Microplastics and Nanoplastics in Aquatic Environments: Aggregation, Deposition, and Enhanced Contaminant Transport

Photodegradation Controls of Potential Toxicity of Secondary Sunscreen-Derived Microplastics and Associated Leachates

The escalating environmental concern over secondary microplastics (SMPs) stems from their physicochemical evolution from primary microplastics (PMPs), yet the contribution of varying physicochemical transformations to the ultimate environmental risks remains unknown. In this study, a photomechanical degradation process was employed to convert the primary sunscreen-derived microplastics (SDMPs) into secondary SDMPs. While mechanical degradation caused physical fragmentation, photodegradation induced both physical and chemical alterations, introducing surface oxidation, chemical bond scission, and cross-linking to the secondary SDMPs. Employing a combination of alkaline digestion and pyrolysis GC-MS techniques, it was observed that both physical fragmentation and photooxidation led to heightened intracellular sequestration of MPs. Although the bioaccumulated SDMPs could be indicated by the enlarged lysosomes and fragmented mitochondria, toxicity of secondary SDMPs at the cellular level was primarily driven by chemical transformations post-photodegradation. A nontargeted analysis employing high-resolution mass spectrometry identified 46 plastic-associated compounds in the leachate, with photodegradation-induced chemical transformations playing a crucial role in the dissociation of hydrophobic additives and oxidative conversion of leached compounds. The toxicity of the leachate was exacerbated by photodegradation, with mitochondrial fragmentation serving as the primary subcellular biomarker, indicative of leachate toxicity. This study elucidates the pivotal role of photodegradation in augmenting the cytotoxicity of secondary SDMPs, shedding light on the intricate interplay between physicochemical transformations and environmental risks.

Reveal resistance mechanisms of Mirabilis jalapa L. when exposed to galaxolide and polystyrene microplastics stress, from individual, cellular and molecular level

As emerging contaminants, galaxolide (HHCB) and polystyrene microplastics (PSMP) are known to persist in the environment at low concentrations, posing significant ecological risks. While extensive research has focused on their ecotoxicological effects, limited attention has been given to plant tolerance mechanisms. This study investigates the tolerance and adaptive mechanisms of the ornamental plant Mirabilis jalapa L. (M. jalapa) to HHCB and PSMP exposure. Results demonstrated that M. jalapa exhibited robust tolerance to both pollutants, maintaining healthy growth in rhizomes and leaves, as evidenced by increased length and biomass. Exposure to PSMP and HHCB induced stomatal opening and enhanced transpiration, potentially mitigating pollutant toxicity. Both contaminants triggered oxidative stress, but M. jalapa activated defense mechanisms, as indicated by reduced malondialdehyde (MDA) levels and increased superoxide dismutase (SOD) activity, effectively regulating reactive oxygen species (ROS) and maintaining cellular homeostasis. Integrated metabolomic and transcriptomic analyses identified six co-annotated KEGG pathways, involving 11 key genes and 6 metabolites, revealing that M. jalapa employs adaptive energy metabolism and pollutant defense strategies to counteract HHCB and PSMP stress. These findings provide a theoretical foundation for utilizing M. jalapa in phytoremediation of HHCB and/or PSMP contamination.

Numeric uptake drives nanoplastic toxicity: Size-effects uncovered by toxicokinetic-toxicodynamic (TKTD) modeling

Predicting nanoplastic bioaccumulation and toxicity using process-based models is challenging due to the difficulties in tracing them at low concentrations. This study investigates the size-dependent effects of nanoplastic exposure on Daphnia magna using a toxicokinetic-toxicodynamic (TKTD) model. Palladium-doped fluorescent nanoplastics in three sizes (30-nm, 66-nm, 170-nm) were tested at two numeric exposure concentrations. The TK model reproduced nanoplastic uptake and elimination, indicating a uniform elimination rate constant (0.035 h-1) across sizes, while uptake rate constants (ku) varied by size and concentration. Fluorescence analysis revealed larger nanoplastics (66-nm, 170-nm) accumulated primarily in the intestine, while smaller nanoplastics (30-nm) were more widely distributed. Re-modeling uptake specifically for the intestine showed consistent trends in the uptake rate constants, with larger nanoplastics exhibiting higher ingestion efficiency. Toxicity effects mirrored the order of whole-organism nanoplastic uptake: 30-nm nanoplastics were most toxic, 170-nm nanoplastics showed slight toxicity, and 66-nm nanoplastics were non-toxic. The TD model suggested similar hazard potentials across sizes, with observed toxicity differences likely driven by whole-organism particle uptake. The TKTD model predicted no-effect concentrations at 1.8 × 1014 and 6.0 × 1014 particles L-1 for 30-nm and 170-nm nanoplastics, respectively, corresponding to mass concentrations of 2.54 and 1540 mg L-1. These values are significantly higher than reported environmental levels, indicating a low current toxicity risk to D. magna. Overall, this study enhances understanding of how size-dependent uptake behaviors influence nanoplastic toxicity, stressing the need for more accurate assessment of hazards linked to low-size nanoplastics and supporting more informed decision-making in nanoplastic pollution management.

Comparison of microplastics heteroaggregation with MoS2 and graphene oxide nanosheets: Dependence on the configuration and impacts on aquatic transport

Understanding the behavior and fate of microplastics (MPs) in aquatic environment is crucial for assessing their potential risks. This study investigated the heteroaggregation behaviors of MPs with representative 2D nanosheets, MoS2 and graphene oxide (GO), under various conditions, focusing on the transport behavior of the resulting aggregates. It was found that the destabilization capabilities of 2D nanosheets are notably stronger than those of well-reported nanoparticles. More importantly, the deposition and transport of MPs are highly dependent on the configuration of the resulting aggregates. MoS2 nanosheets conformally coat MPs, forming compact and colloidally stable complexes that completely alter the MPs' surface to the negatively charged MoS2. The interaction resulted in high mobility and minimal deposition in environmental matrices. In contrast, GO nanosheets bridge MPs into large clusters, reducing transport and increasing deposition. This difference in aggregate configuration is attributed to the distinct interactions between the nanosheets and MPs: rigid MoS2 nanosheets adhere via strong van der Waals forces, while GO, with oxygen functional groups on its edges and surfaces, folds and crosslinks between particles upon adsorption. These findings underscore the critical role of 2D materials in shaping the environmental fate of MPs, advancing our knowledge on the aggregation process.

Microplastics in municipal solid waste landfill leachate and their removal in treatment units: A perspective of controlled and uncontrolled landfills

Leachate produced from municipal solid waste landfill serves as a potential pathway for microplastics (MPs) release into the environment with a high potential for soil, surface water, and groundwater contamination. These MPs not only persist for longer duration of time in the landfill but also interact with toxic chemical contaminants. These interactions arise from the hydrophobic characteristics and minuscule size of MPs, which absorb a variety of emerging toxic contaminants present in these systems thereby amplifying the risk to surrounding environment. This study was performed to investigate the abundance, characteristics, and pollution risk of MPs in leachate from two contrasting landfill systems in the cities of Chandannagar and Baidyabati, India. A total of 8 leachate samples from an uncontrolled landfill (UCL), i.e., open dump, and 24 samples from different leachate treatment units (LTUs) of a controlled landfill (CL) were evaluated. Particle sizes of 1-5 mm (41.9%) in UCL and 0.025-0.5 mm (46.2%) in CL were predominant. Seven different types of polymers were identified in untreated leachate samples from UCL having concentration 53.4 ± 6.69 p/L (mean ± standard deviation) and in CL 34.7 ± 4.73 p/L. The predominant shapes were films, fragments, and fibers in UCL, whereas fragments and fibers dominated in CL. Polyethylene and polypropylene were the most frequent types of polymers observed in both sites. In CL, collection well, aeration lagoon, and sedimentation pond were used for LTUs, in which overall 83.3% MPs removal was achieved. High removal in LTUs highlights the importance of engineered systems for leachate management. However, optimization of these units is needed for enhanced removal of particles <0.5 mm. For UCL the findings suggest urgent need for implementing basic containment and treatment systems, particularly given their higher pollution risk indices. Varying landfill designs, waste compositions, and weather conditions of specific locations restrict generalisation of the findings to other regions. Therefore, long-term monitoring studies across different geographical and climatic conditions are recommended to develop more comprehensive management strategies.

