Micro (nano) plastic pollution: The ecological influence on soil-plant system and human health

First insight of the intergenerational effects of tri-n-butyl phosphate and polystyrene microplastics to Daphnia magna

As an emerging organic pollutant, tributyl phosphate (TnBP) can be easily adsorbed by microplastics, resulting in compound toxic effects. In the present work, the effects of polystyrene microplastics (PS-MPs) and TnBP on the survival, growth, reproduction and oxidative stress of Daphnia magna (D. magna) have been evaluated through multigenerational test. Compared with the alone exposure groups, the somatic growth rate and the expression values of growth related genes rpa1, mre11, rnha, and rfc3_5 in the F1 generation of the combined exposure groups were significantly lower (p < 0.05), indicating synergistic effect of PS-MPs and TnBP on the growth toxicity and transgenerational effects. In addition, compared with the PS-MPs groups, significantly lower average number of offspring and expression values of reproduction related genes ccnb, mcm2, sgrap, and ptch1 were observed in the combined exposure group and TnBP group (p < 0.05), indicating TnBP might be the major factor causing reproductive toxicity to D. magna. Although PS-MPs and TnBP alone or in combination also had toxic impacts on the growth, survival and reproduction of D. magna in generations F0 and F2, the effects were less than F1 generation. Regarding oxidative stress, the activity of SOD, CAT and GSH-Px and MDA content in the generations F0 and F1 of combined exposure groups were higher than the TnBP group but lower than the PS-MPs groups, suggesting that PS-MPs might be the dominant cause of the oxidative damage in D. magna and the presence of TnBP would alleviate oxidative stress by reducing the bioaccumulation of PS-MPs. The present work will provide a theoretical basis for further understanding of the toxic effects and ecological risks of combined TnBP and microplastic pollution on aquatic organisms.

Review on personal protective equipment: Emerging concerns in micro(nano)plastic pollution and strategies for addressing environmental challenges

The COVID-19 pandemic was caused by the SARS-CoV-2 virus, marking one of the most catastrophic global health crises of the 21st century. Throughout this period, widespread use and improper disposal of personal protective equipment (PPE) emerged as a pressing environmental issue, significantly impacting various life forms. During the COVID-19 pandemic, there was a high rate of PEP disposal. An alarming 1.6 × 106 tons of plastic waste each day has been generated since the onset of the outbreak, predominantly from the inadequate disposal of PPE. The mismanagement and subsequent degradation of discarded PPE significantly contribute to increased non-biodegradable micro(nano)plastic (MNP) waste. This pollution has had profound adverse effects on terrestrial, marine, and aquatic ecosystems, which have been extensively of concern recently. Accumulated MNPs within aquatic organisms could serve as a potential route for human exposure when consuming seafood. This review presents a novel aspect concerning the pollution caused by MNPs, particularly remarking on their role during the pandemic and their detrimental effects on human health. These microplastic particles, through the process of fragmentation, transform into nanoparticles, persisting in the environment and posing potential hazards. The prevalence of MNP from PPE, notably masks, raises concerns about their plausible health risks, warranting global attention and comprehensive exploration. Conducting a comprehensive evaluation of the long-term effects of these processes and implementing effective management strategies is essential.

Polystyrene nanoplastics induce lipophagy via the AMPK/ULK1 pathway and block lipophagic flux leading to lipid accumulation in hepatocytes

Micro- and nanoplastic pollution has emerged as a significant global concern due to their extensive presence in the environment and potential adverse effects on human health. Nanoplastics can enter the human circulatory system and accumulate in the liver, disrupting hepatic metabolism and causing hepatotoxicity. However, the precise mechanism remains uncertain. Lipophagy is an alternative mechanism of lipid metabolism involving autophagy. This study aims to explore how polystyrene nanoplastics (PSNPs) influence lipid metabolism in hepatocytes via lipophagy. Initially, it was found that PSNPs were internalized by human hepatocytes, resulting in decreased cell viability. PSNPs were found to induce the accumulation of lipid droplets (LDs), with autophagy inhibition exacerbating this accumulation. Then, PSNPs were proved to activate lipophagy by recruiting LDs into autophagosomes and block the lipophagic flux by impairing lysosomal function, inhibiting LD degradation. Ultimately, PSNPs were shown to activate lipophagy through the AMPK/ULK1 pathway, and knocking down AMPK exacerbated lipid accumulation in hepatocytes. Overall, these results indicated that PSNPs triggered lipophagy via the AMPK/ULK1 pathway and blocked lipophagic flux, leading to lipid accumulation in hepatocytes. Thus, this study identifies a novel mechanism underlying nanoplastic-induced lipid accumulation, providing a foundation for the toxicity study and risk assessments of nanoplastics.

Nano- and microplastics drive the dynamic equilibrium of amoeba-associated bacteria and antibiotic resistance genes

As emerging pollutants, microplastics have become pervasive on a global scale, inflicting significant harm upon ecosystems. However, the impact of these microplastics on the symbiotic relationship between protists and bacteria remains poorly understood. In this study, we investigated the mechanisms through which nano- and microplastics of varying sizes and concentrations influence the amoeba-bacterial symbiotic system. The findings reveal that nano- and microplastics exert deleterious effects on the adaptability of the amoeba host, with the magnitude of these effects contingent upon particle size and concentration. Furthermore, nano- and microplastics disrupt the initial equilibrium in the symbiotic relationship between amoeba and bacteria, with nano-plastics demonstrating a reduced ability to colonize symbiotic bacteria within the amoeba host when compared to their microplastic counterparts. Moreover, nano- and microplastics enhance the relative abundance of antibiotic resistance genes and heavy metal resistance genes in the bacteria residing within the amoeba host, which undoubtedly increases the potential transmission risk of both human pathogens and resistance genes within the environment. In sum, the results presented herein provide a novel perspective and theoretical foundation for the study of interactions between microplastics and microbial symbiotic systems, along with the establishment of risk assessment systems for ecological environments and human health.

Full-chain analysis on emerging contaminants in soil: Source, migration and remediation

Emerging contaminants (ECs) are gaining attention due to their prevalence and potential negative impacts on the environment and human health. This paper provides a comprehensive review of the status and trends of soil pollution caused by ECs, focusing on their sources, migration pathways, and environmental implications. Significant ECs, including plastics, synthetic polymers, pharmaceuticals, personal care products, plasticizers, and flame retardants, are identified due to their widespread use and toxicity. Their presence in soil is attributed to agricultural activities, urban waste, and wastewater irrigation. The review explores both horizontal and vertical migration pathways, with factors such as soil type, organic matter content, and moisture levels influencing their distribution. Understanding the behavior of ECs in soil is critical to mitigating their long-term risks and developing effective soil remediation strategies. The paper also examines the advantages and disadvantages of in situ and ex situ treatment approaches for ECs, highlighting optimal physical, chemical, and biological treatment conditions. These findings provide a fundamental basis for addressing the challenges and governance of soil pollution induced by ECs.

Developments in the field of intestinal toxicity and signaling pathways associated with rodent exposure to micro(nano)plastics

The broad spread of micro(nano)plastics (MNPs) has garnered significant attention in recent years. MNPs have been detected in numerous human organs, indicating that they may also be hazardous to humans. The toxic effects of MNPs have been demonstrated in marine species and experimental animals. The primary pathway and target organ for MNPs entering the human body is the intestinal system, and increasing research has been done on the harmful effects and subsequent mechanisms of exposure to MNPs. Studies on how MNPs affect gut health in humans are scarce, nevertheless. Since rodents are frequently employed as animal models for human ailments, research on rodents exposed to MNPs can provide a more accurate representation of human circumstances. This study examined the effects of MNPs on intestinal microecology, inflammation, barrier function, and ion transport channels in rodents. It also reviewed the signal pathways involved, such as oxidative stress, nuclear factor (NF)-κB, Toll-like receptor (TLR) 4, inflammatory corpuscles, muscarinic acetylcholine receptors (mAChRs), mitogen-activated protein kinase (MAPK), and cell death. This review will offer a conceptual framework for the management and avoidance of associated illnesses.

