Pollution Characteristics of Microplastics in Soils in Southeastern Suburbs of Baoding City, China

Polystyrene microplastics enhanced the toxicity of cadmium to rice seedlings: Evidence from rice growth, physiology, and element metabolism

Microplastics (MPs) and cadmium (Cd) are toxic to rice; however, the effects and mechanisms of their combined exposure are unclear. The combined exposure effects of polystyrene microplastics (PS-MPs) with different particle sizes (1-10 μm, 50-150 μm) and concentrations (50, 500 mg·L-1) and Cd on rice were explored. PS-MPs combined with Cd amplifies the inhibition of each individual exposure on the height and biomass of rice seedlings, and they showed antagonistic effects. PS-MPs reduced the content of chlorophyll and increased the content of carotenoid rice seedlings significantly. High concentrations of PS-MPs enhanced the inhibition of Cd on chlorophyll content. Cd, PS-MPs single and combined exposures significantly altered the antioxidant enzyme (POD, CAT, SOD) activities in rice seedlings. Under PS-MPs exposure, overall, the MDA content in shoots and roots exhibited opposite trends, with a decrease in the former and an increase in the latter. In comparison with Cd treatment, the combined exposures' shoot and root MDA content was reduced. Cd and PS-MPs showed "low concentration antagonism, high concentration synergism" on the composite physiological indexes of rice seedlings. PS-MPs significantly increased the Cd accumulation in shoots. PS-MPs promoted the root absorption of Cd at 50 mg·L-1 while inhibited at 500 mg·L-1. Cd and PS-MPs treatments interfered with the balance of microelements (Mn, Zn, Fe, Cu, B, Mo) and macroelements (S, P, K, Mg, Ca) in rice seedlings; Mn was significantly inhibited. PS-MPs can enhance of Cd's toxicity to rice seedlings. The combined toxic effects of the two contaminants appear to be antagonistic or synergistic, relying on the particle size and concentration of the PS-MPs. Our findings offer information to help people understanding the combined toxicity of Cd and MPs on crops.

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 laser diffuse reflectance 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 and polyethylene terephthalate. 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 Mountain regions and their potential environmental risks in remote areas' soil.

Characteristics, sources and potential ecological risk of atmospheric microplastics in Lhasa city

Atmospheric microplastics are important contributors to environmental contamination in aquatic and terrestrial systems and pose potential ecological risks. However, studies on atmospheric microplastics are still limited in urban regions of the Tibetan Plateau, a sentinel region for climate and environmental change under a warming climate. In this study, the occurrence and potential ecological risk of atmospheric microplastics were investigated in samples of suspended atmospheric microplastics collected in Lhasa city during the Tibetan New Year in February 2023. The results show that the average abundance of atmospheric microplastics in Lhasa was 7.15 ± 2.46 MPs m-3. The sizes of the detected microplastics ranged from 20.34 to 297.18 μm, approximately 87% of which were smaller than 100 μm. Fragmented microplastics (95.76%) were the dominant shape, followed by fibres (3.75%) and pellets (0.49%). The primary polymer chemical components identified were polyamide (68.73%) and polystyrene (16.61%). The analysis of meteorological data and the backwards trajectory model indicated the air mass in Lhasa mainly controlled by westwards, and the atmospheric microplastics mainly originated from long-distance atmospheric transport. The potential ecological risk index assessment revealed that the atmospheric microplastic pollution in Lhasa was relatively low. This study provides valuable insights and a scientific foundation for future research on the prevention and control of atmospheric microplastic pollution in Lhasa and other ecologically sensitive cities.

Extractability and phytotoxicity of heavy metals and essential elements from plastics in soil solutions and root exudates

Plastic waste is increasing and is a serious environmental problem. Among the threats associated with plastics is the release of contaminants into the environment. This study aimed to evaluate the efficiency of metals release from plastics (low-density polyethylene (LDPE), polyethylene terephthalate (PET), and polypropylene (PP)) as affected by different soil solution types, artificial root exudates, and distilled water. The extent of metal release varied depending on the type of solution and plastic used. Metals were leached most effectively from plastics in soil solutions, followed by root exudates, and least effectively by distilled water. LDPE released the highest concentrations of Cu and Na into solution, PP released the greatest amount of Fe, and PET released the most Cr. The efficiencies of Mg and Zn release from the plastics (PP and PET) varied by solution type. Among the plastics studied, LDPE exhibited the strongest ability to adsorb metals, such as Fe, Cr, Mg, and Zn from soil solutions. The amount of metal released from the plastics was also dependent on pH, dissolved organic carbon (DOC) concentrations, and the electrical conductivity (EC) of the solutions. Moreover, plastic extracts were found to have negative effects on germination and growth in Lepidium sativum.

