Hydrophobic sorption behaviors of 17β-Estradiol on environmental microplastics

Negligible additive effect of environmental concentrations of fragmented polyethylene terephthalate microplastics on the growth and reproductive performance of Java medaka exposed to 17β-estradiol and bisphenol A

To investigate whether environmental concentrations of fragmented polyethylene terephthalate (PET) microplastics (MPs) have additional or combined effects on endocrine-disrupting activity, Java medaka (Oryzias javanicus) were exposed to 17β-estradiol (E2; 5, 10, 50, and 100 ng L-1), bisphenol A (BPA; 5, 10, 50, and 100 µg L-1), and E2 and BPA combined with PET MPs (1 and 100 particles L-1) for 200 days. The growth parameters, such as body length and weight, were significantly decreased by the highest concentrations of E2 and BPA. A significant reduction in egg production was observed in female fish exposed to BPA, with an additive toxic effect of PET MPs. A female-biased sex ratio was observed in fish exposed to both chemicals. Exposure to E2 significantly increased the hepatosomatic index (HSI) in both sexes, while no significant effect was observed in the gonadosomatic index (GSI). Exposure to BPA significantly increased the HSI in female fish and decreased the GSI in both sexes of fish. An additive effect of PET MPs was observed on the GSI value of female exposed to BPA. Significant elevations in vitellogenin (VTG) levels were observed in both sexes due to exposure to E2 and BPA. Additive effects of PET MPs were observed on VTG levels in males exposed to E2 and BPA. Taken together, even long-term treatment with PET MPs induced only a negligible additive effect on the endocrine-disrupting activity in Java medaka at environmentally relevant concentrations.

Identification and quantification of micro-nano-plastics in polypropylene-bottled injections

Micro-nano-plastic (MNP) particles (p) in the environment can enter the human body and pose a potential threat to human health. However, it is unknown whether these substances are present in polypropylene (PP) plastic-bottled injections, which are used as high-frequency intravenous infusions to treat diseases. Therefore, the objective of this study was to identify and quantify insoluble MNP particles in 16 batches of injectable formulations within the validity period. Primarily, ethylene-propylene copolymer or P(E-P) micro-plastic (MP) particles (2-10 μm, 216 p/mL) were identified by micro-Raman spectroscopy, and nano-particles (<50 nm, 2.1 × 104 p/mL) similar to PP containing only carbon were detected by scanning electron microscopy-energy-dispersive X-ray spectroscopy (photoelectron). Furthermore, P(E-P) MP particles (1 × 103 to 1 × 105 ng/L) from the injections were enriched on the GF-B filter, and PP or P(E-P) nano-plastic (NP) particles (1 × 103 to 4 × 104 ng/L) enriched on the alumina film were detected by pyrolysis-gas chromatography/mass spectrometry. Finally, the total insoluble particles in injections were 6 × 104 to 1 × 107 p/mL (0.02-100 μm). Our findings are the first to identify and quantify MNPs in PP-bottled injections. Considering that they can enter the blood circulation, so whether cause disease remains to be investigated.

Exploring the co-exposure effects of environmentally relevant microplastics and an estrogenic mixture on the metabolome of the Sydney rock oyster

In aquatic environments the concurrent exposure of molluscs to microplastics (MPs) and estrogens is common, as these pollutants are frequently released by wastewater treatment plants into estuaries. Therefore, this study aimed to evaluate the independent and co-exposure impacts of polyethylene microplastics (PE-MPs) and estrogenic endocrine-disrupting chemicals (EEDCs) at environmentally relevant concentrations on polar metabolites and morphological parameters of the Sydney rock oyster. A seven-day acute exposure revealed no discernible differences in morphology; however, significant variations in polar metabolites were observed across oyster tissues. The altered metabolites were mostly amino acids, carbohydrates and intermediates of the Kreb's cycle. The perturbation of metabolites were tissue and sex-specific. All treatments generally showed an increase of metabolites relative to controls - a possible stimulatory and/or a potential hormetic response. The presence of MPs impeded the exposure of adsorbed and free EEDCs potentially due to the selective feeding behaviour of oysters to microplastics, favouring algae over similar-sized PE-MPs, and the formation of an eco/bio-corona involving faeces, pseudo-faeces, natural organic matter, and algae.

Microplastics and Co-pollutants in soil and marine environments: Sorption and desorption dynamics in unveiling invisible danger and key to ecotoxicological risk assessment

Microplastics (MPs) and their co-pollutants pose significant threats to soil and marine environments, necessitating understanding of their colonization processes to combat the plastic pandemic and protect ecosystems. MPs can act as invisible carriers, concentrating and transporting pollutants, leading to a more widespread and potentially toxic impact than the presence of either MPs or the pollutants alone. Analyzing the sorption and desorption dynamics of MPs is crucial for understanding pollutants amplification and predicting the fate and transport of pollutants in soil and marine environments. This review provides an in-depth analysis of the sorption and desorption dynamics of MPs, highlighting the importance of considering these dynamics in ecotoxicological risk assessment of MPs pollution. The review identifies limitations of current frameworks that neglect these interactions and proposes incorporating sorption and desorption data into robust frameworks to improve the ability to predict ecological risks posed by MPs and co-pollutants in soil and marine environments. However, failure to address the interplay between sorption and desorption can result in underestimation of the true impact of MPs and co-pollutants, affecting livelihoods and agro-employments, and exacerbate poverty and community disputes (SDGs 1, 2, 3, 8, 9, and 16). It can also affect food production and security (SDG 2), life below water and life on land (DSGs 14 and 15), cultural practices, and natural heritage (SDG 11.4). Hence, it is necessary to develop new approaches to ecotoxicological risk assessment that consider sorption and desorption processes in the interactions between the components in the framework to address the identified limitations.

Interaction of microplastics with perfluoroalkyl and polyfluoroalkyl substances in water: A review of the fate, mechanisms and toxicity

It is well known that microplastics can act as vectors of pollutants in the environment and are widely spread in freshwater and marine environments. PFAS (perfluoroalkyl and polyfluoroalkyl substances) can remain in the aqueous environment for long periods due to their wide application and good stability. The coexistence of microplastics and PFAS in the aqueous environment creates conditions for their interaction and combined toxicity. Studies on adsorption experiments between them and combined toxicity have been documented in the literature but have not been critically summarized and reviewed. Therefore, in this review, we focused on the interaction mechanisms, influencing factors, and combined toxicity between microplastics and PFAS. It was found that surface complexation may be a new interaction mechanism between microplastics and PFAS. In addition, aged microplastics reduce the adsorption of PFAS due to the presence of oxygenated groups on the surface compared to virgin microplastics. Attached biofilms can increase the adsorption capacity and create conditions for biodegradation. And, the interaction of microplastics and PFAS affects their spatial and temporal distribution in the environment. This review can provide insights into the fate of microplastics and PFAS in the global aquatic environment, fill knowledge gaps on the interactions between microplastics and PFAS, and provide a basic reference for assessing their combined toxicity.

Microplastics supply contaminants in food chain: non-negligible threat to health safety

The occurrence of microplastics (MPs) and organic pollutants (OPs) residues is commonly observed in diverse environmental settings, where their interactions can potentially alter the behavior, availability, and toxicity of OPs, thereby posing risks to ecosystems. Herein, we particularly emphasize the potential for bioaccumulation and the biomagnification effect of MPs in the presence of OPs within the food chain. Despite the ongoing influx of novel information, there exists a dearth of data concerning the destiny and consequences of MPs in the context of food pollution. Further endeavors are imperative to unravel the destiny and repercussions of MPs/OPs within food ecosystems and processing procedures, aiming to gain a deeper understanding of the joint effect on human health and food quality. Nevertheless, the adsorption and desorption behavior of coexisting pollutants can be significantly influenced by MPs forming biofilms within real-world environments, including temperature, pH, and food constituents. A considerable portion of MPs tend to accumulate in the epidermis of vegetables and fruits, thus necessitating further research to comprehend the potential ramifications of MPs on the infiltration behavior of OPs on agricultural product surfaces.

When antibiotics encounter microplastics in aquatic environments: Interaction, combined toxicity, and risk assessments

Antibiotics and microplastics (MPs), known as emerging pollutants, are bound to coexist in aquatic environments due to their widespread distribution and prolonged persistence. To date, few systematic summaries are available for the interaction between MPs and antibiotics in aquatic ecosystems, and a comprehensive reanalysis of their combined toxicity is also needed. Based on the collected published data, we have analyzed the source and distribution of MPs and antibiotics in global aquatic environments, finding their coexistence occurs in a lot of study sites. Accordingly, the presence of MPs can directly alter the environmental behavior of antibiotics. The main influencing factors of interaction between antibiotics and MPs have been summarized in terms of the characteristics of MPs and antibiotics, as well as the environmental factors. Then, we have conducted a meta-analysis to evaluate the combined toxicity of antibiotics and MPs on aquatic organisms and the related toxicity indicators, suggesting a significant adverse effect on algae, and inapparent on fish and daphnia. Finally, the environmental risk assessments for antibiotics and MPs were discussed, but unfortunately the standardized methodology for the risk assessment of MPs is still challenging, let alone assessment for their combined toxicity. This review provides insights into the interactions and environment risks of antibiotics and MPs in the aquatic environment, and suggests perspectives for future research.

