Recent advances on ecological effects of microplastics on soil environment

A critical review on the migration, transformation, sampling, analysis and environmental effects of microplastics in the environment

As emerging pollutants, microplastics have recently received considerable attention owing to detection in various organisms and environments. Mass production and widespread use of plastic products increase their potential risks to humans owing to their persistent, mobile, and toxic properties. Numerous methods have been used to identify and quantify the various forms of microplastics, however, unified standards do not exist. In this review, we systematically summarize the sources, migration, transformation, and analytical methods for microplastics in diverse ecosystems, particularly the most recent sampling and identification techniques. Additionally, the environmental effects and health hazards of microplastics on aquatic and terrestrial systems, as well as human beings are discussed. We also present management strategies for reducing microplastics in a broader social and policy context. This review aims to provide an overview of the migration, transformation, sampling, analysis, and environmental effects of microplastics, which addresses knowledge gaps in microplastic pollution and provides proposals for key research gaps.

The silent invasion of microplastics polyvinyl chloride and polyethylene terephthalate: Potential impact on osteoporosis

BACKGROUND

The relationship between the environment and diseases is a crucial and complex topic that has garnered significant attention in recent years. In our study, we also follow the thread and explore the correlation between microplastics (MPs) and osteoporosis (OP).

METHODS AND RESULTS

We found that MPs were detected in the blood samples of nearly all participants. Moreover, It was compelling that PVC and PET emerged as the most common MP polymers in our study. A verification process was conducted comparing the clinical data with the results of MPs detection. This analysis revealed a significant exposure risk to MPs from sources such as bottled water, take-out containers. Through molecular biology techniques, we confirmed that MPs have a significant toxic effect on osteoblasts and associated with abnormal gene expression.

CONCLUSION

MPs may be considered to have a potential correlation with the progression of OP.

Phytoremediation of polyethylene terephthalate (PET) and polypropylene (PP) microplastics by alfalfa (Medicago sativa L.)

Phytoremediation is a plant-based approach for effective biodegradation of environmental pollutants but its efficacy for MPs mainly remains unknown. In this context, in the present study, the biodegradation of polyethylene terephthalate (PET) and polypropylene (PP) microplastics by alfalfa (Medicago sativa L.) was investigated for one year. Treatment with different types and concentrations of MPs showed no significant effects on alfalfa germination rate and growth. Bacterial communities in the rhizosphere of alfalfa with MPs treatment increased significantly compared to untreated controls. Types of MPs showed no effects on bacterial counts. Dehydrogenase (DHO) enzyme activity in the rhizosphere of plants with MPs treatment was significantly higher than plants without MPs treatment but the concentration and types of MPs showed no significant effects on rhizosphere DHO activity. The mean degradation rate for PET-MPs and PP-MPs was 0.29% and 0.44%, respectively. The increase of MPs concentration in the soil from 2 to 10 g/kg elevated the mean degradation rate from 0.26% to 0.48%. Rhizodegradation of MPs is a consequence of complex interactions between MPs, root exudates and microbial activities in the rhizosphere. Therefore, phytoremediation using alfalfa could be considered as a potential method for in situ removal of MPs from the soil.

Organic matter and microplastics nexus: A comprehensive understanding of the synergistic impact on soil health

The interactional nexus of microplastics (MPs) and organic matter (OM) can subtly disrupt the delicate balance of soil ecosystems, influencing nutrient dynamics, biodiversity, and overall soil health. To explore this complex interplay between MPs and OM concerning several perspectives, a comprehensive keyword search was conducted across key scientific databases, and the retrieved data was curated according to the PRISMA guidelines to reflect the objectives. Several studies have highlighted that organic-based inputs, such as manures, composts, and sewage sludge, widely used for soil amendment, are potential sources of MPs to soil contamination. These coinciding sources of MPs and OM raise potential concerns about their impact on overall soil health. MPs and OM have parallel characteristics and play a critical role in the soil organic carbon (SOC) and dissolved organic matter (DOM), critical for biogeochemical transformations and nutrient cycling. In light of this, the present review explores the multifaceted nexus between MPs and OM, explaining their interaction mechanisms and their effects on the biological and physicochemical properties of the soil. Despite significant implications on soil ecosystem, challenges remain in accurately quantifying the effects of MPs due to the complexities introduced by DOM. The intricate interaction between MPs and DOM can obscure analytical results, complicating efforts to separate and identify these pollutants effectively. Given these challenges, this review underscores the urgent need for innovative methods to characterize and quantify MPs in complex environmental matrices. Finally, we discuss emerging research directions aimed at advancing the detection and management of MPs in soil ecosystems.

Impact of land-use patterns on soil microplastics: Distribution characteristics and driving factors in southern China's Pearl River Delta

Land-use type may affect the abundance, polymer types, and distribution characteristics of soil microplastics (MPs), but their distribution remains unknown in the Pearl River Delta region of Guangdong Province. Here, the abundance of MPs in film-mulched soil, farmland, orchard and forest soils was investigated, and characteristics of the MPs (shape, size, color, and polymer composition) were analyzed in soil samples collected from 23 sites. The average abundance of MPs in film-mulched soil, farmland, orchard and forest soil in the southern China were 2981.8, 4179.2, 2393.3 and 1486.7 items kg-1 respectively. Small particles (< 1 mm), fragments and transparent particles were the main characteristics of the MPs observed. The correlation analysis showed that the total abundance of MPs was positively correlated with the precipitation, urbanization level, and soil pH, while negatively correlated with wind speed, indicating their roles in MP deposition and transport. Furthermore, the polymer composition analysis reveals the local sources of MPs and high heterogeneity. These findings emphasize the complex dynamics of MPs are shaped by meteorological factors, anthropogenic activities, and soil properties, which are significant for follow-up studies of MP pollution control and remediation.

Morphological, physiological, and molecular responses of Perilla frutescens to copper stress alleviated by PVC microplastics

Microplastics (MPs) and copper (Cu) are common co-pollutants in agricultural environments, yet their combined effects on plants remain poorly understood. This study investigated the individual and interactive impacts of Cu and polyvinyl chloride (PVC)-MPs on Perilla frutescens, a heavy metal hyperaccumulator and economically important crop, using hydroponic experiments. Low Cu concentrations (<2 mg L-1) promoted growth, whereas higher levels (>2 mg L-1) induced leaf chlorosis, curling, and root decay. PVC-MPs alone exhibited phytotoxicity only at high concentrations (>1000 mg L-1). In combined treatments, 10-100 mg L-1 PVC-MPs alleviated Cu-induced chlorosis and increased leaf area, though higher MP concentrations suppressed root growth. Physiologically, Cu stress impaired photosynthesis, enhanced antioxidant enzyme activity, and increased osmoregulatory substance content. PVC-MPs counteracted these effects by improving photosynthetic efficiency, enhancing peroxidase activity, and reducing osmotic stress markers. Transcriptomic analysis revealed that PVC-MPs upregulated endocytosis-related genes while downregulating jasmonic acid (JA) biosynthesis and lipid metabolism pathways. ABC transporter genes were differentially expressed, functionally linked to these processes. We demonstrate for the first time that PVC-MPs mitigate Cu stress via three synergistic mechanisms: enhanced membrane trafficking (endocytosis activation), suppression of stress-signaling phytohormones (JA), and lipid metabolism reprogramming. These findings redefine MPs' dual role as both pollutants and unexpected alleviators of metal toxicity. While these findings reveal MPs' unexpected capacity to alleviate metal stress, their persistent environmental accumulation necessitates comprehensive risk-benefit analysis and long-term ecological monitoring-highlighting the imperative for science-based evaluation rather than promoting field applications of MPs as stress mitigants.

