MPs) are emerging as ubiquitous environmental pollutants worldwide. However, no research has been conducted in freshwater ecosystems within Thai protected areas (PAs), where biodiversity and natural resources are safeguarded for human well-being. The aim of this study was to explore the occurrence and abundance of potential MPs in the water of freshwater ecosystems in Thai PAs and to examine factors affecting their presence in the Western Forest Complex in Thailand (WEFCOM). Seventy water samples were collected from eight PAs in WEFCOM using a 20 μm plankton net. The water samples underwent digestion, density separation, and filtration. Potential MPs were visually identified under a stereomicroscope, and their chemical composition was further characterized using FTIR. The results revealed a 98.57 % potential MP prevalence in the water samples, with an average abundance of 0.30 ± 0.32 item·L-1. The quantities of potential MPs among PAs were significantly different (H = 17.88, p = 0.01). Fibers (68.93 %) were the most frequently identified potential MPs, with the dominant colors being blue (22.40 %) and black (20.03 %), mostly small-sized MPs (0.05-0.5 mm; 41.80 %). The major chemical plastic types included low-density polyethylene, polyethylene, polyethylene terephthalate, polypropylene, polyethylene/polypropylene copolymer, polyester, and natural fibers. The abundance of potential MPs varied significantly among PAs, shapes, colors, and sizes (p < 0.01). Furthermore, potential MP abundance correlated with the number of tourists (p < 0.05). Proximity to open waste dumping (p < 0.01) and lower elevation (p < 0.05) tended to accumulate more potential MPs. This research suggests potential sources of microplastics in Thai PAs from wastewater effluent, human activities, and recreational activities, highlighting the urgent need for research to develop appropriate waste management technologies in Thai PAs and to raise awareness among local people and tourists about microplastic pollution.

Microplastics monitoring in freshwater systems: A review of global efforts, knowledge gaps, and research priorities

The escalating production of synthetic plastics and inadequate waste management have led to pervasive microplastic (MP) contamination in aquatic ecosystems. MPs, typically defined as particles smaller than 5 mm, have become an emerging pollutant in freshwater environments. While significant concern about MPs has risen since 2014, research has predominantly concentrated on marine settings, there is an urgent need for a more in-depth critical review to systematically summarize the current global efforts, knowledge gaps, and research priorities for MP monitoring in freshwater systems. This review evaluates the current understanding of MP monitoring in freshwater environments by examining the distribution, characteristics, and sources of MPs, alongside the progression of analytical methods with quantitative evidence. Our findings suggest that MPs are widely distributed in global freshwater systems, with higher abundances found in areas with intense human economic activities, such as the United States, Europe, and China. MP abundance distributions vary across different water bodies (e.g., rivers, lakes, estuaries, and wetlands), with sampling methods and size range selections significantly influencing reported MP abundances. Despite great global efforts, there is still a lack of harmonized analyzing framework and understanding of MP pollution in specific regions and facilities. Future research should prioritize the development of standardized analysis protocols and open-source MP datasets to facilitate data comparison. Additionally, exploring the potential of state-of-the-art artificial intelligence for rapid, accurate, and large-scale modeling and characterization of MPs is crucial to inform effective strategies for managing MP pollution in freshwater ecosystems.

Microplastics and Anthropogenic Particles in Recreationally Caught Freshwater Fish from an Urbanized Region of the North American Great Lakes

BACKGROUND

Microplastics are a pervasive contaminant cycling through food webs-leading to concerns regarding exposure and risk to humans.

OBJECTIVES

We aimed to quantify and characterize anthropogenic particle contamination (including microplastics) in fish caught for human consumption from the Humber Bay region of Lake Ontario. We related quantities of anthropogenic particles to other factors (e.g., fish size) that may help in understanding accumulation of microplastics in fish.

METHODS

A total of 45 samples of six fish species collected from Humber Bay in Lake Ontario near Toronto, Ontario, Canada, were examined for anthropogenic particles in their gastrointestinal (GI) tracts and fillets. Using microscopy and spectroscopy, suspected anthropogenic particles were identified and characterized.

