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

Microplastics removal from stormwater runoff by bioretention cells: A review

Microplastics (MPs), as a new category of environmental pollutant, have been the hotspot of eco-friendly issues nowadays. Studies based on the aging process, the migration pattern of MPs in runoff rainwater, and the use of bioretention cells to remove MPs from runoff rainwater are beginning to attract widespread attention. This review analyses the migration patterns of MPs in rainwater runoff through their sources, structure and characteristics. The mechanism of removing MPs from runoff stormwater, the purification efficiency of different fillers and their influencing factors, and the accumulation, fate, and aging of MPs in bioretention cells are described. Furthermore, the hazards of MP accumulation on the performance of bioretention cells are summarised. Future directions for removing MPs in bioretention cells are proposed: (1) research on MPs smaller than 100 µm; (2) influence of MPs aging process on bioretention cells; (3) exploration of more effective fillers to enhance their removal efficiency; (4) research on synergistic removal mechanism of MPs and other pollution.

Dynamic process of UV-aging polystyrene microplastics, simultaneous adsorption of drugs, and subsequently coagulative removal together

The aging of plastics and their adsorptive interactions with the residual contaminants in water has attracted increasing attentions. In this study, the dynamic process of UV-aging polystyrene (PS) microplastics (MPs) were semi-quantitatively analyzed using a coulter counter, and the adsorptive interactions between the aged PS MPs and two popular drugs[norfloxacin (NOR) and chloroquine phosphate (CQ)] were investigated simultaneously. The MPs presented a rapid size downtrend, reduced from micrometer to nanometer, and the particle number concentration increased about 2 -3 times after a 36.0 h aging effect. The apparent UV-aging process of PS MPs mainly obeyed the pseudo-first order kinetic model in currently measured MPs' size range. The drug uptakes of the aged MPs were fully consistent with the contents of oxygen-containing groups on MPs surface rather than MPs' size. The involved adsorption mechanisms were investigated in detail mainly including electrostatic attraction, hydrogen bonding, and π-π electron donor-acceptor interaction. The drug adsorbed MPs were subsequently efficiently removed by an enhanced coagulation together owing to the synergistic effects of the two pollutants. This study provides a novel and comprehensive perspective on the fundamental understanding the UV-aging process of MPs and the simultaneous adsorption behaviors, furthermore, a strategy was proposed for their collaborative removal.

Influence of landfill leachate microenvironment on the occurrence of microplastics: TOC changes are the main driving factor

Factors such as inorganic salts, heavy metals and organics in landfill leachate can affect the environmental behavior and transport properties of microplastics. However, the influence of the microenvironment on the behavioral effects of microplastics in landfill leachate is still limited. In this study, the abundance characteristics of microplastics in leachate from 15 landfills in the North China Plain were investigated. The results showed that the abundance of microplastics in the leachate in this region was 712.0 items/L, which was mainly composed of small particle size and long fibrous microplastics. The relationships between leachate physicochemical factors and microplastic accumulation patterns were explored using models such as structural equations. Among them, TOC (Total Organic Carbon) had the strongest driving effect on 50-100 μm microplastics. And it had different effects on different microplastics: it promoted the degradation of PET (Polyethylene terephthalate), while it inhibited the degradation of PVC (Polyvinyl chloride), FVMQ (Fluorosilicone rubber) and PSU (Polysulfone). The ridge regression model indicated that the interaction of landfill age with Cr (Chromium) and the interaction of redox potential with Cr were the key factors influencing the behavioral characteristics of microplastics in leachate. These results provide a scientific basis for the treating waste leachate and the controlling the emerging pollutants.

Deciphering the source contribution of microplastics in the glaciers of the North-Western Himalayas

Microplastics (MPs) and nanoplastics (NPs) have been largely studied in marine environments, but there lies a significant gap in assessing their occurrence and impacts in glacier environments. This study investigates the occurrence and pollution risks of MPs and NPs in glaciers, suspended air, and dry deposition across the northwestern Himalayas. MPs concentration ranged from 1000 particles m-3 in Kolahai glacier to 151000 particles m-3 in Thajwas glacier. In suspended air, MPs occurred at 5 particles m-3, while dry deposition samples showed a concentration ranging from 1 to 13 particles m-2 d-1. Dynamic light scattering (DLS) confirmed the presence of NPs in all glaciers, with sizes varying between 31 and 689 nm in Thajwas glacier and 360-953 nm in Harmukh glacier. HYSPLIT modelling revealed that air masses reaching Himalayan glaciers predominantly originate from global sources (75 %). The pollution load index (PLI) ranged from 3.9 (hazard category I) to 40 (hazard category IV), indicating moderate to excessive pollution of glaciers. While as polymer hazard index (PHI) ranged from 10 (hazard category II) to 1987 (hazard category V), indicating medium to extreme danger due to presence of polyvinyl chloride (PVC) and polyacrylonitrile (PAN). The presence of MPs and NPs accelerate glacier melting due to their light absorbing properties highlighting need for further studies.

Aging properties of polymer pellets, release of secondary microplastics and additives in the water environment under laboratory-controlled conditions

In this work, the long-term degradation of polymer pellets (also known as the primary microplastics/MPs) was monitored under laboratory-controlled conditions. Polymers of different origin such as the ABS, HDPE and PA (non-processed, recycled) were exposed to demineralized and artificial seawater, stored in room (20-24 °C) and cold (4-8 °C) temperatures during 20 months period. Surface topography and thermal characteristics of selected primary MPs were examined with the use of digital microscope and thermogravimetric (TGA) analysis. Release of secondary MPs into the water solutions was monitored with digital microscopy observations and µ-FTIR analyses. Additionally, leaching of the additives/plasticizers was studied by the GC-MS technique. Periodical, microscopic observations of the surface topography of single pellets show that some polymers undergo deformation over time in the water environment. According to results of the surface roughness, the external structure of the primary MPs (e.g. HDPE and PA) deteriorate after 6 months of exposure to water and cold temperatures. As indicated by the TGA analysis the water penetrates the polymer-matrix (HDPE), changing its physicochemical properties. The µFTIR analyses confirm that primary MPs fragment into smaller particles (secondary MPs), while exposed to various degradation factors (e.g. temperature, pH and salinity changes). The average size of all identified secondary MPs ranges between 13 and 1055 µm. The MP-like particles in the size range of ∼3-230 µm have been identified by the microscopic analyses. While exposing the primary MPs to different degradation factors for 20 months, no significant concentrations of phthalates were released into the water solutions.

Decreased particle size enhances the aging behavior of microplastics during sewage sludge composting: Physicochemical properties and cadmium loading

Although aerobic composting is capable of aging microplastics (MPs), the influence of size on MPs aging during composting and loading of cadmium (Cd) remains unclear. Therefore, we investigated variations in the physicochemical properties of polyethylene terephthalate microplastics (PET-MPs) with different sizes (1.0 -5.0, 0.2 -1.0, and 0.05 -0.2 mm) during composting and the concentration of Cd accumulated on the surface of different-sized aged PET-MPs. The results indicated that PET-MPs exhibited size-dependent as they aged during composting, with smaller sizes aging faster. After composting, the 0.05 -0.2 mm PET-MPs had the greatest increase in specific surface area (205.5 %), compared with the 1.0 -5.0 mm (18.7 %) and 0.2 -1.0 mm (95.6 %) PET-MPs. The greatest increase in the carbonyl index/oxygen-to-carbon atom ratio was also observed for the 0.05 -0.2 mm PET-MPs, which were 2.25 / 3.27 and 0.02 / 2.11 times higher than those of the 1.0 -5.0 mm and 0.2-1.0 mm PET-MPs, respectively. Similarly, size-dependent accumulation of Cd on the aged PET-MPs was also observed: 0.05-0.2 mm (5.37 mg/kg Cd) > 0.2 -1.0 mm (2.90 mg/kg Cd) > 1.0-5.0 mm (0.78 mg/kg Cd). These findings demonstrate that the aging behavior of polymer is closely related to their size, emphasizing the role of size in the fate and pollutant loading of polymer.

Nanoplastics enhance tebuconazole toxicity in lettuce by promoting its accumulation and disrupting phenylalanine metabolism: Importance of Trojan horse effect

Nanoplastics (NPs) are ubiquitous in agricultural environments and may exacerbate environmental risks of pesticides. This study investigates how NPs influence the toxicity of tebuconazole in lettuce. In a hydroponic model, NPs (10 and 50 mg/L) enhanced tebuconazole accumulation in roots and exacerbated its toxicity. To elucidate the underlying mechanisms, a combination of in vivo, in vitro, and in silico models was employed. The results indicated that NPs were taken up by roots through apoplast pathway, predominantly accumulating in roots (35.6-40.7 %) due to aggregation in root sap and adhesion to cell wall. Tebuconazole adsorbs onto NPs with a high adsorption capacity (123.7 mg/g), enabling NPs to serve as carriers that facilitate tebuconazole entry into roots. Once in the root sap, tebuconazole desorbed from NPs and accumulated in cell walls, leading to higher residue in the roots (7.19-9.85 mg/kg). Furthermore, tebuconazole bound to key proteins involved in auxin biosynthesis (e.g., YUC) and signaling (e.g., TIR), thereby inhibiting tryptophan-dependent auxin biosynthesis pathway and disrupting TIR1/AFB-mediated auxin signaling. Additionally, tebuconazole suppressed the phenylalanine pathway, reducing antioxidant secondary metabolites such as flavonols. When NPs are present, co-exposure intensified the inhibition of auxin and phenylalanine pathways, thereby amplifying the toxicity of tebuconazole, as evidenced by impaired plant phenotypes (e.g., biomass, root tips) and disrupted antioxidant systems. This study reveals threats posed by NPs and tebuconazole in agricultural systems and highlights the novel carrier effect of NPs in enhancing tebuconazole toxicity, emphasizing the urgent need to assess the fate and toxicity of NPs and coexisting pollutants.