Analytical challenges in detecting microplastics and nanoplastics in soil-plant systems

Microplastics (MPx) and nanoplastics (NPx) are increasingly accumulating in terrestrial ecosystems, heightening concerns about their potential adverse effects on human health via the food chain. Techniques aimed at recovering the most challenging colloidal fractions of MPx and NPx, especially for analytical purposes, are limited. This systematic review emphasises the absence of a universal, efficient, and cost-effective analytical method as the primary hindrance to studying MPx and NPx in soil and plant samples. The study reveals that several methods, including density separation, organic matter removal, and filtration, are utilized to detect MPx or NPx in soil through vibrational spectroscopy and visual identification. Instruments such as Pyrolysis Gas Chromatography Mass Spectrometry (Py-GCMS), Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), Fourier Transform Infrared (FTIR) Spectroscopy, and fluorescence microscopy are employed to identify MPx and NPx in plant tissue. In extraction procedures, organic solvents and sonication are used to isolate NPx from plant tissues, while Pyrolysis GC-MS quantifies the plastics. SEM and TEM serve to observe and characterize NPx within plant tissues. Additionally, FTIR and fluorescence microscopy are utilized to identify polymers of MPx and NPx based on their spectral characteristics and fluorescence signals. The findings from this review clarify the identification and quantification methods for MPx and NPx in soil and plant systems and provide a comprehensive methodology for assessing MPx/NPx in the environment.

Sub-micron microplastics affect nitrogen cycling by altering microbial abundance and activities in a soil-legume system

Recently, the environmental and agricultural impact of plastic waste has attracted considerable attention. Here, we investigated the impact of sub-micron polyethylene (PE) and polypropylene (PP) microplastics (MPs) on nitrogen cycling, with emphasis on bacterial abundance and diversity in a soil-soybean (Glycine max) system. Exposure to soil containing MPs (50 and 500 mg kg-1) did not affect soybean growth, but significantly increased plant nitrogen uptake, which was confirmed by increased activities of nitrogenase in the soil and glutamine synthetase in soybean root. Additionally, there was an increase in 16S gene copy number and carbon and nitrogen substrate utilization, indicating increased abundance and activity of rhizosphere microbial communities. Moreover, MP contamination affected the taxonomic profile of rhizosphere bacteria, especially the abundance of symbiotic and free-living bacteria involved in nitrogen cycling. Furthermore, qPCR analysis of nitrogen-related genes and Kyoto Encyclopedia of Genes and Genomes analysis of 16S rRNA gene sequencing data revealed an increased abundance of functional genes associated with nitrogen fixation and nitrification. However, the concentration and polymer type of MPs did not have a significant impact in our system. Overall, these results provide insights into the interactions between MPs and rhizosphere bacterial communities in the soil-legume system.

Effects of microplastic type on growth and physiology of soil crops: Implications for farmland yield and food quality

Microplastic residues pose one of the most serious environmental problems in areas where plastic mulch is used extensively. Microplastic pollution has potentially serious consequences for ecosystems and human health. Several studies have analyzed microplastics in greenhouses or laboratory climate-controlled chambers; however, field studies evaluating the effects of different microplastics on different crops in extensive farming are limited. Therefore, we selected three major crops, Zea mays (ZM, monocotyledon), Glycine max (GM, dicotyledon, aboveground-bearing), and Arachis hypogaea (AH, dicotyledon, belowground-bearing) and investigated the effect of adding polyester microplastics (PES-MPs) and polypropylene microplastics (PP-MPs). Our results demonstrate that PP-MPs and PES-MPs decreased the soil bulk density of ZM, GM, and AH. Regarding soil pH, PES-MPs increased the soil pH of AH and ZM, whereas PP-MPs decreased the soil pH of ZM, GM, and AH compared to controls. Intriguingly, different coordinated trait responses to PP-MPs and PES-MPs were observed in all crops. In general, commonly measured parameters of AH, such as plant height, culm diameter, total biomass, root biomass, PSII maximum photochemical quantum yield (Fv/Fm), hundred-gain weight, and soluble sugar tended to decrease under PP-MPs exposure; however, some indicators of ZM and GM increased under PP-MPs exposure. PES-MPs had no obviously adverse influence on the three crops, except for the biomass of GM, and even significantly increased the chlorophyll content of AH, specific leaf area, and soluble sugar of GM. Compared with PES-MPs, PP-MPs have serious negative effects on crop growth and quality, especially AH. The findings of the present study provides evidence for evaluating the impact of soil microplastic pollution on crop yield and quality in farmland and lay a foundation for future investigations on the exploration of MP toxicity mechanisms and adaptability of different crops to microplastics.

