Microplastics interaction with terrestrial plants and their impacts on agriculture

Coexistence of microplastics and heavy metals in soil: occurrence, transport, key interactions and effect on plants

Microplastics (MPs) pollution has raised serious environmental concerns due to its widespread generation and discharge across global ecosystems. It is estimated that approximately 400 million metric tons of plastic are produced annually, with 54% ending up as waste. The MPs account for a significant portion of this pollution. These MPs interact with heavy metals (HMs) in terrestrial ecosystems, such as cadmium (Cd), lead (Pb), and arsenic (As), which are introduced through various industrial activities at rates of thousands of tons per year. Such interactions may cause synergistic or antagonistic effects on plants. Recent studies suggest that MPs and HMs exposure impacts various physiological and biochemical pathways in plants, thereby increasing the toxicity symptoms. However, the existing scholarly understanding of the coupled effect of HMs and MPs on plants is limited, highlighting the need to explore these complex dynamics further. Through a comprehensive analysis of current research, this review underscores various pathways of MPs and HMs infiltration mechanisms, detailing their penetration, translocation, and bioaccumulation within plants. The physiological and biochemical effects of both pollutants on plants are deliberated individually and in combination. The review reveals that the co-existence of these contaminants results in a multifaceted environmental challenge, affecting overall plant growth, yield, and quality in ways that differ from individual exposure. Building on recent advancements, this article is expected to delineate the complex interactions between MPs, HMs, and plants and enhance the current understanding of the intricate interplay between them.

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.

Combined effects of polyamide microplastic and sulfamethoxazole in modulating the growth and transcriptome profile of hydroponically grown rice (Oryza sativa L.)

The use of reclaimed water from wastewater treatment plants for irrigation has a risk of introducing micropollutants such as microplastics (MPs) and antimicrobials (AMs) into the agroecosystem. This study was conducted to investigate the effects of single and combined treatment of 0.1 % polyamide (PA ∼15 μm), and varying sulfamethoxazole (SMX) levels 0, 10, 50, and 150 mg/L on rice seedlings (Oryza sativa L.) for 12 days. The study aimed to assess the impact of these contaminants on the morphological, physiological, and biochemical parameters of the rice plants. The findings revealed that rice seedlings were not sensitive to PA alone. However, SMX alone or in combination with PA, significantly inhibited shoot and root growth, total biomass, and affected photosynthetic pigments. Higher concentrations of SMX increased antioxidant enzyme activity, indicating oxidative stress. The roots had a higher SMX content than the shoots, and the concentration of minerals such as iron, copper, and magnesium were reduced in roots treated with SMX. RNA-seq analysis showed changes in the expression of genes related to stress, metabolism, and transport in response to the micropollutants. Overall, this study provides valuable insights on the combined impacts of MPs and AMs on food crops, the environment, and human health in future risk assessments and management strategies in using reclaimed water.

Fluorescent carbon dot embedded polystyrene: an alternative for micro/nanoplastic translocation study in leguminous plants

Micro/nanoplastics are widespread in terrestrial ecosystem. Even though many studies have been reported on the effects of these in marine environment, studies concerning their accumulation and impact on terrestrial ecosystem have been scanty. The current study was designed to determine how terrestrial plants, especially legumes, interact with micro/nanoplastics to gain insights into their uptake and translocation. The paper describes the synthesis of fluorescent carbon dot embedded polystyrene (CDPS) followed by its characterization. Translocation studies at different concentrations from 2 to 100% (v/v) for tracking the movement and accumulation of microplastics in Vigna radiata and Vigna angularis were performed. The optical properties of the synthesized CDPS were investigated, and their translocation within the plants was visualized using fluorescence microscopy. These findings were further validated by scanning electron microscopy (SEM) imaging of the plant sections. The results showed that concentrations higher than 6% (v/v) displayed noticeable fluorescence in the vascular region and on the cell walls, while concentrations below this threshold did not. The study highlights the potential of utilizing fluorescent CDPS as markers for investigating the ecological consequences and biological absorption of microplastics in agricultural systems. This method offers a unique technique for monitoring and analyzing the routes of microplastic accumulation in edible plants, with significant implications for both food safety and environmental health.

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.

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.

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.

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.