Biodegradation of polystyrene and its mechanisms driven by a customized lignin-degrading microbial consortium and degrading bacteria

Polystyrene (PS), being resistant to biodegradation, poses a significant environmental challenge. This study isolated highly effective lignin-degrading microbial consortia from samples collected at six sites rich in lignin-degrading bacteria. After 360 days of enrichment, a stable lignin-degrading microbial consortium, LQX-03, was successfully established. LQX-03 demonstrated notable degradation efficiency not only for lignin (21-day degradation rate of 54.6 %) but also for PS (21-day degradation rate of 13.1 %). Importantly, PS-induced LQX-03 communities overlapped with the original lignin communities in 13 genera, revealing a close relationship between the degrading microbial compositions of the two substrates.Additionally, Pseudomonas putida Q1, isolated from LQX-03, exhibited significant capability in simultaneously degrading lignin and PS, achieving degradation rates of 36.1 % and 4.4 %, respectively. The strain was also able to alter the functional groups of PS, increasing its hydrophilicity. Gene and enzyme expression analyses revealed that key lignin-degrading enzymes, such as laccase (CopA) and DyP peroxidase, were significantly upregulated when PS was the sole substrate. Laccase CopA expression increased by 1.76-fold and 1.41-fold, while DyP expression increased by 1.24-fold. These results indicate that these enzymes likely play a crucial role in PS depolymerization and biodegradation. Further molecular docking analysis confirmed that laccase CopA could bind to PS. In summary, this study provides preliminary insights into the potential links between lignin-degrading and plastic-degrading microorganisms and their enzymes. It suggests that the biodegradation of synthetic plastics may rely on ancient natural lignin-degrading enzymes. These findings offer a new perspective and valuable data for developing efficient plastic biodegradation strategies.

Adsorption behavior of crude oil hydrocarbons on polyethylene microplastics in batch experiments

This study examines the impact of microplastics on the fate of spilled crude oil in water. Batch adsorption experiments were conducted using polyethylene microplastics ranging in size between 300 and 600 μm. Environmentally relevant concentrations of crude oil and microplastics were tested. Samples processing involved liquid-liquid extraction (LLE) followed by quantitative analysis using Gas-Chromatography coupled to Mass Spectrometry. Kinetic analyses employed the most commonly used models in microplastic adsorption studies, including the pseudo-first order, pseudo second-order, Elovich, and intra-particle diffusion models. Results mainly conformed to the Elovich model, followed by the pseudo-second order model, suggesting chemisorption. Isotherm evaluations involved the Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich models, selected for their effectiveness in describing the behavior of microplastics in adsorption studies. These models revealed diverse behaviors: alkanes from nC11-nC21 conformed to the Freundlich isotherm, suggesting multilayer adsorption. While nC10, nC27-nC29, nC33, and nC34 were best described by the Langmuir model, and nC22-nC26 and nC30-nC32 adhered to the Temkin model, both indicative of monolayer adsorption. Notably, nC35 adsorption was best described by the Dubinin-Radushkevich model. The different PAHs exhibited preferences for either the Freundlich or the Langmuir model. The maximum adsorption capacities of the contaminants onto polyethylene were 263.12 and 101.57 mg.g-1 for the targeted alkanes and PAHs, respectively, corresponding to a maximum adsorption of 5.75 mg of targeted hydrocarbons per m2 of polyethylene. The study highlighted the potential role of microplastics in influencing the environmental fate of selected crude oil hydrocarbons and provided insights into their interaction and partitioning behavior in water.

Anthropogenic solid waste is ubiquitous in bird nests in coastal multiple use protected areas

Anthropogenic solid residues are a serious environmental issue, affecting both terrestrial and aquatic ecosystems. Birds are particularly vulnerable to waste exposure, as they can interact with it through ingestion, entanglement, or by incorporating residues into their nests. The present study aimed to investigate the occurrence of anthropogenic residues in bird nests and how socio-environmental parameters affect nest anthropogenic contamination within and outside coastal protected areas. The results showed a widespread occurrence of anthropogenic residues in nests of 10 out of 17 bird species studied. Specifically, in nests of Great Kiskadee Pitangus sulphuratus a high contamination frequency (95 %) was verified. In the Generalized Linear Model urbanization levels and vegetation cover assessed using Human Modification Metric (HMc) and the Normalized Difference Vegetation Index (NDVI) did not have statistically significant effects on the presence of anthropogenic residues in bird nests. Similarly, nest location (inside or outside protected areas boundaries) and substrate type (natural or artificial) were not related to contamination level. Therefore, our results suggest that anthropogenic residues are already ubiquitous even within less anthropized areas. Such findings underscore the urgent need for enhanced waste management strategies to mitigate the negative impacts of anthropogenic waste on wildlife and local ecosystems, particularly in protected areas.

Microplastics accumulate in all major organs of the mediterranean loggerhead sea turtle (Caretta caretta)

Microplastics (MPs) are a pervasive marine environmental pollutant, posing a serious threat to marine ecosystems and organisms at all trophic levels. Plastic ingestion is well documented in marine turtles, and loggerhead sea turtles (Caretta caretta) have been identified as an indicator species to monitor MP pollution globally. Our understanding of the translocation and bioaccumulation potential of MPs beyond the gastrointestinal tract is, however, limited. Here we demonstrate that MP translocation occurs in these marine reptiles and present a comprehensive analysis of MP accumulation in body tissues of 10 stranded Mediterranean loggerhead turtles including the kidney, liver, spleen, heart, skeletal muscle, subcutaneous fat, stomach, intestine, and reproductive organs. Foreign microparticles were identified in 98.8 % of all samples (∼70 % being MPs) and were significantly concentrated in the reproductive organs followed by the heart. Raman spectroscopy revealed that polypropylene, cotton fibres, and polyethylene were the most common microparticle types, and optical photothermal infrared (O-PTIR) spectroscopy provided direct visualisation of cotton microfibres embedded in loggerhead heart tissue. Future studies should determine the biological impact of MP bioaccumulation in sea turtle organs, to fully appreciate the impacts of these anthropogenic pollutants on protected and vulnerable populations worldwide.

Polypropylene microplastics reshape diazotrophic community composition and interactions in the plastisphere without affecting the rhizosphere of Capsicum annuum L

Interactions between microorganisms and microplastics play a crucial role in soil biological processes; however, the response of microbial functional groups in the presence of microplastics (MP) remains unclear. In this study, we investigated the diversity and composition of free-living nitrogen-fixing microorganisms (diazotrophs) in the rhizosphere and plastisphere of pepper (Capsicum annuum L.) across three growth stages under MP stress, using an optimized pipeline for functional nifH gene sequence analysis. Our results showed that MP addition suppressed plant growth, although soil properties were not significantly altered, except for soil pH, which was significantly reduced at each plant growth stage. Notable differences in diazotrophic community composition were observed between the rhizosphere and plastisphere, with the genus Rubrivax exhibiting a significantly lower relative abundance in the plastisphere. Moreover, we found strong deterministic assembly processes and intense network structures of diazotrophs in the plastisphere. Interestingly, MP addition did not significantly alter the diversity, composition, or network properties of diazotrophic communities in the rhizosphere compared to control soils. Our study provides insights into the interactions between microbial functional groups and microplastics, enhancing our understanding of the biological processes that drive ecological nutrient cycling and balance in changing environments.

The impact of polyvinyl chloride microplastics on carbon and nitrogen cycling in peat-forming environments: relevance of the filler additive calcium carbonate (CaCO3)

Peat-forming wetlands (PFW) are crucial in the global C-cycle, yet they are increasingly threatened by various anthropogenic pressures, including microplastic (MP) pollution. We investigate the impacts of polyvinyl chloride (PVC) and its additive, calcium carbonate (CaCO3) on organic matter (OM) degradation in PFW. We conducted two experiments: first, by mixing peat soil with increasing concentrations of crushed sanitary PVC-MP (0.3 %, 3 %, and 30 %) and second, by assessing the role of CaCO₃ in modulating these impacts. Our findings revealed significant alterations in peat chemical properties largely mediated by CaCO3 (i.e. increased pH, and Ca2+, Mg2+, K+ concentrations). PVC-MP increased carbon dioxide (CO2) and methane (CH4) production, as well as dissolved organic carbon release. CaCO3 may have enhanced CO2 release through its dissolution and contributed to CH4 production as a C source for a more diverse and active methanogenic community (higher mcrA gene abundance). Shifts in microbial community composition (e.g. reduction of Acidobacteriae and increase in active fermenters, such as Clostridia) and metabolism (higher lignin-like compounds degradation and P-uptake activity but lower activity of labile-C degrading enzymes) also contributed in the C-cycle alterations. PVC-MP enhanced denitrification (narG gene abundance) but reduced relative proportion of the ammonia-oxidizing archaea Nitrososphaeria, leading to inhibition of nitrification. The effects of PVC-MP were concentration-dependent, with CaCO₃ strongly influencing on the C cycle, while its impact on the N cycle was only partial, suggesting potential effect of other additives, such as plasticisers. Overall, our results highlight a significant disruption of microbial processes due to MP pollution, leading to increased greenhouse gas emissions and significant implications on the role of PFW as global C-sinks.

