Microplastic contamination is ubiquitous in riparian soils and strongly related to elevation, precipitation and population density

Microplastics in wastewater treatment plant: Characterization of changes, influencing factors, and their impact on the spatial distribution of pathogenic bacteria

Wastewater treatment plants (WWTPs) have been proposed as pivotal convergence points for microplastics (MPs) and hotspots of bacterial pathogens. In this study, the characteristics of MPs and bacteria in the sewage/sludge were investigated and their relationship was formulated. Meanwhile, this study innovatively focused on the impact of MPs on microbial aerosolization process in WWTP. MPs and pathogenic bacteria were identified in sewage/sludge samples from all treatment steps, in which the levels and compositions of them vary. However, Bacillus, Planifilum, Achromobacter, and Geobacillus were the dominant genera in bioaerosol samples. The dominant shape of MPs was fibers and fragments. The main size range of MPs were 0.5 - 1 mm, with the primary type of polyethylene and polypropylene. White was the most prevalent color. Furthermore, a significant correlation between MPs and bacterial community structure in sewage/sludge was observed. The abundance and some characteristics of MPs showed positive correlations with the relative abundances of some potential pathogens, including Bacillus, Pseudomonas, Staphylococcus, Acinetobacter and Achromobacter. Aeration experiments demonstrated that the presence of MPs exerted an influence on the microbial aerosolization process. Collectively, this study provides a better understanding of the relationship between MPs and bacterial structures in a WWTP and offers new insights to the role of MPs on the microbial aerosolization process. The findings will provide a basis for the control and reduction of MPs and bacterial pathogens in WWTPs.

Size over substance: Microplastic particle size drives gene expression and fitness loss in a freshwater insect

Microplastics (MP) are a diverse class of contaminants for which it is challenging to assess their effects on freshwater biota. As polyamide (PA) and polyvinyl chloride (PVC) are two of the most abundant microplastic materials in natural environments, the present study investigated whether their chronic presence, particle size (< 100 μm and > 100 μm) and their mixture influenced gene transcription patterns and inclusive fitness of C. riparius. Transcriptome data as the lowest phenotypic trait level suggested that MP exposure impacted a range of organismic processes like oxidative stress and inflammations, leading to an innate immune response, downregulation of metabolism in organs directly exposed to the particles and triggered premature molting, regardless of the MP material or their mixture. A life-cycle fitness assessment was performed using PA, PVC and a mixture of both in, respectively. The integration of the fitness components survival, developmental time and fertility into the daily population growth rate as comprehensive fitness parameter on the highest trait level showed that any chronic microplastic exposure led to a considerable fitness loss. Partitioning the effects of substance and size class showed that microplastic exposure as such and size played an important role, while the MP material was of minor importance. The observed decrease in daily population growth rates between 2.3 and 7.6 % upon chronic MP exposure suggested a dramatic reduction of the species' population size and thus for freshwater ecosystems.

Impact of land-use patterns on soil microplastics: Distribution characteristics and driving factors in southern China's Pearl River Delta

Land-use type may affect the abundance, polymer types, and distribution characteristics of soil microplastics (MPs), but their distribution remains unknown in the Pearl River Delta region of Guangdong Province. Here, the abundance of MPs in film-mulched soil, farmland, orchard and forest soils was investigated, and characteristics of the MPs (shape, size, color, and polymer composition) were analyzed in soil samples collected from 23 sites. The average abundance of MPs in film-mulched soil, farmland, orchard and forest soil in the southern China were 2981.8, 4179.2, 2393.3 and 1486.7 items kg-1 respectively. Small particles (< 1 mm), fragments and transparent particles were the main characteristics of the MPs observed. The correlation analysis showed that the total abundance of MPs was positively correlated with the precipitation, urbanization level, and soil pH, while negatively correlated with wind speed, indicating their roles in MP deposition and transport. Furthermore, the polymer composition analysis reveals the local sources of MPs and high heterogeneity. These findings emphasize the complex dynamics of MPs are shaped by meteorological factors, anthropogenic activities, and soil properties, which are significant for follow-up studies of MP pollution control and remediation.

Explorations in the dark continent: Did microplastics and microfibres get here before us?

Microplastic and microfibre pollution is a global concern, however, karst areas remain understudied. Because of their properties, these anthropogenic microparticles are particularly hazardous, and easily transportable, reaching also remote areas. The underground world, called also dark continent, is a treasure of information, and remained the last frontier of terrestrial exploration: many parts of the underground world have not yet been accessed. In the hypogeal environments, pollution is closely linked to the connections between surface and subterranean habitats, the hydrodynamics of the aquifer, geology, and local environmental conditions. This study aims to investigate, for the first time, the presence of microplastics and microfibres in unexplored caves, revealing how human activity could indirectly impact even the uncontaminated environments of the dark continent. Together with speleologists, we collected and investigated sediment samples from unexplored caves of the Abruzzo Region, Italy. Examined anthropogenic microparticles were counted and characterized by composition, size, shape, fluorescence, and colour, via microscopy and spectroscopy. Microplastic concentrations resulted low or absent, moreover, natural and regenerated microfibres ones were higher. Fibre-shape was the most common. Most of the microparticles were clear and fluorescent under UV light. Pollution sources in this area likely include atmospheric deposition, nearby human activities, roads, and garbage. These results highlight anthropogenic microparticle pollution exists in unexplored karst caves, which could impact subterranean habitats, species, and water resources. Given the link between surface and underground karst environments, more monitoring and protection are needed. This work encourages speleologists to collect samples during explorations too, as these rarely studied environments offer crucial insights into karst systems, potential threats, and conservation needs. Future long-term studies will clarify pollutant sources, transport, and effects on ecosystems.

Microplastics accumulation in leaf litter: Field evidence for microplastic ingestion and transfer through prey-predatory relationships

Microplastics (MP) contamination of the terrestrial environment is a global concern. The contamination level of MPs in leaf litter and soil fauna that feed on it has not been reported. Moreover, the interspecific relationships among field soil fauna at different trophic levels and their effects on MP loads remain unclear. Thus, we selected a model food chain including a prey-isopod and predatory-spider relationship to evaluate the role of this relationship in the MPs body burden. The results showed that MP concentrations in the fallen leaf litter ranged from 5340 ± 336.15 particles/kg to 10920 ± 432.43 particles/kg dry weight during different seasons of the monitoring year. However, we found MP particles ranged from 1.17 ± 0.25 to 10.11 ± 1.02 particles/ind in isopods and 2.25 ± 0.35 to 4.25 ± 0.35 particles/ind in spiders. All extracted MPs were colored and blue was the most prevalent one. Fiber-shaped polyester (≤500 μm) and (501-1000 μm) were the most common MPs size in tested fauna and leaf litter, respectively. Our findings indicate that MP ingestion by isopods pose a significant risk for higher trophic levels in the terrestrial food chain. Magnification of MPs was observed in the predatory spider with MP concentration increasing from 46.45 ± 16.68 particles/gm wet weight in isopod to 147.51 ± 54.4 particles/gm wet weight in spider, annually. Furthermore, the results indicate that these soil invertebrates may represent a source of MPs to other organisms in the environment.

Tracking the microplastic pollution in the freshwater environments of southeastern Türkiye: Usage of Unio delicatus, Unio Terminalis and Dreissena polymorpha as bioindicators of microplastics

Microplastic (MP) pollution levels in aquatic environments raise concerns regarding the potential harm to biota and the environment. Mussel species are categorized as perfect bioindicator of pollutants due to their sessile lifestyle, and filter-feeding activity that also make them more prone to microplastic contamination. This study was designed to assess microplastic pollution levels in the soft tissues of dominant freshwater mussel species to understand general picture in microplastic contamination of the ambient environment. For that purpose, microplastic presence in the soft tissue of Unio delicatus (n:49), Unio Terminalis (n:31) and Dreissena polymorpha (n:82) was investigated. Including all examined specimens, mean microplastic abundance was found as 0.6 ± 0.8 items/ind, 0.2 ± 0.5 items/g ww with occurrence rate of 48 %. Reflecting global distribution, general morphological characteristics of MPs were fiber shape, blue colored and less than 500 μm in size. Fourier transform infrared (FTIR) spectroscopy identified the polymer type of MPs as polyethylene (40 %), polypropylene (47 %), and polystyrene (27 %). The results obtained in this study provide baseline information regarding microplastic contamination in freshwater environments and emphasize the need of protective measures.

