Effects of Microplastic Fibers and Drought on Plant Communities

Risks of biodegradable films: The time-lagged release of phthalic acid esters and organophosphates esters under realistic agricultural environments

Agricultural plastic films, while boosting crop productivity, may pose significant environmental risks due to additive release during crack degradation. Phthalic acid esters (PAEs) and organophosphate esters (OPEs), widely used as plasticizers and flame retardants respectively, represent two additive categories of the greatest environmental concern due to their persistence and endocrine-disrupting properties. This study systematically investigated the dynamic release of PAEs and OPEs from polyethylene (PE) and biodegradable poly (butylene adipate-co-terephthalate)/polylactic acid (PBAT/PLA)-based films under four simulated agricultural conditions: Natural conditions (NC), UV irradiation (UV), high temperature (HT), and flooding (FC). Uncultivated soil exhibited Σ8PAEs and Σ7OPEs approximately of 1317.5 ng/g and 1931.1 ng/g, respectively. During a 360 d incubation period, the contents of PAEs in soil surged during a short-term period, which may link to the desorption of adsorbed contaminant. Biodegradable films released higher PAEs concentrations than PE films, with secondary contamination peaks emerging 180-360 d post-incubation. Scanning electron microscopy (SEM) observations revealed that structural degradation (e.g., cracks/holes) during early degradation (0-180 d) unexpectedly amplified additive leaching in later stages, contrasting with assumptions of reduced contamination risks over time. UV irradiation had a photo-degradation effect on PAEs further accelerated the release of pollutants by 25-40 %, while high temperature and flooding conditions showed limited promoting effects along with NC conditions. These findings highlight the need for additive-free formulations and environment-specific mulch management policies to mitigate soil contamination risks.

Bipartite trophic levels cannot resist the interference of microplastics: A case study of submerged macrophytes and snail

Some studies frequently focus on the toxic effects of compound pollution formed by microplastics and other pollutants on individual organisms, but it is still unclear how multi-trophic level organisms in compound communities resist the stress of microplastics. Thus, this research used a dose-response experiment (0, 0.1, 0.2, 0.5, 1 mg L-1) to illustrate the influences that microplastics might have on two symbiotic freshwater organisms Vallisneria natans and Sinotaia quadrata. The results showed the reduction of V. natans biomass in 0.5 and 1 mg L-1 groups (28-38 %), and disturbances on the photosynthetic system, reduced the chlorophyll content (15-85 %) and maximum quantum yields (10-31 %). In the case of S. quadrata, which subsisted by scraping leaf biofilms, there was a disruption in the functioning of the antioxidant system. Concurrently, the activities of digestive and neurotransmitter enzymes were affected, potentially leading to detrimental impacts on the organism's essential physiological processes. The introduction of microplastics significantly enhanced the relative abundance of specific microbial taxa, such as Proteobacteria within the biofilm of V. natans leaves and chloroflexi in the rhizosphere, thereby altering the microbial community assembly process. This means the potential ecological functions with microbes as the carrier was influenced. These results indicated that microplastic in aquatic environments can impact the metabolism, autotrophic, and heterotrophic behavior of double-end trophic organisms through symbiotic activities. Therefore, our study reveals how polystyrene microplastics affect the growth of submerged aquatic plants and snails, and from the perspective of community integrity and health, the introduction of these pollutants into freshwater environments may cause disruptive effects.

Nanoplastic and phthalate induced stress responses in rhizosphere soil: Microbial communities and metabolic networks

The widespread use of plastic products in agriculture has introduced micro-nano plastics (MNPs) and dibutyl phthalate (DBP) into soil ecosystems, disrupting microbial communities and altering metabolite profiles. However, their effects on the rhizosphere soil characteristics of medicinal plants like dandelion remain understudied. This study systematically examined the impact of PS NPs and DBP on rhizosphere microbial communities and metabolites by integrating high-throughput sequencing with liquid chromatography-mass spectrometry. Results demonstrated that individual and combined exposures to PS NPs and DBP decreased soil pH, organic matter content, and enzyme activities while reshaping the diversity, structure, and composition of rhizosphere bacteria and fungi. Notably, bacterial network stability and complexity increased under combined exposure, while fungal networks became more simplified, with a 33.72 % decrease in positive correlations. We identified potential PS NPs and DBP-degrading bacteria and biomarkers, including Nocardioides, Pseudarthrobacter, and Arenimonas. We revealed that co-exposure elevated differential soil metabolites associated with tyrosine metabolism and steroid biosynthesis. The significant positive associations between rhizosphere microorganisms and metabolites highlighted that metabolite accumulation was a key microbial response mechanism to stress. However, within the complex soil environment, the compensatory actions of microorganisms and metabolites were insufficient to mitigate the detrimental effects of PS NPs and DBP, resulting in continued inhibition of dandelion growth by 38.66 %. Consequently, these findings highlight that soil fungi and metabolism play key roles in responding to stress and influencing crop growth, providing novel insights into the impact of nanoparticle and plasticizer exposure on medicinal plant cultivation.

Polypropylene microplastics reshape diazotrophic community composition and interactions in the plastisphere without affecting the rhizosphere of Capsicum annuum L

Interactions between microorganisms and microplastics play a crucial role in soil biological processes; however, the response of microbial functional groups in the presence of microplastics (MP) remains unclear. In this study, we investigated the diversity and composition of free-living nitrogen-fixing microorganisms (diazotrophs) in the rhizosphere and plastisphere of pepper (Capsicum annuum L.) across three growth stages under MP stress, using an optimized pipeline for functional nifH gene sequence analysis. Our results showed that MP addition suppressed plant growth, although soil properties were not significantly altered, except for soil pH, which was significantly reduced at each plant growth stage. Notable differences in diazotrophic community composition were observed between the rhizosphere and plastisphere, with the genus Rubrivax exhibiting a significantly lower relative abundance in the plastisphere. Moreover, we found strong deterministic assembly processes and intense network structures of diazotrophs in the plastisphere. Interestingly, MP addition did not significantly alter the diversity, composition, or network properties of diazotrophic communities in the rhizosphere compared to control soils. Our study provides insights into the interactions between microbial functional groups and microplastics, enhancing our understanding of the biological processes that drive ecological nutrient cycling and balance in changing environments.

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.

Regulation strategies of microplastics with different particle sizes on cadmium migration processes and toxicity in soil-pakchoi system

It is still unclear whether there are differences in the effects of microplastics with different particle sizes on the environmental behavior of cadmium (Cd) in the soil-crop system. By introducing the polystyrene microplastics (PS-MPs) with 0.2, 2, and 20 μm, this study explored the regulation strategies of different-sized MPs on the migration and toxicity of Cd in the soil-pakchoi system. Compared to the Cd treatment, the mobility factor of Cd in the soil decreased by 12.97 %, 34.73 %, and 40.12 % with increasing particle sizes of PS-MPs, while the relative binding intensity increased significantly. The 0.2 μm PS-MPs had no effect on Cd content in pakchoi, however, 2 and 20 μm PS-MPs significantly reduced the Cd content in shoots and roots of pakchoi by 47.40 %-29.67 % and 44.56 %-20.92 %, respectively. Additionally, 20 μm PS-MPs reduced the enrichment of the heavy Cd isotope in pakchoi. The results of principal component analysis (PCA) and structural equation modeling (SEM) indicated that 2 and 20 μm PS-MPs may promote the growth of pakchoi by regulating soil properties, nutrient uptake, Cd accumulation, and antioxidant system activity. This study provides evidence for the importance of particle size of MPs in regulating the environmental behavior of heavy metals.

