Microplastic and mesoplastic pollution in farmland soils in suburbs of Shanghai, China

Towards sustainable agroecosystems: A life cycle assessment review of soil-biodegradable and traditional plastic mulch films

The increasing use of traditional agricultural plastic mulch films (PMs) has raised significant environmental concerns, prompting the search for sustainable alternatives. Soil-biodegradable mulch films (BDMs) are often proposed as eco-friendly replacements; however, their widespread adoption remains contentious. This review employs a comparative life cycle assessment perspective to evaluate the environmental impact of PMs and BDMs across their production, use, and end-of-life stages, providing strategies to mitigate their impact on agroecosystems. BDMs generally exhibit lower energy use and greenhouse gas emissions than PMs but contribute to greater land-use demands. Reported eutrophication and acidification potentials are less consistent, varying based on feedstock types and the scope of assessment of BDM, as well as the end-of-life management of PM. The environmental burden of both mulch types is influenced by the life cycle stage, polymer composition, farming practices, additives, film thickness, and local climatic conditions. The manufacturing stage is a major contributor to energy use and greenhouse gas emissions for both PMs and BDMs, despite their shared benefits of increasing crop yields. However, post-use impacts are more pronounced for PMs, driven by end-of-life strategy and adsorbed waste content. While starch-based BDMs offer a more sustainable alternative to PMs, uncertainties regarding the residence time of BDM residues in soil (albeit shorter than PM residues) and their effects on soil health, coupled with higher production costs, impede widespread adoption. For BDM end-of-life, soil biodegradation is recommended. Energy and material recovery options are crucial for PM end-of-life, with mechanical recycling preferred, although it requires addressing eutrophication and human toxicity. This review discusses these complexities within specific contexts and provides actionable insights to guide the sustainable integration of mulch films into agricultural practices.

Establishment and application of standard analysis methods for microplastic samples: Urban sewage and sewage sludge as a source of microplastics in the environment

The widespread use of plastics has led to the ubiquitous presence of microplastics (MPs) in the environment, posing risks to ecosystems and human health. Wastewater treatment plants (WWTPs), which often fail to completely remove MPs during treatment, have become a significant source of pollution. However, inconsistencies in sampling, pretreatment, and identification methods hinder comparative studies. This study developed a standardized method for MP analysis in WWTP water and sludge samples. Metal filters and ultrasound-assisted transfer improved desorption efficiency, while NaI flotation achieved nearly complete MP recovery. A two-step digestion method combining Fenton reagent and cellulase effectively removed organic matter (weight loss of 54.21 ± 2.00%) while maintaining 100% MP recovery. By tailoring the method to variables such as treatment processes, water volume, and pollution sources, a "gold standard" approach was designed to evaluate the environmental abundance of MPs in various WWTPs. Application of this method revealed MP concentrations of 2530-18,240 MP/L in influent and 650-1700 MP/L in effluent, with an estimated daily discharge of 1.42 × 108 MP/d into the environment. Primary sedimentation and skimming removed 57.07% of MPs, with secondary and advanced treatments enhancing removal. MPs primarily transferred to sludge, averaging 38.6-104.5 MP/g (dry weight). The most abundant MPs in influent were PU, PET, and PTFE, while PA, PU, and PET dominated in effluent. MPs smaller than 0.5 mm accounted for 98%, with regular particles increasing in effluent. This efficient method establishes a "gold standard" for MP analysis in WWTPs.

Seasonal variations and risk assessment of microplastic contamination in agricultural soil and associated macroinvertebrates in Egypt

Contamination by microplastics (MPs) has the potential to rank among the world's most significant environmental issues. Despite the fact that MP contamination is a global problem, little is known about the time variation of MPs in agricultural soil and its faunal communities which represent a key role to risk assessment. This study represents a first field investigation regarding the MP concentrations in agricultural ecosystem in Egypt. Our study investigates the seasonal fluctuations of MPs in soil and its common fauna in a citrus orchard (Citrus sinensis) in Egypt's Sohag Governorate. Moreover, this work aimed to identify how feeding strategies and body size of the selected fauna affect the no. of MPs ingested. The greatest mean concentration of MPs in soil was observed in summer (664 ± 90.20 items/kg) dry weight. However the lowest was recorded in autumn (354 ± 70.92 items/kg). Aporrectodea caliginosa (earthworms) was more contaminated with MPs (6.84 ± 2.5 item/individual annually) than Anisolabis maritima (earwigs) (2.06 ± 0.86 item/individual annually). When comparing between taxa without considering the size of the organisms, earwigs showed higher MPs concentrations (ranged from 117.93 ± 5.23 to 244.38 ± 4.57 items/gm wet weight) than the earthworms (ranged from 25.62 ± 2.43 to 51.66 ± 4.05 items/gm wet weight). Our results found that blue and red colors were the predominant colors in the soil and the selected fauna. Also, polyester fibers (PES) were the most popular type of microplastics, followed by fractions of polyethylene (PE) and polypropylene (PP). Interestingly, the reduction in the MP particles in the present taxa was observed compared to those in the soil. Pollution load index (PLI) value varied across seasons, with the lowest recorded in autumn due to reduced MPs abundance. The Hazard (H) index indicates a moderate risk (level III) due to high polyester abundance and a low hazard score (4) across all seasons. Our results represent a starting point for further studies on the impact of MPs on soil organisms in various agricultural soils.

Occurrence, ecological risk of microplastics in campus athletic fields runoff and their adsorption behavior towards heavy metals

The occurrence of microplastics in athletic fields and their risk of ecological pollution have attracted widespread attention. The abundance, particle size, morphology, color and type of microplastics as well as their ecological risk are conducted in five types of athletic fields runoff on a campus in Beijing. The concentration of microplastics in the stormwater runoff of the five athletic fields ranges 2433 ± 493 to 5067 ± 839 particles/L, composed of fibers, granules and fragments. Fibers microplastics (41-64%) are the most abundant in stormwater runoff samples from most athletic fields, followed by granules (26-45%), and fragments (8-18%). ATR-FTIR and micro-FTIR identify the types of microplastics in runoff from athletic fields as EPDM, SBR, PE, PP, PO, rayon, and nylon. The degree of microplastic pollution is ranked level II-III pollution, which posing potential health and ecological risks. The adsorption behavior is tested for three types of microplastic particles including ethylene propylene diene monomer (EPDM), styrene-butadiene rubber (SBR) and aged-SBR particles derives from athletic fields surface materials towards runoff typical heavy metals Pb and Zn. The adsorption isotherms are more in line with the Langmuir model, indicating a chemical monolayer adsorption. The maximum adsorption capacity towards Pb and Zn follow the order of EPDM (2.67 mg/g) > aged-SBR (1.50 mg/g) > SBR (0.13 mg/g), and EPDM (2.61 mg/g) > aged-SBR (1.50 mg/g) > SBR (0.56 mg/g), respectively. Aged microplastics are subjected to processes such as UV aging and weathering, the surface layer is more likely to acquire charges and adsorb metals to maintain charge balance. EPDM, SBR and aged-SBR particles all contain Ca, Zn, and Mg, which can undergo displacement reactions with Pb and Zn. FTIR results indicate that the adsorption of heavy metals may alter the surface chemical properties of microplastics, rendering them more polar. XPS results reveal that the changes in surface functional groups of EPDM are more pronounced before and after adsorption compared to SBR and aged-SBR, indicating that chemical adsorption plays a dominant role in this process. Microplastics in runoff from athletic fields is an important source of microplastic release, and the occurrence of microplastics needs to attract further attention. The adsorption of microplastics and pollutants in athletic field runoff could exacerbate their combined pollution, thus their ecological risks cannot be ignored.

Biofilm colonization on non-degradable and degradable microplastics change the adsorption of Cu(II) and facilitate the dominance of pathogenic microbes

Microplastics (MPs) have become a global concern as they can accumulate pollutants in aquatic environments. In this research, Cu(II) and non-degradable (polyamide, PA), degradable (polylactic acid, PLA) MPs were employed to reveal the potential connection among different aged MPs and heavy metal pollutants. The aging processes of MPs induced alterations in the surface morphologies, led to an augmentation of the specific surface area, and formed more biofilm and oxygen-containing groups on the MPs surface. The Qe of PA and PLA MPs increased from 0.102 to 0.989 to 1.192 and 2.457 mg/g after aging, respectively. The analysis of site energy distribution further verified that the enhanced adsorption capacity resulted from more high-energy adsorption sites obtained during the aging processes of MPs. Moreover, pathogenic bacteria and resistant bacteria were accumulated on the surface of MPs regardless of the aging environment, and the abundance and diversity of pathogenic bacteria on the biofilm of the PA surface were greater than those on the PLA MPs. This research offers an insight into the mechanism underlying microbial colonization and adsorption in the relationship between MPs and Cu(II), which is beneficial for judging the enrichment of heavy metals on MPs within the aquatic environment.