Microplastics in the Amur tiger's habitat: Occurrence, characteristics, and risk assessment

Microplastics (MPs) are emerging environmental pollutants that pose a significant threat to wildlife within forest ecosystems. However, the quantity and types of MPs in wildlife forest habitats remain unclear. This study is the first to assess the distribution of MPs in the Amur tiger habitat of northeast China. Our results showed that MPs were detected in soil, water, atmosphere, forage plants, and ungulate and top predator feces within the forest ecosystem, respectively. The average diameter of all detected MPs was 44.99 ± 34.80μm. The predominant polymers found in the samples were polyamide, polyvinyl chloride, and polyurethane. Certain sample types shared similar MP polymer type distributions, indicating potential links in their sources and transfer pathways. Consequently, these findings provide some new insights on the new pollution problem in Amur tiger forest habitats and prompt us to consider how to control and manage the MPs pollution sources in the tiger conservation.

Insights into effects of drying-wetting cycles on dissolved organic matter and Cd bioavailability in riparian sediments amended with microplastics

Microplastics (MPs) affect the fractionation of cadmium (Cd) by altering physicochemical properties of sediment. However, differences in the effect of drying-wetting cycles on the bioavailability of heavy metals and dissolved organic matter (DOM) in sediment amended with MPs remain unclear. In this study, we investigated the influence of polystyrene (PS), polylactic acid (PLA), and tire wear particles (TWPs) at concentrations of 0.5% and 5% (w/w) on Cd fractionation and DOM properties of sediment under drying-wetting alternation conditions. The results showed that the surface of MPs displayed obvious increase in surface roughness and oxygen-containing functional groups after drying-wetting cycles. At the end of drying-wetting cycles, 0.5% and 5% MPs significantly decreased the sediment pH. And 5% PLA MPs and TWPs significantly increased the content of dissolved organic carbon (DOC). Besides, Cd bioavailability showed a slight decrease under wet conditions. However, 5% PLA MPs significantly increased F1 fraction by 7.82%-13.50%, which may be related to the release of additives. The aromaticity and humification degree of sediment-derived DOM were improved under drying-wetting alternation conditions. Further correlation analysis indicated that MPs indirectly affected Cd fractionation by influencing the sediment DOM properties. This study provides a new perspective for understanding the influence of MPs on the relationship between DOM and heavy metals in riparian sediments under typical hydrological condition.

Extraction and characterization of microplastics in biomined good earth fractions: assessment of urban and suburban landfill sites, India

The sustainability of biomined landfill sites mainly depends on the profitable valorisation of landfill mined wastes based on the physical and chemical properties of the materials. This study focuses on the extraction, concentration, and characterization of microplastics (MPs) as an emergent pollutant in biomined good earth fractions derived from five landfill sites in West Bengal, India: Baruipur, Dhapa, Madhyamgram, Chandannagar, and Howrah. The concentration of MPs in these samples ranged from 11,500 ± 707.1 to 34,500 ± 7778.2 particles/kg having average sizes 1000-2000 µm. Morphological analysis revealed that fragments, films, and fibers are the common MP types across all samples, with sky, black, and red being the predominant colours. µFTIR analysis identified HDPE and LDPE as the primary polymers in the good earth materials derived from all landfill sites, followed by PP, Cellophane, PVC, PS, EPM, EPS, and PET. Pollution Load Index (PLI), Polymer Hazard Index (PHI) and Potential Ecological Risk Index (PERI) were used to assess the risk of good earth materials. PLI values indicated relatively low pollution load, while elevated PHI values exceeding 1000 were noted in Howrah, Dhapa, and Chandannagar due to the presence of PVC. The study suggests the need for standardized methods to extract and quantify MPs in good earth products from landfill sites and the development of protocols or guidelines for the application of good earth in sustainable development projects.

Driving factors and sources of microplastics in soils in the Yellow River source area

Microplastics (MPs) are widespread in various environments worldwide, they pose a serious threat to ecosystems. As a typical remote area, the Qinghai-Tibetan Plateau (QTP) has a sophisticated road system. However, the contributions of anthropogenic and natural factors to MP accumulation in remote plateau regions remain unclear. Here, we investigated the distribution, driving factors, and main sources of MPs in the source area of Yellow River on the QTP. MPs in soil showed an average abundance of (75.39 ± 49.16) items/kg, which was approximately 1-103 lower than that in the lower sections of Yellow River. Film, transparent color, and polyethylene were the common shapes, colors, and polymers, respectively. Under different land uses, MP abundance was remarkably higher in nonagricultural soils than in farmland. The influencing factors, source analysis on the basis of MP characteristics, and statistical analysis (redundancy analysis and structural equation modeling) showed that MP abundance was influenced by nonagricultural activities (tourism, traffic, and grazing). Utilizing the conditional fragmentation model, we further revealed that MP abundance in the upstream and downstream regions was related to roadside dust (traffic) and atmospheric dust. It was associated with human activities, including plastic packaging waste from tourism and herdsmen, in the midstream region. Moreover, MPs in farmland were related to local sources (fertilizers). These results provide valuable information on MP distribution in headstream areas and thus contribute to controlling potential MP pollution on the QTP.

Combined pollution of soil by heavy metals, microplastics, and pesticides: Mechanisms and anthropogenic drivers

Soil is the foundation of terrestrial ecosystems and a critical resource for agricultural activities. This study investigated internal mechanism and interaction of heavy metals, pesticides (atrazine, pyrimazole and chlorpyrifos) and microplastics in soil. Specifically, certain sampling points exhibited elevated levels of individual heavy metals (Cd, Cr, Zn), exceeding the screening values, while both microplastics and pesticides demonstrated high variability, increasing the potential ecological risks. The interaction between microplastics, heavy metals, and pesticides is complex, involving electrostatic adsorption, surface complexation, biofilm mediation, and physical absorption. From a broader perspective, both heavy metals and microplastics were found to exacerbate the ecological risks posed by pesticides. Further, structural equation model and geographical weighted regression were used to reveal the driving mechanism behind complex pollution, with economic development emerging as a significant factor influencing pollution levels. These findings enhance our understanding of the combined pollution of heavy metals, microplastics, and pesticides.

From pollutant to purifier: Leveraging plastic waste-derived activated carbon for sustainable water remediation solutions

The ubiquitous presence of plastic waste presents a significant environmental challenge, characterized by its persistence and detrimental impacts on ecosystems. The valorization of plastic waste through conversion into high-value carbon materials offers a promising circular economy approach. This review critically examines the potential of plastic waste-derived activated carbon (PAC) as a sustainable and effective adsorbent for water remediation. The manuscript commences with a concise overview of the multifaceted nature of plastic pollution, highlighting its classification, environmental implications, and the limitations of existing waste management frameworks. Subsequently, it delves into the intricacies of PAC production, critically analyzing various preparation methods and their associated challenges. A comprehensive exploration of modification strategies, including chemical activation and surface functionalization, is undertaken to elucidate their role in enhancing PAC's adsorption selectivity and capacity for diverse pollutants. The effectiveness of PAC in removing a diverse array of pollutants, including emerging contaminants and recalcitrant organic compounds, is thoroughly examined. While acknowledging the influence of key factors such as pollutant characteristics and solution chemistry on adsorption efficiency, the review also identifies critical challenges, including the high production costs associated with PAC synthesis, variability of plastic waste composition, the potential for leaching of residual monomers, and the complexities of multi-pollutant adsorption. Future research directions are outlined, emphasizing the need for advanced characterization techniques, computational modeling to optimize adsorbent design, and rigorous life cycle assessments to evaluate the environmental sustainability of PAC production. By addressing these challenges, PAC offers a promising pathway towards a circular economy, mitigating plastic pollution while providing a sustainable and effective solution for water remediation.

