Ecotoxicity and genotoxicity of polystyrene microplastics on higher plant Vicia faba

Microplastics in the soil-water-food nexus: Inclusive insight into global research findings

Nuisance imposed by biotic and abiotic stressors on diverse agroecosystems remains an area of focus for the scientific fraternity. However, emerging contaminants such as microplastics (MP) have imposed additional dimension (alone or in combinations with other stressors) in agroecosystems and keep escalating the challenges to achieve sustainability. MP are recognized as persistent anthropogenic contaminants, fetch global attention due to their unique chemical features that keeps themselves unresponsive to the decaying process. This review has been theorized to assess the current research trends (along with possible gap areas), widespread use of MP, enhancement of the harshness of heavy metals (HMs), complex interactions with physico-chemical constituents of arable soil, accumulation in the edible parts of field crops, dairy products, and other sources to penetrate the food web. So far, the available review articles are oriented to a certain aspect of MP and lack a totality when considered from in soil-water-food perspective. In short, a comprehensive perspective of the adverse effects of MP on human health has been assessed. Moreover, an agro-techno-socio-health prospective-oriented critical assessment of policies and remedial measures linked with MP has provided an extra edge over other similar articles in influential future courses of research.

Microplastics in soil affect the growth and physiological characteristics of Chinese fir and Phoebe bournei seedlings

Pot experiments were conducted using Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.) and Phoebe bournei (Hemsl.) Yang) to investigate whether soil microplastics adversely affect the nurturing and renewal of plantations. Microplastics composed of polyethylene and polypropylene with a size of 48 μm were used. The treatments included a control group (without microplastics) and groups treated with microplastic concentrations of 1% and 2% (w/w). The effects of microplastics on the growth, photosynthetic pigments in leaves, antioxidant systems, and osmotic regulation substances of the seedlings were analysed by measuring the seedling height, ground-line diameter growth, chlorophyll (chlorophyll a, chlorophyll b, and total chlorophyll) contents, antioxidant enzyme (superoxide dismutase, peroxidase, catalase) activities, and malondialdehyde, soluble sugar, and soluble protein levels. The results indicated that treatment with 1% polyethylene microplastics increased the chlorophyll a, total chlorophyll, and soluble protein contents in the leaves of both types of seedlings while inhibiting superoxide dismutase and peroxidase activities in P. bournei seedlings. Treatment with 2% polyethylene or polypropylene microplastics suppressed the chlorophyll a, chlorophyll b, and total chlorophyll contents; superoxide dismutase, peroxidase, and catalase activities; and soluble sugar and soluble protein levels in the leaves of both types of seedlings, resulting in reduced growth in terms of height and ground-line diameter. The physiological effects of polyethylene microplastics were more evident than those of polypropylene at the same concentration. The results demonstrated that microplastics can affect photosynthesis, the antioxidant system, and osmotic regulation in Chinese fir and P. bournei seedlings, thereby inhibiting their normal growth and development. Exposure to 1% (w/w) microplastics triggered stress responses in seedlings, whereas 2% (w/w) microplastics impeded seedling growth.

Polystyrene microplastics enhanced the toxicity of cadmium to rice seedlings: Evidence from rice growth, physiology, and element metabolism

Microplastics (MPs) and cadmium (Cd) are toxic to rice; however, the effects and mechanisms of their combined exposure are unclear. The combined exposure effects of polystyrene microplastics (PS-MPs) with different particle sizes (1-10 μm, 50-150 μm) and concentrations (50, 500 mg·L-1) and Cd on rice were explored. PS-MPs combined with Cd amplifies the inhibition of each individual exposure on the height and biomass of rice seedlings, and they showed antagonistic effects. PS-MPs reduced the content of chlorophyll and increased the content of carotenoid rice seedlings significantly. High concentrations of PS-MPs enhanced the inhibition of Cd on chlorophyll content. Cd, PS-MPs single and combined exposures significantly altered the antioxidant enzyme (POD, CAT, SOD) activities in rice seedlings. Under PS-MPs exposure, overall, the MDA content in shoots and roots exhibited opposite trends, with a decrease in the former and an increase in the latter. In comparison with Cd treatment, the combined exposures' shoot and root MDA content was reduced. Cd and PS-MPs showed "low concentration antagonism, high concentration synergism" on the composite physiological indexes of rice seedlings. PS-MPs significantly increased the Cd accumulation in shoots. PS-MPs promoted the root absorption of Cd at 50 mg·L-1 while inhibited at 500 mg·L-1. Cd and PS-MPs treatments interfered with the balance of microelements (Mn, Zn, Fe, Cu, B, Mo) and macroelements (S, P, K, Mg, Ca) in rice seedlings; Mn was significantly inhibited. PS-MPs can enhance of Cd's toxicity to rice seedlings. The combined toxic effects of the two contaminants appear to be antagonistic or synergistic, relying on the particle size and concentration of the PS-MPs. Our findings offer information to help people understanding the combined toxicity of Cd and MPs on crops.

Differences in the uptake and translocation of differentially charged microplastics by the taproot and lateral root of mangroves

The interception of microplastics (MPs) by mangrove roots plays an indispensable role in reducing the environmental risks of MPs. However, there remains limited research on the fate of the intercepted MPs. Hereby, the uptake and subsequent translocation of 0.2 μm and 2 μm PS MPs with different coating charge by the typical salt-secreting mangrove plants (Aegiceras corniculatum) were investigated. Compared to amino-functionalized PS with positive charge (PS-NH2), the visualized results indicated that the efficient uptake of carboxy-functionalized PS with negative charge (PS-COOH) was more dependent on taproots. But for the lateral roots, it only allowed the entry of PS-NH2 instead of PS-COOH. The specific uptake pathways of PS-NH2 on the lateral roots could attribute to the release of H+ and organic acids by root hairs, as well as the relative higher Zeta potential. After entering the Aegiceras corniculatum roots, the translocation of PS MPs was restricted by their particle sizes. Furthermore, the release of PS MPs from Aegiceras corniculatum leaf surfaces through the salt glands and stomata was observed. And the decline in the photochemical efficiency of leaves under PS MPs exposure also indirectly proved the foliar emission of PS MPs. Our study improved the understanding of the environmental behaviors and risks of the retained MPs in mangroves.

Evaluating the role of soil EPS in modifying the toxicity potential of the mixture of polystyrene nanoplastics and xenoestrogen, Bisphenol A (BPA) in Allium cepa L

The coexistence of emerging pollutants like nanoplastics and xenoestrogen chemicals such as Bisphenol A (BPA) raises significant environmental concerns. While the individual impacts of BPA and polystyrene nanoplastics (PSNPs) on plants have been studied, their combined effects are not well understood. This study examines the interactions between eco-corona formation, physicochemical properties, and cyto-genotoxic effects of PSNPs and BPA on onion (Allium cepa) root tip cells. Eco-corona formation was induced by exposing BPA-PSNP mixtures to soil extracellular polymeric substances (EPS), and changes were analyzed using 3D-EEM, TEM, FTIR, hydrodynamic diameter, and contact angle measurements. Onion roots were treated with BPA (2.5, 5, and 10 mgL-1) combined with plain, aminated, and carboxylated PSNPs (100 mgL-1), with and without EPS interaction. Toxicity was assessed via cell viability, oxidative stress markers (superoxide radical, total ROS, hydroxyl radical), lipid peroxidation, SOD and catalase activity, mitotic index, and chromosomal abnormalities. BPA alone increased cytotoxic and genotoxic parameters in a dose-dependent manner. BPA with aminated PSNPs exhibited the highest toxicity among the pristine mixtures, revealing increased chromosomal abnormalities, oxidative stress, and cell mortality with rising BPA concentrations. In-silico experiments demonstrated the relationship between superoxide dismutase (SOD), catalase enzymes, PSNPs, BPA, and their mixtures. EPS adsorption notably reduced cyto-genotoxic effects, lipid peroxidation, and ROS levels, mitigating the toxicity of BPA-PSNP mixtures.

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.

Unveiling the impacts of microplastics on cadmium transfer in the soil-plant-human system: A review

The co-contamination of soils by microplastics (MPs) and cadmium (Cd), one of the most perilous heavy metals, is emerging as a significant global concern, posing risks to plant productivity and human health. However, there remains a gap in the literature concerning comprehensive evaluations of the combined effects of MPs and Cd on soil-plant-human systems. This review examines the interactions and co-impacts of MPs and Cd in soil-plant-human systems, elucidating their mechanisms and synergistic effects on plant development and health risks. We also review the origins and contamination levels of MPs and Cd, revealing that sewage, atmospheric deposition, and biosolid applications are contributors to the contamination of soil with MPs and Cd. Our meta-analysis demonstrates that MPs significantly (p<0.05) increase the bioavailability of soil Cd and the accumulation of Cd in plant shoots by 6.9 and 9.3 %, respectively. The MPs facilitate Cd desorption from soils through direct adsorption via surface complexation and physical adsorption, as well as indirectly by modifying soil physicochemical properties, such as pH and dissolved organic carbon, and altering soil microbial diversity. These interactions augment the bioavailability of Cd, along with MPs, adversely affect plant growth and its physiological functions. Moreover, the ingestion of MPs and Cd through the food chain significantly enhances the bioaccessibility of Cd and exacerbates histopathological alterations in human tissues, thereby amplifying the associated health risks. This review provides insights into the coexistence of MPs and Cd and their synergistic effects on soil-plant-human systems, emphasizing the need for further research in this critical subject area.