Innovative prototype for the mitigation of water pollution from microplastics to safeguard the environment and health

Microplastics (MPs) are ubiquitary environmental pollutants facilitated by anthropic activities as wastewaters (WWs) not properly treated or dispersed. Our study focused on the validation of an innovative prototype filter for its future applications in WWs Treatment Plants (WWTPs) to reduce the release of MPs in the environment. The aims of the study were: The WWTPs resulted in catching 85 % and 73 % of MPs >10 and MPs <10 μm, respectively; instead, the WWTPs-prototype treated outputs showed a further reduction of 99 % and 92 % of the uncaught MPs. The mussel haemolymphs analysis showed a decrease of 100 % and 95 %, respectively, for both MPs <10 and >10 μm in filtering treatment against the normal WWTPs outputs. We revealed longer LMS times in mussels exposed to prototype-filtered WWs (29-41 min) compared to the raw output of WWTPs (18-24 min). MF and q-PCR of all studied genes revealed a reduced genotoxicity in mussels exposed to prototype-treated WWs. Hence, the results demonstrated the prototype efficacy, and it will be tested in real WWTPs at a field scale in the next study.

Factors influencing the vertical distribution and transport of plastics in riverine environments: Theoretical background and implications for improved field study design

Rivers have been widely recognized as important conduits and accumulation sites for plastics. Accurately describing plastic fate and transport in these systems is essential for the development of numerical models, estimating loads to oceans, and implementing effective management strategies. However, plastic transport mechanisms within fluvial environments are not well understood, and field studies often do not provide sufficient information to test analytical models of transport. Sediment transport has dynamical similarities to plastics transport in water bodies, enough to warrant further investigation into how principles from sediment transport can be used to guide the study of plastics. In this review, we summarize fundamentals from sediment transport research and their application to plastics, then use these to make suggestions of clarifying research questions and riverine field study design with the goal of generating more insightful data that can be used to understand and predict plastic fate and transport. We focus specifically on factors influencing plastic vertical distribution and movement in the water column, as variations in this direction have historically been overlooked or oversimplified in rivers.

Enhanced remediation of petroleum in soil by petroleum-degrading bacterium strain TDYN1 and the effects of microplastics

Total petroleum hydrocarbons (TPH) are a kind of widely distributed pollutant, while its bioremediation in situ and how it is affected by microplastics (MPs) in soil remains unknown. A pot experiment was conducted to investigate the degradation capabilities of total petroleum hydrocarbons (TPH) by a novel petroleum hydrocarbon-degrading bacterium TDYN1 with different concentrations of microplastics PP and PE. The TDYN1 significantly enhanced TPH degradation rate at 42.4 ± 0.9%, compared to 12.1 ± 2.6% in the control. The microplastics affected the TPH degradation depended on their amount, and no difference in degradation rates between PP and PE. The 1% PP and PE facilitated the degradation of TPH, while the 4% PP and PE inhibited it after strain added. Strain TDYN1 increased the dehydrogenase, polyphenol oxidase and urease enzyme activities, and the number of TDYN1. After remediation, the pakchoi yield was increased by strain addition, but was reduced by PE, indicating a risk of TPH and PE combined pollution for vegetable growing. It helps to better understand the microbial remediation on TPH-microplastic compound-contaminated soil, and provide theoretical support for its evaluation of application.

Risk-based integrated framework for evaluating effects of microplastics to aquatic ecosystems and human health

The widespread presence of microplastics (MPs) in environments and the food web is a serious concern for both aquatic ecosystems and human health. Most studies have used single tool to assess risks primarily to organisms and humans, leaving gaps in comprehensive risk assessments. This study conducted an investigation of MP abundances in surface water and wild oysters from natural estuaries of major rivers in Taiwan. Additionally, the data also used to develop an integrated risk-based framework for evaluating potential risks from organisms to human MP exposure to seafood consumption. We assessed aquatic ecological risk quotients (RQ), oyster mortality exceedance risk (ER), human MP intake exposure, and human liver damage ER. Our data showed that MP abundances ranged from 0.025-4.701 items/m3 and 0.015-2.374 items/g (wet weight) in water and oysters, respectively. Although RQ values indicate negligible risk for aquatic ecosystems, but oyster mortality ER results from oysters exposed to MPs showed a 6% increase in mortality (10% risk). The probabilistic representation of risk curves of MPs for alanine aminotransferase (ALT) levels in human serum was found to be low, indicating minimal health risk to humans. Overall, our data suggest that relying on a single risk indicator may underestimate potential risks, multi-faceted tools are recommended for assessing organism and human health.

Combining size distribution and shape of plastic and oxide particles to evaluate physicochemical interactions: Aggregation and attachment

Particles naturally have size distributions and shapes, but these are overlooked in the physicochemical theory used to estimate interaction energies for particle aggregation or attachment. Consequently, the objectives of this research were to implement size distribution and shape in physicochemical interactions, and to use machine learning (ML) to investigate physicochemical parameters to interpret aggregation or attachment. A deep neural network was trained on databases generated for the interactions of spheres, ellipsoids, and cylinders. The primary sizes of particles were measured and then used in a machine learning model to predict interaction profiles considering size distributions. Spherical polystyrene and polymethyl-methacrylate were used in stability and aggregation experiments. Bullet- and fragment-like silica particles were used in attachment experiments. Subsequently, ML predictions were used to interpret the results of the experiments. The size distribution provides an active zone for physicochemical interactions that is absent using the traditional mean particle diameter (one equivalent sphere or ellipsoid). This is relevant because the size distribution increases the estimates of favorable and unfavorable aggregation and attachment. For example, these zones increase as the particle size distribution increases (high polydispersity index). Finally, although the approach is appropriate for spherical, ellipsoidal, and bullet-like particles, it is inappropriate for fragment-like particles, such as microplastics.

Riverine microplastics in the Mount Everest region affected by glacier meltwater

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

Fingerprinting risk from recycled plastic products using physical and chemical properties

The increasing production and use of recycled plastics have raised significant concerns regarding the risks associated with hazardous chemicals. The recycled plastics can accumulate potentially hazardous chemicals, many of which are unknown and unregulated. This study compared the physical and chemical characteristics of recycled plastic products intended for food, oral, or skin contact applications with similar virgin plastic products. The results revealed significant changes in the surface morphology and elevated concentration of organic and inorganic chemicals in the recycled plastics compared to the virgin plastics. Specifically, metal(loids) concentrations were over 10 times higher, PFAS levels were twice as high, and PAH levels were three times higher in the recycled plastics. The calculated Hazard Index (HI) indicates up to a twofold increase in recycled plastics for both adults and children compared to virgin plastics, specifically through microplastic ingestion. The HI values exceed 1 for recycled plastic ingestion, therefore it falls in high-risk category due to the associated chemical exposure from microplastics.

Effects of Micro- and Nanoplastic Exposure on Macrophages: A Review of Molecular and Cellular Mechanisms

Micro- and nanoplastics (MNPs), pervasive environmental pollutants, contaminate water, soil, air, and the food chain and ultimately accumulate in living organisms. Macrophages are the main immune cells that gather around MNPs and engulf them through the process of phagocytosis. This internalization triggers M1 polarization and the secretion of inflammatory cytokines, including IL-1, IL-18, IL-12, TNF-α, and IFN-γ. Furthermore, MNPs damage mitochondria and lysosomes, causing overactivation of iNOS and excessive production of ROS. This results in cellular stress and induce apoptosis, necroptosis, and, in some cases, metosis in macrophages. The internalization of MNPs also increases the expression of receptors, involving CD36, SR-A, LOX-1, and the macrophage receptor with a collagenous structure (MARCO) while decreasing ABCA-1 and ABCG-1. MNPs in adipose tissue macrophages trigger proinflammatory cytokine secretion, causing adipogenesis, lipid accumulation, insulin resistance, and the secretion of inflammatory cytokines in adipocytes. Various factors influence the rate of MNP internalization by macrophages, including size, charge, and concentration, which affect internalization through passive diffusion. Receptor-mediated phagocytosis of MNPs occurs directly via receptors like T-cell immunoglobulin and mucin domain containing 4 (TIM-4) and MARCO. The attachment of biomolecules, including proteins, antibodies, opsonins, or microbes to MNPs (forming corona structures) promotes indirect receptor-mediated endocytosis, as macrophages possess receptors like TLRs and FcγRIII. MNPs also cause gut dysbiosis, a risk factor for proinflammatory microenvironment and M1 polarization. Here, we review the mechanisms and consequences of MNP macrophage exposure, which is linked to autoimmunity, inflammation, and cardiometabolic syndrome manifestations, including atherosclerosis and obesity, highlighting the immunotoxicity of MNPs.

