Sorption of pharmaceuticals over microplastics' surfaces: interaction mechanisms and governing factors

Not for nothing, microplastics can (potentially) reduce the risk of mosquito-to-human transmission of arboviruses

The impact of microplastic pollution has emerged as a significant global ecological concern. Various organisms have exhibited alterations in behavior or metabolic activities following exposure to microplastics (MPs). Mosquitoes, as crucial disease vectors, are particularly susceptible MPs exposure in the environment. Recent studies have demonstrated that MPs ingested by mosquitoes can be detected in vivo, potentially being transmitted during their different life cycles. However, it remains unclear whether MPs in vivo could affect mosquito infection with arboviruses. In this study, we identified that the physical adsorption effect of MPs is also effective against arboviruses, enabling the adsorption of Zika virus particles onto their surfaces. We established an exposure model by feeding adult Aedes albopictus (Skuse, 1895) (Diptera: Culicidae) with 1 μm MPs at concentrations of 5 and 50 μg/mL in 8 % sucrose solution. The transmission rate of ZIKV and population transmission rate in the laboratorial Ae. albopictus exposure model began to decrease from day 7, showing statistically significant differences compared to the control group on days 10 and 14 (**, p < 0.01), significantly affecting their vector efficiency. This phenomenon is not solely dependent on the physical adsorption of MPs to arboviruses. Transcriptome analysis indicated that exposure to MPs influenced the expression levels of genes associated with mosquito virus infection, altering the function of relevant pathways, which consequently reduces their capability to transmit arbovirus. These findings suggest that exposure to MPs significantly affects the vector efficiency of mosquitoes, providing novel perspectives for the ecological risk assessment of MPs.

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.

Surface Water Microplastics in the St. Lawrence River and Estuary in Canada

Microplastics (MPs) are synthetic or semisynthetic polymers that are widely distributed throughout most ecosystems and have the potential to be harmful to living organisms. In this study, we assessed the MP fraction in the top 40 cm of surface water in response to varying salinity levels at 11 distinct sites across the St. Lawrence River and Estuary (SLRE). We employed two sampling nets of different mesh size to collect MPs (100 and 300 µm). These nets were simultaneously towed in parallel from a vessel during three separate sampling events at each designated site. Filtrates collected from these samples underwent analysis of plastic fibers, fragments and spheres utilizing Fourier Transform Infrared Spectroscopy (FTIR). Data unequivocally confirmed the presence of MPs at 100% of the sites sampled within the SLRE. The most abundant categories of MPs identified were the fibers, followed by fragments and spheres. The FTIR analysis revealed the predominant materials to be polyester, polyethylene, polypropylene, nylon, and polystyrene. Notably the findings also suggest MPs are more likely aggregating when salinity increases. This work offers valuable insights into the distribution and behavior of MPs contributing to the preservation and management of water resources.

Sewage treatment plants as a potential source of microplastics in the environment: A preliminary study in Central India

The presence of microplastics in various environmental matrices is a reality. Besides, sewage treatment plants (STPs) play a crucial role in further adding to the microplastic pool of the environment, especially in water and soil resources. As conventional STPs are not primarily meant to remove microplastics, treated effluent and sludge contain a significant amount of microplastic items which are ultimately discharged into the surface water/soil. The present study investigated the role of selected STPs of Central India in contributing microplastics to the environment. Inlet, outlet, and sludge samples were collected from seven STPs and analyzed for the presence of microplastics. Microplastics were found in all samples with higher amounts in the inlet samples (3-35.5 items/L) compared to the outlet samples (2-13.5 items/L). Nevertheless, sludge samples showed the highest amount of microplastics (16-389 items/kg) for all the STPs under study. Size, shape, color, and chemical composition of microplastics was varied with considerable presence of polyethylene, polypropylene, polyethylene-terephthalate, polyvinylchloride, polystyrene, polyamide, polyacrylamide, polyester, and polyurethane. Discharge of these microplastic items in the surface water and terrestrial ecosystems may result in serious consequences for ecology and human health. Therefore, advanced technological development for effective microplastics' removal in STPs is inevitable.

