Microplastics In Aquatic Environments Research Articles

Photo-aging of brominated epoxy microplastics in water under simulated solar irradiation.

Microplastics have become an increasingly concerning pollutant in aquatic environments, and photodegradation is their main degradation pathway in water. Gaining insight into the transformation process of microplastics will enhance our understanding of their behavior and destiny in natural environments. This paper studied the aging process of BER microplastics in aquatic environments under simulated sunlight and investigated the changes in the physical and chemical properties of microplastics and the changes in the leachate. During the photodegradation process, BER-MPs underwent extensive oxidation and reduction in particle size, and the originally smooth surface developed numerous voids, accompanied by yellowing. Introduction of O atoms in the molecular chains increased their hydrophilicity, resulting in the polymer chains breaking away from the plastic particles and dissolving in water. Also, once BER was excited by light, environmentally persistent free radicals are produced on its surface. Moreover, the breaking of C-Br bonds occurred during the photodegradation process of BER-MPs, which suggested that tetrabromobisphenol A would be transformed during the photoaging process of BER even if it was covalently bound to BER.

Occurrence and emission characteristics of microplastics in agricultural surface runoff under different natural rainfall and short-term fertilizer application

Land-based microplastics (MPs) are considered the primary source of MPs in aquatic environments, with runoff being a major pathway for their transfer from soil to surface water. However, the transportation characteristics of MPs via agricultural surface runoff remain unclear. In this study, we investigated the occurrence and emission characteristics of MPs in agricultural surface runoff under various short-term fertilizer applications and natural rainfall events using laser direct infrared imaging analysis (LDIR). MPs from fertilizers and soils co-migrated with the agricultural runoff. The abundance and concentration of MPs in runoff were 145.90±22.48~2,043.38±89.51 items·L-1 and 39.17±21.94~523.04±47.85µg·L-1, respectively. Small and low-density MPs, such as polyethylene (PE), chlorinated polyethylene (CPE), and polyurethane (PU) in film/fragment form with 20~50µm exhibited a higher mobility. No statistical differences were observed in the distribution of runoff MPs with the application of different fertilizers. There was a significant positive relationship between runoff MP abundance and rainfall intensity. The annual emission load in this study area was 116.73g·hm-2, indicating that the transportation of MPs via agricultural surface runoff cannot be ignored. This study is conducive to understanding the migration behavior of MPs in soil-water environments in a better manner. Environmental significanceLand-based microplastics (MPs) serve as the primary source of contamination in aquatic ecosystems, with surface runoff being the predominantly transport pathway. However, the emission load and characteristics associated of MPs in agricultural runoff remain unclear. This study investigated the occurrence and emission of MPs in agricultural surface runoff under various short-term fertilization and natural rainfall. Co-migration of soil and fertilizer-derived MPs was observed. The maximum abundance and concentration of MPs in runoff were 2,043.38±89.51 items·L-1 and 523.04±47.85µg·L-1, respectively. Small and low-density MPs were easily mobilized. This study emphasizes the transportation of MPs via agricultural surface runoff cannot be ignored.

Metal leaching accompanied with natural photo-aging behavior of e-waste plastic derived microplastics in aquatic environment

As the main component of electronic products, plastics contain complex and diverse metal additives. Recycling process is not conducive to stable existence of metal additives in electronic plastics. Once the e-waste plastics enter the environment, they will continue to release harmful metals into environment after aging, causing serious hazards. This study delved into the analysis and comparison of metal content of e-waste plastics, elucidating aging process and metal leaching behavior over a 112-day natural light exposure period. The findings underscored that metal content in recycled plastics surpassed that in their new counterparts. Specifically, Ti content in new plastics remained below 100 mg/kg, while recycled plastics exhibited Ti content surpassing 100 mg/kg threshold. Throughout prolonged natural light exposure, metals such as Zn, Ba and Sb demonstrated a heightened likelihood of release from electronic plastics in comparison to other metals. The aging process during light exposure led to fragmentation of electronic plastics, accompanied by a reduction in particle size. Notably, the particle size reduction was more pronounced in poly acrylonitrile butadiene styrene (ABS) and recycled ABS, experiencing reductions of 40 µm and 85 µm, respectively. This phenomenon was attributed to the presence of polybutadiene structural units, which proved more susceptible to aging. Along with the breaking of plastics, the ABS plastics released metal species such as Pb, Cd, Ni, Al that had not been detected in other plastics solutions. The collective evidence from this study suggested that ABS and recycled ABS electronic plastics might pose a heightened potential environmental risk compared to other electronic plastics.