Bark and biochar in horizontal flow filters effectively remove microplastics from stormwater

Organic materials such as bark and biochar can be effective filter materials to treat stormwater. However, the efficiency of such filters in retaining microplastics (MPs) - an emerging stormwater pollutant - has not been sufficiently studied. This study investigated the removal and transport of a mixture of MPs commonly associated with stormwater. Different MP types (polyamide, polyethylene, polypropylene, and polystyrene) were mixed into the initial 2 cm material of horizontal bark and biochar filters of 25, 50, and 100 cm lengths. The MP types consisted of spherical and fragmented shapes in size ranges of 25-900 μm. The filters were subjected to a water flow of 5 mL/min for one week, and the total effluents were analyzed for MPs by μFTIR imaging. To gain a deeper insight, one 100 cm bark filter replica was split into 10 cm segments, and MPs in each segment were extracted and counted. The results showed that MPs were retained effectively, >97%, in all biochar and bark filters. However, MPs were detected in all effluents regardless of filter length. Effluent concentrations of 5-750 MP/L and 35-355 MP/L were measured in bark and biochar effluents, respectively, with >91% of the MP counts consisting of small-sized (25 μm) polyamide spherical particles. Combining all data, a decrease in average MP concentration was noticed with longer filters, likely attributed to channeling in a 25 and 50-cm filter. The analyses of MPs in the bark media revealed that most MPs were retained in the 0-10 cm segment but that some MPs were transported further, with 19% of polyamide retained in the 80-90 cm segment. Overall, this study shows promising results for bark and biochar filters to retain MPs, while highlighting the importance of systematic packing of filters to reduce MP emissions to the environment from polluted stormwater.

The triple exposure nexus of microplastic particles, plastic-associated chemicals, and environmental pollutants from a human health perspective

The presence of microplastics (MPs) is increasing at a dramatic rate globally, posing risks for exposure and subsequent potential adverse effects on human health. Apart from being physical objects, MP particles contain thousands of plastic-associated chemicals (i.e., monomers, chemical additives, and non-intentionally added substances) captured within the polymer matrix. These chemicals are often migrating from MPs and can be found in various environmental matrices and human food chains; increasing the risks for exposure and health effects. In addition to the physical and chemical attributes of MPs, plastic surfaces effectively bind exogenous chemicals, including environmental pollutants (e.g., heavy metals, persistent organic pollutants). Therefore, MPs can act as vectors of environmental pollution across air, drinking water, and food, further amplifying health risks posed by MP exposure. Critically, fragmentation of plastics in the environment increases the risk for interactions with cells, increases the presence of available surfaces to leach plastic-associated chemicals, and adsorb and transfer environmental pollutants. Hence, this review proposes the so-called triple exposure nexus approach to comprehensively map existing knowledge on interconnected health effects of MP particles, plastic-associated chemicals, and environmental pollutants. Based on the available data, there is a large knowledge gap in regard to the interactions and cumulative health effects of the triple exposure nexus. Each component of the triple nexus is known to induce genotoxicity, inflammation, and endocrine disruption, but knowledge about long-term and inter-individual health effects is lacking. Furthermore, MPs are not readily excreted from organisms after ingestion and they have been found accumulated in human blood, cardiac tissue, placenta, etc. Even though the number of studies on MPs-associated health impacts is increasing rapidly, this review underscores that there is a pressing necessity to achieve an integrated assessment of MPs' effects on human health in order to address existing and future knowledge gaps.

Environmental condition-dependent effects of aquatic humic substances on the distribution of phenanthrene in microplastic-contaminated aquatic systems

Numerous studies have focused on the interaction between microplastics (MPs) and phenanthrene (PHE) in aquatic environments. However, the intricate roles of aquatic humic substances (HS), which vary with environmental conditions, in influencing PHE-MP interactions are not yet fully understood. This study investigates the variable and environmentally sensitive roles of HS in modifying the interactions between PHE and polyethylene (PE) MPs under laboratory-simulated aquatic conditions with varying solution chemistry, including pH, HS types, HS concentrations, and ionic strength. Our findings show that the presence of HS significantly reduces the adsorption of PHE onto both pristine and aged PE MPs, with a more pronounced reduction observed in aged PEs. This effect is highlighted by a notable decrease in the partitioning coefficient (Kd) of PHE, which falls from 2.60 × 104 to 1.30 × 104 L/kg on MPs in the presence of HS. The study also demonstrates that alterations in the net charge of HS solutions are crucial in modifying PHE distribution onto PEs. An initial decrease in Kd values at higher pH levels is reversed when HS is introduced. Furthermore, an increase in HS concentrations is associated with lower Kd values. In conditions of higher ionic strength, the retention of PHE by HS is intensified, likely due to an enhanced salting-out effect. This research highlights the significant role of aquatic HS in modulating the distribution of PHE in MP-polluted waters, which is highly influenced by various solution chemistry factors. The findings are vital for understanding the fate of PHE in MP-contaminated aquatic environments and can contribute to refining predictive models that consider diverse solution chemistry scenarios.

Effects of polyethylene microplastics occurrence on estrogens degradation in soil

Growing focus has been drawn to the continuous detection of high estrogens levels in the soil environment. Additionally, microplastics (MPs) are also of growing concern worldwide, which may affect the environmental behavior of estrogens. However, little is known about effects of MPs occurrence on estrogens degradation in soil. In this study, polyethylene microplastics (PE-MPs) were chosen to examine the influence on six common estrogens (estrone (E1), 17α-estradiol (17α-E2), 17β-estradiol (17β-E2), estriol (E3), diethylstilbestrol (DES), and 17α-ethinylestradiol (17α-EE2)) degradation. The results indicated that PE-MPs had little effect on the degradation of E3 and DES, and slightly affected the degradation of 17α-E2, however, significantly inhibited the degradation of E1, 17α-EE2, and 17β-E2. It was explained that (i) obvious oxidation reaction occurred on the surface of PE-MPs, indicating that PE-MPs might compete with estrogens for oxidation sites, such as redox and biological oxidation; (ii) PE-MPs significantly changed the bacterial community in soil, resulting in a decline in the abundance of some bacterial communities that biodegraded estrogens. Moreover, the rough surface of PE-MPs facilitated the estrogen-degrading bacterial species (especially for E1, E2, and EE2) to adhere, which decreased their reaction to estrogens. These findings are expected to deepen the understanding of the environmental behavior of typical estrogens in the coexisting system of MPs.

Ecotoxicological evaluation of surface waters in Northern Namibia

The increasing pressure on freshwater systems due to intensive anthropogenic use is a big challenge in central-northern Namibia and its catchment areas, the Kunene and the Kavango Rivers, and the Cuvelai-Etosha Basin, that provide water for more than 1 million people. So far, there is no comprehensive knowledge about the ecological status and only few knowledge about the water quality. Therefore, it is crucial to learn about the state of the ecosystem and the ecological effects of pollutants to ensure the safe use of these resources. The surface waters of the three systems were sampled, and three bioassays were applied on three trophic levels: algae, daphnia, and zebrafish embryos. Additionally, in vitro assays were performed to analyze mutagenicity (Ames fluctuation), dioxin-like potential (micro-EROD), and estrogenicity (YES) by mechanism-specific effects. The results show that acute toxicity to fish embryos and daphnia has mainly been detected at all sites in the three catchment areas. The systems differ significantly from each other, with the sites in the Iishana system showing the highest acute toxicity. At the cellular level, only weak effects were identified, although these were stronger in the Iishana system than in the two perennial systems. Algae growth was not inhibited, and no cytotoxic effects could be detected in any of the samples. Mutagenic effects and an estrogenic potential were detected at three sites in the Iishana system. These findings are critical in water resource management as the effects can adversely impact the health of aquatic ecosystems and the organisms within them.

Are you drowned in microplastic pollution? A brief insight on the current knowledge for early career researchers developing novel remediation strategies

Microplastics (MPs) composed of different polymers with various shapes, within a vast granulometric distribution (1 μm - 5 mm) and with a wide variety of physicochemical surface and bulk characteristics spiral around the globe, with different atmospheric, oceanic, cryospheric, and terrestrial residence times, while interacting with other pollutants and biota. The challenges of microplastic pollution are related to the complex relationships between the microplastic generation mechanisms (physical, chemical, and biological), their physicochemical properties, their interactions with other pollutants and microorganisms, the changes in their properties with aging, and their small sizes that facilitate their diffusion and transportation between the air, water, land, and biota, thereby promoting their ubiquity. Early career researchers (ERCs) constitute an essential part of the scientific community committed to overcoming the challenges of microplastic pollution with their new ideas and innovative scientific perspectives for the development of remediation technologies. However, because of the enormous amount of scientific information available, it may be difficult for ERCs to determine the complexity of this environmental issue. This mini-review aims to provide a quick and updated overview of the essential insights of microplastic pollution to ERCs to help them acquire the background needed to develop highly innovative physical, chemical, and biological remediation technologies, as well as valorization proposals and environmental education and awareness campaigns. Moreover, the recommendations for the development of holistic microplastic pollution remediation strategies presented here can help ERCs propose technologies considering the environmental, social, and practical dimensions of microplastic pollution while fulfilling the current government policies to manage this plastic waste.