Using feral pigeon (Columba livia) to monitor anthropogenic debris in urban areas: a case study in Taiwan's capital city

The terrestrial environment is a significant source of anthropogenic debris emissions. While most studies on anthropogenic debris focus on the marine environment, our research delves into the effects of human activity on anthropogenic debris ingestion by studying the carcasses of feral pigeons. From January to June 2022, we collected the gastrointestinal tracts (GI tracts) of 46 pigeon carcasses in Taipei, Taiwan's capital city. The results revealed that 224 anthropogenic debris samples were found, with the dominant form being fibers (71.9%), which are primarily black (29.9%). Fourier transform infrared spectroscopy (FTIR) revealed that the main component of anthropogenic debris is polyethylene (PE) (20.5%), followed by anthropogenic cellulose (19.2%) and various other plastics. This study revealed that the amount of anthropogenic debris and chemical composition in the GI tract significantly increase with increasing human activity. These results prove that feral pigeons are valuable indicators for monitoring anthropogenic debris pollution in urban ecosystems. On the other hand, past research focused on analyzing microplastics, but we confirmed that the GI tract of pigeons has a high proportion of anthropogenic cellulose. Importantly, future studies should consider the potential impacts of anthropogenic cellulose in terrestrial ecosystems, as this could have significant implications for ecosystem health.

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.

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.

Evaluating the impacts of microplastics on agricultural soil physical, chemical properties, and toxic metal availability: An emerging concern for sustainable agriculture

Microplastics (MPs) are an emerging environmental issue that might endanger the health of agricultural soil. Even though several research on the particular toxicity of MPs to species have been carried out, there is little information on MPs' impacts on soil physicochemical properties and heavy metals (HMs) availability of HMs contaminated and without contaminated soils. This study examined the changes in soil characteristics for both HMs contaminated and without contaminated soils by five distinct MPs, including Polyethylene (PE), Polyethylene terephthalate (PET), Polystyrene Foam (PS), Polyamide (PA), and a combination of these four types of MPs (Mixed MPs), at two different concentrations (0.2% and 1%; w/w), where soil incubation experiments were setup for this studies and the standard analytical techniques employed to measure soil characteristics and toxic metal availability. After the ending of soil incubation studies (90 days), significant changes have been observed for physicochemical properties [bulk density, porosity, water holding capacity, pH, electrical conductivity (EC), organic carbon (OC), and organic matter (OM)]. The soil nutrients change in descending order was found as NH4+ -N> PO43+ > Na > Ca > NO3- > Mg for lower concentrations of MPs compared to higher concentrations. The HMs availability is reducing with increasing MPs concentration and the descending order for metal availability was as follows Pb > Zn > Cd > Cr > Cu > Ni. Based on MP type, the following descending order of MPs PS > Mix (MPs) > PA > PET > PE, respectively act as a soil properties influencer. Usually, effects were reliant on MPs' category and concentrations. Finally, this study concludes that MPs may modify metal movements, and soil quality; consequently, a possible threat will be created for soil health.

Environmental impact of microplastics and potential health hazards

Microscopic plastic (microplastic) pollutants threaten the earth's biodiversity and ecosystems. As a result of the progressive fragmentation of oversized plastic containers and products or manufacturing in small sizes, microplastics (particles of a diameter of 5 mm with no lower limit) are used in medicines, personal care products, and industry. The incidence of microplastics is found everywhere in the air, marine waters, land, and even food that humans and animals consume. One of the greatest concerns is the permanent damage that is created by plastic waste to our fragile ecosystem. The impossibility of the complete removal of all microplastic contamination from the oceans is one of the principal tasks of our governing body, research scientists, and individuals. Implementing the necessary measures to reduce the levels of plastic consumption is the only way to protect our environment. Cutting off the plastic flow is the key remedy to reducing waste and pollution, and such an approach could show immense significance. This review offers a comprehensive exploration of the various aspects of microplastics, encompassing their composition, types, properties, origins, health risks, and environmental impacts. Furthermore, it delves into strategies for comprehending the dynamics of microplastics within oceanic ecosystems, with a focus on averting their integration into every tier of the food chain.

Interfacial sorption of 17β-E2 on nano-microplastics: Effects of particle size, functional groups and hydrochemical conditions

Nano-microplastics and 17β-E2 have been frequently detected as emerging high-concern pollutants in aquatic systems, and their interaction at the solid/liquid interface has become a research focus in environmental studies. The interfacial sorption kinetics and equilibrium characteristics of 17β-estradiol (17β-E2) on nano-polystyrene (Nano-PS) with different particle sizes and organic functional group modifications were systematically investigated in aqueous environments in this study. The interfacial interaction mechanism between Nano-PS particles and 17β-E2 was elucidated by utilizing SEM, FTIR, XPS and BET techniques. The experimental results demonstrated that the interfacial sorption kinetics of 17β-E2 on different Nano-PS were rapid, in accordance with the pseudo-first-order models. Both Langmuir and Freundlich models provided a nice description of 17β-E2 sorption equilibrium on Nano-PS, indicating that physical effects predominantly governed the interfacial interactions. Modification of Nano-PS by -OH and -NH2 resulted in increase in polarity, decrease in hydrophobicity and reduction in the sorption capacity for 17β-E2, suggesting that hydrophobic partitioning primarily controlled the interfacial interaction between Nano-PS and 17β-E2. Furthermore, the superior sorption capacity of PS100-OH relative to PS100-NH2 can primarily be attributed to the enhanced hydrogen bonding capability provided by the -OH group. The sorption capacity of 17β-E2 by the same Nano-PS was inversely proportional to the particle size, indicating that a smaller particle size possessed larger specific surface area, thereby providing more active sites and facilitating more pore filling. Low temperature promoted the sorption process and increased the sorption capacity. This study established a scientific foundation for better assessment of the environmental behavior arising from co-pollution of nano-microplastics and endocrine disruptors (EDCs).

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

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

An introduction to machine learning tools for the analysis of microplastics in complex matrices

As microplastic (MP) particles continue to spread globally, their pervasive presence is increasingly problematic. Analyzing MPs in matrices as varied as soil, river water, and biosolid fertilizers is critical, as these matrices directly impact the food sources of plants, animals, and humans. Current analytical methods for quantifying and identifying MPs are limited due to labor-intensive extraction processes and the time and effort required for counting and analysis. Recently, Machine Learning (ML) has been introduced to the analysis of MPs in complex matrices, significantly reducing the need for extensive extraction and increasing analysis speeds. This work aims to illuminate various ML techniques for new researchers entering this field. It highlights numerous examples in the application of these models, with a particular focus on spectroscopic techniques such as infrared and Raman spectroscopy; tools which are used to quantify and identify MPs in complex matrices. By demonstrating the effectiveness of these computer-based tools alongside the hands-on techniques currently used in the field, we are confident that these ML methodologies will soon become integral to all aspects of microplastic analysis in the environmental sciences.

Assessment of Four Artificial Methods for Aging Plastic Mulch Films According to Efficiency, Rate, and Similarity to Natural Field-Aged Plastics

Artificial degradation is often used to recreate and accelerate the natural aging of plastic for small-scaled simulation experiments assessing their environmental impact. However, current artificial aging methods are rarely compared against reference materials or validated using field-aged samples, creating uncertainties when extrapolating results to naturally aged plastics, making it difficult to place findings in an environmentally applicable context. Therefore, here we compared four accessible, cost-effective, and easily replicable methods (heat, UVA, and UVC irradiance at two intensities) to produce artificially degraded materials. The artificial aging methods were assessed over a duration of 5 months against degradation rate, efficiency, and similarity to field-aged samples of conventional and biodegradable plastic mulch film over a 6-month field exposure period. We utilised attenuated total reflectance-Fourier transform infrared spectroscopy to calculate the carbonyl index and measure chemical changes of the mulch film surface, as well as differential scanning calorimetry and thermogravimetric analysis. Physical changes were assessed by thickness and surface roughness measurements. We found that UVA was the most suitable and realistic artificial degradation method at a medium rate, whilst UVC is recommended for rapid degradation without the need to simulate realistic changes, and heat for processing large volumes of samples without a requirement for realistic degradation over a prolonged time period. However, the methods compared in this study yielded differential results depending on polymer type and parameter of interest. We therefore recommend establishing the degradation aim, identifying the spectral region of interest, and accounting for different polymer types to select the most appropriate method.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10924-024-03481-5.