RESULTS

We observed anthropogenic particles in the GI tracts and fillets of all species. Individual fish had a mean ± standard deviation of 138 ± 231 anthropogenic particles, with a single fish containing up to 1,508 particles. GI tracts had 93 ± 226 particles/fish (9.8 ± 32.6 particles/gram), and fillets had 56 ± 61 particles/fish (0.5 ± 0.8 particles/gram). Based on a consumption rate of 2 servings/week, the average yearly human exposure through the consumption of these fish fillets would be 12,800 ± 18,300 particles.

DISCUSSION

Our findings suggest that consumption of recreationally caught freshwater fish can be a pathway for human exposure to microplastics. The elevated number of particles observed in fish from Humber Bay highlights the need for large-scale geographic monitoring, especially near sources of microplastics. Currently, it is unclear what the effects of ingesting microplastics are for humans, but given that recreationally caught freshwater fish are one pathway for human exposure, these data can be incorporated into future human health risk assessment frameworks for microplastics. https://doi.org/10.1289/EHP13540.

Seasonal variation, spatial distribution and risk assessment of microplastics in surface waters of Periyar River, Kerala, India

Microplastics, an emerging contaminant, are widespread in oceans around the world, and rivers are the key conveyors of these pollutants into the oceans. There exists a dearth of available data pertaining to seasonal fluctuation, spatial distribution and risk assessment of microplastics in rivers extending from upper reaches to the lower reaches. The collection of such data is of utmost importance for the purpose of formulating beneficial management strategies for riverine microplastics. In order to bridge this research gap, an investigation was made in the Periyar River in Kerala, India, which is exposed to anthropogenic stress and is at risk of microplastic pollution. A total of eighteen sites (six sites each from downstream, midstream and upstream) along the 244 km of the river were investigated across three seasons in a year. The study revealed a discernible pattern in the spatial distribution of microplastic concentrations, wherein there was a rise in abundance from the upstream to midstream and then a sudden increase of abundance along the downstream regions towards the lower reaches. The highest mean microplastic abundance of 124.95 items/L was obtained during the monsoon season followed by post-monsoon season i.e. 123.21 items/L and pre-monsoon i.e. 120.50 items/L. The predominant forms of microplastics were found to be fibres, fragments and filaments. Most prevalent polymer types acquired were polyethylene (PE) and polypropylene (PP). Pollution hazard index (PHI) and pollution load index (PLI) were also evaluated to assess the water quality of this river. The findings of this study conclude that the Periyar River is polluted with microplastics throughout its course and offer significant insights into the detection of microplastic origins in river systems and lend support to the implementation of potential measures aimed at mitigating their impact.

Modeling of microplastics degradation in aquatic environments using an experimental plan

The aim of this article is to apply advanced predictive modeling techniques to understand the degradation process of microplastics in aquatic environments. Utilizing a Fractional Factorial Central Composite Experimental Plan, this study seeks to develop precise predictive statistical models that enable forecasting the quantity of pollutants generated during the degradation of microplastics under various environmental conditions. This tool was applied to model changes in DOC (dissolved organic carbon) and DEHP (bis(2-ethylhexyl) phthalate) values during the degradation of microplastics in aquatic ecosystems. The methods were developed using data derived from laboratory tests conducted using the GC-MS technique. The obtained approximating functions, considering factors such as degradation time, water temperature, and particle size, significantly reduced the analysis time. A two-stage verification of the approximating functions was conducted, considering the accuracy of the function form, its adequacy, the statistical significance of input variables, and their correlation with DOC and DEHP. The employed a Fractional Factorial Central Composite Experimental Plan allowed for the simultaneous reduction in the number of experiments and prediction of the influence of variables on the output values. Precise predictive models support understanding of the microplastic degradation process, facilitating the development of effective strategies for managing this pollution.