Organic pollutants adsorbed on microplastics: Potential indicators for source appointment of microplastics

Pollution by microplastics (MPs) has caused potential threats to the environment. Understanding the sources of MPs in the environment can help control their emissions and reduce environmental risks. Source apportionment of MPs has been conducted according to the characteristics of MPs themselves (such as types of polymers and morphological characteristics). However, the specificity and resolution of the appointments of sources need to be improved. Organic pollutants adsorbed on MPs can be used as a novel and reliable indicator to identify the source of MPs in the environment. In the present work, the analytical methods of MPs and organic pollutants adsorbed on MPs were critically reviewed, and the occurrence of organic pollutants and factors influencing their adsorption on MPs were discussed. Furthermore, the potential applications of organic pollutants adsorbed on MPs as indicators for determining the sources of MPs were highlighted. The study would help recognize the sources of MPs, which will support efforts aimed at reducing their emissions and further pollution of the ecosystem.

Insights into the effect of hydrochar-derived dissolved organic matter on the sorption of diethyl phthalate onto soil: A pilot mechanism study

Biowaste-derived hydrochar is an emerging close-to-natural product and has shown promise for soil improvement and remediation, but the environmental behavior of the dissolved organic matter released from hydrochar (HDOM) is poorly understood. Focusing on the typical mulch film plasticizer diethyl phthalate (DEP), we investigated the effect of HDOM on the sorption behavior of DEP on soil. The relatively low concentration of HDOM (10 mg L-1, 25 mg L-1) decreases the sorption quantity of DEP on soil, while it increases by a relatively high concentration, 50 mg L-1. The transformation from multilayer to monolayer sorption of DEP on soil occurs as the concentration of HDOM increases. The tryptophan-like substance is the main component of HDOM sorbed to soil, reaching 49.82 %, and results in competition sorption with DEP. The soil pores are blocked by HDOM, which limits the pore filling and mass transfer of DEP, but partitioning is significantly enhanced. The surface functional groups in HDOM are similar to those in soil, and chemical sorption, mainly composed of hydrogen bonding, exists but is not significantly strengthened. We identified the specific impact of HDOM on the sorption of organic pollutants on soil and provide new insights into the understanding of the environmental behavior of hydrochar.

The seasonality of the concentration of endocrine phenolic compounds in the matter attached to the surface of microplastics

Rapid biofilm formation on microplastic (MP) surfaces in marine environments and the tendency of hydrophobic pollutants to bioaccumulate may increase the exposure of organisms to ingested plastics and transport pollutants far from their sources. The role of the matter attached to MPs (MaM) in the interactions between MPs and other pollutants in marine environments is poorly understood. This paper studies pollutant sorption in MaM for three phenolic endocrine-disrupting chemicals (EDCs): bisphenol A (BPA), 4-tert-octylphenol (4-t-OP), and 4-nonylphenol (4-NP). Polypropylene (PP), expanded polystyrene (EPS), and polylactide (PLA) MPs were exposed to an environment conducive to biofouling (Vistula Lagoon, Baltic Sea) for four weeks in summer, spring, and winter. The concentrations of EDCs in MaM and the suspended particulate matter (SPM) were similar and were 2-3 orders of magnitude higher than those in water and sediment. The type and morphology of the polymers were less significant for determining the concentrations of EDCs in MaM than the season. The concentrations were higher in the growing season than in winter. EDCs increased linearly with the increase in particulate organic carbon. The relationships between organic carbon partition coefficients and octanol/water partition coefficients indicate that hydrophobic partitioning into organic matter was the dominant mechanism of 4-t-OP and 4-NP binding in MaM and in SPM. For BPA, additional sorption mechanisms seem to be significant. In addition to the direct sorption from ambient water, the binding of phytoplankton-derived particles, most probably via attachment to extracellular polymeric substances, appears to be a source of EDCs in MPs. Rough estimates showed that the largest load of particulate matter and EDCs was attached to expanded polystyrene. This study suggests that the potential negative impacts of MPs on the environment are seasonal and that low-density porous plastics can be particularly effective carriers of large EDC loads.

Adsorption of As(III) by microplastics coexisting with antibiotics

Although recent studies have been conducted on the pollution and toxicity of microplastics with heavy metals or antibiotics, it is necessary to further investigate the coexistence of antibiotics and heavy metals on the surface of microplastics. In this study, the mechanisms of As(III) adsorption by polystyrene (PS) and polyamide (PA) microplastics in the presence of antibiotics (ciprofloxacin, CIP) were investigated. Adsorption behavior was investigated using kinetic and isotherm models, and the effects of microplastic particle size, aging, ion concentration, pH, xanthic acid (FA), and tannic acid (TA) were considered. Adsorption kinetics and isotherm models showed that the kinetics of As(III) adsorption on PS were consistent with a pseudo-first-order model; the kinetics of adsorption on PA were more consistent with segmented linear regression. The Freundlich model is consistent with the adsorption isotherms of As(III) on PS and PA. The smaller the microplastic particle size and the longer the aging time, the better the adsorption of As(III). Increasing NO3-significantly inhibited the adsorption of As(III) by PS, while it first promoted and then inhibited the adsorption by PA. The effect of pH was similar to that ofNO3-. The adsorption of As(III) by PS was significantly promoted by FA and TA, regardless of the presence of CIP; the adsorption of As(III) by PA was inhibited. Scanning electron microscopy (SEM) was used to characterize microscopic morphology of pristine and aged PS and PA microplastics; Fourier transform infrared (FTIR) and X-ray absorption spectroscopy (XPS) revealed changes in surface functional groups of PS and PA, while demonstrating the importance of different functional groups in exogenous additives (CIP and dissolved organic matter, DOM) in the adsorption of As(III). This study provides new insight into adsorption behaviors and interaction mechanisms between ternary pollutants.

Adsorption behavior of triclosan on polystyrene nanoplastics: The roles of particle size, surface functionalization, and environmental factors

Nanoplastics (NPs) contribute substantially to the transport of waterborne pollutants. Triclosan (TCS) has a high potential to contact with NPs because of their prevalence in natural waters. Herein, this study investigated the adsorption behavior of TCS on differently sized and functionalized polystyrene (PS) NPs. The effects of environmental factors such as pH, salinity, and dissolved organic matter (DOM) were also evaluated. Results suggest that the adsorption equilibrium constant (kd) of TCS in pristine PSNP suspensions followed the order as: PSNPs-50 nm (4.39 L·g-1) > PSNPs-100 nm (2.78 L·g-1) > PSNPs-200 nm (2.59 L·g-1) > PSNPs-500 nm (1.36 L·g-1) ≈ PSNPs-900 nm (1.36 L·g-1). For the functionalized PSNPs (i.e., PSNPs-COOH, PSNPs-NH2), the values of specific surface area normalized kd called kd, SSA were higher than those of pristine PSNPs. Meanwhile, TCS adsorption on two functionalized PSNPs remained stable and then decreased as salinity increased, while an opposite trend was observed toward pristine PSNPs. All these suggested that physicochemical properties of PSNPs (e.g., particle size and surface functional groups) are important factors influencing their adsorption capacity. When the solution pH raised, the adsorbed amounts of TCS on all tested PSNPs prone to decline. However, DOM only affected the adsorption behavior of PSNPs-50 nm, probably owing to its aggregation with tiny PSNPs and the induced secondary adsorption.

Sulfate radical-based advanced oxidation process effects on tire wear particles aging and ecotoxicity

Tire wear particles (TWPs) are widely distributed in natural water and pose as major pollutants in aquatic environments. In this study, heat-activated persulfate (HPT) and ultraviolet-activated persulfate treatments (UPT) were employed to investigate the influence of sulfate radical (SO4-•)-based advanced oxidation process (SAOPs) on TWP physicochemical properties and to clarify their ecotoxic effects in laboratory-level studies. Results showed that the specific surface areas of TWPs increased after UPT but decreased after HPT. In terms of chemical properties, the increase of oxygen-containing functional groups on the surfaces of TWPs was more evident in UPT than that in HPT. The atrazine (ATZ) adsorption capacity of TWPs after HPT and UPT was increased compared with the untreated TWPs. Atrazine adsorbed by TWPs was easily resolved and released in artificial intestinal fluid (1.89-2.08 mg/g) and artificial gastric fluid (1.60-2.04 mg/g) conditions. Acute toxicity experiments of Photobacterium phosphoreum and SEM-EDS detection results suggested that various heavy metals (e.g., Zn2+, Cu2+) in the TWPs would be released into the water system in SAOPs. ATZ released from TWPs that adsorbed ATZ herbicide, rather than TWPs themselves, had a negative effect on aquatic plant growth (e.g., C. vulgaris). The leaching solution of oxidized TWPs (after HPT and UPT) showed a more significant inhibition effect on the zebrafish survival compared with that of untreated TWPs, which was possibly caused by the generation of oxidation byproducts such as N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine-quinone.