Local and systemic effects of microplastic particles through cell damage, release of chemicals and drugs, dysbiosis, and interference with the absorption of nutrients

Microplastic particles (MPs) have been detected in a variety of environmental samples, including soil, water, food, and air. Cellular studies and animal exposures reported that exposure to MPs composed of different polymers might result in adverse effects at the portal of entry (local) or throughout the body (systemic). The most relevant routes of particle uptake into the body are oral and respiratory exposure. This review describes the various processes that may contribute to the adverse effects of MPs. Only MPs up to 5 µm were found to cross epithelial barriers to a significant extent. However, MPs may also exert a detrimental impact on human health by acting at the epithelial barrier and within the lumen of the orogastrointestinal and respiratory tract. The potential for adverse effects on human health resulting from the leaching, sorption, and desorption of chemicals, as well as the impact of MPs on nutritional status and dysbiosis, are reviewed. In vitro models are suggested as a means of (1) assessing permeation, (2) determining adverse effects on cells of the epithelial barrier, (3) examining influence of digestive fluids on leaching, desorption, and particle properties, and (4) role of microbiota-epithelial cell interactions. The contribution of these mechanisms to human health depends upon exposure levels, which unfortunately have been estimated very differently.

Influence of polystyrene nanoplastics on the toxicity of haloperidol to amphibians: An in vivo and in vitro approach

Chemical pollution is a major driver for the current worldwide crisis of amphibian decline. The present study aimed to assess the influence of polystyrene nanoplastics (PS-NPLs) on the toxicity of haloperidol to aquatic life stages of amphibians, by using in vivo (tadpoles of Xenopus laevis and Pelophylax perezi) and in vitro (A6 and XTC-2 cell lines of X. laevis) biological models. Tadpoles of both species were exposed, for 96 h, to haloperidol: 0.404 to 2.05 mg l-1 (X. laevis) or 0.404 to 3.07 mg L-1 (P. perezi). The most sensitive species to haloperidol (X. laevis) was exposed to haloperidol's LC50,96h combined with two PS-NPLs concentrations (0.01 mg L-1 or 10 mg L-1); the following endpoints were monitored: mortality, malformations, body lengths and weight. In vitro cytotoxicity was assessed by exposing the two cell lines, for 72 h, to: haloperidol (0.195 to 100 mg L-1) alone and combined with 0.01 mg L-1 or 10 mg L-1 of PS-NPLs. Xenopus laevis tadpoles revealed a higher lethal and sublethal sensitivity to haloperidol than those of P. perezi, with LC50,96h of 1.45 and 2.20 mg L-1. In vitro assays revealed that A6 cell line is more sensitive haloperidol than XTC-2: LC50,72h of 13.2 mg L-1 and 5.92 mg L-1, respectively. Results also suggested a higher sensitivity of in vivo models when compared to in vitro biological. Overall, PS-NPLs did not influence haloperidol's toxicity for in vivo and in vitro biological models, except for a reduction on the incidence of malformations while increasing the lethal toxicity (at the lowest concentration) in tadpoles. These opposite interaction patterns highlight the need for a deeper comprehension of NPLs and pharmaceuticals interactions. Results suggest a low risk of haloperidol for anuran tadpoles, though in the presence of PS-NPLs the risk may be increased.

Binding between Cu2+/Zn2+ and aged polyethylene and polyethylene terephthalate microplastics in swine wastewaters: Adsorption behavior, and mechanism insights