Vertical distribution of microplastics in soil affects plant response to microplastics

The impacts of microplastics on plants have been extensively researched, yielding a variety of responses: promoting growth, limiting growth, or causing no change in plants. Experimental studies, following basic principles of ecotoxicology, typically use a homogeneous distribution of microplastics in soils, where soil and microplastic are well-mixed. However, in the environment, plastic is not homogeneously distributed. Therefore, we tested whether the distribution of microplastics in soils affects the impact observed on plants. For this purpose, we tested the effect of homogeneously distributed microplastics and heterogeneously distributed microplastics (at different levels) on the growth of spring onions. In addition, the presence of drought was also included in our greenhouse experiment. The results show that the distribution of microplastics (whether it is homogeneous or heterogeneous) affects the growth of spring onions differently, especially the shoot and root mass. First, differences of 21-22 % in shoot mass and 29-38 % in root mass were observed between heterogeneously distributed treatments and the homogeneous treatment. Second, under drought conditions, the effects -particularly on shoot mass and the C:N (carbon:nitrogen) ratio- may differ compared to non-drought. Differences of 30-37 % in shoot mass, and up to 16 % in the carbon/nitrogen ratio were observed between different heterogeneously distributed treatments and the homogeneous treatment in the drought case. In addition, shoot mass and the C:N ratio varied depending on drought conditions. Our results strongly suggest that future experiments on microplastic effects in soil should consider at least vertically heterogeneity of the pollutant to arrive at more realistic effect estimates.

Arbuscular mycorrhizal fungi improve treatment performance and vegetative resilience in constructed wetlands exposed to microplastics

Microplastics are increasingly present in municipal wastewater and wastewater treatment plant effluent, prompting the use of constructed wetlands (CWs) for additional treatment. Enhancing CWs with arbuscular mycorrhizal fungi (AMF), known to aid nutrient removal and alleviate plant pollution stress, is gaining interest. This study is the first to examine the influence of two microplastic polymers (polyethylene microspheres and polyester microfibers) at concentrations of 0.1 and 1 mg/L on nutrient removal, plant health, and microbial composition in AMF-inoculated CWs. The results indicate that AMF inoculation combined with microplastic treatments significantly enhances nutrient removal in wetlands, achieving a 45.7% increase in total nitrogen removal and a 25.3% increase in phosphate removal. The effects of microplastics on plant health vary depending on the inoculation status, with an increase in lipid peroxidation (73.4% ± 25.4), and a decrease in the effective quantum yield of PSII (13.4% ± 5) observed in all treatments. High concentrations of polyester microfibers significantly altered the microbial community, increasing AMF colonization frequency and microbial richness, decreasing evenness and the abundance of denitrifying genera, and creating distinct clusters in beta diversity analysis. AMF inoculation maintained higher species richness and evenness, contributing to the resilience of CWs to microplastic pollution. Overall, AMF-inoculated wetlands and plants showed superior treatment performance, highlighting the successful bio-augmentation potential of this approach.

The impact of building uses on microplastic pollution and its implications for environmental education

Rivers are major sources of marine microplastics. To investigate the influence of building use on river microplastic pollution, this study focused on the Chongqing section of the main stream of the Yangtze River. Surface water and sediment microplastic samples were collected and analyzed alongside building use data to explore the relationship between microplastic abundance and building use at different spatial scales. The results showed that: (1) The abundance of microplastics in surface water and sediment in the Chongqing section of the Yangtze River exhibited an inverse distribution pattern. In the upper reaches, the central urban area of Chongqing showed significantly higher microplastic levels in surface water (6,811 ± 3,101 n/m ³) compared to the lower reaches, confirming the direct input effect of high-intensity human activities. The accumulation of microplastics in sediment was greater in the northeastern section of Chongqing compared to the lower reaches (89.6 ± 69 vs. 45.4 ± 28 n/kg), indicating a hydrodynamic-driven sedimentation lag effect. (2) The influence of building use on microplastic abundance in surface water was significantly scale-dependent. Industrial buildings within a 2 km buffer zone explained up to 61.16% of the observed variance, suggesting cross-medium migration through atmospheric sedimentation and sewage pipe network. (3) Compared to land use types, building uses dominate the abundance distribution of microplastics in surface water at larger buffer radius (1-2 km), indicating that high-intensity human activities have a greater impact on spatial differentiation of microplastic pollution. It is recommended to implement hierarchical control measures along the Chongqing section of the Yangtze River. A 2-km ecological buffer zone is set up in industrial agglomeration areas to strictly supervise wastewater discharge from plastic products enterprises. Rainwater bioretention facilities are built within 1 km of densely populated areas to intercept microplastics from domestic sources, such as laundry fibers. This study explores the mechanism by which building use affects river microplastic pollution, providing valuable insights for microplastics control in large river basins worldwide.

The coexistence characteristics of microplastics and heavy metals in rhizomes of traditional Chinese medicine in mulch planting area

Rhizomatous traditional Chinese medicines (RTCMs) are widely crushed into powder and swallowed directly as medicine and food or health products to treat various diseases; however, they may contain toxic microplastics (MPs) and heavy metals. Currently, there are no reports on the detection of MPs and MP-heavy metal synergies in RTCMs. In this study, we selected eight representative RTCMs to investigate the abundance, types, sizes, and polymers of MP and heavy metals and to assess the level of contamination of MPs and synergies between MPs and heavy metals in RTCMs. The abundance of MPs in different RTCM ranged from 20.83 to 43.65 items/g. The dominant type was fragment (95.43%), and the dominant particle size was < 0.5 mm (73.72%) in MPs. Polyurethane (PU) (29.21%) and acrylics (ACR 13.53%) were the dominant polymers of MP. MP polymers showed obvious correlations with type and particle size: PU was enriched in 0-50-mm and 100-300-mm fragments, whereas ethylene vinyl acetate and ACR were enriched in 0-30-mm fibers. The heavy metals arsenic (As), lead (Pb), and chromium (Cr) were found to be more susceptible to synergistic contamination with MPs in RTCMs compared to other heavy metals. The estimated daily intake (EDI) of the MPs and heavy metals for RG (Rehmannia glutinosa) and RAY (Rhizoma atractylodis) were higher than others. The results showed that MP pollution is common in RTCMs and carries the potential risk of heavy metal or MP poisoning in humans who consume RTCMs.