The presence and physico-chemical properties of microplastics in seawater, sediment, and several organs of the spotted scat fish (Scatophagus argus, Linnaeus, 1766) collected from different locations along the East Java coast in Indonesia

A comprehensive study was undertaken to examine the contamination of spotted scat fish (Scatophagus argus) with microplastics (MP) in various locations along the East Java coast of Indonesia. The purpose of this study was to collect detailed information regarding the abundance, color, shape, size, type of polymer, and chemical components of the MP. The findings of this study indicated that MP exhibiting distinct attributes-including a specific fiber type, black coloration, and a size range of 1000- <5000 μm-was most abundant in the gill, stomach, and intestines of spotted scat fish of varying lengths. And MP with a size range of 100-<500 μm was prevalent in the sediment. MP with black fragments measuring less than 100 μm in diameter were found primarily in seawater. A positive correlation was identified between fish length and MP abundance in the intestines, as indicated by the Spearman correlation coefficient. Conversely, a negative correlation was detected between fish length and MP abundance in the gills. The findings of the Fourier transform infrared spectroscopy and Gas chromatography-mass spectrometry analyses, which indicate the presence of various polymers and chemical substances including plasticizers (e.g., diethyl phthalate, decane, and eicosane), stabilizers (2-piperidinone, hexadecanoic acid, mesitylene, and 2,4-Di-tert-butylphenol), and flame retardant (cyclododecene), in fish, are of the utmost importance. These substances have the potential to endanger the health of both animals and humans if they are ingested through the food chain.

Short- and medium-chain chlorinated paraffins in surface sediment from Lake Ontario

Concentrations of short- and medium-chain chlorinated paraffins (SCCPs and MCCPs) were analyzed and investigated in surficial sediment collected in 2018 from ten different nearshore sites in Lake Ontario and the St. Lawrence River influenced by inputs from varying urban and historical land uses. Sites were grouped into two categories of tributary and lake according to their location. Results show that tributary sites had higher concentrations of total chlorinated paraffin (CP) than lake sites. Humber Bay, a lake site, had the highest total CP concentration (55,000 ng/gTOC) followed by Humber River, a tributary site (50,000 ng/gTOC). The lowest concentrations were found in eastern Lake Ontario and Lake St. Francis in the St. Lawrence River (540 ng/gTOC). Higher concentrations of chlorinated paraffins (CPs) were found where runoff and wastewater inputs from urban areas, current industrial activities, and population were the greatest. Levels of MCCPs were higher than SCCPs at all sites but one, Lake St. Francis. Among the SCCPs, C13 and among the MCCPs C14 were the dominant chain length alkanes, with C14 being the highest among both groups. The SCCPs and MCCPs profiles suggest that they can be used to distinguish between sites impacted by local sources vs. sites impacted by short-/long-range transport of these chemicals.

Microplastics in Asian rivers: Geographical distribution, most detected types, and inconsistency in methodologies

Microplastics pose a significant environmental threat, with potential implications for toxic chemical release, aquatic life endangerment, and human food chain contamination. In Asia, rapid economic growth coupled with inadequate waste management has escalated plastic pollution in rivers, positioning them as focal points for environmental concern. Despite Asia's rivers being considered the most polluted with plastics globally, scholarly attention to microplastics in the region's freshwater environments is a recent development. This study undertakes a systematic review of 228 scholarly articles to map microplastic hotspots in Asian freshwater systems and synthesize current research trends within the continent. Findings reveal a concentration of research in China and Japan, primarily investigating riverine and surface waters through net-based sampling methods. Polyethylene (PE), polypropylene (PP), and polyethylene terephthalate (PET) emerge as the predominant microplastic types, frequently observed as fibers or fragments. However, the diversity of sampling methodologies and reporting metrics complicates data synthesis, underscoring the need for standardized analytical frameworks to facilitate comparative analysis. This paper delineates the distribution of microplastic hotspots and outlines the prevailing challenges and prospects in microplastic research within Asian freshwater contexts.

