Abstract:【Objective】Microplastics and herbicides are ubiquitous contaminants in agricultural soils; however, their combined impact on soil carbon cycling and dissolved organic matter (DOM) remains underexplored.【Method】In this study, polylactic acid (PLA) microplastics and fomesafen were used as model contaminants to investigate their effects on soil carbon dioxide (CO2) emission and characteristics of DOM through soil incubation experiments as well as ultraviolet/fluorescence spectroscopy techniques.【Result】The results revealed that both PLA microplastics and fomesafen enhanced the CO2 emission rates in Mollisols and red soil during the 7–45 day incubation period. However, by the 60th day, individual treatment of fomesafen reduced the CO2 emission rate in red soil by 14.8% to 21.6%. Notably, the combined presence of fomesafen and PLA microplastics exhibited a synergistic effect, further suppressing the CO2 emission rate in red soil by 54.3% to 79.7%. The addition of 0.1% and 1% PLA microplastics increased the DOM content in both soil types. Ultraviolet/fluorescence spectroscopy analyses indicated that PLA microplastics enhanced the DOM humification and aromaticity of Mollisols. Also, the high level of combined contamination accelerated the transformation of organic matter in red soil. PARAFAC analysis identified three fluorescent components: terrestrial humic-like, short-wave humic, and fulvic acid-like substances. Polylactic acid microplastics significantly increased the content of these components in Mollisols, whereas the combined contamination did not markedly alter the DOM composition in red soil.【Conclusion】This study provides critical scientific data and insights into the effects of microplastics and herbicides on soil carbon cycling, contributing to a deeper understanding of soil ecological health and informing management strategies.

Abstract:【Objective】The ecotoxicity of microplastics (MPs) to soil fauna is widely recognized. However, the degree of MP aging under different exposure durations, their differential toxic effects on soil fauna, and the dynamics of toxicity changes remain poorly understood.【Methods】In our study, microcosm experiments were conducted to compare both the aging degree of polyethylene (PE-MP) and polylactic acid microplastics (PLA-MP) exposed for 30/60 days and their ecotoxicities to earthworms. 【Result】The characteristic peak intensity of both aged PE-MP and PLA-MP exhibited significant alterations at 717 cm?1 and within the 1000-1257 cm?1 range. The carbonyl index (CI) of PE-MP and PLA-MP increased from 0.26 to 0.72 and 3.23 to 3.35, respectively. Also, scanning electron microscopy (SEM) demonstrated visible surface cracks and fractures, confirming aging on both MPs. Aging significantly enhanced the toxicity of MP on earthworms and the redox balance of earthworms was disrupted when exposed to both PE-MP and PLA-MP. This was associated with fluctuations in reactive oxygen species (ROS) and oxidative stress. After 60 days of exposure, the concentration of malondialdehyde (MDA) increased by 36.22% and 11.47%, while glutathione-S-transferase (GST) increased by 107.32% and 33.44% in PE-MP and PLA-MP treatments, respectively. In addition, the activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) decreased by 27.07% & 30.62%, 24.78% & 55.51%, and 52.90% & 47.78%, respectively. SEM and histopathological analyses revealed more severe damage to the epidermis and intestinal tissues in PLA-MP-exposed earthworms than those of PE-MP. Intestinal MP bioaccumulation significantly increased from 2.50±0.28 μg·mg–1 to 6.17±0.13 μg·mg–1 with prolonged exposure, ultimately causing irreversible physiological impairment. 【Conclusion】The aging of PE-MP and PLA-MP in soil induced significant physiological damage and oxidative stress in Eisenia fetida. Notably, PLA-MP shows greater susceptibility to aging and induces stronger physiological toxicity compared to PE-MP.

Abstract:Microplastics in soils pose potential threats to human health and food security, and the attention to this issue is increasing. However, there is still no clear and unified conclusion on the current status of soil microplastic pollution, as well as corresponding governance measures. Clarifying the current status of soil microplastic pollution is of great significance for its effective management. This article provides an in-depth exposition on the concept and development of microplastics, summarizes the pollution characteristics, sources, and ecological environmental effects of soil microplastics, and discusses the obstacles and uncertainties existing in current soil microplastic research. We have suggested potential research directions for soil microplastics according to the current research gaps. We have also proposed strategies for addressing and managing soil microplastic pollution, aiming to lay the foundation for research on soil microplastic pollution and its prevention and control.

Abstract:【Objective】 A large amount of plastic waste is produced globally every year, and landfill is the most common way to deal with plastic waste. However, plastic waste that enters landfills will continuously generate microplastics under the influence of physical, chemical, and biological factors, thereby affecting the surrounding ecological environment and human health.【Method】 In this study, the occurrence characteristics of microplastics in the soil-groundwater system of a landfill in Taizhou, Zhejiang Province, were investigated, and the ecological risk of microplastics in this area was assessed by pollution load index (PLI), polymer risk index (H), and potential ecological risk index (PERI). 【Result】 The results showed that the abundance of microplastics was 28313±7687 microplastics/kg, 7789±585 microplastics/L, 25660±2614 microplastics/kg, 183±41 microplastics/L in landfill, leachate, soil, and groundwater, respectively. The microplastics were mainly thin film and of a small size (0-50 μm). Also, the polymer composition was mainly polyethylene (PE) and polypropylene (PP). In addition, the microplastic ecological risks of the landfill""s waste, soil, leachate, and groundwater were respectively at extremely high risk, high risk, high risk, and medium risk. 【Conclusion】 Landfill sites, as an important source of microplastics, have potential impacts on the surrounding environment. This study can provide theoretical support for the assessment and control of microplastic pollution in the soil-groundwater system of landfill sites.

