Microplastic sampling techniques in freshwaters and sediments: a review

Microplastics in riverine systems: Recommendations for standardized sampling, separation, digestion and characterization

Microplastic (MP) pollution has emerged as a global concern, prompting numerous studies on MP detection. Due to the remaining methodological challenges, it affects the accuracy and reliability of MP's impact assessment on river systems. To address this, the establishment of standardized operating protocols is crucial, encompassing sampling, separation, digestion, and characterization methods. This study evaluates the current tools used for identifying and quantifying MPs in riverine ecosystems, aiming to offer harmonized guidelines for future protocols. Recommendations include adopting a consistent format for reporting MP concentrations and providing improved information on sampling, separation, and digestion for enhanced cross-study comparisons. The importance of quality assurance and quality control is also discussed. Furthermore, we highlight unresolved issues, proposing avenues for further investigation. Suggestions encompass standardizing river sampling methods, optimizing technical steps and analysis processes, and enhancing the accuracy, reliability, and comparability of detection data to advance our understanding of MPs in river environments.

How much do we know about the microplastic distribution in the Mediterranean Sea: A comprehensive review

The Mediterranean Sea is one of the most heavily polluted regions. Here we comprehensively review the current state of microplastic pollution in the Mediterranean Sea and the Black Sea. A total of 284 studies published between 2012 and 2023 were analyzed, revealing a continuous increase in research efforts. Our review encompassed microplastic monitoring studies across five environmental matrices: the sea surface, water column, intertidal sediment, bottom sediment, and biota, with a predominant focus observed in biota-related studies with fish, molluscs, crustaceans, and echinoderms being the primary focus. The study found that species such as Mullus barbatus, Mytilus galloprovincialis, Nephrops norvegicus, and Holothuria tubulosa are frequently studied species. The review also emphasizes the lack of standardized methodologies across studies, which hampers the comparability of results and the synthesis of data. The findings of this study provide a critical evaluation of the current research landscape and identify significant knowledge gaps, particularly in the underrepresented southern Mediterranean and Black Sea regions, calling for more balanced research efforts and methodological consistency in future studies.

Monitoring of contamination by microplastics on sandy beaches at Vulcano Island (Sicily, Italy) by hyperspectral imaging

In this work, the monitoring and characterization of large microplastics (1-5 mm) collected from sandy beaches of Vulcano Island (Aeolian Islands, Sicily, Italy) were carried out for the first time. Microplastics were sampled from two beaches, "Gelso" and "Sabbie Nere," in three different time periods. The following characteristics of microplastic samples were assessed: quantity, distribution, categories, color, polymer type, size, and shape parameters. The polymers were identified using hyperspectral imaging, whereas an automatic image analysis approach was employed to determine microplastics' morphological and morphometrical attributes. Finally, the microplastic diversity integrated index was computed to obtain information on the potential emission sources of microplastics. It was found that the concentration of microplastics varies from 0.27 particles/kg_dw to 1.35 particles/kg_dw with fragment being the main collected category, with minor amount of pellet, foam, film, and filament. The predominant color of microplastics was by far white, followed by blue and yellow. The identified polymers were polyethylene and polypropylene followed by expanded polystyrene, polyamide, polystyrene, and polyethylene terephthalate. The morphological and morphometrical characterization highlighted a large variability for most size and shape parameters. Finally, the Microplastics Diversity Integrated Index results showed average indices compared to the literature, with higher values for the "Gelso" site (0.656), indicating a higher heterogeneity of sources, with respect to "Sabbie Nere" beach (0.530).

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.

Distribution, flux, and risk assessment of microplastics at the Anzali Wetland, Iran, and its tributaries

Microplastic pollution has raised significant concerns among scientific communities and society in recent years due to its increase and lesser-known effects on the environment. To improve the knowledge of microplastic pollution in freshwater, we investigated microplastics in Anzali Wetland, a Ramsar site in northern Iran, as well as its nine main entering rivers. The extracted microplastics were characterized via visual identification, SEM-EDX, and μ-Raman methods. Microplastics (size range: 50-5000 μm) were found in all water and sediment samples with concentration of fibrous particles as well as polypropylene and polyethylene polymers. The mean concentration of microplastics in bottom sediment and surface water samples of the wetland was 301 ± 222 particles∙kg-1 d.w. and 235 ± 115 particles∙m-3 (0.23 particles∙L-1), respectively. The microplastic concentration in the central and eastern parts of the wetland was higher than in other areas; however, the mean concentrations revealed homogeneity across the wetland area. Water properties (dissolved oxygen, pH, temperature, electrical conductivity, and salinity in water) did not affect the concentration of microplastic particles, though correlational analysis revealed a strong positive association between microplastic quantity and turbidity. There was a significant positive relationship between microplastic concentration and the percentage of clay in sediment samples. The quantity of microplastics in river water was higher than in wetland water, but the difference between the results was not significant. However, the quantity of microplastics in the river's littoral sediment was higher than in the bottom sediment of the wetland where the difference between the results was significant. Microplastic ecological risk assessment showed high potential ecological risk. The findings underscore the importance of effective management strategies and the implementation of policies to mitigate the negative impact of MP pollution on ecosystems and human health.

Evaluating the sources of microplastic contamination and quantifying its abundance in the Balu River, Dhaka, Bangladesh

Microplastics (MPs) are prevalent environmental pollutants due to their durable composition, extensive use, and improper disposal. Despite their widespread presence, rivers have received less attention in microplastic research than other water bodies. This study focused on investigating the origins, prevalence, spatial distribution, and physicochemical characteristics of microplastics in the surface waters of the Balu River, located in Dhaka, Bangladesh. Surface water samples were collected at six sampling sites of Balu River (each about 1-5 km apart) adjacent to the footwear industry, jute factory, textile mill, paper mill, agro and beverage factory, and cement plant. The study found that the average concentration of microplastics in the sampled water bodies was 102.5 ± 12.83 (items/l). Samples near the textile mill had the highest microplastic abundance (122 ± 18 items/l), while the cement plant had the lowest (58.5 ± 8 items/l). Analysis using a stereomicroscope revealed that fibers (29%), microplastics smaller than 100 µm (45%), and transparent microplastics (19%) were the most prevalent types observed in terms of shape, size, and color, respectively. Furthermore, scanning electron microscopy (SEM) observation suggested the potential for additional degradation of these microplastics into smaller particles, potentially reaching the nanoplastic scale. Additionally, Fourier transform infrared (FTIR) analysis identified 07 distinct polymer types among the microplastics: nylon (24%), polyvinyl chloride (19%), high-density polyethylene (17%), low-density polyethylene (14%), polystyrene (12%), polypropylene (7%), and nitrile (7%). The findings of this study serve as a crucial indicator of microplastic contamination, providing valuable insights into the sources and magnitude of microplastic pollution within the significant freshwater ecosystem of Balu River, Bangladesh, particularly focusing on its river systems.