Anthropogenic particle abundance and characteristics in seawater and intertidal sediments of the Tonkin Bay Coast (North Vietnam)

Microplastics (MPs, plastic items from 1 µm to 5 mm in size) are present in all environmental compartments. The evaluation of their concentration, fate, and spatial distribution is still a challenge for the scientific community. This concern is just debuting in developing countries, (i.e., Asia, South America, and Africa). This study deals with the MP contamination in the abiotic marine compartments of Northern Vietnam: seawater and intertidal sediments. Four sites located in the intertidal zone or near the coastline in Tonkin Bay, Vietnam were studied. A total of 16 samples (eight for each compartment) were collected in July 2020 (rainy season) and January 2021 (dry season). Anthropogenic particles (total observed fibers and fragments) were found at levels ranging from 3 to 303 particles/m3 in seawater and from 63 to 955 particles/kg dry weight in sediments. Most of these were fibers less than 300-µm long. Higher levels of seawater at the Nam Dinh site were found in the rainy season compared to the dry one. As the river flow was estimated six times higher during the rainy season than during the dry season, these results suggest the river discharge is a potential source of contamination for the coastal zone. The temporal variability was lower for the sediments than for the seawater, suggesting the long-term integration of the anthropogenic particles in this compartment. A small portion of sorted particles were analyzed by µFTIR (8.35%), and this sub-sample was only composed of fragments. Still, fragments were mostly composed of polypropylene (PP, 82%), polyethylene (PE, 9%), and polystyrene (PS, 9%). The fragment size was similar in the two studied compartments, but it was dependent on polymer types since PS fragments (140 ± 17 µm) were smaller than those made of PE (622 ± 123 µm) and PP (869 ± 905 µm). Future works should investigate the smallest fraction of MP (even nanoplastics) as well as find solutions in order to mitigate MP contamination in the marine environment.

The distribution of sediment microplastics assemblages is driven by location and hydrodynamics, not sediment characteristics, in the Gulf of Maine, USA

Microplastics (MP) are found in marine sediments across the globe, but we are just beginning to understand their spatial distribution and assemblages. In this study, we quantified MP in Gulf of Maine, USA sediments. MP were extracted from 20 sediment samples, followed by polymer identification using Raman spectroscopy. We detected 27 polymer types and 1929 MP kg-1 wet sediment, on average. Statistical analyses showed that habitat, hydrodynamics, and station proximity were more important drivers of MP assemblages than land use or sediment characteristics. Stations closer to one another were more similar in their MP assemblages, tidal rivers had higher numbers of unique plastic polymers than open water or embayment stations, and stations closer to shore had higher numbers of MP. There was little evidence of relationships between MP assemblages and land use, sediment texture, total organic carbon, or contaminants.

Contribution of different land use catchments on the microplastic pollution in detention basin sediments

The assessment of microplastic (MP) pollution in urban areas is essential considering its abundance in freshwater, particularly due to urban wet weather discharge. The precise sources of MPs must be identified to better understand its characteristics. This study examines the relationship between MP pollution in detention basin sediments and land use in the investigated catchments. The study of stormwater management infrastructure, mainly in detention basins, has enabled the quantification of MP abundance in sediments conveyed by stormwater in urban areas. Sediment sampling was conducted in ten detention basins and one combined sewer overflow (CSO) structure in the Lyon metropolitan area, France. These basins correspond to stormwater outlets of representative urban catchment areas. MP extraction involves densimetric separation and organic matter degradation. MPs were then characterized using micro-Fourier infrared spectroscopy and siMPle software. This protocol identified MPs between 50 and 500 μm in the study sites. This study highlights the high abundance in the collected sediment samples, ranging from 2,525 to 1,218,82 MP kg-1 by dry weight sediment. The MPs found have a median size around 115 μm, making them very small MPs that are mainly composed of polypropylene followed by polyethylene and polystyrene or polyethylene terephthalate. The abundance of MPs in sediments is associated with the land use type. Catchments in predominantly industrial and commercial zones were more significantly polluted with MPs compared with those in predominantly agricultural or heterogeneous zones. Finally, statistical analyses revealed links between sedimentary and urban parameters and MPs concentrations. Several recommendations are given for future research, notably concerning the analyzing of stormwater sediments to understand the sources of MP pollution.