Effects of naturally aged microplastics on the distribution and bioavailability of arsenic in soil aggregates and its accumulation in lettuce

Naturally aged microplastics (NAMPs) and arsenic (As) have been reported to coexist in and threaten potentially to soil-plant ecosystem. The research explored the combined toxic effects of NAMPs and As to lettuce (Lactuca sativa L.) growth, and the distribution, accumulation and bioavailability of As in soil aggregates. The As contaminated soil with low, medium and high concentrations (L-As, M-As, H-As) were treated with or without NAMPs, and a total of six treatments. The results displayed that, in comparison to separate treatments of L-As and M-As, the presence of NAMPs increased the total biomass of lettuce grown at these two As concentrations by 68.9 % and 55.4 %, respectively. Simultaneous exposure of NAMPs and L-As or M-As led to a decrease in As content in shoot (0.45-2.17 mg kg-1) and root (5.68-14.66 mg kg-1) of lettuce, indicating an antagonistic effect between them. In contrast, co-exposure to H-As and NAMPs showed synergistic toxicity, and the leaf chlorophyll and nutritional quality of lettuce were also reduced. NAMPs altered the ratio of different soil aggregate fractions and the distribution of bioavailable As within them, which influenced the absorption of As by lettuce. In conclusion, these direct observations assist us in enhancing the comprehend of the As migration and enrichment characteristics in soil-plant system under the influence of NAMPs.

Mechanistic understanding on the uptake of micro-nano plastics by plants and its phytoremediation

Contaminated soil is one of today's most difficult environmental issues, posing serious hazards to human health and the environment. Contaminants, particularly micro-nano plastics, have become more prevalent around the world, eventually ending up in the soil. Numerous studies have been conducted to investigate the interactions of micro-nano plastics in plants and agroecosystems. However, viable remediation of micro-nano plastics in soil remains limited. In this review, a powerful in situ soil remediation technology known as phytoremediation is emphasized for addressing micro-nano-plastic contamination in soil and plants. It is based on the synergistic effects of plants and the microorganisms that live in their rhizosphere. As a result, the purpose of this review is to investigate the mechanism of micro-nano plastic (MNP) uptake by plants as well as the limitations of existing MNP removal methods. Different phytoremediation options for removing micro-nano plastics from soil are also described. Phytoremediation improvements (endophytic-bacteria, hyperaccumulator species, omics investigations, and CRISPR-Cas9) have been proposed to enhance MNP degradation in agroecosystems. Finally, the limitations and future prospects of phytoremediation strategies have been highlighted in order to provide a better understanding for effective MNP decontamination from soil.

Uptake and transport of micro/nanoplastics in terrestrial plants: Detection, mechanisms, and influencing factors

The pervasive dispersion of micro/nanoplastics in various environmental matrices has raised concerns regarding their potential intrusion into terrestrial ecosystems and, notably, plants. In this comprehensive review, we focus on the interaction between these minute plastic particles and plants. We delve into the current methodologies available for detecting micro/nanoplastics in plant tissues, assess the accumulation and distribution of these particles within roots, stems, and leaves, and elucidate the specific uptake and transport mechanisms, including endocytosis, apoplastic transport, crack-entry mode, and stomatal entry. Moreover, uptake and transport of micro/nanoplastics are complex processes influenced by multiple factors, including particle size, surface charge, mechanical properties, and physiological characteristics of plants, as well as external environmental conditions. In conclusion, this review paper provided valuable insights into the current understanding of these mechanisms, highlighting the complexity of the processes and the multitude of factors that can influence them. Further research in this area is warranted to fully comprehend the fate of micro/nanoplastics in plants and their implications for environmental sustainability.

Environmental fate, aging, toxicity and potential remediation strategies of microplastics in soil environment: Current progress and future perspectives

Microplastics (MPs) are small plastic debris (<5 mm) that result from the fragmentation of plastic due to physical and physiochemical processes. MPs are emerging pollutants that pose a significant threat to the environment and human health, primarily due to their pervasive presence and potential bioaccumulation within the food web. Despite their importance, there is a lack of comprehensive studies on the fate, toxicity, and aging behavior of MPs. Therefore, this review aims to address this gap by providing a cohesive understanding of several key aspects. Firstly, it summarizes the sources and fate of MPs, highlighting their ubiquitous presence and the potential pathways through which they enter ecosystems. Secondly, it evaluates the aging process of MPs and the factors influencing it, including the morphological and physiological changes observed in crops and the release of pollutants from aged MPs, which can have detrimental effects on the environment and human health. Furthermore, the impacts of aging MPs on various processes are discussed, such as the mobilization of other pollutants in the environment. The influence of aged MPs on the soil environment, particularly their effect on heavy metal adsorption, is examined. Finally, the review explores strategies for the prevention technologies and remediation of MPs, highlighting the importance of developing effective approaches to tackle this issue. Overall, this review aims to contribute to our understanding of MPs, their aging process, and their impacts on the environment and human health. It underscores the urgency of addressing the issue of MPs and promoting research and remediation efforts to mitigate their adverse effects.

