Microplastic distribution in the surface water and sediment of the Ergene River

Comprehensive review of ecological risks and toxicity mechanisms of microplastics in freshwater: Focus on zebrafish as a model organism

Zebrafish, as a model organism, exhibit high sensitivity to environmental pollutants and has been widely used in microplastics (MPs) toxicology studies. However, the mechanisms underlying MPs' effects on zebrafish have yet to be comprehensively summarized. This review systematically explores the sources, pollution status of freshwater MPs and their biological toxicity mechanisms using zebrafish as a model organism. This analysis reveals that the primary sources of MPs include sediment release, natural degradation of plastic products, and precipitation-mediated transport. Freshwater MPs predominantly comprise of polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), polystyrene (PS), and polyvinyl chloride (PVC). These MPs typically appear transparent, white, black, or blue, and predominantly exist as fibers, films, fragments, foams, and particles. The concentration, size, shape, type, aging status, and loading capacity of MPs can induce developmental malformations in zebrafish embryos, including pericardial and yolk sac edema. In adult zebrafish, MPs cause intestinal injuries characterized by increased permeability, impaired barrier function, and microbiota dysbiosis. MPs exposure also induces behavioral abnormalities such as reduced locomotion and anxiety-like responses, while simultaneously provoking oxidative stress and immune-inflammatory reactions. The physical mechanism of MPs-induced toxicity in zebrafish involves particle accumulation and tissue abrasion. In contrast, physiological and molecular mechanisms encompass interactions between MPs' surface functional groups and biological tissues, alterations in oxidative stress markers, enzymatic activity and cytokine profiles, and modulation of gene expression patterns. This review synthesizes current knowledge on the ecological risks of freshwater MP pollution and its toxicological impacts on zebrafish, thereby providing a comprehensive framework for understanding MP toxicity mechanisms.

Spatio-temporal distribution of microplastics in surface water of typical urban rivers in North China, risk assessment and influencing factors

Urban rivers serve as primary receivers and transporters of microplastics. In this study, the spatio-temporal distribution of microplastics in the surface waters of the Zhang River and Fuyang River, which are representative urban rivers in North China, was investigated. The risk evaluation and influencing factors were also analyzed. The results indicated that the average abundance of microplastics in the surface waters of the Zhang River was higher during the dry season, while the average abundance in the Fuyang River was lower than that observed in the Zhang River during the wet season. Furthermore, the abundance of microplastics exhibited an increasing trend from upstream to downstream. The predominant polymer types of microplastics identified are polyethylene (PE) and polypropylene (PP), with the majority being blue fibers 0-2 mm in size. In comparison to the Zhang River, the Fuyang River exhibits a higher diversity index of microplastics, with more varied and complex sources attributed to anthropogenic activities. The risk of microplastic pollution in the Zhang and Fuyang rivers was found to increase downstream. The spatial distribution of microplastics is influenced by both natural conditions and anthropogenic activities, with upstream areas dominated by natural factors and downstream areas dominated by human activities. This study provides a reference for understanding microplastic pollution levels and sources in urban rivers of Northern China.

Source apportionment and risk assessment of microplastics in the sediments of the Dan river based on APCS-MLR model

Microplastic pollution is becoming a global concern, and tracing its source is essential for effective prevention and control. Therefore, this study aimed to investigate the microplastics in the sediments of the Dan River in China to assess the pollution sources and ecological risks. The results showed that the microplastic abundance ranged from 20 to 2220 items·kg-1, with polymer composition primarily composed of polypropylene (PP;49.5 %) and polyethylene (PE;15.5 %) in the sediments. Quantitative source analysis using APCS-MLR (absolute principal component score-multiple linear regression) model revealed that, microplastics pollution from two sources: a mixed input from fishery and agricultural activities (65.17 %) and wastewater discharge from laundry and care products (34.83 %). Although overall pollution levels were low, a subset of microplastics with high hazard scores posed potential threats to ecological and environmental security at specific local sites. This study validates the applicability of the APCS-MLR model for microplastics source apportionment and provides a novel methodology for tracing pollution sources.

Machine Learning Advancements and Strategies in Microplastic and Nanoplastic Detection

Microplastics (MPs) and nanoplastics (NPs) present formidable global environmental challenges with serious risks to human health and ecosystem sustainability. Despite their significance, the accurate assessment of environmental MP and NP pollution remains hindered by limitations in existing detection technologies, such as low resolution, substantial data volumes, and prolonged imaging times. Machine learning (ML) provides a promising pathway to overcome these challenges by enabling efficient data processing and complex pattern recognition. This systematic Review aims to address these gaps by examining the role of ML techniques combined with spectroscopy in improving the detection and characterization of NPs. We focused on the application of ML and key tools in MP and NP detection, categorizing the literature into key aspects: (1) Developing tailored strategies for constructing ML models to optimize plastic detection while expanding monitoring capabilities. Emphasis is placed on harnessing the unique molecular fingerprinting capabilities offered by spectroscopy, including both infrared (IR) and Raman spectra. (2) Providing an in-depth analysis of the challenges and issues encountered by current ML approaches for NP detection. This Review highlights the critical role of ML in advancing environmental monitoring and improving our further, deeper investigation of the widespread presence of NPs. By identifying current key challenges, this Review provides valuable insights for future direction in environmental management and public health protection.

Aquatic insects as mediator for microplastics pollution in a river ecosystem of Bangladesh

Microplastics (MPs) are emerging pollutants that threaten the aquatic ecosystem. Aquatic insects may play a crucial role in moving MPs into different trophic levels within and across the ecosystems. However, field-level evidence is still insufficient globally despite its tremendous ecological significance. Thus, for the first time in Bangladesh, MPs were explored in six species of aquatic insects along with water and sediment of the Daleshwari River. Digestion and density separation methods were used for the extraction of MPs. Microscopic inspection and Fourier transform spectroscopy (FT-IR) were done to identify and quantify MPs. The average concentration of MPs in sediment and water is 143.1 ± 28.52 of MPs/L and 30153.8 ± 2313.62 of MPs/kg, respectively. In aquatic species, the highest MPs found in D. rusticus (57.82 ± 14.98 MPs/g), followed by B. contaminate (38.53 ± 6.87 MPs/g), Ranatra sp. (34.05 ± 5.39 MPs/g), C. servilia (26.99 ± 7.88 MPs/g), D. annulatus (16.44 ± 6.95 MPs/g), and O. sabina (14.13 ± 4.52 MPs/g). A total of eight types of polymers have been identified. It was important to notice that the studied aquatic insects bear similar MPs (size, shape, and color) found in water and sediments from the river. It reveals the potential for the insects (accumulators of MPs) to be a driving factor for the transport of the MPs across different ecosystems. It has also been found that Aquatic insect's size, weight, feeding habitat, and host reserviour could be responsible for MPs ingestion. In addition, ecological risk assessment (Contamination Factor, Nemerrow Pollution Index, Pollution Load Index, Polymer Hazard Index) indicates different levels of risk for the pertaining river ecosystem.