Investigating the amount of macro, meso, and microplastics in the surface soil around the landfill of Tabriz and the effect of the prevailing wind on their distribution

Environmental pollution with plastic and microplastics (MPs) is a global problem. This study investigates macro, meso, and MPs in the soil around the Tabriz landfill in northwest Iran and the effect of prevailing wind on their distribution. One control sample and one sample from the landfill itself, 20 samples in four directions at regular intervals in the direction of the prevailing wind and against it, and two perpendicular directions (22 samples) were taken and analyzed. The results showed that the landfill is poorly managed, and in fact, it is an unsanitary landfill/dump site. The soil around it is polluted with the average abundance of macro, meso, and MPs equal to 6.5 ± 10.4 item/kg(dw), 15.5 ± 28.3 item/kg(dw), and 470 ± 193 item/kg(dw) respectively. The prevailing wind in the region has had no significant effect on the dispersion and distribution of MPs. The most abundant MPs in the soil of the studied area belonged to fragment and film-shaped particles, respectively, and the most abundant color was white. Indiscriminate use of plastics, especially single-use plastics, lack of attention to the hierarchy of waste management, as well as the lack of proper management of the landfill and turning it into a waste dump, are among the most important reasons for the presence of macro, meso, and MPs in the soil of the studied landfill.

Predicting microplastic quantities in Indonesian provincial rivers using machine learning models

Microplastic pollution has surfaced as a critical environmental concern, affecting ecosystems and human health globally. This study explored the application of several machine learning models, including the Tree algorithm, k-Nearest Neighbors (kNN), Random Forest (RF), Linear Regression (LR), Support Vector Machine (SVM), and Neural Networks (NN), to predict microplastic concentrations in the rivers of Indonesia's 24 provinces. By utilizing both environmental and anthropogenic data, the Tree algorithm exhibited the best performance, achieving a coefficient of determination (R2) of 0.838 and a mean absolute percentage error (MAPE) of 0.242 on unseen testing data, thereby highlighting strong predictive capability. Key variables influencing microplastic abundance included annual average temperature, gross domestic product (GDP) per capita and population density. The results underscored the necessity of utilizing comprehensive datasets for effective modeling and highlighted the potential of machine learning to enhance environmental monitoring efforts. This research provides critical insights for policymakers and stakeholders aiming to address the growing issue of microplastic pollution in freshwater systems, providing a foundation for the development of more effective environmental management strategies.

Microplastic in bivalves of an urbanized Brazilian estuary: Human modification, population density and vegetation influence

Microplastics (MPs) global ubiquitously affects particularly coastal regions under significant anthropogenic pressures, where there are limited monitoring efforts. Bivalves are valuable sentinels of MPs contamination. This investigation determined MP contamination in oysters, clams, and mussels at Santos-São Vicente, a heavily urbanized estuary in Brazil, focusing on socio-environmental predictors, spatial distribution, and interspecies variations. Elevated MPs levels were linked to higher human modification (β = 0.5747, p = 0.0223) and reduced population density (β = -8.918e-06, p = 0.0443), regardless of vegetation cover (p > 0.05). Such a negative connection between population density and MP contamination occurred due to the significant presence of industrial and port activities, leading to high MP discharges despite a low population. The simultaneous presence of the three species at specific sites is an intrinsic limitation for broad spatial studies, depending on their environmental availability. Despite higher concentrations in clams, mussels and oysters also exhibited spatial variations in MP concentrations, serving as suitable sentinels. The central and left segments of the estuary displayed elevated MP concentrations, consistent with a well-known contamination gradient. Clams accumulated more MPs (1.97 ± 1.37 [0.00 - 5.55] particles.g-1) than mussels (0.72 ± 1.07 [0.00 - 7.74] particles.g-1) and oysters (0.70 ± 1.03 [0.00 - 7.70] particles.g-1), suggesting higher bioavailability in sediments than the water column. MPs found across all species were predominantly smaller (<1000 µm), fragments or fibers, and colorless. These discoveries lay a groundwork for prospective global investigations by linking MPs concentrations to socio-environmental predictors, contributing to the development of local mitigation measures and global discussions.

Microplastics influence nutrient content and quality of salt-affected agricultural soil under plastic mulch

Northeast China is an important food production base and plays a crucial role in national food security. However, the increase in salt-affected soils poses a challenge to agricultural production in this region. Plastic mulching is an effective technique for saline cropland improvement, and although it has increased crop yields in the short term, its long-term application may have introduced the problem of contamination by microplastics (MPs). The distribution of MPs in salt-affected cropland, along with the effects on soil nutrients, remains largely unknown. Accordingly, the presented research selected salt-affected cropland as the research object, after which MPs were quantified from 46 soil samples from currently mulched and unmulched fields. MPs abundance in the sampled soils ranging from 4.10 × 103∼1.50 × 104 particles per kilogram of dry soil. The detected MP polymers were mainly high-density polyethylene (46%), polypropylene (22%) and polyvinyl chloride (20%). The MP particles most commonly fell under the size ranges of 50∼100 μm (35%) and 100-200 μm (28%), both of which are small particle sizes. The most commonly detected MP shapes were film (34%) and fragment (31%). The mulched samples from salt-affected cropland generally showed higher soil nutrient contents than the unmulched samples. Moreover, MP abundance, type, size, and shape all demonstrated strong correlations with soil organic carbon and total nitrogen. MP type is a major factor determining soil nutrient content. Plastic mulching serves as an important source of MPs in salt-affected cropland, with these contaminants affecting nutrient content. Future research should be broader in scope and include ecological benefits and policy implications, with a view to optimizing the problem of MPs contamination due to mulching.

Factors Influencing the Vertical Migration of Microplastics up and down the Soil Profile

Soil ecosystems are under serious threat from microplastics (MPs), and this is causing worldwide concern. The relationship between soil and MPs has become a popular research topic, and the vertical migration of soil MPs is of increasing interest. This Review summarizes the current status of research into the factors affecting the vertical migration of soil MPs. Published research shows that the characteristics of MPs and the physicochemical properties of the soil affect the infiltration process. Soil organisms play a key role in the vertical migration by acting as vectors or as a result of adsorption. Dissolved organic matter and metal oxides transfer MPs by adsorption-desorption. In addition, rainfall and dry-wet cycles alter the mobility of soil MPs, leading to changes in migration processes. Agricultural activities such as tillage and irrigation may distribute MPs throughout the topsoil. Vertical migration of soil MPs is a process influenced by a combination of factors, and the role of these factors in MP deposition needs to be explored further.

Characteristics of soil microplastics and ecological risks in the Qilian Mountains region, Northeast Tibetan Plateau

Microplastics (MPs) pollution has become a vital global environmental issue. However, comprehensive understanding of the ecological risks of MPs in soils of Northeast Tibetan Plateau still requires further study. In this study, we used the Agilent 8700 Laser Direct Infrared (LDIR) spectroscopy to analyze the characteristics of 10-1000 μm MPs in soils of different vegetation types throughout the Qilian Mountains basin, and to comprehensively explore the ecological risks of MPs in various ecological environments. The results indicate that MPs abundance is highest in soil of shrub areas (26,369 ± 32,147 items kg-1-dry weight (dw)), followed by woodland (22,215 ± 22,544 items kg-1-dw), desert (17,769 ± 9,040 items kg-1-dw), grassland (16,462 ± 12,872 items kg-1-dw), and forest (15,662 ± 13,857 items kg-1-dw). MPs in soils of different vegetation types show similar physical and chemical characteristics, with the shape dominated by fragments (93%-96%), followed by fibers and a few beads, with dominant sizes of 10-30 μm (63%-76%), and polymers dominated by polyamide (PA) and polyethylene terephthalate (PET). Additionally, the environmental risks posed by the fundamental characteristics of MPs have been quantified through the Pollution Load Index (PLI), Pollution Hazard Index (PHI), and Potential Ecological Risk Index (PERI) models. According to the PLI assessment, the current levels of MPs in the environment have not yet imposed significant burdens on the ecosystem. However, the results of PHI and PERI indicate a higher risk of MPs pollution in the Qilian Mountains. This study offers vital information for MPs pollution in the whole Qilian Mountains regions and their potential environmental risks in remote areas' soil.