Impact of microplastics on aquatic flora: Recent status, mechanisms of their toxicity and bioremediation strategies

The accumulation of microplastics (MPs) in aquatic environments has occurred pervasively. The MPs affect almost all the aquatic plants including the aquatic microorganisms, ultimately disturbing the food chain. Aquatic flora attracts MPs due to the formation of several chemical bonds and interactions, including hydrogen bonds, electrostatic, hydrophobic, and van der Waals. Consequently, they hinder plant growth when adsorbed to the plant surfaces. Moreover, the major metabolic processes, including photosynthesis, reproduction, and nutrient uptake, get affected due to the pore-filling of plant tissues and the blockage of sunlight. Subsequently, prolonged exposure to MPs inflicts excessive generation of reactive oxygen species (ROS), ultimately accelerating programmed cell death. However, it has been realized that bioremediation techniques, including phytoremediation, can effectively mitigate MPs pollution by adsorbing or accumulating MPs by 25-80% at the laboratory scale. In this connection, several microorganisms are vital in deteriorating MPs due to their ability to form biofilm over the MPs' surface. Additionally, the secretion of extracellular enzymes such as styrene monooxygenase, styrene oxide isomerase, phenylacetaldehyde dehydrogenase, PETase, etc., facilitates the degradation of MPs. Moreover, the inherent ability of plants to adsorb and accumulate MPs can be utilized to manage the MPs in aquatic ecosystems. However, there is a dearth of literature and comprehensive reviews highlighting the potential of bioremediation strategies. Therefore, apart from addressing the impact of MPs on aquatic flora, this article attempts to elucidate the physical and chemical basis of plant-plastic interaction and the potential strategies aquatic flora including microorganisms employ to mitigate plastic pollution.

Combined Impact of Canada Goldenrod Invasion and Soil Microplastic Contamination on Seed Germination and Root Development of Wheat: Evaluating the Legacy of Toxicity

The concurrent environmental challenges of invasive species and soil microplastic contamination increasingly affect agricultural ecosystems, yet their combined effects remain underexplored. This study investigates the interactive impact of the legacy effects of Canada goldenrod (Solidago canadensis L.) invasion and soil microplastic contamination on wheat (Triticum aestivum L.) seed germination and root development. We measured wheat seed germination and root growth parameters by utilizing a controlled potted experiment with four treatments (control, S. canadensis legacy, microplastics, and combined treatment). The results revealed that the legacy effects of S. canadensis and microplastic contamination affected wheat seed germination. The effects of different treatments on wheat seedling properties generally followed an "individual treatment enhances, and combined treatment suppresses" pattern, except for root biomass. Specifically, the individual treatment promoted wheat seedling development. However, combined treatment significantly suppressed root development, decreasing total root length and surface area by 23.85% and 31.86%, respectively. These findings demonstrate that while individual treatments may promote root development, their combined effects are detrimental, indicating a complex interaction between these two environmental stressors. The study highlights the need for integrated soil management strategies to mitigate the combined impacts of invasive species and microplastic contamination on crop productivity and ecosystem health.

Impact of polystyrene nanoplastics on physiology, nutrient uptake, and root system architecture of aeroponically grown citrus plants

The widespread presence of plastic pollution has become a challenge for both aquatic and terrestrial plants. Notably, nanoplastics (NPs) have been found to enter the root tissues and translocate to different organs of plants; however, most previous studies were performed using crop or vegetable seedlings, and the extent NPs accumulation in fruit tree plants, particularly citrus, and their impacts remains unclear. This study was designed to fill this gap by determining the uptake and accumulation of green, fluorescent polystyrene nanoplastics (PS-NPs) of two different sizes (20 nm and 50 nm in diameter) in citrus rootstock ('US-942') in an aeroponic system and their impact on plant growth and physiological functions, nutrient uptake, and root system architectural and anatomical traits. The 20 nm PS-NPs negatively impacted the root system architecture (total root length, root surface area, number of root forks) and nutrient contents (N, P, K, Mg, S, B, Fe, Cu, Mn) at both 15 and 30 days after treatment; however, no significant differences were recorded for growth and physiological parameters. Microscopic analysis of roots revealed that under both the PS-NPs treatments, root apoplastic barriers were fully developed near the root tips. Furthermore, PS-NPs are predominantly adhered to the root surface, and no signs of uptake and translocation were recorded in root sections. However, alterations to the external root cell layers were observed. This research sheds light on the impact of PS-NPs on plant roots and their physiology and contributes to a better understanding of these emerging pollutants on tree crop horticulture.

Responses of microbial communities to the addition of different types of microplastics in agricultural soils

A 90-day soil incubation study was performed to investigate impacts of four types (PE, PP, PVC and PET) of microplastics (MPs) on the physicochemical properties, nutrient contents, enzyme activities, and microbial community structure and diversity of agricultural soils. Effects of the four microplastic types and addition ratios on the microbiology of the agricultural soils were significant. With the addition of MPs, there was a positive correlation between physicochemical properties, nutrients (AN, AP, AK) and enzyme activities (CAT, Urease, ACP, SUC), which were all decreased to some extent. Overall PE and PVC surfaces were the roughest and had the greatest impact on soil physicochemical properties, nutrients and enzyme activities. The changes in soil microbial α-diversity were not significant (P > 0.05), but, PP and PVC led to an increase in community diversity and abundance. Clearly, the four types of the MPs reduced the physicochemical properties, nutrient content, enzyme activity and microbial community, and thus significantly affected the microbiology of the farmland soils.

Polyvinyl chloride microplastics and drought co-exposure alter rice growth by affecting metabolomics and proteomics

Microplastics, interacting with drought stress, have become threat to crops by altering soil environment. Currently, the effect of combined microplastic and drought stress on crop growth remain poorly understood. In this work, the mechanism of multi-stress responses was investigated under the exposure of polvinylchloride microplastic (PV) and drought (D) individually and in combination (DPV) on rice varieties Hanyou73 and Q280 through proteomics and metabolomic analysis. All treatments negatively affect chlorophyll content, antioxidant enzyme activities, rice grain composition, metabolome and proteomic profiling of both rice varieties. Full rice grain yield was decreased under all treatments except PV treatment in which it was increased in both rice varieties. DPV treatment shows the lowest grain yield and more adverse effects on metabolome by affecting glycerophospholipid metabolism, tryptophan metabolism and alanine, aspartate and glutamate metabolism. Soluble sugar contents were decreased in H73 but in Q280 increased by 159 % under DPV and 123 % in PV treatment, compared to their control group. The results from metabolomics illustrate that glycerophospholipid metabolism is commonly altered in both rice types under all treatments. PV and drought alone and in combination induce extensive alterations in proteomics of rice leaves especially impacting proteins related to binding, translation and photosynthetic process. The results reveal that PV and DPV treatments highly distort the abundance of metabolites and proteins in both rice types, demonstrating that microplastic toxicity effects on rice plants become more severe when combined with drought stress.

Stress of soil moisture and temperature exacerbates the toxicity of tire wear particles to soil fauna: Tracking the role of additives through host microbiota

Tire wear particles (TWPs) are considered as an emerging threat to soil fauna. However, how TWP toxicity to soil fauna responds to the stress of soil moisture and temperature remains unclear. We assessed the toxicity of environmentally relevant TWPs to the soil model species Enchytraeus crypticus under three soil moisture and two temperature gradients. Typical thermoplastic polypropylene (PP) was selected for comparison. Results showed that compared with PP, TWPs exerted stronger toxicity, including decreasing the worm growth, survival and reproduction rates, disturbing the soil and worm gut microbiota, and leaching more diverse and higher contents of additives. Stress of soil moisture and temperature exacerbated TWP toxicity mainly through affecting the leaching and transformation of additives. Fourteen mediated additives significantly contributed to the shift of the gut microbiota under soil moisture and temperature stress, among which 1,3-diphenylguanidine, N,N'-bis(methylphenyl)-1,4-benzenediamine quinone, N-tert-butyl-2-benzothiazolesulfenamide, and 2-aminobenzothiazole were identified as the main drivers. In addition, this study provided the first clear evidence that increased soil moisture and temperature promoted the transformation of additives in the soil. Our study revealed the non-negligible aggravated toxicity of TWPs to soil fauna under stress of soil moisture and temperature, providing novel insights into the environmental behavior of additives.