Microplastics and organic contaminants: Investigation of the sorption process on different polymer types

The presence of microplastics (MPs) in aquatic environments raises major concerns due to their ability to sorb and transport Emerging Contaminants (ECs). In this work, a sorption study was carried out, using MPs of polyester (PES), polyamide (PA), polyvinyl chloride (PVC), polypropylene (PP), high-density polyethylene (HDPE) and low-density polyethylene (LDPE), in the size range of 63 to 250 μm. Five emerging contaminants (ECs) were selected for this evaluation: Ametryn (AMT), atrazine (ATZ), bisphenol A (BPA), progesterone (PGT) and pyraclostrobin (PCT). The MPs were previously characterized by different analytical techniques and presented results in good agreement with the literature. Sorption experiments presented a predominance in the interaction of the most nonpolar ECs (PCT and PGT), with all six polymers. In general, under the evaluated conditions, the highest sorption percentages were obtained for: PA > PP > LDPE > PVC > HDPE > PES, for 24 h of contact time, that could be considered as the apparent equilibrium time, and the increase in the mass of MPs contributed for the enhancement in the sorption process, probably due to the greater availability of interaction sites. Also, the variation in ionic strength and pH caused no significant effect between the sorption of most ECs and the MPs. The results indicate a greater interaction between MPs and nonpolar contaminants, revealing that MPs play a limited role in the transport of more polar compounds in the aquatic medium.

Fate, source, and ecological risk of microplastic in the surface sediment of the Beibu Gulf, the Northern South China sea

A large-scale investigation of the surface sediments in the Beibu Gulf was conducted in this study to reveal the contamination characteristics of microplastics in the surface sediments of the Beibu Gulf. The results showed that the abundance of microplastics ranged from 12.91 to 251.69 items/kg, dry weigh (DW), with an average abundance of 84.34 ± 51.85 items/kg (DW). The highest abundance of microplastics was found in the estuary of northwestern Hainan, influenced by the West Guangdong Coastal Current. The overall distribution of abundance showed a decreasing trend from nearshore to offshore. Microplastics in the surface sediments were predominantly in the form of fiber (87.51%), with a predominant white color. The polymer of microplastics in surface sediment was primarily polyester (43.43%). The main sources of microplastics include household items, textile products, food packaging, fishing activities, industrial activities, sewage discharges, and biochemical materials, of which household products and textile products are the most important sources. The results of the risk evaluation showed that the sediment of Beibu Gulf was contaminated with microplastics (pollution load index >1) and the polymer risk was at low to extremely high levels. The high abundance of microplastics and highly toxic polymers resulted in increased ecological risk. These findings highlight the urgent need to implement timely and effective measures to reduce the impact of intensive human activities on microplastic pollution. At the same time, the study data provide an important reference for future ecotoxicological investigations, pollution management strategies and microplastic policy development.

Distribution and risks of microplastics and phthalate esters in the transition from inland river systems to estuarine and nearshore regions of the Yellow Sea, China

Microplastics (MPs) and phthalate esters (PAEs) are emerging pollutants of significant environmental and health concern. The Yellow Sea, a semi-enclosed marginal sea with dense coastal populations and industrial activities, serves as a critical region for studying MP and PAE pollution due to its ecological sensitivity, role in pollutant transport, and relevance to global marine pollution challenges. The distribution and characteristics of MPs and PAEs in surface water and sediment transitioning from an inland river system to estuarine and nearshore regions of the Yellow Sea in China were investigated. MP concentrations in water samples ranged from 0.89 ± 0.15 to 11.47 ± 1.80 items/L and in sediments from 93.33 ± 23.09 to 653.33 ± 50.33 items/kg dw. The main colors of MPs found in water and sediment samples were white and transparent, with fibers being the predominant shape. The primary size range was 0-0.5 mm, and the main polymer components were rayon and polyethylene. The characteristics of MPs in clams were similar to those in water and sediment, except that their predominant colors were black and blue. The total of six PAEs (Σ6 PAEs) was detected at concentrations between 0.30 and 1.29 μg/L in water and 25.75-163.61 ng/g in sediments. The concentrations of both pollutants demonstrated a distinct spatial gradient, with the highest levels observed in upstream urban areas, followed by progressively decreasing levels in downstream rural zones, and reaching their minimum concentrations in nearshore regions. Variations in the morphological characteristics (color, shape, and size) and polymer composition of MPs were observed between the aquatic phase and sediment phase along the direction of water flow. A significant correlation was found between MP abundance and Σ6 PAEs across both matrices. Ecological risk assessments revealed substantial risks associated with the presence of these pollutants, particularly in urban areas where contamination peaked. Clams collected from the nearshore regions exhibited MP counts of 1.91 ± 0.47 to 2.49 ± 0.63 items/individual and PAEs from 0.51 to 0.91 μg/g, posing high polymer risk from MPs yet no significant health risk from PAEs for human consumers. This study underscores the transition of MP and PAE pollution from riverine to marine environments, providing valuable insights into the critical sources and potential risks associated with marine MPs and PAEs.

Sensitivity analysis of a one-dimensional microplastic transport model in turbulent rivers: Intrinsic properties and hydrodynamics

Since rivers are major transport routes for microplastics, developing novel modeling approaches has become a subject of research to better understand the transport behavior of these particles in river systems. This study aims to model the vertical transport of microplastics at selected sites of the Ergene River, Türkiye, simulate the concentration dynamics of these particles in water and sediment under different hydrodynamic and morphological conditions, and determine the sensitivity of the model results to parameters related to the physical characteristics of microplastics, as well as river hydrodynamics and morphology. A mechanistic model was developed using data on microplastics, river hydrodynamics and morphology. Mass-balance and hydrodynamic equations were utilized for model construction in GoldSim to predict the transport of microplastics between the water column and sediment. The model results revealed that the residence time of microplastics in water was directly related to flow characteristics and river hydraulics, while the initial concentration of particles in water dominated other parameters in influencing the settling and resuspension fluxes of microplastics. Turbulent conditions affected both flow rate and particle resuspension, suggesting that turbulence can either increase or decrease microplastic concentrations and their residence time in the water column and sediment. The model results for both compartments were most sensitive to changes in water and plastic density, whereas Nikuradse sand roughness was the least significant parameter affecting the model outcomes for both compartments.