Detection of microplastics in zebrafish housing systems: Can microplastic background contamination affect the final results of microplastic-related toxicological tests?

Concentrations of microplastics (MPs) were determined in three commonly used zebrafish housing systems to see if their levels could affect the final results of laboratory microplastic-related toxicology tests. MPs have received notable attention in the last few years, and their toxicology tests have also come to the fore. Zebrafish (Danio rerio), kept in fish housing systems, are widely used as models for MPs studies. Most of these systems contain a significant number of parts made of different polymers. As usage and amortization can erode these parts, MPs might appear in the keeping water or the fish body, which may represent a background load and possibly influence the results of microplastic-related toxicological tests. To take representative water samples from systems, two in-situ filtration techniques, a newly developed peristaltic pump-, and a jet pump-driven method were applied. The collected MP particles were analyzed with a Fourier-transform infrared microscope (detection limit 50 μm), and their possible origin was also investigated. The newly developed technique was more sufficient for sampling as it had a higher MPs recovery, especially in the smaller size range. Polyester, polyethylene and polypropylene were the most frequently detected polymers in the examined fish housing systems, the highest detected concentration was 0.31±0.12 particles/liter (0.22±0.16 μg/liter). These values are negligible compared to the literature data reporting enormously high applied MPs concentrations (104 - 2.21 × 108 particles/liter) during toxicology tests. The results also show that some detected MPs did not originate from the systems, their origin was presumed to be external.

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;1-15. © 2024 SETAC.

Harnessing Magnetic Nanoparticles for the Effective Removal of Micro- and Nanoplastics: A Critical Review

The spread of micro- (MPs) and nanoplastics (NPs) in the environment has become a significant environmental concern, necessitating effective removal strategies. In this comprehensive scientific review, we examine the use of magnetic nanoparticles (MNPs) as a promising technology for the removal of MPs and NPs from water. We first describe the issues of MPs and NPs and their impact on the environment and human health. Then, the fundamental principles of using MNPs for the removal of these pollutants will be presented, emphasizing that MNPs enable the selective binding and separation of MPs and NPs from water sources. Furthermore, we provide a short summary of various types of MNPs that have proven effective in the removal of MPs and NPs. These include ferromagnetic nanoparticles and MNPs coated with organic polymers, as well as nanocomposites and magnetic nanostructures. We also review their properties, such as magnetic saturation, size, shape, surface functionalization, and stability, and their influence on removal efficiency. Next, we describe different methods of utilizing MNPs for the removal of MPs and NPs. We discuss their advantages, limitations, and potential for further development in detail. In the final part of the review, we provide an overview of the existing studies and results demonstrating the effectiveness of using MNPs for the removal of MPs and NPs from water. We also address the challenges that need to be overcome, such as nanoparticle optimization, process scalability, and the removal and recycling of nanoparticles after the completion of the process. This comprehensive scientific review offers extensive insights into the use of MNPs for the removal of MPs and NPs from water. With improved understanding and the development of advanced materials and methods, this technology can play a crucial role in addressing the issues of MPs and NPs and preserving a clean and healthy environment. The novelty of this review article is the emphasis on MNPs for the removal of MPs and NPs from water and a detailed review of the advantages and disadvantages of various MNPs for the mentioned application. Additionally, a review of a large number of publications in this field is provided.

Microplastics in urban water systems, Tehran Metropolitan, Iran

Urban water systems are potential sources of secondary microplastics (MPs) as well as a distributor of MPs in the environment. In the present study, the presence of MPs in the urban water systems of the Tehran Metropolitan (Capital of Iran) was investigated. In addition, the probable relationship of MPs with different land uses (i.e., residential-commercial, forest, military, and highway) was assessed. The results showed that all parts of Tehran's urban water system in the study area were contaminated with MPs (107.1 ± 39, 37.8 ± 10.5, 48.3 ± 3.1, 46.9 ± 5.6, 59.4 ± 26.5, 1.7, 2.0 ± 0.6, 7.9 ± 1, 1.8 ± 0.2 particles/liter at the residential, integrated, military, forest, highway runoffs, drinking water, groundwater, seasonal river, and the effluent of the wastewater treatment plants; respectively). However, significant differences were found between different land uses. As expected, the residential runoff had the highest rate of MPs pollution, with 107.1 ± 39 particles/liter. According to the obtained results and our estimation, more than five million MPs/day can enter into the water bodies and soil of the study area through the wastewater treatment plants. While there are significant differences in MPs in the different land uses, our findings suggest that residential areas and highways need further attention in controlling the spread of MPs in urban areas.

Microplastics pollution in the Asian water tower: Source, environmental distribution and proposed mitigation strategy

Microplastics generated from fragmentation of leftover plastics and industrial waste has reached in the remotely located Asian water tower (AWT) region, the 3rd pole of earth and origin site of several freshwater rivers. The accumulation of microplastics in AWT ecosystem has potential to alter the climatic condition contributing in global warming and disturbing the biodiversity structural dynamics. The present paper provides a comprehensive critical discussion over quantitative assessment of microplastics in different ecosystems (i.e. river, lakes, sediment and snow or glacier) of AWT. The hydrodynamic fate and transport of microplastics and their ecological impact on hydromorphology and biodiversity of AWT has been exemplified. Furthermore, key challenges, perspectives and research directions are identified to mitigate microplastics associated problems. During survey, the coloured polyethylene and polyurethane fibers are the predominant microplastics found in most areas of AWT. These bio-accumulated MPs alter the rhizospheric community structure and deteriorate nitrogen fixation process in plants. Significance in climate change, MPs pollution is enhancing the emissions of greenhouse gases (NH3 by ∼34% and CH4 by ∼9%), contributing in global warming. Considering the seriousness of MPs pollution, this review study can enlighten the pathways to investigate the effect of MPs and to develop monitoring tools and sustainable remediation technologies with feasible regulatory strategies maintaining the natural significance of AWT region.