Deficit irrigation of reclaimed water relieves oat drought stress while controlling the risk of PAEs pollution in microplastics-polluted soil

Reclaimed water irrigation has emerged as a critical alternative in agricultural regions facing water scarcity. However, soil pollution with microplastics (MPs) greatly increases the exposure risk and toxic effects of reclaimed water contaminations, such as phthalate esters (PAEs). A field experiment consisting of soil column pots evaluated the feasibility of using PAEs-contaminated water to irrigate oats (Avena sativa L.) in drought seasons. Three irrigation regimens based on soil matric potential thresholds (-10 kPa, -30 kPa, -50 kPa) explored the impact of PAE-contaminated water on oat physiology and environmental pollution in soil with and without MPs contamination. The results showed that treating oats at the SMP of -30 kPa boosted shoot biomass by 3.1%-14.0% compared to the drought condition at -50 kPa, and the root biomass of oats was significantly increased. The physiological metrics of oats indicated that irrigation at -50 kPa induced drought stress and oxidative damage in oats, particularly during the milk stage. Different irrigation treatments influenced the accumulation of PAEs in plants, soil, and leachate. The ratios of leachate to irrigation water in -10 kPa treatment with and without MPs addition were 1.18% and 4.48%, respectively, which aggravated the accumulation of pollutants in deep soil layers and may cause groundwater pollution. MPs pollution in soil increased the content of PAEs in the harvested oats and reduced the transport and accumulation of PAEs in deep soil layers (20-50 cm) and leachate. The coupling of PAEs in irrigation water with soil MPs pollution may exacerbate plant damage. However, the damage can be minimized under the scheduled irrigation at -30 kPa which could balance crop yield and potential risks.

Advances in plastic mycoremediation: Focus on the isoenzymes of the lignin degradation complex

This study investigates P. ostreatus and A. bisporus biodegradation capacity of low density polyethylene (LDPE) oxidised to simulate environmental weathering. Fourier transform infrared (FT-IR) spectroscopy and scanning electron microscopy (SEM) were used to analyse the degradation of LDPE treated with fungal cultures. Molecular implications of LDPE degradation by P. ostreatus and A. bisporus were evaluated by Reverse transcription followed by quantitative PCR (qRT-PCR) of lac, mnp and lip genes expression. After 90 days of incubation, FT-IR analysis showed, for both fungal treatments, an increasing in the intensity of peaks related to the asymmetric C-C-O stretching (1160 to 1000 cm-1) and the -OH stretching (3700 to 3200 cm-1) due to the formation of alcohols and carboxylic acid, indicating depolymerisation of LDPE. This was confirmed by the SEM analysis, where a widespread alteration of the surface morphology was observed for treated LDPE fragments. Results revealed that the exposure of P. ostreatus to oxidised LDPE treatment led to a significant increase in the expression of the lac6, lac7, lac9, lac10 and mnp2 genes, while A. bisporus showed an over-expression in lac2 and lac12 genes. The obtained results offer new perspectives for a biotechnological use of P. ostreatus and A. bisporus for plastic bioremediation.

Effect of various phosphorus levels on the extraction of Cd, the transformation of P, and phosphorus-related gene during the phytoremediation of Cd contaminated soil

Phytoremediation has emerged as a common technique for remediating Cd pollution in farmland soil. Moreover, phosphorus, an essential element for plants, can alter the pectin content of plant cell walls and facilitate the accumulation of Cd in plant tissues, thereby enhancing phytoremediation efficiency. Therefore, pot experiments were conducted in order to investigate the effect of phosphorus levels on Cd extraction, phosphorus transformation and phosphorus-related genes during phytoremediation. The results revealed that an optimal application of suitable phosphate fertilizers elevated the soil's pH and electrical conductivity (EC), facilitated the conversion of soil from insoluble phosphorus into available forms, augmented the release of pertinent enzyme activity, and induced the expression of phosphorus cycling-related genes. These enhancements in soil conditions significantly promoted the growth of ryegrass. When applying phosphorus at a rate of 600 mg/kg, ryegrass exhibited plant height, dry weight, and chlorophyll relative content that were 1.27, 1.26, and 1.18 times higher than those in the control group (P0), while the Cd content was 1.12 times greater than that of P0. The potentially toxic elements decline ratio and bioconcentration factor were 42.86% and 1.17 times higher than those of P0, respectively. Consequently, ryegrass demonstrated the highest Cd removal efficiency under these conditions. Results from redundancy analysis (RDA) revealed a significant correlation among pH, total phosphorus, heavy metal content, phosphorus forms, soil enzyme activity, and phosphorus-related genes. In conclusion, this study suggests applying an optimal amount of suitable phosphate fertilizers can enhance restoration efficiency, leading to a reduction in soil Cd content and ultimately improving the safety of crop production in farmlands.

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.

Temperature fluctuation in soil alters the nanoplastic sensitivity in wheat

Despite the wide acknowledgment that plastic pollution and global warming have become serious agricultural concerns, their combined impact on crop growth remains poorly understood. Given the unabated megatrend, a simulated soil warming (SWT, +4 °C) microcosm experiment was carried out to provide a better understanding of the effects of temperature fluctuations on wheat seedlings exposed to nanoplastics (NPs, 1 g L-1 61.71 ± 0.31 nm polystyrene). It was documented that SWT induced oxidative stress in wheat seedlings grown in NPs-contaminated soil, with an 85.56 % increase in root activity, while decreasing plant height, fresh weight, and leaf area by 8.72 %, 47.68 %, and 15.04 % respectively. The SWT also resulted in reduced photosynthetic electron-transfer reaction and Calvin-Benson cycle in NPs-treated plants. Under NPs, SWT stimulated the tricarboxylic acid (TCA) metabolism and bio-oxidation process. The decrease in photosynthesis and the increase in respiration resulted in an 11.94 % decrease in net photosynthetic rate (Pn). These results indicated the complicated interplay between climate change and nanoplastic pollution in crop growth and underscored the potential risk of nanoplastic pollution on crop production in the future climate.

Exploring Sustainable Agriculture with Nitrogen-Fixing Cyanobacteria and Nanotechnology

The symbiotic relationship between nitrogen-fixing cyanobacteria and plants offers a promising avenue for sustainable agricultural practices and environmental remediation. This review paper explores the molecular interactions between nitrogen-fixing cyanobacteria and nanoparticles, shedding light on their potential synergies in agricultural nanotechnology. Delving into the evolutionary history and specialized adaptations of cyanobacteria, this paper highlights their pivotal role in fixing atmospheric nitrogen, which is crucial for ecosystem productivity. The review discusses the unique characteristics of metal nanoparticles and their emerging applications in agriculture, including improved nutrient delivery, stress tolerance, and disease resistance. It delves into the complex mechanisms of nanoparticle entry into plant cells, intracellular transport, and localization, uncovering the impact on root-shoot translocation and systemic distribution. Furthermore, the paper elucidates cellular responses to nanoparticle exposure, emphasizing oxidative stress, signaling pathways, and enhanced nutrient uptake. The potential of metal nanoparticles as carriers of essential nutrients and their implications for nutrient-use efficiency and crop yield are also explored. Insights into the modulation of plant stress responses, disease resistance, and phytoremediation strategies demonstrate the multifaceted benefits of nanoparticles in agriculture. Current trends, prospects, and challenges in agricultural nanotechnology are discussed, underscoring the need for responsible and safe nanoparticle utilization. By harnessing the power of nitrogen-fixing cyanobacteria and leveraging the unique attributes of nanoparticles, this review paves the way for innovative, sustainable, and efficient agricultural practices.

Adsorption of PFAS onto secondary microplastics: A mechanistic study

Microplastics (MPs) are abundant in aquatic systems. The ecological risks of MPs may arise from their physical features, chemical properties, and/or their ability to concentrate and transport other contaminants, such as per- and polyfluoroalkyl substances (PFAS). PFAS have been extracted from MPs found in natural waters. Still, there needs to be a mechanistic investigation of the effect of PFAS chemistry and water physicochemical properties on how PFAS partition onto secondary MPs. Here, we studied the influence of pH, natural organic matter (NOM), ionic strength, and temperature on the adsorption of PFAS on MPs generated from PET water bottles. The adsorption of PFAS to the MPs was thermodynamically spontaneous at 25 °C, based on Gibb's free energy (ΔG = -16 to -23 kJ/mol), primarily due to increased entropy after adsorption. Adsorption reached equilibrium within 7-9 h. Hence, PFAS will partition to the surface of secondary PET MPs within hours in fresh and saline waters. Natural organic matter decreased the capacity of secondary PET MPs for PFAS through electrosteric repulsion, while higher ionic strength favored PFAS adsorption by decreasing electrostatic repulsion. Increased pH increased electrostatic repulsion, which negated PFAS adsorption. The study provides fundamental information for developing models to predict interactions between secondary MPs and PFAS.