Microplastics (MPs) have aroused growing environmental concerns due to their biotoxicity and vital roles in accelerating the spread of toxic elements. Illuminating the interactions between MPs and heavy metals (HMs) is crucial for understanding the transport and fate of HM-loaded MPs in specific environmentally relevant scenarios. Herein, the adsorption of copper (Cu2+) and zinc (Zn2+) ions over polyethylene (PE) and polyethylene terephthalate (PET) particulates before and after heat persulfate oxidation (HPO) treatment was comprehensively evaluated in simulated and real swine wastewaters. The effects of intrinsic properties (i.e., degree of weathering, size, type) of MPs and environmental factors (i.e., pH, ionic strength, and co-occurring species) on adsorption were investigated thoroughly. It was observed that HPO treatment expedites the fragmentation of pristine MPs, and renders MPs with a variety of oxygen-rich functional groups, which are likely to act as new active sites for binding both HMs. The adsorption of both HMs is pH- and ionic strength-dependent at a pH of 4-6. Co-occurring species such as humic acid (HA) and tetracycline (TC) appear to enhance the affinity of both aged MPs for Cu2+ and Zn2+ ions via bridging complexation. However, co-occurring nutrient species (e.g., phosphate and ammonia) demonstrate different impacts on the adsorption, improving uptake of Cu2+ by precipitation while lowering affinity for Zn2+ owing to the formation of soluble zinc-ammonia complex. Spectroscopic analysis indicates that the dominant adsorption mechanism mainly involves electrostatic interactions and surface complexation. These findings provided fundamental insights into the interactions between aged MPs and HMs in swine wastewaters and might be extended to other nutrient-rich wastewaters.

From the highway to receiving water bodies: identification and simultaneous quantification of small microplastics (< 100 µm) in highway stormwater runoff

Highway stormwater (HSW) runoff is among the environment's most important sources of microplastics. This study aimed to characterize via vibrational spectroscopy and quantify SMPs (small microplastics < 100 µm) in HSW runoff from a trafficked highway entering a facility equipped with a filtration system and in those flowing out to the receiving water body near agricultural activities. Samples of the inlet runoff (from the highway) and outlet runoff (the discharge into the environment) were collected in different periods to investigate potential seasonal and spatial differences. The sampling, methodology, and analysis were thoroughly carried out to quantify and simultaneously identify SMPs via Micro-FTIR to obtain a specific novel dataset to assess the environmental quality of highway pollution. A significant difference between inlet and outlet samples was reported; the highest abundance in inlet samples was 39813 ± 277 SMPs L.1 (SW10 IN; average length of 77 µm), while the highest one in outlet samples was 15173 ± 171 SMPs L-1 (SW10 OUT; SMPs' average length of 63 µm). Polyamide 6 (PA 6) and High-Density Polyethylene (HDPE) were predominant. Our results show that these HSW treatment plants, designed for managing regulated pollutants, can intercept SMPs, improving the quality of HSW runoff discharged into the environment.

Combined effect and mechanism of microplastic with different particle sizes and levofloxacin on developing Rana nigromaculata: Insights from thyroid axis regulation and immune system

Microplastics (MPs) usually appear in the aquatic environment as complex pollutants with other environmental pollutants, such as levofloxacin (LVFX). After 45-day exposure to LVFX and MPs with different particle sizes at environmental levels, we measured the weight, snout-to-vent length (SVL), and development stages of Rana nigromaculata. Furthermore, we analyzed proteins and genes related to immune system and thyroid axis regulation, intestinal histological, and bioaccumulation of LVFX and MPs in the intestine and brain to further explore the toxic mechanism of co-exposure. We found MPs exacerbated the effect of LVFX on growth and development, and the order of inhibitory effects is as follows: LVFX-MP3>LVFX-MP1>LVFX-MP2. 0.1 and 1 μm MP could penetrate the blood-brain barrier, interact with LVFX in the brain, and affect growth and development by regulating thyroid axis. Besides, LVFX with MPs caused severer interference on thyroid axis compared with LVFX alone. However, 10 μm MP was prone to accumulating in the intestine, causing severe histopathological changes, interfering with the intestinal immune system and influencing growth and development through immune enzyme activity. Thus, we concluded that MPs could regulate the thyroid axis by interfering with the intestinal immune system.