Abstract:【Objective】Microplastics are ubiquitous in environments, posing potential threats to ecosystems. As a persistent contaminant, they can undergo aging during prolonged environmental exposure. Aging alters the physicochemical properties of microplastics, thereby modulating their environmental fate and ecological risks. Considering that various environmental factors, including radiation intensity, medium type, humidity, and temperature, play a critical role in the aging process of microplastics, it is evident that the natural aging behavior of microplastics differs significantly from that observed under controlled laboratory aging simulations. However, research on long-term natural aging of microplastics remains limited.【Method】In this study, two typical microplastics, polyvinyl chloride (PVC) and polyamide (PA), were selected. A multi-environment exposure system encompassing atmospheric, topsoil (0 cm), and subsurface soil (10 cm) environments was established to conduct a 12-month natural aging experiment. The physicochemical properties of microplastics before and after aging were characterized using microscopic, spectros-copic, and thermogravimetric techniques, combined with chemical and thermal degradation approaches to evaluat- the stability of aged microplastics.【Result】The results showed that the natural aging behaviors of PVC and PA microplastics differed significantly and were closely dependent on environmental conditions. Specifically, sunlight-induced photo-degradation was the primary natural aging pathway for PVC microplastics. This process was characterized by significant changes in their physicochemical properties, including the formation of oxygen-containing functional groups, the generation of conjugated bonds, and the cleavage of the polymer backbone. These reactions resulted in notable alterations in surface morphology, color, and particle size. Concurrently, atmospheric-exposed PVC microplastics exhibited a significant decrease in stability, as demonstrated by a lower pyrolysis temperature and a higher oxidative degradation rate. In contrast, soil-exposed PVC microplastics (both topsoil and subsurface) exhibited comparable aging levels. While PVC microplastics on the soil surface were also exposed to sunlight, surface attachment to soil particles and the shading effect of plants significantly reduced the extent of their photoaging. Consequently, due to the absence of sunlight-induced photo-aging, the aging level of soil-exposed PVC microplastics was lower than that of atmospheric-exposed PVC microplastics. This suggests that PVC microplastics demonstrate greater persistence in soil environments over extended periods. Atmospheric-exposed PA microplastics underwent marked photodegradation, exhibiting a significant decrease in particle size (P < 0.05). However, carbonyl index (CI) and stability analyses revealed equivalent aging levels between atmospheric- and soil-exposed PA microplastics. This finding is inconsistent with the behavior of PVC microplastics, suggesting that PA microplastics can undergo relatively significant aging even in soil environments lacking direct sunlight exposure.【Conclusion】This multi-environment aging study elucidates the divergent aging behaviors of PVC and PA in natural settings. These findings provide theoretical foundations for refining risk assessment frameworks and optimizing laboratory aging simulations for both microplastic types.

Abstract:Agricultural plastic mulch films, while enhancing crop yields, also cause severe "white pollution." As an environmentally friendly alternative, biodegradable mulches (BDMs) have attracted significant attention in recent years. This paper systematically reviews research progress on the environmental behavior of BDMs in soil, with a focus on analyzing their degradation mechanisms, the release characteristics of microplastics and additives, and their associated environmental risks. BDMs can be degraded through the synergistic action of chemical hydrolysis, photo-oxidation, and microbial enzymatic breakdown; however, the degradation rate is influenced by environmental factors such as soil temperature, moisture, and microbial communities. The degradation process of BDMs typically leads to concentrated releases of microplastics, with their abundance increasing by 30%-50% compared to conventional mulch films. These microplastic fragments can further adsorb other pollutants. BDMs additives are characterized by their diverse types and high actual leaching potential in soil, yet their actual toxicity risks remain unclear. Current research still has shortcomings regarding the "degradation-release-response" cascade mechanism of BDMs, their cross-media migration, and risk assessment. Future efforts require material innovation, in-depth analysis of environmental behavior, and policy coordination to optimize the degradability of BDMs and reduce ecological risks.

Abstract:【Objective】Dissolved organic matter (DOM) plays a crucial role in maintaining soil carbon cycling and ecological functions. The accumulation of microplastics (MPs) in agricultural soils may alter the composition and stability of DOM. However, the mechanisms by which MPs of different polymer types affect DOM characteristics in soils with distinct physicochemical properties remain unclear. 【Method】In this study, two representative paddy soils, including acid paddy soil from Jinhua (JH, pH 5.03) and alkaline paddy soil from Cixi (CX, pH 8.26), were used as test soils. A 60-day microcosm incubation experiment was conducted by adding 0% and 0.5% of polyethylene (PE), polyvinyl chloride (PVC), and polylactic acid-Poly (butyleneadipate-co-terephthalate) (PLA+PBAT, Bio) MPs to investigate the effects of different MPs on soil basic physicochemical properties and DOM characteristics. Ultraviolet-visible (UV-Vis) spectroscopy and Three-Dimensional Excitation-Emission Matrix combined with parallel factor analysis (PARAFAC) were used to characterize variations in the DOM aromaticity, molecular weight, and fluorescent components under different treatments. 【Result】The results revealed that MP-induced effects were more pronounced in acidic JH soil than in alkaline CX soil. Among the treatments, Bio microplastic exerted the strongest influence. Compared to the control, Bio treatment in JH soil increased pH, dissolved organic carbon (DOC) concentration, and spectral slope (SR) by 2.09%, 4.58%, and 8.26%, respectively, while PE and PVC showed relatively minor effects. In the early stage (15 days), MPs significantly decreased SUVA254 values in JH soil, suggesting enhanced degradation or transformation of aromatic DOM components. This inhibitory effect gradually diminished over time. In contrast, no significant effects were observed in CX soil under any treatment. Furthermore, JH soil exhibited continuous declines in pH and SUVA values and an increase in SR during the incubation, indicating a trend toward lower molecular weight and simpler DOM structures. Meanwhile, CX soil maintained relatively stable DOM characteristics throughout the experiment. 【Conclusion】The impact of MPs on soil DOM was strongly influenced by both polymer type and soil properties. Biodegradable MPs, such as Bio, had a more substantial effect on DOM structure than traditional MPs such as PE and PVC. Acidic and coarser-textured JH soil was more vulnerable to MP interference and temporal changes, resulting in increased DOM reactivity and instability. In contrast, alkaline, fine-textured CX soil exhibited greater resistance to MPs-induced perturbations and maintained higher DOM structural stability.