Unveiling the detrimental effects of polylactic acid microplastics on rice seedlings and soil health

The environmental impact of biodegradable polylactic acid microplastics (PLA-MPs) has become a global concern, with documented effects on soil health, nutrient cycling, water retention, and crop growth. This study aimed to assess the repercussions of varying concentrations of PLA-MPs on rice, encompassing aspects such as growth, physiology, and biochemistry. Additionally, the investigation delved into the influence of PLA-MPs on soil bacterial composition and soil enzyme activities. The results illustrated that the highest levels of PLA-MPs (2.5%) impaired the photosynthesis activity of rice plants and hampered plant growth. Plants exposed to the highest concentration of PLA-MPs (2.5%) displayed a significant reduction of 51.3% and 47.7% in their root and shoot dry weights, as well as a reduction of 53% and 49% in chlorophyll a and b contents, respectively. The activities of catalase (CAT), superoxide dismutase (SOD), peroxidase (POD), and ascorbate peroxidase (APX) in rice leaves increased by 3.1, 2.8, 3.5, and 5.2 folds, respectively, with the highest level of PLA-MPs (2.5%). Soil enzyme activities, such as CAT, urease, and dehydrogenase (DHA) increased by 19.2%, 10.4%, and 22.5%, respectively, in response to the highest level of PLA-MPs (2.5%) application. In addition, PLA-MPs (2.5%) resulted in a remarkable increase in the relative abundance of soil Proteobacteria, Nitrospirae, and Firmicutes by 60%, 31%, and 98.2%, respectively. These findings highlight the potential adverse effects of PLA-MPs on crops and soils. This study provides valuable insights into soil-rice interactions, environmental risks, and biodegradable plastic regulation, underscoring the need for further research.

Solar light photodegradation of nicotine in the presence of aged polystyrene microplastics

Limited information exists on the potential of aged microplastics to induce photodegradation of organic pollutants under sunlight irradiation. In this work, nicotine (NIC), a widespread emerging contaminant, was used as a model organic substrate to investigate this innovative degradation process. Polystyrene (PS) pellets were artificially aged and became rich in oxygenated moieties with their carbonyl index reaching 0.43 ± 0.04 after 4 d of aging. The degradation of NIC photosensitized by aged PS at different pH values was monitored for 6 h under simulated sunlight irradiation (650 W/m2). The maximum degradation rate was observed at pH = 11 (75 % NIC removal from a 10 mg L-1 solution containing 50 g L-1 aged PS pellets), suggesting that the unprotonated NIC is the most photoreactive form. Increasing the PS load from 50 to 200 g L-1 accelerated NIC degradation. The addition of 2.5 mg L-1 humic acids had a slight enhancement role (82 % NIC degradation), which confirms their effectiveness as photosensitizers. NIC photosensitization by aged PS was also studied in the presence of t-butanol (55 % NIC removal in solutions containing 100 mg L-1 t-butanol) and in anoxic conditions (NIC solution purged with N2; 95 % NIC removal), to gain insight into the respective roles of the potentially formed •OH and 1O2. The main photo-produced reactive species involved in NIC degradation likely were the triplet states of the PS beads (3PS*). Differently from most advanced oxidation processes, NIC's photodegradation by aged PS was not affected by increasing amount of chloride and we observed negligible differences between NIC degradation in ultra-pure water and seawater. The effectiveness of irradiated PS towards NIC photodegradation was also investigated in tap water and secondary wastewater. Overall, the possibility to decontaminate polluted water with waste-derived materials is interesting in the framework of circular economy.

Analysis of micro(nano)plastics based on automated data interpretation and modeling: A review

The widespread presence of micro(nano)plastics (MNPs) in the environment threatens ecosystem integrity, and thus, it is necessary to determine and assess the occurrence, characteristics, and transport of MNPs between ecological components. However, most analytical approaches are cost- and time-inefficient in providing quantitative information with sufficient detail, and interpreting results can be difficult. Alternative analyses integrating novel measurements by imaging or proximal sensing with signal processing and machine learning may supplement these approaches. In this review, we examined published research on methods used for the automated data interpretation of MNPs found in the environment or those artificially prepared by fragmenting bulk plastics. We critically reviewed the primary areas of the integrated analytical process, which include sampling, data acquisition, processing, and modeling, applied in identifying, classifying, and quantifying MNPs in soil, sediment, water, and biological samples. We also provide a comprehensive discussion regarding model uncertainties related to estimating MNPs in the environment. In the future, the development of routinely applicable and efficient methods is expected to significantly contribute to the successful establishment of automated MNP monitoring systems.

Micro(nano)plastics in human urine: A surprising contrast between Chongqing's urban and rural regions

Microplastics (100 nm-5 mm) and nanoplastics (<100 nm) collectively referred to as micro(nano)plastics (MNPs), which are emerging pollutants all over the world. Environmental differences affect its distribution. The content of MNPs differs between urban and rural environments, according to previous studies. To understand the actual situation of human exposure to MNPs in various environments, this study collected 12 urine samples from volunteers in urban and rural regions of Chongqing and used pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) and laser direct infrared spectroscopy (LDIR) to detect and analyze MNPs in urine. With an average abundance of 1.50 (2.31) mg/kg, MNPs were found in 9 samples by Py-GC/MS. Polyethylene (PE), polyvinyl chloride (PVC) and polyamide 66 (PA66), three different types of MNPs were found, with PE content being the highest among them. By using LDIR, MNPs were found in 7 samples, with an average abundance of 15.17 (23.13) particles/kg. Five different types of MNPs were found, with acrylates (ACR) being the main type, followed by polymethylmethacrylate (PMMA), polyurethane (PU), polypropylene (PP), polyethylene terephthalate (PET). The findings demonstrated that urban region had much greater levels and more types of MNPs in human urine than rural. Additionally, regular contact with plastic toys and the use of personal care products are linked to the presence of MNPs. The influence of environmental factors on the actual exposure of the human body to MNPs was preliminary explored in this study, and two different methods were used for the first time to simultaneously detect and analyze MNPs in human urine. This allowed for the feasibility of comprehensively and effectively quantitatively analyzing the actual exposure of the human body to MNPs, and also provided the theoretical foundation for further research on the harm of MNPs to human health in different environments.

Recent advances in nanotechnology-based modifications of micro/nano PET plastics for green energy applications

Poly(ethylene terephthalate) (PET) plastic is an omnipresent synthetic polymer in our lives, which causes negative impacts on the ecosystem. It is crucial to take mandatory action to control the usage and sustainable disposal of PET plastics. Recycling plastics using nanotechnology offers potential solutions to the challenges associated with traditional plastic recycling methods. Nano-based degradation techniques improve the degradation process through the influence of catalysts. It also plays a crucial role in enhancing the efficiency and effectiveness of recycling processes and modifying them into value-added products. The modified PET waste plastics can be utilized to manufacture batteries, supercapacitors, sensors, and so on. The waste PET modification methods have massive potential for research, which can play major role in removing post-consumer plastic waste. The present review discusses the effects of micro/nano plastics in terrestrial and marine ecosystems and its impacts on plants and animals. Briefly, the degradation and bio-degradation methods in recent research were explored. The depolymerization methods used for the production of monomers from PET waste plastics were discussed in detail. Carbon nanotubes, fullerene, and graphene nanosheets synthesized from PET waste plastics were delineated. The reuse of nanotechnologically modified PET waste plastics for potential green energy storage products, such as batteries, supercapacitors, and sensors were presented in this review.

Science-based evidence on pathways and effects of human exposure to micro- and nanoplastics

Human exposure to plastic particles has raised great concern among all relevant stakeholders involved in the protection of human health due to the contamination of the food chain, surface waters, and even drinking water as well as due to their persistence and bioaccumulation. Now more than ever, it is critical that we understand the biological fate of plastics and their interaction with different biological systems. Because of the ubiquity of plastic materials in the environment and their toxic potential, it is imperative to gain reliable, regulatory-relevant, science-based data on the effects of plastic micro- and nanoparticles (PMNPs) on human health in order to implement reliable risk assessment and management strategies in the circular economy of plastics. This review presents current knowledge of human-relevant PMNP exposure doses, pathways, and toxic effects. It addresses difficulties in properly assessing plastic exposure and current knowledge gaps and proposes steps that can be taken to underpin health risk perception, assessment, and mitigation through rigorous science-based evidence. Based on the existing scientific data on PMNP adverse health effects, this review brings recommendations on the development of PMNP-specific adverse outcome pathways (AOPs) following the AOP Users' Handbook of the Organisation for Economic Cooperation and Development (OECD).

Microplastic release and sulfate reduction response in the early stage of a simulated landfill

Landfills are essential facilities for treating and disposing municipal solid waste. They emit sulfur-containing odors and serve as an important sink for a new type of pollutant called microplastics (MPs). This study focused on the initial stage of anaerobic degradation to establish the relationship between the release of MPs and odor generation. Our findings show the rapid release of MPs into the leachate in the early stage of landfill and their predominant accumulation in the leachate sediment. The circulating leachate contained 1.45 times higher concentrations of MPs than the noncirculating leachate, with a peak concentration of 39 items·L-1. In addition, fragmentation of MPs occurred. The percentage of MPs with particle sizes of 2.5-5 mm decreased from 66.70 % to 22.32 %, while those measuring 0.1-0.5 mm increased by 33.12 %. A positive correlation was observed between MP release and sulfate reduction. Although leachate circulation increased the release of MPs, it also reduced the overall release time and total amount of MPs exported from the landfill. Compared with the initial landfill waste, the leachate operation mode, regardless of circulation, resulted in a 6.15-8.93-fold increase in MP release. These findings provide a valuable foundation for the simultaneous regulation of traditional pollutant odor and new pollutants (MPs) in landfills.