Toxicological effects and mechanisms of renal injury induced by inhalation exposure to airborne nanoplastics

Micro-nanoplastics (MNPs) are ubiquitously present in various natural habitats, and the kidney plays a critical role in eliminating metabolic waste from the body. Therefore, nephrotoxicity studies of MNPs are necessary. Consequently, we conducted a study utilizing a mouse model that underwent autonomous inhalation of polystyrene nanoplastics (PS-NPs) to investigate the impact of airborne nanoplastics (NPs) on kidney. The results demonstrated that airborne NPs could accumulate within the kidney subsequent to pulmonary entry. Transcriptome analysis showed that exposure to airborne NPs persistently interfered with important signaling pathways including oxidative stress, inflammation, and coagulation, which activated the NR4A1/CASP3 and TF/F12 signaling pathways. In vitro studies have shown that NPs were internalized by human kidney proximal tubular epithelial (HK-2) cells, leading to a range of pathological responses, and ultimately affecting cell fate. Furthermore, we pioneered the exposure of NPs to human kidney organoids. Our findings revealed a heightened sensitivity in kidney organoids towards NPs as compared to immortalized cell lines. This suggested that exposure to NPs could potentially inflict a more substantial toxic effect on the development of embryonic kidneys. In conclusion, this study has revealed the deleterious effects of exposure to airborne NPs on the mouse kidney.

Microplastics in groundwater: Environmental fate and possible interactions with coexisting contaminants

Microplastics (MPs) are emerging environmental pollutants which represent a serious threat to ecosystems and human health and have received significant attention from the global community. Currently, a growing number of studies have found the presence of MPs in groundwater. This study exhaustively reviewed varying degrees of recent publications in Web of Science database and investigated the characteristics of MPs (concentration, types, sizes and shapes) in groundwater ecosystems, their migration characteristics, and interactions with co-occurring contaminants. Results suggested that current global research on MPs in groundwater has primarily focused on countries such as India, South Korea, China, Italy and United States. Pollution levels of MPs in groundwater show significant variability, ranging from 0 to 6832 n/L. The predominant plastic polymer types include PP, PE, PS, PA, PET and PVC. The sources of MPs in groundwater are primarily classified as associated with natural processes and anthropogenic activities. The physical, chemical and biological properties can influence the migration of MPs into groundwater. Furthermore, MPs can act as carriers, interacting with co-occurring contaminants, thereby enhancing their migration and toxicity, potentially posing a threat to groundwater ecosystems and human health. Consequently, the major challenges and associated recommendations for forthcoming research on MPs in groundwater are proposed.

Key adsorbents and influencing factors in the adsorption of micro- and nanoplastics: A review

Microplastics and nanoplastics (MNPs) are emerging contaminants in drinking water sources that pose serious risks to human health and ecosystems. Several removal strategies, such as adsorption, exist but present challenges for their industrial scalability. This review provides a concise overview of MNP adsorption mechanisms and highlights the limited but critical exploration of column adsorption in the literature, emphasizing its importance for large-scale applications. Special attention is given to carbon-based materials due to their cost-effectiveness, environmental friendliness and sustainability. Other adsorbents (e.g., metal-organic frameworks, clays) are also discussed for their promising performance in realistic water matrixes. To predict and optimize the efficiency of adsorbents, leading simulation models are reviewed. Taken together, this work provides a comprehensive overview of the fundamental factors, such as adsorption mechanisms, adsorbent selection and experimental conditions, to optimize MNP adsorption. By highlighting the underexplored area of column-based processes, it provides valuable information to advance adsorption as a viable industrial-scale solution for MNP contamination.

Neurological Outcomes of Joint Exposure to Polystyrene Micro/Nanospheres and Silver Nanoparticles in Zebrafish

BACKGROUND

Micro/nanoplastics and silver nanoparticles (AgNPs) are emerging environmental contaminants widely detected in aquatic environments. However, previous research has primarily focused on the interactions between micro/nanoplastics and organic substances or heavy metals, whereas the interactions and combined toxic effects of micro/nanoplastics with AgNPs remain unclear.

OBJECTIVE

Our study aimed to investigate the effects and mechanisms of coexposure to AgNPs and polystyrene micro/nanospheres (PS M/NPs) on the nervous system, comparing the toxicity of AgNPs alone and in combination with PS M/NPs in larval zebrafish.

METHODS

We investigated the dynamics of AgNPs' (5  nm ) adsorption onto PS M/NPs (5 μ m / 100  nm ) using inductively coupled plasma-mass spectrometry. Zebrafish larvae were coexposed to PS M/NPs (200 μ g / L ) and AgNPs (10 μ g / L ) from 6 h post fertilization (hpf) to 72  hpf to ∼ 120  hpf to evaluate neuroinflammatory effects from multiple perspectives, including developmental abnormalities, oxidative stress, neurobehavioral differences, vascular development, immune responses, differences in gene expression, and differences upon neuroinflammation inhibitor addition.

RESULTS

Adsorption experiments showed PS M/NPs could stably adsorb AgNPs, with higher adsorption in smaller particles. Zebrafish larvae exposed to combined PS M/NPs and AgNPs demonstrated neurodevelopmental abnormalities, including developmental malformations, lower levels of locomotor activity, delayed response, and abnormal neuronal development. In addition, exposed zebrafish also exhibited disrupted neurodevelopmental markers, including vascular and apoptotic indicators, and oxidative stress and neuroimmune responses. Quantitative real-time polymerase chain reaction analysis showed differences in gene expression within neurotoxic pathways in PS M/NPs and AgNPs-exposed zebrafish, focusing on key genes in immunity, apoptosis, vascular, and neural development. Furthermore, these neurotoxic effects induced by combined exposure were alleviated following the introduction of the neuroinflammation inhibitor curcumin.

DISCUSSION

Our findings demonstrate that polystyrene nanospheres (PSNPs) intensified AgNPs-induced neurotoxicity in larval zebrafish, whereas polystyrene microspheres (PSMPs) had a lesser effect, indicating distinct gene regulation roles when combined with AgNPs. These findings enhance the assessment of environmental risks in settings with coexisting nanomaterials and microplastics, offering important insights for evaluating combined exposure risks. https://doi.org/10.1289/EHP14873.

Effect of pH and salinity on the release of polystyrene microplastics derived dissolved organic matter as revealed by experimental studies and molecular dynamic simulations

Microplastics-derived dissolved organic matter (MPs-DOM) poses a significant risk to aquatic systems. This study characterized MPs-DOM from polystyrene microplastics (PSMPs) upon photoaging in freshwater and seawater. For pristine PSMPs, plastic additives are the predominant substances in MPs-DOM. As the degree of aging increases, intermediates emerge as the new predominant substances in MPs-DOM. Both higher pH and salinity accelerate the aging of PSMPs and MPs-DOM release. Molecular dynamics simulations align with experiments showing that increased pH and salinity levels enhance the release of MPs-DOM. Interaction energy calculations revealed a link between MPs-DOM release amount and the interaction intensity between PSMPs and MPs-DOM. Generally, MPs-DOM having lower interaction energy with PSMPs is more liable to release, and aging of PSMPs leads to a decrease in their interaction energy with MPs-DOM. For example, the interaction energies in the pH 10 seawater system were slightly lower than those in the pH 7 seawater system. In the pH 7 seawater system, the interaction energy between butyl acetate and PSMPs was -41.97 kJ/mol, while in the pH 10 seawater system, this value was -26.86 kJ/mol. These insights are crucial for assessing the environmental behavior of MPs and MPs-DOM in aqueous environments.

Effect of solution pH on nanoplastic adsorption onto soil particle surface and the aggregation of soil particles

Nanoplastics (NPs) are increasingly recognized as an emerging threat to the geospheric environment, and the movement behavior of NPs in the geospheric environment should be clarified. The aggregation properties of NPs, their adsorption onto soil particle surfaces, and the aggregation properties of soil particles with adsorbed NPs are considered to affect their mobility in soil; however, these processes remain unclear. Here, polystyrene (PS) NP suspensions were agitated at pH 4, 7, and 10, and aggregate size of the PSNP was measured to clarify its homo-aggregation behavior. Additionally, batch experiments were conducted using PSNPs, fine sand, and soil in solutions of pH 4, 7, and 10 to clarify the PSNP adsorption and subsequent aggregation behaviors of the soil particles. The results demonstrated that the PSNPs used in this study did not aggregate even when the solution pH was changed because the negative value of the zeta potential was sufficiently large. The PSNPs adsorbed more onto soil particles with large specific surface areas and positive zeta potentials than that onto sand particles. The zeta potentials of the soil particles and PSNPs were influenced by the solution pH. Furthermore, the adsorption of PSNPs onto soil particles changed their aggregation properties. This study contributes to the understanding of the mobility of NPs in soil; however, further studies such as water flow experiments, simulations, and the effects of NPs on the food chain are required.