Understanding microplastic pollution of marine ecosystem: a review

Microplastics are emerging as prominent pollutants across the globe. Oceans are becoming major sinks for these pollutants, and their presence is widespread in coastal regions, oceanic surface waters, water column, and sediments. Studies have revealed that microplastics cause serious threats to the marine ecosystem as well as human beings. In the past few years, many research efforts have focused on studying different aspects relating to microplastic pollution of the oceans. This review summarizes sources, migration routes, and ill effects of marine microplastic pollution along with various conventional as well as advanced methods for microplastics analysis and control. However, various knowledge gaps in detection and analysis require attention in order to understand the sources and transport of microplastics, which is critical to deploying mitigation strategies at appropriate locations. Advanced removal methods and an integrated approach are necessary, including government policies and stringent regulations to control the release of plastics.

Microplastics in aquatic ecosystems of Africa: A comprehensive review and meta-analysis

Microplastic pollution is a global issue of great public concern. Africa is flagged to host some of the most polluted water bodies globally, but there is no enough information on the extent of microplastic contamination and the potential risks of microplastic pollution in African aquatic ecosystems. This meta-analysis has integrated data from published articles about microplastic pollution in African aquatic ecosystems. The data on the microplastic distribution and morphological characteristics in water, sediments and biota from African rivers, lakes, oceans and seas were extracted from 75 selected studies. Multivariate statistics were used to critically analyze the effects of sampling and detection methods, ecological risks, spatial distribution and similarity of microplastics in relation to the geographical distance between sampling sites. This study found that sampling methods have significant effect on abundance and morphological characteristics of microplastics and that African aquatic ecosystems are highly contaminated with microplastics compared to global data. The most prevalent colors were white, transparent and black, the most prevalent shapes were fibres and fragments, and the most available polymers were polypropylene (PP), polystyrene (PS) and polyethene terephthalate (PET). Microplastic polymers similarity decreased with an increase in geographical distance between sites. Risk levels of microplastics in African aquatic ecosystems were comparatively high, and more than 40 % of water and sediments showed highest level of ecological risk. This review provides recent information on the prevalence, distribution and risks of microplastics in African aquatic ecosystems.

Systematic CFD-based evaluation of physical factors influencing the spatiotemporal distribution patterns of microplastic particles in lakes

Spatiotemporal distribution patterns of microplastic (MP) particles in lakes hinge on both the physical conditions in the lake and particle properties. Using numerical simulations, we systematically investigated the influence of lake depth and bathymetry, wind and temperature conditions, MP particle release location and timing, as well as particle diameter (10, 20, and 50 μm). Our results indicate that maximum lake depth had the greatest effect on the residence time in the water column, as it determines the settling timescale and occurrence of hydrodynamic complexity such as density-driven flows in the lake. Increasing particle size from 10 to 20 and 50 μm also significantly reduced the residence time making particle size the factor with the second strongest effect on the residence time and, in turn, on the availability of MP particles for uptake by organisms. Changing bathymetry from a uniform to a non-uniform had a less pronounced effect on particle residence time compared to maximum depth and particle size. Release location, wind conditions, and release time had comparably little effect on particle behavior but became more important as MP particle size decreased. The release of the 10 μm MP particles in the deeper lakes with uniform bathymetry during summer with stable thermal stratification, resulted in a nearly month-long turnover phase in the fall in which both settling and rising of particles occurred simultaneously. This was caused by convective heat and water transport during this period. In these scenarios about 2.6 to 5.4 % of the released MP particles were held in or returned to the water layers near the lake surface. While acknowledging the dominant role of lake depth and MP particle size on the particle residence time, this study further emphasizes that it is ultimately a particular combination of different factors and their interactions that shape MP distribution patterns in lakes.

Microplastic pollution: a review of techniques to identify microplastics and their threats to the aquatic ecosystem

Microplastics (MPs), small synthetic particles, have emerged as perilous chemical pollutants in aquatic habitats, causing grave concerns about their disruptive effects on ecosystems. The fauna and flora inhabiting these specific environments consume these MPs, unwittingly introducing them into the intricate web of the food chain. In this comprehensive evaluation, the current methods of identifying MPs are amalgamated and their profound impacts on marine and freshwater ecosystems are discussed. There are many potential risks associated with MPs, including the dangers of ingestion and entanglement, as well as internal injuries and digestive obstructions, both marine and freshwater organisms. In this review, the merits and limitations of diverse identification techniques are discussed, including spanning chemical analysis, thermal identification, and spectroscopic imaging such as Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, and fluorescent microscopy. Additionally, it discusses the prevalence of MPs, the factors that affect their release into aquatic ecosystems, as well as their plausible impact on various aquatic ecosystems. Considering these disconcerting findings, it is imperative that appropriate measures should be taken to assess the potential risks of MP pollution, protect aquatic life and human health, and foster sustainable development.

Unveiling microplastics with hyperspectral Raman imaging: From macroscale observations to real-world applications

The widespread use of plastic materials, owing to their several advantageous properties, has resulted in a considerable increase in plastic consumption. Consequently, the production of primary and secondary microplastics has also increased. To identify, categorize, and quantify microplastics, several analytical methods, such as thermal analysis and spectroscopic methods, have been developed. They generally offer little insight into the size and shape of microplastics, require time-consuming sample preparation and classification, and are susceptible to background interference. Herein, we created a macroscale hyperspectral Raman method to quickly quantify and characterize large volumes of plastics. Using this approach, we successfully obtained Raman spectra of five different types of microplastics scattered over an area of 12.4 mm × 12.4 mm within just 550 s and perfectly classified these microplastics using a machine learning method. Additionally, we demonstrated that our system is effective for obtaining Raman spectra, even when the microplastics are suspended in aquatic environments or bound to metal-mesh nets. These results highlight the considerable potential of our proposed method for real-world applications.