Leaching of chemicals from microplastics: A review of chemical types, leaching mechanisms and influencing factors

It is widely known that microplastics are present everywhere and they pose certain risks to the ecosystem and humans which are partly attributed to the leaching of additives and chemicals from them. However, the leaching mechanisms remain insufficiently understood. This review paper aims to comprehensively and critically illustrate the leaching mechanisms in biotic and abiotic environments. It analyzes and synthesizes the factors influencing the leaching processes. It achieves the aims by reviewing >165 relevant scholarly papers published mainly in the past 10 years. According to this review, flame retardants, plasticizers and antioxidants are the three main groups of additives in microplastics with the potentials to disrupt endocrine functions, reproduction, brain development and kidney functions. Upon ingestion, the MPs are exposed to digestive fluids containing enzymes and acids which facilitate their degradation and leaching of chemicals. Fats and oils in the digestive tracts also aid the leaching and transport of these chemicals particularly the fat-soluble ones. Leaching is highly variable depending on chemical properties and bisphenols leach to a larger extent than other endocrine disrupting chemicals. However, the rates of leaching remain poorly understood, owing probably to multiple factors at play. Diffusion and partitioning are two main mechanisms of leaching in biotic and abiotic environments. Photodegradation is more predominant in the latter, generating reactive oxygen species which cause microplastic aging and leaching with minimal destruction of the chemicals leached. Effects of microplastic sizes on leaching are governed by Sherwood number, thickness of aqueous boundary layer and desorption half-life. This review contributes to better understanding of leaching of chemicals from microplastics which affect their ecotoxicities and human toxicity.

Effects of the adsorption behavior of polyamide microplastics on male reproductive health by reduction of testosterone bioavailability

Microplastics (MPs) are global environmental pollutants with potential toxicity concerns, and their effects on the reproductive system have attracted increasing attention. This study investigated the interaction between MPs and mammalian biomolecules, focusing on the relationship between the testosterone adsorption behavior of MPs and male reproductive health. The adsorption capacity of different types of MPs for testosterone was evaluated in vitro experiments. Polyamide (PA)-MPs exhibited stronger adsorption, while polymethyl methacrylate (PMMA)-MPs displayed the weakest adsorption. Sorption equilibrium between PA-MPs and testosterone was achieved within 6 h, fitting the Pseudo-2nd-order model and Langmuir isotherm. The effects of MPs on male reproduction in mice was determined in vivo experiments. Male mice were treated with 0.1 and 0.5 mg/d PA-MPs/PMMA-MPs by gavage once per day for 28 days. The results showed that only 0.5 mg/d PA-MP exposure induced decreased serum testosterone levels, increased testicular testosterone levels compared to the control, and more severe damage to seminiferous tubule structure, sperm motility and sperm morphology compared to the PMMA-MPs group. Meanwhile, PA-MPs could reduce intracellular nuclear translocation of androgen receptor (AR) mediated by testosterone, while PMMA-MPs had no impact. The study revealed that PA-MP adsorption reduced testosterone bioavailability and caused sperm quality to decline, offering new insights into the combined toxicity mechanism of MPs in male mammals.

Microplastics as an emerging contaminant of concern to our environment: a brief overview of the sources and implications

Over the years, it has become evident that microplastics are one of the most important contaminants of concern requiring significant attention. The large abundance of microplastics that are currently in the environment poses potential toxicity risks to all organisms that are exposed to them. Microplastics have been found to affect the physiological and biological processes in marine and terrestrial organisms. As well as being a contaminant of concern in itself, microplastics also have the ability to act as vectors for other contaminants. The potential for microplastics to carry pollutants and transfer them to other organisms has been documented in the literature. Microplastics have also been linked to hosting antibiotic resistant bacteria and antibiotic resistance genes which poses a significant risk to the current health system. There has been a significant increase in research published surrounding the topic of microplastics over the last 5 years. As such, it is difficult to determine and find up to date and relevant information. This overview paper aims to provide a snapshot of the current and emerging sources of microplastics, how microplastics can act as a contaminant and have toxic effects on a range of organisms and also be a vector for a large variety of other contaminants of concern. The aim of this paper is to act as a tool for future research to reference relevant and recent literature in this field.

Exploring the combined interplays: Effects of cypermethrin and microplastic exposure on the survival and antioxidant physiology of Astacus leptodactylus

Plastic waste and micro/nanoplastic particles pose a significant global environmental challenge, along with concerns surrounding certain pesticides' impact on aquatic organisms. This study investigated the effects of microplastic particles (MPPs) and cypermethrin (CYP) on crayfish, focusing on biochemical indices, lipid peroxidation, oxidative stress, hematological changes, and histopathological damage. After determining the LC50-96 h value (4.162 μg/L), crayfish were exposed to sub-lethal concentrations of CYP (1.00 ppb (20%) and 2.00 ppb (50%)) and fed a diet containing 100 mg/kg MPPs for 60 days. Hemolymph transfusion and histopathological examinations of the hepatopancreas were conducted. The results showed significant alterations in crayfish. Total protein levels decreased, indicating protein breakdown to counteract contaminants, while total cholesterol and triglyceride levels declined, suggesting impaired metabolism. Glucose levels increased in response to chemical stress. The decline in total antioxidant capacity highlighted the impact of prolonged xenobiotic exposure and oxidative stress, while increased CAT, SOD, and MDA activities helped mitigate oxidative stress and maintain cellular homeostasis. The elevated total hemocyte count, particularly in semi-granular cells, suggests their active involvement in the detoxification process. Further research is needed to fully understand the implications of these effects.

Selective enrichments for color microplastics loading of marine lipophilic phycotoxins

Microplastics (MPs) and marine lipophilic phycotoxins (MLPs) are two classes of emerging contaminants. Together, they may exacerbate the negative impacts on nearshore marine ecosystems. Herein, the loading of 14 representative MLPs, closely related to toxin-producing algae, on MPs and their relations with colorful MPs have been explored for the first time based on both field and lab data. The objectives of our study are to explore the roles of multiple factors (waterborne MLPs and MP characteristics) in the loading of MLPs by MPs with the applications of various statistical means, and to further explore the role of the color of MP in the loading of specific MLPs through lab simulation experiments. Our results demonstrated that MPs color determined the loading of some specific MLPs on MPs and green MPs can load much more than other colorful fractions (p < 0.05). These interesting phenomena illustrated that the color effects on the loading processes of MLPs on MPs are a dynamic process, and it can be well explained by the shading effect of MP color, which may affect the growth and metabolism of the attached toxic-producing algae on MPs and hence the production of specific MLPs. Furthermore, loading of MLPs on MPs can be considered as the comprehensive physicochemical and biological processes. Our results caution us that special attention should be paid to explore the real-time dynamic color shading effects on all kinds of bio-secreted contaminants loading on MPs, and highlight the necessary to comprehensive investigate the interaction between biota, organic contaminants and MPs.

Bis(2-ethylhexyl) phthalate transfer from polyvinyl chloride sheet to several kinds of particles

Bis(2-ethylhexyl) phthalate (DEHP) transfer from a polyvinyl chloride (PVC) sheet to 9 kinds of particles, namely, polyethylene particles (1-10, 45-53, 90-106 μm), soda lime glass particles (1-38, 45-53, 90-106 μm), black forest soil, carbon black, and cotton linter, for the particle weights of 0.3, 1, 3, and 12 mg/cm2, were determined for 1, 3, 7, and 14 days using a passive flux sampler (PFS), as well as standard dust. Transfer amounts to small polyethylene particles (1-10 μm), black forest soil, and carbon black were large (8.5, 16, and 48 μg/mg-particle, respectively, for 0.3 mg/cm2 for 14 days) and were similar to standard house dust (35 μg/mg-particle). On the other hand, transfer amount to large polyethylene particles (0.056-0.12 μg/mg-particle), soda lime glass (0.18-0.31 μg/mg-particle), and cotton linter (0.42-0.78 μg/mg-particle) were much lower. The DEHP transfer amount to the particles was proportional to the surface area of the particles, but not associated with the organic content. The DEHP transfer amount per surface area to small polyethylene particles was larger than that of other particles, suggesting the contribution of absorption into the polyethylene particle. However, for the larger polyethylene particles with different manufacturing process that may have different crystallinity, the contribution of absorption was small. The amount of DEHP transferred to soda lime glass did not differ from 1 to 14 days, suggesting that an adsorption equilibrium was reached after 1 day. The estimated value of particle/gas partition coefficients of DEHP, Kpg, of small polyethylene, black forest soil and carbon black were much higher (3.6, 7.1, and 18 m3/mg, respectively) than those of large polyethylene and soda lime glass particles (0.028-0.11 m3/mg).

Toxicity of microplastics and nanoplastics: invisible killers of female fertility and offspring health

Microplastics (MPs) and nanoplastics (NPs) are emergent pollutants, which have sparked widespread concern. They can infiltrate the body via ingestion, inhalation, and cutaneous contact. As such, there is a general worry that MPs/NPs may have an impact on human health in addition to the environmental issues they engender. The threat of MPs/NPs to the liver, gastrointestinal system, and inflammatory levels have been thoroughly documented in the previous research. With the detection of MPs/NPs in fetal compartment and the prevalence of infertility, an increasing number of studies have put an emphasis on their reproductive toxicity in female. Moreover, MPs/NPs have the potential to interact with other contaminants, thus enhancing or diminishing the combined toxicity. This review summarizes the deleterious effects of MPs/NPs and co-exposure with other pollutants on female throughout the reproduction period of various species, spanning from reproductive failure to cross-generational developmental disorders in progenies. Although these impacts may not be directly extrapolated to humans, they do provide a framework for evaluating the potential mechanisms underlying the reproductive toxicity of MPs/NPs.