Occurrence and human risk assessment of pharmaceutically active compounds (PhACs) in indoor dust from homes, schools and offices

This study investigates the current situation and possible health risks due to pharmaceutically active compounds (PhACs) including analgesics, antibiotics, antifungals, anti-inflammatories, psychiatric and cardiovascular drugs, and metabolites, in indoor environments. To achieve this objective, a total of 85 dust samples were collected in 2022 from three different Spanish indoor environments: homes, classrooms, and offices. The analytical method was validated meeting SANTE/2020/12830 and SANTE/12682/2019 performance criteria. All indoor dust samples except one presented at least one PhAC. Although concentration levels ranged from < LOQ to 18 µg/g, only acetaminophen, thiabendazole, clotrimazole, and anhydroerythromycin showed quantification frequencies (Qf %) above 19% with median concentrations of 166 ng/g, 74 ng/g, 25 ng/g and 14 ng/g, respectively. The PhAC distribution between dust deposited on the floor and settled on elevated (> 0.5 m) surfaces was assessed but no significant differences (p > 0.05, Mann-Whitney U-test) were found. However, concentrations quantified at the three types of locations showed significant differences (p < 0.05, Kruskal-Wallis H-test). Homes turned out to be the indoor environment with higher pharmaceutical concentrations, especially acetaminophen (678 ng/g, median). The use of these medicines and their subsequent removal from the body were identified as the main PhAC sources in indoor dust. Relationships between occupant habits, building characteristics, and/or medicine consumption and PhAC concentrations were studied. Finally, on account of concentration differences, estimated daily intakes (EDIs) for inhalation, ingestion and dermal adsorption exposure pathways were calculated for toddlers, adolescents and adults in homes, classrooms and offices separately. Results proved that dust ingestion is the main route of exposure, contributing more than 99% in all indoor environments. Moreover, PhAC intakes for all studied groups, at occupational locations (classrooms and offices) are much lower than that obtained for homes, where hazard indexes (HIs) obtained for acetaminophen (7%-12%) and clotrimazole (4%-7%) at the worst scenario (P95) highlight the need for continuous monitoring.

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.

Surface functionalization, particle size and pharmaceutical co-contaminant dependent impact of nanoplastics on marine crustacean - Artemia salina

Despite a significant amount of research on micronanoplastics (MNPs), there is still a gap in our understanding of their function as transporters of other environmental pollutants (known as the Trojan horse effect) and the combined effects of ingestion, bioaccumulation, and toxicity to organisms. This study examined the individual effects of polystyrene nanoplastics (PSNPs) with various surface functionalizations (plain (PS), carboxylated (PS-COOH), and aminated (PS-NH2)), particle sizes (100 nm and 500 nm), and a pharmaceutical co-contaminant (metformin hydrochloride (MH), an anti-diabetic drug) on the marine crustacean - Artemia salina. The study specifically aimed to determine if MH alters the detrimental effects of PSNPs on A. salina. The potential toxicity of these emerging pollutants was assessed by examining mortality, hatching rate, morphological changes, and biochemical changes. Smaller nanoparticles had a more significant impact than larger ones, and PS-NH2 was more harmful than PS and PS-COOH. Exposure to the nanoparticle complex with MH resulted in a decrease in hatching rate, an increase in mortality, developmental abnormalities, an increase in reactive oxygen species, catalase, and lipid peroxidase, and a decrease in total protein and superoxide dismutase, indicating a synergistic effect. There were no significant differences between the complex and the individual nanoparticles. However, accumulating these particles in organisms could contaminate the food chain. These results highlight the potential environmental risks associated with the simultaneous exposure of aquatic species to plastics, particularly smaller PS, aminated PS, and pharmaceutical complex PS.

Adsorption properties and mechanism of Cu(II) on virgin and aged microplastics in the aquatic environment