Aging and Small-sized Particles Release Characteristics of Tire Microplastics in Various Environmental Media

In recent years, research on microplastics has mostly focused on thermoplastic materials, and there is a lack of research on the pollution status and environmental behavior of tire microplastics, a type of rubber elastomers. In order to investigate the aging and small-sized particles release characteristics of tire microplastics in various environmental media, the aging process of two different tire microplastics, one for cars and the other for electric bicycles, was simulated in dry and aquatic environments under laboratory conditions. The results showed that the tire microplastics would be aged after 30 d of UV illumination, which was manifested by the roughness of the surface and the appearance of cracks and flaking. The Fourier infrared spectra showed that the carbonyl index of the surface also increased. In addition, tire microplastics released a large number of small sub-micron particles under the influence of UV illumination and hydrodynamic action, and the number of particles released from car tire microplastics in aquatic environments reached 694.8 million particles per milliliter of solution at 30 d of the UV light condition, among which 694.6 million particles with a particle size of less than 1 μm were released, which was approximately 100 times of that in the dark condition. The study showed that tire microplastics in aquatic environments were more susceptible to aging and released more small particles under light conditions and that car tire microplastics released more small particles than electric bicycle tire microplastics, posing ecological and environmental risks.

How plastic waste management affects the accumulation of microplastics in waters: a review for transport mechanisms and routes of microplastics in aquatic environments and a timeline for their fate and occurrence (past, present, and future)

An increasing global problem is the buildup of improperly handled plastic garbage in the environment. One of the biggest environmental issues facing aquatic ecosystems today is contamination from bulk plastics and plastic detritus. Specifically, microplastics (MPs) and nanoplastics, which are small-scale plastic waste, are now the main causes of pollution in freshwater and marine environments. On the other hand, contamination of aquatic systems is now acknowledged as one of the major environmental hazards facing our world. Currently, concerns have been raised regarding the breakdown of plastic products into micro and nanosized particles, because of the ineffective plastic waste management. To prioritize regions for mitigation policy implementation, it is critical to pinpoint the precise MPs’ transport mechanisms and the locations where trash is created. In order to show the historical and contemporary circumstances as well as forecasts and scenarios of global plastic waste management from now until 2060, we used continent-level data on trash management. This study, finally, presents a potential future scenario of estimates on the destiny, transport, and occurrence of plastic waste in aquatic habitats, highlighting the different factors that trigger the transport of MPs into water and the necessity of rational management of plastic waste.

Adsorption of Macrolide Antibiotics and a Metabolite onto Polyethylene Terephthalate and Polyethylene Microplastics in Aquatic Environments.

Microplastics (MPs) and antibiotics are emerging pollutants widely found in aquatic environments, potentially causing environmental harm. MPs may act as carriers for antibiotics, affecting their environmental distribution. This study investigates the adsorption of four macrolide antibiotics and a metabolite onto two types of MPs: polyethylene terephthalate (PET) and polyethylene (PE). Results revealed a linear isotherm adsorption model, with higher adsorption to PET than to PE (R2 > 0.936 for PE and R2 > 0.910 for PET). Hydrophobic interactions and hydrogen bonding could be the main adsorption mechanisms, with pore filling potentially involved. Reduced particle size enhances adsorption due to the increase of active adsorption sites. This increasement is more pronounced in PE than in PET, leading to an 11.6% increase in the average adsorption of all macrolides to PE, compared to only 5.1% to PET. Dissolved organic matter inhibits adsorption (azithromycin adsorption to PE was reduced from 12% to 5.1%), while salinity enhances it just until 1% salinity. pH slightly influences adsorption, with maximal adsorption at neutral pH. Results in real samples showed that complexity of the matrix decreased adsorption. Overall, these findings indicate that PE and PET MPs can be a vector of macrolides in aquatic environments.