Composting municipal solid waste and animal manure in response to the current fertilizer crisis - a recent review

The dynamic price increases of fertilizers and the generation of organic waste are currently global issues. The growth of the population has led to increased production of solid municipal waste and a higher demand for food. Food production is inherently related to agriculture and, to achieve higher yields, it is necessary to replenish the soil with essential minerals. A synergistic approach that addresses both problems is the implementation of the composting process, which aligns with the principles of a circular economy. Food waste, green waste, paper waste, cardboard waste, and animal manure are promising feedstock materials for the extraction of valuable compounds. This review discusses key factors that influence the composting process and compares them with the input materials' parameters. It also considers methods for optimizing the process, such as the use of biochar and inoculation, which result in the production of the final product in a significantly shorter time and at lower financial costs. The applications of composts produced from various materials are described along with associated risks. In addition, innovative composting technologies are presented.

Ototoxicity of polystyrene nanoplastics in mice, HEI-OC1 cells and zebrafish

Polystyrene nanoplastics are a novel class of pollutants. They are easily absorbed by living organisms, and their potential toxicity has raised concerns. However, the impact of polystyrene nanoplastics on auditory organs remains unknown. Here, our results showed that polystyrene nanoplastics entered the cochlea of mice, HEI-OC1 cells, and lateral line hair cells of zebrafish, causing cellular injury and increasing apoptosis. Additionally, we found that exposure to polystyrene nanoplastics resulted in a significant elevation in the auditory brainstem response thresholds, a loss of auditory sensory hair cells, stereocilia degeneration and a decrease in expression of Claudin-5 and Occludin proteins at the blood-lymphatic barrier in mice. We also observed a significant decrease in the acoustic alarm response of zebrafish after exposure to polystyrene nanoplastics. Mechanistic analysis revealed that polystyrene nanoplastics induced up-regulation of the Nrf2/HO-1 pathway, increased levels of malondialdehyde, and decreased superoxide dismutase and catalase levels in cochlea and HEI-OC1 cells. Furthermore, we observed that the expression of ferroptosis-related indicators GPX4 and SLC7A11 decreased as well as increased expression of ACLS4 in cochlea and HEI-OC1 cells. This study also revealed that polystyrene nanoplastics exposure led to increased expression of the inflammatory factors TNF-α, IL-1β and COX2 in cochlea and HEI-OC1 cells. Further research found that the cell apoptosis, ferroptosis and inflammatory reactions induced by polystyrene nanoplastics in HEI-OC1 cells was reversed through the pretreatment with N-acetylcysteine, a reactive oxygen species inhibitor. Overall, our study first discovered and systematically revealed the ototoxicity of polystyrene nanoplastics and its underlying mechanism.

A comprehensive review on the source, ingestion route, attachment and toxicity of microplastics/nanoplastics in human systems

Microplastics (MPs)/nanoplastics (NPs) are widely found in the natural environment, including soil, water and the atmosphere, which are essential for human survival. In the recent years, there has been a growing concern about the potential impact of MPs/NPs on human health. Due to the increasing interest in this research and the limited number of studies related to the health effects of MPs/NPs on humans, it is necessary to conduct a systematic assessment and review of their potentially toxic effects on human organs and tissues. Humans can be exposed to microplastics through ingestion, inhalation and dermal contact, however, ingestion and inhalation are considered as the primary routes. The ingested MPs/NPs mainly consist of plastic particles with a particle size ranging from 0.1 to 1 μm, that distribute across various tissues and organs within the body, which in turn have a certain impact on the nine major systems of the human body, especially the digestive system and respiratory system, which are closely related to the intake pathway of MPs/NPs. The harmful effects caused by MPs/NPs primarily occur through potential toxic mechanisms such as induction of oxidative stress, generation of inflammatory responses, alteration of lipid metabolism or energy metabolism or expression of related functional factors. This review can help people to systematically understand the hazards of MPs/NPs and related toxicity mechanisms from the level of nine biological systems. It allows MPs/NPs pollution to be emphasized, and it is also hoped that research on their toxic effects will be strengthened in the future.

Assessment of Kaistella jeonii esterase conformational dynamics in response to poly(ethylene terephthalate) binding

The pervasive presence of plastic in the environment has reached a concerning scale, being identified in many ecosystems. Bioremediation is the cheapest and most eco-friendly alternative to remove this polymer from affected areas. Recent work described that a novel cold-active esterase enzyme extracted from the bacteria Kaistella jeonii could promiscuously degrade PET. Compared to the well-known PETase from Ideonella sakaiensis, this novel esterase presents a low sequence identity yet has a remarkably similar folding. However, enzymatic assays demonstrated a lower catalytic efficiency. In this work, we employed a strict computational approach to investigate the binding mechanism between the esterase and PET. Understanding the underlying mechanism of binding can shed light on the evolutive mechanism of how enzymes have been evolving to degrade these artificial molecules and help develop rational engineering approaches to improve PETase-like enzymes. Our results indicate that this esterase misses a disulfide bridge, keeping the catalytic residues closer and possibly influencing its catalytic efficiency. Moreover, we describe the structural response to the interaction between enzyme and PET, indicating local and global effects. Our results aid in deepening the knowledge behind the mechanism of biological catalysis of PET degradation and as a base for the engineering of novel PETases.

Photo-oxidation of Micro- and Nanoplastics: Physical, Chemical, and Biological Effects in Environments

Micro- and nanoplastics (MNPs) are attracting increasing attention due to their persistence and potential ecological risks. This review critically summarizes the effects of photo-oxidation on the physical, chemical, and biological behaviors of MNPs in aquatic and terrestrial environments. The core of this paper explores how photo-oxidation-induced surface property changes in MNPs affect their adsorption toward contaminants, the stability and mobility of MNPs in water and porous media, as well as the transport of pollutants such as organic pollutants (OPs) and heavy metals (HMs). It then reviews the photochemical processes of MNPs with coexisting constituents, highlighting critical factors affecting the photo-oxidation of MNPs, and the contribution of MNPs to the phototransformation of other contaminants. The distinct biological effects and mechanism of aged MNPs are pointed out, in terms of the toxicity to aquatic organisms, biofilm formation, planktonic microbial growth, and soil and sediment microbial community and function. Furthermore, the research gaps and perspectives are put forward, regarding the underlying interaction mechanisms of MNPs with coexisting natural constituents and pollutants under photo-oxidation conditions, the combined effects of photo-oxidation and natural constituents on the fate of MNPs, and the microbiological effect of photoaged MNPs, especially the biotransformation of pollutants.

A comprehensive review of micro- and nano-plastics in the atmosphere: Occurrence, fate, toxicity, and strategies for risk reduction

Micro- and nano-plastics (MNPs) have received considerable attention over the past 10 years due to their environmental prevalence and potential toxic effects. With the increase in global plastic production and disposal, MNP pollution has become a topic of emerging concern. In this review, we describe MNPs in the atmospheric environment, and potential toxicological effects of exposure to MNPs. Studies have reported the occurrence of MNPs in outdoor and indoor air at concentrations ranging from 0.0065 items m-3 to 1583 items m-3. Findings have identified plastic fragments, fibers, and films in sizes predominantly <1000 μm with polyamide (PA), polyester (PES), polyethylene terephthalate (PET), polypropylene (PP), rayon, polyethylene (PE), polystyrene (PS), polyvinyl chloride (PVC), polyacrylonitrile (PAN), and ethyl vinyl acetate (EVA) as the major compounds. Exposure through indoor air and dust is an important pathway for humans. Airborne MNPs pose health risks to plants, animals, and humans. Atmospheric MNPs can enter organism bodies via inhalation and subsequent deposition in the lungs, which triggers inflammation and other adverse health effects. MNPs could be eliminated through source reduction, policy/regulation, environmental awareness and education, biodegradable materials, bioremediation, and efficient air-filtration systems. To achieve a sustainable society, it is crucial to implement effective strategies for reducing the usage of single-use plastics (SUPs). Further, governments play a pivotal role in addressing the pressing issue of MNPs pollution and must establish viable solutions to tackle this significant challenge.

Research progress on the cellular toxicity caused by microplastics and nanoplastics

Microplastics (MPs) are plastic particles of a diameter of less than 5 mm and a major carrier of pollution. In accordance with its diameter range, MPs can be divided into microplastics (100-5 mm) and nanoplastics (<100 nm). In recent years, in addition to the impact of MPs on the environment, the ways in which MPs affect the body has also attracted continuous attention. However, relevant studies on the cytotoxicity of MPs are not comprehensive. Based on the current research, this paper summarizes four main cytotoxic mechanisms of MPs, inducing oxidative stress, damaging cell membrane organelles, inducing immune response, and genotoxicity. Generally, MPs cause cytotoxicity such as oxidative stress, damage to cell membranes and organelles, activation of immune responses, and genotoxicity through mechanical damage or induction of cells to produce reactive oxygen species. Understanding these toxic mechanisms is helpful for the evaluation and prevention of human toxicity of MPs. This paper also analyzes the limitations of current research and prospects for future research into cellular MPs, with the aim of providing a scientific basis and reference for further research into the toxic mechanism of MPs.