Microplastic types dominate the effects of bismuth oxide semi-conductor nanoparticles on their transport in saturated quartz sand

The transport of microplastics (MPs) is of great significance due to its potential threat to subsurface systems. The copresence of MPs and semi-conductor nanoparticles is quite common in practical environments (i. e. in electronic/electrical waste disposal sites). To date, the influence of bismuth oxide (Bi2O3) semi-conductor nanoparticles on MPs transport in porous media has still been rarely and explicitly explored. Therefore, the effect of Bi2O3 on the transport of distinct types of MPs were investigated using column experiments. The MPs included 0.51 μm and 1.1 μm polystyrene (PS), 1 μm polyethylene terephthalate (PET) and 1 μm polyethylene (PE) MPs. Mechanisms for the differently altered transport of various MPs with Bi2O3 were further elucidated. It was verified that the deposited Bi2O3 on sand surfaces could contribute to the decreased transport of PET and PE MPs by column experiments with pre-treatment. Moreover, scanning electron microscopy (SEM), dynamic light scattering (DLS) measurements, and electrochemical Nyquist curves demonstrated that the interaction of PE and PET MPs with Bi2O3 was more pronounced than that of PS MPs, especially for PE MPs. In addition, density functional theory (DFT) calculations combined with adsorption experiments further confirmed that the adsorption between PE MPs and Bi2O3 was the strongest, which then contributed to the highest decrease of PE MPs transport. This study highlighted that the MPs types might be the major factor controlling its interaction with copresent substances, thereby affecting its fate and transport in soil systems.

Dynamic changes of leachates of aged plastic debris under different suspended sand concentrations and their toxicity

Plastic pollution in aquatic environments poses significant ecological risks, particularly through released leachates. While traditional or non-biodegradable plastics (non-BPs) are well-studied, biodegradable plastics (BPs) have emerged as alternatives that are designed to degrade more rapidly within the environment. However, research on the ecological risks of the leachates from aged BPs in aquatic environments is scarce. This controlled laboratory study investigated the leachate release processes and associated toxicity of traditional non-BPs, i.e., polyethylene terephthalate (PET) and polypropylene (PP) and BPs, i.e., polylactic acid (PLA) combined with polybutylene adipate terephthalate (PBAT) and starch-based plastic (SBP) under different aging time and suspended sand concentrations (0, 50, 100, 250, and 500 mg/L). The results indicated that BPs release significantly higher levels of dissolved organic carbon (DOC) than those of non-BPs, particularly at elevated suspended sand concentrations. The DOC concentrations in PLA+PBAT leachate reached 2.69 mg/L, surpassing those of PET and PP. Additionally, BPs released organic matter of larger molecular weight and protein-like substances. Toxicity tests showed that leachates from BPs inhibited the activity of Daphnia magna more than those from non-BPs. At a suspended sand concentration of 500 mg/L, PLA+PBAT leachate caused a 30 % inhibitory rate of Daphnia magna. Despite enhanced degradability, leachates from BPs may pose increased environmental risks in ecosystems with high suspended sand concentrations. Comprehensive ecological risk assessments are essential for effectively managing and mitigating these hazards of plastic pollution.

Micro- and Nano-Plastic-Induced Adverse Health Effects on Lungs and Kidneys Linked to Oxidative Stress and Inflammation

Micro- and nano-plastics (MNPs) are small plastic particles that result from the breakdown of larger plastics. They are widely dispersed in the environment and pose a threat to wildlife and humans. MNPs are present in almost all everyday items, including food, drinks, and household products. Air inhalation can also lead to exposure to MNPs. Research in animals indicates that once MNPs are absorbed, they can spread to various organs, including the liver, spleen, heart, lungs, thymus, reproductive organs, kidneys, and even the brain by crossing the blood-brain barrier. Furthermore, MPs can transport persistent organic pollutants or heavy metals from invertebrates to higher levels in the food chain. When ingested, the additives and monomers that comprise MNPs can disrupt essential biological processes in the human body, thereby leading to disturbances in the endocrine and immune systems. During the 2019 coronavirus (COVID-19) pandemic, there was a significant increase in the global use of polypropylene-based face masks, leading to insufficient waste management and exacerbating plastic pollution. This review examines the existing research on the impact of MNP inhalation on human lung and kidney health based on in vitro and in vivo studies. Over the past decades, a wide range of studies suggest that MNPs can impact both lung and kidney tissues under both healthy and diseased conditions. Therefore, this review emphasizes the need for additional studies employing multi-approach analyses of various associated biomarkers and mechanisms to gain a comprehensive and precise understanding of the impact of MNPs on human health.

Methodologic insights aimed to set-up an innovative Laser Direct InfraRed (LDIR)-based method for the detection and characterization of microplastics in wastewaters

Wastewater treatment plants (WWTPs) are generally reported to be effective in removing microplastics (MPs). Nevertheless, the lack of standardized methodologies for their counting and characterization hinders direct comparison across literature reports, limiting the establishment of reliable benchmarks. In this perspective, this work aimed to provide methodological insights on a feasible approach for detecting and characterizing MPs in both raw and treated wastewater by exploiting the innovative Laser Direct InfraRed (LDIR) technique. MPs of various polymeric nature, size and shape were specially produced and used to fine-tune and validate a LDIR-based method for both their chemical identification and size/morphology description, while well-established techniques were employed to evaluate the reliability of collected data. The robustness of the tailored protocol was then assessed through a monitoring campaign conducted at a large municipal WWTP in Tuscany (Italy), for which an average MPs removal efficiency of 82 % was estimated. Various polymers were detected in the processed samples, with a high relative content of cellulose-based materials in both influent and effluent (32 % and 54 % of particles, respectively). Most MPs had a characteristic size lower than 100 μm, with particles <30 μm representing about 45 % and 29 % of MPs in the influent and effluent, respectively. MPs were in the form of fibers (25-39 %), fragments (32-43 %) and pellets (29-32 %). The consistency of the obtained results suggested the robustness and reliability of the proposed LDIR-based method, highlighting its potential for more in-depth monitoring of MPs in WWTPs.

Revealing Microplastic risks in stratified water columns of the East China Sea offshore

Microplastics have been proven to impact a broad range of marine species significantly. This study investigated the vertical distribution characteristics of microplastics (MPs) to verify their potential toxicity, distribution patterns, and affecting probability on organisms offshore of the East China Sea (ECS), China. Significant variations in MP characteristics across stratified water layers were identified and corroborated through artificial neural network (ANN) analysis. By a combination of species sensitivity distribution (SSD), risk quotient (RQ) and joint probability curves (JPC) method, this study gave the regional risk thresholds and current risk distributions. Based on SSD, the derived predicted no-effect concentration for the ecosystem was 52.0 items/L (95 % confidence interval: 13.7-262.8 items/L), with the 5 % species hazardous concentration at 103.6 items/L. The RQ assessment results indicated varying ecological risk levels across different water layers, with the highest risks transitioning from north to south and from surface to bottom layers. Most sites exhibited a moderate risk level, with the highest risks identified in surface water near the Yangtze River Estuary, China. Conversely, the JPC analysis suggested a minimal ecological risk across the study area, emphasizing variable ecological risk contingent on species presence. This study underscores the importance of examining surface and intermediate water layers for marine habitats and organisms, highlighting the necessity of prioritizing investigations into the distribution of MPs across different water layers in the ECS, particularly focusing on buoyant polyester fibers present in the upper water column and the layers beneath the offshore surface.

Microplastic migration and transformation pathways and exposure health risks

Plastics play a crucial role in modern life, but improper use and disposal have resulted in microplastics becoming widespread in the environment, raising significant concerns about both the environment and human health. Extensive research has explored the transformation mechanisms, bioaccumulation, ecological impacts, and health risks associated with microplastics. The present review first analyzes the migration, transformation, and degradation pathways of microplastics on a global scale, and then synthesizes current knowledge on the types, sources, and migration pathways of microplastics in soil, atmosphere, and aquatic environments, emphasizing transformation mechanisms like photo-aging and microbial degradation, and detailing their ecological and human health impacts. Additionally, this review examines gaps in current research and identifies critical areas needing further study, such as key control points in microplastic degradation processes and the mechanisms underlying health risks to populations. The aim is to provide a comprehensive reference for advancing microplastic pollution control, ecological protection efforts, and health risk assessment frameworks.

Antibiotic resistance genes in anaerobic digestion: Unresolved challenges and potential solutions

Antimicrobial resistance (AMR) threatens public health, necessitating urgent efforts to mitigate the global impact of antibiotic resistance genes (ARGs). Anaerobic digestion (AD), known for volatile solid reduction and energy generation, also presents a feasible approach for the removal of ARGs. This review encapsulates the existing understanding of ARGs and antibiotic-resistant bacteria (ARB) during the AD process, highlighting unresolved challenges pertaining to their detection and quantification. The questions raised and discussed include: Do current ARGs detection methods meet qualitative and quantitative requirements? How can we conduct risk assessments of ARGs? What happens to ARGs when they come into co-exposure with other emerging pollutants? How can the application of internal standards bolster the reliability of the AD resistome study? What are the potential future research directions that could enhance ARG elimination? Investigating these subjects will assist in shaping more efficient management strategies that employ AD for effective ARG control.