Characterization of microplastic contamination and influencing factors in different environmental compartments of a coal mining subsidence area in northern Anhui, China

Environmental pollution caused by microplastics (MPs) has garnered significant global attention, however, research on MPs contamination of various environmental compartments within mining regions remains limited. The objective of this study was to investigate the occurrence and distribution of MPs in soil, surface water, and sediment, as well as the factors influencing the distribution of microplastics in the Panji Mining Area in Huainan City, Anhui Province, China. The findings indicate that MPs contamination in soil and surface water within the study area is substantial. The average abundance of MPs in soil, surface water, and sediment were 1860.8 n·kg-1, 11,323.7 n·m-3, and 384.0 n·kg-1, respectively. The dominant MPs were transparent, fibrous particles <0.1 mm, with polyethylene (PE) common in soil and polypropylene (PP) prevalent in surface water and sediment. A significant correlation was observed among MPs and environmental factors such as pH, total phosphorus (TP), and total organic carbon (TOC) (p < 0.05) showed a positive correlation in soil while in sediment, MPs abundance showed a positive correlation with pH and TOC (p < 0.05). Additionally, a positive correlation was observed of MPs abundance with pH, total nitrogen (TN), and nitrate nitrogen (NO₃--N) (p < 0.05) in surface water. This study provides insights into the characteristics, distribution, and environmental risks of MPs in mining areas, laying a foundation for the development of prevention and control strategies to mitigate MPs pollution in these regions.

Occurrence and characteristics of microplastics across the watershed of the world's third-largest river

While rivers as primary conduits for land-based plastic particles transferring to their "ultimate" destination, the ocean, have garnered increasing attention, research on microplastic pollution at the scale of whole large river basins remains limited. Here we conducted a large-scale investigation of microplastic contamination in water and sediment of the world's third-largest river, the Yangtze River. We found concentrations of microplastics in water and sediment to be 5.13 items/L and 113.9 items/kg (dry weight), respectively. Moreover, microplastic pollution levels exhibited a clear decreasing trend from upstream to downstream. The detected microplastics were predominantly transparent in color, with fibrous shapes predominating, sizes mainly concentrated below 1 mm and composed primarily of PP and PE polymers. Our analysis results indicated that compared to geographical and water quality parameters, anthropogenic factors primarily determined the spatial distribution pattern of microplastics. Moreover, the microplastic abundance in sediment upstream of the dam was significantly higher than that in the downstream sediment, while the trend of microplastic concentrations in water was opposite. Therefore, more effort is needed to monitor microplastic contamination and their ecological environmental effects of sediment before dams in future research.

Ageing behavior of starch-based food packaging bioplastics in riparian sediments and sediment-derived dissolved organic matter in the soil environment

Riparian sediment (RS) is a translational zone separating aquatic and terrestrial ecosystems. To this date, the bioplastic's UV ageing and biodegradation features in these contaminated sediments remain unknown. It is a considerable concern to investigate whether a food packaging film can interact with RS and riparian sediment-derived Dissolved Organic Matter (RS-DOM) during biodegradation and UV ageing respectively, after disposal in a natural environmental setting. To address this research gap, for the first time, this study investigates the biodegradation and UV ageing of starch/PPst/GTR films intended for food packaging applications in RS and RS-DOM respectively. The findings revealed that RS comprises major fulvic acid DOM components. Remarkably, research demonstrates the leaching of humic acid-like DOM from the film promotes aromaticity and humification as UV ageing progresses from the third to the tenth day. Comparable DOM samples were darkly analysed, revealing aromatic proteins I and II. Furthermore, an elevated carbonyl carboxyl index confirmed significant degradation of films during UV ageing. Lesser humification, aromaticity, and higher biological activity were confirmed by a HI < 10 and BIX > 0.6 respectively. In comprehension, these findings reveal that the starch/PPst/GTR food packaging film will have a lesser adverse environmental impact after disposal, offering a hopeful outlook for the future of bioplastics.

The dual role of coastal mangroves: Sinks and sources of microplastics in rapidly urbanizing areas

Mangrove ecosystems are vital for coastal protection, biodiversity, and pollution interception, yet their interactions with microplastics in rapidly urbanizing regions remain underexplored. This study investigated the microplastic dynamics in the Maozhou River and Dasha River, along with the coastal Xiwan Mangrove Park in the Pearl River Estuary, the second largest estuary in China. Samples were collected from mangrove and surrounding areas, identifying microplastics using Fourier-transform infrared spectroscopy (FTIR) and Laser Direct Infrared (LDIR) techniques. Microplastic concentrations ranged from 245.8 to 1562.4 n/m³ in water and 374.3 to 7475.3 n/kg in sediments. The Maozhou River exhibited consistent microplastic levels across varying hydrological conditions, while the Dasha River and Xiwan Mangrove showed greater sensitivity to water flow changes influenced by urban land use. During high-flow periods, urban river microplastic concentrations decreased due to dilution, whereas mangrove areas experienced elevated levels in water from urban runoff, upstream retention, and sediment resuspension, suggesting a potential for outward release. Weaker water dynamics led to increased microplastic accumulation in mangrove sediments. The distribution of microplastic types was influenced by multiple urban pollution sources, with synthetic rubbers linked to urban transportation comprising over 50 % of some samples, peaking at 79 %. These findings underscore the dual role of mangroves as microplastic sinks and potential sources, highlighting the significant impact of hydrological conditions on their function. This study offers new insights into microplastic pollution in urban mangrove ecosystems and emphasizes the urgent need for improved management strategies in coastal areas facing rapid urbanization.

Microplastics and benthic animals reshape the geochemical characteristics of dissolved organic matter by inducing changes in keystone microbes in riparian sediments

Dissolved organic matter (DOM) in riparian sediments plays a vital role in regulating element cycling and pollutant behavior of river ecosystems. Microplastics (MPs) and benthic animals (BAs) have been frequently detected in riparian sediments, influencing the substance transformation in river ecosystems. However, there is still a lack of systematic investigation on the effects of MPs and BAs on sediment DOM. This study investigated the impact of MPs and BAs on the geochemical characteristics of DOM in riparian sediments and their microbial mechanisms. The results showed that MPs and BAs increased sediment DOC concentration by 34.24%∼232.97% and promoted the conversion of macromolecular components to small molecular components, thereby reducing the humification degree of DOM. Mathematical model verified that the changes of keystone microbes composition in sediments were direct factors affecting the characteristics of DOM in riparian sediment. Especially, MPs tolerant microbes, including Planctomicrobium, Rhodobacter, Hirschia and Lautropia, significantly increased DOC concentration and decreased humification degree (P < 0.05). In addition, MPs and BAs could also influence keystone microbes in sediments by altering the structure of microbial network, thereby indirectly affecting DOM characteristics. The study demonstrates the pollution behavior of MPs in river ecosystems and provides a basis for protecting the ecological function of riparian sediments from MPs pollution.