Microplastic contamination and environmental risks in the Beas River, western Himalayas

The Western Himalayan mountains, with several riverine systems, are considered one of the most fragile environments in the world. Among them is Beas, a primary river that provides essential ecosystem benefits to thousands of indigenous people in North India. One of the major pollutants, microplastics (MPs), are ubiquitous contaminants, yet their occurrence in the Beas and ecological risk factors remain largely unexplored. Due to extensive tourism and urban-related burdens, the usage and release of enormous amounts of plastics and MPs into the Beas are apparent. Here, we investigated the extent of MPs pollution and subsequent environmental risks in water and sediments from Beas along a stretch of 300 km. Our results showed that MPs were abundant and widely distributed, with the abundance range (mean ± SE) being 46-222 (112.27 ± 12.43) items/L in water and 36-896 (319.47 ± 49.25) items/kg in sediment samples. We found significant differences in MPs' abundance in water but not sediments among the five sampling sites. There was a significant positive correlation between population size and the abundance of MPs, with the highest abundance in populated Kullu and the lowest loads at the remote Dhundi Glacier. Fibers and film were common morphotypes; most items measured <1 mm. Of the eleven polymers identified, the majority were polyethylene. The pollution load index ranged up to 4.99 (low-risk category); however, the polymer hazard index exceeded 1000 (highest-risk category), and the potential ecological risk index was 13,761 (extreme-risk category) at selected sites. This study fills a crucial knowledge gap and raises concerns about the possible impact on human health, as many riparian residents depend on Beas as their primary source of potable water. Our findings may assist governmental agencies in formulating comprehensive eco-friendly policies and advancing environmentally sustainable strategies in vulnerable locales adjoining the Beas waterway.

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.

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

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

Forensic determination of adhesive vinyl microplastics in urban soils

Plastic production and consumption hubs are mainly concentrated in urban centers, causing the soil in these places to become sinks of plastic fragments. Adhesive vinyl polymers are widely used in various commercial sectors and, to the best of our knowledge, this is the first study to investigate the potential for this type of material to form microplastics in urban soils. This proof-of-concept work started by studying the soil around a sign made of adhesive vinyl that had been exposed to the weather for eight years and showed evident signs of degradation, like cracking and color fading. We separated the microplastics with a two-step density separation protocol and selected only the microplastics targeted by this research, finding up to 5,570 fragments produced from 1 cm2 of adhesive vinyl film. In the soil below the sign, we registered 5.6 × 104 fragments kg-1 of dry soil on its topsoil layer (0-10 cm), 1.2 × 104 fragments kg-1 in the 10-20 cm layer, and 1 × 104 fragments kg-1 in the 20-30 layer. At a distance of 1 and 2 m from the sign, the highest concentration of fragments was also in the topsoil, respectively 9.3 × 103 and 5.3 × 102 fragments kg-1. We also observed that vertical and horizontal transport was not favored, causing the formation of hotspots near the source and that the area of the fragments did not influence vertical transport. Another important finding regarding the characterization technique is that degraded polyvinyl chloride is unlikely to be identified through FTIR without comparison to the source. Here, we presented a low-cost forensic assessment of the association between the presence of MPs and its source that can be used both for the development of public policies and for setting up quality controls for polluting companies.The results here presented reveal the need to rethink the use and types of materials used for visual identities and signage in urban environments.

Macro- and micro-plastic accumulation in soils under different intensive farming systems: A case study in Quzhou county, the North China Plain

The macroplastics (MaPs) and microplastics (MiPs) polluting agricultural soils raise great concerns. Unfortunately, scientists know little about the occurrence of MaPs/MiPs in soil among different farming systems. In this study, we analyzed MaPs/MiPs in soils (0-30 cm) collected from six different farming systems (wheat-maize rotations, cotton, vegetables, permanent orchards, greenhouses with and without mulching) in Quzhou county, the North China Plain, by using fluorescence microscope and micro-Fourier transform infrared spectroscopy. The results showed that the abundance of MaPs and MiPs ranged from 0.2 to 46.8 kg ha-1, and 4.1 × 103-3.7 × 104 items kg-1, respectively. The prominent colors of the MaPs were white and black. The predominant shape, size and chemical composition of soil MiPs were fragments (45-62%), <1 mm (98-99%), and polyethylene (38-43%), respectively. MaPs were mainly detected in the 0-10 cm soil layer. MiP abundance in the 0-10 cm soil layer was significantly higher than that in the 20-30 cm soil layers among different farming systems, except for the fields with wheat-maize rotations and permanent orchards (p < 0.05). Overall, cotton fields showed the highest MaP and MiP abundance, followed by vegetable fields and orchards. Redundancy analysis revealed that tillage practices and plastic film management greatly influence the size distribution of MiPs. A strong negative correlation between large-sized plastic fractions (0.2-1 mm) and tillage frequency was tested while the years of application of plastic films and the abundance of plastic residues showed a strong positive correlation with small-sized plastic fractions (<0.2 mm). Our findings conclude that agricultural mulch films are an important source of MaPs and MiPs in agricultural soil and distributions are strongly influenced by agricultural management practices and farming systems. Further studies should take farming systems and farming practices into account, thereby exploring the potential mechanisms of plastic fragmentation and granularization in agricultural soil.

Waterborne contaminants in high intensity agriculture and plant production: A review of on-site and downstream impacts

Waterborne contaminants pose a significant risk to water quality and plant health in agricultural systems. This is particularly the case for relatively small-scale but intensive agricultural operations such as plant production nurseries that often rely on recycled irrigation water. The increasing global demand for plants requires improved water quality and more certainty around water availability, which may be difficult to predict and deliver due to variable and changing climate regimes. Production nurseries are moving to adopt best management practices that recycle water; however, the risks associated with waterborne contaminants of various types, including nutrients, pesticides, plant pathogens, micro-plastics, and toxic metals, are not well understood. We review and synthesise the physical and biogeochemical factors that contribute to waterborne contaminant risk, and the main types of contaminants that are likely to require management, at plant production nurseries. Catchment characteristics (i.e., topography, land use), hydroclimatic factors (i.e., storms, floods, droughts), and landscape hydrological and sediment connectivity influence surface runoff, sediment transport, and associated contaminant transfer and storage. High hydrological connectivity can increase the risk of contaminant transport from the surrounding landscape to nurseries, with potential negative impacts to water quality in reservoirs and in turn plant health. High connectivity may also increase the risk of contaminants (e.g., sediment, pesticides, and phytopathogens) being transferred from nursery farms into downstream waterways, with consequences for aquatic ecosystems. Like all intensive agricultural operations, nurseries need to consider sources of irrigation water, water treatment and management strategies, and catchment and hydroclimatic factors, to mitigate the spread of contaminants and reduce their impacts on both plant production and the surrounding environment. Further research is needed to quantify contaminant loads and transfer pathways in these agricultural systems, and to better understand the threshold levels of contaminants that adversely affect plant health and which may result in devastating economic losses.

Influence of soil characteristics and agricultural practices on microplastic concentrations in sandy soils and their association with heavy metal contamination

Microplastics (MPs) seriously threaten soil quality and crop health, particularly in agricultural systems using plastic mulch and sewage sludge, with their abundance being strongly influenced by soil properties such as texture, structure, and chemical content. Considering this, the present study assessed MP contamination in arid agricultural soils, focusing on their abundance, morphology, composition, and association with heavy metals to evaluate environmental risks. Soil samples were collected from ten plastic-mulched fields and a control site across a 50 sq. km area. MPs were isolated using density separation and hydrogen peroxide digestion, with morphology categorized through microscopy and polymer composition analysed via FTIR. ICP-OES was used for elemental analysis. Statistical methods, including ANOVA, Pearson's correlation, scatter plots, and PCA, were applied to examine the influence of soil quality on MP levels. Results showed significantly higher MP concentrations in mulched fields (1412 ± 529 particles) compared to the control (72 ± 41 particles), with MPs primarily consisting of fibres, films, fragments, and microbeads. Positive correlations were observed between MPs and soil properties such as clay content, moisture, and organic matter content. FTIR analysis identified eight polymer types, while heavy metals, mainly Fe and Ni, were found to accumulate within MPs. MP counts were positively correlated with mulching duration (r2 = 0.46 to 0.94), indicating increased contamination over time. These findings emphasize the role of soil properties on MP retention and potential risks posed to soil health and environmental sustainability, stressing the need for strategies to mitigate MP contamination in agriculture.