Meta-analysis reveals the combined effects of microplastics and heavy metal on plants

The combined pollution of microplastics and heavy metals is becoming increasingly serious, and its effects on toxicology and heavy metal accumulation of plants are closely related to crop yield and population health. Here, we collected 57 studies to investigate the effect of microplastics on heavy metal accumulation in plants and their combined toxicity. An assessment was conducted to discover the primary pollutant responsible for the toxicity of combined pollution on plants. The study examined the influence of microplastic characteristics, heavy metal characteristics, and experimental methods on this pollutant. The results showed that combined toxicity of plants was more similar to heavy metals, whereas microplastics interacted with heavy metals mainly by inducing oxidative stress damage. Culture environment, heavy metal type, experimental duration, microplastic concentration and microplastic size were the main factors affecting heavy metal accumulation in plants. There was a negative correlation between experimental duration, microplastic concentration and microplastic size with heavy metal accumulation in plants. The interactions among influencing factors were found, and microplastic biodegradation was the core factor of the strong interaction. These results provided comprehensive insights and guiding strategies for environmental and public health risks caused by the combined pollution of microplastics and heavy metals.

The Effects of Polypropylene Microplastics on the Removal of Nitrogen and Phosphorus from Water by Acorus calamus, Iris tectorum and Functional Microorganisms

Polypropylene microplastics (PP-MPs), an emerging pollutant, adversely affect the ability of aquatic plants to restore water bodies, thereby compromising the functionality and integrity of wetland ecosystems. This study examines the effects of microplastic stress on the nitrogen and phosphorus removal capacities of Acorus calamus and Iris tectorum, as well as on functional microorganisms within the aquatic system. The findings indicate that under PP-MP stress, the nitrogen and phosphorus absorption capabilities of both plants were diminished. Additionally, there was a significant reduction in the metabolic enzyme activities related to nitrogen and phosphorus in the plants, alongside a notable decrease in leaf nitrogen content. PP-MPs hinder the nutrient uptake of plants, affecting their growth and indirectly reducing their ability to utilize nitrogen and phosphorus. Specifically, in the 10 mg·L-1 treatment group, A. calamus and I. tectorum showed reductions in leaf nitrogen content by 23.1% and 31.0%, respectively, and by 14.8% and 27.7% in the 200 mg·L-1 treatment group. Furthermore, I. tectorum had higher leaf nitrogen levels than A. calamus. Using fluorescent tagging, the distribution of PP-MPs was traced in the roots, stems, and leaves of the plants, revealing significant growth impairment in both species. This included a considerable decline in photosynthetic pigment synthesis, enhanced oxidative stress responses, and increased lipid peroxidation in cell membranes. PP-MP exposure also significantly reduced the abundance of functional microorganisms involved in denitrification and phosphorus removal at the genus level in aquatic systems. Ecological function predictions revealed a notable decrease in nitrogen cycling functions such as nitrogen respiration and nitrite denitrification among water microorganisms in both treatment groups, with a higher ecological risk potential in the A. calamus treatment group. This study provides new insights into the potential stress mechanisms of PP-MPs on aquatic plants involved in water body remediation and their impacts on wetland ecosystems.

Environmental concentrations of 6PPD and 6PPD-Q cause oxidative damage and alter metabolism in Eichhornia crassipes

N-(1,3-dimethylbutyl)-N '-phenyl-p-phenylenediamine (6PPD) and N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine-quinone (6PPD-Q) are ubiquitous in the environment and can cause toxicity to aquatic animals. However, research on the toxicological effects of 6PPD and 6PPD-Q on aquatic plants remains limited. The present study investigated the physiological, biochemical, and metabolic responses of the floating aquatic plant Eichhornia crassipes (E. crassipes) to environmentally relevant concentrations (0.1, 1, and 10 μg·L-1) of 6PPD and 6PPD-Q. We found that 6PPD and 6PPD-Q elicited minimal effects on plant growth, but 6PPD induced a concentration-dependent decrease in the content of photosynthetic pigments. Low doses (0.1 μg·L-1 and 1 μg·L-1) of 6PPD-Q significantly elevated Reactive Oxygen Species (ROS) content in E. crassipes roots, indicating oxidative damage. Furthermore, 6PPD-Q induced a more pronounced osmotic stress compared to 6PPD. Metabolic analyses revealed that carbohydrates were significantly altered under 6PPD and 6PPD-Q treatments. The findings of this study enhance the understanding of the environmental risks posed by 6PPD and 6PPD-Q to plants and reveal the potential mechanisms of phytotoxicity.

Visual observation of polystyrene nano-plastics in grape seedlings of Thompson Seedless and assessing their effects via transcriptomics and metabolomics

Micro/nano-plastics (MNPs) are emerging non-point source pollutants that have garnered increasing attention owing to their threat to ecosystems. Studies on the effects of MNPs on horticultural crops are scarce. Specifically, whether MNPs can be absorbed and transported by grapevines have not been reported. To fill this gap, we added polystyrene nanoplastics (PS-NPs, 100 nm) to a hydroponic environment and observed their distribution in grape seedlings of Thompson Seedless (TS, Vitis vinifera L.). After 15 d of exposure, plastic nanospheres were detected on the cell walls of the roots, stems, and leaves using confocal microscopy and scanning electron microscopy. This indicated that PS-NPs can also be absorbed by the root system through the epidermis-cortex interface in grapevines and transported upward along the xylem conduit. Furthermore, we analyzed the molecular response mechanisms of TS grapes to the PS-NPs. Through the measurement of relevant indicators and combined omics analysis, we found that plant hormone signal transduction, flavonoid and flavonol biosynthesis, phenylpropanoid biosynthesis, and MAPK signaling pathway biosynthesis played crucial roles in its response to PS-NPs. The results not only revealed the potential risk of MNPs being absorbed by grapevines and eventually entering the food chain but also provided valuable scientific evidence and data for the assessment of plant health and ecological risk.

Unveiling the impacts of microplastic pollution on soil health: A comprehensive review

Soil contamination by microplastics (MPs) has emerged as a significant global concern. Although traditionally associated with crop production, contemporary understanding of soil health has expanded to include a broader range of factors, including animal safety, microbial diversity, ecological functions, and human health protection. This paradigm shifts underscores the imperative need for a comprehensive assessment of the effects of MPs on soil health. Through an investigation of various soil health indicators, this review endeavors to fill existing knowledge gaps, drawing insights from recent studies conducted between 2021 and 2024, to elucidate how MPs may disrupt soil ecosystems and compromise their crucial functions. This review provides a thorough analysis of the processes leading to MP contamination in soil environments and highlights film residues as major contributors to agricultural soils. MPs entering the soil detrimentally affect crop productivity by hindering growth and other physiological processes. Moreover, MPs hinder the survival, growth, and reproductive rates of the soil fauna, posing potential health risks. Additionally, a systematic evaluation of the impact of MPs on soil microbes and nutrient cycling highlights the diverse repercussions of MP contamination. Moreover, within soil-plant systems, MPs interact with other pollutants, resulting in combined pollution. For example, MPs contain oxygen-containing functional groups on their surfaces that form high-affinity hydrogen bonds with other pollutants, leading to prolonged persistence in the soil environment thereby increasing the risk to soil health. In conclusion, we succinctly summarize the current research challenges related to the mediating effects of MPs on soil health and suggest promising directions for future studies. Addressing these challenges and adopting interdisciplinary approaches will advance our understanding of the intricate interplay between MPs and soil ecosystems, thereby providing evidence-based strategies for mitigating their adverse effects.

Polyvinyl chloride and polybutylene adipate microplastics affect peanut and rhizobium symbiosis by interfering with multiple metabolic pathways

Microplastics (MPs), widely presented in cultivated soil, have caused serious stresses on crop growth. However, the mechanism by which MPs affect legumes and rhizobia symbiosis is still unclear. Here, peanut seedlings were inoculated with Bradyrhizobium zhanjiangense CCBAU 51778 and were grown in vermiculite with 3 %/5 % (w/w) addition of PVC (polyvinyl chloride)-MPs/PBAT (polybutylene adipate)-MPs. PVC-MPs and PBAT-MPs separately decreased nodule number by 33-100 % and 2.62-80.91 %. Transcriptome analysis showed that PVC-MPs affected more DEGs (differentially expressed genes) than PBAT-MPs, indicating PVC-MPs were more devastating for the symbiosis than PBAT-MPs. Functional annotation revealed that PVC-MPs and PBAT-MPs enriched DEGs related to biosynthesis pathways such as flavonoid, isoflavonoid, and phenylpropanoid, in peanut. And when the dose increased from 3 % to 5 %, PVC-MPs mainly enriched the pathways of starch and sucrose metabolism, alanine, aspartate and glutamate metabolism, diterpenoid biosynthesis, etc.; PBAT-MPs enriched cysteine and methionine metabolism, photosynthesis, MAPK signaling, and other pathways. These significantly enriched pathways functioned in reducing nodule number and promoting peanut tolerance to MPs stresses. This study reveals the effect of PVC-MPs and PBAT-MPs on peanut and rhizobium symbiosis, and provides new perspectives for legume production and environmental safety.