Microplastic pollution in riverine ecosystems: threats posed on macroinvertebrates

Microplastics (MPs) are pollutants of emerging concern that have been reported in terrestrial and aquatic ecosystems as well as in food items. The increasing production and use of plastic materials have led to a rise in MP pollution in aquatic ecosystems. This review aimed at providing an overview of the abundance and distribution of MPs in riverine ecosystems and the potential effects posed on macroinvertebrates. Microplastics in riverine ecosystems are reported in all regions, with less research in Africa, South America, and Oceania. The abundance and distribution of MPs in riverine ecosystems are mainly affected by population density, economic activities, seasons, and hydraulic regimes. Ingestion of MPs has also been reported in riverine macroinvertebrates and has been incorporated in caddisflies cases. Further, bivalves and chironomids have been reported as potential indicators of MPs in aquatic ecosystems due to their ability to ingest MPs relative to environmental concentration. Fiber and fragments are the most common types reported. Meanwhile, polyethylene, polypropylene, polystyrene, polyethylene terephthalate (polyester), polyamide, and polyvinyl chloride are the most common polymers. These MPs are from materials/polymers commonly used for packaging, shopping/carrier bags, fabrics/textiles, and construction. Ingestion of MPs by macroinvertebrates can physically harm and inhibit growth, reproduction, feeding, and moulting, thus threatening their survival. In addition, MP ingestion can trigger enzymatic changes and cause oxidative stress in the organisms. There is a need to regulate the production and use of plastic materials, as well as disposal of the wastes to reduce MP pollution in riverine ecosystems.

Wind erosion induced low-density microplastics migration at landscape scale in a semi-arid region of northern China

Microplastics (MPs) have been extensively investigated in terrestrial environments, while the occurrence and movement of MPs at the landscape scale in semi-arid regions with serious wind erosion are less well studied. Here, we sampled film mulching farmland and downwind nearby grassland surface soils in a semi-arid region of northern China to explore the distribution of MPs at different downwind distances and the potential environmental risk to the local landscapes. The results revealed that the MP abundances presented a decreasing trend with increasing downwind distance (Mann-Kendall test, P < 0.01). The MP size distributions at different distances showed similar sigmoid trends described by logistic models. MP fiber size (500-2000 μm) abundance in the farmland was higher than that of the grassland. By contrast, MP non-fiber size (<1000 μm) abundance of farmlands was less than that of the grassland. The abundances of fibers larger than 500 μm and non-fibers larger than 1000 μm in size decreased exponentially with increasing downwind distance. The size of transported MPs at the landscape scale was larger than that of long-distance dispersal. The migration of MPs from farmlands can pose a potential threat to the downwind landscape, leading the downwind grassland to be a potential MP emission source. This study presents the first insights into the MPs distribution among different downwind distances at the landscape scale. Future research is required to deploy aeolian sediment sampling devices and establish the connection between the field data and the MP emission models.

Mechanism and characterization of microplastic aging process: A review

With the increasing production of petroleum-based plastics, the problem of environmental pollution caused by plastics has aroused widespread concern. Microplastics, which are formed by the fragmentation of macro plastics, are bio-accumulate easily due to their small size and slow degradation under natural conditions. The aging of plastics is an inevitable process for their degradation and enhancement of adsorption performance toward pollutants due to a series of changes in their physiochemical properties, which significantly increase the toxicity and harm of plastics. Therefore, studies should focus on the aging process of microplastics through reasonable characterization methods to promote the aging process and prevent white pollution. This review summarizes the latest progress in natural aging process and characterization methods to determine the natural aging mechanism of microplastics. In addition, recent advances in the artificial aging of microplastic pollutants are reviewed. The degradation status and by-products of biodegradable plastics in the natural environment and whether they can truly solve the plastic pollution problem have been discussed. Findings from the literature pointed out that the aging process of microplastics lacks professional and exclusive characterization methods, which include qualitative and quantitative analyses. To lessen the toxicity of microplastics in the environment, future research directions have been suggested based on existing problems in the current research. This review could provide a systematic reference for in-depth exploration of the aging mechanism and behavior of microplastics in natural and artificial systems.

Contamination and health risks of heavy metals in the soil of a historical landfill in northern China

Landfill-induced heavy metal (HM) contamination of soils is a widespread and complex problem. The levels and potential hazards of HM contamination in landfills must be evaluated before they can be reused for any purpose. In order to reuse a historical landfill in northern China, 376 sampling sites were selected in 2019 using the checkerboard layout method, and the levels of arsenic (As), mercury (Hg), antimony (Sb), copper (Cu), lead (Pb), cadmium (Cd), nickel (Ni), zinc (Zn), and thallium (Tl) in the soil were measured. Multiple evaluation methods established the HM pollution levels, agricultural suitability, and health risks associated with the sampling sites. In most parts of the study area, the concentrations of all nine HMs exceeded the screening levels and maximum allowable concentrations for agricultural soils. Only the soils in Zones 5 and 6 can be used for agricultural activity. Moreover, the deep soils were heavily contaminated with HMs in certain areas, possibly because of leaching and infiltration in the surface soil and the rise and diffusion of polluted groundwater. The soil HMs in the study area posed a higher carcinogenic risks to both adults and children. The average carcinogenic risk associated with As was 6.12 × 10^-4, which was the major contributor to carcinogenic risk at all HM-contaminated sites. The results of this work empirically demonstrated that soil HM pollution is severe and problematic in the study area and remedial measures are urgently required.