Microplastics (MPs) migrate by adsorbing heavy metals in aquatic environments and act as their carriers. However, the aging mechanisms of MPs in the environment and the interactions between MPs and heavy metals in aquatic environments require further study. In this study, two kinds of materials, polyamide (PA) and polylactic acid (PLA) were used as target MPs, and the effects of UV irradiation on the physical and chemical properties of the MPs and the adsorption behavior of Cu(II) were investigated. The results showed that after UV irradiation, pits, folds and pores appeared on the surface of aged MPs, the specific surface area (SSA) increased, the content of oxygen-containing functional groups increased, and the crystallinity decreased. These changes enhanced the adsorption capacity of aged MPs for Cu(II) pollutants. The adsorption behavior of the PA and PLA MPs for Cu(II) conformed to the pseudo-second-order model and Langmuir isotherm model, indicating that the monolayer chemical adsorption was dominant. The maximum amounts of aged PA and PLA reached 1.415 and 1.398 mg/g, respectively, which were 1.59 and 1.76 times of virgin MPs, respectively. The effects of pH and salinity on the adsorption of Cu(II) by the MPs were significant. Moreover, factors such as pH, salinity and dosage had significant effects on the adsorption of Cu(II) by MPs. Oxidative complexation between the oxygen-containing groups of the MPs and Cu(II) is an important adsorption mechanism. These findings reveal that the UV irradiation aging of MPs can enhance the adsorption of Cu(II) and increase their role as pollutant carriers, which is crucial for assessing the ecological risk of MPs and heavy metals coexisting in aquatic environments.

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.

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.

Surface functional groups and biofilm formation on microplastics: Environmental implications

Microplastics (MPs) contamination is becoming a significant environmental issue, as the widespread omnipresence of MPs can cause many adverse consequences for both ecological systems and humans. Contrary to what is commonly thought, the toxicity-inducing MPs are not the original pristine plastics; rather, they are completely transformed through various surface functional groups and aggressive biofilm formation on MPs via aging or weathering processes. Therefore, understanding the impacts of MPs' surface functional groups and biofilm formation on biogeochemical processes, such as environmental fate, transport, and toxicity, is crucial. In this review, we present a comprehensive summary of the distinctive impact that surface functional groups and biofilm formation of MPs have on their significant biogeochemical behavior in various environmental media, as well as their toxicity and biological effects. We place emphasis on the role of surface functional groups and biofilm formation as a means of influencing the biogeochemical processes of MPs. This includes their effects on pollutant fate and element cycling, which in turn impacts the aggregation, transport, and toxicity of MPs. Ultimately, future research studies and tactics are needed to improve our understanding of the biogeochemical processes that are influenced by the surface functional groups and biofilm formation of MPs.

How natural and anthropogenic factors should drive microplastic behavior and fate: The scenario of Brazilian urban freshwater

Brazil maintains its position at the top of the global ranking of plastic producers, yet recycling efforts have been incipient. Recent data reveals an annual production of approximately 14 million tons of plastic waste, not accounting for the surge in the usage of plastic masks and related materials due to the COVID-19 pandemic. However, what remains largely unreported is that over half of post-consumer plastic packaging in Brazil is managed without any monitoring, and it remains unclear how this will contribute to the occurrence of plastic waste and microplastics in Brazilian freshwaters. This scenario requires the consideration of several other crucial factors. Studies have been carried out mainly in marine and estuarine waters, while data on freshwaters are lacking. Brazil has continental dimensions and the highest water availability on the planet, yet the demand for water is greatest in regions with medium to low supply. Many densely populated Brazilian urban areas face chronic flood problems, possess inadequate levels of wastewater treatment, and display inadequate solid waste management practices. Consequently, urban freshwater with tropical characteristics in Brazil presents an intriguing scenario and is complementary to the most commonly studied marine environments. In this study, we explore the nuances of pollution in Brazilian urban freshwater and discuss how various parameters, such as organic matter, suspended solids, temperature, and pH, among others, influence the behavior of microplastics and their interactions with organic and inorganic contaminants. Furthermore, we address how microplastic conditions, such as biofouling, the type of plastic, or degradation level, may impact their behavior. By analyzing how these conditions change, we propose priority themes for investigating the occurrence of microplastics in Brazilian urban freshwater systems under different degrees of human impact. Ultimately, this study aims to establish a network dedicated to standardized monitoring of microplastic pollution in Brazilian urban freshwaters.

