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

Microplastics in Agricultural Soils: Sources, Fate, and Interactions with Other Contaminants

Microplastics (MPs) are recognized as emerging soil contaminants. However, the potential risks of MPs to agroecosystems have not been fully revealed, especially the compound toxic effects of MPs with co-existing organic or inorganic pollutants (OPs/IPs) in agricultural fields. In this study, we quantified the contributions of different agronomic practices to the sources of MPs in soil and highlighted the important influences of long-term tillage and fertilization on the migration and aging of MPs in agricultural fields. In addition, the antagonistic and synergistic interactions between MPs and OPs/IPs in soil were explored. We emphasized that the degree of adsorption of MPs and soil particles to OPs/IPs is a key determinant of the co-toxicity of those contaminants in soil. Finally, several directions for future research are proposed, and these knowledge gaps provide an important basis for understanding the contamination process of MPs in agricultural soils.

Application of omics technology in ecotoxicology of arthropod in farmland

Arthropods, abundant in farmland, have unique biological traits that make them valuable for studying the ecotoxicological impacts of pollutants. Recent advancements in multi-omics technologies have enhanced their use in assessing pollution risks and understanding toxicity mechanisms. This article reviews recent developments in applying omics technologies-genomics, transcriptomics, proteomics, metabolomics, and meta-omics-to ecotoxicological research on farmland arthropods. Agricultural arthropods manage genes and proteins, such as metallothioneins, antioxidant enzyme systems, heat shock proteins, cytochrome P450, carboxylesterases, and glutathione S-transferases, for detoxification and antioxidant purposes. They adjust amino acid, sugar, and lipid metabolism to counteract pollutant-induced energy drain and modify gut microbiota to aid in detoxification. This study advocates for enhanced analysis of compound pollution and emerging pollutants using multi-omics, especially meta-omics, to clarify the toxicological mechanisms underlying arthropod responses to these pollutants. Furthermore, it underscores the urgent need for subsequent gene function mining and validation to support biological control strategies and promote sustainable agricultural practices. The findings of this research provide significant insights into the toxicological impacts and mechanisms of pollutants within farmland ecosystems, thereby contributing to the preservation of arthropod diversity.

Insights Into the Efficiency and Health Impacts of Emerging Microplastic Bioremediation Approaches

The pollution caused by microplastics (MPs) is a global environmental and health concern. These plastic particles disrupt food chains and pose health risks to organisms, including humans. From a total of 827 studies, synthetic textiles (35%) and tires (28%) are the primary sources of MPs, with fibers being the most common shape (60%). MPs were detected in feces (44% of studies), lungs (35%), and blood (17%), indicating widespread contamination and potential health impacts. Bioremediation is a promising and sustainable method for mitigating MP pollution, as it uses microorganisms and plants to break down or convert MPs into less hazardous substances. However, it is important to understand and address the potential unintended consequences of bioremediation methods on the environment and human health. This scoping literature review examines the efficiency of currently emerging approaches for microplastic bioremediation, their strengths and weaknesses, and their potential impacts on the environment and human health. Highly effective methods such as mycoremediation, soil microbes for enhanced biodegradation, and phytoextraction were identified, but they pose high toxicity risks. Moderately effective methods include plant-assisted remediation, rhizosphere degradation, phytodegradation, and biodegradation, with effectiveness rates between 50% and 65% and moderate toxicity risks.

Assessing microplastics, per- and polyfluoroalkyl substances (PFAS), and other contaminants of global concern in wadable agricultural streams in Iowa

Microplastics, per- and polyfluoroalkyl substances (PFAS), antibiotic resistance genes (ARGs), pharmaceuticals and personal care products (PPCPs), and pesticides may lead to unintended environmental contamination through many pathways in multiple matrices. This statewide, multi-matrix study of contaminants of global concern (CGCs) in agricultural streams across Iowa (United States) is the first to examine multiple CGCs in water, bed sediment, and fish to understand their occurrence in small streams located in regions of intense agriculture activity. Iowa plays a pivotal role in agriculture, with more than 85% of Iowa's landscape devoted to agriculture, making it an ideal location for determining the prevalence of CGCs to provide critical baseline exposure data. Fifteen sites were sampled across a range of predominant land uses (e.g., poultry, swine); all sites had detections of microplastics in all matrices. Concentrations of PFAS varied but were detected in water and sediment; all fish had detections of perfluorooctanesulfonate (PFOS), a type of PFAS. More than 50% of water and bed sediment samples had detections of ARGs. The most frequently detected PPCP was metformin. No sites had a cumulative exposure activity ratio greater than 1.0 for chemical exposures; 13 sites were above the 0.001 precautionary threshold. Toxicity quotients calculated using Aquatic Life Benchmarks were below the 0.1 moderate risk threshold for chemical exposures for all but one site. For fish, all sites exceeded the moderate and high-risk thresholds proposed for microplastic particles for food dilution (both chronic and acute exposures) and all sites exceeded the microplastic moderate threshold proposed for chronic tissue translocation, and two sites exceeded the threshold for acute tissue translocation.

Soil nitrogen deficiency aggravated the aging of biodegradable microplastics in paddy soil under the input of organic substances with contrasting C/N ratios

The application of organic substances to the agricultural field has effectively enhanced soil nutrient levels and crop yields. Biodegradable microplastics (bio-MPs), a pervasive emerging contaminant, may potentially impact the soil ecosystem through their aging process. Here, a 150-day dark incubation experiment was conducted to elucidate the disparities in the aging process of polylactic acid bio-MPs (PLA-MPs) in soils with contrasting C/N ratios of organic substances, as the mechanisms underlying this process remain unclear. The study found that PLA-MPs resulted in an increase in soil pH, nutrient levels, and organic carbon content in soil-straw system. Additionally, PLA-MPs significantly influenced bacterial community composition and microbial metabolic activity in soil-straw system. Notably, more pronounced aging features of PLA-MPs was observed in soil-straw system (lower soil nitrogen environment) compared to soil-fertilizer system (higher soil nitrogen environment). Under lower soil nitrogen conditions, microorganisms may accelerate the aging process of PLA-MPs due to their preference for readily available energy sources; conversely, under higher soil nitrogen conditions, the aging of PLA-MPs may be decelerated as microorganisms preferentially utilize substances with easily accessible energy sources. Our findings provide valuable insights into the interaction between PLA-MPs and soil amended with the organic substances of contrasting C/N ratios.

Effects of polyamide microplastics with different particle sizes on the development of silkworm Bombyx mori (Lepidoptera: Bombycidae) and its progeny: A study based on the age-stage, two-sex life table

Influenced by human activities, microplastics (MPs) are widely distributed in terrestrial ecosystems. However, their ecotoxicity remains unclear. Therefore, we assessed the ecotoxicity of polyamide microplastics (PA-MPs) by investigating their toxic effects on the model insect, the silkworms Bombyx mori (Lepidoptera: Bombycidae). In this study, fifth-instar silkworm larvae were fed mulberry leaves treated with PA-MPs for 120 hours, but no changes in mortality rates were observed. However, the body weight, pupal weight, cocoon weight, egg laying amount, and cocoon shell weight in F0 generation silkworms were significantly reduced. This indicates that PA-MPs have sublethal effects on silkworms. To further investigate the effects of PA-MPs on the offspring of silkworms, we applied the age-stage, two-sex life table analysis. We found that in the PA-MPs treatment group, the duration of the larval and pupal stages of F1 generation silkworms was significantly prolonged, while the lifespan of the adults and total longevity were shortened. Meanwhile, the life history parameters (sxj, exj, lx, fxj, lxmx, and vxj values) and population parameters (R0, λ, r, and T) of F1 generation silkworms in the PA-MPs treatment group were also lower than control. This indicates that PA-MPs have transgenerational effects, affecting the growth, development, and reproduction of F1 generation silkworms. Our research findings demonstrate the sublethal and transgenerational effects of PA-MPs on silkworms, providing evidence for their ecotoxicity.