Analytical challenges in detecting microplastics and nanoplastics in soil-plant systems

Microplastics (MPx) and nanoplastics (NPx) are increasingly accumulating in terrestrial ecosystems, heightening concerns about their potential adverse effects on human health via the food chain. Techniques aimed at recovering the most challenging colloidal fractions of MPx and NPx, especially for analytical purposes, are limited. This systematic review emphasises the absence of a universal, efficient, and cost-effective analytical method as the primary hindrance to studying MPx and NPx in soil and plant samples. The study reveals that several methods, including density separation, organic matter removal, and filtration, are utilized to detect MPx or NPx in soil through vibrational spectroscopy and visual identification. Instruments such as Pyrolysis Gas Chromatography Mass Spectrometry (Py-GCMS), Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), Fourier Transform Infrared (FTIR) Spectroscopy, and fluorescence microscopy are employed to identify MPx and NPx in plant tissue. In extraction procedures, organic solvents and sonication are used to isolate NPx from plant tissues, while Pyrolysis GC-MS quantifies the plastics. SEM and TEM serve to observe and characterize NPx within plant tissues. Additionally, FTIR and fluorescence microscopy are utilized to identify polymers of MPx and NPx based on their spectral characteristics and fluorescence signals. The findings from this review clarify the identification and quantification methods for MPx and NPx in soil and plant systems and provide a comprehensive methodology for assessing MPx/NPx in the environment.

Comprehensive analysis of nanoplastic effects on growth phenotype, nanoplastic accumulation, oxidative stress response, gene expression, and metabolite accumulation in multiple strawberry cultivars

Nanoplastics (NPs) have emerged as a novel environmental threat due to their potential impacts on both animals and plants. Currently, research on the ecotoxicity of NPs has mainly focused on marine aquatic organisms and freshwater algae, with very limited investigations conducted on horticultural plants. This study examined the effects of varying concentrations (0, 1, 10, 50 mg·L-1) of polystyrene NPs (PS-NPs) on strawberry growth. The findings revealed that low concentrations of PS-NPs stimulated strawberry growth, whereas high concentrations impeded it. Notably, diverse strawberry cultivars displayed considerable differences in their sensitivity to PS-NP exposure. Laser scanning confocal microscopy confirmed the absorption of PS-NPs by strawberry roots, with variations in PS-NP accumulation observed across different cultivars. Comparative transcriptomics analysis suggested that the differential expression of genes responsible for calcium ion transport played a significant role in the observed intervarietal differences in PS-NP accumulation among strawberry cultivars. Furthermore, distinct variations in endogenous oxidative responses were observed in different strawberry cultivars under PS-NP treatment. Further analysis indicated that the down-regulation of peroxidase (POD) gene expression and terpenoid compounds accumulation were responsible for heightened endogenous oxidative stress observed in certain strawberry cultivars under PS-NP treatment. Transcriptomic and metabolomic analyses were performed on six strawberry cultivars to investigate their response to PS-NPs in terms of endogenous gene expression and metabolite accumulation. The results identified one commonly up-regulated gene (wall-associated receptor kinase-like) and sixteen commonly down-regulated genes associated with lipid metabolism and carbohydrate metabolism. In addition, a significant reduction in fatty acid metabolite accumulation was observed in the six strawberry cultivars under PS-NP treatment. These findings have significant implications for understanding the effects of NPs on strawberry growth, metabolism, and antioxidant responses, as well as identifying marker genes for monitoring and evaluating the impact of NP pollution on strawberry.

Impacts of polypropylene microplastics on lipid profiles of mouse liver uncovered by lipidomics analysis and Raman spectroscopy

Microplastics (MPs) are emerging contaminants, and there are only limited studies reporting the impacts of some MPs on liver lipid metabolism in animals. In this study, we investigated the accumulation of polypropylene-MPs in mouse liver and unraveled the change in lipid metabolic profiles by both lipidomics and Raman spectroscopy. Polypropylene-MP exposure did not cause obvious health symptoms, but hematoxylin-eosin staining showed pathological changes that polypropylene-MPs induced lipid droplet accumulation in liver. Lipidomics results showed a significant change in lipid metabolic profiles and the most influenced categories were triglycerides, fatty acids, free fatty acids and lysophosphatidylcholine, implying the effects of polypropylene-MPs on the hemostasis of lipid droplet biogenesis and catabolism. Most altered lipids contained unsaturated bonds and polyunsaturated phospholipids, possibly affecting the fluidity and curvature of membrane surfaces. Raman spectroscopy confirmed that the major spectral alterations of liver tissues were related to lipids, evidencing the altered lipid metabolism and cell membrane components in the presence of polypropylene-MPs. Our findings firstly disclosed the impacts of polypropylene-MPs on lipid metabolisms in mouse liver and hinted at their detrimental disturbance on membrane properties, cellular lipid storage and oxidation regulation, helping our deeper understanding on the toxicities and corresponding risks of polypropylene-MPs to mammals.

Health risk assessment and bioaccumulation of potentially toxic metals from water, soil, and forages near coal mines of district Chakwal, Punjab, Pakistan

Water, forages, and soil contamination with potentially toxic metals (PTMs) through anthropogenic activities has become a significant environmental concern. It is crucial to find out the level of PTMs in water, soil, and forages near industrial areas. The PTMs enter the body of living organisms through these sources and have become a potential risk for humans and animals. Therefore, the present study aims at the health risk assessment of PTMs and their accumulation in soil, water, and forages of three tehsils (Kallar Kahar, Choa Saidan Shah, and Chakwal) in district Chakwal. Samples of wastewater, soil, and forages were collected from various sites of district Chakwal. PTMs detected in the present study were cadmium (Cd), chromium (Cr), lead (Pb), zinc (Zn), cobalt (Co), copper (Cu), and nickel (Ni), and their levels were measured through atomic absorption spectrophotometer (AAs GF95 graphite furnace auto sampler). Pollution load index (PLI), bio concentration factor (BCF), soil enrichment factors (EF), daily intake value (DIM), and health risk index (HRI) in sheep, cow, and buffalo were also analyzed. The results revealed that the mean concentration (mg/L) of Cd (0.72-0.91 mg/L), Cr (1.84-2.23 mg/L), Pb (0.95-3.22 mg/L), Co (0.74-2.93 mg/L), Cu (0.84-1.96 mg/L), and Ni (1.39-4.39 mg/L) in wastewater samples was higher than permissible limits set by WHO, NEQS, WWF, USEPA, and Pakistan in all three tehsils of district Chakwal. Similarly, in soil samples, concentrations of Cd (1.21-1.95 mg/kg), Cr (38.1-56.4 mg/kg), and Ni (28.3-55.9 mg/kg) were higher than their respective threshold values. The mean concentration of PTMs in forage samples (Parthenium hysterophorus, Mentha spicata, Justicia adhatoda, Calotropis procera, Xanthium strumarium, Amaranthaceae sp.) showed that maximum values of Cd (5.35-7.55 mg/kg), Cr (5.47-7.51 mg/kg), Pb (30-36 mg/kg), and Ni (12.6-57.5 mg/kg) were beyond their safe limit set for forages. PLI, BCF, and EF were > 1.0 for almost all the PTMs. The DIM and HRI for sheep were less than < 1.0 but for cows and buffalo were > 1.0. The current study showed that soil, water, and forages near coal mines area are contaminated with PTMs which enter the food chain and pose significant harm to humans and animals. In order to prevent their dangerous concentration in the food chain, regular assessment of PTMs present in soil, forages, irrigating water, and food is recommended.

A Deep-Sea Bacterium Is Capable of Degrading Polyurethane

Plastic wastes have been recognized as the most common and durable marine contaminants, which are not only found in the shallow water, but also on the sea floor. However, whether deep-sea microorganisms have evolved the capability of degrading plastic remains elusive. In this study, a deep-sea bacterium Bacillus velezensis GUIA was found to be capable of degrading waterborne polyurethane. Transcriptomic analysis showed that the supplement of waterborne polyurethane upregulated the expression of many genes related to spore germination, indicating that the presence of plastic had effects on the growth of strain GUIA. In addition, the supplement of waterborne polyurethane also evidently upregulated the expressions of many genes encoding lipase, protease, and oxidoreductase. Liquid chromatography-mass spectrometry (LC-MS) results showed that potential enzymes responsible for plastic degradation in strain GUIA were identified as oxidoreductase, protease, and lipase, which was consistent with the transcriptomic analysis. In combination of in vitro expression and degradation assays as well as Fourier transform infrared (FTIR) analysis, we demonstrated that the oxidoreductase Oxr-1 of strain GUIA was the key degradation enzyme toward waterborne polyurethane. Moreover, the oxidoreductase Oxr-1 was also shown to degrade the biodegradable polybutylene adipate terephthalate (PBAT) film indicating its wide application potential. IMPORTANCE The widespread and indiscriminate disposal of plastics inevitably leads to environmental pollution. The secondary pollution by current landfill and incineration methods causes serious damage to the atmosphere, land, and rivers. Therefore, microbial degradation is an ideal way to solve plastic pollution. Recently, the marine environment is becoming a hot spot to screen microorganisms possessing potential plastic degradation capabilities. In this study, a deep-sea Bacillus strain was shown to degrade both waterborne polyurethane and biodegradable PBAT film. The FAD-binding oxidoreductase Oxr-1 was demonstrated to be the key enzyme mediating plastic degradation. Our study not only provided a good candidate for developing bio-products toward plastic degradation but also paved a way to investigate the carbon cycle mediated by plastic degradation in deep-sea microorganisms.