Synergistic neurotoxicity of clothianidin and photoaged microplastics in zebrafish: Implications for neuroendocrine disruption

Microplastics (MPs), widely found in aquatic environments, pose a growing threat to environmental and biological health due to their complex interactions with pollutants and microorganisms. This study investigates the adsorption characteristics of clothianidin (CLO) on polystyrene (PS) and photoaged polystyrene (P-PS) and explores the neurotoxic effects of CLO combined with PS/P-PS in larval zebrafish (Danio rerio). Adsorption kinetics and isotherms showed that P-PS exhibited a higher adsorption capacity and faster equilibrium compared to PS, indicating the significant role of photoaging in enhancing CLO adsorption. Exposed to CLO combined with PS/P-PS resulted in reduced locomotor activity, particularly in the P-PS + CLO group, suggesting amplified neurotoxicity due to P-PS. Analysis of the hypothalamic-pituitary-interrenal (HPI) axis revealed elevated levels of adrenocorticotropic hormone (ACTH) and cortisol, along with downregulated expression of stress-related genes in co-exposed zebrafish, indicating disruption of neuroendocrine function. Neurotransmitter analysis showed significant changes in acetylcholine (ACh), dopamine (DA), serotonin (5-HT), and γ-aminobutyric acid (GABA) levels, further confirming the neurotoxic impact of co-exposure. The findings highlight the synergistic neurotoxicity of CLO and photoaged MPs, with potential implications for aquatic ecosystems. This study advances the field of environmental science by addressing critical knowledge gaps in pollutant-microplastic interactions, providing a foundation for developing targeted mitigation strategies and enhancing ecological risk management frameworks.

Molecular modeling to elucidate the dynamic interaction process and aggregation mechanism between natural organic matters and nanoplastics

The interactions of nanoplastics (NPs) with natural organic matters (NOMs) dominate the environmental fate of both substances and the organic carbon cycle. Their binding and aggregation mechanisms at the molecular level remain elusive due to the high structural complexity of NOMs and aged NPs. Molecular modeling was used to understand the detailed dynamic interaction mechanism between NOMs and NPs. Advanced humic acid models were used, and three types of NPs, i.e., polyethylene (PE), polyvinyl chloride (PVC), and polystyrene (PS), were investigated. Molecular dynamics (MD) simulations revealed the geometrical change of the spontaneous formation of NOMs-NPs supramolecular assemblies. The results showed that pristine NPs initially tend to aggregate homogeneously due to their hydrophobic nature, and then NOM fragments are bound to the formed NP aggregates mainly by vdW interaction. Homo- and hetero-aggregation between NOMs and aged NPs occur simultaneously through various mechanisms, including intermolecular forces and Ca2+ bridging effect, eventually resulting in a mixture of supramolecular structures. Density functional theory calculations were employed to characterize the surface properties and reactivity of the NP monomers. The molecular polarity indices for unaged PE, PS, and PVC were 3.1, 8.5, and 22.2 kcal/mol, respectively, which increased to 43.2, 51.6, and 42.2 kcal/mol for aged NPs, respectively, indicating the increase in polarity after aging. The vdW and electrostatic potentials of NP monomers were visualized. These results clarified the fundamental aggregation processes, and mechanisms between NPs and NOMs, providing a complete molecular picture of the interactions of nanoparticles in the natural aquatic environment.

Ocean plastic pollution: a human and biodiversity loop

This study offers an updated analysis of the effects of ocean plastic accumulation on human health and biodiversity within the food chain, covering the period from 2018 to 2023. Through a comprehensive review of relevant literature, a framework has been developed to visually illustrate the progression of plastics through the food chain. This framework emphasizes the intricate connections among four key elements: humans, plastics, biodiversity, and the food chain. By examining the cycle of challenges encountered during the phases of production, consumption, and disposal, the research reveals how these stages are interrelated. This perspective not only delineates the complexities involved but also identifies potential solutions, particularly by incorporating circular economy principles. Consequently, the study highlights the importance of understanding the impact of plastics on the food chain while proposing strategies grounded in circular economy concepts to mitigate plastic pollution throughout the three stages.

Evaluating Toxic Interactions of Polystyrene Microplastics with Hazardous and Noxious Substances Using the Early Life Stages of the Marine Bivalve Crassostrea gigas

Plastics pose a significant threat to marine ecosystems, owing to their slow biodegradability. Microplastics (MPs), in particular, affect marine life and maricultural organisms and can enter the food chain via ingestion by marine organisms, leading to bioaccumulation in predators, including humans. This study assessed the toxic interactions between polystyrene microplastic particles (PSMPs) and cadmium (Cd) and phenanthrene (Phe) using marine bivalves. While PSMPs were non-toxic to Pacific oysters (Crassostrea gigas), the toxicity of Cd and Phe was concentration-dependent. In most conditions, PSMPs reduced the toxicity of Cd and Phe, but in simultaneous exposure, they acted as Cd messengers, altering the toxicity during the adult stage. This study confirms that PSMPs can interact with coastal environmental pollutants, thereby accelerating biotoxicity and posing a significant threat to marine wildlife, mariculture, and human health. It also highlights the need to assess MP toxicity in coastal environments and their interactions with pollutants.

Size-dependent dynamics and tissue-specific distribution of nano-plastics in Danio rerio: Accumulation and depuration

Nano-plastics (NPs), defined as particles smaller than 1 µm, have emerged as a significant environmental contaminant due to their potential ecological impacts. This study explores the size-dependent dynamics and tissue-specific distribution of polystyrene nano-plastics (PS-NPs) in Danio rerio exposed to PS-NPs at an environmentally relevant concentration of 1 μg/mL for 28 days, followed by a 17-day depuration period. PS-NPs of 20, 100, 200, and 500 nm were assessed in the intestine, liver, gills, muscle, and brain using transmission electron microscopy (TEM) and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). Smaller PS-NPs (20 nm) showed the highest accumulation in the intestine, followed by the liver, and gills, due to their greater surface area and cellular penetration. In contrast, larger PS-NPs (500 nm) exhibited lower accumulation and clearance rates, especially in the brain, suggesting restricted passage through biological barriers. The intestine consistently had the highest concentrations in both accumulation and depuration, while the brain maintained the lowest across all nanoparticle sizes. During depuration, smaller particles cleared more quickly, whereas larger particles persisted. This study highlights the tissue-specific distribution and retention patterns of PS-NPs in D. rerio, providing insights into nanoparticle behavior in aquatic organisms and the need for long-term size-specific environmental risk assessments.

Distribution and Biological Response of Nanoplastics in Constructed Wetland Microcosms: Mechanistic Insights into the Role of Photoaging

Concern over nanoplastic contamination of wetland ecosystems has been increasing. However, little is known about the effect of photoaging on the distribution and biological response of the nanoplastics. Here, palladium-labeled polystyrene nanoplastics (PS-Pd NPs) at 0.05-50 mg/L were exposed to constructed wetland microcosms containing floating (Eichhornia crassipes) and submerged (Vallisneria natans) macrophytes. Results demonstrate that PS-Pd NPs' concentration in surface water after 2-4 weeks of exposure was decreased by over 98.4% as compared with that in the 1st week. Photoaging enhanced the surface charge and colloidal stability of PS-Pd NPs, with a subsequent increase of the content of PS-Pd NPs in surface and middle layer water by 264.6 and 207.4%, respectively. Additionally, photoaging significantly enhanced the accumulation of PS-Pd NPs in E. crassipes roots by 6.9-65.0% and significantly decreased it in V. natans shoots by 59.7-123.0%. PS-Pd NPs inhibited the growth of V. natans by 43.8% at 50 mg/L. Mechanistically, PS-Pd NPs induced oxidative stress in V. natans, leading to the disruption of the metabolic pathway. Interestingly, PS-Pd NP exposure inhibited nitrification in wetland ecosystems due to the alteration of the related bacterial community (Ellin6067 decreased by 13.19%). These findings deepen our understanding of the environmental fate and risk of plastic particles in wetland ecosystems.