Smallest microplastics intensify maize yield decline, soil processes and consequent global warming potential

Microplastic pollution seriously affects global agroecosystems, strongly influencing soil processes and crop growth. Microplastics impact could be size-dependent, yet relevant field experiments are scarce. We conducted a field experiment in a soil-maize agroecosystem to assess interactions between microplastic types and sizes. Microplastics were added to soils used for maize cultivation: either polyethylene or polystyrene, of 75, 150, or 300 µm size. Overall, we found that microplastic contamination led to increased soil carbon, nitrogen and biogeochemical cycling. Polyethylene contamination was generally more detrimental than polystyrene. Smallest polyethylene microplastics (75 µm) were associated with two-fold raised CO2 and N2O emissions - hypothetically via raised microbial metabolic rates. Increased net greenhouse gases emissions were calculated to raise soil global warming potential of soils. We infer that MPs-associated emissions arose from altered soil processes. Polyethylene of 75 µm size caused the greatest reduction in soil carbon and nitrogen pools (1-1.5 %), with lesser impacts of larger microplastics. These smallest polyethylene microplastics caused the greatest declines in maize productivity (∼ 2-fold), but had no significant impact on harvest index. Scanning electron microscopy indicated that microplastics were taken up by the roots of maize plants, then also translocated to stems and leaves. These results raise serious concerns for the impact of microplastics pollution on future soil bio-geochemical cycling, food security and climate change. As microplastics will progressively degrade to smaller sizes, the environmental and agricultural impacts of current microplastics contamination of soils could increase over time; exacerbating potential planetary boundary threats.

Factors Influencing the Vertical Migration of Microplastics up and down the Soil Profile

Soil ecosystems are under serious threat from microplastics (MPs), and this is causing worldwide concern. The relationship between soil and MPs has become a popular research topic, and the vertical migration of soil MPs is of increasing interest. This Review summarizes the current status of research into the factors affecting the vertical migration of soil MPs. Published research shows that the characteristics of MPs and the physicochemical properties of the soil affect the infiltration process. Soil organisms play a key role in the vertical migration by acting as vectors or as a result of adsorption. Dissolved organic matter and metal oxides transfer MPs by adsorption-desorption. In addition, rainfall and dry-wet cycles alter the mobility of soil MPs, leading to changes in migration processes. Agricultural activities such as tillage and irrigation may distribute MPs throughout the topsoil. Vertical migration of soil MPs is a process influenced by a combination of factors, and the role of these factors in MP deposition needs to be explored further.

Understanding the possible cellular responses in plants under micro(nano)-plastic (MNPs): Balancing the structural harmony with functions

The harmful impacts of micro(nano)-plastics (MNPs) on plants have gained significant attention in the last decades. Plants have a greater tendency to aggregate positively charged (+ve) MNPs on leaf surfaces and root tips, and it can be more challenging to enter the plant body than the negatively charged (-ve) MNPs. MNPs <20 nm can directly cross the cell wall and enter mainly via leaf stomata and root crack portion. Additionally, plants with aerenchyma tissue or higher water requirement might be more vulnerable to MNPs as well as environmental factors also affected MNPs uptake like porosity and structure (i.e. crack of soil) of soil, wind speed, etc. The subsequent translocation of MNPs hamper regular morphological, physiological, and biochemical functions by causing oxidative stress, altering several plant metabolic pathways, reducing the rate of photosynthesis and nutrient intake, etc. These induce cellular toxicity and chromosomal alteration; as a result, the total biomass and productivity reduce vigorously. However, there is a knowledge gap regarding MNPs' uptake by plants and related variables affecting phytotoxicity at the omics levels. So, the present literature review represents a comprehensive theoretical framework that includes genomics, transcriptomics, miRNAomics, proteomics, metabolomics, and ionomics/metallomics, which is established to understand the effects of MNPs on plants at the molecular level. As well as it will also help in further studies of the research community in the future because this field is still in the preliminary stages due to a lack of study.

Global soil microplastic assessment in different land-use systems is largely determined by the method of analysis: A meta-analysis

Although microplastics (1 μm - 5 mm, MP) are increasingly recognised as a novel entity of pollutants, we still lack a basic understanding of their prevalence in different terrestrial environments. Here, we aimed at performing comparisons of MP concentrations (items kg-1) in different agro-ecosystems, with specific focus on input pathways and land uses, while accounting for the plethora of method variations available, such as analysed MP sizes, sampling depths, density separation solutions, as well as removal of organic matter. We found that the current global means of MP loads, from 89 studies (553 sites), benchmarks 2900 ± 7600 MP items kg-1 soil, substantially more than the global median of 480 MP items kg-1. Roughly 81 % of the studies were conducted in Asia; hence, continent-wide comparisons are still hampered by low study numbers for most regions. Maximum MP numbers were found for soils under both greenhouses and plastic mulching (5200 ± 8300 items kg-1), followed by arable soils with sludge amendments (3700 ± 8800 items kg-1), surprisingly without evidence of elevated MP loads in horticultural fields relative to other agricultural management practices. Intriguingly, global MP loads significantly increased with decreasing levels of urbanisation, i.e., they were highest in rural areas. Yet, quantitative comparisons among sites are biased by the methodology selected for MP analyses. Apart from inconsistencies in sampling depth and size of screened MP particles, across all sites and treatments, largest MP loads were commonly found when using high-density solutions rather than low-density ones, and when soil organic matter removal was performed after, and not before, the density separation step.

The Adsorption Process and Mechanism of Benzo[a]pyrene in Agricultural Soil Mediated by Microplastics

The coexistence of microplastics and benzo[a]pyrene (BaP) in the environment, and their interactions within agricultural soils in particular, have garnered widespread attention. This study focused on the early-stage interactions between microplastics and BaP, aiming to uncover their initial adsorption mechanisms. Despite the significant environmental toxicity of both pollutants, research on their mutual interactions in soil is still limited. This study conducted adsorption thermodynamics and kinetics experiments to explore the effects and mechanisms of various microplastics (polyethylene (PE), polystyrene (PS), and polyvinyl chloride (PVC)) on the adsorption of BaP. Using advanced techniques such as scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared (FTIR) spectroscopy, this study explored the surface characteristics of microplastics and their interactions with BaP. The results demonstrated that PVC microplastics exhibited the highest adsorption capacity for BaP, which was primarily due to π-π interactions and increased hydrophobicity. In the soil-microplastic blend systems, BaP was predominantly found on microplastics, enhancing the soil's adsorption capacity for BaP, particularly PVC, which showed an adsorption capacity 3.69 times greater than that of soil alone. Density functional theory (DFT) simulation calculations indicated that the binding energy of BaP for PVC pretreated with soil was -59.16 kJ/mol, whereas it was -53.02 kJ/mol for untreated PVC, -39.35 kJ/mol for PE, and -48.84 kJ/mol for PS. These findings suggest that soil pretreatment enhances the adsorption stability of PVC for BaP, further elucidating the potential mechanisms behind the increased adsorption capacity in the soil-microplastic system. These findings confirm that microplastics serve as effective vectors for organic pollutants such as BaP, significantly influencing their environmental behavior in soils, and provide essential theoretical support for assessing the environmental toxicity and migration behaviors of microplastics and associated organic contaminants.

Effects of polystyrene microplastics on the growth and metabolism of highland barley seedlings based on LC-MS

Microplastics are widely present in the environment and can adversely affect plants. In this paper, the effects of different concentrations of microplastics on physiological indices and metabolites of highland barley were investigated for the first time using a metabolomics approach, and revealed the response mechanism of barley seedlings to polystyrene microplastics (PS-MPs) was revealed. The results showed that the aboveground biomass of highland barley exposed to low (10 mg/L) and medium (50 mg/L) concentrations of PS-MPs increased by 32.2% and 48.2%, respectively. The root length also increased by 16.4% and 21.6%, respectively. However, the aboveground biomass of highland barley exposed to high (100 mg/L) concentrations of PS-MPs decreased by 34.8%, leaf length by 20.7%, and root length by 25.9%. Microplastic exposure increased the levels of antioxidant activity, suggesting that highland barley responds to microplastic stress through oxidative stress. Metabolome analysis revealed that the contents of 4 metabolites increased significantly with increasing PS-MPs concentration in positive ionmode, while the contents of 8 metabolites increased significantly with increasing PS-MPs concentration in negative ionmode (P < 0.05), including prunin, dactylorhin E, and schisantherin B. Additionally, PS-MPs significantly interfered with highland barley flavonoid biosynthesis, pyrimidine metabolism, purine metabolism, fatty acid biosynthesis, and phenylpropanoid biosynthesis metabolic pathways. This study provides a new theoretical basis for a deeper understanding of the effects of different concentrations of PS-MPs on highland barley.