Harnessing fungal bio-electricity: a promising path to a cleaner environment

Integrating fungi into fuel cell systems presents a promising opportunity to address environmental pollution while simultaneously generating energy. This review explores the innovative concept of constructing wetlands as fuel cells for pollutant degradation, offering a practical and eco-friendly solution to pollution challenges. Fungi possess unique capabilities in producing power, fuel, and electricity through metabolic processes, drawing significant interest for applications in remediation and degradation. Limited data exist on fungi's ability to generate electricity during catalytic reactions involving various enzymes, especially while remediating pollutants. Certain species, such as Trametes versicolor, Ganoderma lucidum, Galactomyces reessii, Aspergillus spp., Kluyveromyce smarxianus, and Hansenula anomala, have been reported to generate electricity at 1200 mW/m3, 207 mW/m2, 1,163 mW/m3, 438 mW/m3, 850,000 mW/m3, and 2,900 mW/m3, respectively. Despite the eco-friendly potential compared to conventional methods, fungi's role remains largely unexplored. This review delves into fungi's exceptional potential as fuel cell catalysts, serving as anodic or cathodic agents to mitigate land, air, and water pollutants while simultaneously producing fuel and power. Applications cover a wide range of tasks, and the innovative concept of wetlands designed as fuel cells for pollutant degradation is discussed. Cost-effectiveness may vary depending on specific contexts and applications. Fungal fuel cells (FFCs) offer a versatile and innovative solution to global challenges, addressing the increasing demand for alternative bioenergy production amid population growth and expanding industrial activities. The mechanistic approach of fungal enzymes via microbial combinations and electrochemical fungal systems facilitates the oxidation of organic substrates, oxygen reduction, and ion exchange membrane orchestration of essential reactions. Fungal laccase plays a crucial role in pollutant removal and monitoring environmental contaminants. Fungal consortiums show remarkable potential in fine-tuning FFC performance, impacting both power generation and pollutant degradation. Beyond energy generation, fungal cells effectively remove pollutants. Overall, FFCs present a promising avenue to address energy needs and mitigate pollutants simultaneously.

Urban tropical freshwater ponds as microplastics hotspots-insight on abundance and characteristics using an improved sampling technique

This study elucidates the distribution and characteristics of microplastics (MPs) in 20 tropical freshwater ponds, located in the urban settlement of Raipur city in state of Chhattisgarh, India. The ponds were divided into 4 groups based on the habitat types to understand the influence of land use patterns and human activity on the distribution of MPs. Here, we provide an improved sampling technique that is economical, traditional, indigenous, independent of vessels or structures, and replicable for smaller waterbodies. The efficiency of the proposed method is closer to the traditional boat-based net sampling technique. MPs are ubiquitous in surface water samples of all 20 ponds. The average abundance of MPs was 2.52 ± 1.28 particles/L for bucket samples and 2.93 ± 1.34 particles/L for net samples. Among extracted MPs, fragments, films, and foams were dominant. MPs within size class 1 mm to 500 μm were prevailing for both bucket samples and tube-net samples. Color-wise, white/transparent and black MPs were abundant in both types of samples while the majority of MPs were polyethylene and polystyrene. The tube-net sampling method is economical and replicable and provides comparable results. This can help study MPs distribution in smaller inland waterbodies where boats and structures are not readily available to conduct net sampling. We provide the first insight into the distribution of MPs in urban ponds, and the results can be used to determine the ubiquity of MPs in urban ponds located in different regions of the subcontinent.

Investigations on microplastic infiltration within natural riverbed sediments

Several studies focused on the role of rivers as vectors of microplastics (MPs) towards the sea. It is well known that during their path through the fluvial environment, MPs interact with riverbed sediments; however, the main factors impacting the mobility of MPs within the upper part of the hyporheic zone are not clear yet. The present work investigates the role of different sediment size layers in affecting the mobility of the most common MP (Polyethylene terephthalate - PET - spheres, PET 3D-ellipsoids, polystyrene - PS - fragments and polyamide - PA - fibers) within sediment porous media under different hydraulic loads (HL) and time scales (t) conditions. Results indicated the relationship between the characteristic MP diameter and that of the grains as the main parameter for the MP infiltration into the sediment layer. The maximum infiltration depth was found to not depend on HL and t. However, HL was able to influence the percentage of MPs penetrating the superficial layer and their distribution within the first 10-15 cm of the sediment layer. None of the MPs were found at depths >20-25 cm, where only PET spheres were detected. Starting from the suffusion theory, a model able to predict the MP maximum infiltration depth in the range of parameter values was provided. The outcome indicates the importance of considering geometrical and hydrodynamic aspects of the riverbed sediment layer to better characterize the spatial and temporal scales of MP transport in freshwater environments.

Electricity generation and oxidoreductase potential during dye discoloration by laccase-producing Ganoderma gibbosum in fungal fuel cell

Color chemicals contaminate pure water constantly discharged from different points and non-point sources. Physical and chemical techniques have certain limitations and complexities for bioenergy production, which motivated the search for a novel sustainable production approaches during dye wastewater treatment. The emerging environmental problem of dye decolorization has attracted scientist's attention to a new, cheap, and economical way to treat dye wastewater and power production via fungal fuel cells. Ganoderma gibbosum was fitted in the cathodic region with laccase secretion in the fuel cell. At the same time, dye water was placed in the anodic region to move electrons and produce power. This study treated wastewater using the oxidoreductase enzymes released extracellularly from Ganoderma gibbosum for dye Remazol Brilliant Blue R (RBBR) degradation via fungal-based fuel cell. The maximum power density of 14.18 mW/m2 and the maximum current density of 35 mA/m2 were shown by the concentration of 5 ppm during maximum laccase activity and decolorization of RBBR. The laccase catalysts have gained considerable attention because of eco-friendly and alternative easy handling approaches to chemical methods. Fungal Fuel Cells (FFCs) are efficiently used in dye treatment and electricity production. This article also highlighted the construction of fungal catalytic cells and the enzymatic performance of fungal species in energy production during dye water treatment.