Insights into photoaging behaviors and mechanisms of biodegradable and conventional microplastics in soil

Understanding the photoaging dynamics of biodegradable and conventional microplastics (MPs) is crucial due to their widespread environmental risks. However, studies on the photoaging behaviors of different MPs in soil ecosystems are limited. This study focused on two representative MPs, conventional polyethylene (PE) and biodegradable poly(butylene adipate-co-terephthalate) (PBAT), examining their photoaging processes in soil. The photoaging performance of these MPs was characterized using indicators like carbonyl index (CI), oxygen-carbon ratio (O/C), weight loss (WL), and water contact angle (CA). The entropy weight method (EWM) was employed to calculate a comprehensive aging index (CAI), quantitatively measuring overall photoaging. The results revealed that PBAT underwent significantly greater photoaging than PE, with the CAI of aged PBAT (0.88) being over 15 times higher than that of aged PE (0.06). Environmental persistent free radicals (EPFRs) were identified as key factors in MPs' photoaging. LC-MS/MS analysis revealed oxygen-containing byproducts and plastic additives, suggesting photodegradation pathways involving chain scission and oxidation. Density functional theory (DFT) highlighted differences in energy gaps and susceptibility to free radical attacks between PE and PBAT. This study not only compares photoaging behaviors but also introduces a novel method for evaluating MPs' aging, providing a basis for assessing ecological risks in soil.

Microplastic effects on carbon cycling in terrestrial soil ecosystems: Storage, formation, mineralization, and microbial mechanisms

Soil is the largest environmental reservoir of microplastics (MPs) on the earth. Incremental accumulation of MPs in the soil can cause significant changes in soil physicochemical and microbial traits, which may in turn interfere with soil biogeochemical processes such as carbon cycling. With published research regarding MPs impacts on soil carbon cycling growing rapidly, a systematic review summarizing the current knowledge and highlighting future research needs is warranted. As carbon-rich polymers, MPs can contribute to soil organic carbon (SOC) storage via degradation and leaching. MPs can also affect the humification of dissolved organic matters (DOM), consequently influencing the stability of SOC. Exposure to MPs can cause substantial impacts on the growth performance, litter decomposition, and root secretion of terrestrial plants as well as soil microbial carbon turnover, inducing changes in the formation of SOC. The presence of MPs has contrasting effects on the emissions of both CO2 and CH4 from the soil. The diverse effects of MPs on soil carbon metabolism could be partly attributed to the varying changes in soil microbial community structure, functional gene expression, and enzyme activity under MPs exposure. Further research is still highly needed to clarify the pathways of MPs impacts on soil carbon cycling and the driving biological and physicochemical factors behind these processes.

Feasibility assessment of biochar amendment for mitigating phytotoxicity of polyvinyl chloride micro/nano-plastics: A study based on lettuce pot experiments

Micro/nano-plastics (M/NPs) are pervasive in agricultural soils, and their detrimental effects on crops are increasingly evident. This ultimately results in reduced crop yields and quality, posing a great threat to global food security. Therefore, the urgent need to mitigate the phytotoxicity of M/NPs has become apparent. Biochar (BC), as an environmentally friendly soil amendment, plays a crucial role in modifying soil properties and boosting agricultural production levels. Its strong adsorption capacity enables it to effectively passivate soil pollutants and reduce their phytotoxicity. However, the effect of BC on the phytotoxicity of M/NPs in soil remains unknown. In this study, the feasibility of BC amendment for mitigating phytotoxicity of polyvinyl chloride M/NPs (PVC-M/NPs) was evaluated by conducting pot experiments. The results show that the application of 0.1% (w/w) PVC-M/NPs resulted in a 48.60% reduction in lettuce yield. This reduction can be attributed to the decreased soil microbial activity and soil cation exchange capacity (CEC), as well as the direct physical damage to lettuce roots caused by PVC-M/NPs. BC amendment improved soil quality, but had insignificant effect on lettuce biomass compared to the control (p > 0.05). In contrast, BC amendment at an appropriate concentration (0.5% and 2.5%, w/w) to soils contaminated with PVC-M/NPs resulted in a significant increase in lettuce yield (p < 0.01). Furthermore, BC was found to mitigate the oxidative stress of PVC-M/NPs on lettuce roots. This indicates that the BC amendment has the potential to mitigate the toxicity of PVC-M/NPs to lettuce. Improving soil quality and enhancing PVC-M/NPs adsorption are perceived as the influencing mechanisms of BC on the phytotoxicity of PVC-M/NPs. The findings suggest that it is feasible to mitigate the phytotoxicity of M/NPs through BC amendments.

Multifaceted effects of microplastics on soil-plant systems: Exploring the role of particle type and plant species

Microplastics have emerged as a global environmental concern, yet their impact on terrestrial environments, particularly agricultural soils, remains underexplored. Agricultural soils, due to intensive farming, may serve as significant sinks for microplastics. This study investigated the effects of different types of microplastics-polyester microfibers, polyethylene terephthalate microfragments, and polystyrene microspheres-on soil properties and radish growth, while a complementary experiment examined the impact of polyester microfibers on the growth of lettuce and Chinese cabbage. Through both horizontal and vertical comparisons, this research comprehensively evaluated the interactions between microplastic particles and plant species in soil-plant systems. The results showed that polyester microfibers significantly affected soil bulk density, with effects varying based on planting conditions (p < 0.01). Polyethylene terephthalate microfragments and polystyrene microspheres reduced the proportion of small soil macroaggregates under radish cultivation (p < 0.01). Additionally, polystyrene microspheres significantly altered the total organic carbon stock in radish-growing soil, potentially affecting the microclimate (p < 0.01). Interestingly, polyester microfibers promoted lettuce seed germination and significantly enhanced the root biomass of Chinese cabbage (p < 0.05). Overall, the environmental effects of microplastic exposure varied depending on the type of particle and plant species, suggesting that microplastics are not always harmful to soil-plant systems and may even offer benefits in certain scenarios. Given the crucial role of soil-plant systems in terrestrial ecosystems, and their direct connection to food safety, human health, and global change, further research should explore both the positive and negative impacts of microplastics on agricultural practices.

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.