Assessing microplastics contamination and characteristics in organic soil amendments in the Greater Accra Metropolitan Area of Ghana

The study examines the increasing use of organic soil amendments (OSA) due to declining soil fertility and the high cost of synthetic fertilizers, alongside growing concerns about microplastics (MPs) accumulating in soil, which negatively impact soil, crop, and food quality. This research assessed the presence and characteristics of microplastics in Municipal Solid Waste Composts (MSWC) and dry sewage sludge (DSS) within the Greater Accra Metropolitan Area (GAMA) of Ghana. The study analyzed two sources of MSWC (MSWC 1 and MSWC 2) and two sources of DSS (Sludge 1 and Sludge 2), with five samples each, for microplastic concentrations. A reference soil sample, collected from a depth of 0-25 cm, was also tested. The microplastics were extracted using acid digestion (30 % H2O2 at 70 °C), density separation with a ZnCl2 solution, and vacuum filtration. Results revealed that Sludge 1 had the highest concentration of microplastics (4316 ± 968 MP kg-1), followed by MSWC 1 (3572 ± 1196 MP kg-1), MSWC 2 (3104 ± 418 MP kg-1), and Sludge 2 (2024 ± 562 MP kg-1). The soil sample had the lowest concentration of 232 ± 62 MP kg-1. Statistical analyses (Kruskal Wallis and Dunn's multiple comparisons) showed significant differences (p < 0.05) in microplastic concentrations among the samples. The composition of microplastic polymers varied among the samples. The soil sample predominantly contained cellophane (91.67 %) and polyvinyl propionate (8.33 %). MSWC 1 contained urethane alkyd (31.11 %), polyethylene (26.67 %), and polyester (20 %), while MSWC 2 had polyethylene (24.10 %), polyester (20.48 %), cellophane (18.07 %), and polypropylene (15.66 %). Sludge 1 was dominated by polyethylene (35.29 %), polypropylene (30.25 %), cellophane (15.13 %), and urethane alkyd (11.76 %), whereas Sludge 2 mainly contained polyester (42.86 %), cellophane (23.21 %), urethane alkyd (21.43 %), and polyethylene (12.50 %). Microplastics were prevalent in the MSWC and sewage sludge which were obtained from the GAMA, with significantly higher concentrations than those in the soil samples. Further research is needed to develop strategies to mitigate microplastic pollution in OSAs to improve soil health.

Characteristics of soil microplastics and ecological risks in the Qilian Mountains region, Northeast Tibetan Plateau

Microplastics (MPs) pollution has become a vital global environmental issue. However, comprehensive understanding of the ecological risks of MPs in soils of Northeast Tibetan Plateau still requires further study. In this study, we used the Agilent 8700 Laser Direct Infrared (LDIR) spectroscopy to analyze the characteristics of 10-1000 μm MPs in soils of different vegetation types throughout the Qilian Mountains basin, and to comprehensively explore the ecological risks of MPs in various ecological environments. The results indicate that MPs abundance is highest in soil of shrub areas (26,369 ± 32,147 items kg-1-dry weight (dw)), followed by woodland (22,215 ± 22,544 items kg-1-dw), desert (17,769 ± 9,040 items kg-1-dw), grassland (16,462 ± 12,872 items kg-1-dw), and forest (15,662 ± 13,857 items kg-1-dw). MPs in soils of different vegetation types show similar physical and chemical characteristics, with the shape dominated by fragments (93%-96%), followed by fibers and a few beads, with dominant sizes of 10-30 μm (63%-76%), and polymers dominated by polyamide (PA) and polyethylene terephthalate (PET). Additionally, the environmental risks posed by the fundamental characteristics of MPs have been quantified through the Pollution Load Index (PLI), Pollution Hazard Index (PHI), and Potential Ecological Risk Index (PERI) models. According to the PLI assessment, the current levels of MPs in the environment have not yet imposed significant burdens on the ecosystem. However, the results of PHI and PERI indicate a higher risk of MPs pollution in the Qilian Mountains. This study offers vital information for MPs pollution in the whole Qilian Mountains regions and their potential environmental risks in remote areas' soil.

Environmental fate of microplastics and common polymer additives in non-biodegradable plastic mulch applied agricultural soils

Numerous studies have been conducted to investigate the impact of microplastics on soil eco-system, yet little attention has been given to the specific effects of mulch microplastics and the leaching of plastic additives from mulch films. This review inspects the propensity of commonly used plastic additives in mulch films, such as Di(2-ethylhexyl) phthalate (DEHP), bisphenol A (BPA), and benzophenones (BPs), to migrate into soils and pose potential risks to soil biota. Further, we highlight the degradation of non-biodegradable plastic mulch films over time, which leads to an increase in the release of plastic additives and microplastics into agricultural soils. DEHP has been detected in high concentrations for example 25.2 mg/kg in agricultural soils, indicating a potential risk of uptake, translocation and accumulation in plants, ultimately altering soil physicochemical properties and affecting soil microflora and invertebrates. The review also explores how exposure to ultraviolet (UV) radiation and microbial activities accelerates the weathering of mulch films. Moreover, the resultant plastic additives and mulch microplastics can lead to genotoxicity and growth inhibition in earthworms (Eisenia fetida) and negatively impact the soil microbiome. Despite the significant implications, there has been a lack of comprehensive reviews comparing the effects of non-biodegradable mulch film additives on agricultural soil flora and fauna. Therefore, this review addresses the knowledge gaps providing a bibliometric analysis and eco-toxicological evaluation, discussing the challenges and future perspectives regarding mulch plastic additives and microplastics, thus offering a comprehensive understanding of their impact.

Mitigating the effects of polyethylene microplastics on Pisum sativum L. quality by applying microplastics-degrading bacteria: A field study

Polyethylene microplastics (PE-MPs) have been widely reported for their adverse effects on soil ecosystems. However, there are fewer field studies on addressing PE-MPs contamination in soil. This study investigated the effects of PE-MPs on soil properties, rhizosphere soil microorganisms, and pea (Pisum sativum L.) nutrient composition in a field experiment and mitigated the effects of PE-MPs by adding MPs-degrading bacteria. The results showed that the addition of MPs-degrading bacteria mitigated the effects of PE-MPs on the hydrolyzable nitrogen content in the soil. In addition, the introduction of MPs-degrading bacteria resulted in an increase in the Shannon indices of microorganisms in the soil. This also effectively regulates the structure of the soil microbial community to be closest to that of normal soil. Notably, the addition of MPs-degrading bacteria increased the protein, starch, cellulose, and chlorophyll contents of pea grains. This study demonstrated the ability to improve the nutrient content of peas affected by MPs by adding MPs-degrading bacteria. This study contributes to our understanding of the effects of PE-MPs on soil-microbe-plant systems and provides new insights into the bioremediation of PE-MPs in agricultural soils.

Microplastics as an Emerging Potential Threat: Toxicity, Life Cycle Assessment, and Management

The pervasiveness of microplastics (MPs) in terrestrial and aquatic ecosystems has become a significant environmental concern in recent years. Because of their slow rate of disposal, MPs are ubiquitous in the environment. As a consequence of indiscriminate use, landfill deposits, and inadequate recycling methods, MP production and environmental accumulation are expanding at an alarming rate, resulting in a range of economic, social, and environmental repercussions. Aquatic organisms, including fish and various crustaceans, consume MPs, which are ultimately consumed by humans at the tertiary level of the food chain. Blocking the digestive tracts, disrupting digestive behavior, and ultimately reducing the reproductive growth of entire living organisms are all consequences of this phenomenon. In order to assess the potential environmental impacts and the resources required for the life of a plastic product, the importance of life cycle assessment (LCA) and circularity is underscored. MPs-related ecosystem degradation has not yet been adequately incorporated into LCA, a tool for evaluating the environmental performance of product and technology life cycles. It is a technique that is designed to quantify the environmental effects of a product from its inception to its demise, and it is frequently employed in the context of plastics. The control of MPs is necessary due to the growing concern that MPs pose as a newly emergent potential threat. This is due to the consequences of their use. This paper provides a critical analysis of the formation, distribution, and methods used for detecting MPs. The effects of MPs on ecosystems and human health are also discussed, which posed a great challenge to conduct an LCA related to MPs. The socio-economic impacts of MPs and their management are also discussed. This paper paves the way for understanding the ecotoxicological impacts of the emerging MP threat and their associated issues to LCA and limits the environmental impact of plastic.