Study on Rapid Quantitative Detection of Soil MPs Based on Terahertz Time-Domain Spectroscopy

The presence of microplastics (MPs) in agricultural soils substantially affects the growth, reproduction, feeding, survival, and immunity levels of soil biota. Therefore, it is crucial to investigate fast, effective, and accurate techniques for the detection of soil MPs. This work explores the integration of terahertz time-domain spectroscopy (THz-TDS) techniques with machine learning algorithms to develop a method for the classification and detection of MPs. First, THz spectral image data were preprocessed using moving average (MA). Subsequently, three classification models were developed, including random forest (RF), linear discriminant analysis, and support vector machine (SVM). Notably, the SVM model had an F1 score of 0.9817, demonstrating its ability to rapidly classify MPs in soil samples. Three regression models, namely, principal component regression (PCR), RF, and least squares support vector machine (LSSVM), were developed for the detection of three MPs polymers in agricultural soils. Six feature extraction methods were used to extract the relevant parts of the data containing key information. The results of the study showed that the regression accuracies of PCR, RF, and LSSVM were greater than 83%. Among them, the RF had the highest overall regression accuracy. Notably, PE-UVE-RF had the best performance with Rc2, Rp2, root mean square error of calibration, and root mean square error of prediction values of 0.9974, 0.9916, 0.1595, and 0.2680, respectively. Furthermore, this model gets a better performance by hypothesis testing and predicting real samples.

Nanoplastic in aqueous environments: The role of chemo-electric properties for nanoplastic-mineral interaction

Due to increasing plastic production, the continuous release of primary and secondary nanoplastic particles (NPs, <1 μm) has become an emerging contaminant in terrestrial environments. The fate and transport of NPs in subsurface environments remain poorly understood, largely due to the complex interplay of mineralogical, chemical, biological, and morphological heterogeneity. This study examines interactions between abundant subsurface minerals and NPs under controlled water chemistry (1 mM KCl, pH 5.5). These conditions minimize potential chemical effects from ions in solution, isolating the impact of mineral complexity. Surface-modified polystyrene nanoparticles (-COOH and -NH2 functional groups) are proxies for degradation products and organic associations found in environmental plastics. Experimental results are compared with theoretical predictions using DLVO (Derjaguin-Landau-Verwey-Overbeek) double-layer force models. Despite all studied minerals maintaining negative surface charges across varying pH, electrostatic double-layer (EDL) interactions played a minor role in NP attachment. Instead, mechanisms such as specific ion-binding interactions (mediated by trace metal ions), bridging via divalent ions, and hydrogen bonding were more significant. Evidence suggests that kinetic effects for most mineral-NP combinations persist beyond 24 h. This study highlights the critical role of biogeochemical and mineralogical composition in controlling NP attachment and release in subsurface environments, with implications for their transport and fate in aquifers.

The vertical transport and fate of MPs-oil composite pollutants in nearshore environment

MPs-oil composite pollutants interact with particles to form MPs-oil-particles aggregates (MOPAs) in nearshore environment. In this study, we investigated vertical transport and fate of MPs-oil composite pollutants mediated by particles under various time scales, proposed and elucidated associated mechanisms. Majority of MPs with -CH2 suspended in water columns and particles with Si-O and O-H adsorbed MPs-oil composite pollutants in sediment phase, which caused differences in morphology structure and composition. The MOPAs with spherical or irregular three-dimensional in water columns can transport to sediment phase, resulting in more than 79 % lamellar MOPAs and more than 63 % oil in sediment phase. Besides, we demonstrated that degraded small-sized MPs-oil composite pollutants can resuspend into water columns. The mass of n-alkanes in sediment phase (< 45 μg) was lower than in water columns (< 120 μg) during degradation process. More importantly, during the intermediate stage of degradation, the size of oil droplets on surface of MPs decreased and particles trapped them to sediment phase, resulting in a V-shaped curve of mass changes of C14-C35 in water columns. Our research fills the gap in the field of MPs-oil composite pollutants in water columns and sediment phase, which can provide theoretical support for their disposal.

Microplastics Settling in Turbid Water: Impacts of Sediments-Induced Flow Patterns on Particle Deposition Rates

When microplastics (MPs) enter water bodies, they undergo various transport processes, including sedimentation, which can be influenced by factors such as particle size, density, and interactions with other particles. Surface waters contain suspended natural particles (e.g., clay and silt), which may impact MP settling rates. Here, we investigated how the presence of suspended sediments (SS) influenced the deposition patterns and rates of MPs in turbid waters. We systematically analyzed the settling velocities of particles, including different MP sizes and SS concentrations, in a plexiglass column with a camera array. For each experimental variant, we collected data on thousands of individual MPs, strengthening the statistical analysis of the particles' velocities. Simultaneous measurements of the SS flow and MPs trajectories revealed that the SS induced complex flow patterns, with MPs spending more time in downwelling flow regions, thereby accelerating MPs sedimentation. This effect was more pronounced when SS were aggregated. Additionally, we found that smaller MP fragments were more affected by the fluctuations than spheres or larger fragments. Collectively, our results provide valuable data for future MP fate models and help to understand the sedimentation processes of MPs in natural waters, which is crucial for assessing their environmental transport and impact.

Genotoxic and cytotoxic effects of polystyrene nanoplastics on human lymphocytes: A comprehensive analysis

A growing amount of plastic waste is finding its way into natural ecosystems as a result of the widespread usage of plastics in modern society. These wastes degrade physically and biologically over time, transforming into microplastics (MPs) and nanoplastics (NPs). MPs and NPs emissions from the terrestrial environment then mix with rivers and eventually the seas, forming garbage. The cytotoxic and genotoxic effects of 50 nm polystyrene nanoplastics (PsNP) on human lymphocytes were assessed using the in vitro mitotic index (MI), micronucleus (MN), and comet assays. Both 24 and 48-h applications were performed for MI, and it was determined that 50 nm PsNP provided a statistically significant decrease in MI compared to the control at all concentrations and application times (except 0.001 and 0.1 μg/mL at 24 h). According to the MN test results, the MN frequency increased significantly at all concentrations when compared to the negative control. In the comet test, a statistically significant increase of comet tail length was observed at 0.001, 10 and 100 μg/mL concentration with 50 nm PsNP exposure. Tail moment also showed a statistically significant increase at the lowest concentration of 0.001 μg/mL and the highest concentration of 1, 10, 100 μg/mL compared to the negative control. All test results show that PsNP has both genotoxic and cytotoxic potential.

Tracing microplastics in marine fish: Ecological threats and human exposure in the Bay of Bengal

This research on microplastics (MPs) in marine environments, particularly in Bay of Bengal fish, underscores the limited comprehension of their accumulation and potential health and environmental consequences. The study investigated the abundance of MPs in the organs of nine marine fish species from the north Bay of Bengal, assessing their polymeric risks and implications for human health. The average MPs ingested by each individual was 32.9 ± 3.0 items/ind.10 g-1 predominantly fibers (93.1 %), followed by fragments (6.1 %), with black being the most common color (76.3 %). The primary polymers identified were polyvinyl alcohol (PVA) (19.4 %), polyether sulfone (PES) (10.7 %), polyamide PA (8.7 %), acrylic, and polyethylene (PE), in the 500-5000 (80 %) μm size range. A moderate negative correlation with strong statistical significance was found with girth sizes and MPs concentration of average (Pearson's r = -0.5728, p < 0.0001). Body weight exhibited moderate negative correlations with MPs abundance in fish tissues (Pearson's r = -0.4701, p < 0.0001). Movement behavior analysis showed a negative correlation between MPs in fish tissues and depth range (Pearson's r = -0.4231, p < 0.0001). Demersal species contained more MPs than pelagic species, and carnivorous fishes had higher MPs levels than omnivorous and planktivorous fishes. The contamination factors (CF), pollution load index (PLI), and polymeric hazard index (PHI) were high and associated with untreated industrial and municipal wastewater sources. The estimated daily intake (EDI) of MPs for adults and children indicates significant health risks. The study improves our comprehension of MPs contamination, providing a significant reference for the appropriate governance, tracking, and reducing pollutants in marine animals in coastal waters.

Biodegradable microplastics adsorb more Cd than conventional microplastic and biofilms enhance their adsorption

Biodegradable polylactic acid (PLA) mulch has been developed to replace conventional polyethylene (PE) mulch in agriculture to reduce plastic pollution and the accumulation of microplastics (MPs) in soil. Cadmium (Cd) is a significant soil contaminant, and can be adsorbed by MPs. It is increasingly recognised that in the natural environment biofilms can develop on MPs and that this can affect their adsorption properties. We exposed PLA and PE mulches outdoors for 16 months. MPs were then generated from pristine and weathered mulches. Biofilms developed on the weathered plastics. Oxygen-containing functional groups were detected on the weathered, but not the pristine PE, abundance of these groups increased for the weathered PLA. After removal of the biofilm the observed increases in oxygen-containing functional groups relative to the pristine plastics remained. In adsorption experiments pristine PLA MPs had a greater maximum adsorption capacity than pristine PE MPs (106-126 vs 23.2 mg/kg) despite having a lower specific surface area (0.325 m2/g vs 1.82 m2/g) suggesting that the greater levels of adsorption were due to MP chemistry. The weathered plastics adsorbed more Cd than the pristine plastics (e.g. maximum adsorption capacities of 153-185 and 152 mg/kg for the weathered PLA and PE respectively). However, after removal of the biofilm, adsorption of Cd to the weathered MPs was no greater than for the pristine plastics. This suggests that the increased adsorption of Cd due to weathering was caused primarily by adsorption onto the biofilm.