Microplastic-contamination can reshape plant community by affecting soil properties

Microplastics, as emerging contaminants, pose a serious threat to terrestrial ecosystems, yet their impact on plant communities remains largely unexplored. This study utilized the soil seed bank to establish naturally germinated plant communities and investigated the effects of polyethylene (PE) and polypropylene (PP) on community characteristics. Additionally, the study aimed to elucidate the mechanisms by which variations in soil properties influenced plant community. The results indicated that microplastics led to a significant increase in soil available potassium (AK), likely due to alterations in soil microorganism proliferation. Furthermore, microplastics caused a decrease in soil salinity, total phosphorus (TP), and ammonium nitrogen (AN). Additionally, plant community composition shifted, resulting in reduced stability and niche breadth of dominant species. Microplastics also impacted niche overlap and interspecific associations among dominant species, possibly due to the reduced accessibility of resources for dominant species. Salinity, AK, and TP were identified as major drivers of changes in niche breadth, niche overlap, and community stability, with TP exerting the strongest impact on plant community composition. These findings provide valuable insights for the restoration of plant communities in coastal saline-alkali wetland contaminated by microplastics.

Effects of polystyrene microplastic composite with florfenicol on photosynthetic carbon assimilation of rice (Oryza sativa L.) seedlings: Light reactions, carbon reactions, and molecular metabolism

The effects of co-exposure to antibiotics and microplastics in agricultural systems are still unclear. This study investigated the effects of florfenicol (FF) and polystyrene microplastics (PS-MPs) on photosynthetic carbon assimilation in rice seedlings. Both FF and PS-MPs inhibited photosynthesis, while PS-MPs can alleviate the toxicity of FF. Chlorophyll synthesis genes (HEMA, HEMG, CHLD, CHLG, CHLM, and CAO) were down-regulated, whereas electron transport chain genes (PGR5, PGRL1A, PGRL1B, petH, and ndhH) were up-regulated. FF inhibited linear electron transfer (LET) and activated cyclic electron transfer (CET), which was consistent with the results of the chlorophyll fluorescence parameters. The photosynthetic carbon assimilation pathway was altered, the C3 pathway enzyme Ribulose1,5-bisphosphatecarboxylase/oxygenase (RuBisCO) was affected, C4 enzyme ((phosphoenolpyruvate carboxykinase (PEPCK), pyruvate orthophosphate dikinase (PPDK), malate dehydrogenase (MDH), and phosphoenolpyruvate carboxylase (PEPC))) and related genes were significantly up-regulated, suggesting that the C3 pathway is converted to C4 pathway for self-protection. The key enzymes involved in photorespiration, glycolate oxidase (GO) and catalase (CAT), responded positively, photosynthetic phosphorylation was inhibited, and ATP content and H+-ATPase activity were suppressed, nutrient content (K, P, N, Ca, Mg, Fe, Cu, Zn, Mn, and Ni) significantly affected. Transcriptomic analysis showed that FF and PS-MPs severely affected the photosynthetic capacity of rice seedlings, including photosystem I, photosystem II, non-photochemical quenching coefficients, and photosynthetic electron transport.

Multiomics analysis reveals a substantial decrease in nanoplastics uptake and associated impacts by nano zinc oxide in fragrant rice (Oryza sativa L.)

Nanoplastics (NPs) have emerged as global environmental pollutants with concerning implications for sustainable agriculture. Understanding the underlying mechanisms of NPs toxicity and devising strategies to mitigate their impact is crucial for crop growth and development. Here, we investigated the nanoparticles of zinc oxide (nZnO) to mitigate the adverse effects of 80 nm NPs on fragrant rice. Our results showed that optimized nZnO (25 mg L-1) concentration rescued root length and structural deficits by improving oxidative stress response, antioxidant defense mechanism and balanced nutrient levels, compared to seedlings subjected only to NPs stress (50 mg L-1). Consequently, microscopy observations, Zeta potential and Fourier transform infrared (FTIR) results revealed that NPs were mainly accumulated on the initiation joints of secondary roots and between cortical cells that blocks the nutrients uptake, while the supplementation of nZnO led to the formation of aggregates with NPs, which effectively impedes the uptake of NPs by the roots of fragrant rice. Transcriptomic analysis identified a total of 3973, 3513 and 3380 differentially expressed genes (DEGs) in response to NPs, nZnO and NPs+nZnO, respectively, compared to the control. Moreover, DEGs were significantly enriched in multiple pathways including biosynthesis of secondary metabolite, phenylpropanoid biosynthesis, amino sugar and nucleotide sugar metabolism, carotenoid biosynthesis, plant-pathogen interactions, MAPK signaling pathway, starch and sucrose metabolism, and plant hormone signal transduction. These pathways could play a significant role in alleviating NPs toxicity and restoring fragrant rice roots. Furthermore, metabolomic analysis demonstrated that nZnO application restored 2-acetyl-1-pyrroline (2-AP) pathways genes expression, enzymatic activities, and the content of essential precursors related to 2-AP biosynthesis under NPs toxicity, which ultimately led to the restoration of 2-AP content in the leaves. In conclusion, this study shows that optimized nZnO application effectively alleviates NPs toxic effects and restores both root structure and aroma production in fragrant rice leaves. This research offers a sustainable and practical strategy to enhance crop production under NPs toxicity while emphasizing the pivotal role of essential micronutrient nanomaterials in agriculture.

Impact of microplastic residues from polyurethane films on crop growth: Unraveling insights through transcriptomics and metabolomics analysis

The utilisation of coated controlled-release fertilizers (CRFs) leads to the persistence of residual plastic films in agricultural soils, posing a potential threat to crop health. This study investigates the impacts of four residual films (0.39 %, w/w) derived from CRFs in soil, including petrochemical polyether, bio-based polyether, castor oil polyester, and wheat straw polyester polyurethane on wheat growth. This study found that PecPEUR significantly reduced wheat plant height, stem diameter, leaf area, and aboveground fresh weight by 24.8 %, 20.2 %, and 25.7 %. Through an in-depth exploration of transcriptomics and metabolomics, it has been discovered that all residual films disrupted glycolysis-related metabolic pathways in wheat roots, affecting seedling growth. Among them, PecPEUR significantly reduced the fresh weight of aboveground parts by 20.5 %. In contrast, polyester polyurethane residue had no discernible impact on aboveground wheat growth. This was attributed to the enrichment of wheat root genes in jasmonic acid and γ-aminobutyric acid metabolic pathways, thus mitigating oxidative stress, enhancing stress resistance, and ensuring normal plant growth. This study, for the first time, provides comprehensive insights into the effects of polyurethane film residue on wheat seedling growth, underscoring its potential as a promising alternative to conventional plastics in soil.

Analysis of the Adsorption Behavior of Phenanthrene on Microplastics Based on Two-Dimensional Correlation Spectroscopy

Microplastics (MPs), an emerging pollutant, widely co-occur with polycyclic aromatic hydrocarbons (PAHs) in the environment. Therefore, the interaction between MPs and PAHs has been the focus of much attention in recent years. In this study, three types of MPs, i.e., polypropylene, polystyrene, and poly(vinyl chloride), with the same main chain were selected as the adsorbents, with phenanthrene (PHE) as the representative PAHs. The adsorption mechanisms were explored from the perspective of the molecular spectral level using a combination of Fourier transform infrared spectroscopy (FT-IR) with a two-dimensional correlation technique. The adsorption kinetics results showed that the adsorption of PHE on the three MPs was dominated by chemisorption. However, the FT-IR analysis results indicated that no new covalent bond was created during the adsorption process. Based on the above research, a generalized two-dimensional (2D) correlation spectral technique was employed to investigate the sequence of functional group changes during the adsorption process for different MPs. Furthermore, the hybrid 2D correlation spectral technique explored the effect of side groups attached to the main chain molecules of MPs on adsorption. The results showed that for all three MPs, the functional groups in the side chain have a higher affinity for PHE, which is due to their higher hydrophobicity. This study provides a feasible way to analyze the adsorption of pollutants on MPs, and the results are important for understanding the adsorption interaction between PAHs and MPs in the aquatic environment.