Polystyrene microplastics enhance microcystin-LR-induced cardiovascular toxicity and oxidative stress in zebrafish embryos

The health risks associated with combined exposure to microplastics (MPs) and cyanobacteria toxins have gained increasing attention due to the large-scale prevalence of cyanobacterial blooms and accumulation of MPs in aquatic environments. Therefore, we explored the cardiovascular toxic effects of microcystin-LR (MC-LR, 1, 10, 100 μg/L) in the presence of 5 μm polystyrene microplastics (PS-MPs, 100 μg/L) and 80 nm polystyrene nanoplastics (PS-NPs, 100 μg/L) in zebrafish models. Embryos were exposed to certain PS-MPs and PS-NPs conditions in water between 3 h post-fertilization (hpf) and 168 hpf. Compared to MC-LR alone, a significant decrease in heart rate was observed as well as notable pericardial edema in the MC-LR + PS-MPs/NPs groups. At the same time, sinus venosus and bulbus arteriosus (SV-BA) distances were significantly increased. Furthermore, the addition of PS-MPs/NPs caused thrombosis in the caudal vein and more severe vascular damage in zebrafish larvae compared to MC-LR alone. Our findings revealed that combined exposure to PS-NPs and MC-LR could significantly decreased the expression of genes associated with cardiovascular development (myh6, nkx2.5, tnnt2a, and vegfaa), ATPase (atp1a3b, atp1b2b, atp2a1l, atp2b1a, and atp2b4), and the calcium channel (cacna1ab and ryr2a) compared to exposure to MC-LR alone. In addition, co-exposure with PS-MPs/NPs exacerbated the MC-LR-induced reactive oxygen species (ROS) production, as well as the ROS-stimulated apoptosis and heightened inflammation. We also discovered that astaxanthin (ASTA) treatment partially attenuated these cardiovascular toxic effects. Our findings confirm that exposure to MC-LR and PS-MPs/NPs affects cardiovascular development through calcium signaling interference and ROS-induced cardiovascular cell apoptosis. This study highlights the potential environmental risks of the co-existence of MC-LR and PS-MPs/NPs for fetal health, particularly cardiovascular development.

Modeling of microplastics degradation in aquatic environments using an experimental plan

The aim of this article is to apply advanced predictive modeling techniques to understand the degradation process of microplastics in aquatic environments. Utilizing a Fractional Factorial Central Composite Experimental Plan, this study seeks to develop precise predictive statistical models that enable forecasting the quantity of pollutants generated during the degradation of microplastics under various environmental conditions. This tool was applied to model changes in DOC (dissolved organic carbon) and DEHP (bis(2-ethylhexyl) phthalate) values during the degradation of microplastics in aquatic ecosystems. The methods were developed using data derived from laboratory tests conducted using the GC-MS technique. The obtained approximating functions, considering factors such as degradation time, water temperature, and particle size, significantly reduced the analysis time. A two-stage verification of the approximating functions was conducted, considering the accuracy of the function form, its adequacy, the statistical significance of input variables, and their correlation with DOC and DEHP. The employed a Fractional Factorial Central Composite Experimental Plan allowed for the simultaneous reduction in the number of experiments and prediction of the influence of variables on the output values. Precise predictive models support understanding of the microplastic degradation process, facilitating the development of effective strategies for managing this pollution.

Study of Advanced Techniques for Inquisition, Segregation and Removal of Microplastics from Water Streams: Current Insights and Future Directions

The present research covers different analytical methods utilized for the diagnosis and characterization of microplastics (MPs) in water and wastewater, such as particle size distribution analysis, and focuses on the sources and forms of MPs in receiving environments. First, we look at the most recent collection techniques, which include a variety of spectroscopic, chromatographic, and microscopic approaches used to identify and measure microplastics in water samples. We then investigate separation techniques designed to separate microplastics from diverse environmental matrices. This involves applying existing methods of separation based on density, such as centrifugation, flotation, and sedimentation, as well as more recent ones, like the use of microfluidic devices and materials for selective adsorption. Lastly, we look into removal methods aimed to reduce the buildup of microplastics in aquatic environments. These include enzymatic breakdown, coagulation/flocculation, and filtering, among other physical, chemical, and biological techniques.