Microplastic in Dredged Sediments: From Databases to Strategic Responses

Microplastics (MPs) accumulate in sediments, yet guidelines for evaluating MP risks in dredged sediments are lacking. The objective of this study was to review existing literature on MPs in sediments to improve fundamental knowledge of MP exposures and develop a publicly available database of MPs in sediments. Twelve percent of the reviewed papers (nine studies) included sediment core samples with MP concentrations generally decreasing with depth, peaking in the top 15 cm. The remaining papers evaluated surficial grab samples (0 to 15 cm depth) from various water bodies with MPs detected in almost every sample. Median MP concentrations (items/kg dry sediment) increased in this order: lakes and reservoirs (184), estuarine (263), Great Lakes nearshore areas and tributaries (290), riverine (410), nearshore marine areas (487), dredge activities (817), and harbors (948). Dredging of recurrent shoaling sediments could be expected to contain MPs at various depths with concentrations influenced by the time elapsed since the last dredging event. These results offer key insights into the presence and variability of MPs in dredged sediments, informing environmental monitoring and risk assessment strategies.

Microplastic pollution calls for urgent investigations in stygobiont habitats: A case study from Classical karst

Microplastic pollution in karst systems is still poorly studied, despite the presence of protected species and habitats, and important water reserves. Vulnerable key species hosted in these habitats could consume or assimilate microplastics, which can irreversibly damage management efforts, and thus ecosystems functionality. This can be particularly true for subterranean water habitats where microplastic pollution effects on wildlife management programs are not considered. The aim of this study is to provide a case study from the Classical Karst Region, which hosts peculiar habitats and key species protected at European level, such as the olm Proteus anguinus. As this area has been deeply exploited and modified over time, and is adjacent to highways, roads and railways, which could contribute to pollution within the karst system, threatening the ecosystems, it provides a perfect model system. In this study we collected and investigated water and sediment samples from aquatic environments of surface and subterranean habitats hosting several subterranean environment-adapted organisms. Examined particles were counted and characterized by size, color and shape via visual identification under a microscope, with and without UV light. Furthermore, spectroscopic analyses were carried out in order to identify microplastics typology. Microplastics were found in all examined habitats. In water, microplastics concentration ranged from 37 to 86 items/L, in sediments from 776 to 2064 items/kg. Fibre-shape was the main present, followed by fragments and beads, suggesting multiple sources of pollution, especially textile products. Most of the particles were fluorescent under UV light and were mainly transparent, while not-fluorescent ones were especially black, blue or brown. Samples contained especially polyesters and copolymers. These results highlight intense MP pollution in karst areas, with significant impacts on water quality, and potential effects on subterranean environment-dwelling species. We stress the importance of monitoring pollution in these critical environments for biodiversity and habitat conservation: monitoring in karst areas must become a priority for habitat and species protection, and water resources management, improving analyses on a larger number of aquatic surface and subterranean habitats.

Microplastic contamination in wastewater: Sources, distribution, detection and remediation through physical and chemical-biological methods

Microplastics are tiny plastic particles smaller than 5 mm. that have been widely detected in the environment, including in wastewater. They originate from various sources including breakdown of larger plastic debris, release of plastic fibres from textiles, and microbeads commonly used in personal care products. In wastewater, microplastics can pass through the treatment process and enter the environment, causing harm to biodiversity by potentially entering the food chain. Additionally, microplastics can act as a vector for harmful pollutants, increasing their transport and distribution in the environment. To address this issue, there is a growing need for effective wastewater treatment methods that can effectively remove microplastics. Currently, several physical and chemical methods are available, including filtration, sedimentation, and chemical degradation. However, these methods are costly, low efficiency and generate secondary pollutants. Furthermore, lack of standardization in the measurement and reporting of microplastics in wastewater, makes it difficult to accurately assess microplastic impact on the environment. In order to effectively manage these issues, further research and development of effective and efficient methods for removing microplastics from wastewater, as well as standardization in measurement and reporting, are necessary to effectively manage these detrimental contaminants.