Investigation of potential toxic effects of nano- and microplastics on human endometrial stromal cells

Nanoplastics (NPs) and microplastics (MPs) have become a global concern in recent years. Most current research on the impact of plastics on obstetrics has focused on their accumulation in specific tissues in animal models and the disease-causing potential of MPs. However, there is a relative lack of research on the cellular changes caused by the accumulation of MPs. In this study, we aimed to establish a proper in vitro exposure protocol for polystyrene (PS)-NPs and MPs and to investigate possible cytotoxic effects of PS-NPs and MPs on human endometrial stromal cells (ESCs) using different plastic sizes and concentrations. The results showed that smaller plastics, specifically 100 nm PS-NPs and 1 μm PS-MPs, had a higher cellular uptake propensity than larger particles, such as 5 μm PS-MPs, with significant morphological changes and cell death observed at concentrations above 100 μg/mL a 24-h period. In addition, confocal microscopy and real-time imaging confirmed the accumulation of these particles in the nucleus and cytoplasm, with internalization rates correlating with particle size. Also, 100 nm PS-NPs reduced cell proliferation and induced apoptosis. In conclusion, this study demonstrates that exposure to 100 nm PS-NPs and 1 μm PS-MPs leads to dynamic accumulation in ESCs, resulting in cell death or decreased proliferation at specific concentrations, which highlights the potential cellular toxicity of NPs or MPs.

Microcontaminants and microplastics in water from the textile sector: a review and a database of physicochemical properties, use in the textile process, and ecotoxicity data for detected chemicals

Microcontaminants (MCs) and microplastics (MPs) originating from the textile sector are today receiving a great deal of attention due to potential environmental concerns. Environmental pressures and impacts related to the textile system include not only the use of resources (e.g., water) but also the release of a wide variety of pollutants. This review's main objective is to highlight the presence of textile MCs and MPs in water, in their full path from textile factories (from raw materials to the final product) to wastewater treatment plants (WWTPs), and finally to the receiving surface waters. Their environmental fate and ecotoxicity were also addressed. Overall, more than 500 compounds were found, many of which are so called "contaminants of environmental concern" such as per- and polyfluoroalkyl substances (PFAS) and alkylphenol compounds. A database of physicochemical properties, ecotoxicity, and place of detection (specific textile process, WWTP, surface water or sediment) (classification by several international agencies) was compiled for the chemical detected. Preliminary risk assessment was conducted for those MCs for which the reported environmental concentrations exceeded the Predicted No Effect Concentration (PNEC). These chemicals were some nonylphenols, nonylphenol ethoxylates and organophosphate esters. Among MPs, polyester and nylon fibres were the most abundant. The highest concentration of MPs was reported in sludge (about 1.4 × 106 MPs per kg) compared to wastewater and surface water which showed MP concentrations at least two orders of magnitude lower. The role of transboundary contamination due to the release of chemicals from imported textile products was also assessed.

Microplastic characterization and factors influencing its abundance in coastal wetlands: insights from the world's largest mangrove ecosystem, Sundarbans

Water and sediment samples were collected from 20 sampling sites within two major river systems within the world's largest mangrove ecosystem. The primary objectives of the study were to determine MPs' abundance, composition, and potential ecological risks and to identify the factors influencing their distribution and characteristics. Results revealed MP abundances, ranging from 2 to 53 items/m3 in water and 17 to 177 items/kg in sediment. The most prevalent types of MPs were films, fragments, foams, and fibers, with the most abundant fragments. Transparent MPs of various colors, such as red, green, blue, white, and yellow, were commonly observed. Additionally, sizes of MPs ranged from < 0.5 to 5 mm, with particles < 0.5 mm dominating in water and 4-5 mm particles prevailing in sediment. Six major polymers were identified, including polystyrene (PS), polyamide (PA), Polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), and ethylene propylene diene monomer (EPDM), with PS being the most abundant in both river systems. Linear mixed effect models showed that factors, such as distance from Mongla port and water velocity impacted MP abundance in water, while distance from Mongla port, total organic carbon (TOC), and total phosphorus (TP) contents affected their distribution in sediment. The Shannon-Weaver Index revealed a higher MP diversity in the Shela River compared to the Pasur. Overall, the pollution load index (PLI) and polymeric hazard index (PHI) indicated that MPs impacted both river systems, but the finding from the ecological risk index (ERI) was negligible at the individual sites. Our study recommends the long-term monitoring of MP abundance and implementation of strict regulations to reduce MPs in aquatic environments and proposes various engineering and biotechnological approaches for effective MP remediation. Further research is needed to identify both point and non-point sources of MPs and develop comprehensive strategies and policies to mitigate plastic pollution in the mangrove ecosystem.

Investigation of microplastic pollution index in the urban surface water: A case study in west Godavari district, Andhra Pradesh, India

Microplastics (MPs) are a growing environmental issue because of their widespread prevalence and their long-term effects on ecosystems and human health. Global studies have identified MPs in various aquatic environments, such as lake, rivers, estuaries, wastewater, and oceans. Although most MPs originate from urban surface water sources, the specific intensity, characteristics, and associated risk assessments remain unclear. This study focuses on west Godavari region of India, specifically analyzing MPs in surface water samples Godavari River and two water treatment plants (WTPs). A total of 330 MPs found in the surface water and 121 MPs in theWTP. In surface water, MPs were predominantly blue and transparent fibers, with the majority measuring less than 500 μm in size. Conversely, at the WTP, larger MPs, primarily in blue fiber form and exceeding 3000 μm, were observed. Additionally, μ-Raman spectroscopy analysis identified the presence of various polymers, including PP, PVC, PC, Nylon, and PET, among others. The risks associated with MPs, including their concentration and chemical composition, were assessed across all sample types using various indices such as Contamination Factor (CFi), Pollution Load Index (PLI), Polymer Risk Index (H), Potential Ecological Risk Index (RI), and Estimated Intake (EI) (daily, annually, and lifetime). The risk assessment revealed that the type of polymer poses a greater risk of MP pollution than the concentrations of MPs themselves. These findings provide critical insights into MP contamination patterns and risks, emphasizing the need for targeted mitigation strategies in this region.

Unravelling land-based discharge of microplastics in River Basantar of Jammu & Kashmir, India: Understanding sinking behaviors and risk assessments

Microplastics (MPs) are ubiquitous and are increasing globally, but there is limited information available on their presence in freshwater ecosystems. This research work aims to investigate the abundance, sinking behavior, and risk assessment of MPs in the freshwater River Basantar, Jammu & Kashmir, India. Microplastic abundance in sediments was recorded in the range of 1-6 items g-1, with a mean abundance of 3 ± 1.594 item g-1, whereas MPs in surface water ranged from 200 to 850 items L-1 with a mean abundance of 530 ± 218.4 items L-1 among 12 sites for sediments and 10 sites for surface water. Besides, the sinking behavior of MPs was analyzed through portioning coefficients (Kd) at sediments-surface water interface, which ranges from 0.71 to 2.50 L Kg-1 for River Basantar. The most common shapes identified were fragments, fibres, and films, followed by pellets, foams, and lines. ATR-FTIR polymeric characterization reported polyethylene, polypropylene, polystyrene, polyethylene terephthalate, and polyvinyl chloride, and thus, polymeric risk assessment analysis was also evaluated and normally distributed in the River Basantar. Polymer Hazard Index was calculated across all the sites which observed to be polluted under risk categories "III" and "IV" for both the sediments and surface water samples. Pollution Load Index (PLI) calculated across all the sites was >1 depicting all the sites for both sediments and surface water sampling to be polluted. Pollution Risk Index was assessed and majority of surface water and sediment samples were observed to be under "Very high" risk category. The study, using principal component analysis and heatmap analysis, found that MPs are primarily a result of urbanization and anthropogenic actions, like industrial discharges, household wastes, and agricultural runoffs. This study highlights the significance of more investigation and coordinated efforts to solve the worldwide problem of plastic pollution in freshwater environments. Results data provide insight into the current state of MP contamination and will help government authorities implement strict rules and perform management interventions to reduce and monitor pollution levels in River Basantar. Future studies on the partitioning of MPs in sediments and surface water must be focused on aggregation, biofouling, plastic density & size, salinity, and flow behaviors to understand transport and deposition in rivers.