Environmental risks due to the presence of microplastics in coastal and marine environments of the Colombian Caribbean

Microplastics (MPs) are plastic sediments that are released into the environment by various sources, their abundance and distribution increase as their size decreases, they represent a risk to ecological processes and their abundance is related to their proximity to human activities and The Anthropocene era, in addition to the Covid-19 pandemic, has exacerbated the emitting sources of plastics such as face masks, disinfectant container bottles, among others, all due to all the biosafety measures required globally. Over time, the transformation of plastics into microplastics generates particles transported by atmospheric and water dynamics, being accumulated in soils, bodies of water and incorporated into ecosystems and the food chains of organisms, including humans. Marine-coastal environments such as coastal lagoons, which in addition to hosting strategic ecosystems, being areas of convergence of different ecological flows and with important ecosystem services, have also become sinks for MP particles, putting their productivity and value at risk. Socio-ecological that they have. The purpose of this research is to evaluate and zone the environmental risks derived from contamination by microplastics in a coastal lagoon system, since once the MPs enter the environment they can cause harmful effects, in this case in the Caribbean Sea and in the lagoon complex. To this end, a comprehensive study of planetary systems was carried out to better understand their disturbances due to the presence of microplastics.

Occurrence, distribution, and characteristics of microplastics in agricultural soil around a solid waste treatment center in southeast China

PURPOSE

In recent years, microplastic (MP) contamination has raised enormous concern. However, data on the influence of solid waste treatment systems on MP pollution around agricultural soil are lacking. This study investigated the distribution and characteristics of MPs in agricultural soil surrounding a solid waste treatment center in southeastern China.

MATERIALS AND METHODS

Fifty-seven agricultural topsoil samples around the solid waste treatment center were collected. The samples were pretreated by drying, flotation separation using NaCl solution, and digestion by H₂O₂. The abundance and morphological characteristics of MPs were determined by a microscope, followed by Raman spectroscopy analysis identified polymer types and SEM-EDS analysis observed surface morphology and the type of metals accumulated on the MPs.

RESULTS AND DISCUSSION

Soil MPs' abundance ranged from 280 to 2360 items/kg, while a higher abundance of MPs was distributed in the downwind area. The < 1-mm MPs were dominant, and white fragment MPs were widely found. Polyethylene (52.86%) and polypropylene (27.14%) were the most common. Moreover, SEM-EDS images illustrated that MPs were significantly weathered and showed the uneven distribution of metal(loid) elements on the surface, implying that MPs may migrate as heavy metal vectors to threaten agroecosystem safety.

CONCLUSIONS

This study reveals the distribution and characteristics of MPs in agricultural soil surrounding a solid waste treatment center in southeastern China, as well as the potential source of soil MPs, and provides systematic data for further research on MP pollution in agricultural soil.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s11368-022-03341-6.

Effect of microplastics on nasal and gut microbiota of high-exposure population: Protocol for an observational cross-sectional study

Microplastics have the characteristics of small size, high specific area, strong ability to adsorb pollutants, and difficult to degrade. They have become a major global environmental problem that humans urgently need to address. A balanced microecosystem is essential to human health. Animal studies have shown that long-term exposure to microplastics can change the characteristics of the microbiota in organisms, leading to respiratory, digestive, immune, and other system diseases. However, the current research on microplastics is still dominated by animal experiments, and the impact of microplastics on human health is still in its infancy, so relevant research is urgently needed. Twenty participants with high exposure to microplastics will come from a plastic factory in Chengdu, China. We will perform 16S rDNA sequencing on participants' nasal secretions, and stool samples. Additionally, we will perform 8700 LDIR laser infrared imaging of environmental soil and air filter membrane samples. For comparison, we will also collect samples from 20 volunteers from an area with good environmental quality in Chengdu. To find out the potential predictors and to access the difference between the groups, statistical analysis will be performed in the end. The study will be the first observational cross-sectional study focusing on the effects of microplastics on nasal and gut microbiota of high-exposure population. The study is expected to provide reliable evidence to fill the gaps in the impact of microplastics on human health.

