Recent advances towards micro(nano)plastics research in wetland ecosystems: A systematic review on sources, removal, and ecological impacts

Impacts of plastic pollution on soil-plant properties and greenhouse gas emissions in wetlands: A meta-analysis

Plastic pollution in wetlands has recently emerged as an urgent environmental problem. However, the impacts of plastic contamination on soil-plant properties and greenhouse gas (GHG) emissions in wetlands remain unclear. Thus, this study conducted a meta-analysis based on 44 study sites to explore the influence of plastic pollution on soil physicochemical variables, soil microorganisms, enzyme activity, functional genes, plant characteristics, and GHG emissions (CO2, CH4, and N2O) in different wetland types. Based on the collected dataset, the plastic pollution significantly increased soil organic matter and organic carbon by on average 28.9 % and 34.2 %, respectively, while decreased inorganic nutrient elements, bacteria alpha diversity and enzyme activities by an average of 5.9 -14.2 %. The response of bacterial abundance to plastic pollution varied depending on phylum classes. Plant biomass and photosynthetic efficiency were decreased by an average of 12.8 % and 18.4 % due to plastic pollution. The concentration and exposure time of plastics play a key role in influencing the soil and plant properties in wetlands. Furthermore, plastic exposure notably increased the abundance of the functional genes related to C degradation and the ammonia oxidizing microorganisms, and the consequent CO2 and N2O emissions (with effect sizes of 2.10 and 1.94, respectively). We also found that plastic concentrations and exposure duration affected the wetland soil-plant system. Our results might be helpful to design further investigations on plastic effects and develop appropriate measures for mitigating plastic pollution in wetlands.

Unveiling the microplastic perturbation on surface flow constructed wetlands with macrophytes of different life forms: Responses of nitrogen removal and sensory quality

Microplastics (MPs) discharging into constructed wetlands pose risks to these ecosystems. Nevertheless, the perturbation of MPs to different types of macrophytes, which play important roles in purifying pollutants of wetlands, has not been fully elucidated. In this study, polystyrene MPs (PS-MPs) perturbation on nitrogen removal and sensory quality of surface flow constructed wetlands planted with emergent and submerged macrophytes were investigated. PS-MPs enhanced N removal efficiencies temporarily, whereas the N removal rate constants were declined as exposure time was prolonged. The NH4+-N removal rate constants declined by 25.78 % and 34.03 % in E and S groups respectively. The NO3--N removal rate constants declined by 22.13 % in the S groups. Denitrifiers including Thiobacillus, Rhodobacter, and Sulfuritalea were stressed. The sensory quality deteriorated after PS-MPs exposure, which was significantly related to changes in Chlorophyll a, particle size distribution, and colored dissolved organic matter. Turbidity in E groups and chroma in S groups were greatly affected by PS-MPs. Overall, under MPs exposure, macrophytes in E groups were more suitable for nitrogen removal, and macrophytes in S groups better purified the turbidity. The study could provide the basis for better allocation of macrophytes in CWs to reduce the purifying risk by PS-MPs disturbance.

Polystyrene nanoplastics induce cell type-dependent secondary wall reinforcement in rice (Oryza sativa) roots and reduce root hydraulic conductivity

Nanoplastics (NPs) have been demonstrated the ability to penetrate plant roots and cause stress. However, the extent of NPs penetration into various root tissues and the corresponding plant defense mechanisms remain unclear. This study examined the penetration and accumulation patterns of polystyrene nanoplastics (PS-NPs) in different cell types within rice roots, and explored how the roots quickly modify their cell wall structure in response. The findings showed that fully developed sclerenchyma cells in rice roots effectively prevented the invasion of PS-NPs. Meanwhile, PS-NPs triggered the accumulation of lignin and suberin in specific cells such as the exodermis, sclerenchyma, and xylem vessels. PS-NPs at a concentration of 50 mg L-1 increased cell wall thickness by 18.6 %, 21.1 %, and 22.4 % in epidermis, exodermis, and sclerenchyma cells, respectively, and decreased root hydraulic conductivity by 14.8 %. qPCR analysis revealed that PS-NPs influenced the cell wall synthesis pathway, promoting the deposition of lignin and suberin monomers on the secondary wall through the up-regulation of genes such as OsLAC and OsABCG. These results demonstrate that PS-NPs can induce cell type-specific strengthening of secondary walls and barrier formation in rice roots, suggesting the potential role of plant secondary wall development in mitigating NPs contamination risks in crops.