Distribution of microplastics in the soils of a petrochemical industrial region in China: Ecological and Human Health Risks

Although microplastic pollution is a global concern, information on the distribution of microplastics in petroleum and petrochemical urban soils is limited. In this study, we investigated the occurrence, ecological risk, and human exposure risk of microplastics in different land-use types of soil in Daqing Administrative region, a prominent petroleum and petrochemical industrial base in China. Stereoscopic microscopy and Fourier transform infrared spectroscopy (μ-FTIR) were used to study the chemical composition and distribution characteristics of microplastics. We found that the abundance of microplastics in Daqing soil ranged from 714 to 11,122 items/kg, with the highest value in educational land and the lowest in parks and green land. The dominant particle size of microplastics was < 1 mm (65.7%), and the shape was mainly fiber (55.1%), with white (28.9%) and black (25.6%) as the predominant colors. The most common polymer types were rayon, polypropylene, and polyethylene. Using the potential ecological risk index (RI) and polymeric risk index (H), we found that all land-use types, except woodland (Level I), were classified into Level V of ecological risk, with the highest risk in industrial land (RI = 14,959.85, H = 588.31). The daily exposure of infants to microplastics was much higher than that of adults. These findings provide valuable data for the pollution and potential risk assessment of microplastics in urban and rural environments, suggesting the importance of taking action to minimize its harmful effects on ecological and human health. In order to control the pollution caused by microplastics, we suggest that people should reduce the unnecessary use of single-use plastic items, such as water bottles, plastic shopping bags, straws, etc. In addition, the government needs to strengthen rubbish collection to prevent plastic waste from leaking into the environment during the period from the rubbish bins to the landfills, and to build recycling systems to increase the recycling rate.

Utilization of AI - reshaping the future of food safety, agriculture and food security - a critical review

Artificial intelligence is an emerging technology which harbors a suite of mechanisms that have the potential to be leveraged for reaping value across multiple domains. Lately, there is an increased interest in embracing applications associated with Artificial Intelligence to positively contribute to food safety. These applications such as machine learning, computer vision, predictive analytics algorithms, sensor networks, robotic inspection systems, and supply chain optimization tools have been established to contribute to several domains of food safety such as early warning of outbreaks, risk prediction, detection and identification of food associated pathogens. Simultaneously, the ambition toward establishing a sustainable food system has motivated the adoption of cutting-edge technologies such as Artificial Intelligence to strengthen food security. Given the myriad challenges confronting stakeholders in their endeavors to safeguard food security, Artificial Intelligence emerges as a promising tool capable of crafting holistic management strategies for food security. This entails maximizing crop yields, mitigating losses, and trimming operational expenses. AI models present notable benefits in efficiency, precision, uniformity, automation, pattern identification, accessibility, and scalability for food security endeavors. The escalation in the global trend for adopting alternative protein sources such as edible insects and microalgae as a sustainable food source reflects a growing recognition of the need for sustainable and resilient food systems to address the challenges of population growth, environmental degradation, and food insecurity. Artificial Intelligence offers a range of capabilities to enhance food safety in the production and consumption of alternative proteins like microalgae and edible insects, contributing to a sustainable and secure food system.

Comparative evaluation of the impacts of different microplastics on greenhouse gas emissions, microbial community structure, and ecosystem multifunctionality in paddy soil

Although the increasing accumulation of microplastics (MPs) in terrestrial soil ecosystems has aroused worldwide concern, research remains limited on their potential impacts on soil processes and ecosystem functionality. Here, through a 41-day microcosm experiment, we found that polylactic acid (PLA), low-density polyethylene (LDPE), and polypropylene (PP) MPs consistently increased soil carbon nutrients and pH but had varying effects on soil nitrogen nutrients and the chemodiversity of dissolved organic matter (DOM). Different treatments led to notable shifts in the α-diversity and composition of soil microbial community, with phyla Proteobacteria and Ascomycota consistently enriched by MPs regardless of polymer type. The emissions of CO2 and N2O were suppressed by MPs in most cases, which in combination led to a decline in global warming potential. LDPE and 1 - 1.5 % of PLA MPs significantly improved the multifunctionality of the soil ecosystem, while PP and 0.5 % of PLA MPs exerted an opposite effect. Soil total organic carbon, pH, DOM molecular mass and condensation degree, and CO2 emissions were identified as the most important variables for predicting soil ecosystem multifunctionality. Results of this study can extend the current understanding of the impacts of MPs on soil biogeochemical cycling and ecosystem functionality.

Accumulation characteristics and source analysis of microplastics derived traffic of soil in the Tibetan Plateau

The development of transportation infrastructure can stimulate economic growth. However, the environmental and human health risks associated with the release of traffic-derived microplastics (MPs) into the ecosystem must also be considered. This study examined four types of soil samples collected from the Qinghai-Tibetan Plateau along the Gemang Highway. The abundance, size, morphology, and types of MPs were analyzed using laser direct infrared (LDIR) spectroscopy to gain a better understanding of their distribution and characteristics. The average abundance of MPs in the study area was 2247.92 ± 2053.82 n/kg. It showed the characteristics of wasteland (4726.67 ± 2956.76 n/kg) > wolfberry plantation (3294.44 ± 2881.93 n/kg) > sandy land (1519.44 ± 282.65 n/kg) > soil along the highway (1144.44 ± 611.01 n/kg). 67.25 % of MPs had a particle size of less than 100 µm, posing greater environmental risks. The 6 factors identified by the PMF model suggested a variety of potential sources of MPs and highlighted their connections to the transportation sector. The ecological risk assessment of MPs demonstrated a significant degree of risk, with particular concern regarding more toxic plastics use. This study provides fundamental data for the source analysis and ecosystem risk assessment of MPs derived traffic.

Microplastic accumulation and transport in agricultural soils with long-term sewage sludge amendments

Land application of sewage sludge brings microplastic contamination to soil. However, studies regarding the occurrence and mobility of sludge-borne microplastics in soil are insufficient. In the present study, based on an experimental field, the effects of sludge application amount on the accumulation and migration of microplastics in 0-20 (upper) and 20-40 cm (lower) soil layers were evaluated. After 16 years of continuous sludge application (36 t/ha per year), the microplastic content and migration ratio in upper soil reached 6811 particles/kg and 148 %, which was about 5 and 20 times, respectively, higher than that of the control soil without sludge. The microplastics in upper and lower soil layers, were mainly 0.2-0.5 mm in size, mostly fibrous in shape, primarily transparent in color, and predominantly rayon in composition. Microplastic surfaces may persistently adsorb clay minerals and iron/titanium oxides from soil, posing potential environmental risks. Sludge application had a significant positive correlation with soil microplastic abundance, resulting in a good fit of predictive model constructed for microplastic accumulation in sludge-amended soils. These findings help to improve the knowledge on environmental behavior of microplastics in sludge-amended soil, and can provide a scientific basis for the regulation of microplastic pollution during sludge land application.

Occurrence characteristics and ecological impact of agricultural soil microplastics in the Qinghai Tibetan Plateau, China

Plastic mulch is widely recognized as a significant contributor to microplastics (MPs) pollution in agricultural soil. However, its direct impact on remote areas with low population density remains uncertain due to multiple pollution sources. This study aims to investigate MPs pollution and its risks regarding agricultural soil in the Qinghai Tibetan Plateau (QTP) in China. The results revealed that soil samples from the study area exhibited a range of MPs abundance, varying from 16.67 to 950 items/kg, with the highest average abundance observed in Chengguan district (CG) soil samples (611.11 items/kg). Polyethylene terephthalate (PET), polypropylene (PP), and polyethylene (PE) were identified as the predominant components of MPs in farmland soil. Furthermore, significantly higher levels of MPs were found in the facility agriculture soil compared to the control soil. Diversity and risk of MPs in different regions and cultivation conditions were significantly different. According to the employed risk assessment models, agricultural soil demonstrated a relatively high polymer risk (47 % of areas classified as level III). In addition to being influenced by exogenous factors, the diversity of MPs also plays an intrinsic role in regulating the risk of MPs pollution. This study contributes to an enhanced comprehension of the issue of MPs pollution in QTP farmland soil, providing valuable empirical evidence and theoretical underpinning for the development of efficacious control strategies.