Environmental impacts of microplastic and role of plastisphere microbes in the biodegradation and upcycling of microplastic

Increasing usage of plastic has led to the deposition of plastic in the environment which later become microplastic, a pollutant of global concern. These polymeric particles affect the ecosystem bestowing toxicity and impede the biogeochemical cycles. Besides, microplastic particles have been known for their role in aggravating the effect of various other environmental pollutants including organic pollutants and heavy metals. These microplastic surfaces are often colonized by the microbial communities also known as "plastisphere microbes" forming biofilms. These microbes include cyanobacteria like Nostoc, Scytonema, etc., and diatoms like Navicula, Cyclotella, etc. Which become the primary colonizer. In addition to the autotrophic microbes, Gammaproteobacteria and Alphaproteobacteria dominate the plastisphere microbial community. These biofilm-forming microbes can efficiently degrade the microplastic in the environment by secreting various catabolic enzymes such as lipase, esterase, hydroxylase, etc. Besides, these microbes have shown great potential for the bioconversion of microplastic to polyhydroxyalkanoates (PHA), an energy efficient and sustainable alternative to the petroleum based plastics. Thus, these microbes can be used for the creation of a circular economy using waste to wealth strategy. This review provides a deeper insight into the distribution, transportation, transformation, and biodegradation of microplastic in the ecosystem. The formation of plastisphere by the biofilm-forming microbes has been described in the article. In addition, the microbial metabolic pathways and genetic regulations involved in the biodegradation have been discussed in detail. The article suggests the microbial bioremediation and upcycling of microplastic along with various other strategies for effectively mitigate the microplastic pollution.

A review on mechanistic understanding of microplastic pollution on the performance of anaerobic digestion

Anaerobic digestion (AD) has emerged as a promising technology for diverting the organic waste from the landfills along with the production of clean energy. AD is a microbial-driven biochemical process wherein the plethora of microbial communities participate in converting the putrescible organic matter into biogas. Nevertheless, the AD process is susceptible to the external environmental factors such as presence of physical (microplastics) and chemical (antibiotics, pesticides) pollutants. The microplastics (MPs) pollution has received recent attention due to the increasing plastic pollution in terrestrial ecosystems. This review was aimed for holistic assessment of impact of MPs pollution on AD process to develop efficient treatment technology. First, the possible pathways of MPs entry into the AD systems were critically evaluated. Further, the recent literature on the experimental studies pertaining to the impact of different types of MPs at different concentrations on the AD process was reviewed. In addition, several mechanisms such as direct exposure of MPs on the microbial cells, indirect impact of MPs through the leaching of toxic chemicals and reactive oxygen species (ROS) formation on AD process were elucidated. Besides, the risk possessed by the increase of antibiotic resistance genes (ARGs) after the AD process due to the MPs stress on microbial communities were discussed. Overall, this review deciphered the severity of MPs pollution on AD process at different levels.

Microplastics in soils during the COVID-19 pandemic: Sources, migration and transformations, and remediation technologies

The COVID-19 pandemic has led to a notable upsurge of 5-10 % in global plastic production, which could have potential implications on the soil quality through increased microplastics (MPs) content. The elevated levels of MPs in the soil poses a significant threat to both the environment and human health, hence necessitating the remediation of MPs in the environment. Despite the significant attention given to MPs remediation in aqueous environments, less consideration has been given to MPs remediation in the soil. Consequently, this review highlights the major sources of MPs in the soil, their migration and transformation behaviors during the COVID-19 pandemic, and emphasizes the importance of utilizing remediation technologies such as phytoremediation, thermal treatment, microbial degradation, and photodegradation for MPs in the soil. Furthermore, this review provides a prospective outlook on potential future remediation methods for MPs in the soil. Although the COVID-19 pandemic is nearing its end, the long-term impact of MPs on the soil remains, making this review a valuable reference for the remediation of MPs in the post-pandemic soil.

Post-pandemic micro/nanoplastic pollution: Toward a sustainable management

The global health crisis caused by the COVID-19 pandemic has resulted in massive plastic pollution from the use of personal protection equipment (PPE), with polypropylene (PP) being a major component. Owing to the weathering of exposed PPEs, such contamination causes microplastic (MP) and nanoplastic (NP) pollution and is extremely likely to act as a vector for the transportation of COVID-19 from one area to another. Thus, a post-pandemic scenario can forecast with certainty that a significant amount of plastic garbage combined with MP/NP formation has an adverse effect on the ecosystem. Therefore, updating traditional waste management practices, such as landfilling and incineration, is essential for making plastic waste management sustainable to avert this looming catastrophe. This study investigates the post-pandemic scenario of MP/NP pollution and provides an outlook on an integrated approach to the recycling of PP-based plastic wastes. The recovery of crude oil, solid char, hydrocarbon gases, and construction materials by approximately 75, 33, 55, and 2 %, respectively, could be achieved in an environmentally friendly and cost-effective manner. Furthermore, the development of biodegradable and self-sanitizing smart PPEs has been identified as a promising alternative for drastically reducing plastic pollution.

Impact of Microplastics and Nanoplastics on Livestock Health: An Emerging Risk for Reproductive Efficiency

Pollution due to microplastics and nanoplastics is one of the major environmental issues of the last decade and represents a growing threat to human and animal health. In aquatic species, there is a large amount of information regarding the perturbation of marine organisms; instead, there are only a few studies focusing on the pathophysiological consequences of an acute and chronic exposure to micro- and nanoplastics in mammalian systems, especially on the reproductive system. There are several studies that have described the damage caused by plastic particles, including oxidative stress, apoptosis, inflammatory response, dysregulation of the endocrine system and accumulation in various organs. In addition to this, microplastics have recently been found to influence the evolution of microbial communities and increase the gene exchange, including antibiotic and metal resistance genes. Special attention must be paid to farm animals, because they produce food such as milk, eggs and meat, with the consequent risk of biological amplification along the food chain. The results of several studies indicate that there is an accumulation of microplastics and nanoplastics in human and animal tissues, with several negative effects, but all the effects in the body have not been ascertained, especially considering the long-term consequences. This review provides an overview of the possible adverse effects of the exposure of livestock to micro- and nanoplastics and assesses the potential risks for the disruption of reproductive physiological functions.

Atrazine sorption on biodegradable microplastics: Significance of microbial aging

The study of the environmental sorption behavior of typical biodegradable microplastics (BMPs) during biodegradation is essential given the different characteristics of BMPs and conventional microplastics (MPs) and the knowledge gap on the sorption capacity of BMPs for pollutants during degradation. In this study, polylactic acid (PLA) and poly (butylene-adipate-co-terephthalate) (PBAT) were chosen as research objects, and the effects of soil microbial aging on their surface properties and atrazine (ATZ) sorption were investigated. The structural composition of the bacterial community was essentially similar between B-PLA and B-PBAT. Microbial aging action created new pores and cavities in PLA, forming microbial films that led to the agglomeration of PLA particles. The microbial aging action destroyed the amorphous regions of PLA and PBAT, resulting in higher crystallinity, and the ester groups broke to form carboxyl groups. The equilibrium sorption (Q_e) of B-PLA increased by 11.12 % compared with PLA, while the Q_e of B-PBAT decreased by 4.95 % compared to PBAT. These results show that soil microbes change the surface properties of PLA and PBAT, thus affecting the sorption mechanism of ATZ, and provide a theoretical premise for the behavior and ecological risk assessment of ATZ in the presence of BMPs.