High salinity restrains microplastic transport and increases the risk of pollution in coastal wetlands

Microplastics (MPs) pollution in coastal wetlands has attracted global attention. However, few studies have focused on the effect of soil properties and structure on MP transport in coastal wetlands. Salinity is one of the most pivotal environmental factors and varies in coastal wetlands. Here, we conducted column experiments and employed fluorescent labeling combined with Derjaguin-Landau-Verwey-Overbeek (DLVO) theoretical calculations to reveal the vertical transport behavior of MPs. Specifically, we investigated the influence of five salinity levels (0, 0.035, 0.35, 3.5, and 35 PSU) on MP transport in different coastal wetlands soils and a sand through the X-ray photoelectron spectroscopy and nondestructive computed tomography technique. The results indicated that the migration capability of MPs in soils is significantly lower than in quartz sand, and that the migration capability varies depending on the soil type. This variability may be due to soil minerals and microporous structures providing numerous attachment sites for MPs and may be explained by the DLVO energy barrier of MP-Soil (6568-7767 KT) and MP-sand (5250 KT). Salinity plays a crucial role in modifying the chemical properties of pore water (i.e., zeta potential) as well as altering the soil elemental composition and pore structure. At 0 PSU, the maximum C/C0 of MPs through the sand, Soil 1, and Soil 2 transport columns were 37.86 ± 2.36 %, 23.96 ± 1.71 %, and 3.94 ± 0.68 %, respectively. When salinity increased to 3.5 PSU, MP mobility decreased by over 20 %. Additionally, a salinity of 35 PSU may alter the soil pore distribution, thereby changing water flow paths and velocities to constrain the migration of MPs in soils. These findings could provide valuable insights into understanding the environmental behavior and transport mechanisms of MPs, and lay a solid scientific basis for accurately simulating and predicting the fate of MPs in coastal wetland water-soil systems. We highlight the effect of salinity on the fate of MPs and the corresponding priority management of MPs risks under the background of global climate change.

Interaction of Pb(II) with microplastic-sediment complexes: Critical effect of surfactant

In this study, the impact of surfactants on the adsorption behavior of Pb(II) onto microplastics-sediment (MPs-S) complexes was investigated. Firstly, virgin polyamide (VPA) and polyethylene (VPE) were placed in Xiangjiang River sediment for six months to conduct in-situ aging. The results indicated that the biofilm-developed polyamide (BPA) and polyethylene (BPE) formed new oxygen-containing functional groups and different biofilm species. Furthermore, the adsorption capacity of Pb(II) in sediment (S) and MPs-S complexes was in the following order: S > BPA-S > VPE-S > VPA-S > BPE-S. The addition of sodium dodecyl benzenesulfonate (SDBS) promoted the adsorption of Pb(II), and the adsorption amount of Pb(II) increased with the higher concentration of SDBS, while adding cetyltrimethylammonium bromide (CTAB) showed the opposite result. The adsorption process of MPs-S complexes to Pb(II) was dominated by chemical adsorption, and the interaction between MPs-S complexes and Pb(II) was multilayer adsorption involving physical and chemical adsorption when the surfactants were added. Besides, the pH exerts a significant effect on Pb(II) adsorption in different MPs-S complexes, and the highest adsorption amount occurred at pH 6. Noteworthy, CTAB promoted the adsorption ability of Pb(II) when the exogenous FA was added. The binding characteristic of sediment endogenous DOM components and Pb(II) was influenced by the addition of MPs and surfactants. Finally, it confirmed that adsorption mechanisms mainly involve electrostatic and hydrophobic interaction. This study provides a new perspective to explore the environmental behaviors of Pb(II) by MPs and sediments with the addition of surfactants, which was conducive to evaluating the ecological risks of MPs and heavy metals in aquatic environments.

Polyethylene Terephthalate Microplastic Exposure Induced Reproductive Toxicity Through Oxidative Stress and p38 Signaling Pathway Activation in Male Mice

Polyethylene terephthalate (PET) is a type of polymer plastic that is often used to make plastic bags, bottles, and clothes. However, the waste of such plastic products is decomposed into microplastics (MPs), which are plastic fragments smaller than 5 mm, by various external forces such as wind, UV radiation, mechanical wear, and biodegradation. PET MPs have been widely detected in the environment and human tissue samples; however, the toxicity and mechanism of PET MPs in mammals are still unclear. In this study, we investigated the male reproductive toxicity of PET MPs and their underlying mechanism. A total of 80 male mice were orally exposed to 0.01, 0.1, and 1 mg/d of PET MPs (with a diameter of 1 μm) for 42 days. The results showed that 1 μm PET MPs induced different degrees of pathological damage to testicular tissues, decreased sperm quality, and increased the apoptosis of spermatogenic cells via oxidative stress and p38 signaling pathway activation. To further illustrate and verify the mechanistic pathway, oxidative stress was antagonized using N-acetylcysteine (NAC), and the activation of the p38 signaling pathway was blocked using SB203580. The results revealed that the male reproductive injury effects after exposure to PET MPs were significantly ameliorated. Specifically, the testicular tissue lesions were relieved, the sperm quality improved, and the apoptosis of spermatogenic cells decreased. These results demonstrated that PET MP exposure induced male reproductive toxicity through oxidative stress and the p38 signaling pathway. This study provides new insights into the reproductive toxicity of MPs in males, as well as valuable references for public health protection strategies.

Using machine learning to reveal drivers of soil microplastics and assess their stock: A national-scale study

The issue of microplastic (MP) contamination in soil is a significant concern. However, due to limited large-scale studies and stock assessments, our understanding of the drivers of their distribution and fate remains incomplete. To address this, we conducted a comprehensive study in China, collected MP data from 621 sites, and utilized machine learning techniques for analysis. Our findings revealed 9 key factors influencing the distribution of soil MPs, highlighting their nonlinear influence processes. Among these factors, atmospheric deposition emerged as the most dominant driver, while wind and precipitation could lead to the transformation of soil from a sink to a source of MPs. MP concentrations in Chinese soils vary from 1.4 to 4333.1 particles/kg, with human activities significantly affecting their distribution, resulting in higher concentrations in the east and lower concentrations in the west. The estimated MP stock in Chinese soils is 1.92 × 1018 particles, equivalent to a mass of 2.11-8.64 million tonnes. This stock alone surpasses that found in global oceans, making global soil the largest reservoir of MPs. Overall, this study enhances our understanding of the environmental behavior of MPs and provides valuable data and theoretical support for the prevention, control, and management of this contamination.

Distribution of microplastics in Lanzhou section of the Yellow River: Characteristics, ecological risk assessment, and factors analysis

Microplastic (MP) is an emerging pollutant that has attracted attention in the environmental field, and the research of MPs in freshwater systems needs to be strengthened. To characterize the MPs in surface water and sediments of the western urban river network, water and sediment samples were collected. The results showed that the abundance of MPs in the water body of the river network ranged from 7 to 172 n/L, whereas the abundance of MPs in the sediments ranged from 7 to 144 n/kg, and the average abundance in the dry season was significantly higher than that in the rainy season. The majority of MPs (83.67 %) were < 1 mm and fibrous. The most commonly identified types of MPs were PET and PP, while the color blue was frequently observed. MPs have the potential to vertically migrate in sediments, with size, shape, density, and hydrodynamic forces being the main factors that contribute to this process. Correlation analysis results revealed that anthropogenic and meteorological factors, including precipitation, atmospheric conditions, and population density, had a discernible impact on the abundance, size, and shape of MPs. The ecological risk of MPs was assessed using the Polymer Hazardous Index (PHI), Pollution Load Index (PLI), and Potential Ecological Risk Index (PERI) methods, and the results showed that the overall ecological risk of the Lanzhou section of the Yellow River was low. This study can provide a scientific basis for monitoring and risk assessment of emerging contaminants such as MPs in the river environment.