Spatiotemporal evolution of small microplastics in agricultural soils from long-term pig manure application

Long-term application of organic fertilizers serves as a nutrient source in agriculture, yet the contamination of these materials with small microplastics (sMPs, 20-500 μm) remains poorly understood. Research on the accumulation and morphological transformation of sMPs in soils under extended fertilization regimes is currently scarce. This study employed Laser Direct Infrared (LDIR) Spectroscopy to quantify and characterize sMPs in soils subjected to four fertilization regimes: no fertilizer (CK), pig manure (M), nitrogen-phosphorus-potassium (NPK) fertilizer, and a combination of NPK and pig manure (MNPK). Temporal and spatial dynamics of sMPs were assessed across treatments with prolonged organic input. A progressive increase in both the abundance and type of sMPs was detected in pig manure, reaching 21,376 ± 1008 items kg-1 in 2023-an increase of 180 % compared to 1979.The initial soil sMPs concentrations in 1979 were approximately 3000 items kg-1; after 44 years, levels in M and MNPK treatments reached 7183 ± 568 items kg-1 and 5557 ± 329 items kg-1, respectively. Soils receiving pig manure consistently exhibited higher sMPs concentrations than untreated controls. The relatively elevated levels of sMPs suggest in-situ degradation of larger MPs. Except in the CK treatment, sMPs abundance increased with soil depth. Across all fertilization types, particles within the 30-100 μm range comprised over 46 % of total sMPs, indicating a consistent size distribution. The polymer types and composition in pig manure-amended soils mirrored those identified in the manure itself. These results demonstrate that long-term pig manure application markedly elevates soil sMPs concentrations, increasing the potential for sMPs contamination in agricultural systems.

Enhanced remediation of petroleum in soil by petroleum-degrading bacterium strain TDYN1 and the effects of microplastics

Total petroleum hydrocarbons (TPH) are a kind of widely distributed pollutant, while its bioremediation in situ and how it is affected by microplastics (MPs) in soil remains unknown. A pot experiment was conducted to investigate the degradation capabilities of total petroleum hydrocarbons (TPH) by a novel petroleum hydrocarbon-degrading bacterium TDYN1 with different concentrations of microplastics PP and PE. The TDYN1 significantly enhanced TPH degradation rate at 42.4 ± 0.9%, compared to 12.1 ± 2.6% in the control. The microplastics affected the TPH degradation depended on their amount, and no difference in degradation rates between PP and PE. The 1% PP and PE facilitated the degradation of TPH, while the 4% PP and PE inhibited it after strain added. Strain TDYN1 increased the dehydrogenase, polyphenol oxidase and urease enzyme activities, and the number of TDYN1. After remediation, the pakchoi yield was increased by strain addition, but was reduced by PE, indicating a risk of TPH and PE combined pollution for vegetable growing. It helps to better understand the microbial remediation on TPH-microplastic compound-contaminated soil, and provide theoretical support for its evaluation of application.

Dynamics and Impacts of Microplastics (MPs) and Nanoplastics (NPs) on Ecosystems and Biogeochemical Processes: The Need for Robust Regulatory Frameworks

Microplastics (MPs) and nanoplastics (NPs) pose significant threats to aquatic and terrestrial ecosystems, disrupting nutrient cycling, altering soil properties, and affecting microbial communities. MPs and NPs bioaccumulate and contribute to global nutrient and water cycle disruptions, intensifying the impact of climate change. Despite the widespread use of plastics, inadequate plastic waste management leads to persistent environmental pollution. Toxic compounds are transported by MPs and NPs, affecting food chains, nutrient cycles, and overall ecosystem health. MPs impact soil biogeochemistry, microbial activity, and greenhouse gas emissions by altering the nitrogen and carbon cycles. One of the largest gaps in microplastic (MP) research today is the lack of standardized sampling and analytical methods. This lack of standardization significantly complicates the comparison of results across different studies. Multidisciplinary research and strict regulatory measures are needed to address MP pollution. This review highlights the critical need for mitigation methods to maintain ecosystem integrity and suggests standardization of sampling and data analysis. It offers insights into MP distribution, best practices for data analysis, and the impacts and interactions of MPs with biogeochemical processes. The Environmental Protection Agency has identified a critical need to improve the identification of nanoplastics. Particles smaller than 10 μm become increasingly difficult to quantify using standard MP detection practices.

The spatio-temporal variability of soil microplastic distribution and erosion-induced microplastic export under extreme rainfall event using sediment fingerprinting and 7Be in intensive agricultural catchment

Intensive agricultural production and land management often lead to soil microplastics (MPs) accumulation and aggravated erosion consequently polluting water bodies. However, little is known about the occurrence and migration of soil MPs induced by soil erosion at the catchment scale. This study firstly reported the spatio-temporal variability in soil MPs distribution, and erosion-induced microplastic export loads under extreme rainfall events in an intensive agricultural catchment. The results indicated that microplastic abundance peaked in November 2022 and varied by land use types, among which cropland converted from forest (C(F)) and crop farmland (C) had the highest abundance, vegetable farmland (V) had the lowest abundance on average. Most MPs were < 500 μm and the primary polymers were polyamide (PA), polypropylene (PP) and polyethylene (PE). Sediment contribution and microplastic export loads were identified using compound specific stable isotope and Berillium-7 under an extreme rainfall event. F and C(F) were merged because their δ13C values were non-distinguishable and were identified as the primary sediment source (50.14 ± 0.27 %), contributing most to microplastic export loads due to land management policy shifting. Changed land uses should be the main focus for catchment erosion control and microplastic pollution prevention in intensive agriculture in China and elsewhere.

Synthetic phenolic antioxidant contamination in farmland soils induced by mulching films: Distribution and transformation pathways

The occurrence and distribution of synthetic phenolic antioxidants (SPAs) originating from mulch film in farmland soils, along with their transformation characteristics and pathways, remain largely unknown. This study is the first to investigate nineteen SPAs and four transformation products (TPs) in farmland soils across China. In film-mulching soils, concentrations of SPAs (median, range: 83.6 ng/g, 20.6-863 ng/g) and TPs (46.4 ng/g, 8.36-489 ng/g) were found significantly higher than in nonfilm-mulching soils, suggesting that mulch film is an important SPA source in farmlands. The ecological risk posed by SPAs was considerable, with estimated risk quotients (RQs) reaching up to 14.7. Furthermore, a laboratory soil incubation experiment was conducted on pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionate) (Ir1010), a typical SPA with high estimated ecological risk (RQs up to 3.01). The half-life of Ir1010 in unsterilized soil was 6.73 days, much shorter than in sterilized soils, suggesting that soil microbes effectively promoted its transformation rate. Importantly, ten TPs of Ir1010 were identified in soil through nontargeted screening using high-resolution mass spectrometry, indicating aromatic epoxidation, hydroxylation, and hydrolysis as transformation pathways. This study firstly reveals the occurrence SPAs and TPs in farmland soils and suggests their transformation mechanism, highlighting the complex risks posed by these emerging agricultural contaminants.

Microplastics in groundwater: Environmental fate and possible interactions with coexisting contaminants

Microplastics (MPs) are emerging environmental pollutants which represent a serious threat to ecosystems and human health and have received significant attention from the global community. Currently, a growing number of studies have found the presence of MPs in groundwater. This study exhaustively reviewed varying degrees of recent publications in Web of Science database and investigated the characteristics of MPs (concentration, types, sizes and shapes) in groundwater ecosystems, their migration characteristics, and interactions with co-occurring contaminants. Results suggested that current global research on MPs in groundwater has primarily focused on countries such as India, South Korea, China, Italy and United States. Pollution levels of MPs in groundwater show significant variability, ranging from 0 to 6832 n/L. The predominant plastic polymer types include PP, PE, PS, PA, PET and PVC. The sources of MPs in groundwater are primarily classified as associated with natural processes and anthropogenic activities. The physical, chemical and biological properties can influence the migration of MPs into groundwater. Furthermore, MPs can act as carriers, interacting with co-occurring contaminants, thereby enhancing their migration and toxicity, potentially posing a threat to groundwater ecosystems and human health. Consequently, the major challenges and associated recommendations for forthcoming research on MPs in groundwater are proposed.