Microplastic characteristic in the soil across the Tibetan Plateau

Microplastics are widely detected in terrestrial environments. However, microplastic features in the soil of remote areas are still sparse. In this study, microplastic pollution in soil across the Tibetan Plateau was systematically investigated. The results revealed that microplastic was ubiquitous in the soil of the Tibetan Plateau with an average abundance of 47.12 items/kg-dry weight (range: 5-340 items/kg). Compared with the published data of soil microplastic pollution in other regions, the microplastic pollution in the Tibetan Plateau was relatively low. Fibers represented 43.54% of microplastic particles detected, followed by fragments (32.20%) and films (23.78%). They mainly consisted of polyvinyl chloride, polyethylene, polypropylene, and polystyrene. Transparent and white microplastics were prevalent, and small microplastics (50-500 μm) occupied approximately 66% of all microplastics. High values of microplastics were found near Lhasa, Naqu, and Linzhi. Furthermore, microplastic pollution was found to be negatively related to the distance to the nearest city (p < 0.01), wind velocity (p = 0.014), altitude (p = 0.181), yet positively related to precipitation (p = 0.024). This work presents new insights into the magnitude of microplastics contamination in the soil across the Tibetan Plateau and supplies valuable data for future research on ecotoxicology, ecosystem impacts, and earth system feedback of microplastics on terrestrial ecosystems.

Occurrence of Microplastics from Plastic Fragments in Cultivated Soil of Sichuan Province: The Key Controls

With the continuous increase in the amount of mulch film, “white pollution” caused by plastic fragments (PF) has seriously affected agricultural production progress and poses a great threat to the safety and health of the agricultural environment. In the present study, PFs collected from 20 mulched agricultural farmlands in Sichuan Province were investigated. The PFs were separated and screened following the density flotation method. Optical microscopy was used to assess the fragments’ distribution, abundance, color, size, and morphology, and Raman spectroscopy was used to identify the types. In addition, through the analysis of a questionnaire survey, a random forest (RF) model was conducted to assess the effects of environmental factors on the amount of PF. The results showed that the abundance of PFs was the highest in Lade Town, Zigong City, reaching 1158.33 ± 52.04 particles kg−1. Meanwhile, PFs were less abundant in Foyin Town, Luzhou City, with 50.00 ± 25.00 particles kg−1; the morphology features of PF in the cultivated soil were mainly transparent (60.06%) and flaky-like (83.41%), with sizes < 5 mm (63.61%). In total, 75% of the representative PFs were PE PFs, while PVC PFs were 25%. The RF model indicated that there were significant effects due to the total mulch film amount, annual precipitation, and planting pattern on the number of derived residues (PF). This study provides data indicating the urgent need to prevent and control plastic pollution in mulch farming, specifically in the soils of Sichuan Province.

Hazardous contaminants in plastics contained in compost and agricultural soil

Macro-, meso- and microplastic (MAP, MEP, MP) occurrence in compost is an environmental issue whose extent and effects are not yet understood. Here, we studied the occurrence of MAPs, MEPs and MPs in compost samples, and the transfer of hazardous contaminants from plastics to compost and soil. MAPs/MEPs and MPs concentrations in compost were 6.5 g/kg and 6.6 ± 1.5 pieces/kg; from common recommendations for compost application, we estimated ∼4-23 × 10⁷ pieces MPs and 4-29 × 10⁴ g MAPs/MEPs ha^-1 per year ending into agricultural soils fertilized with such compost. Regarding contaminants, bis(ethylhexyl) phthalate, acetyl tributyl citrate, dodecane and nonanal were extracted in higher concentrations from plastics and plastic-contaminated compost than from compost where MAPs/MEPs had been removed prior to extraction and analysis. However, some contaminants were present even after MAPs/MEPs removal, ascribable to short- and long-term release by MAPs/MEPs, and to the presence of MPs. DEHP concentration was higher in soils where compost was applied than in fields where it was not used. These results, along with estimations of plastic load to soil from the use of compost, show that compost application is a source of plastic pollution into agricultural fields, and that plastic might transfer hazardous contaminants to soil.

Impact of microplastics on growth, photosynthesis and essential elements in Cucurbita pepo L

In this study, Cucurbita pepo L., one of the most cultivated, consumed and economically important crop worldwide, was used as model plant to test the toxic effects of the four most abundant microplastics identified in contaminated soils, i.e. polypropylene (PP), polyethylene (PE), polyvinylchloride (PVC), and polyethyleneterephthalate (PET). Cucurbita plants were grown in pots with increasing concentrations of the microplastics, then plant biometry, photosynthetic parameters and ionome of treated vs. untreated samples were compared to evaluate the toxicity of each plastic. All the pollutants impaired root and, especially, shoot growth. Specific and concentration-dependant effects of the different microplastics were found, including reduction in leaf size, chlorophyll content and photosynthetic efficiency, as well as changes in the micro- and macro-elemental profile. Among all the microplastics, PVC was identified as the most toxic and PE as the less toxic material. PVC decreased the dimensions of the leaf lamina, the values of the photosynthetic performance index and the plant iron concentration to a higher extent in respect to the other treatments. Microplastic toxicity exerted on the growth of C. pepo raises concerns about possible yield and economic loss, as well as for risks of a possible transfer into the food chain.