Effect of cadmium and polystyrene nanoplastics on the growth, antioxidant content, ionome, and metabolism of dandelion seedlings

Cadmium is the most prevalent heavy metal pollutant in the environment and can be readily combined with micro/nanoplastics (M/NPs) to change their bioavailability. In the present study, we comprehensively investigated the effect of polystyrene (PS) NPs on dandelion plants grown under Cd stress. Cd exposure significantly inhibited the growth of dandelion seedlings, resulting in a decrease in seedling elongation from 26.47% to 28.83%, a reduction in biomass from 29.76% to 54.14%, and an exacerbation of lipid peroxidation and oxidative stress. The interaction between PS NPs and Cd resulted in the formation of larger aggregates, with the Cd bioavailability reduced by 12.56%. PS NPs affect ion absorption by regulating reactive oxygen production and increasing superoxide dismutase activity, thereby mitigating the adverse effects of Cd. PSCd aggregates induced significant changes in the metabolic profiles of dandelions, affecting various carbohydrates related to alcohols, organic acids, sugar metabolism, and bioactive components related to flavonoids and phenolic acids. Furthermore, based on a structural equation model, exposure to PSCd activated oxidative stress and nutrient absorption, thereby affecting plant growth and Cd accumulation. Overall, our study provides valuable insights into the effects of PS NPs on Cd bioavailability, accumulation, and plant growth, which are crucial for understanding the food safety of medicinal plants in a coexistence environment.

Micro and nanoplastics pollution: Sources, distribution, uptake in plants, toxicological effects, and innovative remediation strategies for environmental sustainability

Microplastics and nanoplastics (MNPs), are minute particles resulting from plastic fragmentation, have raised concerns due to their widespread presence in the environment. This study investigates sources and distribution of MNPs and their impact on plants, elucidating the intricate mechanisms of toxicity. Through a comprehensive analysis, it reveals that these tiny plastic particles infiltrate plant tissues, disrupting vital physiological processes. Micro and nanoplastics impair root development, hinder water and nutrient uptake, photosynthesis, and induce oxidative stress and cyto-genotoxicity leading to stunted growth and diminished crop yields. Moreover, they interfere with plant-microbe interactions essential for nutrient cycling and soil health. The research also explores the translocation of these particles within plants, raising concerns about their potential entry into the food chain and subsequent human health risks. The study underscores the urgency of understanding MNPs toxicity on plants, emphasizing the need for innovative remediation strategies such as bioremediation by algae, fungi, bacteria, and plants and eco-friendly plastic alternatives. Addressing this issue is pivotal not only for environmental conservation but also for ensuring sustainable agriculture and global food security in the face of escalating plastic pollution.

Microplastics in agroecosystems: Soil-plant dynamics and effective remediation approaches

Increasing microplastic (MP) pollution, primarily from anthropogenic sources such as plastic film mulching, waste degradation, and agricultural practices, has emerged as a pressing global environmental concern. This review examines the direct and indirect effects of MPs on crops, both in isolation and in conjunction with other contaminants, to elucidate their combined toxicological impacts. Organic fertilizers predominantly contain 78.6% blue, 9.5% black, and 8.3% red MPs, while irrigation water in agroecosystems contains 66.2% white, 15.4% blue, and 8.1% black MPs, ranging from 0-1 mm to 4-5 mm in size. We elucidate five pivotal insights: Firstly, soil MPs exhibit affinity towards crop roots, seeds, and vascular systems, impeding water and nutrient uptake. Secondly, MPs induce oxidative stress in crops, disrupting vital metabolic processes. Thirdly, leachates from MPs elicit cytotoxic and genotoxic responses in crops. Fourthly, MPs disrupt soil biotic and abiotic dynamics, influencing water and nutrient availability for crops. Lastly, the cumulative effects of MPs and co-existing contaminants in agricultural soils detrimentally affect crop yield. Thus, we advocate agronomic interventions as practical remedies. These include biochar input, application of growth regulators, substitution of plastic mulch with crop residues, promotion of biological degradation, and encouragement of crop diversification. However, the efficacy of these measures varies based on MP type and dosage. As MP volumes increase, exploring alternative mitigation strategies such as bio-based plastics and environmentally friendly biotechnological solutions is imperative. Recognizing the persistence of plastics, policymakers should enact legislation favoring the mitigation and substitution of non-degradable materials with bio-derived or compostable alternatives. This review demonstrates the urgent need for collective efforts to alleviate MP pollution and emphasizes sustainable interventions for agricultural ecosystems.

The native submerged plant, Hydrilla verticillata outperforms its exotic confamilial with exposure to polyamide microplastic pollution: Implication for wetland revegetation and potential driving mechanism

Microplastic pollution and biological invasion, as two by-products of human civilization, interfere the ecological function of aquatic ecosystem. The restoration of aquatic vegetation has been considered a practical approach to offset the deterioration of aquatic ecosystem. However, a lack of knowledge still lies in the species selection in the revegetation when confronting the interference from microplastic pollution and exotic counterpart. The present study subjected the native submerged species, Hydrilla verticillata and its exotic confamilial, Elodea nuttallii to the current and future scenarios of polyamide microplastic pollution. The plant performance proxies including biomass and ramet number were measured. We found that the native H. verticillata maintained its performance while the exotic E. nuttallii showed decreases in biomass and ramet number under severest pollution conditions. The restoration of native submerged plant such as H. verticillata appeared to be more effective in stabilizing aquatic vegetation in the scenario of accelerating microplastic pollution. In order to explore the underlying driving mechanism of performance differentiation, stress tolerance indicators for plants, sediment enzymatic activity and sediment fungal microbiome were investigated. We found that polyamide microplastic had weak effects on stress tolerance indicators for plants, sediment enzymatic activity and sediment fungal diversity, reflecting the decoupling between these indicators and plant performance. However, the relative abundance of sediment arbuscular mycorrhizal fungi for H. verticillata significantly increased while E. nuttallii gathered "useless" ectomycorrhizal fungi at the presence of severest polyamide microplastic pollution. We speculate that the arbuscular mycorrhizal fungi assisted the stabilization of plant performance for H. verticillata with exposure to the severest polyamide microplastic pollution.

Microplastic accumulation and oxidative stress in sweet pepper (Capsicum annuum Linn.): Role of the size effect

Microplastics (MPs), which are widely dispersed in terrestrial environments, threaten crop growth and human food security. However, plant accumulation and phytotoxicity related to the size effects of MPs remain insufficiently explored. This study investigated the accumulation and toxicity of two sizes of MPs on Capsicum annuum Linn. (C. annuum) through fluorescence tracing and antioxidant defense system assessment. The results revealed that the size of MPs significantly impacts their accumulation characteristics in C. annuum roots, leading to variations in toxic mechanisms, including oxidative stress and damage. Smaller MPs and higher exposure concentrations result in more pronounced growth inhibition. C. annuum roots have a critical size threshold for the absorption of MPs of approximately 1.2 μm. MPs that enter the root tissue exhibit an aggregated form, with smaller-sized MPs displaying a greater degree of aggregation. MP exposure induces oxidative stress in root tissues, with high concentrations of smaller MPs causing lipid peroxidation. Analysis of the IBR values revealed that C. annuum roots utilize ascorbic acid (ASA) to prevent oxidative damage caused by larger MPs. Conversely, smaller MPs primarily induce superoxide dismutase (SOD) and glutathione (GSH). These results emphasize the significant impact of MP size on plant antioxidant defense response mechanisms, laying the foundation for further investigating the implications for human health.

Microplastic exposure inhibits nitrate uptake and assimilation in wheat plants

Microplastic (MP) contamination in soil severely impairs plant growth. However, mechanisms underlying the effects of MPs on plant nutrient uptake remain largely unknown. In this study, we revealed that NO3- content was significantly decreased in shoots and roots of wheat plants exposed to high concentrations (50-100 mg L-1) of MPs (1 μm and 0.1 μm; type: polystyrene) in the hydroponic solution. Isotope labeling experiments demonstrated that MP exposure led to a significant inhibition of NO3- uptake in wheat roots. Further analysis indicated that the presence of MPs markedly inhibited root growth and caused oxidative damage to the roots. Additionally, superoxide dismutase and peroxidase activities in wheat roots decreased under all MP treatments, whereas catalase and ascorbate peroxidase activities significantly increased under the 100 mg L-1 MP treatment. The transcription levels of most nitrate transporters (NRTs) in roots were significantly downregulated by MP exposure. Furthermore, exposure to MPs distinctly suppressed the activity of nitrate reductase (NR) and nitrite reductase (NiR), as well as the expression levels of their coding genes in wheat shoots. These findings indicate that a decline in root uptake area and root vitality, as well as in the expression of NRTs, NR, and NiR genes caused by MP exposure may have adverse effects on NO3- uptake and assimilation, consequently impairing normal growth of plants.