Laboratory Studies about Microplastic Aging and Its Effects on the Adsorption of Chlorpyrifos

The constant change in microplastics (MP) due to exposure to environmental conditions leads to physical and chemical changes that enhance their ability to transport other pollutants, increasing the concern about their widespread presence in the environment. This work aimed to simulate the aging process of six MP (polyamide 6, unplasticized polyvinyl chloride, low-density polyethylene, polystyrene, polyethylene-co-vinyl acetate, polypropylene) in freshwater and seawater ecosystems at laboratory scale and evaluate its effects through optical microscope observation, Fourier transform infrared spectroscopy-Attenuated Total Reflectance (FTIR-ATR), Raman spectroscopy, and thermal gravimetric analysis (TGA). Through a combined experimental study of aged MP, the degradation by UV interaction was evidenced by the appearance of new infrared bands in the FTIR spectra assigned to ketones and hydroxyl groups. While Raman analysis and microscope images reveal the appearance of pores, wrinkles, and roughness in the MP surfaces. Variations in the temperature of the maximum weight loss of the MP were observed in the TGA analysis. The adsorption of chlorpyrifos (CPF), a common pesticide widely used in agriculture, by the pristine and aged MP was also studied. The highest affinity for CPF was observed for pristine LDPE and the lowest for PP. The batch adsorption studies revealed an increase in adsorption capacity as a consequence of the aging process for both MP. These results proved that the weathering effects caused changes in the behavior of MP, namely in the interaction with other pollutants.

Studies on competitive adsorption characteristics of bisphenol A and 17α-ethinylestradiol on thermoplastic polyurethane by site energy distribution theory

Compound pollution of microplastics and estrogens is a growing ecotoxicological problem in aquatic environments. The adsorption isothermal properties of bisphenol A (BPA) and 17α-ethinyl estradiol (EE2) on polyamide (TPU) in monosolute and bisolute systems were studied. Under the same adsorption concentration (1-4 mg L-1), EE2 had a greater adsorption capacity than BPA in the monsolute system. Compared to the energy distribution features of the adsorption sites of EE2 and BPA, the BPA adsorption sites were located in the higher energy area and were more evenly distributed than those of EE2, while the quantity of BPA adsorption sites was less than that of EE2. In the bisolute system, the average site energy, site energy inhomogeneity, and adsorption site numbers of BPA increased by 1.674, -17.166, and 16.793%, respectively. In comparison, the average site energy, site energy inhomogeneity, and adsorption sites numbers of EE2 increased by 2.267, 4.416, and 8.585%, respectively. The results showed that BPA and EE2 had a cooperative effect on the competitive adsorption of TPU. XPS analysis showed that BPA and EE2 had electron transfer on TPU, although the chemisorption effects and hydrogen bonds between BPA and TPU were more significant. Comparing the changes in the relative functional group content of TPU in monosolute and bisolute systems, BPA and EE2 were synergistically absorbed on TPU. This study can provide a theoretical reference for the study of competitive adsorption between coexisting organic pollutants.

Adsorption behavior of triclosan on microplastics and their combined acute toxicity to D. magna

Microplastics (MP) have been recently identified as emerging water contaminants in worldwide. Owing to its physicochemical properties, MP have been considered as a vector of other micropollutants and may affect their fate and ecological toxicity in the water environment. In this study, triclosan (TCS), which is a widely-used bactericide, and three frequently found types of MP (PS-MP, PE-MP, and PP-MP) were investigated. The adsorption behavior of TCS on MP was investigated by the effect of reaction time, initial concentration of TCS, and other water chemistry factors. Elovich model and Temkin model are the most fitted well with kinetics and adsorption isotherms, respectively. The maximum TCS adsorption capacities were calculated for PS-MP (9.36 mg/g), PP-MP (8.23 mg/g), and PE-MP (6.47 mg/g). PS-MP had higher affinity to TCS owing to hydrophobic and π-π interaction. The TCS adsorption on PS-MP was inhibited by decreasing concentrations of cations, and increasing concentration of anion, pH, and NOM concentration. At pH 10, only 0.22 mg/g of adsorption capacity was obtained because of the isoelectric point (3.75) of PS-MP and pKa (7.9) of TCS. And almost no TCS adsorption occurred at NOM concentration of 11.8 mg/L. Only PS-MP had no acute toxic effect on D. magna, whereas TCS showed acute toxicity (EC_50,24h of TCS = 0.36 ± 0.4 mg/L). Although survival rate increased when TCS with PS-MP due to lower the TCS concentration in solution via adsorption, PS-MP was observed in intestine and body surface of D. magna. Our findings can contribute to understanding the combined potential effects of MP fragment and TCS to aquatic biota.

Response characteristics of indigenous microbial community in polycyclic aromatic hydrocarbons (PAHs) contaminated aquifers under polyethylene microplastics stress: A microcosmic experimental study

To understand the response characteristics of indigenous microbial community in PAH-contaminated aquifers to the coexistence of microplastics. In this paper, we constructed a groundwater microecosystem using lithologic media collected from the field and subjected it to the stress of a polyethylene microplastics (PE-MPs) concentration gradient. By conducting adsorption experiments and 16S rRNA sequencing, we revealed the growth, structure, metabolism, and resistance mechanisms of the indigenous microbial community in the aquifer lithologic media exposed to varying levels of co-stress from PE-MPs and phenanthrene. Our findings suggest that the adsorption capacity of aquifer lithologic media for phenanthrene is significantly weaker than that of PE-MPs. Additionally, our observations indicated that small particle lithologic media had a greater adsorption capacity for phenanthrene than large particle lithologic media. The presence of PE-MPs was found to increase both the abundance and diversity of microbial communities, although the relationship was not linear with the content of PE-MPs. When exposed to the combined stress of PE-MPs and phenanthrene, the relative abundance of Proteobacteria decreased while that of Bacteroidetes increased. Several genera belonging to Proteobacteria (Aeromonas, Desulfovibrio, Klebsiella, Pantoea, and Microvirgula) and Bacteroidetes (Macellibacteroides and Bacteroides) occupied a central position in the microbial community interaction network and showed significant correlations with other genera. Furthermore, an increase in the proportion of genera capable of degrading various refractory organics was observed. The presence of PE-MPs increased the phenanthrene content in the aquifer lithologic media, thereby intensifying the inhibitory effect on indigenous microbial community in this environment. Despite an increase in the phenanthrene content of aquifer lithologic media due to the presence of PE-MPs, indigenous microbial community in this environment exhibited resistance to the combined inhibition of PE-MPs and phenanthrene through a series of resistance mechanisms. These mechanisms included strengthening the N-cycle process, enhancing metabolic capacity for phenanthrene, improving perception, response, and adaptation to changes in the external environment or intracellular state, modifying the transmembrane transport of the cell membrane to the substrate, and regulating life processes.

Microplastics in aquatic environments: A comprehensive review of toxicity, removal, and remediation strategies

The occurrence of microplastics (MPs) in aquatic environments has been a global concern because they are toxic and persistent and may serve as a vector for many legacies and emerging pollutants. MPs are discharged to aquatic environments from different sources, especially from wastewater plants (WWPs), causing severe impacts on aquatic organisms. This study mainly aims to review the Toxicity of MPs along with plastic additives in aquatic organisms at various trophic compartments and available remediation methods/strategies for MPs in aquatic environments. Occurrences of oxidative stress, neurotoxicity, and alterations in enzyme activity, growth, and feeding performance were identical in fish due to MPs toxicity. On the other hand, growth inhibition and ROS formation were observed in most of the microalgae species. In zooplankton, potential impacts were acceleration of premature molting, growth retardation, mortality increase, feeding behaviour, lipid accumulation, and decreased reproduction activity. MPs togather with additive contaminants could also exert some toxicological impacts on polychaete, including neurotoxicity, destabilization of the cytoskeleton, reduced feeding rate, growth, survivability and burrowing ability, weight loss, and high rate of mRNA transcription. Among different chemical and biological treatments for MPs, high removal rates have been reported for coagulation and filtration (>86.5 %), electrocoagulation (>90 %), advanced oxidation process (AOPs) (30 % to 95 %), primary sedimentation/Grit chamber (16.5 % to 58.84 %), adsorption removal technique (>95 %), magnetic filtration (78 % to 93 %), oil film extraction (>95 %), and density separation (95 % to 100 %). However, desirable extraction methods are required for large-scale research in MPs removal from aquatic environments.