Abstract:Bioplastics are widely used due to their clean raw materials and good degradability. However, the dynamic changes in the physical and chemical properties of materials, especially during photodegradation, as well as the generation mechanism of secondary pollutants and their environmental trends, still lack quantitative evaluation.【Objective】This study investigated the degradation dynamics of three types of bioplastic films (starch based, cellulose based, and polylactic acid based) and a traditional petroleum based polyethylene (PE) film during 0-30 days of light aging, as well as the release of harmful substances such as microplastics and additives, by simulating accelerated degradation experiments under sunlight. 【Result】Scanning electron microscopy (SEM) observed that the density of photo induced cracks on the surface of bioplastic film increased by 2-3 times compared to the initial state after 30 days. Fourier transform infrared spectroscopy (FTIR) showed a 50-80% increase in carbonyl index (CI) (peak intensity significantly increased at 1078 cm ?1), and X-ray diffraction (XRD) analysis showed a 20-35% decrease in crystallinity. The three materials have similar structures, while traditional petroleum based plastics mainly rely on C-C bonds and have relatively weak environmental degradation ability. Quantitative analysis found that among the four materials, starch based biofilm released the highest number of microplastics, reaching more than 7 × 10⁷ pieces. Gas chromatography-mass spectrometry (GC-MS) detection showed the migration of phthalate ester additives (PAEs) in biofilms, among which dioctyl phthalate (DEHP) and dibutyl phthalate (DBP) were released. Although they did not exceed the standard of "Determination of Six Phthalate Compounds in Water Quality by Liquid Chromatography Triple Quadrupole Mass Spectrometry" (HJ 1242-2022), they may still pose environmental risks. 【Conclusion】 Research has shown that although biodegradable films have rapid apparent decomposition characteristics, secondary pollutants such as microplastics, DOM, and PAEs generated during their photodegradation process may form a composite pollution chain, posing a potential threat to soil water ecosystems. It is urgent to strengthen degradation controllability and full lifecycle risk assessment in material design and standard setting.Bioplastics are widely used and researched due to their clean source and good biodegradability.

Abstract:【Objective】Microplastics (MPs) represent a pervasive class of emerging contaminants that have been widely documented across global environmental compartments. Despite this recognition, significant knowledge gaps remain regarding their fate and behavior within fragile karst groundwater ecosystems, particularly those that serve as critical drinking water resources. The unique hydrogeological features of karst systems, characterized by rapid infiltration through fractured limestone, raise serious concerns about MP transport and human exposure pathways. These systems, however, remain severely understudied. This study aims to address these uncertainties through a comprehensive investigation of the occurrence, distribution, underlying mechanisms, and potential ecological and health risks associated with MP contamination in a representative karst groundwater system used for drinking water.【Method】To account for temporal variability in these dynamic systems, we systematically collected water samples every quarter across four seasons (spring, summer, autumn, winter) from both pristine karst springs (Raw Water, RW) and downstream household tap water endpoints (End Water, EW) in a typical karst terrain in Southwest China. Laboratory analyses employed high-resolution microscopic Raman spectroscopy for definitive polymer identification and characterization of isolated MP particles. Subsequent statistical analyses used the Mantel test to rigorously examine correlations between MP concentrations and a suite of water quality parameters. Additionally, the Pollution Load Index (PLI) was calculated to provide an integrated assessment of MP pollution levels and to quantify potential environmental and human health risks. 【Result】The findings revealed significant MP contamination throughout the karst aquifer system. A total of 2,273 MP particles were identified across all 72 water samples. The detected MPs exhibited distinct physical characteristics: fragments were dominant (50.37%), followed by fibers (40.61%). Particle size analysis showed a predominance within the 100–300 μm range (59.08%), and most particles appeared transparent (78.79%) under microscopy. Polymer composition analysis indicated that polyethylene (PE; 44.08%) was the most abundant polymer, followed by polyethylene terephthalate (PET; 35.02%) and polypropylene (PP; 16.89%). The mean MP abundance was 1.58±1.43 items·L?1 across all samples. Notably, significantly higher concentrations were observed in raw water sources (RW: 1.89±1.70 items·L?1) compared to finished tap water (EW: 1.26±1.05 items·L?1), suggesting partial removal during transport or treatment. Pronounced seasonal variations were observed, in the following order: autumn (2.67±2.08 items·L?1) > spring (1.58±1.30 items·L?1) > summer (1.13±0.63 items·L?1) > winter (0.94±0.53 items·L?1) (P < 0.05). The calculated Pollution Load Index (PLI = 1.10) indicated that the current MP pollution level in this karst groundwater system poses a relatively low risk. 【Conclusion】Key correlation analyses provided insight into MP transport mechanisms. A significant positive correlation was found between MP abundance and dissolved organic carbon (DOC) concentrations (P < 0.05), suggesting that organic matter facilitated MP mobilization. A negative correlation was observed between calcium ion (Ca2?) concentration and MP abundance (R2 = 0.40), possibly reflecting interactions influenced by aquifer mineralogy. In contrast, no significant correlation was found between MP levels and antecedent monthly precipitation (P > 0.05), indicating that direct flushing during storm events may not be a major influence. These results collectively underscore that intrinsic water chemistry plays a more decisive role in MP transport and accumulation within karst aquifers than transient hydrological events. Based on these findings, we recommend urgent strengthening of protective measures for karst spring water sources, establishing long-term MP monitoring programs in vulnerable karst regions, and developing mitigation strategies along water supply chains to prevent future escalation of MP pollution risks.

Abstract:Microplastics and nanoplastics (MNPs), defined as plastic fragments, fibers, and particles with diameters below 5 mm and 1 μm, respectively, are widely spread emerging contaminants in soil environments. Due to frequent material exchanges within the soil–plant system, MNPs can be transferred from soil into plants, accumulate and distribute across various plant tissues, and thus pose a potential threat to the health of the soil–plant system. MNPs can significantly alter soil physicochemical properties and migrate from soils into plant tissues, leading to adverse effects on plant growth and physiological-biochemical functions. To overcome the limitations imposed by the complexity of the environmental matrix, advanced labeling techniques provide a fast and efficient way for visually tracking and quantifying MNPs in soil-plant systems, which are essential for deepening mechanistic understanding. This review systematically evaluates four mainstream labeling methods. Fluorescent labeling is cost-effective and easy to implement, but limited by photobleaching and interference from environmental matrices. Metal-based labeling combined with inductively coupled plasma mass spectrometry (ICP-MS) allows for stable quantification, though it may change the physicochemical properties of MNPs. Stable isotope labeling (such as 13C or 1?N) provides high specificity for tracing degradation pathways but faces challenges due to technical complexity and background signals as well. Radioisotope labeling (e.g., 1?C, 3H) offers ultrahigh sensitivity but raises concerns regarding environmental biosafety and high costs. On this basis, this paper focuses on introducing rare earth element labeling technology, which uses the fluorescence properties of lanthanide chelates and their quantifiable characteristics to simultaneously realize visual tracing and precise quantification of MNPs. It is particularly suitable for studying environmental behavior and food chain transmission risks of MNPs in soil-plant systems. In the future, new markers that are more precise and efficient should be developed, and new labeling technologies that combine multiple labeling methods should be developed to more systematically and comprehensively reveal the environmental fate and ecological risks of MNPs, and provide a scientific basis for pollution control of MNPs in soil-plant systems.