Spatial retention, absorption, transport, and enrichment of microplastics in mangrove sediment complex system

Mangrove areas are the major sink of pollutants such as microplastics (MPs, less than 5000 μm in diameter). The spatial retention, transport, and accumulation of microplastics (MPs) within the complex mangrove sediment system has become a hotspot in the field of emerging contaminants. In this study, the Xiaoguansha mangrove forest in Guangxi Province, China, was selected as a representative case to investigate the horizontal and vertical distribution of MPs in sediments. To elucidate the processes of MP retention, accumulation, and their downward transport into deeper soil layers, a combination of statistical methods was employed, including the Kruskal-Wallis one-way ANOVA, correlation analysis, regression fitting, and Structural Equation Model (SEM). The results showed that: (1) The average abundance of MPs in the mangrove area (2414.0 ± 1570.8 items/kg) was significantly higher-by a factor of 2.24-than that in the tidal flat areas, suggesting that mangroves play a vital role in seawater purification.(2) The MPs in the smaller size range (0-1000 μm) tend to accumulate more readily in mangrove areas compared to larger particles (1000-5000 μm), implying a heightened potential risk to environmental and ecosystem health.(3) With the increase in soil depth, exhibited an exponentially decreasing trend, primarily due to the well-developed root systems of mangroves and the physicochemical adsorption capacity of the surrounding sediments. (4) Spatial retention and sediment absorption contributed 67.2 % and 32.8 %, respectively, to the enrichment of MPs in mangrove areas. The SEM analysis confirmed that the distribution of MPs was primarily governed by extensive root system and dense physical structure of mangrove. In addition, adsorption effects driven by the fundamental physicochemical properties of the sediments also contributed to MP retention. The findings contribute to a deeper understanding of the behavior of MPs in the mangrove-covered water-sediment system.

Transport of microplastic-antibiotic co-contaminants in tidal zones

Microplastics (MPs) and antibiotics (ATs) are emerging contaminants with recognized negative effects on marine ecosystems. MPs can adsorb and transport ATs, posing combined toxic effects to marine organisms. Despite growing concerns, research remains limited on the MP-AT co-contaminants in tidal zones, which are home to numerous aquatic species and represent a particularly susceptible ecosystem. This study used polyethylene (PE) MPs and tetracycline (TC) to investigate the influence under various conditions, including sediment sizes, tidal cycles, and MP sizes, on the transport of MP-AT co-contaminants in tidal zones using a tidal cycle simulation system, which was designed to replicate the tidal dynamics and provide insights into the movement and behavior of contaminants. It was observed that MP-AT co-contaminants in tidal sediments exist in three distinct transport states. Smaller MP-AT co-contaminants (State 1) pass through sand pores and are widely distributed in the upper sediment layers, whereas larger MP-AT co-contaminants (State 2) concentrate in layers 1-5 due to size limitations. Agglomerated MP-AT co-contaminants (State 3), unable to pass through sand pores, accumulate at the bottom. Tidal cycles enhance MP-AT co-contaminant retention, while sand size (125-212 μm) limitedly affects their distribution. MP size played a crucial role, with larger MPs settling in layers 1-5 and smaller MPs remaining more dispersed. These findings emphasize the importance of MP size in affecting contaminant transport in tidal environments. Results from this research will contribute to the development of transport models and help predict the long-term environmental impact of MP-AT co-contaminants.

Mechanisms for iron oxide nanoparticle alleviation of nanoplastic-induced stress in Perilla frutescens revealed by integrated physiological and transcriptomic analysis

Nanoplastics, infiltrating soil ecosystems through diverse pathways such as agricultural practices, sludge application, and atmospheric deposition, present significant potential risks to global ecological systems. Through adsorption, iron oxide nanoparticles (IONPs) could reduce toxicity and bioavailability of nanoplastics in polluted soil ecosystems. However, little is known about how interactions between IONPs and polystyrene nanoplastics (PSNPs) affect plant growth. This study revealed that iron oxide nanoparticles (IONPs) effectively mitigated the uptake of polystyrene nanoplastics (PSNPs) in Perilla frutescens, demonstrating a substantial reduction of PSNPs accumulation by 46.15% in roots and 24.83% in stems. Furthermore, IONPs application significantly improved plant growth parameters, with notable increases of 20.40% in plant height and 34.22% in biomass compared to plants exposed solely to PSNPs.Compared with PSNPs alone, application of PSNPs + IONPs enhanced plant photosynthetic parameters, reduced the quantity of osmotic substances and reduced the activity of antioxidant enzymes. KEGG analysis was concentrated on photosynthetic metabolism and flavonoid synthesis. Further analysis combined with metabolic pathways revealed that IONPs treatment improved plant growth by up-regulating photosystem genes (PsbP, Psak, and PetC) and flavonoid synthesis genes (CHS, CHI, and F3H). Overall, IONPs enhance Perilla frutescens growth by upregulating photosystem-related genes and mitigate PSNPs-induced oxidative stress through flavonoid biosynthesis pathway activation. The present study provides new insights that will aid development of nano iron fertilizers capable of improving the adverse effects of nano plastics on agricultural production.

Influence of Polystyrene Microplastics on Mitochondrial Oxidative Damage in Renal and Muscular Tissues of the Freshwater Fish

Polystyrene microplastics (PS-MPs), an emerging environmental contaminant, have attracted significant concern in recent years. This study aimed to evaluate mitochondrial oxidative damage in renal and muscular tissues of the freshwater fish Anabas testudineus following exposure to environmentally relevant concentrations (13.6 mg L⁻1 and 23.6 mg L⁻1) of PS-MPs for 1, 7, and 15 days. Exposure to PS-MPs disrupted the antioxidant defense system within the mitochondrial compartments of renal and muscle tissues, leading to increased levels of hydrogen peroxide generation and lipid peroxidation. PS-MPs exposure altered metabolic functions in the mitochondrial fractions of kidney and muscle tissues, as evidenced by elevated activities of alanine aminotransferase and aspartate aminotransferase. Besides, exposure to PS-MPs resulted in a decline of tissue-specific marker enzymes, such as acid and alkaline phosphatases, in renal tissue, indicating tissue damage. Histological examinations revealed significant tissue damage, including necrosis of renal tubules, vacuolization, glomerular degeneration, and melanomacrophage aggregation in kidney tissues. In muscle tissues, the observed damages included myolysis, vacuolar degeneration, necrosis, and atrophy of muscle fibers. These findings suggest that oxidative stress induced by PS-MPs exposure disrupts metabolic functions in mitochondrial fractions, thereby providing valuable insights into nephrotoxicity and muscular toxicity in fish.

Guidelines toward ecologically-informed bioprospecting for microbial plastic degradation

Biological degradation of plastics by microbial enzymes offers a sustainable alternative to traditional waste management methods that often pollute the environment. This review explores ecologically-informed bioprospecting for microorganisms possessing enzymes suitable for biological plastic waste treatment. Natural habitats enriched in plastic-like polymers, such as insect-derived polyesters, epicuticular microbial biofilms in the phyllosphere of plants in extreme environments, or aquatic ecosystems, are highlighted as promising reservoirs for bioprospecting. Anthropogenic habitats, including plastic-polluted soils and the plastisphere, have yielded potent enzymes such as PETases and cutinases, which are being exploited in biotechnology. However, bioprospecting in plastispheres and artificial environments frequently leads to the isolation of environmental opportunistic microorganisms, such as Pseudomonas aeruginosa, Aspergillus fumigatus, Parengyodontium album, or species of Fusarium, which are capable of becoming human and/or plant pathogens. These cases necessitate stringent biosecurity measures, including accurate molecular identification, ecological assessment, and containment protocols. Beyond advancing bioprospecting approaches toward a broader scope of relevant habitats, this review underscores the educational value of such screenings, specifically, in understudied natural habitats, emphasizing its potential to uncover novel enzymes and microorganisms and engage the next generation of researchers in interdisciplinary study integrating environmental microbiology, molecular biology, enzymology, polymer chemistry, and bioinformatics. Finally, we offer guidelines for microbial bioprospecting in various laboratory settings, ranging from standard environmental microbiology facilities to high-biosecurity facilities, thereby maximizing the diversity of scientists who may contribute to addressing urgent environmental challenges associated with plastic waste.