Mechanisms for iron oxide nanoparticle alleviation of nanoplastic-induced stress in Perilla frutescens revealed by integrated physiological and transcriptomic analysis

Nanoplastics, infiltrating soil ecosystems through diverse pathways such as agricultural practices, sludge application, and atmospheric deposition, present significant potential risks to global ecological systems. Through adsorption, iron oxide nanoparticles (IONPs) could reduce toxicity and bioavailability of nanoplastics in polluted soil ecosystems. However, little is known about how interactions between IONPs and polystyrene nanoplastics (PSNPs) affect plant growth. This study revealed that iron oxide nanoparticles (IONPs) effectively mitigated the uptake of polystyrene nanoplastics (PSNPs) in Perilla frutescens, demonstrating a substantial reduction of PSNPs accumulation by 46.15% in roots and 24.83% in stems. Furthermore, IONPs application significantly improved plant growth parameters, with notable increases of 20.40% in plant height and 34.22% in biomass compared to plants exposed solely to PSNPs.Compared with PSNPs alone, application of PSNPs + IONPs enhanced plant photosynthetic parameters, reduced the quantity of osmotic substances and reduced the activity of antioxidant enzymes. KEGG analysis was concentrated on photosynthetic metabolism and flavonoid synthesis. Further analysis combined with metabolic pathways revealed that IONPs treatment improved plant growth by up-regulating photosystem genes (PsbP, Psak, and PetC) and flavonoid synthesis genes (CHS, CHI, and F3H). Overall, IONPs enhance Perilla frutescens growth by upregulating photosystem-related genes and mitigate PSNPs-induced oxidative stress through flavonoid biosynthesis pathway activation. The present study provides new insights that will aid development of nano iron fertilizers capable of improving the adverse effects of nano plastics on agricultural production.

Synergy of plastics and heavy metals weakened soil bacterial diversity by regulating microbial functions in the Qinghai-Tibet Plateau

How plastics coupled with metals regulate microbial functions-diversity relationships remain unknown in plateau soil environment. Three representative catchments in the Qinghai-Tibet Plateau, focusing on microplastics, their plasticisers, and metals in soils, were investigated. This research explores responses of bacterial diversity and functions to the co-existence of target pollutants, and pathways by which target pollutants regulate the diversity. Soil bacterial beta diversity and functional genes exhibited negative correlations with phthalate esters across three catchments (p < 0.05). Dibutyl phthalate emerged as a primary factor affecting beta diversity, rather than the quantity of microplastics. Additionally, the synergy of cadmium and fiber-shaped microplastics exacerbated the impact on diversity. Structural equation modeling further elucidated that plastics, copper, and iron influenced nirK/nirS genes and phoD gene, subsequently affected cbbL/cbbM genes, and ultimately the diversity. In this context, microplastics, phthalate esters and copper, iron exerted antagonistic effects on one another. Consequently, the co-existence of plastics and cadmium weakened soil bacterial diversity in the Qinghai-Tibet Plateau by disrupting microbial functions, but micronutrients alleviated these negative impacts. This research reveals that the co-existence of plastics and metals regulates soil bacterial diversity in the Qinghai-Tibet Plateau, providing a valuable reference for the protection of microbial ecology in plateau regions.

Harnessing Electrostatic Forces: A Review of Bees as Bioindicators for Particulate Matter Detection

Bees (Hymenoptera, Anthophila) are widely recognized for their essential ecological roles, including pollination and biodiversity maintenance. Recently, their ability to collect environmental particulate matter through electrostatic forces has been explored for biomonitoring purposes. This review integrates knowledge on electrostatic pollen adhesion with emerging insights into particulate matter adhesion to bees, emphasizing their potential as bioindicators. The mechanisms of electrostatic adhesion, influenced by factors such as the physicochemical properties of particulate matter and bee morphology, are discussed in detail. Additionally, the study evaluates the adhesion efficiency of pollutants, including heavy metals, microplastics, nanoplastics, pathogens, pesticides, radionuclides, and volatile organic compounds. This multidisciplinary approach underscores the role of bees in advancing environmental monitoring methodologies and offers innovative tools for assessing ecosystem health while addressing the drivers of bee decline.

UV-aging reduces the effects of biodegradable microplastics on soil sulfamethoxazole degradation and sul genes development

In recent years, the biodegradable plastics has extensively used in industry, agriculture, and daily life. Herein, the effects of two biodegradable microplastics (BMPs), poly(butyleneadipate-co-terephthalate) (PBAT) and polyhydroxyalkanoate (PHA), on soil sulfamethoxazole (SMX) degradation and sul genes development were comparatively studied based on the type, dosage, and state. The addition of virgin BMPs significantly increased soil DOC following a sequential order PBAT > PHA and high dose > low dose. Meanwhile virgin PBAT significantly reduced soil pH. In general, the addition of BMPs not only promoted soil SMX degradation but also increased the abundance of sul genes, with an exception that pH reduction in virgin PBAT inhibited the proliferation of sul genes. The driving effects of BMPs on soil microbial diversity following the same order as that on DOC. Specific bacteria stimulated by BMPs, such as Arthrobacter and two genera affiliated with phylum TM7, accounted for the accelerated degradation of SMX. Intriguingly, UV-aging hindered the release of DOC from BMPs and the reduction in pH, mitigated the stimulation of microbial communities, and ultimately reduced the promotion effect of BMPs on SMX degradation and sul genes proliferation. Our results suggest that more attention should be paid to the proliferation risk of ARGs in the environment affected by BMPs and UV-aging can be employed sometimes to reduce this risk.

Micro/Nanoplastics in plantation agricultural products: behavior process, phytotoxicity under biotic and abiotic stresses, and controlling strategies

With the extensive utilization of plastic products, microplastics/nanoplastics (MPs/NPs) contamination not only poses a global hazard to the environment, but also induces a new threat to the growth development and nutritional quality of plantation agricultural products. This study thoroughly examines the behavior of MPs/NPs, including their sources, entry routes into plants, phytotoxicity under various biotic and abiotic stresses (e.g., salinity, polycyclic aromatic hydrocarbons, heavy metals, antibiotics, plasticizers, nano oxide, naturally occurring organic macromolecular compounds, invasive plants, Botrytis cinerea mycorrhizal fungi.) and controlling strategies. MPs/NPs in agricultural systems mainly originate from mulch, sewage, compost fertilizer, municipal solid waste, pesticide packaging materials, etc. They enter plants through endocytosis, apoplast pathways, crack-entry modes, and leaf stomata, affecting phenotypic, metabolic, enzymatic, and genetic processes such as seed germination, growth metabolism, photosynthesis, oxidative stress and antioxidant defenses, fruit yield and nutrient quality, cytotoxicity and genotoxicity. MPs/NPs can also interact with other environmental stressors, resulting in synergistic, antagonistic, or neutral effects on phytotoxicity. To address these challenges, this review highlights strategies to mitigate MPs/NPs toxicity, including the development of novel green biodegradable plastics, plant extraction and immobilization, exogenous plant growth regulator interventions, porous nanomaterial modulation, biocatalysis and enzymatic degradation. Finally, the study identifies current limitations and future research directions in this critical field.

Nitrogen Fertilization Alleviates Microplastic Effects on Soil Protist Communities and Rape (Brassica napus L.) Growth

Agricultural plastic mulch enhances crop yields but leads to persistent microplastic contamination in soils. Concurrently, nitrogen (N) fertilization and atmospheric deposition profoundly reshape microbial ecosystems. This study examined the individual and interactive effects of polyethylene microplastics (PE, 1% w/w) and nitrogen addition (N, 180 kg ha-1 yr-1) on soil protist communities and rape (Brassica napus L.) productivity. High-throughput sequencing and soil-plant trait analyses revealed that PE alone reduced the soil water retention and the rape biomass while elevating the soil total carbon content, C/N ratios, and NH₄⁺-N/NO₃--N levels. Conversely, N addition significantly boosted the rape biomass and the chlorophyll content, likely through enhanced nutrient availability. Strikingly, the combined PE_N treatment exhibited antagonistic interactions; protist diversity and functional group composition stabilized to resemble the control conditions, and the rape biomass under the PE_N treatment showed no difference from the CK (with basal fertilizer only), despite significant reductions under the PE treatment alone. Soil nutrient dynamics (e.g., the SWC and the C/N ratio) and the protist community structure collectively explained 96% of the biomass variation. These findings highlight the potential of nitrogen fertilization to mitigate microplastic-induced soil degradation, offering a pragmatic strategy to stabilize crop productivity in contaminated agricultural systems. This study underscores the importance of balancing nutrient management with pollution control to sustain soil health under global microplastic and nitrogen deposition pressures.