Removal efficiencies of microplastics of the three largest drinking water treatment plants in Bangladesh

Drinking water treatment plants (DWTPs) are intended to provide safe water to the municipality, typically by treating surface waters from rivers, lakes, and streams. Regrettably, all of these water sources for DWTPs have been reported to be contaminated by microplastics (MPs). Hence, there is an urgent need to investigate the removal efficiencies of MPs from raw waters in the conventional DWTPs anticipating public health concerns. In this experiment, MPs in the raw and treated waters of the three major DWTPs of Bangladesh, having different water treatment processes, were evaluated. The concentrations of MPs in the inlet points of Saidabad Water Treatment Plant phase-1 and 2 (SWTP-1 and SWTP-2), which share a similar water source of the Shitalakshya River, were 25.7 ± 9.8 and 26.01 ± 9.8 items L-1. The third plant, Padma Water Treatment Plant (PWTP) utilizes water from the Padma River and had an initial MP concentration of 6.2 ± 1.6 items L-1. The studied DWTPs, with their existing treatment processes, were found to reduce the MP loads substantially. The final MP concentrations in treated waters of SWTP-1, SWTP-2, and PWTP were 0.3 ± 0.03, 0.4 ± 0.01, and 0.05 ± 0.02 items L-1 with the removal efficiencies of 98.8, 98.5, and 99.2 %, respectively. The considered size range of MP was 20 μm to <5000. Fragments and fibers were the two predominant MP shapes. In terms of polymer, the MPs were polypropylene (PP, 48 %), polyethylene (PE, 35 %), polyethylene terephthalate (PET, 11 %), and polystyrene (PS, 6 %). The field emission scanning electron microscopy-energy dispersive X-ray spectroscopy (FESEM-EDX) revealed the fractured and rough surfaces of the remaining MPs, which were also found to be contaminated with heavy metals, like lead (Pb), cadmium (Cd), chromium (Cr), arsenic (As), copper (Cu), and zinc (Zn). Hence, additional initiatives are required to remove the residual MPs from the treated waters to safeguard the city dwellers from potential hazards.

Effects of nanoplastics and microplastics on the availability of pharmaceuticals and personal care products in aqueous environment

Nanoplastics (NPs) and microplastics (MPs) could act as potential carriers for pharmaceuticals and personal care products (PPCPs) and alter the bioavailability in the aquatic environment. The effects of NPs and MPs of polystyrene (PS) and polyethylene (PE) on the availability of five PPCPs including carbamazepine, bisphenol A, estrone, triclocarban and 4-tert-octylphenol were investigated by negligible depletion solid- phase microextraction (nd-SPME). The freely dissolved concentrations of PPCPs decreased with the increasing concentrations of NPs/MPs. The overall order of the sorption coefficients (logK_NP / logK_MP) of PPCPs was as follows: 100 nm PS > 50 nm PS > 1 µm PS > 100 µm PS > 100 µm PE. Sorption of PPCPs by NPs was generally 1-2 orders of magnitude stronger than to MPs. The log K_NP / log K_MP values (3.16-5.21) increased with the log K_OW (2.45-5.28) of PPCPs, however, linear correlation was only observed between log K_MP and log K_OW. The particle size, specific surface area, aggregation state as well as hydrophobicity played an important role in the sorption. Coexistence of fulic acid (FA) with NPs inhibited the sorption due to the fouling of FA on NPs. This study suggests that sorption of PPCPs to MPs/NPs could reduce bioavailability of PPCPs in the aquatic environment.

Insights into sorption and molecular transport of atrazine, testosterone, and progesterone onto polyamide microplastics in different aquatic matrices