Significant influence of land use types and anthropogenic activities on the distribution of microplastics in soil: A case from a typical mining-agricultural city

Microplastics pollution in soil has become a prominent issue in the field of ecological environment. However, relevant data on the microplastics pollution characteristics in mining industry-agricultural soil ecosystems is still limited. In this study, an extensive investigation on the characteristics of microplastics pollution in typical mining-agricultural city soil was conducted, revealing abundances, features, and influencing factors of microplastics in five land use types including facility farmland (FF), traditional farmland (TF), residential land (RL), industrial land (IL), and grassland (GL). The results showed that the distribution of microplastics abundances exhibits a nonuniform pattern, and the highest microplastics abundance was found in FF (3738 ± 2097 items·kg-1) compared with the other four land use types of this study area. Moreover, the key polymers identified were polypropylene (PP) and polyethylene (PE) with a smaller size (<0.01 mm) accounting for the majority at ,45 %, primary colors of microplastics were transparent with the dominant shapes being fibers and fragments. Additionally, principal component analysis and cluster analysis characterized microplastics features across various land use patterns, revealing that agricultural plastic waste, irrigation, and fertilization may be the main the primary sources of agricultural microplastics, while domestic sewage, household waste (include construction waste), and mining transportation activities are the potential urban sources. Correlation analysis indicates a positive relationship between TN, TP, SOC, and the abundances of microplastics (P < 0.05), and a negative relationship between pH and microplastic abundances. Furthermore, Cd, Cu, and As exhibit a significant positive correlation with microplastic characteristics (P < 0.05). Notably, the distribution trends of Cd content and microplastic abundance are similar. Overall, comprehensive analysis of environmental dynamics on microplastics in agricultural soil in coal industrial cities is crucial for developing effective measures to prevent and control microplastic pollution.

Critical evaluation of hyperspectral imaging technology for detection and quantification of microplastics in soil

In this study, we critically evaluated the performance of an emerging technology, hyperspectral imaging (HSI), for detecting microplastics (MPs) in soil. We examined the technology's robustness against varying environmental conditions in five groups of experiments. Our findings show that near-infrared (NIR) hyperspectral imaging (HSI) effectively detects microplastics (MPs) in soil, though detection efficacy is influenced by factors such as MP concentration, color, and soil moisture. We found a generally linear relationship between the levels of MPs in various soils and their spectral responses in the NIR HSI imaging spectrum. However, effectiveness is reduced for certain MPs, like polyethylene, in kaolinite clay. Furthermore, we showed that soil moisture considerably influenced the detection of MPs, leading to nonlinearities in quantification and adding complexities to spectral analysis. The varied responses of MPs of different sizes and colors to NIR HSI present further challenges in detection and quantification. The research suggests pre-grouping of MPs based on size before analysis and proposes further investigation into the interaction between soil moisture and MP detectability to enhance HSI's application in MP monitoring and quantification. To our knowledge, this study is the first to comprehensively evaluate this technology for detecting and quantifying microplastics.

Traversing the prevalence of microplastics in soil-agro ecosystems: Origin, occurrence, and pollutants synergies

The ubiquity of plastics in modern life has made them a significant environmental concern and a marker of the Anthropocene era. The degradation of plastics results in the formation of microplastics (MPs), which measure 5 mm or less. The coexistence of MPs with other pollutants found in sludge, water treatment plant effluents, surface water, and groundwater, shapes the environmental landscape together. Despite extensive investigation, the long-term implications of MPs in soils remain uncertain, underscoring the importance of delving into their transportation and interactions with soil biota and other contaminants. The present article provides a comprehensive overview of MPs contamination in soil, encompassing its sources, prevalence, features, and interactions with soil flora and fauna, heavy metals, and organic compounds. The sources of MPs in soil agroecosystems are mulching, composting, littering, sewage sludge, irrigation water, and fertilizer application. The concentration of MPs reported in plastic mulch, littering, and sewage sludge is 503 ± 2760 items per kg-1, 4483 ± 2315 MPs/kg, and 11,100 ± 570 per/kg. The transport of MPs in soil agroecosystems is due to their horizontal and vertical migration including biotic and abiotic mobility. The article also highlighted the analytical process, which includes sampling planning, collection, purification, extraction, and identification techniques of MPs in soil agroecosystems. The mechanism in the interaction of MPs and organic pollutants includes surface adsorption or adhesion cation bridging, hydrogen bonding, charge transfer, ligand exchange, van der Waals interactions, and ion exchange.

The problem of anthropogenic microfibres in karst systems: Assessment of water and submerged sediments

A new worrying micropollutant threathens natural environments: the microfibres (MFs). Natural, regenerated and synthetic MFs have been detected in different environments, as well as in organisms. While synthetic MFs are generally detected in microplastic analyses, natural and regenerated MFs are not taken into account, or are wrongly considered plastics. They are generally considered biodegradable even if their degradation processes in ecosystems are poorly known. Their potential faster degradation could release toxic compounds, and their characteristics could led to a long-term accumulation in the environment. Understanding their dangerousness and the possible impact they could have on ecosystems is fundamental for environment conservation. We collected and investigated water and submerged sediment samples in different caves and springs of the Classical Karst Region (NE Italy), rich in protected habitats and species. MFs were analysed via microscopy and spectroscopy. MFs were found in all samples, highlighting pollution in surface and subterranean habitats of the karst system. MF concentration was higher in submerged sediments respect to waters, highlighting an accumulation of MFs over time. Big microfibres were less abundant, and MF amount increased with the decrease in the considered size. More than 80% of fibres were fluorescent under UV light. Fluorescent MFs were especially transparent, while non-fluorescent ones were mainly black and blue. Most MFs were cellulosic, and synthetic MFs represent only 15-22%, highlighting a significant gap between the MF composition detected in natural environments and the global production of synthetic textiles in recent times. Synthetic MFs were more abundant in waters. Our results improve the knowledge on micropollutants in karst environments, laying the foundations for future research. MF pollution monitoring in karst areas must become a priority for species protection, habitat conservation, and waters management, improving analyses on a larger number of aquatic environments, taking into account the ecological connections between surface and subterranean habitats.

Atmospheric deposition of microplastics at a western China metropolis: Relationship with underlying surface types and human exposure

The issue of atmospheric microplastic (AMP) contamination is gaining increasing attention, yet the influencing factors and human exposure are not well-understood. In this study, atmospheric depositions were collected in the megacity of Chengdu, China, to investigate the pollution status and spatial disparities in AMP distribution. The relationship between AMP abundance and underlying surface types was then analyzed with the aid of back trajectory simulation. Additionally, a probabilistic estimation of human exposure to AMP deposition during outdoor picnics was provided, followed by the calculation of AMP loading into rivers. Results revealed that the mean deposition flux ranged within 207.1-364.0 N/m2/d (14.17-33.75 μg/m2/d), with significantly larger AMP abundance and sizes in urban compared to rural areas. Areas of compact buildings played an important role in contributing to both fibrous and non-fibrous AMP contamination from urban to rural areas, providing new insight into potential sources of pollution. This suggests that appropriate plastic waste disposal in compact building areas should be prioritized for controlling AMP pollution. Besides, the median ingestion of deposited AMPs during a single picnic was 34.9 N/capita/hour (3.03 × 10-3 μg/capita/hour) for urban areas and 17.8 N/capita/hour (7.74 × 10-4 μg/capita/hour) for suburbs. Furthermore, the worst-case scenario of AMPs loading into rivers was investigated, which could reach 170.7 kg in summertime Chengdu. This work could contribute to a better understanding of the status of AMP pollution and its sources, as well as the potential human exposure risk.

Overview of the environmental risks of microplastics and their controlled degradation from the perspective of free radicals

Owing to the significant environmental threat posed by microplastics (MPs) of varying properties, MPs research has garnered considerable attention in current academic discourse. Addressing MPs in river-lake water systems, existing studies have seldom systematically revealed the role of free radicals in the aging/degradation process of MPs. Hence, this review aims to first analyze the pollution distribution and environmental risks of MPs in river-lake water systems and to elaborate the crucial role of free radicals in them. After that, the study delves into the advancements in free radical-mediated degradation techniques for MPs, emphasizing the significance of both the generation and elimination of free radicals. Furthermore, a novel approach is proposed to precisely govern the controlled generation of free radicals for MPs' degradation by interfacial modification of the material structure. Hopefully, it will shed valuable insights for the effective control and reduction of MPs in river-lake water systems.