Impact of high-density polyethylene (HDPE) microparticles on soil physical-chemical properties, CO2 emissions, and microbial community in a two-year field trial

Contamination by microplastics (MPs) is a serious problem affecting both aquatic and terrestrial ecosystems, but despite the large number of papers published in recent years, the impact of microplastics (MPs) on soil is still debated. This work aims to evaluate the effects of different amounts (0, 1, 2 % v/v) of high-density polyethylene (HDPE) microparticles (1-0.25 mm in size) on soil properties over time. Specifically, in a field plot experiment lasting about 2 years, treated and control soils were periodically sampled and analysed for their physical (aggregate stability and distribution), chemical (total N, soluble C and N, available P), and soil biochemical (basal respiration, microbial biomass C, enzyme activities, and fatty acid methyl ester - EL-FAME) properties. In addition, CO2 fluxes from soil to atmosphere were measured throughout the experiment. The physical and chemical parameters of the treated soils did not differ significantly from the control soil, whereas specific changes occurred in the biochemical characteristics during the experiment, particularly in the soil treated with the higher dose of MPs. In the early period (21 to 46 days after the treatment), some changes in the microbial community structure were observed for the soil treated with 2 % MPs, suggesting the occurrence of stress conditions for the microbial biomass, likely due to nutrient limitation. After 166 g from the start of the experiment, the 2 % MPs-treated soil showed, other than a lower CO2 flux than the control soil, a reduction of basal respiration together with an increase in actinomycetes and total fungi (both saprophytes and AMF). There was also an increase in C-related enzyme activities one year after treatment with MPs. These latter results suggest that the soil microbial community may be adapting to the new conditions and available energy substrates, which may also indicate the onset of HDPE degradation processes.

Chronic Exposure of Adult Zebrafish to Polyethylene and Polyester-based Microplastics: Metabolomic and Gut Microbiome Alterations Reflecting Dysbiosis and Resilience

The study explored the ecotoxicological effects of chronic exposure to microplastic (MP) on adult zebrafish, focusing on environmentally relevant concentrations of polyethylene (PE) beads and polyester (PES). High-throughput untargeted metabolomics via UPLC-QToF-MS and 16S metagenomics for gut microbiota analysis were used to assess ecotoxicity in zebrafish exposed to varying concentrations of PE and PES. The VIP (Variable Importance in Projection) scores indicated PE exposure primarily impacted phospholipids, ceramides, and nucleotide-related compounds, while PES exposure led to alterations in lipid-related compounds, chitin, and amino acid derivatives. From MSEA (Metabolite Set Enrichment Analysis) and Mummichog analyses, PE and PES significantly disrupted key metabolomic pathways associated with inflammation, immune responses, and apoptosis, including leukotriene and arachidonic acid metabolism and the formation of putative anti-inflammatory metabolites from EPA. PE caused physical disruption and inflammation of the epithelial barrier, whereas PES affected gut microbiota interactions, impairing digestion and metabolism. Although alpha diversity within the gut microbiome remained stable, beta diversity analysis revealed significant shifts in microbial composition and structure, suggesting a disruption of functional balance and an increased susceptibility to pathogens. Chronic PE and PES exposures induced shifts in the gut microbial community and interaction network with potential increases in pathogenic bacteria and alteration in commensal bacteria, demonstrating the microbiome's resilience and adaptability to stressors of MPs exposure. High-throughput metabolomics and 16S metagenomics revealed potential chronic diseases associated with inflammation, immune system disorders, metabolic dysfunction, and gut dysbiosis, highlighting the complex relationship between gut microbiome resilience and metabolic disruption under MP-induced stress, with significant ecological implications.

Microplastics and Dechlorane Plus co-exposure amplifies their impacts on soybean plant

The co-existence of microplastics (MPs) and organic pollutants on agricultural ecosystems pose potential implications for both food safety and environmental integrity. The combined effects of MPs with Dechlorane Plus (DP), a newly listed banned flame retardant, remain unknown. This study explores the biological responses of soybean plants to exposure from polyethylene (PE) and polyvinyl chloride (PVC) MPs and DP. Results showed that combined exposure altered the activity of antioxidant enzymes and inhibited the growth of soybean plants, compared with DP or MPs exposure alone. DP markedly reduced both the root length and root weight of soybean plants in a dose-dependent manner. Proteomics profiling suggests that PE interacts with protein translation and modification pathways, particularly via the regulation of heat shock protein binding. High concentration DP (HDP) treatment group enhances the plant's stress resistance by regulating relevant proteins through the modulation of hydrogen peroxide catabolic protein expression and the formation of water channel proteins. In the combined treatments, low concentration DP with PVC triggered increased protein expression related to photosynthesis response, further demonstrating the enhanced inhibitory effects. This study for the first time maps the changes in the physiological and the molecular mechanisms of the impacts on higher plant caused by MPs and DP co-exposure.

Assessment and treatment of microplastics in different environmental compartments of Kallar Kahar Lake-a case study

Microplastic pollution has garnered global attention in recent decades due to its recognized ecological concerns through previous studies. However, in Pakistan, scarce information has been reported on MP pollution concerning the freshwater ecosystem. The current study was conducted on Kallar Kahar Lake, Punjab, Pakistan for (1) quantification, characterization, and distribution of MPs in surface water, sediments, and fish samples and (2) two treatment processes (magnetization and coagulation + flocculation) for the removal of MPs from the water. Samples were collected from each point by grab sampling method to investigate the MPs according to their type, shape, and color. The MP quantification and analysis were accomplished via the counting method by a stereomicroscope and Fourier transform infrared spectroscopy for their polymer type and composition. Results indicated the average MP abundance as 49.6 ± 11.14 MP/500 mL, 143 ± 48.18 MP/100 g, and 79 ± 12.2 items for water, sediments, and fish correspondingly. The dominant MP colors were blue, transparent, and green in all three environmental compartments. The ATR-FTIR identified the polymer types in lake water, sediment, and fish were PPS, PIB, and PLF; PET, PE, PP, and Natural Latex Rubber; and PET, respectively. The MP removal rate was observed high in both treatments. The average % removal rate of iron ore magnetization treatment was observed to be 80% at 1300 mg/L dosage of Fe2O3. Similarly in chemical coagulation processes, the highest MP removal efficiency was 85% (PET), 83% (PPS) and 80% (PIB) at the different concentration dosages of 150 + 15 mg/L, 111 + 15 mg/L, and 150 + 111 + 15 mg/L for Combination 1, Combination 2, and Combination 3, respectively. Overall, this study provided an integrative and novel approach for the removal of MP from surface water, which also holds an explicit commercial utilization prospect to overpower the MP pollution in water bodies. Also, the current findings serve as baseline data for the study of local freshwater systems.

Effects of different microplastics on the physicochemical properties and microbial diversity of rice rhizosphere soil

Biodegradable plastics, as alternatives to conventional waste plastics, are increasingly applied across various fields. However, the ecological risks associated with the widespread use of biodegradable plastics remain unclear. Additionally, biodegradable plastics tend to age in the environment, leading to changes in their physicochemical properties. The ecological risks brought by the aging of microplastics have also been scarcely studied. In this study, we selected conventional microplastics (PE-MPs), biodegradable microplastics (PLA-MPs), and aged biodegradable microplastics (aging-PLA-MPs) to explore their effects on the rhizosphere soil environment of rice. The results showed that microplastics reduced the soil N and P content, with PE slightly increasing the DOC content, while PLA and aging-PLA significantly increased DOC by 21.13 and 24.04%, respectively. Microplastics also decreased soil enzyme activity, with aging-PLA having a somewhat stimulatory effect on enzyme activity compared to PLA. Furthermore, microplastics reduced the soil bacterial diversity index and altered the community structure of dominant bacterial species, with DOC content and FDA hydrolase being the main factors influencing the soil bacterial community. Bacteria were most sensitive to PLA, and the stability of the bacterial microbial network structure decreased, although aging reduced the negative impact of PLA on the bacterial community. This study contributes to our understanding of the ecological risks posed by biodegradable plastics and their aging processes on the environment.