Abstract:【Objective】Historically non-sanitary landfills continuously release microplastics(MPs) into adjacent soils due to the absence of impermeable lining systems, thereby exacerbating ecological risks at the site and in surrounding environments. This study aims to investigate the distribution characteristics and ecological risks of MPs in a historically non-sanitary landfill and adjacent farmland soils in Jiashan County, Zhejiang Province, East China. The research aims to identify key pollution sources and evaluate the efficacy of multi-method risk assessment frameworks for informing targeted pollution control strategies.【Method】For landfill sites and surrounding farmland topsoil, the distribution characteristics and ecological risks of microplastic pollution were revealed through the combined application of micro-Fourier transform infrared spectroscopy (μ-FTIR), the Pollution Load Index (PLI), Risk Characterization Ratio (RCR), the Multi-characteristics Potential Ecological Risk Index (MPERI), and Monte Carlo simulation.【Result】(1) Landfill soils exhibited significantly higher MPs abundance (7,425.5–21,306.5 items/kg) than farmland soils (199.5–2,868.5 items/kg). Polyethylene terephthalate (PET) and polyethylene (PE) were the main MP types in both sites (>70% of total MPs). Small-sized MPs (<1 mm) accounted for 70.9% in landfill soil and 66.3% in farmland soil, while transparent MPs comprised 71.8% and 53.1% in landfill and farmland soil, respectively. The landfill was identified as a potential source of farmland MPs. (2) Multi-model risk assessment revealed that PLI classified the landfill as medium-to-high risk and farmland as low-to-medium risk, whereas RCR and MPERI indicated low-to-medium risk for both. Risk escalated significantly at sites containing acrylonitrile resin (PAN). (3) Monte Carlo simulations demonstrated that farmland had a higher probability of low PLI risk than the landfill. Nevertheless, both RCR and MPERI might underestimate ecological risks in the landfill. Sensitivity analysis identified MPs polymer type as the paramount parameter influencing risk outcomes.【Conclusion】The landfill acts as a critical source of MPs contamination in adjacent agricultural soils. Discrepancies in risk outcomes across models highlight the necessity of integrating multi-method assessments with probabilistic approaches (e.g., Monte Carlo) to quantify uncertainties. Polymer type is a decisive factor in ecological risk, necessitating prioritized controls for PAN-containing MPs. This empirical-modeling framework provides a scientific basis for hierarchical management of MPs pollution in non-sanitary landfills and surrounding environments, promoting the application of probabilistic risk models in contaminated sites.

Abstract:Plastic waste degradation in the environment generates microplastics (<5 mm), posing potential risks to soil physicochemical properties, terrestrial ecosystems, and human health. However, current research on the occurrence patterns, source apportionment methods, and environmental risk assessment of soil microplastics remains limited. To support soil microplastic pollution management and remediation, this review synthesizes the occurrence patterns of microplastics from various perspectives including abundance, polymer types, particle size, color and shape. Source apportionment methods, including pollution characteristic analysis, emission inventory, multivariate statistical modeling, and co-pollutant assisted identification are systematically introduced. Furthermore, this review evaluates the advantages and limitations of various risk assessment frameworks for soil microplastics, identifies the main challenges therein, and proposes future research directions. Firstly, there is need to accelerate the establishment of standardized analytical protocols for soil microplastics to provide multidimensional and accurate information for source identification and risk assessment; Secondly, strengthening fundamental research on source apportionment and establishing a robust source information database for soil microplastics is paramount; Thirdly, enhancing the research on risk assessment methods by developing a comprehensive toxicological database, quantifying the synergistic effects of composite pollution and clarifying the influence of factors on environmental risks, such as particle size, shape, color, and aging degree is necessary. These efforts will provide a scientific basis for the effective prevention and control of soil microplastic pollution risks.

Abstract:【Objective】Soil serves as a significant sink for microplastics (MPs), with the annual influx of MPs into soil being 4 to 23 times greater than that entering the ocean. Therefore, the assessment of the potential environmental effects of soil MPs cannot be ignored. As a non-natural carbon source, the precise impact of MPs on dissolved organic matter (DOM) in soil-crop systems remains unclear. 【Method】This study investigated the behavior of conventional MPs (polyethylene, PE; polystyrene, PS) and biodegradable MPs (polybutylene adipate terephthalate, PBAT; polybutylene succinate, PBS; polylactic acid, PLA) in soil using maize-cultivated pot experiments. We measured dissolved organic carbon (DOC) concentration, DOM fluorescence characteristics, and DOM molecular composition and properties in the system after MPs addition. 【Result】The results showed that MPs increased soil DOC content, as well as the humification degree and stability of DOM. Simultaneously, MPs decreased the H/C ratio of DOM molecules and the relative content of amino acid, carbohydrate, and protein-like molecules in the soil-plant system, while increasing the aromaticity index (AI) and nominal oxidation state of carbon (NOSC) values. 【Conclusion】Overall, this study reveals the impact of different types of MPs on DOM components in soil-crop systems, providing an important theoretical basis for the comprehensive assessment of the environmental risks of MPs and the formulation of plastic control policies.

Abstract:With the rapid global increase in the number of motor vehicles, the release of tire wear particles is also growing significantly. Tire wear particles can enter the soil through multiple pathways, such as atmospheric deposition, rainfall, and surface runoff, and pose a potential threat to soil ecosystems. The complexity of separation and detection technologies has limited in-depth research on tire wear particles in soil. In recent years, with the continuous improvement of detection methods, research on the behavior and effects of tire wear particles in soil has developed rapidly. This paper summarized the sources of tire wear particles and their primary pathways into soil, analyzed the key behaviors of tire wear particles and their additives in soil, and reviewed the toxicological effects of tire wear particles and their released compounds on plants, soil fauna, and soil microorganisms. On this basis, it also identified the shortcomings of the current research and proposed future research directions, aiming to support a deeper understanding of the behavioral mechanisms of tire wear particles in soil and their ecological risk assessment.