Spatial distribution and impacts of microplastics on potato growth and yield in agroecosystems in Sialkot, Pakistan

Microplastic (MP) pollution is a growing concern, yet its impacts on agroecosystems remain poorly understood. This study investigates MP contamination in the agroecosystems of Sialkot, Pakistan, and its potential effects on the growth, physio-biochemical attributes, and yield of potato (Solanum tuberosum L.). Plant and soil samples from 10 diverse agricultural fields were collected and analyzed for MP contamination. FTIR analysis revealed widespread MP presence in the soil across all sites. Fragment, film, and fiber types dominated, with low-density polyethylene (22.42 %), high-density polyethylene (18.05 %), and polystyrene (12.3 %) being the most prevalent polymers. A significant variation in plant growth parameters was observed. The number of tubers per plant also exhibited a significant difference, as evidenced by the decline in potato yield with increasing levels of MP contamination. Potato yield showed a negative correlation with MP contamination levels. The nutrients (Zn, Cu, Ni, and Na) uptake in plant shoots was also observed to be decreased except for Mg and Mn at all sites. This study showed that MPs are contaminating our agricultural lands and they may affect growth and yield of potato. Additional research is needed to understand the underlying mechanisms and develop mitigation strategies to improve agricultural productivity and food security.

Microplastic and antibiotics in waters: Interactions and environmental risks

Antibiotics (ATs) are ubiquitously detected in natural waters worldwide, and their tendency to co-migrate with microplastics (MPs) post-adsorption leads to heightened environmental risk. Research on the adsorption of ATs on MPs and their subsequent effects on the environmental risks is gaining significant attention globally. This adsorption process predominantly occurs through hydrophobic forces, hydrogen bonds, and electrostatic interactions and is influenced by various environmental factors. The interaction between MPs and ATs exhibited varying degrees of efficiency across different pH levels and ionic strengths. Furthermore, this paper outlines the environmental risks associated with the co-presence of MPs and ATs in aquatic environments, emphasizing the potential effect of MPs on the distribution of antibiotic resistance genes (ARGs) and related environmental risks. The potential hazards posed by MPs and ATs in aquatic systems warrant serious consideration. Future research should concentrate on the adsorption of ATs/ARGs on MPs under real environmental conditions, horizontal gene transfer on MPs, as well as biofilm formation and agglomeration behavior on MPs that needs to be emphasized.

Microplastic migration from landfill-mined soil through earth filling operations and ecological risk assessment: a case study in New Delhi, India

Microplastics (MPs), plastic pieces smaller than 5 mm, are emerging as a critical ecological threat, potentially disrupting ecosystems and complicating waste management practices. Landfill-Mined Soil-Like Material (LMSLM), a byproduct of landfill reclamation, is gaining global traction for rehabilitating degraded land and repurposing it for geotechnical applications. While studies have examined contaminants like heavy metals and salts, MPs contamination has been largely overlooked, raising environmental concerns. The widespread use of LMSLM in earth-filling increases the risk of MP pollution. Additionally, significant gaps remain in understanding how MPs are distributed across different size fractions during sieving, which is critical for developing effective remediation strategies and informing future policies. This study aims to fill the existing knowledge gap by investigating the presence of microplastics in LMSLM collected from three aged waste dumpsites in New Delhi, India, and evaluating the ecological risks associated with its reuse. The results revealed the presence of MPs in all LMSLM samples with concentrations ranging from 25950 to 41110 items/kg. Fibers and fragments were the dominant shapes, with 60 % of particles measuring less than 425 µm. The color characteristics revealed the dominance of white, transparent, and black color. Polyethylene and polypropylene were the most common polymers, with smaller amounts of polyamide, polyethylene terephthalate, and polyester. SEM-EDX analysis revealed weathering effects and the presence of heavy metals, including Lead (Pb), Cadmium (Cd), and Arsenic (As), adsorbed on the MP surface. Ecological risk assessment using the Polymer Hazard Index and Pollution Load Index identified hazard levels of V and II, respectively, while the Potential Ecological Risk Index indicated a medium risk. Furthermore, the dimensional analysis demonstrates that MP width, particularly in fiber-shaped MPs, plays a crucial role in determining retention and migration during sieving, while MPs with uniform shapes, like spheres and fragments, exhibit limited movement. These findings underscore the need for protective measures when using LMSLM in geotechnical applications to prevent MP migration and contamination of surrounding environments. The study highlights the importance of further research on MP contamination in reclaimed landfill materials and its implications for sustainable land use and waste management.

Microplastics in soil: A comprehensive review of occurrence, sources, fate, analytical techniques and potential impacts

Through their accumulation in soils, microplastics have recently become a matter of concern. The aim of this review is to assemble and investigate the recent studies about microplastics in soil by focusing on their sources, occurrence, fate in soil, and analytical methods. The objective is also to clarify and elucidate their potential impacts on soil fauna, plants and microorganisms. In this paper, articles reporting the quantity of microplastics and their characteristics in soil at 62 sites situated across 17 countries were reviewed. The land type, microplastic abundances, types and sizes were compared. We summarized and discussed the sampling and analytical methods used and the variation of microplastic concentration according to their sources. The data showed that microplastic in soil from available global studies ranged from 0 to 3573×103 particles kg-1, with major dominance of polyethylene, polystyrene and polypropylene found in 50, 37 and 32 studies, respectively. The data analysis showed the high migration of small particles, spherical shape with high polymer density in the major studies. We also described the mechanisms controlling the vertical transport of microplastics: agricultural activity (plowing: at a depth between 10 cm (very shallow plowing) and 40 cm (deeper soil tillage)), bioturbation by soil organisms and plants, and leaching that can lead to the contamination of the groundwater. This review elucidated the behavior and fate of microplastics within the soil, serving as a reference for upcoming studies aimed at devising solutions to mitigate the toxicity associated with microplastics in soil.

Delving into South China Sea microplastic pollution: Abundance, composition, and environmental risk

Understanding marine pollution in the South China Sea is crucial for preserving marine ecosystems and biodiversity. Despite extensive research on pollutants, there is a significant gap in knowledge about microplastics (MPs) in the archipelago region. This study focused on four typical islands, examining MPs in seawater and sediments, their distribution, and environmental risks. Most MPs (>90 %) were smaller than 2.5 mm, with black fiber-shaped polyethylene terephthalate MPs being predominant. MPs in seawater had lower abundance (5-12 items/L) compared to sediment (100-2600 items/kg) but showed richer polymer composition. Pollution load index (PLI) and risk index analysis indicated all regions were contaminated (PLI > 1), with the Zhongsha islands being the most polluted. Correlation analysis highlighted black, fibrous PET-like polymers with large particle sizes (>0.5 mm) as major contributors. This study could help to understand the MPs distribution and pollution in the archipelago region of the South China Sea.

Polystyrene influence on Pb bioavailability and rhizosphere toxicity: Challenges for ramie (Boehmeria nivea L.) in soil phytoremediation

Microplastics (MPs) and heavy metals often coexist in soil, however their interactions and effects on the soil-plant system remain largely unclear. In this study, ramie (Boehmeria nivea L.) was exposed to soil contaminated with lead (Pb) and polystyrene (PS) of different sizes, dosages, and surface-charged functional groups. This design aimed to simulate the effects of MPs on phytoremediation. The experimental results revealed that PS exacerbated the damaging effects of Pb on ramie. Compared to the effect of Pb alone, PS-COOH had a greater influence on root vigor, leading to a 15.6 % reduction in the active absorption ratio. Laser scanning confocal microscope showed PS entered the roots. Adsorption/desorption experiments demonstrated that PS had a weaker adsorption capacity for Pb than soil but a greater desorption rate than soil when simulating rhizosphere secretion. Moreover, PS reduced soil pH and increased the reducible state of Pb by 6-12 %. After 100 days of phytoremediation, Pb content in the soil with PS-5 μm was 150 μg g-1 less than that in the soil without PS. These results demonstrated that PS improved Pb bioavailability and enhanced the efficiency of Pb uptake by ramie. The redundancy analysis demonstrated that PS mitigated the toxicity of Pb to rhizosphere microorganisms, potentially via its effects on metal chemical fractions, dehydrogenase activity (S-DHA), cation exchange capacity (CEC), and soil organic matter (SOM). This study indicates that the presence of PS could potentially enhance the phytoremediation efficiency of ramie in Pb-contaminated land by influencing soil microenvironmental properties. This study provides insights into the complex interactions of MPs with soil-plant-microbial systems during metal remediation, thereby enhancing our understanding of their environmental impacts.