Impact of flooding on microplastic abundance and distribution in freshwater environment: a review

Due to smaller particle size (0.1 µm-5 mm), non-biodegradable or slowly degradable nature, and high accumulation capacity in the environment, microplastics are becoming a cause of concern throughout the globe. The abundance and distribution of microplastics in aquatic compartments are strongly influenced by various natural and anthropogenic variables. Hydrodynamic conditions like flood events, caused due to extreme precipitation, accelerate the transport and settlement of microplastics in freshwater bodies. This review highlights the current literature which focuses on the effect of flooding on microplastic abundance, characterization, and distribution in freshwater environments worldwide. However, only limited research papers are identified through focused literature search, as this area of research is relatively new. Most of the studies reported increased and decreased abundance of microplastics in water and sediment samples, respectively, during post-flooding period with the exception of few studies. We also evaluate the post-flooding abundances of different morphological shape and polymer type of microplastics. Fragments, fibers, beads, and film were the most frequently reported microplastic shape and polystyrene, and polyethylene was the dominant polymer type found in freshwater environments. Future research should focus on more advanced techniques to understand microplastic fluxes under flood condition and the dominance of various natural and human-induced factors over one another in determining microplastic abundance. This will further enhance to mitigate microplastic pollution in freshwater environments.

Microplastic contamination in Indian rural and urban lacustrine ecosystems

This study investigates the microplastics (MPs) pollution of the lacustrine ecosystems of Tamil Nadu, South India. It examines the seasonal distribution, characteristics and morphology of MPs and assesses the risk posed by MPs pollution. MPs abundance in the 39 rural and urban lakes studied varies from 16 ± 2.69 to 118.17 ± 22.17 items/L (water) and 19.50 ± 4.75 to 156.23 ± 36.41 items/kg (sediment). The water and sediment of urban lakes show average MPs abundances of 88.06 items/L and 115.24 items/kg respectively, while the rural lakes exhibit average MPs abundances of 42.98 items/L and 53.29 items/kg. The results demonstrate that study areas with more residential and urban centers with higher population density and larger discharge of sewage have greater MP abundance. Urban zones have greater MP diversity integrated index (MPDII = 0.73) than rural zones (MPDII = 0.59). Fibres are the dominant group and polyethylene and polypropylene are the most commonly found polymers, possibly gaining entry through land-based plastic litter and urban activities in this region. The weathering index values, 50 % of MPs exhibit high degree of oxidation (WI >0.31) with an age of >10 years. SEM-EDAX results reveal that the weathered MPs from urban lakes have a wider variety of metal elements (Al, Cr, Mn, Co, Ni, Cu, Zn, As, Sr, Hg, Pb and Cd) than those from rural lakes (Na, Cl, Si, Mg, Al, Cu). Though PLI shows low risk (<10) in terms of abundance, PHI reflects pollution status III (10-100) and IV (100-1000) in rural areas and IV and V (>1000) in urban areas based on the toxicity score of the polymer. Ecological risk assessment shows minor risks (<150) at present. The assessment indicates the risk posed by the MPs to the lakes studied and emphasizes the necessity for best MP management practices in future.

Scavenging microplastics and heavy metals from water using jujube waste-derived biochar in fixed-bed column trials

Extensive production and utilization of plastic products have resulted in the generation of microplastics (MPs), subsequently polluting the environment. The efficiency of biochars (BCs) derived from jujube (Ziziphus jujube L.) biomass (300 °C and 700 °C) for nylon (NYL) and polyethylene (PE) removal from contaminated water was explored in fixed-bed column trials. The optimum pH for the removal of both MPs was found 7. Both of the produced biochars demonstrated >99% removal of the MPs, while the sand filter exhibited a maximum of 78% removal of MPs. BC produced at 700 °C (BC700) showed 33-fold higher MPs retention, while BC produced at 300 °C (BC300) exhibited 20-fold higher retention, as compared to sand filters, indicating the higher efficiency of BC produced at higher pyrolysis temperature. Entrapment into the pores, entanglement with flaky structures of the BCs, and electrostatics interactions were the major mechanism for MPs retention in BCs. The efficiency of MPs-amended BCs was further explored for the removal of Pb(II) and Cd(II) in fixed-bed column trials. BC700 amended with PE and NYL exhibited the highest 50% breakthrough time (2114.23 and 2024.61 min, respectively, for Pb(II) removal and 2107.92 and 1965.19 min, respectively, for Cd(II) removal), as compared to sand filters (38.07 and 60.49 min for Pb(II) and Cd(II) removal, respectively). Thomas model predicted highest adsorption capacity was exhibited by BC700 amended with PE (584.34 and 552.80 mg g-1, for Pb(II) and Cd(II) removal, respectively), followed by BC700 amended with NYL (557.65 and 210.59 mg g-1 for Pb(II) and Cd(II) removal, respectively). Therefore, jujube waste-derived BCs could be used as efficient adsorbents to remove PE and NYL from contaminated water, while MPs-loaded BCs can further be utilized for higher adsorption of Pb(II) and Cd(II) from contaminated aqueous media. These findings suggest that BC could be used as an efficient adsorbent to remove the co-existing MPs-metals ions from the environment on a sustainable basis.