Microplastic-Induced Alterations in Soil Aggregate-Associated Carbon Stabilization Pathways: Evidence from δ13C Signature Analysis

Microplastics (MPs) are known to affect soil carbon stability in a numerous ways. However, the mechanisms by which they alter the carbon stability within soil aggregates remain unclear . Herein, a one-year field experiment was conducted in an arid agricultural region employing stable isotope techniques to evaluate the soil organic carbon flow in the presence of both persistent (PE, PVC) and biodegradable (PLA, PHA) MPs. PE and PVC reduced the stability of soil aggregates, while PLA and PHA maintained it. Additionally, organic carbon content increased in microaggregates but decreased in small macroaggregates for PE and PVC treatments. By contrast, treatment with PLA and PHA enhanced organic carbon content across aggregates. The δ13C values of PE- and PVC-treated aggregates ranged from -25.34 to -20.85‰, while those of PLA and PHA ranged from -16.29 to -9.26‰. Notably, MPs altered the direction of carbon flow between aggregates, reduced carbon flux, and accelerated carbon emissions. RFP and PLS-PM analyses revealed that persistent MPs affected carbon flow primarily via abiotic factors, whereas biodegradable MPs influenced it via biotic factors. These findings provide insights into the mechanisms by which MPs impact aggregate-associated carbon, highlighting their effects on soil ecosystem services.

Toxicity Mechanisms of Microplastic and Its Effects on Ruminant Production: A Review

Plastic pollution has become one of the major environmental problems facing human beings in the world today. Plastic waste accumulated in the environment forms plastic particles of different sizes due to farming activities, climate change, ultraviolet light, microbial degradation, and animal chewing. The pollution caused by microplastics has become a major environmental problem in recent years, and it is also a research hotspot in the field of ecological environment. More and more studies have found that ruminants are exposed to microplastics for a long time, which seriously threaten their healthy growth. This paper introduces the current situation of plastic pollution; the properties of microplastics and their effects on the ecological environment, human beings, and animals; summarizes the types and toxicity mechanisms of microplastics; and concludes the main ways that microplastics enter ruminants and their harm to them. In addition, the shortcomings and future development of microplastics in ruminants research are summarized and prospected to provide theoretical reference for the related research on alleviating the influence of microplastics on ruminant production.

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

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

Potential impacts of microplastic pollution on soil-water-plant dynamics

This study was designed to assess the potential impact of microplastic (MP) pollution on soil hydrology, specifically in retaining and releasing moisture. Herein, High-Density Polyethylene (HDPE) MP of different sizes (i.e., 0.5-1, 1-3, and 3-5 mm) and shapes (i.e., fiber, film, and fragment) were evaluated for their effects on water retention curve (WRC) of sandy loam soil, chosen for its agricultural relevance and widespread environmental presence of HDPE. Nine contamination scenarios were simulated with a low MP pollution rate, 0.01% w/w. Van Genuchten models were used to assess plant available water (PAW), wilting point (WP), and water holding capacity (WHC). Results showed that studied MP could significantly affect WRC and PAW mainly by changing WHC rather than WP and that this effect varied with MP shape and size. According to the results, fragment MP had the greatest impact on soil WHC by increasing 36.3%, followed by fibers and films by 19.8% and 15.7%. MP particles significantly increased WHC, while WP remained relatively unchanged. An observed trend indicated that the impact on WHC increased with the size of the MP particles. These findings emphasize the need to manage soil MP pollution to protect plant growth, agriculture, and water dynamics.

Novel insights related to soil microplastic abundance and vegetable microplastic contamination

Despite evidence of the uptake of soil microplastics (MPs) by crops, there is a paucity of knowledge regarding the contamination of vegetables in real-world environments with microplastics. This study establishes a correlation between the presence of microplastics in farmland and the concentration of microplastics in crops. The soil samples were found to contain Polyethylene (PE), polypropylene (PP), polystyrene (PS) and polyvinyl chloride (PVC). The proportions of PE and PP in the soil were considerable, with values ranging from 35 % to 70.6 % and 19.3 % to 50 %, respectively. The levels of PVC, PS and Polymethyl methacrylate (PMMA) in vegetables ranged from 3.64 to 17.37 μg g-1, 0.67 to 2.45 μg g-1 and 0.02 to 0.27 μg g-1, with Chinese cabbage exhibiting the highest concentration at 19.84 μg g-1. The highest level of PMMA was found in eggplant at 0.27 μg g-1. Vegetables sampled, including aubergine, lettuce and Chinese cabbage, contained more than two types of plastic. A correlation coefficient of 0.579 was observed between microplastics in vegetables and soil. This study provides insight into the contamination of environmental soils and different types of vegetables, and the data serve as a reference point for future studies.

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

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

Quantitative methodology for poly (butylene adipate-co-terephthalate) (PBAT) microplastic detection in soil and compost

With the increasing use of biodegradable plastics in agriculture and food packaging, it has become increasingly important to assess the effects of their fragmentation and mineralization in the environment (i.e., soil, compost). PBAT is a biodegradable polyester widely used in biodegradable mulch films that are intended to fragment and mineralize in soil. To study these effects, novel methodologies are needed to quantify PBAT microplastics in these diverse environments. This work seeks to answer whether gas chromatography mass spectrometry (GCMS) can be used as a tool to assess PBAT microplastics in soil. A method was developed that allows PBAT soil extraction by ultrasonication and GCMS quantification after a fatty acid methyl ester derivatization. To validate the method, an industrial compost degradation experiment was carried out to evidence the weight loss of PBAT film and quantify the micro- and nano-plastic generated from them. The presented method improved the existing resolution by, at least, one order of magnitude compared to reported methods. In conclusion, a novel, simple, affordable, and reproducible methodology for PBAT microplastic detection was developed improving the limits of detection and quantification. The method was tested on an industrial compost experiment, demonstrating the ability to trace the totality of the plastic over time, evidencing that PBAT is consumed in the industrial compost environment.

Emerging investigator series: open dumping and burning: an overlooked source of terrestrial microplastics in underserved communities

Open dumping and burning of solid waste are widely practiced in underserved communities lacking access to solid waste management facilities; however, the generation of microplastics from these sites has been overlooked. We report elevated concentrations of microplastics (MPs) in soil of three solid waste open dump and burn sites: a single-family site in Tuttle, Oklahoma, USA, and two community-wide sites in Crow Agency and Lodge Grass, Montana, USA. We extracted, quantified, and characterized MPs from two soil depths (0-9 cm and 9-18 cm). The average of abundance of particles found at community-wide sites three sites (18, 460 particles kg-1 soil) equals or exceeds reported concentrations from currently understood sources of MPs including biosolids application and other agricultural practices. Attenuated total reflectance Fourier transformed infrared (ATR-FTIR) identified polyethylene as the dominant polymer across all sites (46.2-84.8%). We also detected rayon (≤11.5%), polystyrene (up to 11.5%), polyethylene terephthalate (≤5.1), polyvinyl chloride (≤4.4%), polyester (≤3.1), and acrylic (≤2.2%). Burned MPs accounted for 76.3 to 96.9% of the MPs found in both community wide dumping sites. These results indicate that solid waste dumping and burning activities are a major source of thermally oxidized MPs for the surrounding terrestrial environment with potential to negatively affect underserved communities.