Microplastics in agricultural soil: Unveiling their role in shaping soil properties and driving greenhouse gas emissions

Microplastics (MPs) contamination is pervasive in agricultural soils, significantly influencing carbon and nitrogen biogeochemical cycles and altering greenhouse gas (GHG) fluxes. This review examines the sources, status, mechanisms, and ecological consequences of MPs pollution in agricultural soils, with a focus on how MPs modified soil physicochemical properties and microbial gene expression, ultimately impacting GHG emissions. MPs were found to reduce soil water retention, decreasing soil respiration and increasing emissions of CO2, CH₄, and N2O. They also enhanced soil aggregate stability and influenced soil organic carbon (SOC) sequestration, contributing further to GHG emissions. MPs-induced increases in soil pH were associated with suppressed CH₄ and N2O emissions, whereas the abundance of genes encoding enzymes for cellulose and lignin decomposition (e.g., abfA and mnp) stimulated enzyme activity, intensifying N2O release. Additionally, a reduced soil C/N ratio promoted denitrification processes. Changes in microbial communities, including increases in Actinomycetes and Proteobacteria, were observed, with a rise in genes associated with carbon cycling (abfA, manB, xylA) and nitrification-denitrification (nifH, amoA, nirS, nirK), further exacerbating CO2 and N2O emissions. This review provides valuable insights into the complex roles of MPs in GHG dynamics in agricultural soils, offering perspectives for improving environmental management strategies.

The threat of microplastics and microbial degradation potential; a current perspective

Microplastics in marine environments come from various sources, and over the years, their buildup in marine environments suggests an inevitable need for the safe mitigation of plastic pollution. Microplastics are one of the chief and hazardous components of marine pollution, as they are transferred through the food chain to different trophic levels, affecting living organisms. They are also a source of transfer for pathogenic organisms. Upon transfer to humans, several toxic effects can occur. This review aims to assess the accumulation of microplastics in marine environments globally, the threat posed to humans, and the biodegradation potential of bacteria and fungi for future mitigation strategies. The versatility of bacteria and fungi in the biodegradation of different types of plastics has been discussed, with a focus on the microbial majority that has been cultivated in labs from the marine environment. We also propose that the exploration of yet-to-be-cultivated microbial majority can be a way forward for employing future strategies to mitigate microplastics.

The effect of polyvinyl chloride microplastics on soil properties, greenhouse gas emission, and element cycling-related genes: Roles of soil bacterial communities and correlation analysis

Different shapes (membranes and particles) and concentrations (1 % (w/w) and 2 % (w/w)) of polyvinyl chloride (PVC) microplastics (MPs) were investigated to determine their impact on the soil environment. The incorporation of MPs can disrupt soil macroaggregates. Compared with 1 % (w/w) MPs, 2 % MPs resulted in a significant increase in soil organic carbon content. MP particles significantly increased soil CO2 emissions, and CH4 emissions were enhanced by both membrane and particle MPs at high concentrations. Microplastics can alter the abundance of Actinobacteria, Proteobacteria, Chloroflexi, Acidobacteriota, and Firmicutes at the phylum level, and Nocardioides, Rhodococcus and Bacillus at the genus level. MP particles had a more significant impact on soil bacterial communities than MP membranes. The relative abundances of genes involved in the C, N, and P cycles were detected by qPCR, and more remarkable changes were observed in MP membrane treatments. The relative abundance of Vicinamibacteraceae and Vicinamibacterales exhibited a positive correlation with most C/N/P cycle-related genes, whereas Pseudarthrobacter and Nocardioides demonstrated a negative correlation. This study highlights that the influence of MPs on soil parameters is mediated by soil microorganisms, providing insight into the effects of MPs on the soil microenvironment.

Antibiotic resistance genes transfer risk: Contributions from soil erosion and sedimentation activities, agricultural cycles, and soil chemical contamination

The transfer of antibiotic resistance genes (ARGs) pose environmental risks that are influenced by soil activity and pollution. Soil erosion and sedimentation accelerate degradation and migration, thereby affecting soil distribution and contamination. This study quantified the vertical and horizontal transfer capabilities of ARGs and simulated soil environments under various scenarios, such as erosion, agricultural cycles, and chemical pollution. The results showed that slope, runoff, and sediment volume significantly affected soil erosion and ARG transfer risks. The response of environmental factors to the transfer risk of ARGs is as follows: the promotion effect of soil deposition (average: 21.41 %) is significantly greater than the inhibitory effect of soil erosion (average: -11.31 %); the planting period (average: -64.654) is greater than the harvest period (average: -56.225); the response to soil chemical pollution is: the impact of phosphate fertilizer residues, antibiotics, and pesticide pollution is more significant. This study constructed a vertical and horizontal transfer system of ARGs in soil erosion and sedimentation environments and proposed a response analysis method for the impact of factors, such as soil erosion and sedimentation activities, agricultural cycles, and soil chemical pollution, on ARGs transfer capabilities.

Existence and fate of microplastics in terrestrial environment: A global fretfulness and abatement strategies

Widespread use of plastics in consumer products, packaging, cosmetics, and industrial and agricultural production has resulted in the ubiquitous occurrence of microplastics in terrestrial environment. Compared to the marine environment, only limited studies have investigated the microplastics pollution and associated risk in terrestrial environment. The present review summarizes the global distribution of microplastics in terrestrial environment, their transport pathways and fate, risk to ecosystem and human health, and abatement strategies. Small particle sizes (<500 μm); fragment, fiber, and film shapes; transparent and white color; polyethylene (PE), polypropylene (PP), and polyethylene terephthalate (PET) polymers were the major characteristics of the microplastics found in terrestrial environment. Microplastics in soils negatively affect soil organisms, while the impact of microplastics in terrestrial environment on human health is poorly understood, which needs to be explored further as there is clear evidence on their presence in human bodies. The removal of microplastics from soil environment is quite complex and costly, thus prevention of their releases is preferable. Among the existing abatement options, biodegradation, which harnesses bacterial strains to degrade microplastics through enzymatic hydrolysis, hold promise for terrestrial environment. Strengthening global cooperation, implementing timely policies on plastic use and recycle, and developing new technologies for control of microplastics are recommended to reduce the pollution in terrestrial environment. Global effort on reducing plastic wastes and enhancing their management is imperative, while substitution with biodegradable plastics could help minimize future accumulation of microplastics in terrestrial environment.

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.

Global microplastics pollution: a bibliometric analysis and review on research trends and hotspots in agroecosystems

The prevalence of microplastics (MPs) in agricultural ecosystems poses a notable threat to dynamics of soil ecosystems, crop productivity, and global food security. MPs enter agricultural ecosystems from various sources and have considerable impacts on the physiochemical properties soil, soil organisms and microbial communities, and plants. However, the intensity of these impacts can vary with the size, shape, types, and the concentrations of MPs in the soil. Besides, MPs can enter food chain through consummation of crops grown on MPs polluted soils. In this study, we conducted a bibliometric analysis of 1636 publications on the effects of MPs on agricultural ecosystems from 2012 to May 2024. The results revealed a substantial increase in publications over the years, and China, the USA, Germany, and India have emerged as leading countries in this field of research. Social network analysis identified emerging trends and research hotspots. The latest burst keywords were contaminants, biochar, polyethylene microplastics, biodegradable microplastics, antibiotic resistance genes, and quantification. Furthermore, we have summarized the effects of MPs on various components of agricultural ecosystems. By integrating findings from diverse disciplinary perspectives, this study provides a valuable insight into the current knowledge landscape, identifies research gaps, and proposes future research directions to effectively tackle the intricate challenges associated with MPs pollution in agricultural environments.