Insight into the marine microplastic abundance and distribution in ship cooling systems

Microplastics (MPs) are becoming widely recognized as one of many global environmental issues. Although recently, it has been suggested that marine plastics may affect a ship's operation, the presence of MPs in a ship's cooling system has not received significant attention. In this study, samples of 40 L each were taken from each of the five main pipes (sea chest (SC), ejector pump (EP), main engine jacket freshwater pump (MJFP), main engine jacket freshwater cooler (MJFC), and expansion tank (ET)) in each season (February, May, July, October 2021) to identify and characterize MPs in the five main pipes of the ship cooling system from the training ship Hanbada, Korea Maritime and Ocean University. As a result of FTIR analysis, the total MP abundance was 24,100 particles/m³ in the cooling system of the ship. MP concentrations were observed to be higher (p < 0.05) in winter and spring (dry season: 1578 ± 604 particles/m³) than in summer and autumn (wet season: 990 ± 390 particles/m³). In addition, the MP concentration in the seawater cooling system (SCS) (1509 ± 553 particle/m³) was slightly higher (p > 0.05) than that in the freshwater cooling system (FCS) (1093 ± 546 particles/m³). Compared to previous studies, it was confirmed that the quantitative amount of MPs on board was similar to or slightly less than the concentration of MPs investigated along the coast of Korea (1736 particles/m³). To identify the chemical composition of MPs, an optical microscope and FTIR analysis was carried out, and PE (polyethylene), PP (polypropylene), and PET (polyethylene terephthalate) were identified as major chemicals in all samples. MPs in the form of fibers and fragments accounted for approximately 95% of the total. This study provided evidence of MP contamination in the main pipe in the cooling system of the ship. These findings confirm that marine MPs existing in seawater may have flowed into the ship's cooling system, and it is necessary to understand the effect of marine MPs on the ship's engine and cooling system through continuous monitoring.

Nowhere to go! Microplastic Abundances in Freshwater Fishes Living Near Wastewater Plants

Microplastic presence in aquatic environments is a major problem globally. This study quantified microplastic abundances in fish species across two systems in South Africa around wastewater treatment works. Fish (n=163) were examined for microplastic on gills and in gastrointestinal tracts. Microplastic levels were generally low during the cool-dry season (mean 11.0 - 34.0 particles per fish taxon), and high during the hot-wet season (mean 10.0 - 119.0 particles per fish taxon). The microplastic concentrations per fish were similar between these systems, with downstream of wastewater treatment plants having high microplastic abundances. Although benthopelagic feeders were dominant, pelagic feeders had high microplastic abundances (range 20-119 particles), followed by benthopelagic (range 10-110 particles) and demersal (22 particles) feeders. Multiple regression analysis revealed a significant positive relationship between fish standard length and total microplastic levels, which suggests fish consume more microplastics due to increased food demand as a result of growth.

Recent advances in micro (nano) plastics in the environment: Distribution, health risks, challenges and future prospects

Environmental micro(nano)plastics have become a significant global pollution problem due to the widespread use of plastic products. In this review, we summarized the latest research advances on micro(nano)plastics in the environment, including their distribution, health risks, challenges, and future prospect. Micro(nano)plastics have been found in a variety of environmental media, such as the atmosphere, water bodies, sediment, and especially marine systems, even in remote places like Antarctica, mountain tops, and the deep sea. The accumulation of micro(nano)plastics in organisms or humans through ingestion or other passive ways poses a series of negative impacts on metabolism, immune function, and health. Moreover, due to their large specific surface area, micro(nano)plastics can also adsorb other pollutants, causing even more serious effects on animal and human health. Despite the significant health risks posed by micro(nano)plastics, there are limitations in the methods used to measure their dispersion in the environment and their potential health risks to organisms. Therefore, further research is needed to fully understand these risks and their impacts on the environment and human health. Taken together, the challenges of micro(nano)plastics analysis in the environment and organisms must be addressed, and future research prospects need to be identified. Governments and individuals must take action to reduce plastic waste and minimize the negative impact of micro(nano)plastics on the environment and human health.

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

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

Lakes with or without urbanization along their coasts had similar level of microplastic contamination, but significant differences were seen between sampling methods

The influence of sampling method on microplastic (MP) quantification and the impact of population density on the levels of MP contamination in surface waters from Patagonian lakes were investigated. Six lakes located in Northern Patagonia (Argentina) were studied using two different sampling protocols widely reported in the literature: water collected in glass bottles vs. water collected using a 50 μm mesh size net. To assess the influence of population density on MP contamination, lakes with urbanization at shores (Nahuel Huapi, Gutierrez and Moreno) and lakes without urbanization on their shores (Espejo, Espejo Chico and Mascardi) were considered. We identified contamination with secondary MP at all the freshwater lakes studied, with predominance (>90 %) of textile-based microfibers (MF). Remarkably the levels of contamination were similar in all the lakes, independently of whether they were impacted by urbanization along their coasts or not, which supports the notion that there is atmospheric transport of MP. The greatest variability found was among sampling methods, with differences above of three orders magnitude. Samples collected directly in 1-l bottles had an average of 5257 MP/m³ in comparison to 1.57 MP/m³ in the samples that were collected with a 50 μm net. Interestingly, Nahuel Huapi lake samples collected with bottles where the WWTP discharges effluents were significantly more contaminated (SD 9400 ± 4351 MP/MF per m³) than samples collected 5 km west of the plant (2100 ± 1197 MP/MF per m³). Results highlight the significance of textile microfibers as microplastic contaminants of freshwater, and the need to address mesh size when looking for textile microfibers and to develop standardized sampling protocols to make studies on freshwater MF contamination comparable.

Research status and prospects of microplastic pollution in lakes

As an emerging pollutant, microplastics have attracted widespread concern around the world. Research on microplastics was first conducted in oceans, and in recent years, inland water, especially lakes, has gradually become a hot spot. This paper systematically reviews the sampling, separation, purification, and identification technologies used to assess microplastics in lakes and summarizes the occurrence of lake microplastics worldwide. The results show that microplastics are widespread in lake water and sediment. There are obvious geographical differences in the occurrence of microplastics. The abundance of microplastics in different lakes varies greatly. The forms are mostly fibrous and fragments, and the main polymers are polypropylene (PP) and polyethylene (PE). Previous papers have failed to comment in as much detail on the microplastic sampling techniques employed within lake systems. The sampling and analysis methods are critical to accurately evaluating contamination results. Due to the widespread presence of microplastics and the lack of uniform standards, there are various sampling methods. Trawls and grabs are most widely used in the sampling of lake water bodies and sediment, and sodium chloride and hydrogen peroxide are the most widely used media for flotation and digestion, respectively. In the future, it will be critical to establish unified standards for lake microplastic sampling and analysis technology, further explore the migration mechanism of microplastics in lake systems, and pay attention to the impact of microplastics on lake ecosystems.