Abstract:【Objective】Micro- and nanoplastics have emerged as pervasive contaminants in terrestrial ecosystems. However, current research remains disproportionately focused on aquatic environments and food crops, leaving a significant knowledge gap regarding their effects on economically important non-food cash crops like tobacco, which possess high economic value and complex secondary metabolic pathways. This study systematically investigates the physiological and metabolic responses of Nicotiana benthamiana to root exposure of polystyrene nanoplastics (PS-NPs), with a particular focus on organ-specific adaptations in carbon and nitrogen metabolism under stress. Understanding these mechanisms is critical for ecological risk assessment and for safeguarding the productivity and quality in non-food cash crop systems, which have been largely neglected in the current nanoplastic research paradigm. 【Method】We employed a dual experimental approach integrating both pot cultivation and hydroponic systems to comprehensively evaluate PS-NPs effects on N. benthamiana seedlings. This integrated design enabled us to distinguish direct particle-plant interactions under controlled hydroponic conditions from more complex soil-mediated effects in pot environments. We employed metabolomics analysis coupled with detailed physiological analyses, including oxidative stress markers, antioxidant enzyme activities, and biomass measurements, to unravel the metabolic and defense networks activated under PS-NPs stress. 【Result】Pot experiments revealed a clear dose-dependent inhibition of plant growth, with PS-NPs concentrations of 150, 500, and 800 mg·kg-1 reducing plant height by 18.80%, 29.42%, and 30.67%, respectively. Hydroponic exposure induced even more striking morphological alterations, characterized by significant shoot suppression accompanied by a remarkable 43.52% and 47.20% increase in root elongation at 50 and 150 μg·mL-1. Paradoxically, the shoot fresh weight increased while dry weight accumulation was markedly reduced, indicating fundamental disruptions in carbon partitioning and structural biomass synthesis. Physiological analyses demonstrated severe oxidative stress in N. benthamiana roots, evidenced by elevated hydrogen peroxide and malondialdehyde levels alongside significantly enhanced superoxide dismutase activity, indicating activation of the antioxidant defense system. Metabolomic profiling identified extensive perturbations across multiple pathways, particularly in amino acid metabolism, carbohydrate dynamics, and organic acid transformation. It indicated that PS-NPs exposure disrupted central carbon metabolism, including carbon metabolism, galactose metabolism, and energy production pathways through glycolysis and oxidative phosphorylation. Moreover, N. benthamiana roots exhibited substantial downregulation of critical TCA cycle intermediates, including citrate and α-ketoglutarate, coupled with reduced glycolytic intermediates such as glucose-6-phosphate and fructose-6-phosphate, while simultaneously accumulating compatible solutes like isoleucine and valine. This result indicates strategic reallocation of nitrogen resources toward osmotic protection and fundamental defense mechanisms. Conversely, N. benthamiana leaves implemented an efficient carbon sequestration strategy, accumulating hexose phosphates and soluble sugars, and upregulating the biosynthesis of specialized defensive compounds, including flavonoid secondary metabolites and non-protein amino acids, demonstrating organ-specific metabolic specialization. Importantly, nitrogen metabolism of N. benthamiana leaves also shifted toward active defense and signal transduction. The pronounced upregulation of 4-aminobutyric acid (GABA) and its derivative 2,4-diaminobutyric acid marked the activation of the GABA pathway, a pivotal stress-response pathway. This pathway plays a crucial role in the reconstruction of carbon and nitrogen balance, and also assumes core functions in mitigating oxidative stress and regulating signal transduction within the N. benthamiana defense network. 【Conclusion】 This study demonstrates that PS-NPs root exposure initiates a complex adaptive response in N. benthamiana seedlings, characterized by inhibited shoot growth and dry matter accumulation, and stimulated root elongation as a stress-avoidance mechanism. PS-NPs root exposure also induced oxidative damage and triggered the comprehensive reorganization of metabolic networks. The research reveals an organ-specific defense strategy wherein roots prioritize immediate survival through osmotic adjustment and basic defense, while the leaves activate advanced chemical defense pathways, coordinated in part through GABA-mediated signaling. This study provides novel mechanistic insights into the metabolic adaptation of plants under nanoplastic stress and offers an important scientific basis for assessing the potential ecological risks of micro- and nanoplastics in terrestrial environments.

Abstract:【Objective】Tire wear particles (TWPs) are key sources of microplastic pollution, and their long-term impact on human health and the environment is receiving increasing attention. 【Method】This study investigated the release of heavy metals and sulfur from TWPs in soil, as well as their effects on soil physicochemical properties and fertility. It was also explored the role of different aging processes (photo-aging, lake water aging, and snowmelt water aging) on the properties of TWPs and their effects on soil fertility. Through laboratory simulations, fresh and aged TWPs were prepared and incubated in soil for various periods. 【Result】The results indicated that aging significantly altered the physicochemical properties of TWPs, including surface morphology, functional groups, and specific surface area, which in turn affected their heavy metal and sulfur release behavior in soil. After the addition of TWPs to the soil, a decrease in soil organic matter (OM) content was observed, although the impacts on cation exchange capacity (CEC) and pH were minimal. At the same time, TWPs significantly increased the content of available phosphorus and alkali-hydrolyzable nitrogen in the soil, with a slight impact on available potassium. The effects of TWPs on soil physicochemical properties and fertility varied under different aging processes, with photo-aging and snowmelt aging showing the most pronounced effects. Pearson correlation analysis revealed a significant internal relationship between the physicochemical properties of TWPs and the soil response. As TWPs were incubated in soil for longer periods, their adverse effects on soil fertility indicators, especially OM, gradually intensified. Furthermore, TWPs may interfere with soil nutrient cycling, particularly nitrogen cycling, by affecting CEC. 【Conclusion】This study provides important insights for understanding the long-term ecological impact of TWPs on soil and offers a basis for accurate risk assessment.