Microplastic contamination and environmental risks in the Beas River, western Himalayas

The Western Himalayan mountains, with several riverine systems, are considered one of the most fragile environments in the world. Among them is Beas, a primary river that provides essential ecosystem benefits to thousands of indigenous people in North India. One of the major pollutants, microplastics (MPs), are ubiquitous contaminants, yet their occurrence in the Beas and ecological risk factors remain largely unexplored. Due to extensive tourism and urban-related burdens, the usage and release of enormous amounts of plastics and MPs into the Beas are apparent. Here, we investigated the extent of MPs pollution and subsequent environmental risks in water and sediments from Beas along a stretch of 300 km. Our results showed that MPs were abundant and widely distributed, with the abundance range (mean ± SE) being 46-222 (112.27 ± 12.43) items/L in water and 36-896 (319.47 ± 49.25) items/kg in sediment samples. We found significant differences in MPs' abundance in water but not sediments among the five sampling sites. There was a significant positive correlation between population size and the abundance of MPs, with the highest abundance in populated Kullu and the lowest loads at the remote Dhundi Glacier. Fibers and film were common morphotypes; most items measured <1 mm. Of the eleven polymers identified, the majority were polyethylene. The pollution load index ranged up to 4.99 (low-risk category); however, the polymer hazard index exceeded 1000 (highest-risk category), and the potential ecological risk index was 13,761 (extreme-risk category) at selected sites. This study fills a crucial knowledge gap and raises concerns about the possible impact on human health, as many riparian residents depend on Beas as their primary source of potable water. Our findings may assist governmental agencies in formulating comprehensive eco-friendly policies and advancing environmentally sustainable strategies in vulnerable locales adjoining the Beas waterway.

Emission characteristics analysis on microplastics by inorganic sludge discharged from recycling processes of agricultural waste vinyl in Korea

Globally, various policies are being implemented to phase out plastic, and South Korea has set targets to reduce waste and increase recycling rates by 2030. Concerns about managing microplastic pollution are growing. Most advanced research has primarily focused on aquatic ecosystems. This has left a gap in data on residues in sludge generated from agricultural waste recycling processes. Therefore, environmental analysis (leaching tests, heavy metal and microplastics content, etc.) was carried out using the inorganic sludge discharged from the agricultural waste recycling process to establish national data for various environmental analyses in this study. Specifically, inorganic sludge was selected as a sample from the agricultural waste recycling process since it would be recycled as a filling or covering material in agricultural soil. Therefore, this study analyzed and assessed the content of harmful substances and microplastics in the inorganic sludge generated from agricultural waste recycling processes. As a result, it was revealed the detection of unregulated items such as Al (leaching: 1.54 mg/L, content: 23,870 mg/kg), Fe (leaching: 0.48 mg/L, content: 27,453 mg/kg), and Mn (leaching: 0.06 mg/L, content: 649 mg/kg). Among regulated items, Cu (35.96 mg/kg), Ni (8.77 mg/kg), Pb (6.47 mg/kg), and Zn (178.39 mg/kg) were detected within the legal concentration limits. As for microplastics, the number (1814 particles) and mass (446.54 μg/g) were detected. However, the impact of microplastics is not identified clearly yet. Therefore, if the study results and subsequent accumulation of data by expanding the research target waste can be utilized, it is expected that this could serve as fundamental data for establishing policies or legislation for microplastic management systems.

Assessing microplastic pollution in a river basin: A multidisciplinary study on circularity, sustainability, and socio-economic impacts

Plastic pollution has emerged as a significant environmental challenge worldwide, posing serious threats to ecosystems and human health. This study seeks to explore the interplay among circularity, sustainability, and the release of microplastics within the freshwater ecosystems situated along the western Black Sea coast- Düzce, Türkiye. Employing a multidisciplinary approach that integrates environmental science, economics, and policy analysis, the research examines the current state of plastic pollution in the region, considering diverse land uses and socio-economic lifestyles. Conducted over four different seasons, the current study identifies the prevailing types of microplastics in the region. Fibers dominate, comprising 86.7% in each season, followed by film and fragments at 7.7% and 7.0%, respectively. Notably, polyethylene (PE) and polypropylene (PP) emerges as the primary polymer types. The distribution of polymer types varies across different land uses within the region, emphasizing the influential role of land use in shaping the abundance polymer composition. The comprehensive assessment of pollution, as reflected in the overall pollution load index (PLI) of the Melen River indicating a concerning level of pollution (PLI>1). Finally, the study unveiled the relationship between socio-economic activities as well as the seasonal precipitation patterns, and microplastic contamination in the region. This underscored the importance of site-specific mitigation measures on reducing the amount of microplastics. Lastly, incorporating sustainable practices within the circular economy framework fosters a harmonious balance between economic development and environmental protection in Türkiye.

Dynamics of plastic debris and its density change between river compartments in the Tuul River system, Mongolia

Plastic pollution in river environments has become an emerging global concern. However, the migration of plastic and changes in its properties between river compartments are less understood. This study demonstrates the plastic debris aging and the dynamics between floodplain, surface water, and sediment compartments of the Tuul River, Mongolia. Plastic occurrence is evaluated in terms of their abundance, size, shape, polymer type, and photodegradation in each compartment. Photodegradation stages were calculated using the carbonyl index (CI). Plastic abundance was 5.46 ± 3.53 items m-2 in the floodplain, 155 ± 100.7 items m-3 in the surface water, and 128.4 ± 76.3 items kg-1 in the sediment. Microplastics dominated in the size category in all compartments, while macro- and megaplastics were found only in the floodplain. Polyethylene and polypropylene dominated the surface water and sediment, while polystyrene was the predominant plastic in the floodplain. A positive correlation was found between the distributed polymer types in the surface water and sediment compartments. The similar composition in size and polymer type suggests vertical plastic migration from water to sediment. Although CI values showed that the plastic aging was significantly different between water and sediment (water, 0.61 ± 0.26, and sediment, 0.90 ± 0.68), the dominance of low-density plastics with high CI in the sediment suggests that the aged plastic density changed during the vertical transport in the river system.