Micro-nanoscale polystyrene co-exposure impacts the uptake and translocation of arsenic and boscalid by lettuce (Lactuca sativa)

The influence of micro-nanoplastics (MNPs) on the fate and effects of other pollutants present in the environment is largely unknown. This study evaluated if the root exposure to MNPs (polystyrene, PS; 20 or 1000 nm) had an impact on the accumulation of arsenic and boscalid (As and Bos) in lettuce (Lactuca sativa). Under hydroponic conditions, plants were co-exposed to MNPs at 10 or 50 mg/L, and to 1 mg/L of each environmental pollutant (EP). For soil-like media, plants were exposed to MNPs at 50 and EPs at 10 mg/kg. Phytotoxicity was enhanced by PS under both growth conditions, particularly by nanoscale PS (nPS), although impacts were less in potting mix-grown plants. Nanoscale PS had a greater impact than microscale PS (μPS) on As fate; the As translocation factor from roots to the edible shoots was increased 3-fold in plants exposed to nPS (50 mg/L) and EPs. PS dose and size had a variable impact on Bos uptake and translocation. Fluorescent microscopy analysis of lettuce co-exposed to MNPs and EPs suggests that nPS is entering the roots and translocating to the leaves, while μPS mostly remains in the roots. Pyrolysis-GC/MS showed that in solid media, the presence of EPs significantly increased the translocation of nPS to lettuce shoots from 4.43 ± 0.53 to 46.6 ± 9.7 mg/kg, while the concentration of μPS in the shoots remained the same regardless of the presence of EPs (ranging between 13.2 ± 5.5 to 14.2 ± 4.1 mg/kg). These findings demonstrate that co-exposure of MNPs with other EPs can significantly impact co-contaminant accumulation and toxicity, presenting an unknown risk to humans and other receptors.

Microplastics stimulated soil bacterial alpha diversity and nitrogen cycle: A global hierarchical meta-analysis

Microplastics (MPs) pollution is recognized as a global emerging threat with serious potential impacts on ecosystems. Our meta-analysis was conducted based on 117 carefully selected publications, from which 2160 datasets were extracted. These publications described experiments in which MPs were added to soil (in laboratory or greenhouse experiments or in the field) after which the soil microbial community was analyzed and compared to a control group. From these publications, we extracted 1315 observations on soil bacterial alpha diversity and richness indices and 845 datasets on gene abundance of bacterial genes related to the soil nitrogen cycle. These data were analyzed using a multiple hierarchical mixed effects meta-analysis. The mean effect of microplastic exposure was a significant decrease of soil bacterial community diversity and richness. We explored these responses for different regulators, namely MPs addition rates, particle size and plastic type, soil texture and land use, and study type. Of the bacterial processes involved in the soil nitrogen cycle, MPs addition significantly promoted assimilation of ammonium, nitrogen fixation and urea decomposition, but significantly inhibited nitrification. These results suggest that MPs contamination may have considerable impacts on soil bacterial community structure and function as well as on the soil nitrogen cycle.

Polyethylene nanoplastics, tebuconazole and cadmium affect soil-wheat system by altering rhizosphere microenvironment under single or combined exposure

Microplastics and nanoplastics (NPs) are pollutants of global concern. However, the understanding of the combined effects of NPs and other pollutants in the soil-plant system remains limited, particularly for polyethylene (PE), the primary component of agricultural films. This study investigated the effects of PE NPs (0.5 %, w/w), fungicide tebuconazole (Te, 10 mg·kg-1), and cadmium (Cd, 4.0 mg·kg-1) on the soil-wheat system under single and combined exposures. The synergistic toxicity observed between NPs and Te impacted the nutritional conditions and antioxidant mechanisms of the soil-wheat system. The NPs increased the concentration of Cd in roots and the proportion of bioavailable Cd, exacerbating oxidative stress in wheat and inhibiting biomass. The soil-wheat system responded to stress by upregulating or downregulating pathways related to carbohydrate, amino acid, and sugar metabolism under various treatments. Sixteen functional genes associated with carbohydrate metabolism, amino acid metabolism, energy utilization, and gene repair at KEGG level 3 were employed to sustain microenvironmental homeostasis. Correlation analysis between microorganisms and environmental factors showed that various PGPG played roles in maintaining the health of the soil-wheat system. These results help to elucidate the comprehensive effects of NPs with other pollutants on the soil-plant system and provide new perspectives for toxic mechanisms.

Revealing the bioavailability and phytotoxicity of different particle size microplastics on diethyl phthalate (DEP) in rye (Secale cereale L.)

Understanding how widely distributed microplastics (MPs) and diethyl phthalate (DEP) interact with crops remains limited, despite their significant implications for human exposure. We used physiology, transcriptomics, adsorption kinetics, and computational chemistry to assess rye's molecular response to two sizes of MPs (200 nm and 5 µm) and DEP, both individually and in combination. Findings systematically highlight potential ecological risks from MPs and DEP, with ecotoxicity ranking as follows: CK (Control Check) < LMPs < SMPs < DEP < LMPs+DEP < SMPs+DEP. Fluorescence and scanning electron microscopy revealed SMP's translocation ability in rye and its potential to disrupt leaf cells. DEP increased the electronegativity on MPs, which enhanced their uptake by rye. DEP adsorption by MPs in hydroponics reduced DEP bioavailability in rye (18.17-46.91 %). Molecular docking studies showed DEP interacted with chlorophyll, superoxide dismutase, and glutathione S-transferases proteins' active sites. Transcriptomic analysis identified significant up-regulation of genes linked to mitogen-activated protein kinase signaling, phytohormones, and antioxidant systems in rye exposed to MPs and DEP, correlating with physiological changes. These findings deepen the understanding of how MPs can accumulate and translocate within rye, and their adsorption to DEP raises crop safety issues of greater environmental risk.

Co-exposure to microplastics and soil pollutants significantly exacerbates toxicity to crops: Insights from a global meta and machine-learning analysis

Environmental contamination of microplastics (MPs) is ubiquitous worldwide, and co-contamination of arable soils with MPs and other pollutants is of increasing concern, and may lead to unexpected consequences on crop production. However, the overall implications of this combined effect, whether beneficial or detrimental, remain a subject of current debate. Here, we conducted a global meta and machine-learning analysis to evaluate the effects of co-exposure to MPs and other pollutants on crops, utilizing 3346 biological endpoints derived from 68 different studies. Overall, compared with control groups that only exposure to conventional soil contaminants, co-exposure significantly exacerbated toxicity to crops, particularly with MPs intensifying adverse effects on crop morphology, oxidative damage, and photosynthetic efficiency. Interestingly, our analysis demonstrated a significant reduction in the accumulation of pollutants in the crop due to the presence of MPs. In addition, the results revealed that potential adverse effects were primarily associated with crop species, MPs mass concentration, and exposure duration. Our study reaffirms the substantial consequences of MPs as emerging pollutants on crops within the context of integrated pollution, providing novel insights into improving sustainability in agro-ecosystems.

Antagonistic Effect of Microplastic Polyvinyl Chloride and Nitrification Inhibitor on Soil Nitrous Oxide Emission: An Overlooked Risk of Microplastic to the Agrochemical Effectiveness

Microplastics are widely persistent in agricultural ecosystems and may affect soil nitrous oxide (N2O) emissions. Nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP) is applied to decelerate nitrification and reduce soil N2O emission. Nevertheless, the interactive effects of nitrification inhibitors and microplastics on soil N2O emissions have not been investigated. Sole DMPP, polyvinyl chloride (PVC), and polystyrene (PS) substantially reduced agricultural soil N2O emission rates by 25.93%, 69.04%, and 73.89%, respectively. Nevertheless, PVC and DMPP had antagonistic effects on the N2O emission rates. The observed reductions in N2O emissions could be attributed to variations in soil oxygen availability, electron transport system activities, and Firmicutes, nap, and GDH genes. Moreover, the DMPP, PVC, and PS alone or copresences significantly enhanced the soil ecosystem multifunctionality (EMF). The findings shed light on the role of microplastics in soil N2O emission, EMF, and the microbial community, expanding the understanding of microplastics' effects on agrochemical effectiveness.