Bibliometric analysis and systematic review of the adherence, uptake, translocation, and reduction of micro/nanoplastics in terrestrial plants

Micro/nanoplastics are emerging agricultural pollutants globally. Micro/nanoplastics can adhere to terrestrial plant surfaces, be absorbed and transported by plants, and accumulate in the edible parts of plants, leading to the possibility of enrichment and transmission through the food chain and threatening human health. However, the underlying mechanism remains unclear. With increased studies on the internalization of micro/nanoplastics in terrestrial plants, a comprehensive and systematic review summarizing the current research trends and progress is warranted to provide a reference for further relevant research. Based on bibliometric analysis, this study focused on the mechanisms, study methods, and reduction techniques of micro/nanoplastics adherence, uptake, and translocation by terrestrial plants. The results showed that micro/nanoplastics can adhere to the surfaces of plant tissues such as seeds, roots, and leaves. Root uptake (root-to-leaf translocation) and foliar uptake (leaf-to-root translocation) are the two simultaneous internalization pathways of MNPs in plants. The observation methods included scanning electron microscopy (SEM), confocal laser scanning microscopy (CLSM), pyrolysis-gas chromatography-mass spectrometry (Py-GC/MS), and inductively coupled plasma-mass spectrometry (ICP-MS). We highlighted the necessity and urgency of reducing the uptake and translocation of MNPs by plants and found that the application of silicon may be a promising approach for reducing internalization. This study identifies current knowledge gaps and proposes possible future needs.

Soils in distress: The impacts and ecological risks of (micro)plastic pollution in the terrestrial environment

Plastics have revolutionised human industries, thanks to their versatility and durability. However, their extensive use, coupled with inadequate waste disposal, has resulted in plastic becoming ubiquitous in every environmental compartment, posing potential risks to the economy, human health and the environment. Additionally, under natural conditions, plastic waste breaks down into microplastics (MPs<5 mm). The increasing quantity of MPs exerts a significant burden on the soil environment, particularly in agroecosystems, presenting a new stressor for soil-dwelling organisms. In this review, we delve into the effects of MP pollution on soil ecosystems, with a specific attention to (a) MP transport to soils, (b) potential changes of MPs under environmental conditions, (c) and their interaction with the physical, chemical and biological components of the soil. We aim to shed light on the alterations in the distribution, activity, physiology and growth of soil flora, fauna and microorganisms in response to MPs, offering an ecotoxicological perspective for environmental risk assessment of plastics. The effects of MPs are strongly influenced by their intrinsic traits, including polymer type, shape, size and abundance. By exploring the multifaceted interactions between MPs and the soil environment, we provide critical insights into the consequences of plastic contamination. Despite the growing body of research, there remain substantial knowledge gaps regarding the long-term impact of MPs on the soil. Our work underscores the importance of continued research efforts and the adoption of standardised approaches to address plastic pollution and ensure a sustainable future for our planet.

Dynamic fluctuations in plant leaf interception of airborne microplastics

Plant leaves have been demonstrated to be a crucial sink of airborne microplastics (MPs). However, because of the particular shape of MPs and their relatively weak forces with leaves, the traditional accumulation model used for the adsorption of particulate matter and persistent organic pollutants may not be appropriate for describing the interception of MPs by leaves. Here, we performed a 7-day exploration of the interception of MPs by leaves in downtown Nanning. The abundances and characteristics of leaf-intercepted MPs showed dramatic diurnal fluctuations and interspecies differences (conifers > arbors > shrubs). The fluctuation (Coefficient of Variation (CV) = 0.459; abundances 0.003 ± 0.002 to 0.047 ± 0.005 n·cm-2) was even more drastic than that measured across species (CV = 0.353; 0.06 ± 0.01 to 0.40 ± 0.04 n·cm-2). Further analysis using partial least-squares path modeling demonstrated that stomatal variation and divergence largely dominated diurnal fluctuations and interspecies differences in microplastic interception by leaves, respectively. Our results highlight that the leaf-intercepted MPs is characterized by dynamic fluctuations rather than static equilibrium and reveal the important regulatory roles played by leaf micromorphological structures in intercepting MPs, thus enhancing our understanding of the interactions between terrestrial plants and airborne pollution.