Microplastics in ecosystems: Critical review of occurrence, distribution, toxicity, fate, transport, and advances in experimental and computational studies in surface and subsurface water

Microplastics (MPs), particles under 5 mm, pervade water, soil, sediment, and air due to increased plastic production and improper disposal, posing global environmental and health risks. Examining their distribution, quantities, fate, and transport is crucial for effective management. Several studies have explored MPs' sources, distribution, transport, and biological impacts, primarily focusing on the marine environment. However, there is a need for a comprehensive review of all environmental systems together for enhanced pollution control. This review critically examines the occurrence, distribution, fate, and transport of MPs in the following environments: freshwater, marine, and terrestrial ecosystems. The concentration of MPs is highly variable in the environment, ranging from negligible to significant amounts (0.003-519.223 items/liter in water and 0-18,000 items/kg dry weight sediment, respectively). Predominantly, these MPs manifest as fibers and fragments, with primary polymer types including polypropylene, polystyrene, polyethylene, and polyethylene terephthalate. A complex interplay of natural and anthropogenic actions, including wastewater treatment plant discharges, precipitation, stormwater runoff, inadequate plastic waste management, and biosolid applications, influences MPs' presence and distribution. Our critical synthesis of existing literature underscores the significance of factors such as wind, water flow rates, settling velocities, wave characteristics, plastic morphology, density, and size in determining MPs' transport dynamics in surface and subsurface waters. Furthermore, this review identifies research gaps, both in experimental and simulation, and outlines pivotal avenues for future exploration in the realm of MPs.

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.

A comprehensive risk assessment of microplastics in soil, water, and atmosphere: Implications for human health and environmental safety

Microplastics (MPs) are pervasive across ecosystems, likely posing significant environmental and health risks based on more and more evidence. In this study, we searched through the Web of Science Core Collection and obtained 1039 papers for visualization and analysis. In order to discuss the chemical composition, migration, transformation and potential risk of MPs, 135 sets of relevant data in soil, water, and atmosphere were collected in China as a typical region, which is a hotspot region for investigation of MPs. The results showed that the primary polymer categories of MPs in the environment to be polypropylene, polyethylene, and polystyrene. The soil contains a significant quantity of MPs, averaging at 12,107.42 items·kgdw-1, while water contains averaging at 97,271.18 items m-3. The total pollution load indexes for all three environments are at risk level I. Based on current risk assessment methods, the potential ecological risk of MPs is low. However, based on the polymer components, migration and transformation patterns, and especially the complexes with other pollutants, it indicates an increasing indirect risk. Interactions with some other pollutants are likely amplify the ecological and health risks associated with MPs. Aggregative results showed that the present risk assessment models could not assess the risks of MPs well. Thus, we suggested develop a risk assessment methodology for MPs based on relevant research progress. Some factors such as the size and form of MPs, sources and distribution, bioaccumulation, social acceptance and economic costs could be considered adding in the present risk assessment models. Finally, promotion of development and application of green chemically synthesized bioplastics such as using synthetic biology to help degrade plastics would be an alternative and sustainable option to relieve the adverse environmental and health concerns of MPs.

Microplastic accumulation in a lizard species: Observations from the terrestrial environments

Microplastics are a global environmental problem, polluting both aquatic and terrestrial environments. Terrestrial lizards are suitable model organisms to study human-induced pollution in these areas, as they can live in urbanized areas where microplastics are most abundant. Therefore, we analyzed the prevalence of microplastics (MPs) in a common Lacertid lizard, the snake-eyed lizard, Ophisops elegans. We detected MPs in the gastrointestinal tract (GIT) of 33 of 152 specimens from 18 populations. The detected MPs had six distinct polymer compositions, namely Polyethylene terephthalate, Polyacrylonitrile, Polypropylene, Polyethylene, Poly methyl methacrylate and Polyamide. The majority of these MPs were fiber-type and the dominant color was navy blue. The lengths of MPs varied from 37 to 563 μm, with an average length of 175 μm. MPs were detected in the GITs of 43% of juveniles (n = 7), 30% of males (n = 105), and 18% of females (n = 40), with a mean of 0.27 per specimen. Furthermore, we found that microplastic densities varied with habitat distance from human settlements, supporting the theory that high levels of microplastic contamination are associated with extensive anthropogenic activity.

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.

Investigation of microplastics and potentially toxic elements (PTEs) in sediments of two rivers in Southwestern Nigeria

Microplastics (MPs) are emerging and ubiquitous contaminants, known to accumulate in river sediments. In many developing nations, the absence of policies for managing plastic waste puts the inland river ecosystems at risk of excessive abundance of plastics and MPs. However, only limited studies have reported MPs in river environments in these countries. The current study therefore examined the abundance and nature of MPs and potentially toxic elements (PTEs) in the sediments of the Odo-Ona and Ogun Rivers in Southwest Nigeria. MPs were extracted from the sediments using the density separation method and categorized according to their size, colour and shapes. The range of MP abundances found in the Ogun River sediments was 66.6 ± 12.2 to 311 ± 20.8 particles/kg, while that of the Odo-Ona River ranged from 133 ± 50 to 433 ± 100 particles/kg. The MPs polymer analyses revealed the presence of polyethylene (PE), polypropylene (PP) and polyamide (PA) particles in the sediments. PE was most abundant in the two rivers, constituting 72.8% and 59.7% of MPs (with 0.5 - 5 mm size), recovered from the Odo-Ona and Ogun Rivers, respectively. High concentrations of Cr and Pb with ranges of 10.3 - 48.3 and 10.1 - 211 mg/kg, respectively, were detected in the sediments and were associated with anthropogenic effects. This study reveals the impact of indiscriminate waste dumping on the water bodies, and calls for strict enforcement of environmental laws in the country.

Characterization and ecological risk assessment of microplastics accumulated in sea water, sand, sediment, shell water and selected tissues of hermit crab of Sundarban Biosphere Reserve

Sundarban, a Ramsar site of India, has been encountering an ecological threat due to the presence of microplastic (MP) wastes generated from different anthropogenic sources. Clibanarius longitarsus, an intertidal hermit crab of Sundarban Biosphere Reserve, resides within the abandoned shell of a gastropod mollusc, Telescopium telescopium. We characterized and estimated the MP in the gills and gut of hermit crab, as well as in the water present in its occupied gastropod shell. The average microplastic abundance in sea water, sand and sediment were 0.175 ± 0.145 MP L-1, 42 ± 15.03 MP kg-1 and 67.63 ± 24.13 MP kg-1 respectively. The average microplastic load in hermit crab was 1.94 ± 0.59 MP crab-1, with 33.89 % and 66.11 % in gills and gut respectively. Gastropod shell water exhibited accumulation of 1.69 ± 1.43 MP L-1. Transparent and fibrous microplastics were documented as the dominant polymers of water, sand and sediment. Shell water exhibited the prevalence of green microplastics followed by transparent ones. Microscopic examination revealed microplastics with 100-300 μm size categories were dominant across all abiotic compartments. ATR-FTIR and Raman spectroscopy confirmed polyethylene and polypropylene as the prevalent polymers among the five identified polymers of biotic and abiotic components. The target group index indicated green and black as the preferable microplastics of crab. The ecological risk analysis indicated a considerable level of environmental pollution risk in Sundarban and its inhabiting organisms. This important information base may facilitate in developing a strategy of mitigation to limit the MP induced ecological risk at Sundarban Biosphere Reserve.