Microplastics and nanoplastics in soil: Sources, impacts, and solutions for soil health and environmental sustainability

The present review discusses the growing concern of microplastics (MPs) and nanoplastics (NPs) in soil, together with their sources, concentration, distribution, and impact on soil microorganisms, human health, and ecosystems. MPs and NPs can enter the soil through various pathways, such as agricultural activities, sewage sludge application, and atmospheric deposition. Once in the soil, they can accumulate in the upper layers and affect soil structure, water retention, and nutrient availability. The presence of MPs and NPs in soil can also have ecological consequences, acting as carriers for pollutants and contaminants, such as heavy metals and persistent organic pollutants. Additionally, the leaching of chemicals and additives from MPs and NPs can pose public health risks through the food web and groundwater contamination. The detection and analyses of MPs and NPs in soil can be challenging, and methods involve spectroscopic and microscopy techniques, such as Fourier-transform infrared spectroscopy and scanning electron microscopy. To mitigate the presence and effects of MPs and NPs in soil, it is essential to reduce plastic waste production, improve waste management practices, and adopt sustainable agricultural practices. Effective mitigation measures include implementing stricter regulations on plastic use, promoting biodegradable alternatives, and enhancing recycling infrastructure. Additionally, soil amendments, such as biochar and compost, can help immobilize MPs and NPs, reducing their mobility and bioavailability. This review article aims to provide a comprehensive understanding of these emerging environmental issues and identify potential solutions to alleviate their impact on soil health, ecosystem functioning, and community health.

Microplastics exacerbate tissue damage and promote carcinogenesis following liver infection in mice

Cancer is a leading cause of death worldwide, posing a substantial threat to human well-being. Microplastics (MPs) exposure can harm human health and the carcinogenicity of MP remains uncertain. In this study, we investigated carcinogenesis by MPs exposure. We observed MP significantly exacerbated hepatic injury in infectious conditions. In addition, cancer-related p53 and p21 signals are activated by MPs. Analysis of the liver transcriptomic landscape uncovered a noteworthy intensification of the carcinogenesis pathway by MPs compared with pre-infection. The transcription factor SALL2 could act as an oncogenic promoter in the promotion of cancer regulated by MPs. Further, big data analysis presents the correlation between MPs pollution and human hepatocellular carcinoma. This work revealed a toxic amplification effect of the non-bioactive MPs on the bioactive pathogens. This finding provides new insight into understanding the potential toxicity of the MPs.

Nonbiodegradable microplastic types determine the diversity and structure of soil microbial communities: A meta-analysis

As an emerging contaminant, microplastics (MPs) have received considerable attention for their potential threat to the soil environment. However, the response of soil bacterial and fungal communities to MPs exposure remains unclear. In this study, we conducted a global meta-analysis of 95 publications and 2317 observations to assess the effects of nonbiodegradable MP properties and exposure conditions on soil microbial biomass, alpha and beta diversity, and community structure. Our results indicate that MPs increased (p < 0.05) soil active microbial biomass by 42%, with the effect varying with MPs type, exposure concentration, exposure time and soil pH. MPs concentration was identified as the most important factor controlling the response of soil microbial biomass to MPs. MPs addition decreased (p < 0.05) the soil bacterial Shannon and Chao1 indices by 2% and 3%, respectively, but had limited effects (p > 0.05) on soil fungal Shannon and Chao1 indices. The type of MPs and exposure time determined the effects of MPs on bacterial Shannon and Chao1 indices, while the type of MPs and soil pH controlled the response ratios of fungal Shannon and Chao1 indices to MPs. Specifically, soil organic carbon (SOC) was the major factor regulating the response ratio of bacterial alpha diversity index to MPs. The presence of MPs did not affect soil bacterial community structure and beta diversity. Our results highlight that MPs reduced bacterial diversity and richness but increased the soil active microbial biomass, suggesting that MPs could disrupt biogeochemical cycles by promoting the growth of specific microorganisms.

Distinct impacts of microplastics on the carbon sequestration capacity of coastal blue carbon ecosystems: A case of seagrass beds

Seagrass beds, as an important coastal blue carbon ecosystem, are excellent at storing organic carbon and mitigating the impacts of global climate change. However, seagrass beds are under threat due to increased human activities and ubiquitous presence of microplastics (MPs) in marine environments. Bibliometric analysis shows that the distribution and accumulation of microplastics in seagrass beds has been widely documented worldwide, but their impacts on seagrass beds, particularly on carbon sequestration capacity, have not been given sufficient attention. This review aims to outline the potential impacts of MPs on the carbon sequestration capacity of seagrass ecosystems across five key aspects: (1) MPs act as sources of organic carbon, contributing to direct pollution in seagrass ecosystems; (2) Impacts of MPs on seagrasses and their epiphytic algae, affecting plant growth and net primary productivity; (3) Impacts of MPs on microorganisms, influencing production of recalcitrant dissolved organic carbon and greenhouse gas; (4) Impacts of MPs on seagrass sediments, altering the quality, structure, properties and decomposition processes of plant litters; (5) Other complex impacts on the seagrass ecosystems, depending on different behaviors of MPs. Latest progress in these fields are summarized and recommendations for future work are discussed. This review can provide valuable insights to facilitate future multidisciplinary investigations and encourage society-wide implementation of effective conservation measures to enhance the carbon sequestration capacity of seagrass beds.

Microplastics from face masks: Unraveling combined toxicity with environmental hazards and their impacts on food safety

Microplastics (MPs) refer to tiny plastic particles, typically smaller than 5 mm in size. Due to increased mask usage during COVID-19, improper disposal has led to masks entering the environment and releasing MPs into the surroundings. MPs can absorb environmental hazards and transfer them to humans and animals via the food chain, yet their impacts on food safety and human health are largely neglected. This review summarizes the release process of MPs from face masks, influencing factors, and impacts on food safety. Highlights are given to the prevalence of MPs and their combined toxicities with other environmental hazards. Control strategies are also explored. The release of MPs from face masks is affected by environmental factors like pH, UV light, temperature, ionic strength, and weathering. Due to the chemical active surface and large surface area, MPs can act as vectors for heavy metals, toxins, pesticides, antibiotics and antibiotic resistance genes, and foodborne pathogens through different mechanisms, such as electrostatic interaction, precipitation, and bioaccumulation. After being adsorbed by MPs, the toxicity of these environmental hazards, such as oxidative stress, cell apoptosis, and disruption of metabolic energy levels, can be magnified. However, there is a lack of comprehensive research on both the combined toxicities of MPs and environmental hazards, as well as their corresponding control strategies. Future research should prioritize understanding the interaction of MPs with other hazards in the food chain, their combined toxicity, and integrating MPs detection and degradation methods with other hazards.

Global perspective of ecological risk of plastic pollution on soil microbial communities

Introduction

The impacts of plastic pollution on soil ecosystems have emerged as a significant global environmental concern. The progress in understanding how plastic pollution affects soil microbial communities and ecological functions is essential for addressing this issue effectively.

Methods

A bibliometric analysis was conducted on the literature from the Web of Science Core Collection database to offer valuable insights into the dynamics and trends in this field.

Results

To date, the effects of plastic residues on soil enzymatic activities, microbial biomass, respiration rate, community diversity and functions have been examined, whereas the effects of plastic pollution on soil microbes are still controversial.

Discussion

To include a comprehensive examination of the combined effects of plastic residue properties (Type, element composition, size and age), soil properties (soil texture, pH) at environmentally relevant concentrations with various exposure durations under field conditions in future studies is crucial for a holistic understanding of the impact of plastic pollution on soil ecosystems. Risk assessment of plastic pollution, particularly for nanoplasctics, from the perspective of soil food web and ecosystem multifunctioning is also needed. By addressing critical knowledge gaps, scholars can play a pivotal role in developing strategies to mitigate the ecological risks posed by plastic pollution on soil microorganisms.

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.