Combined approaches for detecting polypropylene microplastics in crop plants

Microplastics (MPs) pollution in the terrestrial environment causes accumulation in crop plants. Consumption of these plants may have negative effects on human health. Therefore, it is crucial to analyze MPs accumulation in the plants. The aim of this study is to determine polypropylene (PP) particles in plants exposed to label-free PP for 75 days. In order to extract PP from organic matter, a two-step alkaline and wet peroxide oxidation chemical digestion method was applied to the roots, stems, and leaves of maize and wheat. The PP particles in the digested solutions were detected by the Nile red staining method, which has not been used previously in the detection of MPs in plants. Nile red stained PP particles mostly accumulated in the roots of wheat and the stems of maize plants. Statistical analysis revealed that the maize deposited more and larger PP particles regardless of the location. Moreover, the presence of PP particles in the digestion solutions was proved by the heating method. The PP particles on the glass slides were transformed into different shapes due to melting.

Under flooding conditions, controlled-release fertiliser coated microplastics affect the growth and accumulation of cadmium in rice by increasing the fluidity of cadmium and interfering with metabolic pathways

The combined pollution of microplastics (MPs) and Cd can affect plant growth and development and Cd accumulation, with most studies focusing on dryland soil. However, the effects of polyurethane (PU) controlled-release fertiliser coated MPs (PU MPs), which widely exist in rice systems, coupled with Cd on plant growth and Cd accumulation under flooding conditions are still unknown. Therefore, in the present study, in situ techniques were used to systematically study the effects of PU MPs and Cd coupling on the physiological and biochemical performance, metabolomics characteristics, rhizosphere bacterial community, and Cd bioavailability of rice in different soil types (red soil/cinnamon soil). The results showed that the effects of PU MPs on rice growth and Cd accumulation were concentration-dependent, especially in red soil. High PU concentration (1 %) inhibited rice root growth significantly (44 %). The addition of PU MPs inhibited photosynthetically active radiation, net photosynthesis, and transpiration rate of rice, mainly with low concentration (0.1 %) in red soil and high concentration (1 %) in cinnamon soil. PU MPs can enhance the expression of Cd resistance genes (cadC and copA) in soil, enhance the mobility of Cd, and affect the metabolic pathways of metabolites in the rhizosphere soil (red soil: fatty acid metabolism; cinnamon soil: amino acid degradation, heterobiodegradation, and nucleotide metabolism) to promote Cd absorption in rice. Especially in red soil, Cd accumulation in the root and aboveground parts of rice after the addition of high concentration PU (1 %) was 1.7 times and 1.3 times, respectively, that of the control (p < 0.05). Simultaneously, microorganisms can affect rice growth and Cd bioavailability by affecting functional bacteria related to carbon, iron, sulfur, and manganese. The results of the present study provide novel insights into the potential effects of PU MPs coupled with Cd on plants, rhizosphere bacterial communities, and Cd bioavailability.

Palladium-doped and undoped polystyrene nanoplastics in a chronic toxicity test for higher plants: Impact on soil, plants and ammonium oxidizing bacteria

There is a lack of knowledge about the fate and impact of microplastics (MPs) and nanoplastics (NPs), as well as their potential uptake and impact on plants and microorganisms. The predicted environmental concentrations (PEC) of frequent polymers in soils are low, and therefore, difficult to detect with the available techniques, which explains the knowledge gaps. Therefore, model particles (polystyrene particles (PS-P), 343 nm) and palladium (Pd) nanoparticle-doped polystyrene particles (PS-Pd-PS-P, 442 nm) were synthesized, characterized, and subsequently applied to agricultural soils (Cambisol, Podzol, PS target contents: 25 mg kg-1, 75 mg kg-1, 225 mg kg-1). A combination of different techniques, such as inductively coupled plasma-mass spectrometry (ICP-MS), pyrolysis-gas chromatography-mass spectrometry (Pyr-GC-MS), dynamic light scattering (DLS), and scanning electron microscopy (SEM), were used to characterize the particles in the dispersions, soils and plants. The spiked soils were applied to a chronical plant toxicity test with oat (Avena sativa). The applied particle contents could be recovered from both soils by ICP-MS (Pd, 89% - 99%), and Pyr-GC-MS (PS, 73% - 120%). Moreover, non-aggregated particles in soils and on oat roots were visualized through SEM. The ratio obtained for the Pd contents in oat roots to that in the Cambisol (2.2-2.7) and the Podzol (2.3-2.6) implied that particles accumulated on the root surface or in the roots. No Pd was detected in the oat shoots, which indicated that no translocation occurred from the roots to the shoots. Despite particle accumulation at or in the roots, no clear effects on plant growth were observed. Furthermore, the soil microorganisms (Podzol) and the soil water repellency (Cambisol, Podzol) showed no clear monotone concentration-response relationship after exposure to PS-P and PS-Pd-PS-P. The findings are complex and illustrate the urgent need for further sophisticated experimental studies to elucidate the impacts of NPs on physicochemical soil function, plants, and soil organisms. The model PS-P doped with Pd nanoparticles significantly enhanced the development and validation of methods for investigating MPs and NPs in environmental matrices, highlighting their considerable potential for further studies.