Seabirds as biovectors in the transport of plastic debris across ecosystem borders: A case study from the Humboldt Current Upwelling System

Seabirds have become biovectors of plastic pollutants between marine and terrestrial ecosystems, and transport of plastics to their nesting sites becomes relevant due to increasing levels of pollution. To determine the pathways by which plastic reaches their colonies, we analysed the abundance of plastics at the nesting sites of five seabird species (Humboldt penguin Spheniscus humboldti, Peruvian booby Sula variegata, kelp gull Larus dominicanus, grey gull Leucophaeus modestus, Markham's storm-petrel Hydrobates markhami) nesting in northern Chile. Seabirds were primarily grouped according to their nesting behaviour, but two species foraging in contrasting habitats (kelp gull and Markham's storm-petrel) were also compared directly. The abundance, type, and polymer of macro-, meso- and microplastics were analysed in the soil of colonies and control sites, and microplastic ingestion was evaluated for selected species. Densities of plastics in colonies of surface-nesting seabirds ranged from 0 to 21.4 items m-2 (mainly plastic bags and thin films), and 0.002 to 19.7 items m-2 (mainly hard fragments) in colonies of burrow-nesting seabirds. Mean microplastic loads in the stomachs of seabirds were between 3.7 ± 4.2 plastic items individual-1. Overall, the abundances of plastic items in all seabird colonies were low, suggesting a limited transfer of plastics from sea to land. For kelp gulls, the results indicate transfer of macroplastic items to colonies, reaching the colony via regurgitates, with landfills considered as the main plastic source. Our results suggest that contrasting nesting behaviour and foraging habitats among species can explain differential plastic accumulation in seabird colonies, but also other factors, such as wind, contribute to the accumulation of plastic debris in colonies. Proper management of sanitary landfills are key to reduce plastic contamination of coastal seabirds and their colonies.

Distribution, characteristics, and ecological risks of microplastics in the Hongyingzi sorghum production base in China

Microplastics (MPs), an emerging pollutant of global concern, have been studied in the Hongyingzi sorghum production base. In this study, we investigated MPs in the surface soil (0-10 cm) and deeper soil (10-20 cm) in the Hongyingzi sorghum production base. Pollution characterization and ecological risk evaluation were conducted. The results revealed that the MP abundance ranged from 1.31 × 102 to 4.27 × 103 particles/kg, with an average of 1.42 ± 1.22 × 103 particles/kg. There was no clear correlation between the MP abundance and soil depth, and the ordinary kriging method predicted a range of 1.26 × 103-1.28 × 103 particles/kg in most of the study area, indicating a relatively uniform distribution. Among the 12 types of MPs detected, acrylates copolymer (ACR), polypropylene (PP), polyurethane (PU), and polymethyl methacrylate (PMMA) were the most frequently detected. These MPs primarily originated from packaging and advertising materials made from polyurethane and polyester used by Sauce Wine enterprises, as well as plastic products made from polyolefin used in daily life and agricultural activities. The particle size of MPs was primarily 20-100 μm. Overall, the proportion of the 20-100 μm MP was 95.1% in the surface soil layer and 86.7% in the deeper soil layer. Based on the pollution load index, the MP pollution level in the study area was classified as class I. Polymer hazard index evaluation revealed that the risk levels at all of the sampling sites ranged from IV to V, and ACR, PU, and PMMA were identified as significant sources of polymer hazard. Potential ecological index evaluation revealed that most of the soil samples collected from the study area were dangerous or extremely dangerous, and the surface soil posed a greater ecological risk than the deeper soil. These findings provide a scientific foundation for the prevention, control, and management of MP pollution in the Hongyingzi sorghum production base.

Microplastic pollution unveiled: the consequences of small unregulated dumping in villages, spanning from soil to water

Microplastic contamination in soil ecosystems is a major environmental concern in the world. The current study aims to explore the extent of microplastic pollution in unregulated village dumpsites in India, focusing on the movement of these pollutants from soil to aquatic environments. Soil samples from eight distinct sites (A to H) in six villages were analyzed for various properties, including pH, bulk density, porosity, water retention capacity, hydraulic conductivity, and particle size distribution. The attenuated total reflection-Fourier-transform infrared spectroscopy (ATR-FTIR) method was used to identify prevalent plastic types. The research classifies microplastics by their shape and color, identifying a wide range of particles such as sheets, fibers, foams, fragments, and films. The study also examines the presence and concentration of microplastics in both soil and sediment samples. It was found that PE and PP microplastics are significantly present across different size fractions. Sample A contains a variety of items in the 1-5 mm size range, mainly PE, while the 0.3-1 mm fraction is largely PP. Samples B to H are mostly composed of PE microplastics in different forms. Sample F is unique with a mix of PE, EPS, and a higher amount of red and blue foam particles in the 0.3-1 mm fraction. Microplastics were quantified using stereomicroscopy, revealing concentrations between 80 and 840 numbers per kilogram in soil and 20 to 60 numbers per kilogram in sediments. The findings emphasize the widespread nature of microplastic pollution across ecosystems and the importance of developing effective strategies for monitoring and mitigating their impact on environmental health and human well-being.

Characterization of microplastics in soil, leachate and groundwater at a municipal landfill in Rayong Province, Thailand

Recent years have witnessed a dramatic increase in global plastic production, leading to heightened concerns over microplastics (MPs) contamination as a significant environmental challenge. MP particles are ubiquitously distributed across both continental and marine ecosystems. Given the paucity of research on MPs in Thailand, particularly regarding MPs contamination in terrestrial environments, this study focused on investigating the distribution and characteristics of MPs in a landfill area. We collected 15 soil samples, 2 leachate samples, and 7 groundwater samples from both inside and outside a municipal landfill situated in the urbanized coastal region of Rayong Province. Our findings revealed variability in MPs concentration across different sample types. In soil, the MP count ranged from 240 to 26,100 pieces per kg of dry soil, 58.71 % of all sample sizes are lower than 0.5 mm. Similarly, the size found in the leachate sample, and the average MP in the leachate samples was 139 pieces per liter of MPs. The groundwater samples showed a fluctuation in MPs count from 18 to 94 pieces per liter, and the size of MPs ranged mostly from 0.5 to 1 mm. The predominant forms of MPs identified were sheets, followed by fragments, fibers, and granules. According to μ-FTIR analysis, the majority of the MPs were composed of polyethylene and polypropylene, commonly used in plastic packaging and ropes. The observed high concentrations and extensive distribution of MP contamination underscore the urgency for further studies and effective management strategies to mitigate the adverse impacts of this pollution on various organisms and ecosystems.

Decreased Sulfamethoxazole Uptake in Lettuce (Lactuca sativa L.) due to Transpiration Inhibition by Polypropylene Microplastics

Microplastics and antibiotics are emerging contaminants in agricultural soil that can have negative effects on crops. However, limited research has been conducted on the effects of the polypropylene (PP) microplastic and sulfamethoxazole (SMX) co-exposure on crops, specifically regarding the impact of PP microplastics on SMX uptake and transport in crops. In this study, hydroponic experiments were carried out using lettuce (Lactuca sativa L.), PP microplastics (1.0 g L-1), and SMX (0.5 mg L-1 or 2.5 mg L-1) to investigate the individual and co-exposure effects of PP microplastics and SMX on Lettuce growth, explore the uptake and translocation of SMX in lettuce and elucidate the underlying mechanism of PP microplastic impact on SMX uptake. Results demonstrated that co-exposure to 1.0 g L-1 of PP microplastics and 0.5 mg L-1 of SMX resulted in an enhanced toxic effect. However, no intensified toxic effect on the lettuce was observed when 1.0 g L-1 PP microplastics were added in the presence of 2.5 mg L-1 SMX, indicating that the SMX dominated the toxic effect on lettuce at high concentrations. Additionally, the study found that the water absorption process controlled by the aquaporin and transpiration contributed to the uptake and translocation of SMX in lettuce. When exposed to PP microplastics, no impact was observed on the aquaporin contents of the lettuce while the transpiration rate was significantly decreased by 31.6 % - 44.2 % resulting from microplastics adhered to the root surface. Therefore, in the presence of 2.5 mg L-1 SMX, the SMX uptake in the lettuce root was inhibited by 35.9 % (P < 0.05) when exposed to 1.0 g L-1 PP microplastic. This work deepens our understanding of the behaviour of microplastics and antibiotics in the terrestrial environment.

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.