Abstract:【Objective】Microplastic pollution has emerged as a significant global environmental issue, with fibrous microplastics constituting a substantial portion of this pollutant. These tiny fibers, often derived from synthetic textiles and industrial processes, can infiltrate various ecosystems, including soil and water. Understanding the behavior and fate of fibrous microplastics in plants is crucial to assessing their potential ecological risks and human health implications. This study aimed to investigate the uptake and transport of polyacrylonitrile (PAN) fibrous microplastics in corn plants, a widely cultivated crop. 【Method】To achieve this, PAN microfibers, with an average diameter of 200 nm and an aspect ratio of 20±5 were synthesized using electrostatic spinning and fluorescently labeled to facilitate tracking. Corn seedlings were exposed to these labeled fibers under hydroponic conditions for two weeks. The distribution and localization of the fibers within the plant tissues were subsequently examined using laser confocal microscopy and scanning electron microscopy. 【Result】The results revealed that the PAN microfibers were able to penetrate the root interior through nascent lateral root fissures. Once inside the root, the fibers were transported upward along the xylem ducts to the stems. However, the fibers were not detected in the vascular tissues of the leaves, suggesting that their translocation was primarily restricted to the root and stem systems. The ability of corn roots to absorb and accumulate these fibers highlights the potential for microplastic bioaccumulation in plant tissues. Also, the large surface area of fibrous microplastics may have contributed to their efficient adsorption by root surfaces, facilitating their entry into the plant whereas the fibrous morphology enhanced their penetration through root tissues. In addition, the accumulation of fibrous microplastics in plants could potentially disrupt plant growth, development, and physiological processes. 【Conclusion】This study provides the first direct evidence of fibrous microplastic uptake and transport in higher plants, and highlights the possible transfer of fibrous microplastics from plants to herbivores and humans through the food chain. The research results provide an important scientific basis for in-depth understanding of the migration and transformation laws of different shapes of microplastics in plant-soil systems, and also provide support for an assessing their impact on ecological environmental health and food safety. Our results necessitate the need for further research to investigate the factors influencing fibrous microplastic uptake and transport in plants, the potential ecological and toxicological impacts of fibrous microplastic exposure, and effective strategies for minimizing their environmental and human health risks.

Abstract:【Objective】The extensive use of plastic film in Xinjiang has led to the accumulation of a large amount of microplastics (MPs) in farmland soil, causing changes in soil physical and chemical properties and affecting crop yields. 【Method】In this study, the interaction effect of the particle size and content of polyethylene microplastics (PE-MPs) on soil physical properties was systematically investigated by simulating the residual environment of microplastics in farmland. By designing different microplastic content and particle size treatment test groups and comparing their indicators with the blank control group, the impact of microplastics on soil physical properties was evaluated. 【Result】The results showed that PE-MPs significantly changed soil thermal dynamics, structural stability and water transport characteristics through size-content synergism: In terms of temperature control, microplastics reduce thermal conductivity by increasing surface roughness and porosity, and increase the daily average temperature of 5 cm soil layer by 0.97 ℃ (1 700 μm-1% treatment), and the thermal effect decreases with depth (0.67–0.93 ℃ decrease with 25 cm). In terms of structural remodeling, the treatments of large particle size (≥550 μm) and high content (≥0.25%) significantly reduced the bulk density, increased the porosity (55.62%-59.41% in the 1 700 μm treatment group), and promoted the formation of large aggregates (>0.2 mm) by physical adsorption (93% increase in proportion, mean weight diameter up to 3.70 mm); The water transport characteristics show that the water loss rate of large particle size microplastics (≥550 μm) is 1.2 times higher than that of 48 μm treatment due to the formation of millimeter cracks at low content (0.1%-0.25%), and the particle size effect is covered at high content (1%). Correlation analysis further revealed the nonlinear coupling mechanism of soil parameters. Correlation analysis further reveals the nonlinear coupling mechanism of soil parameters, with a highly significant positive correlation between the proportion of large aggregates and average particle size, and a negative correlation between bulk density and porosity.【Conclusion】It is pointed out that when the particle size is >550 μm and the content is >0.25%, microplastics may lead to ecological risks such as soil erosion resistance degradation and hydrothermal coupling imbalance by reconstructing pore network and aggregate bridging structure. In the future, it is necessary to combine microbial function and crop physiology studies to quantify the cascade effect of microplastic pollution, and provide cross-scale theoretical support for farmland pollution control and risk assessment.

Abstract:Microplastic pollution has emerged as an environmental issue requiring urgent attention in farmland ecosystems, involving multiple interdisciplinary fields such as soil science, environmental science, plant physiology, and ecotoxicology. This review systematically summarizes the transformation processes of microplastics at different interfaces within farmland soil–crop systems, with a focus on the transformation mechanisms and migration pathways occurring at the soil–liquid, soil–root, and root–stem interfaces. It further outlines the accumulation characteristics of microplastics within plants and their transfer behaviors in the “soil–crop–animal” food chain. The behavior of microplastics in the rhizosphere and within plants exhibits pronounced particle size effects, material-specific properties, and bioregulation features, enabling them to cross plant root barriers and migrate to edible tissues, thereby potentially posing risks to animal and human health via food chain exposure. Future research should strengthen the understanding of interface transformation mechanisms and in-plant migration pathways of microplastics in farmland soil–crop systems, with particular emphasis on their ecotoxicity, bioavailability, and risk thresholds. Such efforts will facilitate comprehensive assessments of food chain exposure and the development of pollution control technologies, providing a scientific basis for agricultural environmental safety and human health protection.

Abstract:【Objective】Biodegradable plastic mulch films, which are representatively made from polybutylene adipate co-terephthalate (PBAT), have been widely used in the agricultural areas of northwest China. As a result, a large quantity of nanoplastics is left in the local soils. However, the effect of these nanoplastics on the properties of this predominantly clay soil remains understudied. 【Method】This study used clays separated from saline-alkaline soils from northwest China and PBAT-based biodegradable nanoplastics (PBAT-BNPs) as research objects. Clay rewetting was conducted to simulate the soil moisture changes during the agricultural irrigation period in Xinjiang. The effects of PBAT-BNPs on the aggregation behavior and physicochemical properties of sterilized high saline-alkaline clays were explored. 【Result】 The results showed that rewetting significantly promoted the aggregation of clays, which was further enhanced by PBAT-BNPs but was hindered by the high salinity-alkalinity of clays. During the rewetting treatment period, the cation exchange capacity of PBAT-BNP-added clays increased significantly, whereas their electrical conductivity and pH decreased noticeably. The acidic environment induced by PBAT-BNPs facilitated the dissolution of clay minerals and the release of silicate ions. Under the rewetting condition, the Al cations promoted the formation of aggregates through flocculation. Meanwhile, the release of PBAT monomers and soluble ions from clays led to a significant increase in the interlayer spacing of minerals. 【Conclusion】 This study provides a new perspective on the abiotic impacts of biodegradable nanoplastics on soil properties.