Size-selective attachment of polyvinyl chloride microplastics on iron oxides in aqueous environments

The interaction of microplastics (MPs) with mineral particles is a crucial process determining the fate of MPs in aquatic environments, but potential size-selective interaction of MPs with minerals is unknown. In this work, strong and multi-layered attachment of a mix of heterogeneously size of polyvinyl chloride (PVC) MPs was observed on all the four types of iron oxides, following an order of Fe3O4-i > Fe3O4-s > γ-Fe2O3 > Fe3O4-n. Electrostatic attraction dominated their strong attachment, while hydrogen bonding and halogen bonding also contributed to MPs-mineral interaction. Importantly, both attachment rates and capacities were more favorable for large-sized PVC MPs (> 1.0 μm) than small-sized MPs (0.6–1.0 μm), due to more available attachment sites and stronger electrostatic attraction. Large-sized MPs preferred to detach from iron oxides before small-sized MPs, confirming by configuration analysis. The attachment accelerated the sedimentation of PVC MPs, while a fraction (i.e., 26.7 %, PVC/iron oxide ratio at 0.2:1) of heteroaggregates floated at the air–water interface associated with bubbles. Natural organic matter decreased MPs-mineral interaction due to competitive adsorption, electrostatic repulsion, and steric hindrance, while the attachment was enhanced with increasing ionic strengths (0–200 mM). These findings contribute to a better understanding of the transport and fate of MPs in aquatic systems.

Understanding microplastic aging driven by photosensitization of algal extracellular polymeric substances

The aging of microplastics (MPs) is extremely influenced by photochemically-produced reactive intermediates (PPRIs), which are mediated by natural photosensitive substances. Algal extracellular polymeric substances (EPS) can produce PPRIs when exposed to sunlight. Nonetheless, the specific role of EPS in the aging process of MPs remains unclear. This work systematically explored the aging process of polystyrene (PS) MPs in the EPS secreted by Chlorella vulgaris under simulated sunlight irradiation. The results revealed that the existence of EPS accelerated the degradation of PS MPs into particles with sizes less than 1 µm, while also facilitating the formation of hydroxy groups on the surface. The release rate of dissolved organic matter (DOM) from PS MPs was elevated from 0.120 mg·L-1·day-1 to 0.577 mg·L-1·day-1. The primary factor contributing to the elevated levels of DOM was humic acid-like compounds generated through the breakdown of PS. EPS accelerated the aging process of PS MPs by primarily mediating the formation of triplet excited states (3EPS*), singlet oxygen (1O2), and superoxide radicals (O2∙-), resulting in indirect degradation. 3EPS* was found to have the most substantial impact. This study makes a significant contribution to advance understanding of the environmental fate of MPs in aquatic environments impacted by algal blooms.

Assessing biofilm formation and resistance of vibrio parahaemolyticus on UV-aged microplastics in aquatic environments

UV degradation of marine microplastics (MPs) could increase their vector potential for pathogenic bacteria and threaten human health. However, little is known about how the degree of UV aging affects interactions between MPs and pathogens and how various types of MPs differ in their impact on seafood safety. This study investigated five types of UV-aged MPs and their impact on Vibrio parahaemolyticus, a seafood pathogen. MPs exposed to UV for 60 days showed similar physicochemical changes such as surface cracking and hydrophobicity reduction. Regardless of the type, longer UV exposure of MPs resulted in more biofilm formation on the surface under the same conditions. V. parahaemolyticus types that formed biofilms on the MP surface showed 1.4- to 5.0-fold upregulation of virulence-related genes compared to those that did not form biofilms, independently of UV exposure. However, longer UV exposure increased resistance of V. parahaemolyticus on MPs to chlorine, heat, and human gastrointestinal environment. This study implies that the more UV degradation occurs on MPs, the more microbial biofilm formation is induced, which can significantly increase virulence and environmental resistance of bacteria regardless of the type of MP.