Microparticles in Wild and Caged Biota, Sediments, and Water Relative to Large Municipal Wastewater Treatment Plant Discharges

Anthropogenically modified microparticles including microplastics are present in municipal wastewater treatment plant (WWTP) effluents; however, it is unclear whether biotic exposures are elevated downstream of these outfalls. In the fall of 2019, the present study examined whether microparticle levels in resident fish, environmental samples, and caged organisms were elevated near the Waterloo and Kitchener WWTP outfalls along the Grand River, Ontario, Canada. Wild rainbow darters (Etheostoma caeruleum) were collected from a total of 10 sites upstream and downstream of both WWTPs, along with surface water and sediment samples to assess spatial patterns over an approximately 70-km river stretch. Amphipods (Hyalella azteca), fluted-shell mussels (Lasmigona costata), and rainbow trout (Oncorhynchus mykiss) were also caged upstream and downstream of one WWTP for 14 or 28 days. Whole amphipods, fish digestive tracts, and mussel tissues (hemolymph, digestive glands, gills) were digested with potassium hydroxide, whereas environmental samples were processed using filtration and density separation. Visual identification, measurement, and chemical confirmation (subset only) of microparticles were completed. Elevated abiotic microparticles were found at several upstream reference sites as well as at one or both wastewater-impacted sites. Microparticles in amphipods, all mussel tissues, and wild fish did not show patterns indicative of increased exposures downstream of effluent discharges. In contrast, elevated microparticle counts were found in trout caged directly downstream of the outfall. Across all samples, cellulose fibers (mainly blue and clear colors) were the most common. Overall, results suggest little influence of WWTP effluents on microparticles in biota but rather a ubiquitous presence across most sites that indicates the importance of other point and nonpoint sources to this system. Environ Toxicol Chem 2024;00:1-15. © 2024 His Majesty the King in Right of Canada and The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC. Reproduced with the permission of the Minister of Environment and Climate Change Canada.

Abundance and distribution of microplastics on sandy beaches of the eastern Moroccan Mediterranean coast

Microplastics (MPs) were investigated at 19 sandy beaches along the eastern Mediterranean Moroccan coast. Sediment samples (5 mm-63 μm) were analyzed to identify MPs abundance, size, shape, color and nature. MPs concentration ranged from 40 ± 7.4 to 230 ± 48.6 MPs kg-1; fibrous MPs were the most abundant (74.72 %), followed by fragments (20.26 %), films (3.27 %), pellets (1.42 %) and foams (0.33 %). Large MPs (1-5 mm) accounted for 58 %, while small (< 1 mm) for 42 %. The 1-2 mm fraction of sediments presented the greatest amounts (30.67 %) of MPs. Transparent (50 %) and blue (17 %) were most common colors and most of particles were angular and irregularly shaped. Fourier Transform Infrared Spectroscopy (FTIR) analysis showed that PE (Polyethylene), PS (Polystyrene) and PP (Polypropylene) and PVC (Polyvinyl chloride) were the most common polymers. These findings revealed a moderate level of microplastic pollution along the beaches of the eastern Moroccan Mediterranean coast.

Microplastics as carriers of toxic pollutants: Source, transport, and toxicological effects

Microplastic pollution has emerged as a new environmental concern due to our reliance on plastic. Recent years have seen an upward trend in scholarly interest in the topic of microplastics carrying contaminants; however, the available review studies have largely focused on specific aspects of this issue, such as sorption, transport, and toxicological effects. Consequently, this review synthesizes the state-of-the-art knowledge on these topics by presenting key findings to guide better policy action toward microplastic management. Microplastics have been reported to absorb pollutants such as persistent organic pollutants, heavy metals, and antibiotics, leading to their bioaccumulation in marine and terrestrial ecosystems. Hydrophobic interactions are found to be the predominant sorption mechanism, especially for organic pollutants, although electrostatic forces, van der Waals forces, hydrogen bonding, and pi-pi interactions are also noteworthy. This review reveals that physicochemical properties of microplastics, such as size, structure, and functional groups, and environmental compartment properties, such as pH, temperature, and salinity, influence the sorption of pollutants by microplastic. It has been found that microplastics influence the growth and metabolism of organisms. Inadequate methods for collection and analysis of environmental samples, lack of replication of real-world settings in laboratories, and a lack of understanding of the sorption mechanism and toxicity of microplastics impede current microplastic research. Therefore, future research should focus on filling in these knowledge gaps.