Hotspots lurking underwater: Insights into the contamination characteristics, environmental fates and impacts on biogeochemical cycling of microplastics in freshwater sediments

The widespread presence of microplastics (MPs) in aquatic environments has become a significant concern, with freshwater sediments acting as terminal sinks, rapidly picking up these emerging anthropogenic particles. However, the accumulation, transport, degradation and biochemical impacts of MPs in freshwater sediments remain unresolved issues compared to other environmental compartments. Therefore, this paper systematically revealed the spatial distribution and characterization information of MPs in freshwater (rivers, lakes, and estuaries) sediments, in which small-size (<1 mm), fibers, transparent, polyethylene (PE), and polypropylene (PP) predominate, and the average abundance of MPs in river sediments displayed significant heterogeneity compared to other matrices. Next, the transport kinetics and drivers of MPs in sediments are summarized, MPs transport is controlled by the particle diversity and surrounding environmental variability, leading to different migration behaviors and transport efficiencies. Also emphasized the spatio-temporal evolution of MPs degradation processes and biodegradation mechanisms in sediments, different microorganisms can depolymerize high molecular weight polymers into low molecular weight biodegradation by-products via secreting hydrolytic enzymes or redox enzymes. Finally, discussed the ecological impacts of MPs on microbial-nutrient coupling in sediments, MPs can interfere with the ecological balance of microbially mediated nutrient cycling by altering community networks and structures, enzyme activities, and nutrient-related functional gene expressions. This work aims to elucidate the plasticity characteristics, fate processes, and potential ecological impact mechanisms of MPs in freshwater sediments, facilitating a better understanding of environmental risks of MPs in freshwater sediments.

Characterization and spatial distribution of microplastics in Surma river, Bangladesh: Assessing water and sediment dynamics

Microplastics (MPs), or tiny pieces of plastic, have become a major global environmental problem because of their ubiquitous availability and possible risks to aquatic ecosystems. Surma is one of the vital rivers in Bangladesh located in the northeast part, with higher chances of MP pollution due to different anthropogenic reasons. In this instance, we carried out the investigation on the abundance, distribution, and characteristics of MPs in the sediment and surface water of the river. Samples were collected from 15 major locations of the Surma river flowing through Sylhet municipality. MPs particles were isolated from sediments and water samples utilizing techniques like sieve analysis, wet peroxide oxidation, density separation, and filtration and then characterized using a stereomicroscope. The abundance of MPs recorded 8 to 18 items/L in water samples (mean ± SD: 12.33 ± 2.98 items/L) and 360 to 1120 items/kg in sediment samples (mean ± SD: 522.67 ± 197.84 items/kg). The prominent size, shape, and color of MPs isolated from sediments were 1-2 mm sizes (24.49%), fragments (47.71%), and black (30.65%). However, for water samples, 1-2 mm sizes (37.22%), fiber shapes (48.48%), and transparent colors (38.46%) were dominant features. Conspicuously, in both sediment and water samples, there was a higher prevalence of smaller sized particles, posing a significant threat to the ecosystem. This heightened risk stems from the increased likelihood of ingestion by microorganisms, as well as the larger surface area of these particles, which may serve as vectors for other pollutants like organic pollutants and heavy metals. A greater abundance of fibers suggests an increased presence of lightweight particles in the water and sediment. Furthermore, the transparent color of the MPs in water might be impacted by prolonged weathering in the river, while the presence of black-colored MPs in sediment points to the existence of plastic pellets originating from industrial and diverse sources. Future studies should concentrate on long-term and broad monitoring, ecological effects, and practical mitigation techniques for MPs, providing essential baseline data to guide the formulation of policies in developing nations. PRACTITIONER POINTS: 12.33 items/L in surface water and 522.67 items/kg in sediment were observed. High correlation indicates a single MP source in mainstream water, differing from sediment. Fiber shapes, black, and transparent colored MPs are dominant. Higher prevalence of smaller sized MPs, posing a significant threat to the aquatic ecosystem.

Microplastics in multi-environmental compartments: Research advances, media, and global management scenarios

During the past decades, microplastics (MPs) have become an emerging concern due to their persistence and potential environmental threat. MP pollution has become so drastic that it has been found in the human food chain, breast milk, polar regions, and even the Himalayan basin, lake, etc. Inflammation, pulmonary hypertension, vascular occlusions, increased coagulability and blood cell cytotoxicity, disruption of immune function, neurotoxicity, and neurodegenerative diseases can all be brought on by severe microplastic exposure. Although many MPs studies have been performed on single environmental compartments, MPs in multi-environmental compartments have yet to be explored fully. This review aims to summarize the muti-environmental media, detection tools, and global management scenarios of MPs. The study revealed that MPs could significantly alter C flow through the soil-plant system, the structure and metabolic status of the microbial community, soil pH value, biomass of plant shoots and roots, chlorophyll, leaf C and N contents, and root N contents. This review reveals that MPs may negatively affect many C-dependent soil functions. Different methods have been developed to detect the MPs from these various environmental sources, including microscopic observation, density separation, Raman, and FT-IR analysis. Several articles have focused on MPs in individual environmental sources with a developed evaluation technique. This review revealed the extensive impacts of MPs on soil-plant systems, microbial communities, and soil functions, especially on water, suggesting possible disturbances to vital ecological processes. Furthermore, the broad range of detection methods explored emphasizes the significance of reliable analytical techniques in precisely evaluating levels of MP contamination in various environmental media. This paper critically discusses MPs' sources, occurrences, and global management scenarios in all possible environmental media and ecological health impacts. Future research opportunities and required sustainable strategies have also been suggested from Bangladesh and international perspectives based on challenges faced due to MP's pollution.