Microplastic and nanoplastic pollution: Assessing translocation, impact, and mitigation strategies in marine ecosystems

The widespread presence of plastic debris in marine ecosystems was first highlighted as a serious concern in the United Nations Convention on the Law of the Sea (UNCLOS) and the 1972 London Convention. This realization identified plastic pollution as one of the major global environmental issues. Majorities of plastic debris are neither recycled nor incinerated, as a result, it eventually makes its way into lakes, rivers, and oceans. Analysis of water and sediment worldwide indicates that microplastics and nanoplastic are ubiquitous in soils, freshwater, and marine ecosystems. Microplastic and nanoplastics are distributed throughout marine environments via processes such as biofouling and chemical leaching, contaminating both pelagic and benthic species. Despite growing recognition of the hazards posed by microplastics and nanoplastics, regulatory efforts remain hampered by limited understanding of their broader ecological impacts, particularly how diverse factors translate into population declines and ecosystem disruptions. This review examines the pathways of microplastic and nanoplastic pollution, their interactions with other environmental stressors such as climate change and chemical pollution, and their effects on marine food webs. The review highlights the urgent need for further research into the behavior and fate of nanoplastics, which are the degradation product of microplastics, owing to their nano size they pose additional risks, unique properties, and potential for widespread ecological impacts. Studies have demonstrated that smaller microplastics and nanoplastics, particularly nanoplastics, are more toxic than larger microplastics. Additionally, microplastics and nanoplastics serve as vectors for contaminants such as heavy metals, exacerbating their toxicity. They also translocate through marine food chains, posing potential health risks. While evidence of their impact continues to grow, the chronic toxicity of microplastics and nanoplastics remains poorly understood, emphasizing the need for further research, particularly at the cellular level, to fully understand their effects on marine ecosystems and human health. This review also concludes with a call for standardized measurement methods, effective mitigation strategies, and enhanced international cooperation to combat this escalating threat. Future research should prioritize the complex interactions between microplastics and nanoplastics, other pollutants, and marine ecosystems, with the ultimate goal of developing holistic approaches to manage and mitigate the impact of plastic pollution. PRACTITIONER POINTS: Microplastic/nanoplastic translocate through marine food webs, affecting species and human health. Nanoplastics are more toxic than microplastics, exacerbating environmental risks. Nanoplastic aggregation influences their distribution and ecological interactions. Future research should focus on nanoplastic behavior, transport, and toxicity.

Disentangling the retention preferences of estuarine suspended particulate matter for diverse microplastic types

As a major source of microplastics (MPs) for global oceans, estuarine MPs pose challenges for numerical modeling due to their particle diversity, while hydrodynamics and suspended particulate matter (SPM) further exacerbate transport prediction uncertainties. This study employs a categorization framework to pinpoint 16 representative MPs types, precisely simulating their transport processes in the Yangtze River estuary (YRE). Furthermore, spatial links between SPM concentrations and MP types at 1800+ simulated sites were examined using ArcGIS and bivariate Local Indicators of Spatial Association (BI-LISA). Results indicate that low-density (≤0.95 g/cm³), small-diameter (<500 μm) fiber MPs are more prone to hetero-aggregation with estuarine SPM flocs, while MPs with opposite characteristics may move depending on their intrinsic properties. High-high BI-LISA clusters were observed both in river branches and at the confluence with the sea, the latter closely associated with the turbidity maximum zone that promote MP hetero-aggregation. The interaction of these currents and Yangtze (Changjiang) diluted water forms MPs clusters between 122.0°E and 122.5°E at the confluence of the South Branch, averaging over 870 μg/m3. Examining the trapping preferences of estuarine SPMs for various MPs through this classification framework can help to determine the bioavailability of environmental MPs to aquatic organisms and map the MPs baseline values for health risk quantification.

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

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

Microplastic pollution in the marine environment: Distribution factors and mitigation strategies in different oceans

As the COVID-19 pandemic began in 2020, plastic usage spiked, and microplastic (MP) generation has increased dramatically. It is documented that MP can transfer from the source to the ocean environment where they accumulate as the destination. Therefore, it is essential to understand their transferring pathways and effective environmental factors to determine the distribution of MPs in the marine environment. This article reviews the environmental factors that affect MP distribution in the oceans including abiotic such as ocean currents and wind direction, physical/chemical and biological reactions of MPs, natural sinking, particle size and settling velocity, and biotic including biofouling, and incorporation in fecal material. It was found that velocity and physical shearing are the most important parameters for MP accumulation in the deep ocean. Besides, this review proposes different research-based, national-level, and global-level strategies for the mitigation of MPs after the pandemic. Based on the findings, the level of MP pollution in the oceans is directly correlated to coastal areas with high populations, particularly in African and Asian countries. Future studies should focus on establishing predictive models based on the movement and distribution of MPs to mitigate the levels of pollution.

Environmental impact of microplastics and potential health hazards

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

Vitamin E Mitigates Polystyrene-Nanoplastic-Induced Visual Dysfunction in Zebrafish Larvae

Vitamin E (VitE), a potent antioxidant, has demonstrated significant potential in mitigating oxidative stress and cellular damage, making it a valuable agent for countering environmental toxicities, including those caused by polystyrene nanoplastics (PSNPs). This study examined the effects of PSNPs on the zebrafish visual system and evaluated the protective role of VitE. Zebrafish embryos were exposed to PSNPs (0.01, 0.1, 1, and 10 μg/mL) with or without 20 μM VitE co-treatment from fertilization to 6 days post-fertilization (dpf). Visual function, morphology, and molecular responses were assessed at 4 or 6 dpf. Exposure to PSNPs at concentrations of 0.1 to 10 μg/mL significantly increased bioaccumulation in the zebrafish eye in a concentration-dependent manner and disrupted the visual system. These disruptions caused a reduction in the eye-to-body length ratio and decreased optomotor response positivity and swimming distance, indicating impaired visual function and behavior. Furthermore, PSNPs elevated reactive oxygen species (ROS) levels, induced retinal apoptosis, and disrupted gene expression related to visual development (six6, pax2, pax6a, and pax6b), apoptosis (tp53, casp3, bax, and bcl2a), and antioxidant defense (sod1, cat, and gpx1a). VitE co-treatment significantly mitigated these adverse effects, reducing oxidative damage, restoring antioxidant defenses, and preserving retinal function. This study highlights the potential of VitE as a protective agent against PSNP-induced visual dysfunction and underlines the urgent need to address nanoplastic pollution to protect aquatic ecosystems.

Impact of microplastics on the human digestive system: From basic to clinical

As a new type of pollutant, the harm caused by microplastics (MPs) to organisms has been the research focus. Recently, the proportion of MPs ingested through the digestive tract has gradually increased with the popularity of fast-food products, such as takeout. The damage to the digestive system has attracted increasing attention. We reviewed the literature regarding toxicity of MPs and observed that they have different effects on multiple organs of the digestive system. The mechanism may be related to the toxic effects of MPs themselves, interactions with various substances in the biological body, and participation in various signaling pathways to induce adverse reactions as a carrier of toxins to increase the time and amount of body absorption. Based on the toxicity mechanism of MPs, we propose specific suggestions to provide a theoretical reference for the government and relevant departments.

Natural Organic Matter Stabilizes Pristine Nanoplastics but Destabilizes Photochemical Weathered Nanoplastics in Monovalent Electrolyte Solutions

Photochemical weathering and eco-corona formation through natural organic matter (NOM) adsorption play vital roles in the aggregation tendencies of nanoplastics (NPs) in aquatic environments. However, it remains unclear how photochemical weathering alters the adsorption patterns of NOM and the conformation of the eco-corona, subsequently affecting the aggregation tendencies of NPs. This study examined the effect of Suwannee River NOM adsorption on the aggregation kinetics of pristine and photoaged polystyrene (PS) NPs in monovalent electrolyte solutions. The results showed that photochemical weathering influenced the conformation of the eco-corona, which, in turn, determined NP stability in the presence of NOM. Hydrophobic components of NOM predominantly bound to pristine NPs through hydrophobic and π-π interactions, and extended hydrophilic segments in water hindered NP aggregation via steric repulsion. Conversely, hydrogen bonding facilitated the binding of these hydrophilic segments to multiple photoaged NPs, thereby destabilizing them through polymer bridging. Additionally, the stabilization and destabilization capacities of NOM increased with its concentration and molecular weight. These findings shed light on the destabilizing role of NOM in weathered NPs, offering new perspectives on environmental colloidal chemistry and the fate of NPs in complex aquatic environments.