Dose-dependent effects of polystyrene nanoplastics on growth, photosynthesis, and astaxanthin synthesis in Haematococcus pluvialis

Microalgae play an important role in aquatic ecosystems, but the widespread presence of micro- and nano-plastics (MNPs) poses significant threats to them. Haematococcus pluvialis is well-known for its ability to produce the antioxidant astaxanthin when it experiences stress from environmental conditions. Here we examined the effects of polystyrene nanoplastics (PS-NPs) at concentrations of 0.1, 1, and 10 mg/L on H. pluvialis over an 18-day period. Our results show that PS-NPs caused a significant, dose-dependent inhibition of H. pluvialis growth and a reduction in photosynthesis. Furthermore, PS-NPs severely damaged the morphology of H. pluvialis, leading to cell shrinkage, collapse, content release, and aggregation. Additionally, PS-NPs induced a dose-dependent increase in soluble protein content and a decrease in the production of extracellular polymeric substances. These findings indicate that PS-NPs has the potential to adversely affect both the physiology and morphology of H. pluvialis. An increase in reactive oxygen species and antioxidant enzyme activities was also observed, suggesting an oxidative stress response to PS-NPs exposure. Notably, the synthesis of astaxanthin, which is crucial for H. pluvialis's survival under stress, was significantly inhibited in a dose-dependent manner under strong light conditions, along with the down-regulation of genes involved in the astaxanthin biosynthesis pathway. This suggests that PS-NPs exposure reduces H. pluvialis's ability to survive under adverse conditions. This study enhances our understanding of the toxic effects of PS-NPs on microalgae and underscores the urgent need for measures to mitigate MNP pollution to protect aquatic ecosystems.

Effect of biodegradable and conventional microplastic exposure in combination with seawater inundation on the coastal terrestrial plant Plantago coronopus

Coastal ecosystems face a multitude of pressures including plastic pollution and increased flood risk due to sea level rise and the frequency and severity of storms. Experiments seldom examine multiple stressors such as these, but here we quantified the effect of microplastics (polyethylene terephthalate (PET): a durable plastic and polybutylene adipate terephthalate (PBAT): a biodegradable polymer), in combination with simulated seawater inundation on the coastal species Plantago coronopus. After 35-days exposure to plastic (0.02 g.Kg-1, <300 μm diameter), P. coronopus were flooded to pot height with artificial seawater for 72-h, drained and grown for a further 24-days. Plant mortality, necrosis and photosynthetic efficiency (Fv/Fm) were recorded throughout, with root:shoot biomass and scape production (flower stalks) quantified at harvest. There were significant interactions between microplastics and seawater on the root:shoot ratio; a measure of resource allocation. The allocation to belowground biomass increased significantly under the PET + inundation treatment compared to the PBAT + inundation and the no plastic + inundation treatments, with potential consequences on the capture of water, nutrients and sunlight, which can affect plant performance. Plant necrosis significantly increased, and Fv/Fm declined as a result of seawater inundation. While not significant, plant Fv/Fm responses were influenced by microplastics (17% and 7% reduction in PBAT and PET exposure respectively compared to the no plastic control). Plants mediated this stress response with no discernible treatment-specific effects detected in Fv/Fm 14-days after seawater introduction. Plastic exposure significantly influenced potential reproductive output, with lower average scape numbers across PBAT treatments, but higher in PET treatments. This study highlights the complex interactions and potential for microplastics to present an elevated risk when in combination with additional stressors like seawater flooding; establishing the threat presented to ecosystem resilience in a changing world is a priority.

Time dependent release of microplastics from disposable face masks poses cyto-genotoxic risks in Allium cepa

The use of disposable face masks (DFMs) increased during the COVID-19 pandemic and has become a threat to the environment due to the release of microplastics (MPs). Although many reports have characterized and explored the release of MPs from DFMs and their effects in aquatic ecosystems, there is a lack of investigation into the effects in terrestrial plants. This report aims to fill this research gap by characterizing whole mask leachates (WMLs) collected at different time points and examining their toxicity on Allium cepa, a terrestrial model plant. Various analytical techniques including FE-SEM, FT-IR, and Raman spectroscopy were used to identify MPs in WMLs. The MPs are composed of polypropylene mostly and the concentration of smaller-sized MPs increased with leachate release time. The WMLs showed a MP concentration-dependent cytogenotoxic effect (72 %, 50 %, and 31 %, on 1, 5, and 11-day WMLs, respectively) on A. cepa root cells due to elevated oxidative stress (19 %, 45 %, and 70 %, on 1, 5, and 11-day WMLs, respectively). Heavy metal content of the WMLs was negligible and, thus, not a significant contributor to toxicity in the plant. Overall, this report highlights the fate of DFMs in the environment and their biological impacts in a model plant.

Impact of aged and virgin polyethylene microplastics on multi end-points effects of freshwater fish tissues

The buildup of plastic waste in aquatic environments presents serious threats to the environment, wildlife, and ultimately to humans. Specifically, microplastics (MPs) ingestion by aquatic animals leads to adverse physiological and toxicological effects. In addition, discarded MPs undergo aging and degradation processes which affect their morphological properties and chemical composition, enhancing the absorption of environmental pollutants. Under this prism, the present research was conducted to investigate and compare the impact of 'aged' versus pristine low-density polyethylene microplastics (PE-MPs) on various toxicity endpoints as biochemical and molecular parameters in the muscle tissue and liver of the freshwater fish species Perca fluviatilis. In parallel, the morphological, physicochemical, and structural changes occurred in "aged" PE-MPs, (after being exposed to UV radiation for 120 days) were studied, significantly illustrating signs of oxidation and crack propagation at the surface of the studied MPs. Fish were exposed to artificial diet reached with virgin and "aged" PE-MPs, sized 100-180 μm, at concentrations of 1 mg/g of dry food for a period of 15-days. Thereafter, liver and muscle tissues were analyzed in relation to multi oxidative parameters. Compared to the control group, the observed changes in the examined fish included increased activities of antioxidant enzymes, as superoxide dismutase, catalase and glutathione reductase, enhanced concentrations of malondialdehyde, protein carbonylation, HSP70 levels, elevated MAPK phosphorylation, induction of ubiquitin-proteins, as well as heightened levels of Bax/Bcl-2 proteins, caspases and differentiated levels of LC3 II/I, SQSTM1/p62. From the studied biomarkers, apoptosis, ubiquitin and hsp70 levels, showed a more sensitive response against the ingested MPs, followed by autophagy, p38MAPK levels, antioxidant enzymes, MDA and carbonylation levels. The effect of "aged" PE-MPs was more pronounced compared to that of the virgin ones. When evaluating the response of all oxidative stress biomarkers across the studied tissues, the liver demonstrates the highest response for the majority of the biomarkers against both virgin and "aged" PE-MPs. These findings strongly indicate that "aged" MPs activate the antioxidant defence mechanisms and impact the cellular well-being of the examined fish species.

Effects of biodegradable (PBAT/PLA) and conventional (LDPE) mulch film residues on bacterial communities and metabolic functions in different agricultural soils

Soil health is a crucial aspect of sustainable agriculture and food production, necessitating attention to the ecological risks associated with substantial amounts of mulch film residues. Biodegradable mulch films (BDMs) carry the same risk of mulch film residues formation as low-density polyethylene (LDPE) mulch films during actual use. More information is needed to elucidate the specific impacts of mulch film residues on the soil environment. Integrated 16S rRNA gene sequencing and non-targeted metabolomics, this study revealed the response patterns of bacterial communities, metabolites, and metabolic functions in the soil from three different agricultural regions to the presence of mulch film residues. LDPE mulch film residues negatively impacted the bacterial communities in the soils of Heilongjiang (HLJ) and Yunnan (YN) and had a lesser impact on the metabolic spectrum in the soils of HLJ, YN, and Xinjiang (XJ). BDM residues had a greater negative impact on all three soils in terms of both the bacterial communities and metabolites. The impact of BDM treatment on the soils of HLJ, YN, and XJ increased sequentially in that order. It is recommended that, when promoting the use of biodegradable mulch films, a fuller assessment should be made, accounting for local soil properties.

Persistent Luminescence Nanoplatform for Autofluorescence-Free Tracking of Submicrometer Plastic Particles in Plant

The uptake of plastic particles by plants and their transport through the food chain make great risks to biota and human health. Therefore, it is important to trace plastic particles in the plant. Traditional fluorescence imaging in plants usually suffers significant autofluorescence background. Here, we report a persistent luminescence nanoplatform for autofluorescence-free imaging and quantitation of submicrometer plastic particles in plant. The nanoplatform was fabricated by doping persistent luminescence nanoparticles (PLNPs) onto polystyrene (PS) nanoparticles. Cr3+-doped zinc gallate PLNP was employed as the dopant for autofluorescence-free imaging due to its persistent luminescence nature. In addition, the Ga element in PLNP was used as a proxy to quantify the PS in the plant by inductively coupled plasma mass spectrometry (ICP-MS). Thus, the developed nanoplatform allows not only dual-mode autofluorescence-free imaging (persistent luminescence and laser-ablation ICP-MS) but also ICP-MS quantitation for tracking PS in plant. Application of this nanoplatform in a typical plant model Arabidopsis thaliana revealed that PS mainly distributed in the root (>99.45%) and translocated very limited (<0.55%) to the shoot. The developed nanoplatform has great potential for quantitative tracing of submicrometer plastic particles to investigate the environmental process and impact of plastic particles.