Single and combined effect of polyethylene microplastics (virgin and naturally aged) and cadmium on pakchoi (Brassica rapa subsp. chinensis) under different growth stages

To protect agro-systems and food security, study on the effect of microplastics and heavy metals on edible plants is of great significance. Existing studies mostly used virgin microplastics to evaluate their effects on plants, effects of naturally aged microplastics and their combined effects with heavy metals are rarely explored. In this study, single and combined effect of polyethylene microplastics (PE, both virgin and naturally aged) and cadmium (Cd) on pakchoi under seedling and mature stages were analyzed from perspectives of growth inhibition, oxidative damage, nutrition content and soil enzyme activities. Results showed that inhibiting effects of naturally aged PE (PEa) on the growth of pakchoi were stronger than virgin PE (PEv), whereas co-contamination of PEa and Cd was less toxic than that of PEv and Cd. The co-contamination of PE and Cd could inhibit pakchoi dry biomass by over 85 %. Both single and combined contamination of PE and Cd promoted soil fluorescein diacetate hydrolase (FDA) activities, which were 1.11 to 2.04 times of that in control group. Soluble sugar contents under co-contamination of PEa and Cd were 14 % to 22 % higher than those in control group. PEa and PEv showed different effects on oxidative damage of pakchoi. Compared with PEv, catalase (CAT) activities were more sensitive with PEa, whereas PEa had lower effect on superoxide dismutase (SOD) activities. The response of pakchoi to PE and Cd changed with growth stage. Chlorophyll contents in pakchoi under seedling stage were generally higher than those under mature stage. For Cd contaminated soils, PE benefited pakchoi growth under seedling stage, i.e. antagonistic effect between Cd and PE but hindered their growth under mature stage, i.e. synergistic effect. The results unraveled here emphasized PE, especially PEa, could trigger negative effects on agro-systems, whereas PE could be beneficial for heavy metal contaminated agro-systems under specific situations.

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.

Effect of microplastics on the allelopathic effects of native and invasive plants on co-occurring invaders

Introduction

Microplastic pollution has emerged as a significant global change factor, with the potential to alter the biological, physicochemical properties of soil and to subsequently affect plant growth. Despite growing recognition of the impacts of microplastic pollution, the mechanisms by which microplastics modify plant leaf chemistry and influence allelopathic interactions among co-existing plant species remain unclear.

Methods

We used the native perennial forb Achyranthes bidentata and the invasive annual forb Amaranthus spinosus as focal species. We grew the two species with and without competition with each other. This setup was further combined with a treatment involving the addition of polyethylene (PE). We then testd the effects of aqueous extract on seed germination and seedling growth for five invasive and five native species. Subsequently, metabolomic analysis was conducted on the aqueous extracts, in which significant allelopathic effects were observed on test species.

Results and discussion

The presence of PE microplastics enhanced the biomass of both Achyranthes and Amaranthus under competitive and non-competitive growth conditions. Furthermore, PE microplastics were found to induce a negative allelopathic effect for the native plant Achyranthes on co-occurring plants, which appeared to be mediated through changes in leaf chemistry. Bisdemethoxycurcumin, ethylparaben, salicin 6'-sulfate and 5-hydroxy-3',4',7-trimethoxyflavone glucoside were proven important compounds for allelopathic enhancement. Overall, these results suggest that microplastic pollution has the capability to influence the co-existence of invasive and native plants by altering their allelopathic potential. This insight into the interactions between microplastics and plant allelopathy provides a novel perspective on how microplastic pollution could modify plant species interactions and ecosystem dynamics. Future studies could aim to answer how microplastics might affect plant root exudates and whether this process would mediate biological invasion.

Effects of microplastics concentration on plant root traits and biomass: Experiment and meta-analysis

The impact of microplastics (MPs) on plant growth, particularly root development, remains underexplored. To address this, a laboratory pot experiment and meta-analysis were conducted to assess how varying concentrations of MPs affect plant root growth. In pot experiments, the response of root traits to MPs differed by plant species. For F. arundinacea, a higher addition (1 % and 2 %) of polypropylene (PP) significantly increased the total length, surface area, volume, as well as fine root (<1 mm) surface area and volume. Partial least squares path modeling (PLS-PM) analysis showed that high concentrations of MPs affected plant root growth and plant root biomass by promoting fine root growth. Meta-analysis indicated that MPs increased shoot dry biomass by 32.7 % but reduced root dry biomass by 4.1 % and root length by 14.3 %. Higher concentrations (>0.5 %) of MPs significantly increased root length (35.2 %) and root dry biomass (6.3 %), whereas decreased shoot dry biomass (-8.6 %). Under the lower MPs concentration (<0.5 %), the root length and root dry biomass were decreased by 18.6 % and 11.1 %, respectively, and the shoot dry biomass was increased by 53.2 % compared with the treatment without MPs. The results emphasize the differences in performance between species for different MPs concentrations, implying that there may be future scope to select for species/varieties that are most resilient to the presence of MPs.

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

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

Above- and below-ground field study on the impacts of conventional and alternative mesoplastics on Hordeum vulgare growth and soil invertebrate communities

Plastic plays an important role in agriculture, but its use has become a concerning source of pollution. While new (bio)degradable, alternative plastics are being developed and used as mulching films, their ecological impacts, in particular under field conditions, are not well understood. Furthermore, there is a notable lack of knowledge on how plastic pollution affects soil invertebrate communities. Most existing studies primarily focus on microplastics, often neglecting the impacts of mesoplastics. This study therefore compared the separate effects of two conventional (polyethylene and polypropylene) and two alternative (polyethylene containing biodegradable additives and compostable polylactic acid) mesoplastic films on plant performance (biomass, seed yield) and soil mesofaunal assemblages in a field experiment. The mesoplastics were applied at 0.1% (w/w), prior to soil being planted with Hordeum vulgare (spring barley), which was grown to maturity, for 11 weeks. Generally, there were no measurable differences between the conventional and alternative plastic treatments, however, barley exposed to mesoplastics showed reduced biomass, seed yield, and chlorophyll content, along with increased oxidative stress. Soil fauna, particularly Collembola, had lower richness and abundance when exposed to both plastic types, but assemblage structure and composition remained unchanged after 11 weeks. This study is pivotal in highlighting that both conventional and alternative plastics can similarly affect plant health and soil ecosystems. The evidence provided is essential for refining future risk assessments of agricultural plastic pollution and underscores the urgent need for more sustainable practices and materials in agriculture.

Plastic pollution in agricultural landscapes: an overlooked threat to pollination, biocontrol and food security

Ecosystem services such as pollination and biocontrol may be severely affected by emerging nano/micro-plastics (NMP) pollution. Here, we synthesize the little-known effects of NMP on pollinators and biocontrol agents on the organismal, farm and landscape scale. Ingested NMP trigger organismal changes from gene expression, organ damage to behavior modifications. At the farm and landscape level, NMP will likely amplify synergistic effects with other threats such as pathogens, and may alter floral resource distributions in high NMP concentration areas. Understanding exposure pathways of NMP on pollinators and biocontrol agents is critical to evaluate future risks for agricultural ecosystems and food security.