Enhanced bioaccumulation and toxicity of Fenpropathrin by polystyrene nano(micro)plastics in the model insect, silkworm (Bombyx mori)

BACKGROUND

Nano(micro)plastics (NMPs) and agrochemicals are ubiquitous pollutants. The small size and physicochemical properties of NMPs make them potential carriers for pollutants, affecting their bioavailability and impact on living organisms. However, little is known about their interactions in terrestrial ecosystems. This study investigates the adsorption of Fenpropathrin (FPP) onto two different sizes of polystyrene NMPs and examines their impacts on an insect model, silkworm Bombyx mori. We analyzed the systemic effects of acute exposure to NMPs and FPP, individually and combined, at organismal, tissue, cellular, and gut microbiome levels.

RESULTS

Our results showed that NMPs can adsorb FPP, with smaller particles having higher adsorption capacity, leading to size-dependent increases in the bioaccumulation and toxicity of FPP. These effects led to higher mortality, reduced body weight, delayed development, and decreased cocoon production in silkworms. Additionally, the pollutants caused physical and oxidative damage to the midgut and altered gene expression related to juvenile hormone (JH) and silk protein synthesis. The gut microbiome analysis revealed significant changes and reduced abundance of potentially beneficial bacteria. Thus, the aggravated toxicity induced by NMPs was size-dependent, with smaller particles (NPs) having a greater impact.

CONCLUSIONS

This study demonstrates the role of NMPs as carriers for contaminants, increasing their bioavailability and toxicity in terrestrial ecosystems. These findings have significant implications for ecosystem health and biodiversity.

Polymer Biodegradation in Aquatic Environments: A Machine Learning Model Informed by Meta-Analysis of Structure-Biodegradation Relationships

Polymers are widely produced and contribute significantly to environmental pollution due to their low recycling rates and persistence in natural environments. Biodegradable polymers, while promising for reducing environmental impact, account for less than 2% of total polymer production. To expand the availability of biodegradable polymers, research has explored structure-biodegradability relationships, yet most studies focus on specific polymers, necessitating further exploration across diverse polymers. This study addresses this gap by curating an extensive aerobic biodegradation data set of 74 polymers and 1779 data points drawn from both published literature and 28 sets of original experiments. We then conducted a meta-analysis to evaluate the effects of experimental conditions, polymer structure, and the combined impact of polymer structure and properties on biodegradation. Next, we developed a machine learning model to predict polymer biodegradation in aquatic environments. The model achieved an Rtest2 score of 0.66 using Morgan fingerprints, detailed experimental conditions, and thermal decomposition temperature (Td) as the input descriptors. The model's robustness was supported by a feature importance analysis, revealing that substructure R-O-R in polyethers and polysaccharides positively influenced biodegradation, while molecular weight, Td, substructure -OC(═O)- in polyesters and polyalkylene carbonates, side chains, and aromatic rings negatively impacted it. Additionally, validation against the meta-analysis findings confirmed that predictions for unseen test sets aligned with established empirical biodegradation knowledge. This study not only expands our understanding across diverse polymers but also offers a valuable tool for designing environmentally friendly polymers.

An assessment of physiological and health responses in Catla catla fingerlings after polystyrene microplastic exposure

Microplastics (MPs) form when plastic debris is released into the aquatic environment, where they decompose and have deleterious effects on aquatic life. This study aimed to examine the harmful impacts of polystyrene MPs (PS-MPs) on the growth, carcass composition, hematology, digestibility, histopathology, and mineral analysis of Catla catla (11.09 ± 0.09 g/fish). Six experimental diets were prepared using canola meal (CM) as the base, each containing varying levels of PS-MPs: a control diet without MPs, and diets with 0.5%, 1%, 1.5%, 2%, and 2.5% PS-MPs. For ninety days, three groups of 15 fingerlings each were fed the test diets at a rate of 5% of their live, wet body weight. The growth rate and feed intake of C. catla fish showed a significant decline after the exposure to the diet containing 2.5% PS-MPs. Dietary inclusion of 2.5% PS-MPs resulted in reduced weight gain (g) and increased FCR. Mineral content and nutritional digestibility declined as PS-MP levels rose. PS-MPs led to a decrease in ash and protein content, while causing an increase in moisture levels and body fat. Moreover, exposure to PS-MPs resulted in significant reduction in RBCs, PLT, Hb, PCV, and MCHC, while WBCs, MCH, and MCV showed substantial increases. The histological analysis of the gut revealed elevated intestinal irregularities at 2.5% PS-MPs level. Notably, the present study revealed that PS-MPs accumulate in the gut, compromising the nutritional quality and overall well-being of C. catla fingerlings.

Spatiotemporal dynamics and tidal transport of microplastics in the tropical waters of the Gulf of Thailand

Microplastics (MPs) contamination was investigated along a freshwater-seawater continuum from Chumphon River to the Gulf of Thailand. The vertical distribution in the water column and contamination in green mussels were also studied. MPs were detected in all water samples and sediment samples. Furthermore, MPs were detected in 75% of the green mussels. A higher abundance of MPs was observed in the river system than in the coastal region, indicating that river runoff associated with inland human activities is the major sources of MPs in the coastal regions and cultured green mussels. In the water column, a polymer gradient varying with depth existed where low-density particles decreased from surface to subsurface and sediment while high-density particles exhibited the opposite pattern. Polymers in surface and subsurface water were predominantly composed of low-density polyethylene, polypropylene, and polystyrene particles. However, sediment samples were equally dominated by those mentioned low-density polymers and high-density polyethylene terephthalate, polyamide, rayon, and cotton particles. Furthermore, fibers were the most common shape found in water, sediment, and mussel samples representing 95% of all particles in river water samples and were evenly distributed throughout the water column regardless of density. However, only shorter fiber (mostly <1 mm) was detected in green mussel samples similar to their living environment. Blue, black and white particles dominated all samples. During the tidal cycle, half of the MPs entering the Gulf of Thailand returned to the river during high tide. This backflow predominantly comprised small fibers and low-density polymer MPs. The average daily load of MPs from Chumphon River to the Gulf of Thailand was 3.33 × 102 million items/day.

Exploring Nanoplastics Bioaccumulation in Freshwater Organisms: A Study Using Gold-Doped Polymeric Nanoparticles

The evaluation of nanoplastics bioaccumulation in living organisms is still considered an emerging challenge, especially as global plastic production continues to grow, posing a significant threat to humans, animals, and the environment. The goal of this work is to advance the development of standardized methods for reliable biomonitoring in the future. It is crucial to employ sensitive techniques that can detect and measure nanoplastics effectively, while ensuring minimal impact on the environment. To understand nanoplastics retention by freshwater organisms, phyto- and zooplankton, and mussels were exposed to gold-doped polymeric nanoparticles synthesized in our laboratory. The results demonstrated that measuring gold content using inductively coupled plasma mass spectrometry (ICP-MS), along with confirmation of its presence through electron microscopy in selected exposed samples provides insight into the accumulation and release of nanoplastics by organisms playing a relevant ecological role at the early levels of aquatic food webs.

Microplastics in soils: A comprehensive review

Microplastics (MPs) have become pervasive pollutants in terrestrial ecosystems, raising significant ecological risks and human health concerns. Despite growing attention, a comprehensive understanding of their quantification, sources, emissions, transport, degradation, and accumulation in soils remains incomplete. This review synthesizes the current knowledge on the anthropogenic activities contributing to soil MP contamination, both intentional and unintentional behaviors, spanning sectors including agriculture, domestic activities, transportation, construction, and industry. Furthermore, it examines the spatial distribution, accumulation, and abundance of MPs across various land use types, alongside a critical assessment of existing quantification methodologies. While the predominant metric for MP quantification is particle number concentration, integrating mass and area concentration enhances the ability to compare pollution levels, assess fluxes, and conduct risk analyses. Additionally, the review explores the transport behavior of MPs in soil, distinguishing between external mechanisms (abiotic factors: wind, leaching, and runoff, biotic factors: soil bioturbation and food chain interactions), and internal mechanisms that are impacted by the characteristics of MPs themselves (e.g., shape, color, size, density, surface properties), soil properties (e.g., porosity, pH, ionic strength, organic matter and mineral content), coexisting substances, and soil structural dynamics. The study of MP transport in soil remains in its early stages, with substantial gaps in knowledge. Future research should focus on integrating number, mass concentration, and area concentration for the more holistic quantification of MP abundance, and prioritize the development of more accurate and efficient methodologies. In addition, the investigation of MP transport and degradation processes under varying environmental conditions and soil management practices is critical for addressing this emerging environmental challenge.