Unveiling the impact of microplastics and nanoplastics on vascular plants: A cellular metabolomic and transcriptomic review

With increasing plastic manufacture and consumption, microplastics/nanoplastics (MP/NP) pollution has become one of the world's pressing global environmental issues, which poses significant threats to ecosystems and human health. In recent years, sharp increasing researches have confirmed that MP/NP had direct or indirect effects on vegetative growth and sexual process of vascular plant. But the potential mechanisms remain ambiguous. MP/NP particles can be adsorbed and/or absorbed by plant roots or leaves and thus cause diverse effects on plant. This holistic review aims to discuss the direct effects of MP/NP on vascular plant, with special emphasis on the changes of metabolic and molecular levels. MP/NP can alter substance and energy metabolism, as well as shifts in gene expression patterns. Key aspects affected by MP/NP stress include carbon and nitrogen metabolism, amino acids biosynthesis and plant hormone signal transduction, expression of stress related genes, carbon and nitrogen metabolism related genes, as well as those involved in pathogen defense. Additionally, the review provides updated insights into the growth and physiological responses of plants exposed to MP/NP, encompassing phenomena such as seed/spore germination, photosynthesis, oxidative stress, cytotoxicity, and genotoxicity. By examining the direct impact of MP/NP from both physiological and molecular perspectives, this review sets the stage for future investigations into the complex interactions between plants and plastic pollutants.

A metabolomics perspective on the effect of environmental micro and nanoplastics on living organisms: A review

The increasing trend regarding the use of plastics has arisen an exponential concern on the fate of their derived products to the environment. Among these derivatives, microplastics and nanoplastics (MNPs) have been featured for their associated environmental impact due to their low molecular size and high surface area, which has prompted their ubiquitous transference among all environmental interfaces. Due to the heterogenous chemical composition of MNPs, the study of these particles has focused a high number of studies, as a result of the myriad of associated physicochemical properties that contribute to the co-transference of a wide range of contaminants, thus becoming a major challenge for the scientific community. In this sense, both primary and secondary MNPs are well-known to be adscribed to industrial and urbanized areas, from which they are massively released to the environment through a multiscale level, involving the atmosphere, hydrosphere, and lithosphere. Consequently, much research has been conducted on the understanding of the interconnection between those interfaces, that motivate the spread of these contaminants to biological systems, being mostly represented by the biosphere, especially phytosphere and, finally, the anthroposphere. These findings have highlighted the potential hazardous risk for human health through different mechanisms from the environment, requiring a much deeper approach to define the real risk of MNPs exposure. As a result, there is a gap of knowledge regarding the environmental impact of MNPs from a high-throughput perspective. In this review, a metabolomics-based overview on the impact of MNPs to all environmental interfaces was proposed, considering this technology a highly valuable tool to decipher the real impact of MNPs on biological systems, thus opening a novel perspective on the study of these contaminants.

Comparative analysis of the effects of microplastics and nitrogen on maize and wheat: Growth, redox homeostasis, photosynthesis, and AsA-GSH cycle

Microplastics (MPs) pose a significant threat to the function of agro-ecosystems. At present, research on MPs has mainly focused on the effects of different concentrations or types of MPs on a crop, while ignoring other environmental factors. In agricultural production, the application of nitrogen (N) fertilizer is an important means to maintain the high yield of crops. The effects of MPs and N on growth parameters, photosynthetic system, active oxygen metabolism, nutrient content, and ascorbate-glutathione (AsA-GSH) cycle of maize and wheat were studied in order to explicit whether N addition could effectively alleviate the effects of MPs on maize and wheat. The results showed that MPs inhibited the plant height of both maize and wheat, and MPs effects on physiological traits of maize were more severe than those of wheat, reflecting in reactive oxygen metabolism and restriction of photosynthetic capacity. Under the condition of N supply, AsA-GSH cycle of two plants has different response strategies to MPs: Maize promoted enzyme activity and co-accumulation of AsA and GSH, while wheat tended to consume AsA and accumulate GSH. N application induced slight oxidative stress on maize, which was manifested as an increase in hydrogen peroxide and malonaldehyde contents, and activities of polyphenol oxidase and peroxidase. The antioxidant capacity of maize treated with the combination of MPs + N was better than that treated with N or MPs alone. N could effectively alleviate the adverse effects of MPs on wheat by improving the antioxidant capacity.

Effect and environmental behaviour of microplastics in soil

Soil microplastic pollution is currently a worldwide concern. Microplastics are organic pollutants that are abundant in the natural environment, are persistent and difficult to degrade and may endanger human health while harming the environment. This article offers a bibliometric analysis of the environmental behaviour of microplastics in soils, as well as a thorough statistical analysis of research goals and trends in this field. We conducted a thorough search of all relevant literature from 2012 to 2022 in the Web of Science core database. The data analysis shows that, starting in 2012, there has been an upward trend in the number of articles about soil microplastic pollution. It can also be seen that China is relatively ahead of the curve in this area of research, followed by the United Kingdom and the United States. This article also systematically describes the research hotspots in this field. The results show that the current research on soil microplastics is mainly focused on their identification, enrichment and toxicity, whereas studies on the migration and transformation of soil microplastics and the mechanism of interaction with other pollutants are still lacking. Our results provide ideas and prospects for future research in this field.

Micro- and nanoplastics in agricultural soils: Assessing impacts and navigating mitigation

Micro-/nanoplastic contamination in agricultural soils raises concerns on agroecosystems and poses potential health risks. Some of agricultural soils have received significant amounts of micro-/nanoplastics (MNPs) through plastic mulch film and biosolid applications. However, a comprehensive understanding of the MNP impacts on soils and plants remains elusive. The interaction between soil particles and MNPs is an extremely complex issue due to the different properties and heterogeneity of soils and the diverse characteristics of MNPs. Moreover, MNPs are a class of relatively new anthropogenic pollutants that may negatively affect plants and food. Herein, we presented a comprehensive review of the impacts of MNPs on the properties of soil and the growth of plants. We also discussed different strategies for mitigating or eliminating MNP contamination. Moreover, perspectives for future research on MNP contamination in the agricultural soils are also highlighted.

Environmental impact of microplastics and potential health hazards

Microscopic plastic (microplastic) pollutants threaten the earth's biodiversity and ecosystems. As a result of the progressive fragmentation of oversized plastic containers and products or manufacturing in small sizes, microplastics (particles of a diameter of 5 mm with no lower limit) are used in medicines, personal care products, and industry. The incidence of microplastics is found everywhere in the air, marine waters, land, and even food that humans and animals consume. One of the greatest concerns is the permanent damage that is created by plastic waste to our fragile ecosystem. The impossibility of the complete removal of all microplastic contamination from the oceans is one of the principal tasks of our governing body, research scientists, and individuals. Implementing the necessary measures to reduce the levels of plastic consumption is the only way to protect our environment. Cutting off the plastic flow is the key remedy to reducing waste and pollution, and such an approach could show immense significance. This review offers a comprehensive exploration of the various aspects of microplastics, encompassing their composition, types, properties, origins, health risks, and environmental impacts. Furthermore, it delves into strategies for comprehending the dynamics of microplastics within oceanic ecosystems, with a focus on averting their integration into every tier of the food chain.

Polystyrene nanoplastics distinctly impact cadmium uptake and toxicity in Arabidopsis thaliana

The ubiquitous presence of micro- and nanoplastics (MNPs) in soil has raised concerns regarding their potential effects on terrestrial plants. The coexistence and interactions between MNPs and heavy metals altering their phytotoxicity deserves further investigation. In this study, we explored the impacts of various concentrations of polystyrene nanoplastics (PS-NPs) and cadmium (Cd) alone or in combination on the growth and development of Arabidopsis thaliana. Additionally, we examined the effects of combined stress on the uptake and translocation of Cd within Arabidopsis thaliana. Our findings revealed several key insights: PS-NPs exhibited the capability to internalize in the maturation zone of Arabidopsis roots; the presence of Cd changed the particle size and zeta potential of PS-NPs; the presence of PS-NPs heightened Cd accumulation in the underground parts of Arabidopsis seedlings, leading to a stronger oxidative stress response in these regions; the composite stress exerted a more pronounced effect on the growth and development of Arabidopsis compared to individual stresses. Interestingly, while higher PS-NPs concentrations hindered Cd migration from roots to leaves, they also acted as carriers for Cd uptake in Arabidopsis roots. These findings shed light on the combined impacts of MNPs and heavy metals on plant physiology, offering theoretical insights to guide risk assessment strategies for MNPs and heavy metals in terrestrial ecosystems.

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.