Effects of microplastics and arsenic on plants: Interactions, toxicity and environmental implications

Microplastics are emerging pollutants that are ubiquitously present in environment. Occurrence and dispersion of microplastics in the soil can pose a considerable risk to soil health and biodiversity, including the plants grown in the soil. Uptake and bioaccumulation of microplastics can have detrimental effects on different plant species. Additionally, the co-presence of microplastics and arsenic can cause synergistic, antagonistic, or potentiating toxic impacts on plants. However, limited studies are available on the combined effects of microplastics and arsenic on plants. This paper elucidates both the individual and synergistic effects of microplastics and arsenic on plants. At the outset, the paper highlighted the presence and degradation of microplastics in soil. Subsequently, the interactions between microplastics and plants, accumulation, and influences of microplastics on plant growth and metabolism were explained with underlying mechanisms. Combined effects of microplastics and arsenic on plant growth, metabolism, and toxicity were discussed thereafter. Combined toxic effects of microplastics and arsenic on plants can have detrimental implications on environment, ecosystems and biodiversity. Further investigations on food chain and human health are needed in the context of microplastic-arsenic interactions.

Sources, Degradation, Ingestion and Effects of Microplastics on Humans: A Review

Celluloid, the predecessor to plastic, was synthesized in 1869, and due to technological advancements, plastic products appear to be ubiquitous in daily life. The massive production, rampant usage, and inadequate disposal of plastic products have led to severe environmental pollution. Consequently, reducing the employment of plastic has emerged as a pressing concern for governments globally. This review explores microplastics, including their origins, absorption, and harmful effects on the environment and humans. Several methods exist for breaking down plastics, including thermal, mechanical, light, catalytic, and biological processes. Despite these methods, microplastics (MPs, between 1 and 5 mm in size) continue to be produced during degradation. Acknowledging the significant threat that MPs pose to the environment and human health is imperative. This form of pollution is pervasive in the air and food and infiltrates our bodies through ingestion, inhalation, or skin contact. It is essential to assess the potential hazards that MPs can introduce. There is evidence suggesting that MPs may have negative impacts on different areas of human health. These include the respiratory, gastrointestinal, immune, nervous, and reproductive systems, the liver and organs, the skin, and even the placenta and placental barrier. It is encouraging to see that most of the countries have taken steps to regulate plastic particles. These measures aim to reduce plastic usage, which is essential today. At the same time, this review summarizes the degradation mechanism of plastics, their impact on human health, and plastic reduction policies worldwide. It provides valuable information for future research on MPs and regulatory development.

Effects of tidal action on the stability of microbiota, antibiotic resistance genes, and microplastics in the Pearl River Estuary, Guangzhou, China

In this study, the 16S rRNA gene amplicon sequencing technique was used to explore the microbial diversity and differences in the water environment of the Pearl River Estuary in Nansha District with various land use types such as the aquaculture area, industrial area, tourist area, agricultural plantation, and residential area. At the same time, the quantity, type, abundance, and distribution of two types of emerging environmental pollutants, antibiotic resistance genes (ARGs) and microplastics (MPs), are explored in the water samples from different functional areas. The results show that the dominant phyla in the five functional regions are Proteobacteria, Actinobacteria and Bacteroidetes, and the dominant genera are Hydrogenophaga, Synechococcus, Limnohabitans and Polynucleobacter. A total of 248 ARG subtypes were detected in the five regions, belonging to nine classes of ARGs (Aminoglycoside, Beta_Lactamase, Chlor, MGEs, MLSB, Multidrug, Sul, Tet, Van). Blue and white were the dominant MP colors in the five regions; 0.5-2 mm was the dominant MP size, and cellulose, rayon, and polyester comprised the highest proportion of the plastic polymers. This study provides the basis for understanding the environmental microbial distribution in estuaries and the prevention of environmental health risks from ARGs and microplastics.