Microplastic-contamination can reshape plant community by affecting soil properties

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

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

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

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

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

Lower concentration polyethylene microplastics can influence free-floating macrophyte interactions by combined effects of many weak interactions: A nonnegligible ecological impact

Microplastics (MPs) are ubiquitous in freshwater ecosystems and their accumulation has been considered an emerging threat. Early research on the effects of MPs on macrophytes primarily focused on the toxicological impacts on individual macrophytes, with several studies suggesting that lower concentrations of MPs have little impact on macrophytes. However, the ecological implications of lower MP concentrations on macrophyte communities remain largely unexplored. Here, we experimented to assess the effects of lower concentrations including 25 mg/L, 50 mg/L, 75 mg/L, and 100 mg/L of polyethylene (PE) microplastics on Spirodela polyrhiza and Lemna minor, and their community. Our results also indicated that PE concentrations below 100 mg/L had no significant effect on relative growth rate, specific leaf area, Chlorophyll a, Chlorophyll b, Chlorophyll a + b, carotenoid, malondialdehyde (MDA), catalase, and soluble sugar of monocultural S. polyrhiza. However, a lower concentration of PE significantly decreased the MDA of monocultural L. minor and significantly affected the comprehensive index of S. polyrhiza. These findings suggested that lower concentrations of PE can influence interactions between macrophytes maybe due to the cumulative effects of many weak interactions. Additionally, our study showed that 75 mg/L and 100 mg/L PE additions decreased the competitive balance index value of two macrophytes under mixed-culture condition. This result implied that the ecological influence of lower concentration MPs on macrophytes may manifest at the community level rather than at the population level, due to species-specific responses and varying degrees of sensitivity of macrophytes to PE concentrations. Thus, our study emphasizes the need to closely monitor the ecological consequences of emerging contaminants such as MPs accumulation on macrophyte communities, rather than focusing solely on the morphology and physiology of individual macrophytes.

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

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

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.

Nitrogen supply neutralizes the nanoplastic-plant interaction in a coastal wetland

The presence of nanoplastics posed a potential threat to coastal saline-alkaline wetlands where nitrogen (N) fertilizer is being implemented as an important ecological restoration measure. Notwithstanding, the effects of N inputs on plant community in polypropylene-nanoplastics (PP-NPs) coexistence environments are largely unknown. To address this, we investigated the effects of PP-NPs addition alone or combined N supply on community aboveground biomass, morphological traits, diversity, composition, niche differentiation, interspecific interactions, and assembly. Our results showed that the PP-NPs addition alone reduced community aboveground biomass and morphological traits. However, the addition of high concentration (0.5%) PP-NPs alone favored community α-diversity and reduced community stability, which could be weakened through combined N supply. Overall, the effect of PP-NPs addition alone on plant community composition was greater than that of combined N supply. We also demonstrated PP-NPs addition alone and combined N supply reduced the niche breadth of the plant community and affected the niche overlap of dominant species. In the assembly of plant communities, stochastic processes played a dominant role. We conclude that N fertilization can amend the terrestrial nanoplastics pollution, thus mitigating the effects of PP-NPs on the plant community.

The masking phenomenon of microplastics additives on oxidative stress responses in freshwater food chains

The variability and intrinsic mechanisms of oxidative stress induced by microplastics at different trophic levels in freshwater food chains are not well understood. To comprehensively assess the oxidative stress induced by polystyrene microplastics (PS-MPs) in freshwater food chains, the present study first quantified the oxidative stress induced by PS-MPs in organisms at different trophic levels using factorial experimental design and molecular dynamics methods. Then focuses on analyzing the variability of these responses across different trophic levels using mathematical statistical analysis. Notably, higher trophic level organisms exhibit diminished responses under PS-MPs exposure. Furthermore, the coexistence of multiple additives was found to mask these responses, with antioxidant plastic additives significantly influencing oxidative stress responses. Mechanism analysis using computational chemistry simulation determines that protein structure and amino acid characteristics are key factors driving PS-MPs induced oxidative stress variation in freshwater organisms at different nutrient levels. Increased hydrophobic additives induce protein helicalization and amino acid residue aggregation. This study systematically reveals the variability of biological oxidative stress response under different nutrient levels, emphasizing the pivotal role of chemical additives. Overall, this study offers crucial insights into PS-MPs' impact on oxidative stress responses in freshwater ecosystems, informing future environmental risk assessment.

The promoting effects of soil microplastics on alien plant invasion depend on microplastic shape and concentration

Both alien plant invasions and soil microplastic pollution have become a concerning threat for terrestrial ecosystems, with consequences on the human well-being. However, our current knowledge of microplastic effects on the successful invasion of plants remains limited, despite numerous studies demonstrating the direct and indirect impacts of microplastics on plant performance. To address this knowledge gap, we conducted a greenhouse experiment involving the mixtures of soil and low-density polyethylene (LDPE) microplastic pellets and fragments at the concentrations of 0, 0.5 % and 2.0 %. Additionally, we included Solidago decurrens (native plant) and S. canadensis (alien invasive plant) as the target plants. Each pot contained an individual of either species, after six-month cultivation, plant biomass and antioxidant enzymes, as well as soil properties including soil moisture, pH, available nutrient, and microbial biomass were measured. Our results indicated that microplastic effects on soil properties and plant growth indices depended on the Solidago species, microplastic shapes and concentrations. For example, microplastics exerted positive effects on soil moisture of the soil with native species but negative effects with invasive species, which were impacted by microplastic shapes and concentrations, respectively. Microplastics significantly impacted catalase (P < 0.05) and superoxide dismutase (P < 0.01), aboveground biomass (P < 0.01), and belowground/aboveground biomass (P < 0.01) of the native species depending on microplastic shapes, but no significant effects on those of the invasive species. Furthermore, microplastics effects on soil properties, nutrient, nutrient ratio, and plant antioxidant enzyme activities contributed to plant biomass differently among these two species. These results suggested that the microplastics exerted a more pronounced impact on native Solidago plants than the invasive ones. This implies that the alien invasive species displays greater resistance to microplastic pollution, potentially promoting their invasion. Overall, our study contributes to a better understanding of the promoting effects of microplastic pollution on plant invasion.

Microplastics/nanoplastics in porous media: Key factors controlling their transport and retention behaviors

Till now, microplastics/nano-plastics(M/NPs) have received a lot of attention as emerging contaminant. As a typical but complex porous medium, soil is not only a large reservoir of M/NPs but also a gateway for M/NPs to enter groundwater. Therefore, the review of the factors controlling the transport behavior of M/NPs in porous media can provide important guidance for the risk assessment of M/NPs in soil and groundwater. In this study, the key factors controlling the transport behavior of M/NPs in porous media are systematically divided into three groups: (1) nature of M/NPs affecting M/NPs transport in porous media, (2) nature of flow affecting M/NPs transport in porous media, (3) nature of porous media affecting M/NPs transport. In each group, the specific control factors for M/NPs transport in porous media are discussed in detail. In addition to the above factors, some substances (colloids or pollutants) present in natural porous media (such as soil or sediments) will co-transport with M/NPs and affect its mobility. According to the different properties of co-transported substances, the mechanism of promoting or inhibiting the migration behavior of M/NPs in porous media was discussed. Finally, the limitations and future research directions of M/NPs transport in porous media are pointed out. This review can provide a useful reference for predicting the transport of M/NPs in natural porous media.