Microplastics exacerbate co-occurrence and horizontal transfer of antibiotic resistance genes

Microplastic pollution is a rising environmental issue worldwide. Microplastics can provide a niche for the microbiome, especially for antibiotic-resistant bacteria, which could increase the transmission of antibiotic resistance genes (ARGs). However, the interactions between microplastics and ARGs are still indistinct in environmental settings. Microplastics were found to be significantly correlated with ARGs (p < 0.001), based on the analysis of samples taken from a chicken farm and its surrounding farmlands. Analysis of chicken feces revealed the highest abundance of microplastics (14.9 items/g) and ARGs (6.24 ×10⁸ copies/g), suggesting that chicken farms could be the hotspot for the co-spread of microplastics and ARGs. Conjugative transfer experiments were performed to investigate the effects of microplastic exposure for different concentrations and sizes on the horizontal gene transfer (HGT) of ARGs between bacteria. Results showed that the microplastics significantly enhanced the bacterial conjugative transfer frequency by 1.4-1.7 folds indicating that microplastics could aggravate ARG dissemination in the environment. Potential mechanisms related to the up-regulation of rpoS, ompA, ompC, ompF, trbBp, traF, trfAp, traJ, and down-regulation of korA, korB, and trbA were induced by microplastics. These findings highlighted the co-occurrence of microplastics and ARGs in the agricultural environment and the exacerbation of ARGs' prevalence via rising the HGT derived from microplastics.

Aging, characterization and sorption behavior evaluation of tire wear particles for tetracycline in aquatic environment

Accounting for more than half of the total primary microplastic (MP) emissions, and one-sixth of the total marine MP pollution in China in 2015, tire wear particles (TWP) are inevitable to age and interact with co-existing species, thus pose a potential risk to the surroundings. The impacts of simulated ultraviolet radiation weathering and liquid-phase potassium persulfate oxidation of TWP on the surface physicochemical properties were comparatively explored. The characterization results demonstrated that the content of carbon black, particle size and specific surface area of the aged TWP all decreased, while the changes of the hydrophobicity and polarity were inconsistent. The interfacial interactions with tetracycline (TC) in aqueous were investigated, the well fitted pseudo-second-order kinetics, Dual-mode Langmuir and Scatchard isotherm models indicated the attachment of TC dominated by surface adsorption at lower concentration, and there's a positive synergistic effect among the main sorption domains. Moreover, the results of the influences of co-existing salts and natural organic matter revealed that the potential risks of TWP elevated by the adjacent media in natural compartment. This work provides new insights into the way that TWP interact with contaminants in the real environment.

Sorption of levonorgestrel on polyethylene, polystyrene and polypropylene microplastics

Sorption studies involving microplastics (MPs) are essential to understand the mechanisms implicated in contaminant retention. In this research, a complete study of the sorption behaviour of a hormonal contraceptive -levonorgestrel- in MPs of different composition in two distinct matrices was performed, using high-performance liquid chromatography coupled to a UV detector for the determination of levonorgestrel. Characterization of the studied MPs was achieved by X-ray diffraction and differential scanning calorimetry, and Fourier-transformed infrared spectroscopy. Kinetic and isotherm studies were performed using a batch design under controlled conditions: 500 mg of MPs pellets of 3-5 mm diameter, agitation at 125 rpm, and 30 °C. The comparison of results in ultrapure water and artificial seawater, revealed changes in sorption capacity, and the predominant sorption mechanisms involved. Overall, all studied MPs showed sorption affinity towards levonorgestrel, being low-density polyethylene the one with the highest sorption capacity in ultrapure water and polystyrene in seawater.

Aging of biodegradable-mulch-derived microplastics reduces their sorption capacity of atrazine

Degradable plastics are gradually regarded as alternatives of conventional, synthetic organic polymers to reduce the plastics or microplastics (MPs) pollution; however, the reports upon environmental risk of degradable plastics are still limited. In order to evaluate the potential vector effect of biodegradable MPs on coexisting contaminants, sorption of atrazine onto pristine and ultraviolet-aged (UV) polybutylene adipate co-terephthalate (PBAT) MPs and polybutylene succinate co-terephthalate (PBST) MPs were investigated. The results showed that, UV aging led to more wrinkles and cracks on the surface, increased homogeneous chains proportion, enhanced hydrophobicity, and enlarged crystallinity of both MPs. The sorption kinetics of atrazine to MPs fitted well into pseudo-first-order (R² = 0.809-0.996) and pseudo-second-order (R² = 0.889-0.994) models. In the concentration range of 0.5-25 mg L^-1, the sorption isotherm fitted into linear (R² = 0.967-0.996) and Freundlich model (R² = 0.972-0.997), indicating that the absorption partitioning was the dominant sorption mechanism. The partition coefficient (K_d) of atrazine to PBAT- MPs (40.11-66.01 L kg^-1) was higher than that of PBST- MPs (34.34-57.96 L kg^-1), and the K_d values of both MPs declined for aged MPs. The specific surface area, hydrophobicity, polarity and crystallinity of MPs jointly interpreted the changing sorption capacity of the MPs. In the present study, both aged PBAT- and aged PBST- MPs exhibited lower vector potential to atrazine than pristine MPs, suggesting reduced risk of being a pollutant carrier, which is of great significance for the development of biodegradable plastics.

Revealing the sorption mechanisms of carbamazepine on pristine and aged microplastics with extended DLVO theory

The co-occurrence of microplastics (MPs) and organic contaminants in aquatic environment can complexify their environmental fate via sorption interactions, especially when the properties of MPs can even vary due to the aging effect. Thus, quantitatively clarifying the sorption mechanisms is required to understand their environmental impacts. This study selected popularly occurring carbamazepine (CBZ) and four types of MPs as model systems, including polyethylene, polyvinyl chloride, polyethylene terephthalate and polystyrene in their pristine and aged forms, to investigate the sorption isotherms, kinetics, and desorption. The variation of MPs during the aging process were analyzed with scanning electron microscopy, contact angle, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. It was found that the aging process elevated the sorption capacity and intensified the desorption hysteresis of CBZ on MPs via increasing the surface roughness, decreasing the particle size, and altering the surficial chemistry of all MPs. The extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory was innovatively applied hereby to calculate the interfacial free energies and revealed that the hydrophobic interaction was significantly lessened after aging for all MPs with the slightly enhanced van der Waals interaction. Then the total interfacial free energies were dropped down for all MPs, which resulted in their declined specific sorption capacity. This work reveals the sorption mechanisms of CBZ on pristine and aged MPs with XDLVO and provides a useful reference to study the sorption of other neutral organics onto MPs.

Polyethylene mulch film-derived microplastics enhance the bioaccumulation of atrazine in two earthworm species (Eisenia fetida and Metaphire guillelmi) via carrier effects

Microplastics (MPs) may significantly affect the bioavailability of coexisting pollutants in soil by adsorption-desorption behavior. However, the mechanisms underlying these interaction remain unclear. Herein, the influence of unused polythylene mulch film-derived MPs (MFMPs) and farmland residual polyethylene mulch film-derived MPs (MFMPs-aged) on the adsorption-desorption behavior and bioavailability of atrazine (ATZ) in soil were investigated. The adsorption kinetics and the adsorption isotherms of ATZ on soil, MFMPs, and MFMPs-aged fitted well by the pseudo-second-order model and the Langmuir model, respectively. ATZ were easier to desorb from soil, MFMPs, and MFMPs-aged in the simulated earthworm digestive fluid than that in the CaCl₂ solution. The adsorption and desorption capacities of MFMPs and MFMPs-aged for ATZ were higher than those of soil, especially for MFMPs-aged. The existence of MPs in soil strengthened the adsorption and desorption capacities of ATZ, and the strengthened effects were promoted by the addition amount and aging process of MPs. Moreover, the occurrence of MPs significantly increased the bioaccumulation of ATZ in earthworms, especially for MFMPs-aged. This study deepens the knowledge of the interaction mechanisms of mulch film-derived MPs and pesticide pollution.

New insights into the distribution, potential source and risk of microplastics in Qinghai-Tibet Plateau

Microplastics (MPs) as emerging contaminants have become a major global concern, however, the distribution and origin of MPs in Qinghai-Tibet Plateau (QTP) and their impacts on ecosystem are poorly known. Hence, we systematically evaluated the profile of MPs on the representative metropolitan locations of Lhasa and Huangshui Rivers and the scenic sites of Namco and Qinghai Lake. The average abundance of MPs in the water samples was 7020 items/m³, which was 34 and 52 times higher than those for the sediment (206.7 items/m³) and soil samples (134.7 items/m³), respectively. Huangshui River had the highest levels, followed by Qinghai Lake, Lhasa River and Namco. Human activities rather than altitude and salinity impacted the distribution of MPs in those areas. Besides the consumption of plastic products by locals and tourists, laundry wastewater and exogenous tributary inputs, the unique prayer flag culture also contributed to the MPs emission in QTP. Notably, the stability and fragment of MPs were crucial for their fate. Multiple assessment models were employed to evaluate the risk of MPs. PERI model took MP concentration, background value and toxicity into account, comprehensively describing the risk differences of each site. The large PVC proportion in Qinghai Lake posed the highest risk. Furthermore, concerns should be raised about PVC, PE and PET in Lhasa and Huangshui Rivers, and PC in Namco Lake. Risk quotient suggested that aged MPs in sediments slowly released biotoxic DEHP and should be cleaned up promptly. The findings offer baseline data of MPs in QTP and ecological risks, providing important support for the prioritization of future control measures.