Unveiling microplastics pollution in a subtropical rural recreational lake: A novel insight

While global attention has been primarily focused on the occurrence and persistence of microplastics (MP) in urban lakes, relatively little attention has been paid to the problem of MP pollution in rural recreational lakes. This pioneering study aims to shed light on MP size, composition, abundance, spatial distribution, and contributing factors in a rural recreational lake, 'Nikli Lake' in Kishoreganj, Bangladesh. Using density separation, MPs were extracted from 30 water and 30 sediment samples taken from ten different locations in the lake. Subsequent characterization was carried out using a combination of techniques, including a stereomicroscope, Fourier transform infrared spectroscopy (FTIR) and field emission scanning electron microscopy (FE-SEM). The results showed a significant prevalence of MPs in all samples, with an average amount of 109.667 ± 10.892 pieces/kg3 (dw) in the sediment and 98.167 ± 12.849 pieces/m3 in the water. Small MPs (<0.5 mm), fragments and transparent colored particles formed the majority, accounting for 80.2%, 64.5% and 55.3% in water and 78.9%, 66.4% and 64.3% in sediment, respectively. In line with global trends, polypropylene (PP) (53%) and polyethylene (PE) (43%) emerged as the predominant polymers within the MPs. MP contents in water and sediment showed positive correlations with outflow, while they correlated negatively with inflow and lake depth (p > 0.05). Local activities such as the discharge of domestic sewage, fishing waste and agricultural runoff significantly influence the distribution of polypropylene. Assessment of pollution factor, pollution risk index and pollution load index values at the sampling sites confirmed the presence of MPs, with values above 1. This study is a baseline database that provides a comprehensive understanding of MP pollution in the freshwater ecosystem of Bangladesh, particularly in a rural recreational lake. A crucial next step is to explore ecotoxicological mechanisms, legislative measures and future research challenges triggered by MP pollution.

Dynamics of microplastic abundance under tidal fluctuation in Musi estuary, Indonesia

Tidal dynamics contribute to fluctuations in microplastic abundance (MPs). This is the first study to characterize MPs under the influence of tidal fluctuations in the Musi River Estuary. MPs samples were collected during flood and ebb tides at 10 research stations representing the inner, middle and outer parts of the Musi River Estuary. MPs were extracted to identify the shape, color and size. MP abundances were 467.67 ± 127.84 particles/m3 during flood tide and 723.67 ± 112.05 particles/m3 during ebb tide. The concentration of MPs in the outer zone of the estuary (ocean) was detected to be higher than in the inner zone of the estuary (river). The MPs found were dominated by black color, film shape and size 101-250 μm. A greater abundance of MPs at ebb tide than at flood tide implies that the Musi Estuary's largest source of emissions is discharge from the river.

Microplastic prevalence and human exposure in the bottled drinking water in the west Godavari region of Andhra Pradesh, India

Microplastics (MPs) are widespread, minute plastic particles present in various aquatic environments, raising concerns about their effect on human health and ecosystems. The detrimental effects of MPs on the environment, include the contamination of ecosystems, harm to aquatic life through ingestion, potential disruption of food chains, and long-term ecological consequences. Despite numerous studies confirming the MP's presence in aquatic environments, research specifically focused on MPs in bottled drinking water (BDW) is limited. Research on MPs in drinking water is vital to assess potential health risks and develop strategies for ensuring water safety and quality. This study fills a research gap by investigating microplastics (MPs) in nine brands of BDW in the West Godavari region of Andhra Pradesh, India. The average MP concentration in BDW was found to be 2.89 ± 0.48 items/L, with fibers being the predominant shape and sizes ranging from 500 to 1000 μm. Transparent and blue were the most common colors. From ATR-FTIR analysis, the dominant polymer found was polypropylene (PP) followed by polyethylene terephthalate (PET). The human risk assessment was also calculated using the formula of Estimated daily intake (EDI) and Lifetime intake (LTI). The calculation found that the EDI of MPs for children and adults ranged from 0.041 to 0.291 MPs per kilogram per day and 0.019 to 0.133 MPs per kilogram per day, respectively. The mean LTI of MP consumption of an individual, ranged from 17,958 to 2,54,861 MPs, considering an average age of 75 years. The current findings offer valuable information for ongoing evaluations of the potential human risks linked to MP exposure.

Mechanism of circRNA_SMG6 mediating lung macrophage ECM degradation via miR-570-3p in microplastics-induced emphysema

Microplastics (MPs) are plastic particles < 5 mm in diameter, of which polystyrene microplastics (PS-MPs) are representative type. The extracellular matrix (ECM) degradation of macrophages is associated with the development of emphysema. Additionally, circular RNAs (circRNAs) have a regulatory role in epigenetic mechanisms related to lung disease. However, the mechanisms of the ECM degradation and circRNAs in MPs-induced emphysema are still unclear. In our study, Sprague-Dawley (SD) rats were treated with 0, 0.5, 1.0 and 2.0 mg/m3 100 nm PS-MPs for 90 days in an inhalation experiment. PS-MPs-exposed rats showed elevated airway resistance and pulmonary dysfunction. Lung histopathology exhibited inflammatory cell infiltration, septal thickening and alveolar dilatation. Exposure to PS-MPs was able to induce elevated levels of ECM degradation-related markers MMP9 and MMP12, as well as reduced levels of elastin in rat lung tissues. CircRNA_SMG6 is a non-coding RNA (ncRNA) with a homologous circular structure in human, rat and mouse. The expression level of circRNA_SMG6 was decreased in both rat lung tissues exposed to PS-MPs and PS-MPs-treated THP-1 cells. The luciferase reporter gene demonstrated that circRNA_SMG6 combined with miR-570-3p and co-regulated PTEN, the target gene of miR-570-3p. Moreover, overexpression of circRNA_SMG6 or inhibition of miR-570-3p attenuated PS-MPs-induced ECM degradation in THP-1 cells. Taken together, circRNA_SMG6 may have a significant function in the deterioration of emphysema caused by PS-MPs-induced macrophage ECM degradation by regulating miR-570-3p. Our findings reveal a novel mechanism of emphysema caused by PS-MPs and provide valuable information for assessing the health risks of MPs.

Emerging isolation and degradation technology of microplastics and nanoplastics in the environment

Microplastics (MPs, less than 5 mm in size) are widely distributed in surroundings in various forms and ways, and threaten ecosystems security and human health. Its environmental behavior as pollutants carrier and the after-effects exposed to MPs has been extensively exploited; whereas, current knowledge on technologies for the separation and degradation of MPs is relatively limited. It is essential to isolate MPs from surroundings and/or degrade to safe levels. This in-depth review details the origin and distribution of MPs. Provides a comprehensive summary of currently available MPs separation and degradation technologies, and discusses the mechanisms, challenges, and application prospects of these technologies. Comparison of the contribution of various separation methods to the separation of NPs and MPs. Furthermore, the latest research trends and direction in bio-degradation technology are outlooked.