Microplastics and cadmium affect invasion success by altering complementarity and selection effects in native community

The diversity-invasibility hypothesis predicts that native plant communities with high biodiversity should be more resistant to invasion than low biodiversity communities. However, observational studies have found that there is often a positive relationship between native community diversity and invasibility. Pollutants were not tested for their potential to cause this positive relationship. Here, we established native communities with three levels of diversity (1, 2 and 4 species) and introduced an invasive plant [Symphyotrichum subulatum (Michx.) G. L. Nesom] to test the effects of different pollutant treatments (i.e., unpolluted control, microplastics (MPs) alone, cadmium (Cd) alone, and their combination) on the relationship between native community diversity and community invasibility. Our results indicate that different MPs and Cd treatments altered the invasibility of native communities, but this effect may depend on the type of pollutant. MPs single treatment reduced invasion success, and the degree of reduction increased with increasing native community diversity (Diversity 2: - 14.1 %; Diversity 4: - 63.1 %). Cd single treatment increased the aboveground biomass of invasive plants (+ 40.2 %) and invasion success. The presence of MPs inhibited the contribution of Cd to invasion success. Furthermore, we found that the complementarity and selection effects of the native community were negatively correlated with invasion success, and their relative contributions to invasion success also depended on the pollutant type. We found new evidence of how pollutants affect the relationship between native community diversity and habitat invasibility, which provides new perspectives for understanding and managing biological invasions in the context of environmental pollution. This may contribute to promoting the conservation of biodiversity, especially in ecologically sensitive and polluted areas.

Arbuscular Mycorrhizal Fungus Alleviates Charged Nanoplastic Stress in Host Plants via Enhanced Defense-Related Gene Expressions and Hyphal Capture

Contamination of small-sized plastics is recognized as a factor of global change. Nanoplastics (NPs) can readily enter organisms and pose significant ecological risks. Arbuscular mycorrhizal (AM) fungi are the most ubiquitous and impactful plant symbiotic fungi, regulating essential ecological functions. Here, we first found that an AM fungus, Rhizophagus irregularis, increased lettuce shoot biomass by 25-100% when exposed to positively and negatively charged NPs vs control, although it did not increase that grown without NPs. The stress alleviation was attributed to the upregulation of gene expressions involving phytohormone signaling, cell wall metabolism, and oxidant scavenging. Using a root organ-fungus axenic growth system treated with fluorescence-labeled NPs, we subsequently revealed that the hyphae captured NPs and further delivered them to roots. NPs were observed at the hyphal cell walls, membranes, and spore walls. NPs mediated by the hyphae were localized at the root epidermis, cortex, and stele. Hyphal exudates aggregated positively charged NPs, thereby reducing their uptake due to NP aggregate formation (up to 5000 nm). This work demonstrates the critical roles of AM fungus in regulating NP behaviors and provides a potential strategy for NP risk mitigation in terrestrial ecosystems. Consequent NP-induced ecological impacts due to the affected AM fungi require further attention.

Global Responses of Soil Carbon Dynamics to Microplastic Exposure: A Data Synthesis of Laboratory Studies

Microplastics (MPs) contamination presents a significant global environmental challenge, with its potential to influence soil carbon (C) dynamics being a crucial aspect for understanding soil C changes and global C cycling. This meta-analysis synthesizes data from 110 peer-reviewed publications to elucidate the directional, magnitude, and driving effects of MPs exposure on soil C dynamics globally. We evaluated the impacts of MPs characteristics (including type, biodegradability, size, and concentration), soil properties (initial pH and soil organic C [SOC]), and experimental conditions (such as duration and plant presence) on various soil C components. Key findings included the significant promotion of SOC, dissolved organic C, microbial biomass C, and root biomass following MPs addition to soils, while the net photosynthetic rate was reduced. No significant effects were observed on soil respiration and shoot biomass. The study highlights that the MPs concentration, along with other MPs properties and soil attributes, critically influences soil C responses. Our results demonstrate that both the nature of MPs and the soil environment interact to shape the effects on soil C cycling, providing comprehensive insights and guiding strategies for mitigating the environmental impact of MPs.

Microplastics and nanoplastics: Source, behavior, remediation, and multi-level environmental impact

Plastics introduced into the natural environment persist, degrade, and fragment into smaller particles due to various environmental factors. Microplastics (MPs) (ranging from 1 μm to 5 mm) and nanoplastics (NPs) (less than 1 μm) have emerged as pollutants posing a significant threat to all life forms on Earth. Easily ingested by living organisms, they lead to ongoing bioaccumulation and biomagnification. This review summarizes existing studies on the sources of MPs and NPs in various environments, highlighting their widespread presence in air, water, and soil. It primarily focuses on the sources, fate, degradation, fragmentation, transport, and ecotoxicity of MPs and NPs. The aim is to elucidate their harmful effects on marine organisms, soil biota, plants, mammals, and humans, thereby enhancing the understanding of the complex impacts of plastic particles on the environment. Additionally, this review highlights remediation technologies and global legislative and institutional measures for managing waste associated with MPs and NPs. It also shows that effectively combating plastic pollution requires the synergization of diverse management, monitoring strategies, and regulatory measures into a comprehensive policy framework.

The impacts of microplastics on the cycling of carbon and nitrogen in terrestrial soil ecosystems: Progress and prospects

As contaminants of emerging concern, microplastics (MPs) are ubiquitously present in almost all environmental compartments of the earth, with terrestrial soil ecosystems as the major sink for these contaminants. The accumulation of MPs in the soil can trigger a wide range of effects on soil physical, chemical, and microbial properties, which may in turn cause alterations in the biogeochemical processes of some key elements, such as carbon and nitrogen. Until recently, the effects of MPs on the cycling of carbon and nitrogen in terrestrial soil ecosystems have yet to be fully understood, which necessitates a review to summarize the current research progress and propose suggestions for future studies. The presence of MPs can affect the contents and forms of soil carbon and nitrogen nutrients (e.g., total and dissolved organic carbon, dissolved organic nitrogen, NH4+-N, and NO3--N) and the emissions of CH4, CO2, and N2O by altering soil microbial communities, functional gene expressions, and enzyme activities. Exposure to MPs can also affect plant growth and physiological processes, consequently influencing carbon fixation and nitrogen uptake. Specific effects of MPs on carbon and nitrogen cycling and the associated microbial parameters can vary considerably with MP properties (e.g., dose, polymer type, size, shape, and aging status) and soil types, while the mechanisms of interaction between MPs and soil microbes remain unclear. More comprehensive studies are needed to narrow the current knowledge gaps.

Uptake of microplastics and impacts on plant traits of savoy cabbage

Anthropogenic influences such as plastic pollution are causing serious environmental problems. While effects of microplastics on marine organisms are well studied, less is known about effects of plastic particles on terrestrial organisms such as plants. We investigated the effects of microplastic particles on different growth and metabolic traits of savoy cabbage (Brassica oleracea var. sabauda). Sections of seedlings exposed to polystyrene particles were analysed by coherent Raman scattering microscopy. These analyses revealed an uptake of particles in a size range of 0.5 µm to 2.0 µm into cells of the hypocotyl. Furthermore, plants were grown in substrate amended with polyethylene and polystyrene particles of different sizes (s1: 200-500 µm; s2: 100-200 µm; s3: 20-100 µm; s4: < 100 µm, with most particles < 20 µm; s5: < 20 µm) and in different concentrations (c1 = 0.1%, c2 = 0.01%, c3 = 0.001%). After several weeks, shoot and root biomass were harvested. Leaves were analysed for their carbon to nitrogen ratio, while amino acid and glucosinolate composition were measured using high performance liquid chromatography. Plastic type, particle size and concentration showed distinct effects on certain plant traits. Shoot biomass was interactively influenced by size and concentration of polyethylene, while root biomass was not modified by any of the plastic exposure treatments. Likewise, the composition and total concentrations of leaf amino acids were not affected, but the leucine concentration was significantly increased in several of the plastic-exposed plants. Glucosinolates were also slightly altered, depending on the particle size. Some of the observed effects may be independent of plastic uptake, as larger particles were not taken up but still could affect plant traits. For example, in the rhizosphere plastic particles may increase the water holding capacity of the soil, impacting some of the plant traits. In summary, this study shows how important the plastic type, particle size and concentration are for the uptake of microplastics and their effects on plant traits, which may have important implications for crops, but also for ecosystems.