Unveiling the crucial role of iron oxide transformation in simultaneous immobilization of nanoplastics and organic matter

Nanoplastics (NPs) have been found in natural environments. However, the sequestration of NPs and natural organic matter (NOM) coupled with the Fe(III) hydrolysis and subsequent iron oxides transformation remains unclear. Here, we investigated the behaviors of NPs during the dynamic transformation process of iron oxides in the presence of humic acids (HA). The quantification results of europium chelate-labeled polystyrene (PS) NPs and HA indicate that 87.60 % of NPs and 49.45 % of HA were sequestered in the precipitate by the end of the transformation (240 h). High-angle annular dark-field-scanning transmission electron microscopy-energy dispersive X-ray spectroscopy (HAADF-STEM-EDS) images show that NPs were doped into iron oxides during the recrystallization of ferrihydrite aggregates, while HA were adsorbed or penetrated into the nanoscale pores on the mineral surfaces, suggesting the formation of a stable iron oxides-NPs-NOM ternary nanocomplex with a core-shell structure. Fourier transform infrared spectrometer (FTIR) and two-dimensional correlation spectroscopy (2D-COS) analysis indicate that functional groups of iron oxides and HA, including hydroxyl, carboxyl, and FeO bonds, played a role in the binding process. In the presence of HA, the stability of the coprecipitation system was enhanced due to the increased electrostatic repulsion, which facilitated the full incorporation of NPs with iron oxides. These findings provide a new insight into the simultaneous immobilization of NPs and NOM.

Modeling of heteroaggregation driven buoyant microplastic settling: Interaction with multiple clay particles

The ecological risk of microplastics (MPs) has received widespread attention, but understanding ecological risk starts with understanding environmental migration. Heteroaggregation is an important process that affects the vertical migration of MPs, and the mathematical model is a common tool used to project the migration behavior of MPs. However, the mathematical model based on the aggregation of MPs with one clay particle is not applicable to simulate the migration behavior of buoyant microplastic (BMP). Hence, this study developed a model for heteroaggregation of one BMP with multiple clay particles based on the Population Balance Equation, and the main factors affecting the sedimentation of BMP are clarified through parameter sensitivity analysis and scenario simulation. The results show that neglecting the interaction of one BMP with multiple clay particles in the mathematical model can underestimate the predicted settling concentration of BMP, especially in aqueous environments with higher clay concentration and salinity. The settling process of BMP is controlled by the heteroaggregation rate, which is sensitive to environmental conditions and insensitive to particle properties. This study emphasizes the importance of considering the interaction of one BMP with multiple clay particles in the future mathematical model, which will provide a more reliable prediction of the migration of MPs in aquatic environments.

Distinctive toxic repercussions of polystyrene nano plastic towards aquatic non target species Nitrobacter vulgaris, Scenedesmus sp and Daphnia magna

The widespread application of plastics and its eventual degradation to micro-sized or nano-sized plastics has led to several environmental concerns. Moreover, nanoplastics can easily cascade through the food chain accumulating in the aquatic organisms. Thus, our study focussed on investigating the hazardous impact of nano-sized plastics on aquatic species including Nitrobacter vulgaris, Scenedesmus sp, and Daphnia magna. Various concentrations of polystyrene nanoplastics ranging from 0.01 mg/L to 100 mg/L were tested against Nitrobacter vulgaris, Scenedesmus sp, and Daphnia magna. The minimum inhibitory concentration of polystyrene nanoplastics in Nitrobacter vulgaris was found to be 25 mg/L, and in Daphnia magna, the median lethal concentration 50 was observed to be 64.02 mg/L. Exposure of Scenedesmus sp with increasing nanoplastic concentrations showed a significant decrease in total protein (p < 0.001), and chlorophyll content (p < 0.01), whereas the lipid peroxidation increased (p < 0.001) significantly. Similarly, Nitrobacter vulgaris and Daphnia magna showed a significant decrease in catalase activity (p < 0.001) and an increase in lipid peroxidation levels (p < 0.01). Concomitant with lipid peroxidation results, decreased superoxide dismutase levels (p < 0.01) and protein concentrations (p < 0.01) were observed in Daphnia magna. Besides, the increasing concentration of polystyrene nanoplastics displayed an elevated mortality rate in Scenedesmus sp (p < 0.001) and Nitrobacter vulgaris (p < 0.01). Further, scanning electron microscopy analysis substantiated the morphological alterations in Nitrobacter vulgaris and Scenedesmus sp on exposure to polystyrene nanoplastics.

Rainfall-induced microplastic fate and transport in unsaturated Dutch soils

Microplastic pollution has become a growing concern in terrestrial ecosystems, with significant implications for environmental and human health. Understanding the fate and transport of microplastics in soil environment is crucial for effective mitigation strategies. This study investigates the dynamics of microplastic (Low-density polyethylene (LDPE), polybutylene adipate terephthalate (PBAT), and starch-based biodegradable plastic) transport in unsaturated soils under varying rainfall intensities and soil types, aiming to elucidate the factors influencing their behavior. Effluent samples were analyzed to measure microplastic transport, with microplastic balance analysis ensuring experimental accuracy. The setup replicated real-world flow conditions, providing insights into microplastic transport in unsaturated porous media. Microplastic balance analysis revealed high recovery factors (between 64 % and 104 %), indicating the reliability of the experimental approach. Microplastic transport varied significantly between sandy loam and loamy sand soils, with loamy sand soils exhibiting higher wash-off rates due to their unique properties. LDPE microplastics showed a higher tendency to detach from soil columns compared to PBAT and starch-based particles. Higher rainfall intensity in loamy sand soil columns resulted in an increased washout of LDPE, PBAT, and starch-based particles by 92 %, 144 %, and 85 %, respectively, compared to low rainfall intensity. In sandy loam soil, increased rainfall intensity resulted in a significantly higher washout of LDPE, PBAT, and starch-based particles with percentages of 93 %, 69 %, and 45 %, respectively. This underscores the important role of water flow in mobilizing microplastics within the soil matrix.

Microplastics in freshwater ecosystems: probabilistic environmental risk assessment and current knowledge in occurrence and ecotoxicological studies

Ecotoxicological studies involving microplastics (MPs) conducted on a laboratory scale may not always accurately mirror real environmental conditions (types, sizes, shapes, and concentrations of MPs). This review primarily focused on examining studies that investigated the prevalence of MPs in freshwater environments and accumulation in organisms worldwide, considering important factors such as morphology, particle size, and the specific polymer types involved. This review also encompassed ecotoxicological studies related to MPs, and ecological risk analyses were carried out based on the obtained ecotoxicological data. Based on the extensive dataset collected, we determined the hazardous concentration for 5% of the tested organisms (HC5) and estimated for the first time a predicted noneffect concentration (PNEC) value for two distinct types of MPs polymers: polystyrene (PS) and polyethylene (PE), based on the species sensitive distribution (SSD) curves obtained from nonobserved concentration (NOEC) values, with 0.003 mg L-1 for PS and 0.011 mg L-1 for PE. Furthermore, another PNEC value for 7 types of MPs (PE, PS, polyvinyl chloride, PA6, polyester, polyethylene terephthalate, and ethylene acrylic acid copolymer (EEA copolymer)) was calculated (0.0027 mg L-1 or 2.61 particles L-1). Subsequently, the risk quotient (RQ) was computed utilizing data obtained from the measured environmental concentrations of 18 places. An RQ value of 0.094 was obtained, inferring that MPs have a low-risk potential globally. However, when the RQ values were examined for each country separately, they exhibited significant variability (RQ = 22.06 in Malaysia and 0.000008 in Australia). Overall, this review provides a comprehensive overview of the current knowledge on MP abundance in freshwater environments, the associated ecotoxicological research to reinforce the outcomes derived from the risk analysis, and their accumulation in biota.