Nanoplastics enhance the denitrification process and microbial interaction network in wetland soils

With the widespread presence of plastic waste in ecosystems, it is imperative to understand the response of natural processes to micro- and nanoplastic pollution pressures. However, the effects of nanoplastics on biogeochemical cycles are still overlooked and controversial. This study investigated the effects of three particle sizes (100 μm, 7 μm, and 80 nm) of polystyrene (PS) micro/nanoplastics (0.08 % of mass concentration) on denitrification processes and nirS/nirK denitrifying bacterial communities in wetland soils. The results indicated that PS nanoplastics were found to significantly enhance denitrification rates from 21.30 to 54.73 μmol N2·h-1·kg-1, increasing by 1.57 times compared to the control. Exposure to nanoplastics caused shifts in the composition and structure of the nirS-type denitrifier community. LEfSe analysis, random forest, and Mantel tests revealed that nirS denitrifying bacteria, especially Sideroxydans, played a pivotal role in driving denitrification rates (Mantel's R = 0.24, p = 0.002), likely due to the faster release of organic substrates from nanoplastics. Microbial co-occurrence networks demonstrated that nanoplastic amendments fostered a denser denitrifier network and led to shifts in keystone species. Sideroxydans appeared more likely to cooperate with other bacteria, such as Burkholderiales, to complete denitrification processes. This study suggests that nanoplastics are a potentially stronger driver of denitrification than microplastics, providing insight into the impact of plastic pollutants on biogeochemical cycling in natural wetland ecosystems. Given the widespread distribution of wetlands, the potential increase in gaseous nitrogen emissions due to nanoplastics pollution warrants attention.

Genotoxicity and metabolic changes induced via ingestion of virgin and UV-aged polyethylene microplastics by the freshwater fish Perca fluviatilis

The present study aims to compare and assess the toxicity induced by aged (irradiated with ultraviolet radiation for 120 days) polyethylene microplastics (PE-MPs) in comparison to virgin (non-irradiated) ones, after feeding the freshwater fish Perca fluviatilis. To this end, MPs mediated genotoxicity was assessed by the investigation of micronucleus nuclear abnormalities frequency in fish blood, and the degree of DNA damage in the liver and muscle tissues, while metabolic alterations were also recorded in both tissues. Results showed that both virgin and aged PE-MPs induced signaling pathways leading to DNA damage and nuclear abnormalities, as well as metabolites changes in all tissues studied. Metabolic changes revealed that the metabolism of nucleic acids, energy, amino acids, and neurotransmitters was more disrupted in the liver and by aged PE-MPs compared to muscles. Fish fed with aged PE-MPs exhibited greater DNA damage, while blood cells of fish fed with virgin PE-MPs seemed to be more vulnerable to nuclear abnormalities in relation to those fed with aged PE-MPs. Moreover, aged PE-MPs induced more acute overall effects on the metabolic profiles of fish tissues, and initiated stronger stress responses, inflammation, and cellular damages in fish tissues in relation to virgin ones. Characterization of both virgin and aged MPs revealed that the latter exhibited lower crystallinity and melting point, more irregular shapes and higher moiety of oxygen and carbonyl groups, which could be attributed for their observed higher toxicity. The research outcomes provide significant insights for advancing toxicological investigations in this field.

Ciprofloxacin affects nutrient removal in manganese ore-based constructed wetlands: Adaptive responses of macrophytes and microbes

Ciprofloxacin (CIP) has received considerable attention in recent decades due to its high ecological risk. However, little is known about the potential response of macrophytes and microbes to varying levels of CIP exposure in constructed wetlands. Therefore, lab-scale manganese ore-based tidal flow constructed wetlands (MO-TFCWs) were operated to evaluate the responses of macrophytes and microbes to CIP over the long term. The results indicated that total nitrogen removal improved from 79.93% to 87.06% as CIP rose from 0 to 4 mg L-1. The chlorophyll content and antioxidant enzyme activities in macrophytes were enhanced under CIP exposure, but plant growth was not inhibited. Importantly, CIP exposure caused a marked evolution of the substrate microbial community, with increased microbial diversity, expanded niche breadth and enhanced cooperation among the top 50 genera, compared to the control (no CIP). Co-occurrence network also indicated that microorganisms may be more inclined to co-operate than compete. The abundance of the keystone bacterium (involved in nitrogen transformation) norank_f__A0839 increased from 0.746% to 3.405%. The null model revealed drift processes (83.33%) dominated the community assembly with no CIP and 4 mg L-1 CIP. Functional predictions indicated that microbial carbon metabolism, electron transfer and ATP metabolism activities were enhanced under prolonged CIP exposure, which may contribute to nitrogen removal. This study provides valuable insights that will help achieve stable nitrogen removal from wastewater containing antibiotic in MO-TFCWs.