Impact of starch-based bioplastic on growth and biochemical parameters of basil plants

The recent use of bioplastics in agriculture is considered an ecological choice, aimed at limiting the environmental impact of plastics, in line with the Sustainable Development Goals of the United Nations. However, the impact of bioplastic residues on the environment is unclear as knowledge is lacking. This is the first study investigating the effect of a starch-based bioplastic on the growth and biochemical parameters of basil. Bioplastic was experimentally prepared and added to the soil at 2.5 % (w/w), corresponding to twice the concentration of plastic mulch film residues currently found in cultivated soils, in view of the increasing agricultural use of bioplastics. Basil plants were grown without (controls) and with bioplastic addition for 35 days, under controlled experimental conditions. Compared to the control, plants exposed to bioplastic showed stunted growth (in terms of shoot fresh weight, height, and number of leaves). Significant reductions in the content of chlorophyll, protein, ascorbic acid, and glucose were also observed. Finally, the treatment caused oxidative stress, as evidenced by the increased content of malondialdehyde in the shoots. The addition of bioplastic increased the electrical conductivity and reduced the cation exchange capacity of the cultivation soil. These results suggest that bioplastic in soil may promote the onset of stressful conditions for plant growth in a similar manner to plastic. They will be complemented by further investigations to unravel the mechanisms underlying these responses, involving different doses and types of bioplastics and other crop species.

A review of disposable facemasks during the COVID-19 pandemic: A focus on microplastics release

The COVID-19 epidemic seriously threats the human society and provokes the panic of the public. Personal Protective Equipment (PPE) are widely utilized for frontline health workers to face the ongoing epidemic, especially disposable face masks (DFMs) to prevent airborne transmission of coronavirus. The overproduction and massive utilization of DFMs seriously challenge the management of plastic wastes. A huge amount of DFMs are discharged into environment, potentially induced the generation of microplastics (MPs) owing to physicochemical destruction. The MPs release will pose severe contamination burden on environment and human. In this review, environmental threats of DFMs regarding to DFMs fate in environment and DFMs threats to aquatic and terrestrial species were surveyed. A full summary of recent studies on MPs release from DFMs was provided. The knowledge of extraction and characterizations of MPs, the release behavior, and potential threats of MPs derived from DFMs was discussed. To confront the problem, feasible strategies for control DFMs pollution were analyzed from the perspective of source control and waste management. This review provides a better understanding the threats, fate, and management of DFMs linked to COVID-19 pandemic.

Micro(nano)plastic pollution in terrestrial ecosystem: emphasis on impacts of polystyrene on soil biota, plants, animals, and humans

Pollution with emerging microscopic contaminants such as microplastics (MPs) and nanoplastics (NPs) including polystyrene (PS) in aquatic and terrestrial environments is increasingly recognized. PS is largely used in packaging materials and is dumped directly into the ecosystem. PS micro-nano-plastics (MNPs) can be potentially bioaccumulated in the food chain and can cause human health concerns through food consumption. Earlier MP research has focused on the aquatic environments, but recent researches show significant MP and NP contamination in the terrestrial environments especially agricultural fields. Though PS is the hotspot of MPs research, however, to our knowledge, this systematic review represents the first of its kind that specifically focused on PS contamination in agricultural soils, covering sources, effects, and ways of PS mitigation. The paper also provides updated information on the effects of PS on soil organisms, its uptake by plants, and effects on higher animals as well as human beings. Directions for future research are also proposed to increase our understanding of the environmental contamination of PS in terrestrial environments.