Micro-nanoscale polystyrene co-exposure impacts the uptake and translocation of arsenic and boscalid by lettuce (Lactuca sativa)

The influence of micro-nanoplastics (MNPs) on the fate and effects of other pollutants present in the environment is largely unknown. This study evaluated if the root exposure to MNPs (polystyrene, PS; 20 or 1000 nm) had an impact on the accumulation of arsenic and boscalid (As and Bos) in lettuce (Lactuca sativa). Under hydroponic conditions, plants were co-exposed to MNPs at 10 or 50 mg/L, and to 1 mg/L of each environmental pollutant (EP). For soil-like media, plants were exposed to MNPs at 50 and EPs at 10 mg/kg. Phytotoxicity was enhanced by PS under both growth conditions, particularly by nanoscale PS (nPS), although impacts were less in potting mix-grown plants. Nanoscale PS had a greater impact than microscale PS (μPS) on As fate; the As translocation factor from roots to the edible shoots was increased 3-fold in plants exposed to nPS (50 mg/L) and EPs. PS dose and size had a variable impact on Bos uptake and translocation. Fluorescent microscopy analysis of lettuce co-exposed to MNPs and EPs suggests that nPS is entering the roots and translocating to the leaves, while μPS mostly remains in the roots. Pyrolysis-GC/MS showed that in solid media, the presence of EPs significantly increased the translocation of nPS to lettuce shoots from 4.43 ± 0.53 to 46.6 ± 9.7 mg/kg, while the concentration of μPS in the shoots remained the same regardless of the presence of EPs (ranging between 13.2 ± 5.5 to 14.2 ± 4.1 mg/kg). These findings demonstrate that co-exposure of MNPs with other EPs can significantly impact co-contaminant accumulation and toxicity, presenting an unknown risk to humans and other receptors.

Effects of microplastics and salt single or combined stresses on growth and physiological responses of maize seedlings

Plastic film (mulch film) is widely used in saline and alkaline soils because it can effectively reduce salt stress damage. However, it results in the accumulation of microplastics (MPs) in the soil, which pose a threat to crop growth and production. This study investigates the effects of 50 mg l-1 MPs and 100 mM sodium chloride (NaCl), individually or in combination, on the growth and physiological characteristics of maize (Zea mays) seedlings. The results demonstrated that compared to the control, MPs and NaCl single or combined stress reduced seedling biomass and water content, and the combined stress was more serious. Stress significantly reduced N and K contents in leaves, and Na content under combined stress was lower than under single NaCl stress. Compared to single stress, the combined stress further enhanced oxidative damage by increasing H2O2 and MDA content, a disrupted chloroplast structure, and reduced chlorophyll content, ultimately leading to a decline in chlorophyll fluorescence parameters and photosynthetic efficiency. Single MPs or NaCl stress led to the accumulation of proline, soluble proteins, and soluble sugars, while the combined stresses further increased the content of these osmotic substances in plants. Moreover, single or combined stress increased the activity of CAT, POD, SOD and the content of AsA and GsH. Collectively, NaCl and MPs single or combined stress exert notable toxic effects on maize seedling growth. Although the combined stress inhibited seedling growth more than the single stress, the combined stress of MPs and NaCl showed antagonistic effects. These findings underscore the importance of assessing the ecological risks posed by the combined effects of MPs and salt stresses on maize plants.

A Critical Review of an Environmental Risk Substance Induced by Aging Microplastics: Insights into Environmentally Persistent Free Radicals

Microplastics (MPs), as an emerging contaminants category, can undergo complex aging in a variety of environmental matrices in which the chemical bonds of polymer molecules can be broken to form free radicals. While the existence of free radicals in aged plastics has been known for over half a century, only recently has significant research on a new type of environmentally risky substance, namely environmentally persistent free radicals (EPFRs), present in aged MPs and their environmental effects, been started, but it is still in its infancy. To address these issues, this work examines EPFR generation on MPs and their environmental effect by reviewing publications from 2012 to 2023. The aging processes and mechanisms of MPs in the environment are first summarized. Then, the occurrence and formation mechanisms of EPFRs on aged MPs are specifically discussed. Additionally, the reactivity of EPFRs on aging MPs and their influencing factors are comprehensively considered, such as their physicochemical properties, oxygen content, and coexisting substances. Due to their reactivity, EPFRs can interact directly with some substances (e.g., p-nitrophenol and proteins, etc.) or induce the generation of reactive oxygen species, leading to diverse environmental effects, including pollutant transformation, biotoxicity, and health risks. Finally, research challenges and perspectives for EPFRs formation on aging MPs and related environmental implications are presented. Given the environmental fate and risk of MPs-EPFRs, our urgent call for a better understanding of the potential hazards of aged MPs is to help develop a sustainable path for plastics management.

Optimising microplastic polyethylene terephthalate fibre extraction from sediments: Tailoring a density-separation procedure for enhanced recovery and reliability

Despite the presence of microplastics in sediments being widely acknowledged, the absence of standardised processing methods in extracting microplastics can compromise reliable and comparable results. Density separation is a predominant method for extracting microplastics from sediments. In this study, Sodium Polytungstate (ρ = 1.6 g cm-3) was selected as the density separation agent for three key factors: i) optimal density for extracting common plastic polymers, ii) low toxicity, and iii) recycling potential of the solution. It is therefore cost-effective, and the risk of solution dispersal is minimal. The solution was tested through four separation procedures, extracting PET fibres from three artificial sediment mixtures (i.e., pure sand, pure mud, and 50 % sand and 50 % mud). The results indicate that the solution employed in this work is highly effective for extracting microplastic fibres from sediments, with recovery rates up to 99 %. However, the results highlight differences in the recovery among the four procedures and in terms of the sediment characteristics. Specifically, extracting microplastics was easier in sandy sediment samples than in mud-rich ones. The complexity of extracting microplastics from mud-rich sediments results from i) the creation of microplastic-sediment aggregates forming denser structures, that settle down trapping microplastics in sediments; ii) the development of a clay sediment cap that hinders the rise of microplastics to the surface. Reducing the risk of underestimation of microplastic content in mud-rich samples can be accomplished by applying a procedure that involves placing the samples with the Sodium Polytungstate solution on a stirring plate while progressively lowering the rotation velocity. Using this method, cohesive sediments lose their ability to trap microplastics while aggregating, consequently reducing their ability to drag microplastics to the bottom. This facilitated microplastics to reach the liquid surface, thereby enabling an efficient retrieval even in mud-rich samples.

Predicted Potential for Aquatic Exposure Effects of Per- and Polyfluorinated Alkyl Substances (PFAS) in Pennsylvania's Statewide Network of Streams

Per- and polyfluoroalkyl substances (PFAS) are contaminants that can lead to adverse health effects in aquatic organisms, including reproductive toxicity and developmental abnormalities. To assess the ecological health risk of PFAS in Pennsylvania stream surface water, we conducted a comprehensive analysis that included both measured and predicted estimates. The potential combined exposure effects of 14 individual PFAS to aquatic biota were estimated using the sum of exposure-activity ratios (ΣEARs) in 280 streams. Additionally, machine learning techniques were utilized to predict potential PFAS exposure effects in unmonitored stream reaches, considering factors such as land use, climate, and geology. Leveraging a tailored convolutional neural network (CNN), a validation accuracy of 78% was achieved, directly outperforming traditional methods that were also used, such as logistic regression and gradient boosting (accuracies of ~65%). Feature importance analysis highlighted key variables that contributed to the CNN's predictive power. The most influential features highlighted the complex interplay of anthropogenic and environmental factors contributing to PFAS contamination in surface waters. Industrial and urban land cover, rainfall intensity, underlying geology, agricultural factors, and their interactions emerged as key determinants. These findings may help to inform biotic sampling strategies, water quality monitoring efforts, and policy decisions aimed to mitigate the ecological impacts of PFAS in surface waters.

Characterization of Mycelium Biocomposites under Simulated Weathering Conditions

Expanded polystyrene (EPS) remains a popular packaging material despite environmental concerns such as pollution, difficulty to recycle, and toxicity to wildlife. The goal of this study is to evaluate the potential of an ecofriendly alternative to traditional EPS composed of a mycelium biocomposite grown from agricultural waste. In this material, the mycelium spores are incorporated into cellulosic waste, resulting in a structurally sound biocomposite completely enveloped by mycelium fibers. One of the main criteria for shipping applications is the ability of a material to withstand extreme weather conditions. Accordingly, this study focused on evaluating a commercially available mycelium material before and after exposure to various weathering conditions, including high and low temperatures at different humidity levels. Fourier transform infrared spectroscopy (FTIR) was performed to examine any transformations in the mycelium structure and composition, whereas scanning electron microscopy (SEM) was used to reveal any changes in the morphology. Similarly, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) analyses were conducted to evaluate the thermal behavior, whereas mechanical properties were measured by using shore hardness and Izod Impact testing. Although some irreversible changes were observed due to the exposure to high temperatures, the material exhibited good thermal stability and impact resistance. FTIR analysis demonstrated small changes in the biocomposite structure and protein rearrangement as a result of weathering, whereas SEM revealed some cracking in the cellulose substrate. A combination of low temperatures and humidity resulted in significant moisture absorption, as indicated by TGA and DSC. This in turn decreased the hardness of the fibers by nearly 2-fold; however, the impact strength of the entire biocomposite remained unchanged. Overall, these results provide important insight into the structure-property relationships of mycelium-based materials.