Insight into the adsorption behaviors and bioaccessibility of three altered microplastics through three types of advanced oxidation processes

Advanced oxidation processes (AOPs) can significantly alter the structural properties, environmental behaviors and human exposure level of microplastics in aquatic environments. Three typical microplastics (Polyethylene (PE), polypropylene (PP), and polystyrene (PS)) and three AOPs (Heat-K2S2O8 (PDS), UV-H2O2, UV-peracetic acid (PAA)) were adopted to simulate the process when microplastics exposed to the sewage disposal system. 2-Nitrofluorene (2-NFlu) adsorption experiments found the equilibrium time decreased to 24 hours and the capacity increased up to 610 μg g−1, which means the adsorption efficiency has been greatly improved. The fitting results indicate the adsorption mechanism shifted from the partition dominant on pristine microplastic to the physical adsorption (pore filling) dominant. The alteration of specific surface area (21 to 152 m2 g−1), pore volume (0.003 to 0.148 cm3 g−1) and the particle size (123 to 16 μm) of microplastics after AOPs are implying the improvement for pore filling. Besides, the investigation of bioaccessibility is more complex, AOPs alter microplastic with more oxygen-containing functional groups and lower hydrophobicity detected by XPS and water contact angle, those modifications have increased the sorption concentration, especially in the human intestinal tract. Therefore, this indicates the actual exposure of organic compounds loaded in microplastic may be higher than in the pristine microplastic. This study can help to assess the human health risk of microplastic pollution in actual environments.

Revealing the environmental hazard posed by biodegradable microplastics in aquatic ecosystems: An investigation of polylactic acid's effects on Microcystis aeruginosa

The influence of petroleum-based microplastics (MPs) on phytoplankton has been extensively studied, while research on the impact of biodegradable MPs, derived from alternative plastics to contest the environmental crisis, remains limited. This study performed a 63 days co-incubation experiment to assess the effect of polylactic acid MPs (PLA-MPs) on the growth, physiology, and carbon utilization of M. aeruginosa and the change in PLA-MPs surface properties. The results showed that despite PLA-MPs induced oxidative stress and caused membrane damage in M. aeruginosa, the presence of PLA-MPs (10, 50, and 200 mg/L) triggered significant increases (p < 0.05) in the density of M. aeruginosa after 63 days. Specifically, the algal densities upon 50 and 200 mg/L PLA-MPs exposure were increased by 20.91% and 36.31% relative to the control, respectively. Meanhwhile, the reduced C/O ratio on PLA-MPs surface and change in PLA-MPs morphological characterization, which is responsible for substantially increase in the aquatic dissolved inorganic carbon concentration during the co-incubation, implying the degradation of PLA-MPs; thus, provided sufficient carbon resources that M. aeruginosa could assimilate. This was in line with the declined intracellular carbonic anhydrase content in M. aeruginosa. This study is the first attempt to uncover the interaction between PLA-MPs and M. aeruginosa, and the finding that their interaction promotes the degrading of PLA-MPs meanwhile favoring M. aeruginosa growth will help elucidate the potential risk of biodegradable MPs in aquatic environment.

A review on microplastics in major European rivers

AbstractThe topic of riverine microplastics is of great interest to the general public, yet the univocal scientific knowledge on this topic is limited. This review investigated the occurrence of microplastics in 6 major European rivers and their tributaries based on the results from 29 studies. We examined the reviewed studies in regard to data quality and reproducibility and assessed the abundance of microplastics in different sections of the water column. Furthermore, we investigated the chemical composition and potential origin of the reported riverine microplastics. We found that polystyrene, polypropylene, and polyethylene were the most abundant polymer types. The majority of primary microplastics arose from the industry sector as well as from personal care and cleaning products, whereas secondary microplastics constituted fibers from synthetic textiles and fragments of diverse origins. We highlighted the diversity of experimental and analytical approaches that could lead to high uncertainties in the measurements of microplastics abundance. Furthermore, the presence of microplastics in rivers was found to vary spatially likely due to point and nonpoint pollution sources of anthropogenic activities. Heterogenous environmental processes impacted the fate of microplastics characterized by various forms, sizes, and densities, in different ways. This impeded the identification of representative quantitative measurements of microplastics across different time frames. We advocate for the development of standardized protocols by the research community to ensure higher reproducibility of sampling, processing, and analysis of microplastics in aquatic environments. We recommend long‐term and site‐specific monitoring on microplastics with high data comparability to better inform policy making.This article is categorized under: Science of Water &gt; Water Quality Water and Life &gt; Conservation, Management, and Awareness