Nanoplastics Affect the Bioaccumulation and Gut Toxicity of Emerging Perfluoroalkyl Acid Alternatives to Aquatic Insects (Chironomus kiinensis): Importance of Plastic Surface Charge

Persistent organic pollutants (POPs) have been widely suggested as contributors to the aquatic insect biomass decline, and their bioavailability is affected by engineered particles. However, the toxicity effects of emerging ionizable POPs mediated by differentially charged engineered nanoparticles on aquatic insects are unknown. In this study, 6:2 chlorinated polyfluoroalkyl ether sulfonate (F-53B, an emerging perfluoroalkyl acid alternative) was selected as a model emerging ionizable POP; the effect of differentially charged nanoplastics (NPs, 50 nm, 0.5 g/kg) on F-53B bioaccumulation and gut toxicity to Chironomus kiinensis were investigated through histopathology, biochemical index, and gut microbiota analysis. The results showed that when the dissolved concentration of F-53B remained constant, the presence of NPs enhanced the adverse effects on larval growth, emergence, gut oxidative stress and inflammation induced by F-53B, and the enhancement caused by positively charged NP-associated F-53B was stronger than that caused by the negatively charged one. This was mainly because positively charged NPs, due to their greater adsorption capacity and higher bioavailable fraction of associated F-53B, increased the bioaccumulation of F-53B in larvae more significantly than negatively charged NPs. In addition, positively charged NPs interact more easily with gut biomembranes and microbes with a negative charge, further increasing the probability of F-53B interacting with gut biomembranes and microbiota and thereby aggravating gut damage and key microbial dysbacteriosis related to gut health. These findings demonstrate that the surface charge of NPs can regulate the bioaccumulation and toxicity of ionizable POPs to aquatic insects.

With spatial distribution, risk evaluation of heavy metals and microplastics to emphasize the composite mechanism in hyporheic sediments of Beiluo River

This study aimed to assess the hazardous impacts of heavy metals (HMs) enrichment on the surface of microplastics (MPs) in the hyporheic zone. The present work analyzed the spatial distribution and risk evaluation of HMs (V, Cr, Mn, Co, Ni, Cu, Zn, As, Cd, and Pb) and MPs and the mechanism of HMs enrichment on MPs in the sediments. The highest rates of contamination were for Cd, Pb, and As. The main types of MPs were fiber, blue, and a size smaller than 500 µm. The lower reaches of the Beiluo River had the most serious HMs and MPs pollution, especially BL-10 (HMs: CF-Cd, 41.91; EF-Cd, 50.87; Igeo-Cd, 4.80; RI, 1291; PN, 29.83; MPs: abundance, 890 ± 18 items/kg). Meanwhile, the principal component analysis showed that natural, industrial activities, and agricultural production and transportation were primary HMs sources in sediments, and Cd, Co, and Pb were the main enriched metals on the surface of MPs. More importantly, regarding the interaction mechanism of these composite pollutants, we concluded that electrostatic adsorption and biofilm mediation were the main mechanisms of the synergistic effect. Overall, our findings provide a theoretical basis for further research on the ecotoxicity of composite pollutants in aquatic environments.

The path of microplastics through the rare biodiversity estuary region of the northern Bay of Bengal

Due to its harmful effects on ecosystems and human health, microplastic (MP) pollution has become a significant environmental problem on a global scale. Although MPs' pollution path and toxic effects on marine habitats have been examined worldwide, the studies are limited to the rare biodiversity estuary region of Hatiya Island from the northern Bay of Bengal. This study aimed to investigate the MP pollution path and its influencing factors in estuarine sediments and water in rare biodiversity Hatiya Island in the northern Bay of Bengal. Sixty water and sediment samples were collected from 10 sampling sites on the Island and analyzed for MPs. The abundance of MPs in sediment ranged from 67 to 143 pieces/kg, while the abundance in water ranged from 24.34 to 59 pieces/m3. The average concentrations of MPs in sediment and water were 110.90 ± 20.62 pieces/kg and 38.77 ± 10.09 pieces/m3, respectively. Most identified MPs from sediment samples were transparent (51%), while about 54.1% of the identified MPs from water samples were colored. The fragment was the most common form of MP in both compartments, with a value of 64.6% in sediment samples and 60.6% in water samples. In sediment and water samples, almost 74% and 80% of MP were <0.5 mm, respectively. Polypropylene (PP) was the most abundant polymer type, accounting for 51% of all identified polymers. The contamination factor, pollution load index, polymer risk score, and pollution risk score values indicated that the study area was moderately polluted with MPs. The spatial distribution patterns and hotspots of MPs echoed profound human pathways. Based on the results, sustainable management strategies and intervention measures were proposed to reduce the pollution level in the ecologically diverse area. This study provides important insights into evaluating estuary ecosystem susceptibility and mitigation policies against persistent MP issues.

A characterization and an exposure risk assessment of microplastics in settled house floor dust in Istanbul, Turkey

The presence of microplastics in the indoor environment presents growing environmental and human health risks because of their physicochemical and toxic characteristics. Therefore, we aimed to isolate, identify, and characterize plastic debris in settled house floor dusts. This study is a rare study which assess the risks of plastic debris in settled house dust through multiple approaches including the estimated daily intake, pollution loading index, and polymer hazard index. The results indicated that polyethylene and polypropylene were the predominate polymer type of plastic debris in settled house dust with various shapes and colors. The risk assessment results also indicated the serious impact of microplastics in terms of extremely dangerous contamination as well as the fact that they present a polymer hazard. Results indicated that humans have a higher risk of exposure to microplastics via ingestion rather than inhalation. In addition, infants had a higher risk of potential intake compared to other age groups.

Characteristics and seasonal variation of microplastics in the wastewater treatment plant: The case of Bursa deep sea discharge

Microplastics (MPs) are an emerging pollutant that can be detected in all ecosystems, especially aquatic ecosystems. Wastewater treatment plants (WWTPs) are important point sources of MP release into the sea. In this study, the characteristics of MPs in wastewater and sludge samples taken from different units of WWTP in Bursa-Gemlik district for 12 months were investigated. Wastewater and sludge samples collected from 7 different points were classified as size, shape, color, and counted. The amount of MP in the influent and effluent of the WWTP, respectively; 107.1 ± 40.2 MP/L and 4.1 ± 1.1 MP/L. Although the MP removal efficiency of the WWTP is 96.17 %, approximately 74,825,000 MP is discharged into the Marmara Sea every day. The amount of MP in the sludge is 14.3 ± 7.1 MP/g. The amount of MP accumulated in 22tons of waste sludge formed daily in WWTP was calculated as 314,600,000 MP, and the annual accumulated amount was calculated as approximately 1.15 × 1011 MP. The MPs in the WWTP were mainly 1-0.5 mm in size. Fibers were the dominant MP shape in both the wastewater and sludge samples. Black and transparent were the dominant MP colors. Seven different polymer types of MPs were detected, which were mainly types of polyethylene, polypropylene, and polyethylene terephthalate. Despite the high removal efficiency in the investigated WWTP, it has been shown that it acts as an important source of MPs to the sea ecosystem due to the high discharge rates.