The nano-paradox: addressing nanotoxicity for sustainable agriculture, circular economy and SDGs

Engineered nanomaterials (ENMs) have aroused extensive interest in agricultural, industrial, and medical applications. The integration of ENMs into the agricultural systems aligns with the principles of United Nations' sustainable development goals (SDGs), circular economy (CE) and bio-economy (BE) principles. This approach offers excellent opportunities to enhance productivity and address global climate change challenges. The revelation of the adverse effects of nanomaterials (NMs) on various organisms and ecosystems, however, has fueled the debate on 'Nano-paradox' leading to emergence of a new research domain 'Nanotoxicology'. ENMs have shown different interactions with biological and environmental systems as compared to their bulk counterparts. They bioaccumulate in organisms, soils, and other environmental matrices, move through food chains and reach higher trophic levels including humans ultimately resulting in oxidative stress and cellular damage. Understanding nano-bio interactions, the mechanism of gene- and cytotoxicity, and associated potential hazards, is therefore, essential to mitigate their toxicological outputs. This review comprehensively examines the cyto- and genotoxicity mechanisms of ENMs in biological systems, covering aspects such as their entry, uptake, cellular responses, dynamic interactions in biological environments their long-term effects and environmental risk assessment (ERA). It also discusses toxicological assessment methods, regulatory policies, strategies for toxicity management/mitigation and future research directions in nanotechnology, all within the context of SDGs, CE, promoting resource efficiency and sustainability. Navigating the nano-paradox involves balancing the benefits of nanomaterials with concerns about nanotoxicity. Prioritizing thorough research on above facets can ensure sustainability and safety, enabling responsible harnessing of nanotechnology's transformative potential in various applications including mitigating global climate change and enhancing agricultural productivity.

Widespread microplastic and nanoplastic contamination in the intestines of birds: A case study from Chengdu, China

Widespread pollution of microplastics (MPs) and nanoplastics (NPs) poses significant threats to organisms and human health. However, the extent of MPs and NPs contamination and their ecological risks to wildlife remain underexplored. In this study, we used Laser Direct Infrared (LDIR) spectroscopy to identify and characterize MPs in the intestinal contents of 49 bird species, and Pyrolysis-Gas Chromatography/Mass Spectrometry (Py-GC/MS) to identify NPs in the intestinal contents of five species. LDIR analysis indicated that chlorinated polyethylene (CPE) and polyvinyl chloride (PVC) were the most prevalent plastics among 32 identified types. MP particle sizes below 100 μm were most abundant, and MPs were predominantly in the form of fragments or pellets. We also found that birds with narrower dietary niche breadth had more MPs. Herbivorous and carnivorous birds had higher MP abundance than omnivorous species, which suggests the capacity of MP accumulation across diet categories. The Polymer Hazard Index (PHI) for MPs revealed that most species sampled were classified at hazard levels III or IV. Py-GC/MS identified four types of NPs in bird intestines, including nylon 66 (PA66), PVC, polyethylene (PE), and polypropylene (PP). This study advances our knowledge of plastic pollution ingested by terrestrial organisms and the risks associated with increased plastic pollution in the environment.

Formation mechanisms of carcinogenic N-nitrosamines from dissolved organic matter derived from nitrogen-containing microplastics during chloramine disinfection

The high occurrence of microplastics (MPs) in water treatment facilities may complicate the source-control of disinfection by-products. Herein, we reported that the carcinogenic N-nitrosamines, such as N-nitrosodimethylamine (NDMA) and N-nitrosodiethylamine (NDEA), were generated during monochloramine disinfection of water in which nitrogen-containing microplastics (N-MPs, such as polyamide and polyacrylonitrile) were present. The precursors of NDMA and NDEA were mainly derived from the dissolved organic matter released from N-MPs (N-MP-DOM), which were characteristic of a significantly higher proportion of polar and non-cationic fractions, favouring the N-nitrosamine formation. The results of excitation-emission-matrix spectra and orbitrap-mass spectrometry indicated that the polar components were mainly CHON and highly hydrogen-saturated molecules (H/C ≥ 1.5) (such as protein-like substrates), which are potential precursors of N-nitrosamines. Further mass difference network analysis revealed that the reactions of amine and nitro/nitroso groups in the precursors made predominant contribution to the generation of N-nitrosamines. Two potent NDMA precursors bearing a (CH3)2N-R structure were identified based on the diagnostic fragments (e.g., 45.0578 Da and m/z 58.0651) and in silico fragmentation tool (MetFrag 2.2) in MS2 spectra. Our findings provide valuable insights into understanding the potential risks of N-MPs due to monochloramine disinfection in water treatment systems.

Interactive toxicity effects of metronidazole, diclofenac, ibuprofen, and differently functionalized nanoplastics on marine algae Chlorella sp

Pharmaceutical products (PPs) and nanoplastics (NPs) are prominent emerging contaminants that pose serious threats to marine ecosystems. The present study aimed to investigate both pristine and combined toxicity of PPs (metronidazole, diclofenac, and ibuprofen) and polystyrene nanoplastics (PSNPs) with amine (NH2-PSNPs) and carboxyl (COOH-PSNPs) surface functionalization on marine microalgae Chlorella variabilis. Toxicity assessment included the evaluation of growth inhibition, total reactive oxygen species production, malondialdehyde content, antioxidant activity, and photosynthetic activity. Furthermore, changes in the surface functional groups of the algae after exposure to contaminants were examined. The correlation among the toxicity endpoints was assessed using Pearson correlation and cluster heatmap analysis. Zeta potential analysis and hydrodynamic size measurements revealed that the PSNPs became unstable in the presence of PPs. This instability facilitated the aggregation and rapid settlement of PSNPs, consequently impeding their direct interaction with algal cells. Growth inhibition results indicated that Chlorella variabilis exhibited minimal growth inhibition when exposed to pristine PPs (1 mg L-1), whereas PSNPs (1 mg L-1) caused substantial growth inhibition. Notably, the combined toxicity of PSNPs and PPs was lower compared to pristine PSNPs. The independent action model revealed that the combination of PPs and PSNPs showed an antagonistic mode of interaction. The potential reasons for the decreased toxicity observed in the mixture of PSNPs and PPs compared to pristine PSNPs can be attributed to diminished oxidative stress and enhanced photosynthetic activity. These findings provide valuable insights into the role of PPs in modulating the toxicity of PSNPs towards microalgae.

Understanding the seasonal variation of the microplastics occurrence and source in the water source: upstream of the Huangpu River in Shanghai as an example

The potential seasonal variations in the features and sources of microplastics (MPs) in reservoirs and the connected upstream rivers remain poorly understood. A field study of MPs in Huangpu River upper reaches indicated that surface water MP abundance was 4.75 ± 0.63 (Taipu River), 5.8 ± 0.9 (Lanlugang River), and 4.3 ± 0.9 items/L (Jinze Reservoir) during wet season, increasing to 12.9 ± 1.4, 18 ± 1.7, and 8.3 ± 1.7 items/L, respectively in drought season, whereas in sediment was 6704 ± 421, 3932 ± 200, and 4737 ± 408 items/kg during wet season, which decreased to 4045 ± 523, 4017 ± 430, and 2229 ± 434 items/kg during drought period. The MPs mainly comprised PE, PP fragments/fibers, and PET fibers. The significant seasonal variations in MP abundance were detected only within the surface water and sediments of rivers. Notably, significant seasonal variations in the features of MPs were observed in the surface water of Jinze Reservoir and the surface water or the sediments of rivers. During the wet season, multiple potential sources of MPs were identified in the reservoir, whereas the Taipu River served as the primary source during drought periods. Moderate or lower MP abundance was observed within the surface water of upper reaches of the Huangpu River, while higher levels were found in the sediments. The findings suggest Jinze Reservoir's MP control requires seasonal adjustments. While upper Huangpu River surface water shows lower risk with good safety, MP migration to sediments elevates risks, necessitating prioritized sediment management.

Subchronic Exposure to Polystyrene Nanoplastics Disrupts Placental Development and Calcium Homeostasis: Insights from In Vivo and In Vitro Models

Nanoplastics have recently emerged as persistent pollutants of global concern that pose substantial risks to human health. However, the long-term adverse effects of nanoplastics on the female reproductive system remain unclear. Polystyrene nanoplastics (PS-NPs; 50 nm diameter) were selected as representative nanosized plastic particles to investigate the potential effects of subchronic prenatal and gestational exposure via drinking water on placental development in ICR (CD-1) mice. Maternal exposure to 10 mg/L PS-NPs induced an increase in fetal resorption rate and significantly increased fetal weight. Further observation of the placental morphology showed that PS-NPs exposure led to an aberrant placental structure and damaged the trophoblast cells. At the cellular level, PS-NPs exposure promoted the proliferation, migration, and invasion of HTR-8/SVneo cells. Mechanistically, transcriptomic and proteomic analyses revealed that PS-NPs triggered placental calcium disturbances and upregulated the Stam2 expression in mice. STAM2 induced by PS-NPs mediates the disruption of trophoblastic calcium homeostasis and regulates cell functions by disturbing the lysosomal degradation of the calcium channel protein IP3R3 and promoting intracellular calcium inflow by increasing the level of TRPV6 in HTR-8/SVneo cells. Therefore, our results indicated that trophoblastic calcium dyshomeostasis is the main mechanism by which subchronic PS-NPs exposure induces abnormal placental development. These findings reveal a link between subchronic PS-NPs exposure and placental damage and elucidate the underlying molecular mechanism, providing evidence for environmental triggers of adverse pregnancy and highlighting the risk of plastic products to pregnant women.