Abstract:Microplastics have emerged as a widespread pollutant in agricultural soils, entering primarily through plastic film mulching, sewage irrigation, and the application of organic fertilizers. Their continuous accumulation poses a growing threat to soil ecosystem health and functionality. Therefore, a deep understanding of the impact process and mechanism of microplastics on the functioning of agricultural soil ecosystems is of great scientific significance and practical value for scientifically assessing their ecological and environmental risks, developing pollution control and remediation strategies. This review systematically examines the migration and transformation behavior of microplastics in agricultural soil and analyzes their diverse ecological effects, including alterations to soil physicochemical properties, shifts in microbial communities, impacts on soil fauna, and influence on crop growth. It also synthesizes current knowledge regarding the broader implications of microplastics on soil nutrient cycling, greenhouse gas emissions, crop productivity, and overall soil health. On this basis, key scientific questions are identified in areas such as the complex environmental behavior mechanisms of microplastics in real environments, inter-trophic interactive effects, and the systematic assessment of ecological risks and soil health. Finally, future research priorities and directions are proposed to provide a theoretical foundation for risk prevention and green remediation of microplastic pollution in agricultural soils.

Abstract:【Objective】Microplastic (MP), with its small size and low degradability, is recognized as a potential persistent organic pollutant in terrestrial ecosystems. MP enters terrestrial ecosystems and affects the soil nitrogen cycling process by changing the soil’s physical, chemical, and biological properties. These changes affect soil N2O emission. Despite having gained global attention, the key factors and mechanism of MP influence on soil N2O remain unclear. Therefore, this study aimed to investigate the effects of MP size and concentrations on N2O emission from agricultural soils at different temperatures and thus explore their potential mechanism. 【Method】Agricultural soils were collected from plots in South China for indoor culture experiments, and five different treatment sets were selected under three temperature gradients (10 ℃, 20 ℃ and 30 ℃): (1) no microplastics (CK); (2) addition of microplastics with a mass concentration of 0.1% and a particle size of 74 μm (Nlp-0.1%); (3) addition of microplastics with a mass concentration of 0.5% and a particle size of 74 μm (Nlp-0.5%); (4) addition of microplastics with a mass concentration of 0.1% and a particle size of 25 μm (Nsp-0.1%); and (5) addition of microplastic with 0.5% mass concentration and a particle size of 25 μm (Nsp-0.5%). Afterward, soil N2O concentration as well as inorganic nitrogen and microbial functional genes were determined. 【Result】Elevated temperature significantly increased soil N2O emissions from agricultural soils (P < 0.001), and the cumulative soil N2O emissions at 30 ℃ were 43.3 and 6.3 times higher than those at 10 ℃ and 20 ℃, respectively. In addition, soil NO– 3-N content gradually increased with increasing temperature. The abundance of AOB amoA, Comammox (com2), nirS, nirK, and nosZ functional genes was the highest at 20℃ and lowest at 30℃. The effects of MP of different sizes on soil N2O emissions and related nitrogen cycle functional genes varied widely. Compared with the CK treatment, the Nlp treatment significantly increased soil N2O emission by 37.5% and 838.7% at 10 ℃ and 20 ℃ (P＜0.001). The Nsp treatment significantly decreased the abundance of com2 and nirK functional genes but significantly increased the abundance of nirS functional genes in soil (P＜0.001). The correlation and random forest analyses showed that soil N2O emission was significantly and positively correlated with temperature and the concentration of NO– 3-N, but significantly and negatively correlated with the abundance of AOA amoA, nirK, nirS, and nosZ functional genes (P＜0.05). Furthermore, it was observed that the nosZ functional genes and temperature were the main factors affecting soil N2O emission. 【Conclusion】Elevated temperatures significantly increased N2O emissions from agricultural soils, and different particle sizes and concentrations of MPs had different effects on soil N2O emissions, and there was an interaction effect between microplastics and temperature. The results of this study can provide a scientific basis for investigating the mechanism of MP on N2O emissions from agricultural soils under global warming conditions and for risk assessment.

Abstract:【Objective】Microplastics (MPs) and neonicotinoid pesticides are widespread pollutants in agricultural soils, however, their interactions have not been fully studied. Thus, this study aims to explore the interactive mechanisms between biodegradable MPs [poly(butylene succinate), PBS] and neonicotinoid pesticide (thiacloprid, THI). 【Method】The interactive and adsorption mechanisms of THI on PBS were investigated through adsorption kinetics and isotherm models by considering the influence of common environmental factors like pH, salinity, and dissolved organic matter. Also, the desorption of pre-adsorbed THI from PBS using pure water and simulated intestinal fluid (SIF) as background solutions was evaluated. In addition, the bioavailability of THI in red and black soils treated with different proportions of PBS was compared and analyzed using thin film diffusion gradient (DGT) technology. 【Result】The results revealed that the adsorption process of THI on PBS was consistent with the pseudo-second-order kinetic model, indicating that chemical adsorption was predominant. Also, the adsorption isotherm analysis indicated that the adsorption of THI by PBS was multi-layered, and the experimental data fitted both the Henry and the Freundlich models well (R2 > 0.99). The results also showed that an increase in pH and salinity promoted the adsorption of THI while changing the concentration of dissolved organic matter had little effect on the adsorption process. Furthermore, the desorption experiments found that using SIF, the maximum amount of THI desorbed was 39.4 μg?g-1, which was 1.16 times higher than that desorbed by pure water, suggesting that THI is more easily desorbed in the SIF environment. Using the DGT technology, it was observed that the bioavailability of THI in soil increased after the addition of PBS, and the increase became more significant as the ratio of PBS added was increased. 【Conclusion】PBS can adsorb and desorb THI, and when added to soil, PBS can affect the bioavailability of THI. These findings provide important information for understanding the impact of MPs on the environmental behavior of neonicotinoid pesticides under actual environmental conditions and offer a new perspective on the environmental risk assessment and management of pesticides.