Occurrence and distribution of microplastics in wetlands

Presence of microplastic particles has been reported in all over the world, even in remote areas with no human activities. Wetlands are important transitional areas between terrestrial and aquatic systems. However, microplastic pollution in wetlands is less studied than other aquatic ecosystems. In this review, documented researches about microplastic occurrence and distribution in different components of wetland systems (except constructed wetlands) were investigated. In this regard, all available articles from different science databases with the keywords microplastic, wetland and lagoon in title were examined and results were proposed by text, table and diagram, after standardization of data express units. Based on results, wetland ecosystems are prone to microplastic pollution. Based on particle properties, PE/PP and fiber/fragment were the most dominant reported chemical composition and particle shapes, respectively.

Biotechnological methods to remove microplastics: a review

Microplastics pollution is major threat to ecosystems and is impacting abiotic and biotic components. Microplastics are diverse and highly complex contaminants that transport other contaminants and microbes. Current methods to remove microplastics include biodegradation, incineration, landfilling, and recycling. Here we review microplastics with focus on sources, toxicity, and biodegradation. We discuss the role of algae, fungi, bacteria in the biodegradation, and we present biotechnological methods to enhance degradation, e.g., gene editing tools and bioinformatics.

Investigating the evolution of the technologies for collecting microplastics

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

Characteristics of (micro)plastic transport in the upper reaches of the Yangtze River

Many studies focus on the transport of plastic from rivers to oceans while little attention was paid to the plastic transport in the upper reaches of rivers. Transport process of plastic from upstream to downstream in the whole river basin scale is still poorly understood. In this work, five sections in the upper reaches of the Yangtze River were investigated to characterize the features of plastic transport. Plastic abundance and flux were 293 to 156,667 n/m³ and 1.2 to 34,711 g/s, respectively. Plastic flux peaked at or right after the first flood peak in most sections, but plastic abundance was the highest in the normal or low water period. The first flood peak caused a temporary rise of plastic flux that last a short duration. Transport of plastic was not limited to water surface, and the Three Gorges Dam showed a peak elimination effect on plastic transport. Annual discharge of plastic was 1392 to 9532 tons and 6.2 × 10¹⁴ to 175 × 10¹⁴ particles at different sections. An increasing trend was observed for both plastic mass and quantity going downstream. Results showed that river plastic flux is highly variable and influenced by the dam, which should be considered in future to develop better monitoring strategies and to further improve the model.

Analytical methods for microplastics in the environment: a review

Microplastic pollution is a recently discovered threat to ecosystems requiring the development of new analytical methods. Here, we review classical and advanced methods for microplastic analysis. Methods include visual analysis, laser diffraction particle, dynamic light scattering, scanning electron microscopy, Fourier-transform infrared spectroscopy, Raman spectroscopy, thermal analysis, mass spectrometry, aptamer and in vitro selection, and flow cytometry.

Microplastic in the Baltic Sea: A review of distribution processes, sources, analysis methods and regulatory policies

Microplastics pollution is an issue of great concern for scientists, governmental bodies, ecological organisations, and the general public. Microplastics pollution is widespread and is a great environmental problem on account of its potential toxicity for marine biota and human health. Today, almost all the world's seas and oceans are polluted with microplastics. The Baltic Sea is a semi-enclosed reservoir of brackish water and is a hotspot for contamination in terms of eutrophication and the presence of organic matter. Microplastics are quite intense, based on data from studies of marine litter and microplastics in the Baltic Sea. The number of microplastics in the Baltic Sea water is 0.07-3300 particles/m³, and in sediments 0-10179 particles/kg. These amounts prove that the waters and sediments of the Baltic Sea are heavily contaminated with microplastics. This article provides a comprehensive review of the microplastic origins and transport routes to the Baltic Sea. The data is presented as the concentration of microplastics in surface waters, sediments, and sea sand. The extraction methods used and the microplastics techniques are also presented. The possibilities and limitations of water and sediment sampling methods for microplastics determination were summarised, taking into account sampling tools, volume and depth. Extraction, separation, filtration, and visual sorting are outlined as sample preparation techniques for microplastic analysis. This review also focuses on the problems of obtaining data relevant to the development of the mathematical models necessary to monitor trends in the spread of microplastics in the Baltic Sea. Finally, several important laws and policies, which are in place in the Baltic States to control and manage microplastic pollution in the region, are highlighted.

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

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

Unraveling microplastics removal in wastewater treatment plant: A comparative study of two wastewater treatment plants in Thailand

Wastewater treatment plants (WWTPs) are considered as a problematic pathway for microplastics (MPs) entering the oceans. This study compares the efficiency of MP removal in two different WWTPs (A₁ and A₂) with a conventional treatment system located in Bangkok, Thailand. WWTP-A₂ is equipped with a pilot-scale ultrafiltration (UF) as a final polishing step. The number of MPs in the influent entering A₁ and A₂ was 16.55 ± 9.92 and 77.00 ± 7.21 MP/L, respectively. The average of 3.52 ± 1.43 and 10.67 ± 3.51 particles per L was found in the effluent discharged from A₁ and A₂, respectively, to nearby canals. The removal efficiency of WWTP-A₂ built as a closed underground system was shown to be up to 86.14% which is more efficient than the conventional WWTP (A₁). MPs were subsequently removed by a UF unit which resulted in a removal efficiency of 96.97%. However, when a large volume of treated wastewater volume is considered, a high concentration of MPs is discharged daily with the final effluent if the efficiency remains the same. The size fraction of 0.5-0.05 mm contributed to the largest proportion of MPs, and fibers were detected as the dominant group at both study sites. Results from a Fourier Transform Infrared Spectroscopy (FT-IR) confirmed that most fibers were polyethylene terephthalate (PET) derived from clothes. MPs retained in the sludge ranged from 2.63 × 10⁴ to 4.74 × 10⁴ particles per kilogram of dry sludge. A significant number of MPs can spread further to the environment by soil application. The results of the study indicate that the design of WWTPs and the addition of advanced tertiary treatment can improve MP removal efficiency of a WWTP. Moreover, the absence of a primary sedimentation tank in both treatment plants may influence the removal efficiency.