The seasonal variation and ecological risk of microplastics in the Lower Ganges River, Bangladesh

Microplastic (MP) pollution has gained considerable attention in various ecosystems; however, it has received relatively less attention in freshwater-riverine environments than in other ecosystems. The Ganges River Delta, one of the world's most densely populated areas, is a potential source of MP pollution in the freshwater ecosystem. MPs were identified throughout the year in the lower Ganges River water. Seasonally, the highest abundance was observed during the monsoon (14.66 ± 2.06 MPs/L), followed by the pre-monsoon (13.46 ± 1.75 MPs/L) and post-monsoon (11.50 ± 0.40 MPs/L). Throughout the year, MP discharge was estimated at 4.12 × 1012 to 2.17 × 1013 MPs/year. Fourier transformed infrared spectroscopy identified plastic polymers in the water, like ethylene vinyl acetate, polystyrene, polypropylene, polyethylene, and nylon. Moderate contamination by MPs was assessed throughout the year. Significant correlations between MP abundance and both rainfall and discharge were observed. It is essential to implement preventative measures in the Ganges River Basin to mitigate MP pollution before the situation worsens. PRACTITIONER POINTS: Throughout the year, MP concentration ranged from 10.67 to 20.33 MPs/L The highest MP occurrence was observed in the monsoon season (14.66 ± 2.06 MPs/L) The lowest abundance was detected in the post-monsoon period (11.50 ± 0.40 MPs/L) There was a moderate level of MP contamination in the lower Ganges River water It was shown that discharge and rainfall were correlated with MP abundance.

Vertical distribution of microplastics in sediment columns along the coastline of China

At present, there has been relatively less coverage of microplastics (MPs) pollution in sediment columns, especially across a large geographical span. This study collected sediment columns across 11 provinces along the coastline of China for MPs pollution investigation. The study found higher MPs diversity (Simpson diversity index) in sediment columns than in surface sediments, mostly comprising fiber MPs with dominant transparent and blue colors. Lower MPs pollution was noted in mangrove reserves, while estuarine and coastal areas showed higher pollution levels. Spearman correlation analysis shows that vertical of MPs abundance significantly decreased with depth at 6 of 11 sites. Large-sized MPs with diverse colors in deeper sediments (>40 cm) suggests that burial processes may render MPs more resistant to degradation. Our research highlights varied MPs distribution in coastal sediment, aiding future marine MPs pollution prediction and assessment.

Navigating the nexus: climate dynamics and microplastics pollution in coastal ecosystems

Microplastics (MPs) pollution is an emerging environmental health concern, impacting soil, plants, animals, and humans through their entry into the food chain via bioaccumulation. Human activities such as improper solid waste dumping are significant sources that ultimately transport MPs into the water bodies of the coastal areas. Moreover, there is a complex interplay between the coastal climate dynamics, environmental factors, the burgeoning issue of MPs pollution and the complex web of coastal pollution. We embark on a comprehensive journey, synthesizing the latest research across multiple disciplines to provide a holistic understanding of how these inter-connected factors shape and reshape the coastal ecosystems. The comprehensive review also explores the impact of the current climatic patterns on coastal regions, the intricate pathways through which MPs can infiltrate marine environments, and the cascading effects of coastal pollution on ecosystems and human societies in terms of health and socio-economic impacts in coastal regions. The novelty of this review concludes the changes in climate patterns have crucial effects on coastal regions, proceeding MPs as more prevalent, deteriorating coastal ecosystems, and hastening the transfer of MPs. The continuous rising sea levels, ocean acidification, and strong storms result in habitat loss, decline in biodiversity, and economic repercussion. Feedback mechanisms intensify pollution effects, underlying the urgent demand for environmental conservation contribution. In addition, the complex interaction between human, industry, and biodiversity demanding cutting edge strategies, innovative approaches such as remote sensing with artificial intelligence for monitoring, biobased remediation techniques, global cooperation in governance, policies to lessen the negative socioeconomic and environmental effects of coastal pollution.

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.

Microplastic Contamination of Non-Mulched Agricultural Soils in Bangladesh: Detection, Characterization, Source Apportionment and Probabilistic Health Risk Assessment

Microplastic contamination in agricultural soil is an emerging problem worldwide as it contaminates the food chain. Therefore, this research investigated the distribution of microplastics (MPs) in agricultural soils without mulch at various depths (0-5, 5-10, and 10-15 cm) across different zones: rural, local market, industrial, coastal, and research areas. The detection of MP types and morphology was conducted using FTIR and fluorescence microscopy, respectively. Eight types of MPs were identified, including high-density polyethylene (HDPE), low-density polyethylene (LDPE), polypropylene (PP), polyethylene terephthalate (PET), polyvinyl chloride (PVC), polyvinyl fluoride (PVF), polyvinyl alcohol (PVA), and polytetrafluoroethylene (PTFE), with concentrations ranging from 0.6 ± 0.21 to 3.71 ± 2.36 MPs/g of soil. The study found no significant trends in MP concentration, with ranges of 0-2.1 ± 0.38, 0-2.87 ± 0.55, and 0-2.0 ± 0.34 MPs/g of soil at depths of 0-5 cm, 5-10 cm, and 10-15 cm, respectively. The highest MP quantity was recorded at 8.67 in coastal area, while the lowest was 6.44 in the local market area. Various MP shapes, e.g., fiber, film, pellet, fragment, and irregular, were observed across all layers. PCA suggested irrigation and organic manure as potential sources of MPs. The estimated concentrations of MPs possessed low non-carcinogenic and carcinogenic risks to the farming community of Bangladesh.

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.

Humic substance mitigated the microplastic-induced inhibition of hydroxyl radical production in riparian sediment

Hydroxyl radicals (·OH) generated during the flooding-drought transformation process play a vital role in affecting nutrient cycles at riparian zone. However, information on the processes and mechanisms for ·OH formation under the influence of microplastics (MPs) remains unclear. In this study, the effects of MPs on ·OH production from riparian sediments with different biomass [e.g., vegetation lush (VL) and vegetation barren (VB)] were studied. The results showed that presence of MPs inhibited the production of ·OH by 27 % and 7.5 % for VB and VL sediments, respectively. The inhibition was mainly resulted from the MP-induced reduction of the biotic and abiotic mediated Fe redox processes. Spectral analysis revealed that VL sediments contained more high-molecular-weight humic-like substances. Presence of MPs increased the abundances and activities of Proteobacteria, Acidobacteria and Actinobacteria, which were conducive to the changes in humification and polar properties of organic matters. The reduced humic- and fulvic-like substances were accumulated in the flooding period and substantially oxidized during flooding/drought transformation due to the enhanced MP-mediated electron transfer abilities, thus mitigated the MP-induced inhibition effects. Therefore, in order to better understanding the biogeochemical cycling of contaminants as influenced by ·OH and MPs in river ecosystems, humic substances should be considered systematically.

Effects of microplastics on the structure and function of bacterial communities in sediments of a freshwater lake

As an emerging pollutant, microplastics (MPs) cause widespread concern around the world owing to the serious threat they pose to ecosystems. In particular, sediments are thought to be the long-term sink for the continual accumulation of MPs in freshwater ecosystems. Polyethylene (PE) and polyethylene terephthalate (PET) have been frequently detected with large concentration variations in freshwater sediments from the lower reaches of the Yangtze River, one of the most economically developed regions in China, characterized by accelerated urbanization and industrialization, high population density and high plastics consumption. However, the impact of PE and PET on the sedimental bacterial community composition and its function has not been well reported for this specific region. Herein, PE and PET particles were added to freshwater sediments to assess the effects of different MP types on the bacterial community and its function, using three concentrations (500, 1500 and 2500 items/kg) per MP and incubations of 35, 105 and 175 days, respectively. This study identified a total of 68 phyla, 211 classes, 518 orders, 853 families and 1745 genera. Specifically, Proteobacteria, Chloroflexi, Acidobacteriota, Actinobacteriota and Firmicutes were the top five phyla. A higher bacterial diversity was obtained in control sediments than in the MP-treated sediments. The presence of MPs, whether PET or PE, had significant impact on the bacterial diversity, community structure and community composition. PICRUSt2 and FAPOTAX predictions demonstrated that MPs could potentially affect the metabolic pathways and ecologically functional groups of bacteria in the sediment. Besides the MP-related factors, such as the type, concentration and incubation time, the physicochemical parameters had an effect on the structure and function of the bacterial community in the freshwater sediment. Taken together, this study provides useful information for further understanding how MPs affect bacterial communities in the freshwater sediment of the lower reaches of the Yangtze River, China.