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

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

A critical review of co-pollution of microplastics and heavy metals in agricultural soil environments

The soil environment is a primary destination for contaminants such as microplastics (MPs) and heavy metals (HMs), which are frequently detected simultaneously. The long-term coexistence of MPs and HMs in the soil necessitates unavoidable interactions, affecting their environmental chemical behavior and bioavailability. These co-contaminants pose potential threats to soil organism growth and reproduction, crop productivity, food security, and may jeopardize human health via the food chain. This paper summarizes the sources and trends of MPs in the soil environment, along with the mechanisms and current research status of MP adsorption or desorption of HMs. Additionally, this paper reviews factors affecting HM adsorption on MPs, including MP properties, HM chemical properties, and other environmental factors. Lastly, the effects of MPs and HMs on soil ecology and human health are summarized. The interaction mechanisms and potential biological effects of their co-contamination require further exploration. Future research should delve deeper into the ecotoxic effects of MP-HM co-contamination at cellular and molecular levels, to provide a comprehensive reference for understanding the environmental behavior of their co-contamination in soil.

Micro/nano plastics in the urinary system: Pathways, mechanisms, and health risks

Micro/Nano plastics (MNPs) pollutants are widespread in the environment, raising significant concerns about their biosafety. Emerging studies indicate that the urinary system is a primary accumulation site for MNPs, leading to severe tissue and functional damage. This review aims to summarize recent research on the potential hazards that MNPs may pose to the urinary system, highlighting the mechanisms of toxicity and the current state of knowledge. Studies have shown that MNPs enter the human body through drinking water, the food chain, inhalation, and skin contact. They may penetrate the bloodstream via the digestive, respiratory, and skin systems, subsequently dispersing to various organs, including the urinary system. The potential accumulation of MNPs in the urinary system might induce cellular oxidative stress, inflammation, apoptosis, autophagy, the "intestine-kidney axis", and other possible toxic mechanisms. These processes could disrupt kidney metabolic functions and promote tissue fibrosis, thereby potentially increasing the risk of urinary system diseases. Despite ongoing research, the understanding of MNPs' impact on the urinary system remains limited. Therefore, this review provides a comprehensive overview of MNPs' potential toxicity mechanisms in the urinary system, highlights key challenges, and outlines future research directions. It offers a theoretical basis for the development of effective protective measures and policies.

Microplastic Transport and Accumulation in Rural Waterbodies: Insights from a Small Catchment in East China

Microplastic (MP) pollution in agricultural ecosystems is an emerging environmental concern, with limited knowledge of its transport and accumulation in rural waterbodies. This study investigates the distribution and sources of MP in drainage ditches influenced by pond connectivity, land use, and soil properties within a small catchment in Nanjing, East China. Sediment was collected from ditches in 18 sites across forest, agricultural, horticultural, and urban areas. Using laser-directed infrared spectroscopy (LDIR), 922 MP particles were identified. Six materials were dominant: fluororubber (FR), polyethylene terephthalate (PET), polyurethane (PU), acrylonitrile (ACR), chlorinated polyethylene (CPE), and polyethylene (PE). MP concentrations varied by land use and pond connectivity, with ditches above ponds exhibiting higher counts (1700 particles/kg) than those below (1050 particles/kg), indicating that ponds act as MP sinks. The analysis revealed site-specific MP sources, with FR linked to road runoff and PET associated with agricultural practices. Correlations between MP shape and soil properties showed that more compact and filled shapes were more commonly associated with coarser soils. PE particle size was negatively correlated with organic matter. This study highlights the need for targeted strategies to reduce MP pollution in rural landscapes, such as reducing plastic use, ditch maintenance, and improved road runoff management.

Insights into effects of conventional and biodegradable microplastics on organic carbon decomposition in different soil aggregates

The impacts of microplastics on soil ecological functions such as carbon recycling and soil structure maintenance have been extensively focused. However, the mechanisms underlying the impacts of microplastics on soil carbon transformation and soil microbial community at soil aggregate scale have not been clarified yet. In this work, the effects and action mechanisms of traditional microplastic polypropylene (PP) and degradable microplastic polylactic acid (PLA) on carbon transformation in three sizes of soil aggregates were investigated. The results showed that both PP and PLA promoted CO2 emission, and the effect depended on the type and content of microplastics, and the size of soil aggregates. Changes in soil carbon stocks were mainly driven by changes in organic carbon associated with macroaggregates. For macroaggregates, PP microplastics decreased soil organic carbon (SOC) as well as dissolved organic carbon (DOC). These changes were reversed in microaggregates and silt and clay. Interestingly, PLA increased the SOC, DOC and CO2 emissions in bulk soil and all three aggregates with a dose-effect response. These changes were associated with soil microbes, functional genes and enzymes associated with the degradation of labile and recalcitrant carbon fractions. Furthermore, PP and PLA reduced bacterial community diversities and shifted bacterial community structures in both the three aggregates and in bulk soil. Alterations of functional genes induced by microplastics were the key driving factors of their impacts on carbon transformation in soil aggregates. This research opened up a new insight into the mechanisms underlying the impacts of microplastics on soil carbon transformation, and helped us make rational assessments of the risks and the disturbances of microplastics on soil carbon cycling.

Review of microplastics and chemical risk posed by plastic packaging on the marine environment to inform the Global Plastics Treaty

Plastic overproduction and the resulting increase in consumption has made plastic pollution ubiquitous in all ecosystems. Recognizing this, the United Nations (UN) has started negotiations to establish a global treaty to end plastic pollution, especially in the marine environment. The basis of the treaty has been formulated in terms of turning off the tap, signaling the will to prevent plastic pollution at its source. Based on the distribution of plastic production by sector, the plastic packaging sector consumes the most plastic. The volume and variety of chemicals used in plastic packaging, most of which is single-use, is a major concern. Single-use plastics including packaging is one of the most dominant sources of plastic pollution. Plastic waste causes pollution in water, air and soil by releasing harmful chemicals into the environment and can also lead to exposure through contamination of food with micro- and nano-plastic particles and chemicals through packaging. Marine life and humans alike face risks from plastic uptake through bioaccumulation and biomagnification. While the contribution of plastics ingested to chemical pollution is relatively minor in comparison to other pathways of exposure, the effect of plastic waste on marine life and human consumption of seafood is beyond question. To reduce the long-term impact of plastic, it is crucial to establish a global legally binding instrument to ensure the implementation of upstream rather than downstream solutions. This will help to mitigate the impact of both chemicals and microplastics, including from packaging, on the environment.

Biodegradable microplastics aging processes accelerated by returning straw in paddy soil

Biodegradable microplastics (MPs) have been released into agricultural soils and inevitably undergo various aging processes. Straw return is a popular agricultural management strategy in many countries. However, the effect of straw return on the aging process of biodegradable MPs in flooded paddy soil, which is crucial for studying the characteristics, fate, and environmental implications of biodegradable MPs, remains unclear. Here, we constructed a 180-day microcosm incubation to elucidate the aging mechanism of polylactic acid (PLA)-MPs in straw-enriched paddy soil. This study elucidated that the prominent aging characteristic of PLA-MPs occurred in the straw-enriched paddy soil, accompanied by increased chrominance (76.64-182.3 %), hydrophilicity (2.92-22.07 %), roughness (33.12-58.01 %), and biofilm formation (42.12-100.3 %) for the PLA-MPs, especially with 2 % (w/w) straw return treatment (P < 0.05). A 2 % straw return treatment has significantly impacted ester CO group changes in PLA-MPs, altered the MPs-attached soil bacterial communities composition, strengthened bacterial network structure, and increased soil proteinase K activity. The findings of this work demonstrated that flooded, straw-enriched paddy soil accelerated PLA-MPs aging affected by soil-water chemistry, soil microbe, and soil enzymatic. This study helps to deepen our understanding of the aging process of PLA-MPs in straw return paddy soil. ENVIRONMENTAL IMPLICATION: Microplastics (MPs) are emerging contaminants in the global soil and terrestrial ecosystems. Biodegradable MPs are more likely to be formed and released into agricultural soils during aging. Straw return is a popular agricultural management strategy in many countries. Considering the wide use of plastic film, sewage sludge, plastic-coated fertilizer, and organic fertilizer in agricultural ecosystems, it is crucial to pay attention to the aging process of biodegradable MPs in straw-enriched paddy soil, which has not been adequately emphasized. This aspect has been overlooked in previous studies and threatens ecosystems. This study demonstrated that straw-enriched paddy soil accelerated polylactic acid (PLA)-MPs aging influenced by the dissolved organic matter, microorganisms, and enzyme activity associated with straw decomposition.