Effect of tire wear particle accumulation on nitrogen removal and greenhouse gases abatement in bioretention systems: Soil characteristics, microbial community, and functional genes

Tire wear particles (TWPs), as predominant microplastics (MPs) in road runoff, can be captured and retained by bioretention systems (BRS). This study aimed to investigate the effect of TWPs accumulation on nitrogen processes, focusing on soil characteristics, microbial community, and functional genes. Two groups of lab-scale bioretention columns containing TWPs (0 and 100 mg g-1) were established. The removal efficiencies of NH4+-N and TN in BRS significantly decreased by 7.60%-24.79% and 1.98%-11.09%, respectively, during the 101 days of TWPs exposure. Interestingly, the emission fluxes of N2O and CO2 were significantly decreased, while the emission flux of CH4 was substantially increased. Furthermore, prolonged TWPs exposure significantly influenced the contents of soil organic matter (increased by 27.07%) and NH4+-N (decreased by 42.15%) in the planting layer. TWPs exposure also significantly increased dehydrogenase activity and substrate-induced respiration rate, thereby promoting microbial metabolism. Microbial sequencing results revealed that TWPs decreased the relative abundance of nitrifying bacteria (Nitrospira and Nitrosomonas) and denitrifying bacteria (Dechloromonas and Thauera), reducing the nitrification rate by 42.24%. PICRUSt2 analysis further indicated that TWPs changed the relative abundance of functional genes related to nitrogen and enzyme-coding genes.

Toxicological review of micro- and nano-plastics in aquatic environments: Risks to ecosystems, food web dynamics and human health

The increase of micro- and nano-plastics (MNPs) in aquatic environments has become a significant concern due to their potential toxicological effects on ecosystems, food web dynamics, and human health. These plastic particles emerge from a range of sources, such as the breakdown of larger plastic waste, consumer products, and industrial outputs. This review provides a detailed report of the transmission and dangers of MNPs in aquatic ecosystems, environmental behavior, and interactions within aquatic food webs, emphasizing their toxic impact on marine life. It explores the relationship between particle size and toxicity, their distribution in different tissues, and the process of trophic transfer through the food web. MNPs, once consumed, can be found in various organs, including the digestive system, gills, and liver. Their consumption by lower trophic level organisms facilitates their progression up the food chain, potentially leading to bioaccumulation and biomagnification, thereby posing substantial risks to the health, reproduction, and behavior of aquatic species. This work also explores how MNPs, through their persistence and bioaccumulation, pose risks to aquatic biodiversity and disrupt trophic relationships. The review also addresses the implications of MNPs for human health, particularly through the consumption of contaminated seafood, highlighting the direct and indirect pathways through which humans are exposed to these pollutants. Furthermore, the review highlights the recommendations for future research directions, emphasizing the integration of ecological, toxicological, and human health studies to inform risk assessments and develop mitigation strategies to address the global challenge of plastic pollution in aquatic environments.

Nitrogen supply neutralizes the nanoplastic-plant interaction in a coastal wetland

The presence of nanoplastics posed a potential threat to coastal saline-alkaline wetlands where nitrogen (N) fertilizer is being implemented as an important ecological restoration measure. Notwithstanding, the effects of N inputs on plant community in polypropylene-nanoplastics (PP-NPs) coexistence environments are largely unknown. To address this, we investigated the effects of PP-NPs addition alone or combined N supply on community aboveground biomass, morphological traits, diversity, composition, niche differentiation, interspecific interactions, and assembly. Our results showed that the PP-NPs addition alone reduced community aboveground biomass and morphological traits. However, the addition of high concentration (0.5%) PP-NPs alone favored community α-diversity and reduced community stability, which could be weakened through combined N supply. Overall, the effect of PP-NPs addition alone on plant community composition was greater than that of combined N supply. We also demonstrated PP-NPs addition alone and combined N supply reduced the niche breadth of the plant community and affected the niche overlap of dominant species. In the assembly of plant communities, stochastic processes played a dominant role. We conclude that N fertilization can amend the terrestrial nanoplastics pollution, thus mitigating the effects of PP-NPs on the plant community.