Microplastics can act as vectors of a wide class of contaminants in aquatic environments. The sorption behavior of two hormones known to cause adverse effects in biota even in low concentrations (testosterone-TTR and progesterone-PGT), and a pesticide with a high environmental persistence known as endocrine disruptor chemical (atrazine-ATZ) onto polyamide (PA) microplastics is investigated under different aquatic matrices using kinetic and isotherm experiments. The sorption equilibrium is achieved in 48 h, and the experimental results are better fitted by pseudo-2nd-order model. Langmuir isotherm better describes the sorption of the contaminants onto PA microplastics. PGT presents the highest sorption efficiency at around 90%, followed by TTR at 70% and ATZ at approximately 20%. Moreover, ATZ is the contaminant with the highest desorption efficiency (∼65%), indicating its preference for staying solubilized in water. Combining classical molecular dynamics and density functional theory calculations, the sorption energies were calculated as 12-15 kcal mol^-1, 13-16 kcal mol^-1, and 19-22 kcal mol^-1 for PGT, TTR, and ATZ, respectively, showing that PGT needs less energy to be transferred from the solvent network to the PA surface, in agreement with experimental results. The sorption mechanism is driven by hydrogen bonds onto PA outer surface, while the electrostatic interactions dominate the PA inner surface sorption. Moreover, the sorption efficiency is statistically different between the investigated matrices, indicating that physicochemical characteristics of water systems could influence the interactions between PA-contaminant. In seawater, the phenomena of salting-out/in and competitive sorption with saline ions are observed for three contaminants. The PA-contaminant complexes are more polar and soluble than the dissociated ones, which increases the contaminant's co-transport by PA in water.

Recent developments in microplastic contaminated water treatment: Progress and prospects of carbon-based two-dimensional materials for membranes separation

Micro (nano)plastics pollution is a noxious menace not only for mankind but also for marine life, as removing microplastics (MPs) is challenging due to their physiochemical properties, composition, and response toward salinity and pH. This review provides a detailed assessment of the MPs pollution in different water types, environmental implications, and corresponding treatment strategies. With the advancement in nanotechnology, mitigation strategies for aqueous pollution are seen, especially due to the fabrication of nanosheets/membranes mostly utilized as a filtration process. Two-dimensional (2D) materials are increasingly used for membranes due to their diverse structure, affinity, cost-effectiveness, and, most importantly, removal efficiency. The popular 2D materials used for membrane-based organic and inorganic pollutants from water mainly include graphene and MXenes however their effectiveness for MPs removal is still in its infancy. Albeit, the available literature asserts a 70- 99% success rate in micro/nano plastics removal achieved through membranes fabricated via graphene oxide (GO), reduced graphene oxide (rGO) and MXene membranes. This review examined existing membrane separation strategies for MPs removal, focusing on the structural properties of 2D materials, composite, and how they adsorb pollutants and underlying physicochemical mechanisms. Since MPs and other contaminants commonly coexist in the natural environment, a brief examination of the response of 2D membranes to MPs removal was also conducted. In addition, the influencing factors regulate MPs removal performance of membranes by impacting their two main operating routes (filtration and adsorption). Finally, significant limitations, research gaps, and future prospects of 2D material-based membranes for effectively removing MPs are also proposed. The conclusion is that the success of 2D material is strongly linked to the types, size of MPs, and characteristics of aqueous media. Future perspectives talk about the problems that need to be solved to get 2D material-based membranes out of the lab and onto the market.

UV and chemical aging alter the adsorption behavior of microplastics for tetracycline

This study evaluates the "vector" effects of different microplastics (MPs) on coexisting pollutants. The adsorption of tetracycline was studied on biodegradable plastics poly(butylene adipate-co-terephthalate) (PBAT) and non-biodegradable plastics polystyrene (PS), polypropylene (PP), and polyethylene (PE) after UV aging and chemical aging. The physicochemical properties of PBAT changed more obviously after UV radiation and chemical aging comparing to PS, PP and PE. Pores and cracks appear on the surface of aged PBAT. The crystallinity increased from 29.2% to 52.62%. In adsorption experiments, pristine and aged PBAT had strong vector effects on the adsorption of tetracycline than PS, PP and PE. The adsorption capacity of tetracycline on PBAT was increased from 0.7980 mg g^-1 to 1.2669 mg g^-1 after chemical aging. The adsorption mechanism indicated that electrostatic interactions and hydrogen bonds contribute to the adsorption process. In addition, for the adsorption of tetracycline on PS, π-π interaction was the main cause, and the adsorption mechanism was not considerably changed by aging. In conclusion, this study demonstrates that biodegradable plastics have substantial vector effect on coexisting pollutants at the end of their life cycle, this contributes to assessment of the risk from microplastic pollution.