Topic modeling discovers trending topics in global research on the ecosystem impacts of microplastics

The ecological threats of microplastics (MPs) have sparked research worldwide. However, changes in the topics of MP research over time and space have not been evaluated quantitatively, making it difficult to identify the next frontiers. Here, we apply topic modeling to assess global spatiotemporal dynamics of MP research. We identified nine leading topics in current MP research. Over time, MP research topics have switched from aquatic to terrestrial ecosystems, from distribution to fate, from ingestion to toxicology, and from physiological toxicity to cytotoxicity and genotoxicity. In most of the nine leading topics, a disproportionate amount of independent and collaborative research activity was conducted in and between a few developed countries which is detrimental to understanding the environmental fates of MPs in a global context. This review recognizes the urgent need for more attention to emerging topics in MP research, particularly in regions that are heavily impacted but currently overlooked.

Significant influence of land use types and anthropogenic activities on the distribution of microplastics in soil: A case from a typical mining-agricultural city

Microplastics pollution in soil has become a prominent issue in the field of ecological environment. However, relevant data on the microplastics pollution characteristics in mining industry-agricultural soil ecosystems is still limited. In this study, an extensive investigation on the characteristics of microplastics pollution in typical mining-agricultural city soil was conducted, revealing abundances, features, and influencing factors of microplastics in five land use types including facility farmland (FF), traditional farmland (TF), residential land (RL), industrial land (IL), and grassland (GL). The results showed that the distribution of microplastics abundances exhibits a nonuniform pattern, and the highest microplastics abundance was found in FF (3738 ± 2097 items·kg-1) compared with the other four land use types of this study area. Moreover, the key polymers identified were polypropylene (PP) and polyethylene (PE) with a smaller size (<0.01 mm) accounting for the majority at ,45 %, primary colors of microplastics were transparent with the dominant shapes being fibers and fragments. Additionally, principal component analysis and cluster analysis characterized microplastics features across various land use patterns, revealing that agricultural plastic waste, irrigation, and fertilization may be the main the primary sources of agricultural microplastics, while domestic sewage, household waste (include construction waste), and mining transportation activities are the potential urban sources. Correlation analysis indicates a positive relationship between TN, TP, SOC, and the abundances of microplastics (P < 0.05), and a negative relationship between pH and microplastic abundances. Furthermore, Cd, Cu, and As exhibit a significant positive correlation with microplastic characteristics (P < 0.05). Notably, the distribution trends of Cd content and microplastic abundance are similar. Overall, comprehensive analysis of environmental dynamics on microplastics in agricultural soil in coal industrial cities is crucial for developing effective measures to prevent and control microplastic pollution.

Traversing the prevalence of microplastics in soil-agro ecosystems: Origin, occurrence, and pollutants synergies

The ubiquity of plastics in modern life has made them a significant environmental concern and a marker of the Anthropocene era. The degradation of plastics results in the formation of microplastics (MPs), which measure 5 mm or less. The coexistence of MPs with other pollutants found in sludge, water treatment plant effluents, surface water, and groundwater, shapes the environmental landscape together. Despite extensive investigation, the long-term implications of MPs in soils remain uncertain, underscoring the importance of delving into their transportation and interactions with soil biota and other contaminants. The present article provides a comprehensive overview of MPs contamination in soil, encompassing its sources, prevalence, features, and interactions with soil flora and fauna, heavy metals, and organic compounds. The sources of MPs in soil agroecosystems are mulching, composting, littering, sewage sludge, irrigation water, and fertilizer application. The concentration of MPs reported in plastic mulch, littering, and sewage sludge is 503 ± 2760 items per kg-1, 4483 ± 2315 MPs/kg, and 11,100 ± 570 per/kg. The transport of MPs in soil agroecosystems is due to their horizontal and vertical migration including biotic and abiotic mobility. The article also highlighted the analytical process, which includes sampling planning, collection, purification, extraction, and identification techniques of MPs in soil agroecosystems. The mechanism in the interaction of MPs and organic pollutants includes surface adsorption or adhesion cation bridging, hydrogen bonding, charge transfer, ligand exchange, van der Waals interactions, and ion exchange.

Plastic takeaway food containers may cause human intestinal damage in routine life usage: Microplastics formation and cytotoxic effect

The microplastics and organic additives formed in routine use of plastic takeaway food containers may pose significant health risks. Thus, we collected plastic containers made of polystyrene, polypropylene, polyethylene terephthalate, polylactic acid and simulated two thermal usages, including hot water (I) and microwave treatments (M). Nile Red fluorescence staining was developed to improve accurate counting of microplastics with the aid of TEM and DLS analysis. The quantity of MPs released from thermal treatments was determined ranging from 285.7 thousand items/cm2 to 681.5 thousand items/cm2 in containers loaded with hot water with the following order: IPS>IPP>IPET>IPLA, while microwave treatment showed lower values ranging from 171.9 thousand items/cm2 to 301.6 thousand items/cm2. In vitro toxicity test using human intestinal epithelial Caco-2 cells indicated decrease of cell viability in raw leachate, resuspended MPs and supernatants, which might further lead to cell membrane rupture, ROS production, and decreased mitochondrial membrane potential. Moreover, the leachate inhibited the expression of key genes in the electron transport chain (ETC) process, disrupted energy metabolism. For the first time, we isolate the actually released microplastics and organic substances for in vitro toxicity testing, and demonstrate their potential impacts to human intestine. SYNOPSIS: Plastic take-out containers may release microplastics and organic substances during daily usage, both of which can cause individual and combined cytotoxic effects on human colon adenocarcinoma cells Caco-2.

Colonization characteristics and surface effects of microplastic biofilms: Implications for environmental behavior of typical pollutants

This paper summarizes the colonization dynamics of biofilms on microplastics (MPs) surfaces in aquatic environments, encompassing bacterial characteristics, environmental factors affecting biofilm formation, and matrix types and characteristics. The interaction between biofilm and MPs was also discussed. Through summarizing recent literatures, it was found that MPs surfaces offer numerous benefits to microorganisms, including nutrient enrichment and enhanced resistance to environmental stress. Biofilm colonization changes the surface physical and chemical properties as well as the transport behavior of MPs. At the same time, biofilms also play an important role in the fragmentation and degradation of MPs. In addition, we also investigated the coexistence level, adsorption mechanism, enrichment, and transformation of MPs by environmental pollutants mediated by biofilms. Moreover, an interesting aspect about the colonization of biofilms was discussed. Biofilm colonization not only had a great effect on the accumulation of heavy metals by MPs, but also affects the interaction between particles and environmental pollutants, thereby changing their toxic effects and increasing the difficulty of MPs treatment. Consequently, further attention and research are warranted to delve into the internal mechanisms, environmental risks, and the control of the coexistence of MPs and biofilms.

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.