Impact of Polyethylene Terephthalate Microplastics on Drosophila melanogaster Biological Profiles and Heat Shock Protein Levels

Microplastics and nanoplastics are abundant in the environment. Further research is necessary to examine the consequences of microplastic contamination on living species, given its widespread presence. In our research, we determined the toxic effects of PET microplastics on Drosophila melanogaster at the cellular and genetic levels. Our study revealed severe cytotoxicity in the midgut of larvae and the induction of oxidative stress after 24 and 48 h of treatment, as indicated by the total protein, Cu-Zn SOD, CAT, and MDA contents. For the first time, cell damage in the reproductive parts of the ovaries of female flies, as well as in the accessory glands and testes of male flies, has been observed. Furthermore, a decline in reproductive health was noted, resulting in decreased fertility among the flies. By analyzing stress-related genes such as hsp83, hsp70, hsp60, and hsp26, we detected elevated expression of hsp83 and hsp70. Our study identified hsp83 as a specific biomarker for detecting early redox changes in cells caused by PET microplastics in all the treated groups, helping to elucidate the primary defense mechanism against PET microplastic toxicity. This study offers foundational insights into the emerging environmental threats posed by microplastics, revealing discernible alterations at the genetic level.

Microplastics removal mechanisms in constructed wetlands and their impacts on nutrient (nitrogen, phosphorus and carbon) removal: A critical review

Microplastics (MPs) are now prevalent in aquatic ecosystems, prompting the use of constructed wetlands (CWs) for remediation. However, the interaction between MPs and CWs, including removal efficiency, mechanisms, and impacts, remains a subject requiring significant investigation. This review investigates the removal of MPs in CWs and assesses their impact on the removal of carbon, nitrogen, and phosphorus. The analysis identifies crucial factors influencing the removal of MPs, with substrate particle size and CWs structure playing key roles. The review highlights substrate retention as the primary mechanism for MP removal. MPs hinder plant nitrogen uptake, microbial growth, community composition, and nitrogen-related enzymes, reducing nitrogen removal in CWs. For phosphorus and carbon removal, adverse effects of MPs on phosphorus elimination are observed, while their impact on carbon removal is minimal. Further research is needed to understand their influence fully. In summary, CWs are a promising option for treating MPs-contaminated wastewater, but the intricate relationship between MPs and CWs necessitates ongoing research to comprehend their dynamics and potential consequences.

Micro- and nano-plastics in the atmosphere: A review of occurrence, properties and human health risks

The ubiquitous occurrence of micro/nano plastics (MNPs) poses potential threats to ecosystem and human health that have attracted broad concerns in recent decades. Detection of MNPs in several remote regions has implicated atmospheric transport as an important pathway for global dissemination of MNPs and hence as a global health risk. In this review, the latest research progress on (1) sampling and detection; (2) origin and characteristics; and (3) transport and fate of atmospheric MNPs was summarized. Further, the current status of exposure risks and toxicological effects from inhaled atmospheric MNPs on human health is examined. Due to limitations in sampling and identification methodologies, the study of atmospheric nanoplastics is very limited today. The large spatial variation of atmospheric MNP concentrations reported worldwide makes it difficult to compare the overall indoor and outdoor exposure risks. Several in vitro, in vivo, and epidemiological studies demonstrate adverse effects of immune response, apoptosis and oxidative stress caused by MNP inhalation that may induce cardiovascular diseases and reproductive and developmental abnormalities. Given the emerging importance of atmospheric MNPs, the establishment of standardized sampling-pretreatment-detection protocols and comprehensive toxicological studies are critical to advance environmental and health risk assessments of atmospheric MNPs.