The effect of polystyrene microplastic and biosolid application on the toxicity and bioaccumulation of cadmium for Enchytraeus crypticus

Plastics smaller than 5 mm that end up in a soil environment are known as microplastics (MPs). Microplastics have become a common contaminant in agricultural areas in addition to metals. However, the effect of cadmium (Cd) on soil organisms has not been clearly defined in the presence of MPs. In addition to MPs, biosolid application as a soil amendment in agricultural lands is also leading to shifts in soil conditions, such as the concentrations of nutrients and organic matter. Therefore, the aim of this study is to investigate the toxicity and bioaccumulation of Cd for Enchytraeus crypticus in the presence of polystyrene (PS)-MPs and biosolids to provide insight into their possible interactions. The lethal toxic concentration (LC50) for Cd was higher than 650 mg Cd/kg dry soil for all conditions. The presence of PS-MPs increased the toxicity of Cd for which EC50 was 102 and 38 mg Cd/kg dry soil without and with Cd, respectively, which may be the result of an increased exposure rate through adsorption of Cd on PS-MPs. On the contrary, the presence of biosolids decreased the toxicity of Cd where EC50 was 193 and 473 mg Cd/kg dry soil for the sets applied with 0.6 and 0.9 g biosolids, respectively. Coexistence of biosolids and PS-MPs decreased the reproduction toxicity of Cd, which is similar to the biosolid effect (EC50 is 305 mg Cd/kg dry soil). Bioaccumulation of Cd only positively correlated with its initial concentration in soil and was not affected by the presence of PS-MPs or biosolids. Integr Environ Assess Manag 2023;19:489-500. © 2022 SETAC.

Responses of individual and combined polystyrene and polymethyl methacrylate nanoplastics on hormonal content, fluorescence/photochemistry of chlorophylls and ROS scavenging capacity in Lemna minor under arsenic-induced oxidative stress

Nanoplastics alter the adverse impacts of hazardous contaminants such as heavy metals by changing their adsorption and accumulation. Few findings are available on the interaction between nanoplastic and heavy metals in plants. However, there is no report on the mechanisms for removing metal stress-mediated oxidative damage by the combination treatments of nanoplastics. To address this lack of information, polystyrene nanoplastic (PS, 100 mg L^-1) and polymethyl methacrylate (PMMA, 100 mg L^-1) were hydroponically applied to Lemna minor exposed to arsenate (As, 100 μM) for 7 days. PS or PMMA caused a reduction in the contents of N, P, K, Ca, Mg and Mn, but the improved contents were detected in the presence of PS or PMMA plus As stress. The hormone contents (auxin, gibberellic acid, cytokinin, salicylic acid and jasmonic acid) reduced by stress were re-arranged through PS or PMMA applications. Based on chlorophyll efficiency, fluorescence kinetics and performance of PSII, the impaired photosynthesis by As stress was improved via PS or PMMA applications. This alleviation did not continue under the combined form of PS and PMMA in As-applied plants. All analyzed antioxidant activity (superoxide dismutase (SOD), catalase (CAT), peroxidase (POX), ascorbate peroxidase (APX), glutathione reductase (GR), glutathione S-transferase (GST), glutathione peroxidase (GPX), monodehydroascorbate reductase (MDHAR) and dehydroascorbate reductase (DHAR)) decreased or unchanged under As, PS or PMMA. Due to the inactivation of the defense system, L. minor had high levels of hydrogen peroxide (H₂O₂) and thiobarbituric acid reactive substances (TBARS), showing lipid peroxidation. After As toxicity, induvial applications of PS or PMMA indicated the activated enzyme capacity (SOD, POX, GST and GPX) and upregulated AsA/DHA, GSH/GSSG and redox state of GSH, which facilitated the removal of radical accumulation. The efficiency of the antioxidant system in As + PS + PMMA-applied L. minor was not enough to remove damage induced by As stress; hereby, TBARS and H₂O₂ contents were similar to the As-treated group. Our findings from alone or combined application of PS and PMMA provide new information to advance the tolerance mechanism against As exposure in L. minor.

Single and composite damage mechanisms of soil polyethylene/polyvinyl chloride microplastics to the photosynthetic performance of soybean (Glycine max [L.] merr.)

INTRODUCTION

Adverse impacts of soil microplastics (MPs, diameter<5 mm) on vegetative growth and crop production have been widely reported, however, the single and composite damage mechanisms of polyethylene (PE) /polyvinyl chloride (PVC) microplastics (MPs) induced photosynthesis inhibition are still rarely known.

METHODS

In this study, two widely distributed MPs, PE and PVC, were added to soils at a dose of 7% (dry soil) to examine the single and composite effects of PE-MPs and PVC-MPs on the photosynthetic performance of soybean.

RESULTS

Results showed PE-MPs, PVC-MPs and the combination of these two contaminants increased malondialdehyde (MDA) content by 21.8-97.9%, while decreased net photosynthesis rate (Pn) by 11.5-22.4% compared to those in non-stressed plants, PVC MPs caused the most severe oxidative stress, while MPs stress resulted in Pn reduction caused by non-stomatal restriction. The reason for this is the single and composite MPs stress resulted in a 6% to 23% reduction in soybean PSII activity RCs reaction centers, along with negative effects on soybean PSII energy uptake, capture, transport, and dissipation. The presence of K-band and L-band also represents an imbalance in the number of electrons on the donor and acceptor side of PSII and a decrease in PSII energy transfer. Similarly, PVC single stress caused greater effects on soybean chloroplast PSII than PE single stress and combined stresses.

DISCUSSION

PE and PVC microplastic stress led to oxidative stress in soybean, which affected the structure and function of photosynthetic PSII in soybean, ultimately leading to a decrease in net photosynthetic rate in soybean.

Nanoplastics in the soil environment: Analytical methods, occurrence, fate and ecological implications

Soils play a very important role in ecosystems sustainability, either natural or agricultural ones, serving as an essential support for living organisms of different kinds. However, in the current context of extremely high plastic pollution, soils are highly threatened. Plastics can change the chemical and physical properties of the soils and may also affect the biota. Of particular importance is the fact that plastics can be fragmented into microplastics and, to a final extent into nanoplastics. Due to their extremely low size and high surface area, nanoplastics may even have a higher impact in soil ecosystems. Their transport through the edaphic environment is regulated by the physicochemical properties of the soil and plastic particles themselves, anthropic activities and biota interactions. Their degradation in soils is associated with a series of mechanical, photo-, thermo-, and bio-mediated transformations eventually conducive to their mineralisation. Their tiny size is precisely the main setback when it comes to sampling soils and subsequent processes for their identification and quantification, albeit pyrolysis coupled with gas chromatography-mass spectrometry and other spectroscopic techniques have proven to be useful for their analysis. Another issue as a consequence of their minuscule size lies in their uptake by plants roots and their ingestion by soil dwelling fauna, producing morphological deformations, damage to organs and physiological malfunctions, as well as the risks associated to their entrance in the food chain, although current conclusions are not always consistent and show the same pattern of effects. Thus, given the omnipresence and seriousness of the plastic menace, this review article pretends to provide a general overview of the most recent data available regarding nanoplastics determination, occurrence, fate and effects in soils, with special emphasis on their ecological implications.

The strategic applications of natural polymer nanocomposites in food packaging and agriculture: Chances, challenges, and consumers' perception

Natural polymer-based nanocomposites have received significant attention in both scientific and industrial research in recent years. They can help to eliminate the consequences of application of petroleum-derived polymeric materials and related environmental concerns. Such nanocomposites consist of natural biopolymers (e.g., chitosan, starch, cellulose, alginate and many more) derived from plants, microbes and animals that are abundantly available in nature, biodegradable and thus eco-friendly, and can be used for developing nanocomposites for agriculture and food industry applications. Biopolymer-based nanocomposites can act as slow-release nanocarriers for delivering agrochemicals (fertilizers/nutrients) or pesticides to crop plants to increase yields. Similarly, biopolymer-based nanofilms or hydrogels may be used as direct product coating to extend product shelf life or improve seed germination or protection from pathogens and pests. Biopolymers have huge potential in food-packaging. However, their packaging properties, such as mechanical strength or gas, water or microbial barriers can be remarkably improved when combined with nanofillers such as nanoparticles. This article provides an overview of the strategic applications of natural polymer nanocomposites in food and agriculture as nanocarriers of active compounds, polymer-based hydrogels, nanocoatings and nanofilms. However, the risk, challenges, chances, and consumers' perceptions of nanotechnology applications in agriculture and food production and packaging have been also discussed.

A review on the effect of micro- and nano-plastics pollution on the emergence of antimicrobial resistance

The recent upsurge in the studies on micro/nano plastics and antimicrobial resistance genes has proven their deleterious effects on the environmental and human health. Till-date, there is a scarcity of studies on the interactions of these two factors and their combined influence. The interaction of microplastics has led to the formation of new plastics namely plastiglomerates, pyroplastics. and anthropoquinas. It has long been ignored that the occurrence of microplastics has become a breeding ground for the emergence of antimicrobial resistance genes. Evidently microplastics are also associated with the occurrence of other pollutants such as polyaromatic hydrocarbons and pesticides. The increased use of antibiotics (after Covid breakout) has further elevated the detrimental effects on human health. Therefore, this study highlights the relation of microplastics with antibiotic resistance generation. The factors such as uncontrolled use of antibiotics and negligent plastic consumption has been evaluated. Furthermore, the future research prospective was provided that can be helpful in correctly identifying the seriousness of the environmental occurrence of these pollutants.