Recent advances on ecological effects of microplastics on soil environment

The mass production and wide application of plastics and their derivatives have led to the release of a large number of discarded plastic products into the natural environment, where they continue to accumulate due to their low recycling rate and long durability. These large pieces of plastic will gradually break into microplastics (<5 mm), which are highly persistent organic pollutants and attract worldwide attention due to their small particle size and potential threats to the ecosystem. Compared with the aquatic system, terrestrial systems such as soils, as sinks for microplastics, are more susceptible to plastic pollution. In this article, we comprehensively summarized the occurrence and sources of microplastics in terrestrial soil, and reviewed the eco-toxicological effects of microplastics in soil ecosystems, in terms of physical and chemical properties of soil, soil nutrient cycling, soil flora and fauna. The influence of microplastics on soil microbial community, and particularly the microbial community on the surface of microplastics, were examined in detail. The compound effects of microplastics and other pollutants, e.g., heavy metals and antibiotics, were addressed. Future challenges of research on microplastics include development of new techniques and standardization for the extraction and qualitative and quantitative analysis of microplastics in soils, toxic effects of microplastics at microbial or even molecular levels, the contribution of microplastics to antibiotic resistance genes migration, and unraveling microorganisms for the degradation of microplastics. This work provides as a better understanding of the occurrence, distribution and potential ecological risks of microplastics in terrestrial soil ecosystems.

Chemical Analysis of Microplastics and Nanoplastics: Challenges, Advanced Methods, and Perspectives

Microplastics and nanoplastics have become emerging particulate anthropogenic pollutants and rapidly turned into a field of growing scientific and public interest. These tiny plastic particles are found in the environment all around the globe as well as in drinking water and food, raising concerns about their impacts on the environment and human health. To adequately address these issues, reliable information on the ambient concentrations of microplastics and nanoplastics is needed. However, micro- and nanoplastic particles are extremely complex and diverse in terms of their size, shape, density, polymer type, surface properties, etc. While the particle concentrations in different media can vary by up to 10 orders of magnitude, analysis of such complex samples may resemble searching for a needle in a haystack. This highlights the critical importance of appropriate methods for the chemical identification, quantification, and characterization of microplastics and nanoplastics. The present article reviews advanced methods for the representative mass-based and particle-based analysis of microplastics, with a focus on the sensitivity and lower-size limit for detection. The advantages and limitations of the methods, and their complementarity for the comprehensive characterization of microplastics are discussed. A special attention is paid to the approaches for reliable analysis of nanoplastics. Finally, an outlook for establishing harmonized and standardized methods to analyze these challenging contaminants is presented, and perspectives within and beyond this research field are discussed.

Identification and removal of micro- and nano-plastics: Efficient and cost-effective methods

Microplastics (MPs) and nanoplastics (NPs) have gained much attention in recent years because of their ubiquitous presence, which is the widely acknowledged threat to the environment. MPs can be <5 mm size, while NPs are <100 nm, and both can be detected in various forms and shapes in the environment to alleviate their harmful effects on aquatic species, soil organisms, birds, and humans. In efforts to address these issues, the present review discusses about sampling methods for water, sediments, and biota along with their merits and demerits. Various identification techniques such as FTIR, Raman, ToF-SIMS, MALDI TOF MS, and ICP-MS are critically discussed. The detrimental effects caused by MPs and NPs are discussed critically along with the efficient and cost-effective treatment processes including membrane technologies in order to remove plastics particles from various sources to mitigate their environmental pollution and risk assessment.

Polyvinyl chloride in consumer and environmental plastics, with a particular focus on metal-based additives

Polyvinyl chloride (PVC) is one of the most widely used thermoplastics but is also a material of concern because of the generation and release of harmful chemicals during its life cycle. Amongst the chemicals added to PVC are metal-based stabilisers and Sb-based halogenated flame retardant synergists. However, very little quantitative information exists on these additives, and in particular in PVC lost to the environment. In this study, the distribution of PVC amongst consumer plastics in societal circulation and plastics retrieved from marine and lacustrine beaches and agricultural soils are compared, along with the presence and concentrations of Ba, Cd, Pb, Sb, Sn and Zn as proxies for common metal-based additives and determined by X-ray fluorescence spectrometry. About 10% of consumer plastics and 2% of environmental plastics were constructed of PVC, with the discrepancy attributed to the long service lives and managed disposal of PVC used in the construction sector and the propensity of the plastic to sink in aquatic systems and evade detection. Metal-based additives, defined as having a metal concentration >1000 mg kg^-1, were present in about 75% of consumer and environmental PVC, with Ba and Pb most abundant and Cd and Zn least abundant in both types of sample, and median concentrations statistically different only for Ba. Metals also appeared to be present as contaminants (defined as concentrations <1000 mg kg^-1) arising from manufacturing or recycling. Metals in PVC are believed to pose little risk when the material is in use, but experimental evidence in the literature suggests that significant mobilisation and exposure may occur from PVC microplastics when ingested by wildlife.