Development of Enzyme-Based Approaches for Recycling PET on an Industrial Scale

Pollution by plastics such as polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), polyurethane (PUR), polyamide (PA), polystyrene (PS), and poly(ethylene terephthalate) (PET) is now gaining worldwide attention as a critical environmental issue, closely linked to climate change. Among them, PET is particularly prone to hydrolysis, breaking down into its constituents, ethylene glycol (EG) and terephthalate (TPA). Biorecycling or bioupcycling stands out as one of the most promising methods for addressing PET pollution. For dealing with pollution by the macrosize PET, a French company Carbios has developed a pilot-scale plant for biorecycling waste PET beverage bottles into new bottles using derivatives of thermophilic leaf compost cutinase (LCC). However, this system still provides significant challenges in its practical implementation. For the micro- or nanosize PET pollution that poses significant human health risks, including cancer, no industrial-scale approach has been established so far, despite the need to develop such technologies. In this Perspective, we explore the enhancement of the low activity and thermostability of the enzyme PETase to match that of LCC, along with the potential application of microbes and enzymes for the treatment of waste PET as microplastics. Additionally, we discuss the shortcomings of the current biorecycling protocols from a life cycle assessment perspective, covering aspects such as the diversity of PET-hydrolyzing enzymes in nature, the catalytic mechanism for crystallized PET, and more. We also provide an overview of the Ideonella sakaiensis system, highlighting its ability to operate and grow at moderate temperatures, in contrast to high-temperature processes.

Bioaccumulation of polystyrene nanoplastics and BDE-209 induced oxidative stress, photosynthesis and growth impairments in floating fern Salvinia natans

Aquatic ecosystems are facing increasing exposure to pollutants, posing potential threats to the stability and wellness of aquatic species. This study focused on evaluating the impacts of single and combined exposure to 80 nm polystyrene nanoplastics (PS-NPs, 0.1, 1, 10, 20 mg/L) and decabromodiphenyl ether (BDE-209, 300 ng/L) for 14 days on the bioaccumulation, growth, photosynthesis and oxidative stress in the free-floating fern Salvinia natans. PS-NPs primarily accumulated in the epidermis and trichomes of S. natans. Meanwhile, the levels of superoxide dismutase (SOD) and malondialdehyde (MDA) were significantly increased, while those for peroxidase (POD), catalase (CAT), total antioxidant capacity (T-AOC), and relative growth rate (RGR) decreased. Furthermore, the chlorophyll contents in submerged leaves were decreased, while those in floating leaves were increased at PS-NPs concentrations of 0.1 and 1 mg/L. However, the chlorophyll contents in both submerged and floating leaves displayed a decreasing trend with increasing concentrations of PS-NPs. Under the co-exposure of PS-NPs and BDE-209, the contents of MDA were significantly elevated, whereas CAT, POD, SOD, T-AOC and RGR were significantly decreased (p < 0.05). Our results revealed that, compared to single exposure, more pronounced ecotoxic effects are observed in S. natans under co-exposure to PS-NPs and BDE-209. These findings offer valuable perspectives into the possible environmental risks of BDE-209 and PS-NPs in freshwater ecosystems, contributing to the development of effective management strategies for protecting aquatic organisms and ecosystems. This research highlights the urgent need to understand the toxic effects of emerging contaminants on different aquatic organisms, emphasizing the importance of protecting and preserving aquatic ecosystems.

Polystyrene microplastics accumulation in lab-scale vertical flow constructed wetlands: impacts and fate

Microplastics (MPs) are ubiquitous pollutants that significantly threaten organisms and ecosystems. Constructed wetlands (CWs), a nature-based treatment technology, can effectively remove MPs from wastewater. However, the responses of CWs when exposed to MPs remain unclear. In this study, lab-scale vertical flow constructed wetlands (VFCWs) were installed for receiving polystyrene (PS) MPs at concentrations of 100 μg/L and 1000 μg/L. The results showed that exposure to PS-MPs has no effects on COD and TP removal in VFCWs, but TN removal decreased by 3.69-5.37 %. Further investigation revealed that PS-MPs significantly impacted microbial communities and metabolic functions. The abundances of predominant nitrifiers (Nitrospira and Nitrosomonas) and denitrifiers (Nakamurella, Bradyrhizobium, and Bacillus) in VFCWs were significantly reduced, aligning with the responses of key enzymes. The presence of PS-MPs also decreased nitrogen removal by plant uptake, leading to decreased plant biomass and chlorophyll by 39.32-48.75 % and 5.92-32.19 %, respectively. Notably, > 90 % removal rates were observed for PS-MPs within VFCWs. In addition to PS-MPs interception by VFCWs substrate, the increase of released benzenes indicated that the PS-MPs biodegradation occurred. Such insights are vital for developing sustainable solutions to mitigate MPs' adverse effects on ecosystems.