Effects of Polystyrene Microplastics on Human Kidney and Liver Cell Morphology, Cellular Proliferation, and Metabolism

Microplastics have gained much attention due to their prevalence and abundance in our everyday lives. They have been detected in household items such as sugar, salt, honey, seafood, tap water, water bottles, and food items wrapped in plastic. Once ingested, these tiny particles can travel to internal organs such as the kidney and liver and cause adverse effects on the cellular level. Here, human embryonic kidney (HEK 293) cells and human hepatocellular (Hep G2) liver cells were used to examine the potential toxicological effects of 1 μm polystyrene microplastics (PS-MPs). Exposing cells to PS-MPs caused a major reduction in cellular proliferation but no significant decrease in cell viability as determined by the trypan blue assay in both cell lines. Cell viability remained at least 94% for both cell lines even at the highest concentration of 100 μg/mL of PS-MPs. Phase-contrast imaging of both kidney and liver cells exposed to PS-MPs at 72 h showed significant morphological changes and uptake of PS-MP particles. Confocal fluorescent microscopy confirmed the uptake of 1 μm PS-MPs at 72 h for both cell lines. Additionally, flow cytometry experiments verified that more than 70% of cells internalized 1 μm PS-MPs after 48 h of exposure for both kidney and liver cells. Reactive oxygen species (ROS) studies revealed kidney and liver cells exposed to PS-MPs had increased levels of ROS at each concentration and for every time point tested. Furthermore, quantitative reverse transcription polymerase chain reaction (qRT-PCR) analysis at 24 and 72 h revealed that both HEK 293 and Hep G2 cells exposed to PS-MPs lowered the gene expression levels of the glycolytic enzyme, glyceraldehyde-3-phosphate dehydrogenase (GAPDH), and antioxidant enzymes superoxide dismutase 2 (SOD2) and catalase (CAT), thus reducing the potential of SOD2 and CAT to detoxify ROS. These adverse effects of PS-MPs on human kidney and liver cells suggest that ingesting microplastics may lead to toxicological problems on cell metabolism and cell-cell interactions. Because exposing human kidney and liver cells to microplastics results in morphological, metabolic, proliferative changes and cellular stress, these results indicate the potential undesirable effects of microplastics on human health.

Proactive approach to minimize lithium pollution

With the advancements in lithium-ion battery technology, lithium has been extensively used in many electronic products. Lithium usage is expected to increase in the coming decades. Elevated levels of lithium in the environments, including source water and biota, have been recently reported. Lithium can cause soil dispersion and aggerate swelling and can be readily taken up by plants and filter-feeders, potentially causing toxicity to plants, organisms, and human. As learnt from the reactive approach of the Clean Water Act, many emerging pollutants have not been recognized until they have been widespread and reached dangerous levels in the environments. Aftermath cleanup costs are huge, and many of these damages are irreversible. To avoid lithium being the next global contaminant of emerging concern, environmental agencies shall implement proactive regulation and education soon.

Coupled effects of microplastics and heavy metals on plants: Uptake, bioaccumulation, and environmental health perspectives

Microplastic pollution has severe ecological and environmental concerns because of its enormous production and discharge in natural ecosystems worldwide. Microplastics interact with heavy metals and metalloids like arsenic, chromium, copper, cadmium, and lead in soil and can cause detrimental effects on soil structure and microbial activities and subsequently impact the plants and human health. This article focuses on microplastic translocation from soil to plants together with heavy metals. Microplastic exposure impacts biomass, photosynthetic activity, chlorophyll content, root and shoot length in the plants through apoplastic and symplastic pathways. Microplastics can also indirectly affect the plant growth by changing soil nutrient content and microbial community structure. At the same time, microplastics can absorb heavy metals and increase phytotoxicity in plants. However, the current knowledge about the coupled effect of heavy metals and microplastics bioaccumulation in plants is limited. It is postulated that heavy metals and microplastics collectively impact the chlorophyll content, photosynthetic activity, and induction of reactive oxygen species in plants. This work also outlines the environmental health perspectives based on microplastic and heavy metals toxicity and provides a guideline for future research on the coupled effects of heavy metals and microplastics on plants and humans.

Untoward Effects of Micro- and Nanoplastics: An Expert Review of Their Biological Impact and Epigenetic Effects

The production of plastic has dramatically increased in the last 50 y. Because of their stability and durability, plastics are ubiquitously incorporated in both marine and terrestrial ecosystems. Plastic is acted upon by biological, chemical, and physical agents, leading to fragmentation into small pieces [i.e., microplastics (MPs) or nanoplastics (NPs)], classified depending on their size. MPs range from 0.1 to 5000 μm and NPs are fragments between 0.001 to 0.1 μm. MPs and, especially NPs, are easily incorporated into living beings via ingestion. The penetration of MPs and NPs into the food system is an important issue, for both food security and health risk assessment. Ingestion of different MPs and NPs has been associated with different issues in the intestine, such as direct physical damage, increased intestinal permeability, diminished microbiota diversity, and increases in local inflammatory response. However, the potential harmful effects of low-dose dietary plastic are still unclear. Some evidence indicates that intestinal uptake of plastic particles is relatively low and is mostly dependent on the particle's size. However, other evidence highlights that NPs dysregulate key molecular signaling pathways, modify the gut microbiota composition, and may induce important epigenetic changes, including transgenerational effects that might be involved in the onset of many different metabolic disorders. Until now, experiments have been mostly performed on marine organisms, Caenorhabditis elegans, and mouse models, but some research indicates accidental plastic dietary consumption by humans, raising the issue of detrimental health effects of MPs and NPs. This review discusses the impact that MPs and NPs could have on the intestinal tract and the biodistribution and systemic, cellular, and molecular levels. Accumulated evidence of MPs' effects on the human gut suggests that large exposure to MPs and NPs may have phenotypical untoward effects in humans, calling for urgent research in this field.