Probing the molecular interaction between photoaged polystyrene microplastics and fulvic acid

As emerging contaminants, microplastics (MPs) are becoming a matter of global concern, and they have complex interactions with dissolved organic matter (DOM) widely present in aqueous environments. Here, we investigate the molecular interactions between aged polystyrene microplastics (PS-MPs) and fulvic acid (FA) under neutral conditions using a series of analytical techniques. The structural changes of FA and the binding interactions of PS-MPs with FA at a molecular level were explored by fluorescence and FT-IR combined with two-dimensional correlation spectroscopy (2D-COS). Results showed that photoaging of PS-MPs changed the sequence of structural variations with FA. Atomic force microscopy-infrared spectroscopy (AFM-IR) strongly demonstrated that the surface roughness of both pristine and aged PS-MPs greatly increased after FA addition. Meanwhile, AFM-IR and Raman spectroscopy revealed a stronger interaction between aged PS-MPs and FA. The content of oxygen-containing functional groups in PS-MPs increased after aging and after binding with FA, and surface distribution of these functional groups also changed. XPS analyses indicated that the oxygen content in PS-MPs increased after the interaction with FA and the increase in oxygen content was even greater in aged PS-MPs. Overall, these research findings are useful to understand the environmental impacts of DOM-MPs interactions and to address the uncertainty of MPs aging effect on their environmental behavior in aquatic ecosystems.

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

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

Health assessment based on exposure to microplastics in tropical agricultural soil

Microplastic (MP) pollution of agricultural soils has caused global alarm over its widespread distribution and potential risks to terrestrial ecosystems and human health. This study assessed human health based on exposure to soil MPs through a comprehensive investigation of the factors influencing their occurrence and spatial distribution on Hainan Island, South China. The results showed that the abundance of soil MPs was 1128.6 ± 391.5 items·kg-1, whereas the normalized abundance of MPs based on using a power-law function was 19,261.4 items·kg-1. Regarding the extent of population exposure to agricultural soil MPs, the average daily exposure dose (pADD) model revealed that using mass as an indicator to assess the health risks associated with MP intake is more reliable than using abundance. However, abundance-based exposure assessments are also relevant because MPs with smaller particle sizes are more harmful to human health. Moreover, for adults, the normalized pADD values based on abundance and mass were 1.68E-02 item MPs·kg BW-1·d-1 and 7.23E-02 mg MPs·kg BW-1·d-1, respectively. Although the multidimensionality of MPs should be further aligned and quantified, the preliminary findings of this study contribute to the development of human health risk assessment frameworks for soil MPs.

Effects of naturally aged microplastics on the distribution and bioavailability of arsenic in soil aggregates and its accumulation in lettuce

Naturally aged microplastics (NAMPs) and arsenic (As) have been reported to coexist in and threaten potentially to soil-plant ecosystem. The research explored the combined toxic effects of NAMPs and As to lettuce (Lactuca sativa L.) growth, and the distribution, accumulation and bioavailability of As in soil aggregates. The As contaminated soil with low, medium and high concentrations (L-As, M-As, H-As) were treated with or without NAMPs, and a total of six treatments. The results displayed that, in comparison to separate treatments of L-As and M-As, the presence of NAMPs increased the total biomass of lettuce grown at these two As concentrations by 68.9 % and 55.4 %, respectively. Simultaneous exposure of NAMPs and L-As or M-As led to a decrease in As content in shoot (0.45-2.17 mg kg-1) and root (5.68-14.66 mg kg-1) of lettuce, indicating an antagonistic effect between them. In contrast, co-exposure to H-As and NAMPs showed synergistic toxicity, and the leaf chlorophyll and nutritional quality of lettuce were also reduced. NAMPs altered the ratio of different soil aggregate fractions and the distribution of bioavailable As within them, which influenced the absorption of As by lettuce. In conclusion, these direct observations assist us in enhancing the comprehend of the As migration and enrichment characteristics in soil-plant system under the influence of NAMPs.

Evaluation of microplastic pollution and risk assessment in a tropical monsoonal estuary, with special emphasis on contamination in jellyfish

Estuaries, which serve as vital links between land and coastal ecosystems, play a significant part in facilitating the transfer of plastic waste from the land to the ocean. In this research, we examined the prevalence, characteristics, and ecological risks of microplastics (MPs) in the extensively urbanized Cochin Estuarine System (CES), India. Additionally, it represents one of the initial evidence-based examinations of MPs ingestion by jellyfish in Indian waters, focusing on Acromitus flagellatus, Blackfordia virginica, and Pleurobrachia pileus species. The abundance of MPs found in the surface water of the Cochin Estuarine System (CES) varied between 14.44 ± 9 to 30 ± 15.94 MP/m3, with an average of 21.6 ± 11 MP/m3. In both surface waters and jellyfish from the Cochin Estuarine System (CES), fibers were the most prevalent type of MPs, with polyethylene (PE), polypropylene (PP), and polyamide (PA) being the most common polymer varieties. To evaluate the current levels of MPs and their effect on the CES, the Pollution Load Index (PLI), Potential Ecological Risk Index (PERI), and Polymeric Risk Index (H) were utilized. The high PLIestuary values (20.33), high Hestuary values (234.02), and extreme PERIestuary value (1646.06) indicate that the CES is facing an extreme ecological risk. Among the 280 jellyfish individuals examined, 118 (42.14%) were recognized to contain MPs with an average of 1.54 ± 2.68 MPs/individual. Pearson bivariate analysis revealed a significant correlation between the jellyfish bell size and number of plastics per individual. Comparison between jellyfish species revealed, the majority (66%) of the MPs identified in jellyfish were from A. flagellatus and 44 among the 50 jellyfish examined (88%) had MPs. These findings suggest that A. flagellatus may be a potential sink for MPs and may be utilized to be a bioindicator for monitoring MPs contamination in estuarine systems, aiding in future plastic pollution mitigation efforts.

Occurrence and distribution of microplastics in the adjacent environment of Yellow River Delta, China

In the precent study, the microplastics (MPs) pollution level was evaluated in diverse environmental samples from the Yellow River Delta. The results indicated that the abundance of MPs in water, sediment and soil samples ranged from 0.50 to 7.83 items·L-1, 200 to 4200 items·kg-1, and 100 to 1400 items·kg-1, respectively. Film form of MPs was dominant in water, while fiber MPs were dominant in both sediment and soil samples. In all samples, most MPs were < 1 mm in size. White was the main color in water, black was the main color in sediment and soil samples. The most common MPs type was polyethylene (33 %) in water, while rayon accounted for the majority of MPs in sediment (42 %) and soil (70 %) samples. The redundancy analysis results showed that MPs in water and sediment were more affected by water quality, while soil MPs were easily affected by landscape pattern.

Temperature-dependent effects of microplastics on sediment bacteriome and metabolome

The increasing prevalence of microplastics in the environment has become a concern for various ecosystems, including wetland ecosystems. Here, we investigated the effects of three popular microplastic types: polyethylene, polylactic acid, and tire particles at 5 °C and 25 °C on the sediment microbiome and metabolome at the 3% (w/w) level. Results indicated that temperature greatly influenced catalase and neutral phosphatase activities, whereas the type of microplastic had a more significant impact on urease and dehydrogenase activities. The addition of microplastic, especially tire particles, increased microbial diversity and significantly altered the microbial community structure and metabolic profile, leading to the formation of different clusters of microbial communities depending on the temperature. Nonetheless, the effect of temperature on the metabolite composition was less significant. Functional prediction showed that the abundance of functional genes related to metabolism and biogeochemical cycling increased with increasing temperature, especially the tire particles treatment group affected the nitrogen cycling by inhibiting ureolysis and nitrogen fixation. These observations emphasize the need to consider microplastic type and ambient temperature to fully understand the ecological impact of microplastics on microbial ecosystems.