Photodegradation of biodegradable plastics in aquatic environments: Current understanding and challenges

Direct and indirect photolysis are important abiotic processes in aquatic environments through which plastics can be transformed physically and chemically. Transport of biodegradable plastics in water is influenced by vertical mixing and turbulent flow, which make biodegradable plastics remain susceptible to sunlight and photolysis despite their high density. In general, biodegradable plastics are composed of ester containing polymers (e.g., poly(butylene succinate), polyhydroxyalkanoate, and polylactic acid), whereas non-biodegradable plastics are composed of long chains of saturated aliphatic hydrocarbons in their backbones (e.g., polyethylene, polypropylene, and polystyrene). Based on the reviewed knowledge and discussion, we may hypothesize that 1) direct photolysis is more pronounced for non-biodegradation than for biodegradable plastics, 2) smaller plastics such as micro/nano-plastics are more prone to photodegradation and photo-transformation by direct and indirect photolysis, 3) the production rate of reactive oxygen species (ROS) on the surface of biodegradable plastics is higher than that of non-biodegradable plastics, 4) the photodegradation of biodegradable plastics may be promoted by ROS produced from biodegradable plastics themselves, and 5) the subsequent reactions of ROS are more active on biodegradable plastics than non-biodegradable plastics. Moreover, micro/nanoplastics derived from biodegradable plastics serve as more effective carriers of organic pollutants than those from non-biodegradable plastics and thus biodegradable plastics may not necessarily be more ecofriendly than non-biodegradable plastics. However, biodegradable plastics have been largely unexplored from the viewpoint of direct or indirect photolysis. Roles of reactive oxygen species originating from biodegradable plastics should be further explored for comprehensively understanding the photodegradation of biodegradable plastics.

Interactions between microplastics and Culex sp. larvae in wastewater

Microplastics (MPs) are a growing issue because they endanger both aquatic organisms and humans. Studies have indicated that wastewater treatment plants (WWTPs) are one of the major contributors to MPs in the environment. However, studies on the abundance of MP contamination in WWTPs and its transmission into aquatic organisms are still scarce, especially in Egypt. The goal of this study was to examine the temporal fluctuations in the distribution of MPs in surface water and the dominant macroinvertebrate fauna (Culex sp. larvae) in a fixed wastewater basin in Sohag Governorate, Egypt. The average of MPs in the surface water was 3.01 ± 0.9 particles/L. The results indicated to seasonal variation of MP abundance in the wastewater basin that was significantly higher in winter than in the other seasons. The risk index for polymers (H), pollution load index (PLI), and potential ecological risk index (RI) were used to assess the degree of MP contamination. The basin has moderate H values (<1000) because of the presence of polymers with moderate hazard scores such as polyester (PES), polyethylene (PE), and polypropylene (PP). According to the PLI values, surface water is extremely contaminated with MPs (PLI: 88 to 120). The RI values of surface water showed higher ecological risk (level V). MPs in Culex sp. larvae were seasonally changed with an 85% detection rate, and an abundance average of 0.24 ± 0.65 particles/ind, MP concentration in Culex sp. larvae was influenced by the MP characters (shape, color, and polymer). The larvae of Culex sp. showed a greater preference for black and red fibrous polyester (PES) with sizes (<1000 μm) of MPs. These findings suggest that Culex sp. larvae prefer ingesting MPs that resemble their food. It is possible to overestimate Culex sp.'s preference for lower sizes because of their catabolism of MPs. To better understand the preferences of Culex sp. larvae for MPs, further controlled trials should be conducted. PRACTITIONER POINTS: Wastewater is highly contaminated with microplastics (MPs) in the different seasons. First report of detection of the seasonal abundance of MP in Culex sp. larvae. Culex sp. larvae showed a stronger feeding preference for MPs with specific characteristics. Smaller size and blue polyester fibers were the dominant characteristics of MPs in wastewater.