Investigation of interfacial adsorption between microplastics and methylparaben in aqueous solution

Microplastics and parabens are considered to be a global contaminants, especially in the aquatic ecosystem. The interfacial interaction between four types of microplastics including polystyrene, polyethylene, polyethylene terephthalate, and polyvinyl chloride, and methylparaben were investigated in this study. The results showed that molecular layer dominates the adsorption, with the rate significantly affected by both internal diffusion and external diffusion. Among the four types, polystyrene and polyvinyl chloride showed the smallest and biggest adsorption capability, with the values were 0.656 and 1.269 mg g^-1, respectively. For the adsorption capability, smaller particle size and higher pH value possessed positive effects. However, the existence of metal ions could inhibit the adsorption process, except for a weak promotion at low salinity. Physical adsorption effects, such as electrostatic interaction, hydrogen bond formation, and covalent bond formation, had been identified that dominated the adsorption. This finding could be served as a speculative foundation for the further study of the toxicity, migration, and ecological risk assessment of microplastics in aquatic ecosystem.

Adsorption of 2-hydroxynaphthalene, naphthalene, phenanthrene, and pyrene by polyvinyl chloride microplastics in water and their bioaccessibility under in vitro human gastrointestinal system

The interaction of microplastics (MPs) and organic pollutants has recently become a focus of investigation. To understand how microplastic residues affect the migration of organic pollutants, it is necessary to examine the adsorption and desorption behavior of organic pollutants on MPs. In this study, integrated adsorption/desorption experiments and theoretical calculations were used to clarify the adsorption mechanism of 2-hydroxynaphthalene (2-OHN), naphthalene (NAP), phenanthrene (PHE), and pyrene (PYR) by polyvinyl chloride microplastics (PVC-MPs). Based on the phenomenological mathematical models, the rate-limiting step for analyte adsorption onto PVC-MPs was adsorption onto active sites (R² = 0.865-0.995). Except for PHE, analyte adsorption isotherms were well described by the Freundlich model (R² = 0.992-0.998), and adsorption thermodynamics showed that analyte adsorption on PVC-MPs was a spontaneous exothermic process (ΔH⁰ < 0; ΔG⁰ < 0). Based on the order of adsorption efficiency of 2-OHN < NAP < PHE < PYR, which is identical to the competitive adsorption experiment, polycyclic aromatic hydrocarbon (PAH) adsorption on PVC-MPs increased as the aromatic ring number increased and the hydroxyl content decreased. The release of 2-OHN (49 %-52 %) from PVC-MPs into the simulated gastrointestinal environment was greater than that of NAP (5.5 %-5.7 %). Theoretical calculations and adsorption tests indicated that hydrophobic interaction was the primary influence on the adsorption of PAHs and their hydroxylated derivatives by PVC-MPs. These findings improve our understanding of MPs' behavior and dangers as pollutant carriers in the aquatic environment and help us develop recommendations for the pollution control of MPs.

Antibiotic sorption onto microplastics in water: A critical review of the factors, mechanisms and implications

Microplastics as vectors for contaminants in the environment is becoming a topic of public interest. Microplastics have been found to actively adsorb heavy metals, per-fluorinated alkyl substances (PFAS), polychlorinated biphenyls (PCBs), polyaromatic hydrocarbons (PAHs), pharmaceuticals and personal care products (PPCPs) and polybrominated diethers (PBDs) onto their surface. Particular interest in microplastics capacity to adsorb antibiotics needs further attention due to the potential role this interaction plays on antibiotic resistance. Antibiotic sorption experiments have been documented in the literature, but the data has not yet been critically reviewed. This review aims to comprehensively assess the factors that affect antibiotic sorption onto microplastics. It is recognised that the physico- chemical properties of the polymers, the antibiotic chemical properties, and the properties of the solution all play a crucial role in the antibiotic sorption capacity of microplastics. Weathering of microplastics was found to increase the antibiotic sorption capacity by up to 171%. An increase in solution salinity was found to decrease the sorption of antibiotics onto microplastics, in some instances by 100%. pH also has a substantial effect on sorption capacity, illustrating the significance of electrostatic interactions on the sorption of antibiotics onto microplastics. The need for a uniform experimental design when testing antibiotic sorption is highlighted to remove inconsistencies in the data currently presented. Current literature examines the link between antibiotic sorption and antibiotic resistance, however, further studies are still required to fully understand this emerging global crisis.

Adsorption of highly toxic chlorophenylacetonitriles on typical microplastics in aqueous solutions: Kinetics, isotherm, impact factors and mechanism

Microplastics (MPs) widely exist in all kinds of water bodies. The physical and chemical properties of MPs make them easy to become the carrier of pollutants, but the interaction between disinfection by-products (DBPs) and MPs has not been studied yet. In this study, the occurrence of emerging high-toxic chlorophenylacetonitriles (CPANs) in wastewater treatment plant (WWTP) effluents was determined. CPANs ubiquitously existed in WWTP effluents, and the concentration ranged from 88 ± 5 ng/L to 219 ± 16 ng/L. The typical MPs (i.e., polyethylene (PE), polyethylene terephthalate (PET), and polystyrene (PS)) were selected to study their adsorption of CPANs. Adsorption kinetics and isotherm analysis were carried out. The maximum Langmuir adsorption capacities were 8.602 ± 0.849 to 9.833 ± 0.946 μg/g for PE, 13.340 ± 1.055 to 29.405 ± 5.233 μg/g for PET, and 20.537 ± 1.649 to 43.597 ± 1.871 for PS. Dichloro-CPANs had higher adsorption capacity than monochloro-CPANs. After that, the specific surface area, contact angle, FTIR spectrum, crystallinity, and glass transition temperature (Tg) of MPs were measured. Based on the analysis of the properties of both MPs and CPANs, the mechanism of adsorption was studied. The adsorption of CPANs on PE was mainly affected by pore-filling and van der Waals force. In addition to these two factors, the adsorption of PET was also affected by hydrophobic interaction. Due to the substituents on the benzene ring, there was π-π interaction between PS and CPANs, which might be the reason why PS had the highest adsorption capacity for CPANs. Finally, the effects of pH and dissolved organic matter were studied, and their effects were relatively limited. The results indicated that MPs may adsorb CPANs in actual WWTP effluents, and special attention should be paid to the possible impacts on the aquatic environment caused by the transfer of CPANs on MPs.

Effect of aging on polyethylene microfiber surface properties and its consequence on adsorption characteristics of 17alpha-ethynylestradiol

This study assessed the interactive changes to the endocrine disruptor 17 alpha-ethynylestradiol (EE2) triggered by photoaging onto fibrous microplastics frequently found in the environment. The physicochemical property change of the polyethylene (PE) microfiber according to irradiation (i.e. 14 d UV-C (254 nm)) was studied through Fourier transform infrared spectroscopy, scanning electron microscope, and contact angle analysis. Additionally, the EE2 adsorption kinetics experiment was performed for the PE microfiber before and after UV irradiation to assess the change in adsorption characteristics. After UV irradiation, the PE microfiber surface roughness increased, the oxygen-containing functional group (e.g. carbonyl group) increased, and the contact angle (virgin PE: 80.02°, aged PE: 65.13°) decreased. A decrease in the surface hydrophobicity led to a decrease in the adsorption rate of EE2 (virgin PE: k = 0.0105 h-1, aged PE: not calculated). The hydrophobic interaction significantly affects the adsorption behavior of hydrophobic organic pollutants such as EE2 onto MPs, and continuous photo-aging of MPs may cause a new pattern of ecological risk. Therefore, there is a greater necessity for additional research relevant to this issue.

Insights into adsorption mechanisms of nitro polycyclic aromatic hydrocarbons on common microplastic particles: Experimental studies and modeling

Nitro polycyclic aromatic hydrocarbons (NPAHs) and microplastics (MPs) are emerging contaminants that pose a threat to the aquatic ecosystem. Knowledge of the NPAHs and MPs interaction will help the understanding of their fate and risks in natural environment. Here, the adsorption behavior and mechanism of typical NPAHs on microplastics were investigated. The adsorption kinetic and isotherm data showed that the adsorption of NPAHs was controlled by chemical adsorption and hydrophobic partition, because of excellent fit of kinetic and isothermal equations (R² > 0.9). The adsorption capacity (587-744 μg g^-1) was largely dependent on the hydrophobicity of NPAHs. The experiment of environmental factors confirmed the important role of pollutant hydrophobicity, with 1-Npyr of the highest hydrophobicity having the greatest adsorption on MPs (adsorption rate >90%) and less affected by solution pH and ionic strength (changer <5%). In the mixture system, MPs displayed high adsorption capacity for each compound; Interestingly, because compounds with smaller size were easy to occupy the adsorption sites in the pores of MPs, the adsorption of 2-Nflu (724 μg g^-1) was even greater than that of 9-Nant (713 μg g^-1) and 1-Npyr (703 μg g^-1). The model calculation of adsorption also shows that there is surface adsorption and hydrophobic distribution in the adsorption process. The findings provide new insights into the interactions of MPs with organic pollutants in complex environments.