Investigating the impact of microplastics on triphenyl phosphate adsorption in soil: Insights into environmental factors and soil properties

Microplastics (MPs) pose significant environmental pollution problems owing to their diverse properties such as various shapes, sizes, compositions, surface features, and levels of degradation. Moreover, their interactions with toxic chemicals and aging processes add complexity to environmental research. This study investigated the adsorption of triphenyl phosphate (TPhP) in soil-only, MP-only, and soil-MP simulated environments under different conditions. The experiment involved three phases: initial exposure to a pH of 5.5 under fluorescent light, subsequent introduction of ultraviolet (UV) radiation, and pH adjustment to 4.0 and 7.0, while maintaining UV exposure, each lasting 7 days. The study found that environmental factors affected TPhP sorption capacity, with higher adsorption observed under UV radiation and acidic conditions. In contrast, the MP-only systems showed no clear trend for TPhP adsorption, suggesting kinetic limitations. When MPs were added to the soil, the adsorption dynamics were altered, with varying adsorption capacities observed for different MP polymers under different aging conditions. ATR-FTIR spectroscopy, micro-Raman spectroscopy, and water contact angle measurements suggested potential photooxidation processes and changes in the surface hydrophobicity of the MPs subjected to simulated environmental conditions. This study provides valuable insights into the interplay between soil properties, MP characteristics, and environmental factors in determining TPhP sorption dynamics in soil-MP environments.

Perspectives on the Toxic Effects of Micro- and Nanoplastics on the Environment: A Bibliometric Analysis of the 2014 to 2023 Period

Over the past decade, micro- and nanoplastics (MNPs) have garnered significant attention due to their frequent detection in and potential toxic effects on the environment and organisms, making them a serious threat to human health. To comprehensively understand the research on MNPs' toxicity, we employed the R language-based Bibliometrix toolkit (version 4.3.0), VOSviewer (version 1.6.11) and CiteSpace (version 6.3.R1) to perform statistical and visual analyses of 3541 articles pertaining to MNPs' toxicity between 2014 and 2023, which were retrieved from the Web of Science Core Collection (WOSCC) database. The analysis revealed that research related to MNPs' toxicity has experienced a rapid increase in recent years. China's particularly prominent influence in the field of MNPs' toxicity is evidenced by its academic exchanges and the establishment of a mature cooperation system with other countries (regions), such as the USA and Germany. Studies related to MNPs' toxicity are primarily published in leading journals, including the Science of the Total Environment, Environmental Pollution, and the Journal of Hazardous Materials. The Chinese Academy of Sciences was identified as the leading institution in terms of research on MNPs' toxicity, contributing 203 papers to the total number of studies published. Keyword co-occurrence and burst analyses indicated that the current research on MNPs' toxicity mainly focuses on the toxic effects of MNPs on aquatic organisms, the combined toxicity of MNPs and other contaminants, and the toxic effects and mechanisms of MNPs. Future research should integrate computational toxicology and toxicomics to enhance our understanding of MNPs' toxicity mechanisms and assess the potential health risks posed by atmospheric MNPs.

PM10-bound microplastics and trace metals: A public health insight from the Korean subway and indoor environments

Inhalable airborne microplastics (MPs) presented in indoor and outdoor environments, can deeply penetrate the lungs, potentially triggering inflammation and respiratory illnesses. The present study aims to evaluate human health risks from respirable particulate matter (PM)-bound trace metals and MPs in indoor (SW- subway and IRH- indoor residential houses) and outdoor (OD) environments. This research provides an initial approach to human respiratory tract (HRT) mass depositions of PM10-bound total MPs and nine specific MP types to predict potential human health threats from inhalation exposure. Results indicate that PM-bound trace metals and MPs were around 4 times higher in SW microenvironments compared to OD locations. In IRH, cancer risk (CR) levels were estimated 9 and 4 times higher for PM10 and PM2.5, respectively. Additionally, MP particle depositions per gram of lung cell weight were highest in IRH (23.77), followed by OD and SW. Whereas, lifetime alveoli depositions of MPs were estimated at 13.73 MP/g, which exceeds previously reported respiratory disease fatality cases by 10 to 5 times. Prolonged exposure duration at IRH emerged as a key factor contributing to increased CR and MP lung deposition levels. This research highlights severe lung risks from inhaling PM-bound MPs and metals, offering valuable health insights.

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.

Small-size polyethylene and polylactic microplastic alterations on soil aggregate formation with soil sterilization

Soil microplastic contamination is emerging as a significant environmental concern affecting soil properties and biota, including soil aggregation. This study aimed to determine the influence of soil microplastics on soil aggregation, their impact through effects on soil microorganisms, and their effects on water and mechanical stability of soil aggregates. Soil incubation experiments were conducted using sterilized and non-sterilized soils with 15-μm polyethylene and polylactic microplastics over one month. Sterilized soils showed more water-stable aggregates, particularly in the 0.25-0.5 mm fraction (+49%), with both polyethylene and polylactic MPs significantly increasing this fraction (+34% and +35%, respectively). However, no significant effects of soil sterilization and MP addition were found on mechanical stability. The addition of MPs tended to decrease aggregate surface roughness but not significantly (-17～21%). The study provides insights into the complex interactions between microplastics and soil aggregation, suggesting that MP effects may not necessarily be related to their toxicity on soil microbes but could involve various physical interactions.

Photoaged nanoplastics with multienzyme-like activities significantly shape the horizontal transfer of antibiotic resistance genes

Nanoplastics (NPs), identified as emerging pollutants, pose a great risk to environment and global public health, exerting profound influences on the prevalence and dissemination of antibiotic resistance genes (ARGs). Despite evidence suggesting that nano-sized plastic particles can facilitate the horizontal gene transfer (HGT) of ARGs, it is imperative to explore strategies for inhibiting the transfer of ARGs. Currently, limited information exists regarding the characteristics of environmentally aged NPs and their impact on ARGs propagation. Herein, we investigated the impact of photo-aged NPs on the transfer of ARG-carrying plasmids into Escherichia coli (E. coli) cells. Following simulated sunlight irradiation, photo-aged nano-sized polystyrene plastics (PS NPs) exhibited multiple enzyme-like activities, including peroxidase (POD) and oxidase (OXD), leading to a burst of reactive oxygen species (ROS). At relatively low concentrations (0.1, 1 μg/mL), both pristine and aged PS NPs facilitated the transfer of pUC19 and pHSG396 plasmids within E. coli due to moderate ROS production and enhanced cell membrane permeability. Intriguingly, at relatively high concentrations (5, 10 μg/mL), aged PS NPs significantly suppressed plasmids transformation. The non-unidirectional impact of aged PS NPs involved the overproduction of ROS (•OH and •O2-) via nanozyme activity, directly degrading ARGs and damaging plasmid structure. Additionally, oxidative damage to bacteria resulted from the presence of much toxic free radicals, causing physical damage to cell membranes, reduction of the SOS response and restriction of adenosine-triphosphate (ATP) supply, ultimately leading to inactivation of recipient cells. This study unveils the intrinsic multienzyme-like activity of environmentally aged NPs, highlighting their potential to impede the transfer and dissemination of ARGs.

Decoding the molecular concerto: Toxicotranscriptomic evaluation of microplastic and nanoplastic impacts on aquatic organisms

The pervasive and steadily increasing presence of microplastics/nanoplastics (MPs/NPs) in aquatic environments has raised significant concerns regarding their potential adverse effects on aquatic organisms and their integration into trophic dynamics. This emerging issue has garnered the attention of (eco)toxicologists, promoting the utilization of toxicotranscriptomics to unravel the responses of aquatic organisms not only to MPs/NPs but also to a wide spectrum of environmental pollutants. This review aims to systematically explore the broad repertoire of predicted molecular responses by aquatic organisms, providing valuable intuitions into complex interactions between plastic pollutants and aquatic biota. By synthesizing the latest literature, present analysis sheds light on transcriptomic signatures like gene expression, interconnected pathways and overall molecular mechanisms influenced by various plasticizers. Harmful effects of these contaminants on key genes/protein transcripts associated with crucial pathways lead to abnormal immune response, metabolic response, neural response, apoptosis and DNA damage, growth, development, reproductive abnormalities, detoxification, and oxidative stress in aquatic organisms. However, unique challenge lies in enhancing the fingerprint of MPs/NPs, presenting complicated enigma that requires decoding their specific impact at molecular levels. The exploration endeavors, not only to consolidate existing knowledge, but also to identify critical gaps in understanding, push forward the frontiers of knowledge about transcriptomic signatures of plastic contaminants. Moreover, this appraisal emphasizes the imperative to monitor and mitigate the contamination of commercially important aquatic species by MPs/NPs, highlighting the pivotal role that regulatory frameworks must play in protecting all aquatic ecosystems. This commitment aligns with the broader goal of ensuring the sustainability of aquatic resources and the resilience of ecosystems facing the growing threat of plastic pollutants.