Comparing the impact of microplastics derived from a biodegradable and a conventional plastic mulch on plant performance

Agricultural lands have been identified as plastic sinks. One source is plastic mulches, which are a source of micro- and nano-sized plastics in agricultural soils. Because of their persistence, there is now a push towards developing biodegradable plastics, which are designed to undergo (partial) breakdown after entering the environment. Yet, limited research has investigated the impacts of both conventional and biodegradable plastics on distinct plants. Moreover, comparisons among studies are difficult due to differences in experimental design. This study directly compares the effects of artificially weathered conventional polyethylene (PE) and starch-based biodegradable polybutylene adipate terephthalate (PBAT) on four food crops, including two monocots (barley, Hordeum vulgare, and wheat, Triticum aestivum L.) and two dicots (carrot, Daucus carota, and lettuce, Lactuca sativa L.). We investigated the effects of environmentally relevant low, medium, and high (0.01 %, 0.1 %, 1 % w/w) concentrations of PE and starch-PBAT blend on seed germination (acute toxicity), and subsequently on plant growth and chlorophyll through a pot-plant experiment (chronic toxicity). Germination of all species was not affected by both plastics. However, root length was reduced for lettuce and wheat seedlings. No other effects were recorded on monocots. We observed a reduction in shoot length and bud wet weight of carrot seedlings for the highest concentration of PE and starch-PBAT blend. Chronic exposure resulted in a significant decrease in shoot biomass of barley and lettuce. Additionally, a positive increase in the number of leaves of lettuce was observed for both plastics. Chlorophyll content was increased in lettuce when exposed to PE and starch-PBAT blend. Overall, adverse effects in dicots were more abundant than in monocots. Importantly, we found that the biodegradable plastic caused more commonly adverse effects on plants compared to conventional plastic, which was confirmed by a mini-review of studies directly comparing the impact of conventional and biodegradable microplastics.

Transcriptome mechanisms of dandelion under stress of polystyrene and dibutyl phthalate and quantitative tracing of nanoplastics

Polystyrene nanoplastics (PS NPs) and dibutyl phthalate (DBP) pollution pose significant risks to ecosystems and contribute to bioaccumulation in plants, yet uptake mechanisms and combined toxicity are poorly understood. We used fluorescent labeling and europium-doped PS NPs to reveal the absorption and translocation of NPs by dandelions and conducted a transcriptomic analysis under PS NPs and DBP exposure. The results indicated that NPs are transported horizontally through the intercellular gaps at the root tips and primary root-lateral root junctions via the apoplastic pathway, followed by longitudinal transport through the xylem vessels under the transpiration stream. Co-exposure significantly reduced the bioconcentration factors of dandelion seedlings by 113 % but increased the NP transfer factors by 33.8 %. Transcriptomic analysis confirmed that exposure to PS NPs and DBP activated gene expression in dandelion shoots and roots. The differentially expressed genes were primarily involved in the photosynthesis, plant hormone signal transduction, and phenylpropanoid biosynthesis pathways. Weighted gene co-expression network analysis identified key genes and hub transcription factors playing crucial roles in regulating dandelion's response to combined stress. Our study provides new insights into the plant toxicity mechanism underlying the interaction between PS NPs and DBP, highlighting the adverse effects of the combined pollution on plant health.

Earthworms improve the rhizosphere micro-environment to mitigate the toxicity of microplastics to tomato (Solanum lycopersicum)

Microplastics (MPs) are widespread in agricultural soil, potentially threatening soil environmental quality and plant growth. However, toxicological research on MPs has mainly been limited to individual components (such as plants, microbes, and animals), without considering their interactions. Here, we examined earthworm-mediated effects on tomato growth and the rhizosphere micro-environment under MPs contamination. Earthworms (Eisenia fetida) mitigated the growth-inhibiting effect of MPs on tomato plant. Particularly, when exposed to environmentally relevant concentrations (ERC, 0.02% w/w) of MPs, the addition of earthworms significantly (p < 0.05) increased shoot and root dry weight by 12-13% and 13-14%, respectively. MPs significantly reduced (p < 0.05) soil ammonium (NH4+-N) (0.55-0.69 mg/kg), nitrate nitrogen (NO3--N) (7.02-8.65 mg/kg) contents, and N cycle related enzyme activities (33.47-42.39 μg/h/g) by 37.7-50.9%, 22.6-37.2%, and 34.2-48.0%, respectively, while earthworms significantly enhanced (p < 0.05) inorganic N mineralization and bioavailability. Furthermore, earthworms increased bacterial network complexity, thereby enhancing the robustness of the bacterial system to resist soil MPs stress. Meanwhile, partial least squares modelling showed that earthworms significantly influenced (p < 0.01) soil nutrients, which in turn significantly affected (p < 0.01) plant growth. Therefore, the comprehensive consideration of soil ecological composition is important for assessing MPs ecological risk.

Impact of Type and Shape of Microplastics on the Transport in Column Experiments

The pervasive nature of plastic and the longevity of plastics leaves a legacy of microplastics (MPs) that contaminate our environment, including drinking water sources. Although MPs have been documented in every environmental setting, a paucity of research has focused on the transport and fate of MPs in groundwater. Previous field and laboratory studies have shown that MPs can migrate through aquifer material and are influenced by environmental factors. This study used controlled column experiments to investigate the influence of polymer type (polyamide, polyethylene, polypropylene, and polyester) and particle shape (fragment, fiber, and sphere) on MP retardation and retention. The results showed that all individual MP types investigated were retarded compared to the NaCl tracer, with a retardation factor ranging from 1.53 to 1.75. While hypothesized that presence of multiple types and shapes could change mobility, the results indicate that this hypothesis is not correct for the conditions tested. This study provides new insights into MP transport in groundwater systems based on the characteristics of MP particles. In addition, this study demonstrates the need for further research on types of MPs and under more conditions, especially in the presence of a mixture of types and shapes of MPs to gauge what is occurring in natural systems where many MPs are present together.

Beyond surface: Unveiling ecological and economic ramifications of microplastic pollution in the oceans

Every year, the global production of plastic waste reaches a staggering 400 million metric tons (Mt), precipitating adverse consequences for the environment, food safety, and biodiversity as it degrades into microplastics (MPs). The multifaceted nature of MP pollution, coupled with its intricate physiological impacts, underscores the pressing need for comprehensive policies and legislative frameworks. Such measures, alongside advancements in technology, hold promise in averting ecological catastrophe in the oceans. Mandated legislation represents a pivotal step towards restoring oceanic health and securing the well-being of the planet. This work offers an overview of the policy hurdles, legislative initiatives, and prospective strategies for addressing global pollution due to MP. Additionally, this work explores innovative approaches that yield fresh insights into combating plastic pollution across various sectors. Emphasizing the importance of a global plastics treaty, the article underscores its potential to galvanize collaborative efforts in mitigating MP pollution's deleterious effects on marine ecosystems. Successful implementation of such a treaty could revolutionize the plastics economy, steering it towards a circular, less polluting model operating within planetary boundaries. Failure to act decisively risks exacerbating the scourge of MP pollution and its attendant repercussions on both humanity and the environment. Central to this endeavor are the formulation, content, and execution of the treaty itself, which demand careful consideration. While recognizing that a global plastics treaty is not a panacea, it serves as a mechanism for enhancing plastics governance and elevating global ambitions towards achieving zero plastic pollution by 2040. Adopting a life cycle approach to plastic management allows for a nuanced understanding of possible trade-offs between environmental impact and economic growth, guiding the selection of optimal solutions with socio-economic implications in mind. By embracing a comprehensive strategy that integrates legislative measures and technological innovations, we can substantially reduce the influx of marine plastic litter at its sources, safeguarding the oceans for future generations.

Uranium accumulation in environmentally relevant microplastics and agricultural soil at acidic and circumneutral pH

The co-occurrence of microplastics (MPs) with potentially toxic metals in the environment stresses the need to address their physicochemical interactions and the potential ecological and human health implications. Here, we investigated the reaction of aqueous U with agricultural soil and high-density polyethylene (HDPE) through the integration of batch experiments, microscopy, and spectroscopy. The aqueous initial concentration of U (100 μM) decreased between 98.6 and 99.2 % at pH 5 and between 86.2 and 98.9 % at pH 7.5 following the first half hour of reaction with 10 g of soil. In similar experimental conditions but with added HDPE, aqueous U decreased between 98.6 and 99.7 % at pH 5 and between 76.1 and 95.2 % at pH 7.5, suggesting that HDPE modified the accumulation of U in soil as a function of pH. Uranium-bearing precipitates on the cracked surface of HDPE were identified by SEM/EDS after two weeks of agitation in water at both pH 5 and 7.5. Accumulation of U on the near-surface region of reacted HDPE was confirmed by XPS. Our findings suggest that the precipitation of U was facilitated by the weathering of the surface of HDPE. These results provide insights about surface-mediated reactions of aqueous metals with MPs, contributing relevant information about the mobility of metals and MPs at co-contaminated agricultural sites.