(Digital Presentation) Electrochemical Study of Mxene-Metal Oxide Composites for the Degradation of PVC-Based Microplastics

Microplastics (MPs) are fragments of any type of plastic less than 5mm in length, and it is harmful to our ocean and aquatic life. In recent years, the prevalence of MPs in aquatic environments has grown to be a serious environmental problem that has recently gained lots of attention [1, 2]. However, there is still a lack of studies on electrocatalytic treatment for an effective breakdown of MPs [3]. Here, Mxene-Metaloxide composites modified graphite electrode-based electro-fenton (EF) technology has been proposed to break down polyvinyl chloride (PVC) MPs. Advanced oxidation processes are widely studied and applied for the decomposition of MPs. Hydroxyl radicals (•OH) were generated by the electro-oxidation (EO) and electro-peroxidation (EO- ) process which has exhibited great capability for catalytic degradation of MPs and converted into H2O and CO2.In this work, electro-oxidation was carried out in a three-electrode system with an oxygen-saturated environment where Mxene-Metaloxide composites modified graphite electrode, graphite electrode, and Ag/AgCl electrode were used as a working electrode, counter electrode, and reference electrode respectively. Different operating parameters such as electrolyte type, electrolyte concentration, temperature, and reaction time were maintained for EO. Cyclic voltammetry was employed to analyze the catalytic performance of the MXene-TiO2/C modified graphite electrode in the context of the Oxygen Reduction Reaction. The obtained results revealed that the EO process can degrade 54.5% of MPs after potentiostatic electrolysis at -0.7V Ag/AgCl at 80 °C for 6 hours. Fig 1 presents the removal efficiency of PVC MPs in 0.05M Na2SO4 solution. The results from scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), UV-Vis spectroscopy, and Energy dispersive X-ray spectroscopy (EDX) revealed that the MPs degraded directly into CO2 and H2O. The results of this research showed that such a heterogeneous EF-like technology using Mxene-metal oxide composites modified graphite electrode was hoped to give an eco-friendly technique for treating MPs in wastewater.

Exploring the relation between aggregation and adsorption of microplastics in aquatic environment containing metal cations

Metal cations can be adsorbed on the surface of PSMPs which change the surface properties of PSMPs and lead to the aggregation of PSMPs in aqueous solution. However, previous studies have only examined the processes of aggregation and adsorption independently, without investigating the correlation of adsorption and aggregation. In this study, the adsorption and aggregation experiment were carried out simultaneously and monitored simultaneously. The results of this study reveal that, prior to charge reversal of polystyrene microplastic (PSMPs), both adsorption and aggregation increased gradually with increasing metal cations concentration, and were mutually reinforcing. However, following charge reversal, adsorption increased while aggregation decreased, indicating that adsorption inhibited aggregation. The Zeta potentials of PSMPs increase consistently with increasing metal cations concentrations suggested that electrostatic force was one of the primary mechanisms for the adsorption of metal cations by PSMPs. The FTIR analysis reveal that the peak corresponding to CC stretching shifted from 1630 cm−1 to 1628 cm−1, 1621 cm−1, and 1615 cm−1 when Ag+, Cu2+ or Cr3+ metal cations were existed, and the results indicated that there might be interactions such as cations-π between PSMPs and metal cations. This information is crucial in determining the environmental fate and impact of PSMPs that have adsorbed metal cations pollutants.