Ecological effect of microplastics on soil microbe-driven carbon circulation and greenhouse gas emission: A review

Soil organic carbon (SOC) pool, the largest part of terrestrial ecosystem, controls global terrestrial carbon balance and consequently presented carbon cycle-climate feedback in climate projections. Microplastics, (MPs, <5 mm) as common pollutants in soil ecosystems, have an obvious impact on soil-borne carbon circulation by affecting soil microbial processes, which play a central role in regulating SOC conversion. In this review, we initially presented the sources, properties and ecological risks of MPs in soil ecosystem, and then the differentiated effects of MPs on the component of SOC, including dissolved organic carbon, soil microbial biomass carbon and easily oxidized organic carbon varying with the types and concentrations of MPs, the soil types, etc. As research turns into a broader perspective, greenhouse gas emissions dominated by the mineralization of SOC coming into view since it can be significantly affected by MPs and is closely associated with soil microbial respiration. The pathways of MPs impacting soil microbes-driven carbon conversion include changing microbial community structure and composition, the functional enzyme's activity and the abundance and expression of functional genes. However, numerous uncertainties still exist regarding the microbial mechanisms in the deeper biochemical process. More comprehensive studies are necessary to explore the affected footprint and provide guidance for finding the evaluation criterion of MPs affecting climate change.

Microplastics in Ghana: An in-depth review of research, environmental threats, sources, and impacts on ecosystems and human health

Microplastics pose significant challenges on a global scale. In Ghana, these tiny pollutants infiltrate diverse ecosystems such as coastal areas, rivers, lakes, and forests, vital to the nation's economy and social well-being. This review examines the current depth of knowledge in research and the escalating concern of microplastics, identifying significant gaps in research and understanding. The findings highlight the limited understanding of the extent and distribution of microplastic pollution across different environmental compartments, primarily focusing on coastal environments. Additionally, detection and quantification techniques for microplastics face several complexities and limitations in the Ghanaian context due to constraints such as infrastructure, resources, and expertise. Despite some research efforts, particularly along the coastline, there is still a distinct lack of attention in various regions and ecosystems within Ghana. This imbalance in research focus hinders the understanding and effective mitigation of microplastics in the country. This therefore necessitates the implementation of systematic policy frameworks, emphasizing the importance of recycling and upcycling as effective strategies to address the challenges of microplastics in Ghana with more targeted research and public engagement. This review serves as a call to action for a strategic approach to research and policy-making on microplastic research and pollution in Ghana.

Microplastics as carriers of antibiotic resistance genes and pathogens in municipal solid waste (MSW) landfill leachate and soil: a review

Landfill leachate contains antibiotic resistance genes (ARGs) and microplastics (MPs), making it an important reservoir. However, little research has been conducted on how ARGs are enriched on MPs and how the presence of MPs affects pathogens and ARGs in leachates and soil. MPs possess the capacity to establish unique bacterial populations and assimilate contaminants from their immediate surroundings, generating a potential environment conducive to the growth of disease-causing microorganisms and antibiotic resistance genes (ARGs), thereby exerting selection pressure. Through a comprehensive analysis of scientific literature, we have carried out a practical assessment of this topic. The gathering of pollutants and the formation of dense bacterial communities on microplastics create advantageous circumstances for an increased frequency of ARG transfer and evolution. Additional investigations are necessary to acquire a more profound comprehension of how pathogens and ARGs are enriched, transported, and transferred on microplastics. This research is essential for evaluating the health risks associated with human exposure to these pollutants.

Graphical Abstract

Insights into the influence of polystyrene microplastics on the bio-degradation behavior of tetrabromobisphenol A in soil

Soil contamination by emerging pollutants tetrabromobisphenol A (TBBPA) and microplastics has become a global environmental issue in recent years. However, little is known about the effect of microplastics on degradation of TBBPA in soil, especially aged microplastics. In this study, the effect of aged polystyrene (PS) microplastics on the degradation of TBBPA in soil and the mechanisms were investigated. The results suggested that the aged microplastics exhibited a stronger inhibitory effect on the degradation of TBBPA in soil than the pristine microplastics, and the degradation efficiency of TBBPA decreased by 21.57% at the aged microplastic content of 1%. This might be related to the higher TBBPA adsorption capacity of aged microplastics compared to pristine microplastics. Aged microplastics strongly altered TBBPA-contaminated soil properties, reduced oxidoreductase activity and affected microbial community composition. The decrease in soil oxidoreductase activity and relative abundance of functional microorganisms (e.g., Bacillus, Pseudarthrobacter and Sphingomonas) caused by aged microplastics interfered with metabolic pathways of TBBPA. This study indicated the importance the risk assessment and soil remediation for TBBPA-contaminated soil with aged microplastics.

Humic substance mitigated the microplastic-induced inhibition of hydroxyl radical production in riparian sediment

Hydroxyl radicals (·OH) generated during the flooding-drought transformation process play a vital role in affecting nutrient cycles at riparian zone. However, information on the processes and mechanisms for ·OH formation under the influence of microplastics (MPs) remains unclear. In this study, the effects of MPs on ·OH production from riparian sediments with different biomass [e.g., vegetation lush (VL) and vegetation barren (VB)] were studied. The results showed that presence of MPs inhibited the production of ·OH by 27 % and 7.5 % for VB and VL sediments, respectively. The inhibition was mainly resulted from the MP-induced reduction of the biotic and abiotic mediated Fe redox processes. Spectral analysis revealed that VL sediments contained more high-molecular-weight humic-like substances. Presence of MPs increased the abundances and activities of Proteobacteria, Acidobacteria and Actinobacteria, which were conducive to the changes in humification and polar properties of organic matters. The reduced humic- and fulvic-like substances were accumulated in the flooding period and substantially oxidized during flooding/drought transformation due to the enhanced MP-mediated electron transfer abilities, thus mitigated the MP-induced inhibition effects. Therefore, in order to better understanding the biogeochemical cycling of contaminants as influenced by ·OH and MPs in river ecosystems, humic substances should be considered systematically.

Enhanced biotoxicity by co-exposure of aged polystyrene and ciprofloxacin: the adsorption and its influence factors

Microplastics (MPs), as emerging contaminants, usually experience aging processes in natural environments and further affect their interactions with coexisted contaminants, resulting in unpredictable ecological risks. Herein, the effect of MPs aging on their adsorption for coexisting antibiotics and their joint biotoxicity have been investigated. Results showed that the adsorption capacity of aged polystyrene (PS, 100 d and 50 d) for ciprofloxacin (CIP) was 1.10-4.09 times higher than virgin PS due to the larger BET surface area and increased oxygen-containing functional groups of aged PS. Following the increased adsorption capacity of aged PS, the joint toxicity of aged PS and CIP to Shewanella Oneidensis MR-1 (MR-1) was 1.03-1.34 times higher than virgin PS and CIP. Combined with the adsorption process, CIP posed higher toxicity to MR-1 compared to aged PS due to the rapid adsorption of aged PS for CIP in the first 12 h. After that, the adsorption process tended to be gentle and hence the joint toxicity to MR-1 was gradually dominated by aged PS. A similar transformation between the adsorption rate and the joint toxicity of PS and CIP was observed under different conditions. This study supplied a novel perception of the synergistic effects of PS aging and CIP on ecological health.