A comprehensive evaluation of influencing factors of neonicotinoid insecticides (NEOs) in farmland soils across China: First focus on film mulching

Neonicotinoid insecticide (NEO) residues in agricultural soils have concerning and adverse effects on agroecosystems. Previous studies on the effects of farmland type on NEOs are limited to comparing greenhouses with open fields. On the other hand, both NEOs and microplastics (MPs) are commonly found in agricultural fields, but their co-occurrence characteristics under realistic fields have not been reported. This study grouped farmlands into three types according to the covering degree of the film, collected 391 soil samples in mainland China, and found significant differences in NEO residues in the soils of the three different farmlands, with greenhouse having the highest NEO residue, followed by farmland with film mulching and farmland without film mulching (both open fields). Furthermore, this study found that MPs were significantly and positively correlated with NEOs. As far as we know this is the first report to disclose the association of film mulching and MPs with NEOs under realistic fields. Moreover, multiple linear regression and random forest models were used to comprehensively evaluate the factors influencing NEOs (including climatic, soil, and agricultural indicators). The results indicated that the random forest model was more reliable, with MPs, farmland type, and total nitrogen having higher relative contributions.

Microplastic in an apex predator: evidence from Barn owl (Tyto alba) pellets in two sites with different levels of anthropization

Plastic pollution in terrestrial and freshwater environments and its accumulation along food chains has been poorly studied in birds. The Barn owl (Tyto alba) is an opportunistic and nocturnal apex predator feeding mostly on small mammals. In this note, we reported evidence of microplastics (MPs) contamination in Barn owl pellets collected, for the first time, in two sites with different levels of anthropization (low: natural landscape mosaic vs. high extensive croplands). The following polymers have been recorded: polyvinylchloride (PVC), polyethylene (PE), expanded polyester (EPS), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyester (PL), viscose, and starch-based biopolymer. We found significant higher MPs frequency in the most anthropized site. Our results suggest that pellet' analysis may represent a cost-effective method for monitoring MP contamination along food chains in terrestrial ecosystems.

Aging and mitigation of microplastics during sewage sludge treatments: An overview

Wastewater treatment plants (WWTPs) receive large quantities of microplastics (MPs) from raw wastewater, but many MPs are trapped in the sludge. Land application of sludge is a significant source of MP pollution. Existing reviews have summarized the analysis methods of MPs in sludge and the effect of MPs on sludge treatments. However, MP aging and mitigation during sludge treatment processes are not fully reviewed. Treatment processes used to remove water, pathogenic microorganisms, and other pollutants in sewage sludge also cause surface changes and degradation in the sludge MPs, affecting the potential risk of MPs. This study integrates MP abundance and distribution in sludge and their aging and mitigation characteristics during sludge treatment processes. The abundance, composition, and distribution of sludge MPs vary significantly with WWTPs. Furthermore, MPs exhibit variable degrees of aging, including rough surfaces, enhanced adsorption potentials for pollutants, and increased leaching behavior. Various sludge treatment processes further intensify these aging characteristics. Some sludge treatments, such as hydrothermal treatment, have efficiently removed MPs from sewage sludge. It is crucial to understand the potential risk of MP aging in sludge and the degradation properties of the MP-derived products from MP degradation in-depth and develop novel MP mitigation strategies in sludge, such as combining hydrothermal treatment and biological processes.

Mycorrhizosphere bacteria inhibit greenhouse gas emissions from microplastics contaminated soil by regulating soil enzyme activities and microbial community structure

Microplastics (MPs) accumulation in terrestrial ecosystems can affect greenhouse gases (GHGs) production by altering microbial and soil structure. Presently, research on the MPs effect on plants is not consistent, and underlying molecular mechanisms associated with GHGs are yet unknown. For the first time, we conducted a microcosm study to explore the impact of MPs addition (Raw vs. aged) and Trichoderma longibrachiatum and Bacillus subtilis inoculation (Sole vs. combination) on GHGs emission, soil community structure, physiochemical properties, and enzyme activities. Our results indicated that the addition of aged MPs considerably enhanced the GHGs emissions (N2O (+16%) and CO2 (+21%), respectively), C and N cycling gene expression, microbial biomass carbon, and soil physiochemical properties than raw MPs. However, the soil microbial community structure and enzyme activities were enhanced in raw MPs added treatments, irrespective of the MPs type added to soil. However, microbial inoculation significantly reduced GHGs emission by altering the expression of C and N cycling genes in both types of MPs added treatments. The soil microbial community structure, enzymes activities, physiochemical properties and microbial biomass carbon were enhanced in the presence of microbial inoculation in both type of MPs. Among sole and combined inoculation of Trichoderma and Bacillus subtilis, the co-applied Trichoderma and Bacillus subtilis considerably reduced the GHGs emission (N2O (-64%) and CO2 (-61%), respectively) by altering the expression of C and N cycling genes regardless of MPs type used. The combined inoculation also enhanced soil enzyme activities, microbial community structure, physiochemical properties and microbial biomass carbon in both types of MPs treatment. Our findings provide evidence that polyethylene MPs likely pose a high risk of GHGs emission while combined application of Trichoderma and Bacillus subtilis significantly reduced GHGs emission by altering C and N cycling gene expression, soil microbial community structure, and enzyme activities under MPs pollution in a terrestrial ecosystem.

Polyethylene microplastic modulates lettuce root exudates and induces oxidative damage under prolonged hydroponic exposure

Root exudates are pivotal in plant stress responses, however, the impact of microplastics (MPs) on their release and characteristics remains poorly understood. This study delves into the effects of 0.05 % and 0.1 % (w/w) additions of polyethylene (PE) MPs on the growth and physiological properties of lettuce (Lactuca sativa L.) following 28 days of exposure. The release characteristics of root exudates were assessed using UV-vis and 3D-EEM. The results indicated that PE increased leaf number but did not significantly affect other agronomic traits or pigment contents. Notably, 0.05 % PE increased the total root length and surface area compared to the 0.1 % addition, while a non-significant trend towards decreased root activity was observed with PE MPs. PE MPs with 0.1 % addition notably reduced the DOC concentration in root exudates by 37.5 %, while 0.05 % PE had no impact on DOC and DON concentrations. PE addition increased the SUVA254, SUVA260, and SUVA280 values of root exudates, with the most pronounced effect seen in the 0.05 % PE treatment. This suggests an increase of aromaticity and hydrophobic components induced by PE addition. Fluorescence Regional Integration (FRI) analysis of 3D-EEM revealed that aromatic proteins (region I and II) were dominant in root exudates, with a slight increase in fulvic acid-like substances (region III) under 0.1 % PE addition. Moreover, prolonged PE exposure induced ROS damage in lettuce leaves, evidenced by a significant increase in content and production rate of O2·-. The decrease in CAT and POD activities may account for the lettuce's response to environmental stress, potentially surpassing its tolerance threshold or undergoing adaptive regulation. These findings underscore the potential risk of prolonged exposure to PE MPs on lettuce growth.