Comprehensive analysis reveals the differentiated influential mechanism of degradable poly (ε-caprolactone) and polybutylene succinate microplastics on nitrogen transformation in aerobic granular sludge systems

The escalating releasing of degradable microplastics (DMPs) into wastewater may pose a potential threat to biological nitrogen removal. However, whether and how different DMPs affect nitrogen transformations in aerobic granular sludge (AGS) systems remains unclear. This work therefore aimed to fill such knowledge gaps by employing poly (ε-caprolactone) (PCL) and polybutylene succinate (PBS) as the model microplastics. Results revealed that exposure to 0.5 and 5 mg/L DMPs did not remarkably affect the nitrogen removal. However, increasing DMPs concentration to 50 mg/L suppressed the nitrogen transformation, causing a significant degree of inhibition in total nitrogen removal efficiency, particularly in the PCL-exposure group (decreased by 2.0%–25.7%). The pronounced inhibitory effects were attributed to the more readily biodegradability of PCL compared to PBS, resulting in an enhanced release of microplastics that induced excessive production of reactive oxygen species and destruction of cytomembrane integrity. Consequently, the relative abundance of denitrifiers was decreased, leading to suppressed expression of the genes (e.g. narG) involved in nitrogen transformation. This was accompanied by a decline in enzyme activity (e.g. nitrate reductase) and electron transport system activity. The correlations among genes, microbes and environmental factors were reshaped by different DMPs, underlying the intrinsic mechanism for the deteriorated nitrogen removal. Overall, this study implies that compared to PBS microplastics, the accumulation of PCL microplastics in aquatic environments poses a more significant threat to biological treatment efficacy and global nitrogen cycling, thereby warranting increased attention.

Advances in analysis of microplastics in drinking water treatment plants. Fluorescence techniques using iDye Pink

Recently, the increasing amount of plastic waste has raised concerns about microplastics in aquatic environments. In this study, microplastics between 0.1 and 5 mm in samples from different points of three Drinking Water Treatment Plants (DWTP) were separated, quantified, and identified. Staining methods were used in combination with microscopic and spectroscopic techniques. On the one hand, the Rose Bengal dye was used to discriminate between natural and synthetic particles. On the other hand, Nile Red and iDye Pink reagents have been evaluated for staining microplastics, providing them with fluorescence. The nature of the particles is determined by comparison with a series of patterns by means of an epifluorescence microscope. In addition, "Micro Fourier Transform Spectrophotometer " and "Raman Spectroscopy" were used to identify the nature of the particles more accurately. Concerning the results, polyester was the most common material by fluorescence identification, and it was confirmed with Raman spectroscopy. Since most of the particles observed were microfibres, Raman proved to be a better identification technique than μ-FTIR, which could only identify large fragments. In addition, the global elimination of microplastics (MPs) resulted notable in the three DWTPs, being 81.47% for A, 88.98% for B, and 82.27% for C, thus guaranteeing a higher quality of drinking water.

Polystyrene microplastics enhance oxidative dissolution but suppress the aquatic acute toxicity of a commercial cadmium yellow pigment under simulated irradiation

Commercial cadmium yellow (CdS) pigment widely coexist with microplastics (MPs) in surface water, thus it is important to understand how MPs affect CdS pigment stability and toxicity under irradiation. Herein, the dissolution of CdS pigment (krelease = 0.118 h–1) under irradiation was visibly increased to 0.144 h–1 by polystyrene (PS) MPs, due to reactive species generation such as 1O2, •OH and 3PS* , while O2•− was unimportant to this process. The O2, humic acid, photoaging status of PS MPs could promote PS MPs-related CdS pigment dissolution rate by modifying reactive species generation. However, the CO32−, PO43− and alkaline condition significantly decreased the dissolution rate to 0.091, 0.053 and 0.094 h–1, respectively, through modifying free Cd2+ stability. Comparably, PS MPs-related CdS pigment dissolution was relatively slow in natural water samples (krelease = 0.075 h–1). PS MPs at environmental concentration can also promote CdS pigment dissolution and Cd2+ release, but suppress acute toxicity of CdS pigment to zebrafish larvae as increasing 10 h survival from 65% to 85% by adsorbing the Cd2+ and decreasing Cd2+ bioavailability. This study emphasized the environmental risks and human safety of CdS pigment should be carefully evaluated in the presence of PS MPs in aquatic environments.