Effects of microplastics and cadmium co-contamination on soil properties, maize (Zea mays L.) growth characteristics, and cadmium accumulation in maize in loessial soil-maize systems

Microplastics (MPs) are pervasive pollutants found in agricultural soils, yet research on the combined impacts of MPs and heavy metals on soil-plant systems remains limited. This study investigates the combined impact of low-density polyethylene (LDPE) microplastics (L: 1 mm, S: 100 μm, 0.1%, 1%) and Cd on soil properties, available Cd content, maize growth, and Cd accumulation by mazie through pot experiments. The findings unveiled notable impacts of the treatment groups, namely MP-L0.1%, MP-S0.1%, MP-L1%, and MP-S1%, on soil organic carbon (SOC), maize height, and catalase (CAT) activity (P < 0.05). The dosage of MPs significantly influenced maize height, MP-S0.1% treatment resulted in a 5.6% reduction, while the other groups had insignificant effects. Particle size and dosage significantly affected SOC and CAT (P < 0.01). The MP-L1% and MP-S1% groups resulted in increases of SOC by 121.5% and 281.0%, respectively. CAT reductions were 32.6%, 62.8%, 41.9%, and 34.9% in MP-L0.1%, MP-S0.1%, MP-L1%, and MP-S1% groups, individually. The Cd treatment induced a significant decrease in soil cation exchange capacity (CEC), maize stem diameter, and root length, accompanied by significant increases in maize plant height, malondialdehyde (MDA), CAT, and superoxide dismutase (SOD) activities. Combined LDPE and Cd contamination had significant effects on maize height and Cd content in leaves. Specifically, MP-L0.1%+Cd, MP-S0.1%+Cd, MP-L1%+Cd, and MP-S1%+Cd reduced maize height by 4.1%, 4.5%, 8.7%, and 13.8%, respectively. The co-presence of LDPE and Cd increased available Cd content in soil while elevating Cd concentration in maize shoots and roots, with a notable 25.5% increase in Cd concentration in maize leaves in the MP-L1%+Cd group compared to the Cd group. Furthermore, LDPE effects on soil-plant systems varied depending on particle size and dosage. This research provides important perspectives on evaluating the concurrent contamination and potential dangers of MPs and toxic metals in soil-plant environments.

Coupling hyperspectral imaging with machine learning algorithms for detecting polyethylene (PE) and polyamide (PA) in soils

Soil, particularly in agricultural regions, has been recognized as one of the significant reservoirs for the emerging contaminant of MPs. Therefore, developing a rapid and efficient method is critical for their identification in soil. Here, we coupled HSI systems [i.e., VNIR (400-1000 nm), InGaAs (800-1600 nm), and MCT (1000-2500 nm)] with machine learning algorithms to distinguish soils spiked with white PE and PA (average size of 50 and 300 µm, respectively). The soil-normalized SWIR spectra unveiled significant spectral differences not only between control soil and pure MPs (i.e., PE 100% and PA 100%) but also among five soil-MPs mixtures (i.e., PE 1.6%, PE 6.9%, PA 5.0%, and PA 11.3%). This was primarily attributable to the 1st-3rd overtones and combination bands of C-H groups in MPs. Feature reductions visually demonstrated the separability of seven sample types by SWIR and the inseparability of five soil-MPs mixtures by VNIR. The detection models achieved higher accuracies using InGaAs (92-100%) and MCT (97-100%) compared to VNIR (44-87%), classifying 7 sample types. Our study indicated the feasibility of InGaAs and MCT HSI systems in detecting PE (as low as 1.6%) and PA (as low as 5.0%) in soil. SYNOPSIS: One of two SWIR HSI systems (i.e., InGaAs and MCT) with a sample imaging surface area of 3.6 mm² per grid cell was sufficient for detecting PE (as low as 1.6%) and PA (as low as 5.0%) in soils without the digestion and separation procedures.

The retention of plastic particles by macrophytes in the Amazon River, Brazil

This study evaluated the presence of plastics and microplastics in macrophytes in an urbanized sector of the Amazon River. A total of 77 quadrats in 23 macrophyte banks were sampled during the dry (September 2020) and rainy (June 2021) season. Five species were identified: Paspalum repens, Pontederia rotundifolia, Pistia stratiotes, Salvinia auriculata and Limnobium laevigatum, with P. repens being dominant during the dry season (47.54%) and P. rotundifolia during the rainy season (78.96%). Most of the plastic particles accumulated in Paspalum repens (49.3%) and P. rotundifolia (32.4%), likely due to their morphological structure and volume. The dry season showed a higher accumulation of plastic particles than the rainy season. Microplastics were found in most samples, during both the dry (75.98%) and rainy seasons (74.03%). The upstream macrophyte banks retained more plastic particles compared to the downstream banks. A moderate positive correlation was observed between the presence of plastic particles and macrophyte biomass, and a weak positive correlation between the occurrence of microplastics and mesoplastics. White and blue fragments, ranging from 1 to 5 mm were the most common microplastics found in the macrophyte banks. Green fragments and green and blue fibers were identified as polypropylene, blue and red fragments as polyethylene, and white fragments as polystyrene. Therefore, the results of this study highlight the first evidence of the retention of plastic particles in macrophytes of the Amazon and highlight a significant risk due to the harmful effects that this type of plastic can cause to the fauna and flora of aquatic ecosystems.

A Study on the Growth and Physiological Toxicity Effects of the Combined Exposure of Microplastics and Cadmium on the Vicia faba L. Seedlings

To investigate the toxicological effects of polystyrene microplastics (PS-MPs), cadmium (Cd), and their combined contamination on the growth and physiological responses of V. faba seedlings, this experiment employed a hydroponic method. The Hoagland nutrient solution served as the control, changes in root growth, physiological and biochemical indicators of V. faba seedlings under different concentrations of PS-MPs (10, 100 mg/L) alone and combined with 0.5 mg/L Cd. The results demonstrated that the root biomass, root vitality, generation rate of superoxide radicals (O2·-), malondialdehyde (MDA) content, and superoxide dismutase (SOD) activity increased with increasing concentration under the influence of PS-MPs alone, while the soluble sugar content and peroxidase (POD) activity decreased. In the combined treatment with Cd, the trends of these indicators are generally similar to the PS-MPs alone treatment group. However, root vitality and SOD activity showed an inverse relationship with the concentration of PS-MPs. Furthermore, laser confocal and electron microscopy scanning revealed that the green fluorescent polystyrene microspheres entered the root tips of the V. faba and underwent agglomeration in the treatment group with a low concentration of PS-MPs alone and a high concentration of composite PS-MPs with Cd.

The combined toxicity of polystyrene nano/micro-plastics and triphenyl phosphate (TPHP) on HepG2 cells

Combined toxicity is a critical concern during the risk assessment of environmental pollutants. Due to the characteristics of strong hydrophobicity and large specific surface area, microplastics (MPs) and nanoplastics (NPs) have become potential carriers of organic pollutants that may pose a health risk to humans. The co-occurrence of organic pollutants and MPs would cause adverse effects on aquatic organism, while the information about combined toxicity induced by organophosphorus flame retardants and MPs on human cells was limited. This study aimed to reveal the toxicity effects of co-exposure to triphenyl phosphate (TPHP) and polystyrene (PS) particles with micron-size/nano-size on HepG2 cell line. The adsorption behaviors of TPHP on PS particles was observed, with the PS-NP exhibiting a higher adsorption capacity. The reactive oxygen species generation, mitochondrial membrane potential depolarization, lactate dehydrogenase release and cell apoptosis proved that PS-NPs/MPs exacerbated TPHP-induced cytotoxicity. The particle size of PS would affect the toxicity to HepG2 cells that PS-NP (0.07 μm) exhibited more pronounced combined toxicity than PS-MP (1 μm) with equivalent concentrations of TPHP. This study provides fundamental insights into the co-toxicity of TPHP and PS micro/nanoplastics in HepG2 cells, which is crucial for validating the potential risk of combined toxicity in humans.

Nanoplastic toxicity induces metabolic shifts in Populus × euramericana cv. '74/76' revealed by multi-omics analysis

There is increasing global concern regarding the pervasive issue of plastic pollution. We investigated the response of Populus × euramericana cv. '74/76' to nanoplastic toxicity via phenotypic, microanatomical, physiological, transcriptomic, and metabolomic approaches. Polystyrene nanoplastics (PS-NPs) were distributed throughout the test plants after the application of PS-NPs. Nanoplastics principally accumulated in the roots; minimal fractions were translocated to the leaves. In leaves, however, PS-NPs easily penetrated membranes and became concentrated in chloroplasts, causing thylakoid disintegration and chlorophyll degradation. Finally, oxidant damage from the influx of PS-NPs led to diminished photosynthesis, stunted growth, and etiolation and/or wilting. By integrating dual-omics data, we found that plants could counteract mild PS-NP-induced oxidative stress through the antioxidant enzyme system without initiating secondary metabolic defense mechanisms. In contrast, severe PS-NP treatments promoted a shift in metabolic pattern from primary metabolism to secondary metabolic defense mechanisms, an effect that was particularly pronounced during the upregulation of flavonoid biosynthesis. Our findings provide a useful framework from which to further clarify the roles of key biochemical pathways in plant responses to nanoplastic toxicity. Our work also supports the development of effective strategies to mitigate the environmental risks of nanoplastics by biologically immobilizing them in contaminated lands.