A critical review on the interaction of polymer particles and co-existing contaminants: Adsorption mechanism, exposure factors, effects on plankton species

This review considers the interaction of microplastics (MPs)/nanoplastics (NPs) and co-existing contaminants, including organic contaminants, potentially toxic elements (PTEs), and metal/metal-oxide nanoparticles. Stronger adsorption between plastic particles and co-existing contaminants can either facilitate or prevent more contaminants to enter plankton. The characteristics of MPs/NPs, such as polymer type, size, functional groups, and weathering, affect combined effects. Mixture toxicity is affected by those factors simultaneously and also affected by the type of co-existing contaminants, their concentrations, exposure time, dissolved organic matter, and surfactant. For co-exposure involving organics and metal nanoparticles, marine Skeletonema costatum generally had antagonistic effects, while marine Chlorella pyrenoidosa, Platymonas subcordiformis, and Tetraselmis chuii, showed synergistic effects. For co-exposure involving organics and PTEs, both Chlorella sp. and Microcystis aeruginosa generally demonstrated antagonistic effects. Freshwater Chlorella reinhardtii and Scenedesmus obliquus had synergistic effects for co-exposure involving metal/metal oxide nanoparticles. Zooplankton shows more unpredicted sensitivity towards the complex system. Different co-existing contaminants have different metabolism pathways. Organic contaminants could be biodegraded, which may enhance or alleviate mixture toxicity. PTEs could be adsorbed and desorbed under changing environments, and further affect the combined effects. The presence of metal/metal-oxide nanoparticles is more complicated, since some may release ion metals, increasing contaminant composition.

The interaction mechanism of polystyrene microplastics with pharmaceuticals and personal care products

Microplastics (MPs) have been detected in the hydrosphere, with hazardous implications in transporting coexisting water pollutants. Our knowledge about the interaction mechanisms that MPs establish with organic pollutants are still growing, which is essential to understand the adsorption properties of MPs and their relative stability with adsorbates. Here, we used classical (force field methods) and ab-initio (density functional theory) computational chemistry tools to characterize the interaction mechanisms between Polystyrene-MPs (PS-MPs) and pharmaceuticals/personal care products (PPCPs). Adsorption conformations and energies, thermochemistry, binding, and energy decomposition analyses were performed to obtain the quantitative mechanistic information. Our results show that PS-MPs have permanent dipoles, increasing the interaction with neutral PPCPs while repelling the charged pollutants; in all cases, a stable physisorption takes place. Moreover, PS-MPs increase their solubility upon pollutant adsorption due to an increase in the dipole moment, increasing their co-transport ability in aqueous environments. The stability of the PS-MPs/PPCPs complexes is further confirmed by thermochemical and molecular dynamics trajectory analysis as a function of temperature and pressure. The interaction mechanism of high pKa pollutants (pKa > 5) is due to a balanced contribution of electrostatic and dispersion forces, while the adsorption of low pKa pollutants (pKa < 5) maximizes the electrostatic forces, and steric repulsion effects explain their relative lower adsorption stability. In this regard, several pairwise intermolecular interactions are recognized as a source of stabilization in the PS-MPs/PPCPs binding: hydrogen bonding, π-π, OH⋯π, and CH⋯π, CCl⋯CH and CH⋯CH interactions. The ionic strength in solution slightly affects the adsorption stability of neutral PPCPs, while the sorption of charged pollutants is enhanced. This mechanistic information provides quantitative data for a better understanding of the interactions between organic pollutants and MPs, serving as valuable information for sorption/kinetic studies.

Mechanistic insights into the adsorption of endocrine disruptors onto polystyrene microplastics in water

Microplastics and endocrine disruptors (EDs) are contaminants of emerging concerns and ubiquitously present in aquatic ecosystems, establishing interactions that still are the subject of investigation due to their implications in the cotransport of pollutants. Then, we conducted mechanistic studies based on state-of-art computational chemistry methods to quantitatively understand the interaction mechanisms whereby polystyrene micro or nanoplastics (PS-MPs) interact with representative classes of EDs in water (Ethynylestradiol, Estradiol, and Bisphenol A). The results showed that PS-MPs increase their charge distribution when forming microparticles in water, giving a permanent dipole that explains their increasing solubility in aqueous conditions. In agreement with experimental assessments, the PS-MPs favorably adsorb EDs with adsorption energies larger than 15 kcal/mol, even with comparable stability to nanostructured materials for adsorption, removal, and/or analysis of pollutants. The adsorption occurs via physisorption without covalent binding, bond breaking, or structural preparation energies, where the molecular structure of EDs can favor inner or outer surface adsorption depending on the molecular structure of the adsorbates. A balanced contribution of dispersion and electrostatic stabilizing effects determines the interaction mechanisms, accounting for a whole contribution of 88-90%. The electrostatic contribution emerges from the favorable alignment of the PS-MPs and EDs dipoles upon interaction due to the mild charge transfer between them in solution. In contrast, the dispersion contribution emerges from electron-electron interactions due to the permanent dipoles in adsorbates and adsorbents. Furthermore, thermochemical analyses clarify the role of temperature and pressure effects on the relative adsorption stability among EDs in aquatic environments. Therefore, modeling the adsorption process contributes to new knowledge on the sorption properties of PS-MPs, providing a mechanistic basis to understand the cotransport of pollutants in water environments and their impacts on environmental pollution.

Assessment of relationship between aging and contaminant-carryover for different filter layer of surgical mask under urban environmental stressors

Abundant disposable surgical masks (SMs) remain in the environment and continue to age under urban environmental stressors. This study aimed to investigate the aging characteristics of SMs and the effect of different aged layers of SMs on phenanthrene (PHE), tylosin (TYL), and sulfamethazine (SMT) under two different urban environmental stressors (UV and ozone). The results show that UV exposure causes more severe aging of the SM layers than ozone. The middle layer, made of melt-brown fabric, has displayed the highest degree of aging due to its smaller diameter and mechanical strength. The two-dimensional correlation spectroscopy (2D-COS) analysis reveals the different aging sequences of functional groups and three layers in aged SMs under the two urban environmental stressors. Whether the SMs are aged or not, the adsorptions of three organic pollutants on SMs are positively correlated with the octanol-water partition coefficient. Furthermore, except for the dominant hydrophobic interaction, aged SMs can promote the adsorption of three organic pollutants by accessory interactions (hydrogen bonding and partition), depending on their structures. These findings highlight the environmental effects of new microplastic (MP) sources and coexisting pollutants under the influence of COVID-19, which is helpful in accurately evaluating the biological toxicity of SMs.

Comparative analysis of the sorption behaviors and mechanisms of amide herbicides on biodegradable and nondegradable microplastics derived from agricultural plastic products

Coexisting of microplastics (MPs) and residual herbicides has received substantial attention due to concerns about the pollutant vector effect. Here, the widely used amide herbicides were examined for their sorption behaviors on the priority biodegradable and nondegradable MPs identified in intensive agriculture. The fitting results indicated that the interactions between napropamide (Nap)/acetochlor (Ace) and the MPs, i.e., poly (butyleneadipate-co-terephthalate) microplastic (PBATM), polyethylene microplastic (PEM), and polypropylene microplastic (PPM), may be dominated by hydrophobic absorptive partitioning on the heterogeneous surfaces. Additionally, chemisorption cannot be ignored for the sorption of Nap/Ace on the biodegradable MPs. The sorption capacities of Nap/Ace on the MPs followed the order of PBATM > PEM > PPM. The differences in sorption capacity which varied by the MP colors were not significant. The hydrophobicity of the herbicides and the MPs, the rubber regions, surface O-functional groups, benzene ring structures and large specific surface area of the biodegradable MPs played key roles in the better performance in sorbing amide herbicides. Moreover, MPs, especially biodegradable MPs, might lead to a higher vector effect for residual amide herbicides than some other common environmental media. This study may provide baseline insights into the great potential of biodegradable MPs to serve as carriers of residual amide herbicides in intensive agrosystems.

Sorption and desorption of bisphenols on commercial plastics and the effect of UV aging

Plastics gradually degrade in the natural environment from the effect of irradiation, which can change the surface properties of plastics and affect the migration behaviour of pollutants. Up to now, studies on the sorption/desorption behaviour of organic pollutants on aged plastics are still limited. In this study, several types of commercial plastics (polyurethane (PU), polyamide (PA), polyvinyl chloride (PVC), expanded polystyrene (EPS)) were selected to investigate the sorption and release behaviour for four kinds of bisphenols (bisphenol-F, A, B, AP). The results from Raman spectroscopy and scanning electron microscopy (SEM) analysis showed evidence of oxidization and surface cracks of plastics after irradiation. The sorption behaviour for both fresh and aged plastics were dominated by hydrophobicity. In addition, the electrostatic force, H-bonding interaction, and π-π interaction were also the important factors impacting the sorption process. The desorption kinetics behaviour indicates that desorption becomes faster after aging. Hydrophobicity is also an important factor that affects desorption behaviour. This study showed that sorption capacity for most fresh and aged plastics was enhanced by the impact of salinity and dissolved organic matter (DOM). Increased temperature could increase the desorption of bisphenols on both fresh and aged plastics, which illustrated that warm environments would promote more pollutants be released from plastics to water bodies.