Microplastics in soil: A review on methods, occurrence, sources, and potential risk

Microplastic is an emerging contaminant of concern in soil globally due to its widespread and potential risks on the ecological system. Some basic issues such as the occurrence, source, and potential risks of microplastics in the soil are still open questions. These problems arise due to the lack of systematic and comprehensive analysis of microplastic in soils. Therefore, we comprehensively reviewed the current status of knowledge on microplastics in soil on detection, occurrence, characterization, source, and potential risk. Our review suggests that microplastics are ubiquitous in soil matrices globally. However, the research progress of microplastics in the soil is restricted by inherent technological inconsistencies and difficulties in analyzing particles in complex matrices, and studies on the occurrence and distribution of microplastics in soil environments remain very scarce, especially in Africa, South America, and Oceania. The consistency of the characteristics and composition of the microplastics in the aquatic environment and soil demonstrate they may share sources and exchange microplastics. Wide and varied sources of microplastic are constantly filling the soil, which causes the accumulation of microplastics in the soil. Studies on the effects and potential risks of microplastics in soil ecosystems are also reviewed. Limited research has shown that the combination and interaction of microplastics with contaminants they absorbed may affect soil health and function, and even migration along the food chain. The occurrence and impact of microplastic on the soil depend on the morphology, chemical components, and natural factors. We conclude that large research gaps exist in the quantification and estimation of regional emissions of microplastics in soil, factors affecting the concentration of microplastics, and microplastic disguising as soil carbon storage, which need more effort.

Solid waste: An overlooked source of microplastics to the environment

Microplastics pollution is one of the most pressing environmental problems of the 21st century. While microplastics are pervasive throughout various environmental compartments, research to date has primarily focused on marine systems. Land-based microplastics sources (e.g., solid waste) have received comparatively little attention, although they account for the main flow of microplastics into aquatic environments. Solid waste microplastics sources primarily include landfill refuse, sludge, and food waste. Microplastics in these waste streams can be associated with various micropollutants that can have deleterious impacts on ecosystem health as they enter the food chain. Thus, understanding the occurrence, fate, and degradation pathways of solid waste microplastics is essential to develop comprehensive control and mitigation strategies. This study critically reviewed these key aspects of microplastics in municipal solid waste landfill refuse, sewage sludge, and food waste, and identified the interconnections of these components in the proliferation of microplastics to the environment. Additionally, microplastics related laws and regulations and their relevance to solid waste microplastics mitigation are discussed.

Non-biodegradable microplastics in soils: A brief review and challenge

Non-biodegradable microplastics (MPs) pollution long-termly existed in soils, and was only concerned in recent years. In order to better understand MP behavior in soils, the sources, migration, distribution, biological effects, degradation and analytical methodology of non-biodegradable MPs in soils were quantificationally summarized from 170 publications based on Web of Science in 1950-2020. From the publications, we found these studies were mainly carried out in the Asia (60.0%) and Europe (23.3%), and most were on agricultural soils (68.5%). Polyethylene-MP (78.8% of the studies), Polypropylene-MP (78.8%), and Polystyrene-MP (45.5%) were the MPs most frequently found in the soils, with a MP size of 20-5000 µm being most common. Of the soil samples 64.3% contained MP 1000-4000 items kg^-1, and the colour frequency ranking is blue (66.7%) > white (61.1%) ≈ red ≈ black. MPs changed the soil microenvironment and microorganism activity, and caused the negative effects on both soil animals (100%) and plants (57.9%). MP degradation was influenced by the photooxidation reactions, microorganism activities, enzymatic effects, environmental conditions, and by the composition, size and morphology of the MPs. An optional analytical method was suggested in this study. At the end of paper, the urgent and important research work in the future was prospected.

Modeling the Conditional Fragmentation-Induced Microplastic Distribution

Microplastics (MPs) are drawing increasing attention from the international community due to their potential threats to the ecosystem and human health. Although their occurrence and spatial distribution have been extensively studied in recent years, the relationship between their abundance and sizes remains unclear. Moreover, the underlying mechanisms dominating their size distribution have rarely been explored. In the present study, we developed a novel conditional fragmentation model to describe MP size distribution in the soil environment. It is proposed that the distribution of MPs is not a coincidence but controlled by conditional aging. The applicability of this model was tested using data collected from different land use settings in Beijing, China. A distinct downsizing phenomenon from fibers, films, and fragments to granules is observed. Undisturbed land use types accumulated larger sized MPs with higher stability, while human interference accelerated the fragmentation of MPs. Both morphological analysis and time-of-flight secondary ion mass spectroscopy (TOF-SIMS) observations provided direct evidence for the conditional fragmentation process. Furthermore, the model has proven to be suitable for describing the size distribution of MPs from various sources (including atmospheric deposition, transportation, and agriculture) and aging processes (such as mechanical abrasion, chemical oxidation, and photochemical transformation). It is proposed that this model can be used for various purposes in MP-related studies, especially source identification, transport modeling, and risk assessment.