Understanding the structure, distribution, and retention of nanoplastics in montmorillonite nanopore by multi-scale computational simulations

The interfacial adsorption, aggregation and deposition processes of nanoplastics (NPs) on clay mineral surfaces critically regulate their environmental mobility, transformation pathways, and ecotoxicological risks in aquatic ecosystems. A quantitative understanding of the nanoscale interfacial processes is essential. This study employs molecular dynamics (MD) simulations and density functional theory (DFT) calculations to elucidate the aggregation and deposition mechanisms of three types of NPs in their pristine and aged states in the nanopore solution of montmorillonite (Mt). In the wet environment, NPs tend to form aggregates in the nanopore and migrate in solution, increasing environmental risk, while in the dry environment, NPs are more likely to deposit on the basal surface to form larger aggregates, consequently reducing their mobility. Results show hydrophobic interactions play as the primary driving force for the aggregation of pristine NPs, and both hydrophilic and hydrophobic interactions contribute to the aggregation of aged NPs. Aged NPs exhibit stronger binding affinity to Mt through mechanism such as Ca²⁺ bridging and hydrogen bonding, compared to their pristine counterparts. DFT calculations further reveal the formation of hydrogen bonds between the hydroxyl groups of aged NPs and the tetrahedral oxygen atoms in Mt. Through atomic-level characterization of interfacial processes, this work establishes a predictive framework for NP environmental behavior by resolving migration dynamics and retention processes in nanopore water.

Impact of Microplastics on Ciprofloxacin Adsorption Dynamics and Mechanisms in Soil

The co-occurrence of microplastics (MPs) and antibiotics as emerging contaminants demonstrates significant ecological perturbations in soil matrices. Of particular scientific interest is the potential for MPs to mediate the environmental fate and transport dynamics of co-existing antibiotics. This study investigated MP-mediated ciprofloxacin (CIP) adsorption in lateritic soils. Batch experiments with polyethylene (PE), polypropylene (PP), and poly (ethylene-terephthalate) (PET) revealed soil components dominated CIP retention, while 10% (w/w) MPs reduced soil adsorption capacity by ≥10.8%, with inhibition intensity following PET > PE > PP. Adsorption thermodynamics exhibited significant pH dependence, achieving maximum sorption efficiency at pH 5.0 (± 0.2), which was approximately 83%. Competitive adsorption analysis demonstrated inverse proportionality between ionic strength and CIP retention, with trivalent cations exhibiting superior competitive displacement capacity compared to mono- and divalent counterparts. Isothermal modeling revealed multilayer adsorption mechanisms governed by hybrid chemisorption/physisorption processes in both soil and MP substrates. Spectroscopic characterization suggested differential adsorption pathways: MP-CIP interactions were primarily mediated through hydrophobic partitioning and π-π electron coupling, while soil-MP composite systems exhibited dominant cation exchange capacity and surface complexation mechanisms. Notably, electrostatic attraction/repulsion forces modulated adsorption efficiency across all experimental conditions, particularly under varying pH regimes. This work advances understanding of co-contaminant dynamics in soil ecosystems, informing risk assessment frameworks.

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

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

Transport dynamics of microplastics within aquatic vegetation featuring realistic plant morphology

Despite the significance of rivers and streams in transporting terrestrial microplastics (MP) to the oceans, limited research has focused on the role of aquatic vegetation and their complex geometry in shaping the underlying mechanisms governing MP mixing and dispersion processes in riverine environments. This study, for the first time, investigates the transport and fate of non-buoyant MPs, specifically those with diameters of 188 nm and 6μm and a density of 1.04 g/cm3, in floating Eichhornia crassipes canopies under flow conditions typical of natural rivers (0.0167-0.0667 m/s). Physical modelling tests reveal that aquatic vegetation significantly alters the hydrodynamic structure and enhances the dissipation of turbulence in the water column, leading to decreased velocities, diversified length scales, and increased turbulent kinetic energy (TKE) in regions with higher frontal vegetation areas. This turbulence, in turn, facilitated momentum exchange and vertical mixing, particularly in regions with the most pronounced frontal area changes. Wider canopy spacing promoted the evolution of wake turbulence and facilitated wake expansion throughout the water column, generating coherent structures that effectively doubled the integral length scales with increasing distance between canopies from 0.5 m to 1.5 m. This adjustment resulted in a more uniformly dispersed downstream movement of MPs. Notably, the presence of canopies amplified MP diffusivity by 10-40 times compared to equivalent unvegetated conditions, transitioning the primary mixing mechanism from shear-induced velocity gradients to turbulence enhanced by plant-flow interactions. This study offers a robust framework for quantifying MP mixing and predicting longitudinal dispersion coefficients within the floating vegetated flows, by developing models that depict the vertical profiles of TKE and turbulent diffusivity featured by canopy morphology and spacing. The insights from this study make a significant contribution towards improving our ability to predict the mixing and fate of MPs in riverine environments and underscore the necessity of incorporating the complex dynamics of aquatic vegetation into environmental management and MP risk assessments.

Epigenetic and Gene Expression Responses of Daphnia magna to Polyethylene and Polystyrene Microplastics

Microplastics (MPs), ubiquitous environmental pollutants, pose substantial threats to aquatic ecosystems and organisms, including the model species Daphnia magna. This study examined the effects of polyethylene (PE) and polystyrene (PS) MPs on D. magna, focusing on their ingestion, epigenetic alterations, and transcriptional responses. Exposure experiments revealed a concentration-dependent accumulation of MPs, with PS particles showing higher ingestion rates due to their higher density and propensity for aggregation. Epigenetic analyses demonstrated that exposure to PE MPs significantly reduced the global DNA methylation (5-mC) of Daphnia magna, suggesting hypomethylation as a potential stress response. Conversely, the DNA hydroxymethylation (5-hmC) of Daphnia magna displayed variability under PS exposure. Transcriptional analysis identified a marked downregulation of Vitellogenin 1 (v1) and upregulation of Ecdysone Receptor B (ecr-b), highlighting the occurrence of stress-related and adaptive molecular responses. These findings enhance our understanding of the molecular and epigenetic effects of MPs on aquatic organisms, offering critical insights for the development of effective environmental management and conservation strategies in the face of escalating MP pollution.

Interfacial sorption of 17β-E2 on nano-microplastics: Effects of particle size, functional groups and hydrochemical conditions

Nano-microplastics and 17β-E2 have been frequently detected as emerging high-concern pollutants in aquatic systems, and their interaction at the solid/liquid interface has become a research focus in environmental studies. The interfacial sorption kinetics and equilibrium characteristics of 17β-estradiol (17β-E2) on nano-polystyrene (Nano-PS) with different particle sizes and organic functional group modifications were systematically investigated in aqueous environments in this study. The interfacial interaction mechanism between Nano-PS particles and 17β-E2 was elucidated by utilizing SEM, FTIR, XPS and BET techniques. The experimental results demonstrated that the interfacial sorption kinetics of 17β-E2 on different Nano-PS were rapid, in accordance with the pseudo-first-order models. Both Langmuir and Freundlich models provided a nice description of 17β-E2 sorption equilibrium on Nano-PS, indicating that physical effects predominantly governed the interfacial interactions. Modification of Nano-PS by -OH and -NH2 resulted in increase in polarity, decrease in hydrophobicity and reduction in the sorption capacity for 17β-E2, suggesting that hydrophobic partitioning primarily controlled the interfacial interaction between Nano-PS and 17β-E2. Furthermore, the superior sorption capacity of PS100-OH relative to PS100-NH2 can primarily be attributed to the enhanced hydrogen bonding capability provided by the -OH group. The sorption capacity of 17β-E2 by the same Nano-PS was inversely proportional to the particle size, indicating that a smaller particle size possessed larger specific surface area, thereby providing more active sites and facilitating more pore filling. Low temperature promoted the sorption process and increased the sorption capacity. This study established a scientific foundation for better assessment of the environmental behavior arising from co-pollution of nano-microplastics and endocrine disruptors (EDCs).

Micro- and nano-plastics pollution in the marine environment: Progresses, drawbacks and future guidelines

Marine pollution by micro/nanoplastics (M/NPs) has emerged as a critical global issue, with widespread ecological and economic consequences. Numerous studies have investigated M/NPs pollution in marine environments, but there remains a need to assess progress, identify challenges, and propose future strategies. This review provides updated insights into marine M/NPs, including their sources, detection methods, global data from diverse marine ecosystems, and the challenges in mitigating pollution. The review reveals that the ocean harbors approximately 5.25 trillion plastic debris pieces, with a total of 50-75 trillion plastic and microplastic particles, with deep-sea regions containing up to 4 billion plastic microfibers per square kilometer. Human activities, including industrial practices and aquaculture, are major contributors to M/NPs pollution, which threatens 17% of marine species and incurs an economic loss of 6-9 billion USD. M/NPs are found across various marine habitats, including shorelines, sea floors, water columns, biota, and floating debris. Analyzing nanoplastics is particularly challenging due to their heterogeneous aggregation with other contaminants and their much lower concentrations than natural particles. Key drawbacks in addressing M/NPs pollution include inadequate funding, insufficient regulations, and a lack of policy frameworks on the prevalence, distribution, and sources of M/NPs. There is an increasing focus on utilizing innovative technologies such as artificial intelligence (AI) to monitor, assess risks, and predict the spread of M/NPs. Therefore, urgent global cooperation, involving all stakeholders and the general public, is essential. Additionally, integrating scientific and engineering methods, along with AI technologies, is crucial for monitoring and controlling M/NPs pollution and developing sustainable solutions.