Effects of microplastics on the properties of different types of sewage sludge and strategies to overcome the inhibition: A review

Microplastics have been identified as an emerging pollutant. When microplastics enter wastewater treatment plants, the plant traps most of the microplastics in the sludge during sewage treatment. Therefore, the effects of microplastics on sludge removal performance, and on the physical and chemical properties and microbial communities in sludge, have attracted extensive attention. This review mainly describes the presence of microplastics in wastewater treatment plants, and the effects of microplastics on the decontamination efficiency and physicochemical properties of activated sludge, aerobic granular sludge, anaerobic granular sludge and anaerobic ammonium oxidation sludge. Further, the review summarizes the effects of microplastics on microbial activity and microbial community dynamics in various sludges in terms of type, concentration, and contact time. The mechanisms used to strengthen the reduction of microplastics, such as biochar and hydrochar, are also discussed. This review summarizes the mechanism by which microplastics influence the performance of different types of sludge, and proposes effective strategies to mitigate the inhibitive effect of microplastics on sludge and discusses removal technologies of microplastics in sewage. Biochar and hydrochar are one of the effective measures to overcome the inhibition of microplastics on sludge. Meanwhile, constructed wetland may be one of the important choice for the future removal of microplastics from sewage. The goal is to provide theoretical support and insights for ensuring the stable operation of wastewater treatment plants and reducing the impact of microplastics on the environment.

Toxicological Profile of Polyethylene Terephthalate (PET) Microplastic in Ingested Drosophila melanogaster (Oregon R+) and Its Adverse Effect on Behavior and Development

Microplastics are readily available in the natural environment. Due to the pervasiveness of microplastic pollution, its effects on living organisms necessitate further investigation. The size, time of exposure, and amount of microplastic particles appear to be the most essential factor in determining their toxicological effects, either organismal or sub-organismal. For our research work, we preferred to work on a terrestrial model organism Drosophila melanogaster (Oregon R+). Therefore, in the present study, we characterized 2-100 µm size PET microplastic and confirmed its accumulation in Drosophila, which allowed us to proceed further in our research work. At larger dosages, research on locomotory activities such as climbing, jumping, and crawling indicated a decline in physiological and neuromuscular functions. Our studies also determined retarded development in flies and decreased survival rate in female flies after exposure to the highest concentration of microplastics. These experimental findings provide insight into the possible potential neurotoxic effects of microplastics and their detrimental effects on the development and growth of flies.

A critical review on nanoplastics and its future perspectives in the marine environment

Nanoplastics (plastic particles smaller than 1 μm) are the least-known type of marine litter. Nanoplastics (NPs) have attracted much interest in recent years because of their prevalence in the environment and the potential harm they can cause to living organisms. This article focuses on understanding NPs and their fate in the marine environment. Sources of NPs have been identified, including accidental release from products or through nano-fragmentation of larger plastic debris. As NPs have a high surface area, they may retain harmful compounds. The presence of harmful additives in NPs poses unique practical challenges for studies on their toxicity. In this review, several methods specifically adapted for the physical and chemical characterization of NPs have been discussed. Furthermore, the review provides an overview of the translocation and absorption of NPs into organisms, along with an evaluation of the release of potential toxins from NPs. Further, we have provided an overview about the existing methods suggested for the possible degradation of these NPs. We conclude that the hazards of NPs are plausible but unknown, necessitating a thorough examination of NPs' sources, fate, and effects to better mitigate and spread awareness about this emerging contaminant.

Microplastics perturb nitrogen removal, microbial community and metabolism mechanism in biofilm system

Microplastics (MPs) are a significant component of global pollution and cause widespread concern, particularly in wastewater treatment plants. While understanding the impact of MPs on nutrient removal and potential metabolism in biofilm systems is limited. This work investigated the impact of polystyrene (PS) and polyethylene terephthalate (PET) on the performance of biofilm systems. The results revealed that at concentrations of 100 and 1000 μg/L, both PS and PET had almost no effect on the removal of ammonia nitrogen, phosphorus, and chemical oxygen demand, but reduced the removal of total nitrogen by 7.40-16.6%. PS and PET caused cell and membrane damage, as evidenced by increases in reactive oxygen species and lactate dehydrogenase to 136-355% and 144-207% of the control group. Besides, metagenomic analysis demonstrated both PS and PET changed the microbial structure and caused functional differences. Some important genes in nitrite oxidation (e.g. nxrA), denitrification (e.g. narB, nirABD, norB, and nosZ), and electron production process (e.g. mqo, sdh, and mdh) were restrained, meanwhile, species contribution to nitrogen-conversion genes was altered, therefore disturbing nitrogen-conversion metabolism. This work contributes to evaluating the potential risks of biofilm systems exposed to PS and PET, maintaining high nitrogen removal and system stability.