Bioanalytical approaches for the detection, characterization, and risk assessment of micro/nanoplastics in agriculture and food systems

This review discusses the most recent literature (mostly since 2019) on the presence and impact of microplastics (MPs, particle size of 1 μm to 5 mm) and nanoplastics (NPs, particle size of 1 to 1000 nm) throughout the agricultural and food supply chain, focusing on the methods and technologies for the detection and characterization of these materials at key entry points. Methods for the detection of M/NPs include electron and atomic force microscopy, vibrational spectroscopy (FTIR and Raman), hyperspectral (bright field and dark field) and fluorescence imaging, and pyrolysis-gas chromatography coupled to mass spectrometry. Microfluidic biosensors and risk assessment assays of MP/NP for in vitro, in vivo, and in silico models have also been used. Advantages and limitations of each method or approach in specific application scenarios are discussed to highlight the scientific and technological obstacles to be overcome in future research. Although progress in recent years has increased our understanding of the mechanisms and the extent to which MP/NP affects health and the environment, many challenges remain largely due to the lack of standardized and reliable detection and characterization methods. Most of the methods available today are low-throughput, which limits their practical application to food and agricultural samples. Development of rapid and high-throughput field-deployable methods for onsite screening of MP/NPs is therefore a high priority. Based on the current literature, we conclude that detecting the presence and understanding the impact of MP/NP throughout the agricultural and food supply chain require the development of novel deployable analytical methods and sensors, the combination of high-precision lab analysis with rapid onsite screening, and a data hub(s) that hosts and curates data for future analysis.

Activities of Microplastics (MPs) in Agricultural Soil: A Review of MPs Pollution from the Perspective of Agricultural Ecosystems

Microplastics are emerging persistent pollutants which have attracted increasing attention worldwide. Although microplastics have been widely detected in aquatic environments, their presence in soil ecosystems remains largely unexplored. Plastic debris accumulates in farmland, causing serious environmental problems, which may directly affect food substances or indirectly affect the members in each trophic level of the food chain. This review summarizes the origins, migration, and fate of microplastics in agricultural soils and discusses the interaction between microplastics and the components in farmland from the perspectives of toxicology and accumulation and deduces impacts on ecosystems by linking the organismal response to an ecological role. The effects on farmland ecosystem function are also discussed, emphasizing the supply of agricultural products, food chain pathways, carbon deposition, and nitrogen cycling and soil and water conservation, as microplastic pollution will affect agricultural ecosystems for a long period, posing an ecological risk. Finally, several directions for future research are proposed, which is important for reducing the effect of microplastics in agricultural systems.

Impact of aquatic microplastics and nanoplastics pollution on ecological systems and sustainable remediation strategies of biodegradation and photodegradation

The extreme degree of microplastics contamination and its negative impact on ecosystems has become a serious and emerging global concern. Microplastics are mainly generated from products that are used primarily in our everyday lives and are also generated from the fragmentation of larger plastic wastes. It easily penetrates the food chain and, when ingested by aquatic animals or humans, can pose serious health problems. Recently, several technologies have been developed to control the unrestricted spread of microplastics and possibly eradicate them; however, still under investigation. In this review, we have illustrated the types of microplastics, their harmful effect on living things, and the progress to degrade them to protect the environment and life on earth. Several promising and eco-friendly technologies including microbial and enzymatic approaches are enticing to eliminate the microplastics. Also, the photodegradation of microplastics contaminations appeals as a more fascinating approach. The metal oxide-assisted photodegradation of microplastics has also been taken into account. This work presented an impact on the comprehensive research for the effective degradation of different microplastic compositions as well as emerging green approaches for a sustainable environment and a healthier life.