Biodegradable Polyesters and Low Molecular Weight Polyethylene in Soil: Interrelations of Material Properties, Soil Organic Matter Substances, and Microbial Community

Conventional and also biodegradable polymer microplastics have started to be broadly present in the environment, if they end up in soil, they may influence both abiotic and biotic soil properties. In this study, the interactions of polyethylene wax together with three biodegradable polyesters PLA, PHB and PBAT with a soil matrix were investigated over a 1-year incubation period. Soil organic matter content was measured using UV-VIS, the microbial biomass amount was measured using qPCR, the mineralisation of polymers was measured using UGA 3000, the surface of polymers was observed with SEM, live/dead microorganisms were determined by fluorescent microscopy and microbial consortia diversity was analyzed using NGS. The amount of humic substances was generally higher in incubations with slowly degrading polyesters, but the effect was temporary. The microbial biomass grew during the incubations; the addition of PHB enhanced fungal biomass whereas PE wax enhanced bacterial biomass. Fungal microbial consortia diversity was altered in incubations with PHB and PBAT. Interestingly, these two polyesters were also covered in biofilm, probably fungal. No such trend was observed in a metagenomic analysis of bacteria, although, bacterial biofilm was probably formed on the PE520 surface. Different methods confirmed the effect of certain polymers on the soil environment.

Intake of polyamide microplastics affects the behavior and metabolism of Drosophila

In this study, the effects of polyamide (PA) microplastics on Drosophila were studied by analysing their effects on feeding, fecundity, metabolism and spontaneous activity, using Drosophila as a model organism. In the 0.1 g/L and 1 g/L groups, there was an increase in the amount of food consumed by female Drosophila melanogaster and a decrease in the amount of food consumed by males in both the 0.1 g/L and 20 g/L groups. In the TG assay, males showed a significant decrease in the 10 g/L and 20 g/L groups. The male group showed a significant decrease in protein content in the 10 g/L and 20 g/L groups. Glucose content decreased in the female Drosophila 1g/L and 10 g/L groups. The highest concentration group of 20 g/L showed a decrease in glucose content in male Drosophila. Only the male Drosophila in the highest concentration group showed increased daytime activity. Egg production by females decreased significantly after feeding microplastic food. The above assays demonstrate the potential effects of PA microplastics on flies, where the consumption of food containing microplastics leads to oxidative stress and inflammation, thus affecting the nutritional metabolism of flies.

A Method of Managing Waste Oak Flour as a Biocomponent for Obtaining Composites Based on Modified Soybean Oil

The aim of the present research was the development of a management method for wood-processing waste that was obtained during the production of parquet flooring. Currently mostly useless, such waste mainly ends up in landfills. The oak waste flour was used as a reinforcement material for epoxy biocomposites based on the polyaddition product of epoxidized soybean oil and bisphenol-A (ESBO_BPA). The biofiller was subjected to mercerization, acetylation, and diisocyanate modification to increase the typically poor compatibility between the highly hydrophilic wood fibers and the hydrophobic polymer matrix. Among the analyzed epoxy biocomposites, which contained about 60% raw materials of natural origin, it was found that the best mechanical properties were recorded for cured samples of the ESBO_BPA composition filled with 5 wt % of oak flour mercerized using a 5% solution of NaOH. It was also proven that a higher concentration of alkali deteriorated the mechanical-strengthening properties of the wood filler. The acetylation of the biofiller independently in the best elimination of hydroxyl groups from its structure also removed irregular strips and smoothed its surface. This resulted in a poorer wettability of the oak flour surface by the polymer and consequently an easier pullout of the filler from the polymer matrix and worse mechanical properties of the wood/epoxy composite. To the best of the authors' knowledge, the present research was the first to examine the possibility of the application of parquet flooring post-production wood flour in biomaterials based on a polyaddition product of epoxidized soybean oil and bisphenol-A.

Removal of nanoplastics in water treatment processes: A review

Nanoplastics are drawing a significant attention as a result of their propensity to spread across the environment and pose a threat to all organisms. The presence of nanoplastics in water is given attention nowadays as the transit of nanoplastics occurs through the aquatic ecosphere besides terrestrial mobility. The principal removal procedures for macro-and micro-plastic particles are effective, but nanoparticles escape from the treatment, increasing in the water and significantly influencing the society. This critical review is aimed to bestow the removal technologies of nanoplastics from aquatic ecosystems, with a focus on the treatment of freshwater, drinking water, and wastewater, as well as the importance of transit and its impact on health concerns. Still, there exists a gap in providing a collective knowledge on the methods available for nanoplastics removal. Hence, this review offered various nanoplastic removal technologies (microorganism-based degradation, membrane separation with a reactor, and photocatalysis) that could be the practical/effective measures along with the traditional procedures (filtration, coagulation, centrifugation, flocculation, and gravity settling). From the analyses of different treatment systems, the effectiveness of nanoplastics removal depends on various factors, source, size, and type of nanoplastics apart from the treatment method adopted. Combined removal methods, filtration with coagulation offer great scope for the removal of nanoplastics from drinking water with >99 % efficiency. The collected data could serve as base-line information for future research and development in water nanoplastics cleanup.

Toxicity of micro(nano)plastics with different size and surface charge on human nasal epithelial cells and rats via intranasal exposure

Micro (nano)plastics (MNPs) have become emerging environmental contaminants, yet their toxicity and systemic effects via intranasal exposure remain unclear. This study investigated the in vitro toxicity of thirteen polystyrene MNPs with different surface functionalization (carboxylic (C-PS), amino (A-PS), and bare (PS)) and sizes (20-2000 nm) on human nasal epithelial cells (HNEpCs) at 10-1250 μg/mL as well as their in vivo toxicity to rats via intranasal administration at 125 μg/mL. The in vitro study showed that PS20, PS50, A-PS50, PS500, and A-PS500 significantly inhibited cell viability, which was dependent on particle concentration. A-PS induced higher cytotoxicity than C-PS and PS, and most MNPs inhibited cell proliferation after 24-h. Flow cytometry analysis suggested that PS induced cell apoptosis, while A-PS caused cell necrosis. MNPs were phagocytosed by HNEpCs and entered nucleus. The in vivo study showed that MNPs inhibited dietary behaviors of rats. Histological analysis indicated that PS20, PS200, and A-PS50 thinned out nasal mucosa. Immunohistochemical analysis revealed that exposure to PS20, PS200, and A-PS50 enhanced expression of transient receptor potential cation channel subfamily M (melastatin) member 8 (TRPM8). Systemic effects including hepatocyte cytoplasmic vacuolation and renal tubule dilatation were observed. The results suggested that nasal inhalation of MNPs may disturb energy metabolism and damage upper respiratory tract, liver, and kidneys.

The impacts of nanoplastic toxicity on the accumulation, hormonal regulation and tolerance mechanisms in a potential hyperaccumulator - Lemna minor L

Plastic pollution, which is currently one of the most striking problems of our time, raises concerns about the dispersal of micro and nano-sized plastic particles in ecosystems and their toxic effects on living organisms. This study was designed to reveal the toxic effects of polystyrene nanoplastic (PS NP) exposure on the freshwater macrophyte Lemna minor. In addition, elucidating the interaction of this aquatic plant, which is used extensively in the phytoremediation of water contaminants and wastewater treatment facilities, with nanoplastics will guide the development of remediation techniques. For this purpose, we examined nanoplastic accumulation, oxidative stress markers, photosynthetic efficiency, antioxidant system activity and phytohormonal changes in L. minor leaves subjected to PS NP stress (P-1, 100 mg L^-1; P-2, 200 mg L^-1 PS NP). Our results showed no evidence of PS NP-induced oxidative damage in P-1 group plants, although PS NP accumulation reached 56 µg g^-1 in the leaves. Also, no significant changes in chlorophyll a fluorescence parameters were observed in this group, indicating unaffected photosynthetic efficiency. PS NP exposure triggered the antioxidant system in L. minor plants and resulted in a 3- and 4.6-fold increase in superoxide dismutase (SOD) activity in the P-1 and P-2 groups. On the other hand, high-dose PS NP treatment resulted in insufficient antioxidant activity in the P-2 group and increased hydrogen peroxide (H₂O₂) and lipid peroxidation (TBARS contents) by 25 % and 17 % compared to the control plants. Furthermore, PS NP exposure triggered abscisic acid biosynthesis (two-fold in the P-1 and three-fold in the P-2 group), which is also involved in regulating the stress response. In conclusion, L. minor plants tolerated NP accumulation without growth suppression, oxidative stress damage and limitations in photosynthetic capacity and have the potential to be used in remediation studies of NP-contaminated waters.