Good field practice and hydrogeological knowledge are essential to determine reliable concentrations of microplastics in groundwater

There are some weaknesses in the methodology of original paper "Informal landfill contributes to the pollution of microplastic in the surrounding environment" published in Environmental Pollution. We commented on the groundwater sampling procedure that affect the calculated concentrations of microplastics in groundwater. Important information related to the description of sampling wells, informal landfill, and the exact description of sample collection method are missing. In addition, significant data related to the groundwater like water level, flow direction, and velocity have been skipped, which are fundamental in groundwater related studies. There should be a clear diagram of landfill location and sampling wells in the landfill, for appropriate understanding of microplastics (MPs) pollution in surrounding environment of a landfill.

Fugitive release and influencing factors of microplastics in urbanized watersheds: A case study of the central area of Suzhou City

Urban areas are greatly affected by human activities that may result in the release of microplastics. Fugitive release of microplastics is the unorganized discharge of microplastics produced during plastic manufacturing and use. The microplastics enter the environment in a variety of ways. To investigate fugitively released microplastics and identify the major influencing factors in urban watersheds, the central area of Suzhou city was selected as a case study. This area has a dense network of canals without sources of organized release. The results show that the microplastic abundance in the urban canal of the area ranged from 8.29 to 40.63 particles L^-1, with a mean of 14.75 ± 3.95 particles L^-1. To better understand the relationship between microplastics and human activities, the main influencing factors, including water quality, water-related activities, dwelling type, urban landscaping, trash collection and land use type, were assessed. Water quality was not correlated with microplastic distribution in the urban watershed, as it is in larger watersheds. Water-related activities caused elevated fugitive release of microplastics. The abundance of microplastics discharged into the water environment in modern communities was significantly less than that discharged in an area of traditional residences. Traffic activities contributed to microplastic release, while urban landscaping physically blocked microplastics from flowing into urban waterbodies to some extent. Trash collection did not reduce the abundance of microplastic particles in the water, despite its ability to remove other types of plastic waste. The results also suggest that the contributions of different land use types to the abundance of microplastics in urban areas from highest to lowest were as follows: tourist districts > commercial areas > public areas > residential areas > roads. Moreover, fugitive release is an important source to be considered in future research on urban microplastic management. The renewal of urban construction to mitigate the influence of human activities on water ecology may play a positive role in controlling the fugitive release of microplastics.

Transport of Microplastics in Shore Substrates over Tidal Cycles: Roles of Polymer Characteristics and Environmental Factors

Tidal zones providing habitats are particularly vulnerable to microplastic (MP) pollution. In this study, the effects of tidal cycles on the transport of MPs (4-6 μm polyethylene, PE1; 125 μm polyethylene, PE2; and 5-6 μm polytetrafluoroethylene, PFTE) in porous media combined with various environmental and MPs properties were systemically investigated. The results indicated that smaller substrate sizes exhibited higher retention percentages compared to those of larger substrate sizes under different tidal cycles. In terms of the size of MPs, a larger size (same density) was found to result in enhanced retention of MPs in the column. As the number of tidal cycles increased, although the transport of MPs from the substrate to the water phase was enhanced, PE1 was washed out more with the change in water level, compared to PTFE. Additionally, more MPs were retained in the column with the increase of salinity and the decrease of flow velocity under the same tidal cycles. Ultraviolet and seawater aged PE1 showed enhanced transport, while aged PTFE showed enhanced retention under the same tidal cycles. These results can help understand the MP behaviors in the shoreline environment and provide support for future cleanup and sampling in tidal zones.

Occurrence, toxicity and remediation of polyethylene terephthalate plastics. A review

Polyethylene terephthalate is a common plastic in many products such as viscose rayon for clothing, and packaging material in the food and beverage industries. Polyethylene terephthalate has beneficial properties such as light weight, high tensile strength, transparency and gas barrier. Nonetheless, there is actually increasing concern about plastic pollution and toxicity. Here we review the properties, occurrence, toxicity, remediation and analysis of polyethylene terephthalate as macroplastic, mesoplastic, microplastic and nanoplastic. Polyethylene terephthalate occurs in groundwater, drinking water, soils and sediments. Plastic uptake by humans induces diseases such as reducing migration and proliferation of human mesenchymal stem cells of bone marrow and endothelial progenitor cells. Polyethylene terephthalate can be degraded by physical, chemical and biological methods.

Innovations in applications and prospects of bioplastics and biopolymers: a review

Non-biodegradable plastics are continually amassing landfills and oceans worldwide while creating severe environmental issues and hazards to animal and human health. Plastic pollution has resulted in the death of millions of seabirds and aquatic animals. The worldwide production of plastics in 2020 has increased by 36% since 2010. This has generated significant interest in bioplastics to supplement global plastic demands. Bioplastics have several advantages over conventional plastics in terms of biodegradability, low carbon footprint, energy efficiency, versatility, unique mechanical and thermal characteristics, and societal acceptance. Bioplastics have huge potential to replace petroleum-based plastics in a wide range of industries from automobiles to biomedical applications. Here we review bioplastic polymers such as polyhydroxyalkanoate, polylactic acid, poly-3-hydroxybutyrate, polyamide 11, and polyhydroxyurethanes; and cellulose-based, starch-based, protein-based and lipid-based biopolymers. We discuss economic benefits, market scenarios, chemistry and applications of bioplastic polymers.

Microplastics in mangroves and coral reef ecosystems: a review

Microplastic pollution has recently been identified as a major issue for the health of ecosystems. Microplastics have typically sizes of less than 5 mm and occur in various forms, such as pellets, fibres, fragments, films, and granules. Mangroves and coral reefs are sensitive and restricted ecosystems that provide free ecological services such as coastal protection, maintaining natural cycles, hotspots of biodiversity and economically valuable goods. However, urbanization and industrial activities have started contaminating even these preserved ecosystems. Here we review sources, occurrence, and toxicity of microplastics in the trophic levels of mangrove and coral reef ecosystems. We present detection methods, such as microscopic identification and spectroscopy. We discuss mitigating measures that prevent the entry of microplastics into the marine environment.