Occurrence, transport, and toxicity of microplastics in tropical food chains: perspectives view and way forward

Microplastics, which have a diameter of less than 5 mm, are becoming an increasingly prevalent contaminant in terrestrial and aquatic ecosystems due to the dramatic increase in plastic production to 390.7 million tonnes in 2021. Among all the plastics produced since 1950, nearly 80% ended up in the environment or landfills and eventually reached the oceans. Currently, 82-358 trillion plastic particles, equivalent to 1.1-4.9 million tonnes by weight, are floating on the ocean's surface. The interactions between microorganisms and microplastics have led to the transportation of other associated pollutants to higher trophic levels of the food chain, where microplastics eventually reach plants, animals, and top predators. This review paper focuses on the interactions and origins of microplastics in diverse environmental compartments that involve terrestrial and aquatic food chains. The present review study also critically discusses the toxicity potential of microplastics in the food chain. This systematic review critically identified 206 publications from 2010 to 2022, specifically reported on microplastic transport and ecotoxicological impact in aquatic and terrestrial food chains. Based on the ScienceDirect database, the total number of studies with "microplastic" as the keyword in their title increased from 75 to 4813 between 2010 and 2022. Furthermore, various contaminants are discussed, including how microplastics act as a vector to reach organisms after ingestion. This review paper would provide useful perspectives in comprehending the possible effects of microplastics and associated contaminants from primary producers to the highest trophic level (i.e. human health).

Microplastics could alter invasive plant community performance and the dominance of Amaranthus palmeri

The increase in alien plant invasions poses a major threat to global biodiversity and ecosystem stability. However, the presence of microplastics (MPs) as an environmental stressor could impact the interactions between invasive and native species in an invasive plant community. Nevertheless, the community alterations and underlying mechanisms resulting from these interactions remain unclear. Herein, we systematically investigated the impacts of polyethylene (PE) and polypropylene (PP) on invasive plant communities invaded by Amaranthus palmeri through soil seed bank. The results illustrated that MPs markedly declined community height and biomass, and altered community structure, low-dose MPs could prominently increase community invasion resistance, but reduced community stability. The niche width and niche overlap of A. palmeri and S. viridis declined when exposed to high-dose MPs, but MPs elicited a significant rise in the niche width of S. salsa. PP had the potential to reduce the diversity of invasive plant community. Structural equation model revealed that PP addition could change soil total phosphorus content, thereby leading to a reduction of the community stability. Our study helps to fill the knowledge gap regarding the effects of MPs on invasive plant communities and provide new perspectives for invasive plant management.

Optimization of microplastic removal based on the complementarity of constructed wetland and microalgal-based system

As one of the emblematic emerging contaminants, microplastics (MPs) have aroused great public concern. Nevertheless, the global community still insufficiently acknowledges the ecological health risks and resolution strategies of MP pollution. As the nature-based biotechnologies, the constructed wetland (CW) and microalgal-based system (MBS) have been applied in exploring the removal of MPs recently. This review separately presents the removal research (mechanism, interactions, implications, and technical defects) of MPs by a single method of CWs or MBS. But one thing with certitude is that the exclusive usage of these techniques to combat MPs has non-negligible and formidable challenges. The negative impacts of MP accumulation on CWs involve toxicity to macrophytes, substrates blocking, and nitrogen-removing performance inhibition. While MPs restrict MBS practical application by making troubles for separation difficulties of microalgal-based aggregations from effluent. Hence the combined strategy of microalgal-assisted CWs is proposed based on the complementarity of biotechnologies, in an attempt to expand the removing size range of MPs, create more biodegradable conditions and improve the effluent quality. Our work evaluates and forecasts the potential of integrating combination for strengthening micro-polluted wastewater treatment, completing the synergistic removal of MP-based co-pollutants and achieving long-term stability and sustainability, which is expected to provide new insights into MP pollution regulation and control.

Microplastics as carriers of toxic pollutants: Source, transport, and toxicological effects

Microplastic pollution has emerged as a new environmental concern due to our reliance on plastic. Recent years have seen an upward trend in scholarly interest in the topic of microplastics carrying contaminants; however, the available review studies have largely focused on specific aspects of this issue, such as sorption, transport, and toxicological effects. Consequently, this review synthesizes the state-of-the-art knowledge on these topics by presenting key findings to guide better policy action toward microplastic management. Microplastics have been reported to absorb pollutants such as persistent organic pollutants, heavy metals, and antibiotics, leading to their bioaccumulation in marine and terrestrial ecosystems. Hydrophobic interactions are found to be the predominant sorption mechanism, especially for organic pollutants, although electrostatic forces, van der Waals forces, hydrogen bonding, and pi-pi interactions are also noteworthy. This review reveals that physicochemical properties of microplastics, such as size, structure, and functional groups, and environmental compartment properties, such as pH, temperature, and salinity, influence the sorption of pollutants by microplastic. It has been found that microplastics influence the growth and metabolism of organisms. Inadequate methods for collection and analysis of environmental samples, lack of replication of real-world settings in laboratories, and a lack of understanding of the sorption mechanism and toxicity of microplastics impede current microplastic research. Therefore, future research should focus on filling in these knowledge gaps.

Microplastic contamination in the agricultural soil-mitigation strategies, heavy metals contamination, and impact on human health: a review

Microplastic pollution has emerged as a critical global environmental issue due to its widespread distribution, persistence, and potential adverse effects on ecosystems and human health. Although research on microplastic pollution in aquatic environments has gained significant attention. However, a limited literature has summarized the impacts of microplastic pollution the agricultural land and human health. Therefore, In the current review, we have discussed how microplastic(s) affect the microorganisms by ingesting the microplastic present in the soil, alternatively affecting the belowground biotic and abiotic components, which further elucidates the negative effects on the above-ground properties of the crops. In addition, the consumption of these crops in the food chain revealed a potential risk to human health throughout the food chain. Moreover, microplastic pollution has the potential to induce a negative impact on agricultural production and food security by altering the physiochemical properties of the soil, microbial population, nutrient cycling, and plant growth and development. Therefore, we discussed in detail the potential hazards caused by microplastic contamination in the soil and through the consumption of food and water by humans in daily intake. Furthermore, further study is urgently required to comprehend how microplastic pollution negatively affects terrestrial ecosystems, particularly agroecosystems which drastically reduces the productivity of the crops. Our review highlights the urgent need for greater awareness, policy interventions, and technological solutions to address the emerging threat of microplastic pollution in soil and plant systems and mitigation strategies to overcome its potential impacts on human health. Based on existing studies, we have pointed out the research gaps and proposed different directions for future research.