Abstract:【Objective】Microplastic and heavy metal pollution are global problems that threaten ecosystems and human health. Microplastics in soil can interact with soil particles and affect the physicochemical properties of soil, which in turn affects the behavior of heavy metals in soil. 【Method】This study systematically investigates the sorption-desorption behavior of polyamide (PA) microplastics toward cadmium (Cd2+), chromium (Cr3+), and copper (Cu2+) using Guizhou yellow soil as the research object. By simulating PA"s natural aging processes through multiple freeze-thaw cycles, high-temperature exposure, and oxidation, the aging mechanisms and adsorption mechanisms are elucidated. 【Result】The results showed that the adsorption process of PA on the three heavy metals could be divided into two stages: rapid adsorption (0-90 min) and slow adsorption (90-150 min), and the adsorption amount reached more than 99% of the saturation amount. Also, the kinetic behaviors conformed to the pseudo second order model (R2 > 0.999), which indicated that chemosorption was the dominant mechanism. Moreover, the adsorption data fitted better the Langmuir model compared to the Freundlich model (R2 > 0.978), and PA significantly enhanced the adsorption capacity of Cr3+ from the soil (KL value increased by 59.1%). After 21 days of aging, PA surface roughness, crystallinity, specific surface area (+44.49%), and negative charge density (?36.53 mV) increased significantly, resulting in an increase in heavy metal adsorption (P < 0.05) and a decrease in desorption. The largest decrease in desorption was observed for Cd2+ (18.7%) and the smallest for Cr3+ (4.2%). Furthermore, carboxyl (?COOH) and hydroxyl (?OH) groups generated by oxidizing the PA surface during aging strengthened heavy metal immobilization through coordination and electrostatic interactions, whereas the increase in the proportion of crystalline regions further inhibited desorption. 【Conclusion】 This study reveals the mechanism of adsorption enhancement of soil heavy metals by aged PA, which provides a theoretical basis for the risk assessment and management of microplastic-heavy metal composite pollution in karst areas.

Abstract:【Objective】This study aimed to investigate the absorption and transport characteristics and mechanism of microplastics of different concentrations and particle sizes in maize seeds and seedlings.【Method】Maize was used as the test material and fluorescent-labelled polystyrene microplastics (PS-MPs) microspheres were added to the seeds during germination and to the seedlings during hydroponic exposure. This platform quantified growth-suppressive impacts of the test compound on germinative capacity and early seedling establishment, and clarified its mechanism of action.【Result】The effects of microplastics on the germination of maize seeds and the growth of seedlings exhibited significant dependence on concentration and particle size. At the seed germination stage, when examined using laser confocal electron microscopy, it was found that PS-MPs fluorescent microspheres were enriched at the position of the root hairs on the embryonic root. Furthermore, some of the microspheres penetrated the root epidermis and entered the cortical tissue, ultimately reaching the xylem vessels that are responsible for transporting water and nutrients. Their presence in these critical conductive tissues disrupted the seed germination process and induced oxidative damage. This experiment demonstrated that low concentrations (20 mg·L-1) of fluorescent PS-MPs promoted germination, whereas medium-to-high concentrations (50 and 100 mg·L-1) inhibited it.【Conclusion】This study verified the internalization and shootward translocation of microplastics in maize plants and provided preliminary insights into the absorption and translocation characteristics of microplastics within maize plants. It also shed light on the toxic mechanisms of microplastics on maize, providing a vital experimental basis for understanding the migration and transformation patterns of microplastics within plants, thus providing scientific evidence with which to assess the impact of microplastics on agricultural ecosystems and food safety.

Abstract:【Objective】The accumulation of nanoplastics (NPs) in soils poses potential threats to earthworm health. As key indicator species in soil ecosystems, earthworms play a crucial role in assessing the ecological risks associated with soilborne NPs. However, the quantification of NPs in complex biological and environmental matrices has remained a major challenge, limiting progress in this research field. Therefore, a comprehensive understanding of the absorption and excretion process of NPs by earthworms is essential for accurate exposure risk assessment.【Method】In this study, europium-labeled polystyrene nanoparticles were utilized as model NPs to quantitatively investigate the absorption, distribution, and excretion kinetics of NPs in earthworms. The organisms were exposed to the nanoparticles via three distinct administration routes: topical application onto the epidermis, direct injection into the body cavity, or introduction into the soil medium with or without oral exposure restriction (mouth sealing).【Result】Skin exposure experiments demonstrated that NPs were capable of penetrating the earthworm epidermal barrier, with absorption kinetics exhibiting a biphasic pattern: an initial rapid phase (0-3 h), primarily driven by concentration gradient–mediated passive diffusion, followed by a slower phase (3-24 h), significantly impeded by the resistance of the epidermal mucus layer and NP aggregation. Body cavity exposure studies revealed that NPs excretion via the skin also followed a biphasic pattern, characterized by rapid clearance (28.7% ± 1.4% within 3 h) and subsequent slow attenuation. The skin exudation rate was markedly lower than the penetration rate, indicating that the skin predominantly functions as an absorptive interface during NPs metabolism. Integrated sealing experiments further clarified the time-dependent shift in NPs uptake pathways: cutaneous absorption dominated during the early exposure phase (<3 h), accounting for 70.3%, whereas dietary intake became predominant after 24 h, contributing 62.5%. Notably, dermal penetration efficiency exhibited a clear dose-dependent trend, with NPs displaying organ-specific accumulation patterns in earthworms, the intestine being the primary target organ. These findings demonstrate that nanoscale plastic particles are capable of traversing the epidermal barrier of earthworms, undergoing trans-epidermal transport from the outer layer to internal tissues, as well as retrograde exudation from the inner epidermis. The significantly higher skin penetration rate compared to the exudation rate suggests that the epidermis primarily functions as an absorptive interface during NPs metabolism. Under conditions of reduced or ceased feeding activity, dermal absorption emerges as the predominant pathway for NPs uptake and accumulation in earthworms, which can be attributed to the prolonged dermal exposure to NPs in the surrounding soil environment.【Conclusion】This study highlights dermal penetration as a critical yet previously underestimated route for the uptake of NPs in earthworms, thereby providing a robust scientific basis for refining ecological risk assessment models of soilborne nanoparticles. It also contributes valuable theoretical insights into the biogeochemical cycling of NPs within soil ecosystems.