Impact of polyvinyl chloride (PVC) microplastic on growth, photosynthesis and nutrient uptake of Solanum lycopersicum L. (Tomato)

Microplastics (MPs) pollution and their impact on plants have become a global threat, but their effect at the molecular level remains scarce. This study aims to gain insight into the effects of polyvinylchloride microplastic (PVC-MP) on tomato plants at the genetic and protein levels. In this study, we found that increasing concentrations of PVC-MP (2.5, 5,7.5, and 10% w/w) in the soil did not cause any phytotoxic (chlorosis or necrosis) symptoms but it did result in a dose-dependent reduction in plant growth-related parameters, such as height, leaf area, stem diameter, and plant fresh and dry weight. Additionally, the number of secondary roots was reduced while the primary roots were elongated. Furthermore, PVC-MP also caused a significant decrease in light-harvesting pigments chlorophylls, and carotenoids while increasing the level of reactive oxygen species (ROS) and lipid peroxidation in plants. Microscopic analysis of the roots revealed the uptake of PVC-MP of size less than 10 μm. Micro- and macro-element analysis showed changes in concentrations of Ca, Cu, Fe, Mg, Mn, Ni, and Zn, upon PVC-MP exposure. Results from western blotting and q-PCR showed that higher doses of PVC-MP significantly reduced the CO2-fixing enzyme RuBisCO and D1 proteins of PSII at both protein and transcript levels. These findings suggest that lower levels of light-harvesting pigments, D1 protein, RuBisCO, and modulation of nutrient absorption are among the factors responsible for growth suppression in tomato plants upon exposure to PVC-MP. As tomato plants are economically significant crops, an increase in PVC-MP in agricultural fields may have a detrimental influence on crop production, resulting in economic loss.

Brassinolide as potential rescue agent for Pinellia ternata grown under microplastic condition: Insights into their modulatory role on photosynthesis, redox homeostasis, and AsA-GSH cycling

Microplastic (MP), as a new pollutant, not only affects the growth and development of plants but also may affect the secondary metabolites of plants. The anti-tumor role of Pinellia ternata is related to secondary metabolites. The role of brassinolide (BR) in regulating plant resistance is currently one of the research hotspots. The paper mainly explores the regulation of BR on growth and physiology of Pinellia ternata under MP stress. The experimental design includes two levels of MP (0, 1%) and two levels of BR (0, 0.1 mg/L). MP led to a marked reduction in plant height (15.0%), Fv/Fm (3.2%), SOD and APX activity (15.0%, 5.1%), whereas induced an evident raise in the rate of O2·- production (29.6%) and GSH content (4.4%), as well as flavonoids (6.8%), alkaloids (75%), and β-sitosterol (26.5%) contents. Under MP addition, BR supply significantly increased plant height (15.7%), aboveground and underground biomass (16.1%, 10.3%), carotenoid and GSH content (11.8%, 4.2%), Fv/Fm (2.9%), and activities of SOD, GR, and MDHAR (32.2%, 21.08%, 20.9%). These results indicate that MP suppresses the growth of P. ternata, although it promotes secondary metabolism. BR can alleviate the inhibitory effect of MP on growth by improving photosynthesis, redox homeostasis, and the AsA-GSH cycle.

Non-negligible impact of microplastics on wetland ecosystems

There has been much concern about microplastic (MP) pollution in marine and soil environments, but attention is gradually shifting towards wetland ecosystems, which are a transitional zone between aquatic and terrestrial ecosystems. This paper comprehensively reviews the sources of MPs in wetland ecosystems, as well as their occurrence characteristics, factors influencing their migration, and their effects on animals, plants, microorganisms, and greenhouse gas (GHG) emissions. It was found that MPs in wetland ecosystems originate mainly from anthropogenic sources (sewage discharge, and agricultural and industrial production) and natural sources (rainfall-runoff, atmospheric deposition, and tidal effects). The most common types and forms of MPs identified in the literature were polyethylene and polypropylene, fibers, and fragments. The migration of MPs in wetlands is influenced by both non-biological factors (the physicochemical properties of MPs, sediment characteristics, and hydrodynamic conditions) and biological factors (the adsorption and growth interception by plant roots, ingestion, and animal excretion). Furthermore, once MPs enter wetland ecosystems, they can impact the resident microorganisms, animals, and plants. They also have a role in global warming because MPs act as unique exogenous carbon sources, and can also influence GHG emissions in wetland ecosystems by affecting the microbial community structure in wetland sediments and abundance of genes associated with GHG emissions. However, further investigation is needed into the influence of MP type, size, and concentration on the GHG emissions in wetlands and the underlying mechanisms. Overall, the accumulation of MPs in wetland ecosystems can have far-reaching consequences for the local ecosystem, human health, and global climate regulation. Understanding the effects of MPs on wetland ecosystems is essential for developing effective management and mitigation strategies to safeguard these valuable and vulnerable environments.

Effect of cadmium on polystyrene transport in parsley roots planted in a split-root system and assessment of the combined toxic effects

Micro and nanoplastics (MPs/NPs) coupled with heavy metals are prevalent in both aquatic and terrestrial ecosystems. Their ecological toxicity and combined adverse effects have obtained significant concern. Past studies primarily focused on how MPs/NPs influence the behavior of heavy metals. Yet, the possible effects of heavy metals on MP/NP transport and toxicity within co-contaminated systems are still not well-understood. In this study, we conducted split-root experiments to explore the transport and toxicity of polystyrene (PS) particles of varying sizes in parsley seedlings, both with and without the addition of cadmium (Cd). Both the PS-NPs (100 nm) and PS-MPs (300 nm) traveled from the PS-spiked roots (Roots-1) to the non-PS-spiked roots (Roots-2), with or without Cd, possibly because of phloem transport. Furthermore, the presence of Cd reduced the accumulation and movement of PS-NP/MP in the roots, likely due to the increased positive charge (Cd2+) on the PS surface. PS-NPs/MPs in both Roots-1 and Roots-2 were observed using transmission electron microscopy (TEM). When Cd was added to either Roots-1 (PS + Cd|H) or Roots-2 (PS|Cd), there was a minor reduction in the chlorophyll a and carotenoids content in leaves with PS|H. The adverse impacts of MPs|H on both indicators were influenced by the MP concentration. However, chlorophyll b significantly increased in the PS|H, PS + Cd|H, and PS|Cd treatments. Consequently, the chlorophyll a/b ratio declined, indicating inhibition of photosynthesis. The dehydrogenase content showed a minor change in Roots-1 and Roots-2 without Cd stress, whereas it significantly decreased on the Cd-spiked side and subsequently inhibited root growth. In contrast, the marked rise in glutathione (GSH) levels within Cd-spiked roots suggested, based on Gaussian analysis, that GSH and Cd chelation were instrumental in mitigating Cd toxicity. When Cd was introduced to both Roots-1 and Roots-2 simultaneously (PS + Cd|Cd), the aforementioned index showed a notable decline.

Atmospheric microplastic deposition associated with GDP and population growth: Insights from megacities in northern China

Microplastic (MP) pollution is evolving into one of the most pressing environmental concerns worldwide. This study assessed the impact of economic activities on atmospheric MP pollution across 17 megacities in northern China, analyzing the correlation between the deposition flux of atmospheric MPs and variables such as city population, gross domestic product (GDP), and industrial structure. The results have shown that the MP pollution is obviously impacted by human activities related to increased GDP, population, as well as tertiary service sector, in which the MP pollution shows most close relationship with the GDP growth. Polypropylene, polyamide, polyurethane, and polyethylene were identified as the primary components of atmospheric MPs. The average particle size of MPs in atmospheric dustfall is 78.3 µm, and the frequency of MP particles increases as the particle size decreases. The findings highlight the complex relationship between socio-economic development and atmospheric MP accumulation, providing essential insights for the formulation of targeted emission reduction strategies.

Physiological and biochemical effects of polystyrene micro/nano plastics on Arabidopsis thaliana

Microplastics have garnered global attention due to their potential ecological risks. Research shows micro/nano-plastics pollution has adverse effects on plant growth, development, and physiological characteristics. However, the mechanisms underlying these effects remain unclear. The study examined the effects of polystyrene micro/nano-plastics with varying sizes and concentrations on different physiological and biochemical markers of A. thaliana. The indicators assessed include seed viability, growth, chlorophyll content, accumulation of root reactive oxygen species, and root exudates. Using fluorescence labeling, we investigated the absorption and translocation processes of micro/nano-plastics in A. thaliana. We also performed transcriptomic analysis to better understand the particular mechanisms of micro/nano-plastics. It indicated that micro/nano-plastics had an adverse effect on seed germination, especially under high concentration and small particle size treatments. This effect diminished with prolonged exposure. High concentrations at 50 nm and 100 nm treatment groups significantly inhibited the growth. Conversely, low concentrations of 1000 nm had a promoting effect. Exposure to micro/nano-plastics potentially resulted in decreased chlorophyll content, the accumulation of H2O2 in roots, and stimulated root secretion of oxalic acid. Through transcriptomic analysis, the gene expression linked to micro/nano-plastic treatments of varying sizes enriched multiple metabolic pathways, impacting plant growth, development, environmental adaptation, metabolism, pigment synthesis, and stress response.