Characteristics and influencing factors of microplastics entering human blood through intravenous injection

The presence of microplastics in the human body and their potential health risks have drawn widespread attention in recent years. Microplastics have been detected in human blood, though their pathways of entry remain unclear. This study employed Raman spectroscopy and energy dispersive spectroscopy to evaluate the microplastic release characteristics of intravenous medical devices, aiming to investigate the influencing factors and the risk of microplastics entering the bloodstream. The results showed that microplastics were found in three widely-used medical devices, with abundances ranging from 0.44 to 2.00 items/n. Polyethylene, polypropylene (46.2 %), fragments (96.7 %), and white (86.8 %) were the predominant characteristics. Factors such as brand, specifications, and usage scenarios influence microplastic release, leading to differences in detection rates among different medical devices (0-100%). Repeated use significantly increases the risk of microplastic release (p < 0.05). Notably, built-in filtration membranes do not completely retain microplastics and may pose a risk of shedding fibers themselves. Using the exposure assessment model, the estimated microplastic release per person per year was 3.75 items for syringe, 6.22 items for infusion set, and 0.35 items for vein detained needle. Overall, although the amount of microplastics entering the human body through intravenous injection is significantly lower than that from dietary exposure and other pathways, the risk of direct entry into the bloodstream remains a concern. This research provides critical evidence for understanding the direct pathways and risks of microplastic exposure in human blood from plastic medical devices, offering significant scientific value for assessing exposure pathways and the safety of medical device use.

Microplastics in freshwater and marine ecosystems: Occurrence, characterization, sources, distribution dynamics, fate, transport processes, potential mitigation strategies, and policy interventions

Most of the literature on microplastics (MPs) focuses on freshwater or terrestrial ecosystems, frequently overlooking their interconnections with the marine environments. This oversight is worrying given that both ecosystems serve as primary pathways for the introduction of MPs into marine environments. This review synthesizes existing literature on MPs in both freshwater and marine ecosystems across all six continents. The most commonly produced plastic polymers in industry are polyethylene (36 %) and polypropylene (21 %), and studies revealed that these two materials are the most abundant in aquatic ecosystems. Primary and secondary MPs originate from a range of sources including land-based disposal, the ocean, airborne deposition, wastewater treatment facilities, automobiles, pharmaceuticals and personal care products, synthetic textiles, and insect repellents. Notably, secondary MPs, which are formed from the breakdown of larger plastic items comprise approximately 69-81% of marine debris, especially in urbanized, densely populated areas. The inconsistencies of the methodologies (sampling, extraction, and quantification) and the units employed for result presentations are part of the major limitations in MPs research. Environmental phenomena such as heteroaggregation, weathering, adsorption, leaching, and fragmentation are the major factors influencing the behavior, fate, and degradation process of plastic particles. The physicochemical properties of plastic polymers, such as density, crystallinity, as well as bioturbation, meteorological forces, and wind actions, including currents, waves, and tides, are responsible for biofouling, aggregation, sinking into the bottom sediment, resuspension, and the vertical, horizontal, and spatiotemporal distributions and transport of MPs. The potential solutions to mitigate plastic pollution are grounded in the 3Rs framework, which includes reducing production and consumption, advancing the biotechnological, chemical and microbial development of degradable polymers, promoting reusable plastic products with lower environmental impacts over their lifetimes, and recycling waste into new products. The regulatory policies on single-use plastics commonly involve permanent bans and financial penalties for violators. In addition, nations such as the United States, the Netherlands, and northern Europe have introduced economic incentives to encourage the return of reusable materials to reduce plastic waste and the resulting envrionmental pollution.

Influence of anthropogenic pressures on the microplastic distribution in the riverine-estuarine environment: A source-apportioning approach

In this study, the influence of anthropogenic pressures, namely fishing practices and illicit and unregulated wastewater and solid waste discharge, on the microplastic distribution in India's Kallada River - Ashtamudi riverine-estuarine environment was investigated. To better characterize microplastic pollution in the Estuary, it was subdivided into cage farming, open fishing, solid waste dumping, and other zones that receive wastewater from residential areas. A source-apportioning approach was utilized to delineate the possible sources of pollution and conducted a risk assessment attributed to exposure to microplastic pollution. The results suggest that the solid waste dumping zone exhibited the highest microplastic abundance, followed by the cage farming zone. Fiber-shaped microplastic particles were abundant in cage farming and open fishing zones, while films dominated the solid waste dumping zone. FTIR analysis revealed that polyamide and polyester, widely used for regional fishing nets, were dominant in cage farming and open fishing zones, while polyamide, polystyrene, and polyethylene were dominant in solid waste dumping zones. Other zones impacted by the unregulated discharge of domestic wastewater exhibited an abundance of polyester and polyethylene microplastics. Source apportionment studies using a modified approach incorporating morphological and chemical characteristics of microplastics revealed that fishing nets/ropes contributed to 35.48 % of microplastic pollution, followed by single-use plastics and plastic bags/covers (19.35 % each), textile fabrics (16.13 %) and personal care products (9.68 %). A risk assessment analysis considering microplastic abundance and polymer hazard revealed that the solid waste dumping zone and the cage farming zone pose a medium risk to microplastic pollution. These findings highlight the role of fishing practices and solid waste dumping on the microplastic pollution in the riverine-estuarine environment.

Acute Exposure to Aerosolized Nanoplastics Modulates Redox-Linked Immune Responses in Human Airway Epithelium

Micro- and nanoplastics (MPs and NPs) are pervasive environmental pollutants detected in aquatic ecosystems, with emerging evidence suggesting their presence in airborne particles generated by water body motion. Inhalation exposure to airborne MPs and NPs remains understudied despite documented links between occupational exposure to these particles and adverse respiratory outcomes, including airway inflammation, oxidative stress, and chronic respiratory diseases. This study explored the effects of acute NP exposure on a fully differentiated 3D human airway epithelial model derived from 14 healthy donors. Airway epithelium was exposed to aerosolized 50 nm polystyrene NPs at concentrations ranging from 2.5 to 2500 µg/mL for three minutes per day over three days. Functional assays revealed no significant alterations in tissue integrity, cell survival, mucociliary clearance, or cilia beat frequency, suggesting intact epithelial function post-exposure. However, cytokine and chemokine profiling identified a significant five-fold increase in CCL3 (MIP-1α), a neutrophilic chemoattractant, in NP-exposed samples compared to controls. This was corroborated by increased neutrophil chemotaxis in response to conditioned media from NP-exposed tissues, indicating a pro-inflammatory neutrophilic response. Conversely, levels of interleukins (IL-21, IL-2, IL-15), CXCL10, and TGF-β were significantly reduced, suggesting immunomodulatory effects that may impair adaptive immune responses and tissue repair mechanisms. These findings demonstrate that short-term exposure to NP-containing aerosols induces a distinct pro-inflammatory response in airway epithelium, characterized by enhanced neutrophil recruitment and reduced secretion of key immune modulators. These findings underscore the potential for aerosolized NPs to induce oxidative and inflammatory stress, raising concerns about their long-term impact on respiratory health and redox regulation.

Interaction of Polystyrene Nanoplastics with Biomolecules and Environmental Pollutants: Effects on Human Hepatocytes

The inevitable exposure of humans to micro/nanoplastics has become a pressing global environmental issue, with growing concerns regarding their impact on health. While the direct effects of micro/nanoplastics on human health remain largely unknown, increasing attention is being given to their potential role as carriers of environmental pollutants and organic substances. This study investigates the direct toxicity of 500 nm polystyrene nanoplastics (NPs) on human hepatocytes (HepG2) in vitro, both alone and in combination with cadmium (Cd), a hazardous heavy metal and a prevalent environmental pollutant. One-hour exposure to 100 µg/mL of NPs causes a significant increase in ROS production (+25% compared to control) but cell viability remains unaffected even at concentrations much higher than environmental levels. Interestingly, NPs significantly reduce Cd cytotoxicity at LC50 concentrations (cell viability compared to control: 55.4% for 50 µM Cd, 66.9% for 50 µM Cd + 10 µg/mL NPs, 68.4% for 50 µM Cd + 100 µg/mL NPs). Additionally, NPs do not alter the cellular lipid content after short-term exposure (24 h). However, when Cd and fatty acids are added to the medium, NPs appear to sequester fatty acids, reducing their availability and impairing their uptake by cells in a dose-dependent manner. We confirmed by Dynamic Light Scattering and Scanning Electron Microscopy the interaction between NPs, Cd and free fatty acids. Although polystyrene NPs exhibited minimal cytotoxicity in our experimental model, collectively our findings suggest that predicting the effects of cell exposure to NPs is extremely challenging, due to the potential interaction between NPs, environmental pollutants and specific components of the biological matrix.