Microplastics induced the differential responses of microbial-driven soil carbon and nitrogen cycles under warming

The input of microplastics (MPs) and warming interfere with soil carbon (C) or nitrogen (N) cycles. Although the effects of warming and/or MPs on the cycles have been well studied, the biological coupling of microbial-driven cycles was neglected. Here, the synergistic changes of the cycles were investigated using batch incubation experiments. As results, the influences of MPs were not significant at 15, 20, and 25 °C, and yet, high temperature (i.e., 30 °C) reduced the respiration of high-concentration MPs-amended soil by 9.80%, and increased dissolved organic carbon (DOC) by 14.74%. In contrast, high temperature did not change the effect of MPs on N. The decrease of microbial biomass carbon (MBC) and the constant of microbial biomass nitrogen (MBN) indicated that microbial N utilization was enhanced, which might be attributed to the enrichments of adapted populations, such as Conexibacter, Acidothermus, and Acidibacter. These observations revealed that high temperature and MPs drove the differential response of soil C and N cycles. Additionally, the transcriptomic provided genomic evidence of the response. In summary, the high temperature was a prerequisite for the MPs-driven response, which underscored new ecological risks of MPs under global warming and emphasized the need for carbon emission reduction and better plastic product regulation.

Adsorption of Pb(II) by UV-aged microplastics and cotransport in homogeneous and heterogeneous porous media

To investigate the adsorption effects of aged microplastics (MPs) on Pb(II) and their co-transport properties in homogeneous (quartz sand) and heterogeneous (quartz sand with apple branches biochar) porous media, we explored the co-transport of UV-irradiated aged MPs and coexisting Pb(II) along with their interaction mechanisms. The UV aging process increased the binding sites and electronegativity of the aged MPs' surface, enhancing its adsorption capacity for Pb(II). Aged MPs significantly improved Pb(II) transport through homogeneous media, while Pb(II) hindered the transport of aged MPs by reducing electrostatic repulsion between these particles and the quartz sand. When biochar, with its loose and porous structure, was used as a porous medium, it effectively inhibited the transport capacity of both contaminants. In addition, since the aged MPs cannot penetrate the column, a portion of Pb(II) adsorbed by the aged MPs will be co-deposited with the aged MPs, hindering Pb(II) transport to a greater extent. The transport experiments were simulated and interpreted using two-point kinetic modeling and the DLVO theory. The study results elucidate disparities in the capacity of MPs and aged MPs to transport Pb(II), underscoring the potential of biochar application as an effective strategy to impede the dispersion of composite environmental pollutants.

Evaluation of niche, diversity, and risks of microplastics in farmland soils of different rocky desertification areas

The occurrence, sources, effects, and risks of microplastics (MPs) in farmland soils have attracted considerable attention. However, the pollution and ecological characteristics of MPs in farmland soils at different levels of rocky desertification remain unclear. We collected and analyzed farmland soil samples from rocky desertification areas in Guizhou, China, ranging from no to heavy risks. We explored differences and migration of MPs across these areas, unveiled the relationship between diversity, niche, and risks of MPs, and determined influencing factors. The average abundance of soil MPs was 8721 ± 3938 item/kg, and the abundance and contamination factor (CF) of MPs escalated with the increase in rocky desertification level. Diversity, niche, and risk of soil MPs in different rocky desertification areas were significantly different. Rocky desertification caused both MP community differences and linked MP communities at different sites. Diversity and niche significantly affected MP risk (p < 0.05). Environmental factors with significant correlations (p < 0.05) with the abundance and ecological characteristics of MPs varied significantly in soils of different rocky desertification areas. This study advances our comprehension of MP pollution in farmland soils within rocky desertification areas, offering essential data and theoretical insights for the development of control strategies.

Impact of microplastic particle size on physiological and biochemical properties and rhizosphere metabolism of Zea mays L.: Comparison in different soil types

The effect of microplastics (MPs) on plant growth has received increasing attention. However, whether soil texture and MPs size influence the toxicological effects of MPs on plants is unknown. To address this knowledge gap, two soils with different physical structures (lime concretion black and silty loam soils) were selected to explore the potential toxicity of MPs of different particle sizes to maize growth. The results showed that, in both soils, the harm caused by small MPs on maize growth was greater than that caused by large MPs. Low MPs concentrations had no significant effect on maize growth between two soil types; however, when exposed to a concentration of 1 % large MPs, the dry biomass of maize was promoted in lime concretion black soil but inhibited in silty loam soil. All MPs-exposed treatments resulted in a high level of superoxide anions in maize roots, resulting in an increase in the root aerenchyma area and reducing the metabolic activity of maize roots. Metabolomics showed that MPs exposure affected multiple amino acid metabolic pathways, including phenylalanine and tyrosine metabolism, and inhibited lignin biosynthesis in roots. This study provides a theoretical basis for a more comprehensive assessment of the effect of MPs pollution on agricultural production.

Uncovering the intricate relationship between plant nutrients and microplastics in agroecosystems

Recent scientific and media focus has increased on the impact of microplastics (MPs) on terrestrial and soil ecosystems. However, the interactions between MPs with macronutrients and micronutrients and their potential consequences for the agroecosystem are not well understood. Wheat (Triticum aestivum) is a staple food grown globally and has special importance for nations economies. Different elements can cause dangerous outcomes for wheat quality and production yield. In this study, batch adsorption experiments were done using 1 g of polyethylene tetra phthalate MP particles (PET-MPs) in varying concentrations of thirteen elements. The adsorption data were fitted by two common adsorption models (Langmuir and Freundlich). The effect of pH on the speciation of elements in aqueous solutions was investigated. The non-invasive characterization methods indicate the importance of O- and H-containing groups as the main component of selected MPs in controlling the adsorption of the elements ions. In the current study, adsorption and potential transport of the adsorbed macronutrients (K and Na) and micronutrients (Ni, Co, Cu, Al, Ba, Se, Fe, As, B, V and Ag) which include some beneficial (Na, Se, V), and non-essential or toxic elements (Al, As, Ag, Ba) onto MPs to the simulated roots of wheat were evaluated. The maximum sorption capacities of K+> Ni+2> Na+ > Co2+> Cu2+>Al+3 >Ba+2 >Se4+>Fe2+ >As5+ >B3+ >V5+> Ag + on PET-MPs at pH 5.8 and 25 ± 1 °C were 290.6 > 0.52> 0.51 > 0.20> 0.10 > 0.051> 0.024 > 0.003> 0.003 > 0.0015> 5.05 × 10-4> 1.7 × 10-4>3.7 × 10-6 mg g-1, respectively. The results highlight the importance of PET-MPs in controlling element adsorption in the rhizosphere. Our observations provide a good start for understanding the adsorption of multiple elements from the soil rhizosphere zone by PET-MPs.

Earthworms mediate the influence of polyethylene (PE) and polylactic acid (PLA) microplastics on soil bacterial communities

There is a growing body of evidence that suggests that both biodegradable and conventional (non-degradable) microplastics (MP) are hazardous to soil health by affecting the delivery of key ecological functions such as litter decomposition, nutrient cycling and water retention. Specifically, soil fauna may be harmed by the presence of MPs while also being involved in their disintegration, degradation, migration and transfer in soil. Therefore, a comprehensive understanding of the interactions between MPs and soil fauna is essential. Here, we conducted a 120-day soil microcosm experiment applying polyethylene (PE) and polylactic acid (PLA), in the absence/presence of the earthworm Eisenia nordenskioldi to estimate the relative singular and combined impact of MPs and earthworms on the soil bacterial community. Our findings revealed contrasting effects of PE and PLA on the composition and diversity of soil bacteria. All treatments affected the community and network structure of the soil bacterial community. Compared to the control (no MPs or earthworms), PE decreased bacterial alpha diversity, while PLA increased it. Patescibacteria were found to be significantly abundant in the PE group whereas Actinobacteria and Gemmatimonadetes were more abundant in PE, and PLA and earthworms groups. The presence of earthworms appeared to mediate the impact of PE/PLA on soil bacteria, potentially through bacterial consumption or by altering soil properties (e.g., pH, aeration, C availability). Earthworm presence also appeared to promote the chemical aging of PLA. Collectively, our results provide novel insights into the soil-fauna-driven impact of degradable/nondegradable MPs exposure on the long-term environmental risks associated with soil microorganisms.