Assessment of microplastic abundance and impact on recreational beaches along the western Algerian coastline

Microplastics (MPs) have attracted global attention due to their ubiquity and potential impact on the environment. However, MPs are poorly documented along the Algerian coast. To address this data gap, this study investigated the presence of MPs on three recreational beaches in western Algeria (Stidia, Sablettes and Mersat El Hadjaj). The mean MP abundance for the three beaches was estimated at 55.47 ± 48.01 items/m2. Characterization of MPs shape revealed that fragments (79.81 %) were dominant, followed by pellets (10.58 %), filaments (5.57 %), and foam (3.85 %). An assessment of the Microplastic Pollution Index, the Pellet Pollution Index, and the Coefficient of Microplastic Impact, revealed the presence of very low to moderate levels of MPs on the beaches. This presence was associated with minimal beach pollution and moderate overall impact. The sector analysis approach results confirm that there are two different magnitudes of MPs presence that can negatively impact on the environmental quality of the studied beaches.

Seasonal variations of microplastics in surface water and sediment in an inland river drinking water source in southern China

The aim of this study was to examine microplastic (size distribution of 0.05-5 mm) occurrence and distribution in drinking water source of XJ River during both flooding and dry periods. Surface water and sediment samples were collected from the CS City section of the river in August and December 2020. During the flooding period, microplastic abundances were observed at 0.72-18.6 (7.32 ± 2.36) items L-1 in surface water and 26.3-302 (150 ± 75.6) items kg-1 dry weight (dw) in sediment. In the dry period, abundances were slightly higher at 2.88-17.7 (11.0 ± 3.08) items L-1 and 27.0-651 (249 ± 182) items kg-1 dw, respectively. Microplastics were found in higher concentrations in urban areas and downstream of wastewater treatment plants, suggesting anthropogenic sources. The diversity in shapes, colors, and types of microplastics in surface waters and sediments indicates specialized enrichment processes and persistent sources of microplastic pollution. Approximately 60 % of the microplastic particles identified fall within the 50-100 μm range. Furthermore, a significant correlation was observed between these smaller-sized particles and the overall prevalence of microplastics. Fourier-transform infrared spectroscopy and scanning electron microscopy indicated that the microplastics had been subjected to weathering in the environment, contributing to the production of oxygen-containing functional groups and surface cleavage features. The utilization of energy dispersive spectroscopy revealed the presence of microplastics associated with various heavy metals, highlighting the intricate nature of microplastic pollution. Moreover, the high abundance of microplastics may pose a potential ecological risk to the aquatic environment of the XJ River. The results of this study demonstrate concerning levels of microplastics in the XJ River, despite its status as a high-quality water source.

Investigation of microplastics and microplastic communities in selected river and lake basin soils of Thiruvananthapuram District, Kerala, India

Riparian areas are highly dynamic bio-geophysical settings with a surge of waste deposition predominantly including land-based plastic discards. These polymer discards are destined to be the prime constitution of marine "plastisphere." The polymer fate is determined by waterbodies, where the chances of plastic retention are higher, eventually mediating the formation of microplastics (MPs) in years or decades. Such formed MPs are a potential threat to the aqua bio-regime. A systematic investigation of three waterbody basin soils (Karamana River, Killiyar, and Akkulam-Veli Lake) showed the presence of MPs in all the samples analyzed with varying sizes, shapes, colors, and compositions. MPs of the shapes flakes, fragments, filaments, sheets, foams, and fibers were observed with dimensions 0.3-4.7 mm. Most of the particles were white in hue (WT), followed by colorless (CL), light yellow (L.Y), light brown (L.B), orange (OR), red (RD), and blue (BL), respectively. The polymer communities were identified as high-density polyethylene (HDPE), low-density polyethylene (LDPE), polypropylene (PP), polyethylene terephthalate (PET), polystyrene (PS), and nylon. The highest average MP density was identified in the basin of Killiyar (799 ± 0.09 pieces/kg) followed by Karamana River (671 ± 3.45 pieces/kg), indicating the closeness of the sampling station to the city center compared to Akkulam-Veli Lake (486 ± 58.55 pieces/kg). The majority of the sampling sites belonged to the slopy areas and came under the highly urbanized land category. A close association was observed between particle abundance and urban activity. The study foresees possible threats inflicted by MP abundance upon the area-wide hydro-biological system.