Optical Monitoring of Microplastics Filtrated from Wastewater Sludge and Suspended in Ethanol

The abundance of microplastics (MPs) in the atmosphere, on land, and especially in water bodies is well acknowledged. In this study, we establish an optical method based on three different techniques, namely, specular reflection to probe the medium, transmission spectroscopy measurements for the detection and identification, and a speckle pattern for monitoring the sedimentation of MPs filtrated from wastewater sludge and suspended in ethanol. We used first Raman measurements to estimate the presence and types of different MPs in wastewater sludge samples. We also used microscopy to identify the shapes of the main MPs. This allowed us to create a teaching set of samples to be characterized with our optical method. With the developed method, we clearly show that MPs from common plastics, such as polypropylene (PP), polyethylene terephthalate (PET), polystyrene (PS), and polyethylene (PE), are present in wastewater sludge and can be identified. Additionally, the results also indicate that the density of the plastics, which influences the sedimentation, is an essential parameter to consider in optical detection of microplastics in complex natural environments. All of the methods are in good agreement, thus validating the optics-based solution.

Towards the Development of Portable and In Situ Optical Devices for Detection of Micro and Nanoplastics in Water: A Review on the Current Status

The prevalent nature of micro and nanoplastics (MP/NPs) on environmental pollution and health-related issues has led to the development of various methods, usually based on Fourier-transform infrared (FTIR) and Raman spectroscopies, for their detection. Unfortunately, most of the developed techniques are laboratory-based with little focus on in situ detection of MPs. In this review, we aim to give an up-to-date report on the different optical measurement methods that have been exploited in the screening of MPs isolated from their natural environments, such as water. The progress and the potential of portable optical sensors for field studies of MPs are described, including remote sensing methods. We also propose other optical methods to be considered for the development of potential in situ integrated optical devices for continuous detection of MPs and NPs. Integrated optical solutions are especially necessary for the development of robust portable and in situ optical sensors for the quantitative detection and classification of water-based MPs.

A probabilistic risk assessment of microplastics in soil ecosystems

Plastics have a variety of applications due to their versatility, relative cost, and strength-to-weight ratio, and resistance to degradation. As a result, plastic waste can be found in all corners of the Earth. A class of plastic contaminants that have received increasing attention in terms of their potential impact on ecosystems is microplastics (≤5 mm). The greatest attention to date has been on their potential effect in marine ecosystems. However, a growing number of studies are examining their potential impact on soil ecosystems. The data reported in the literature on the environmentally-relevant concentrations of microplastics in soils and the concentration of microplastics that causes an adverse effect in soil biota were used to perform a probabilistic risk assessment of microplastics to soil biota. An environmental exposure distribution was constructed from the concentrations of microplastics reported in soil in the literature. Species sensitivity distributions were constructed using concentration of microplastics in soil that had no adverse effect on soil species (NOEC) or the lowest concentrations that had an adverse effect on soil species (LOEC) reported in the literature. The 95th centile of the environmental exposure distribution (8147 microplastic particles per gram of soil) was greater than 22 and 28% of the species sensitivity distribution constructed using NOECs and LOECs, respectively. The assessment concluded that environmentally relevant concentrations of microplastics reported in the literature could pose a considerable risk to soil biota. It is also important to note that due to the continued production of large quantities of plastic and the persistence of microplastics in the environment, environmentally-relevant concentrations of microplastics in soil are likely to only rise.

Marine Waste-Sources, Fate, Risks, Challenges and Research Needs

The article presents a comprehensive and cross-cutting review of key marine waste issues, taking into account: sources, fate, risks, transport pathways, threats, legislation, current challenges, and knowledge gaps. The growing amount of both human-created waste in seas and oceans and waste reaching marine ecosystems from land is one of today's challenges for the global economy and the European Union. It is predicted that if no decisive steps are taken to limit the amount of this type of waste, there may be more plastic waste than fish in the oceans after 2050. The influence of microplastics and nanoplastics on living organisms remains undiagnosed. Within the international and EU law, solutions are being developed to properly manage waste on board ships and to reduce the impact of processes related to the recycling of the vessels on the environment. Currently, over 80% of ships are dismantled in the countries of South Asia, in conditions that threaten the environment and the safety of workers. After World War 2, large quantities of chemical weapons were deposited in the seas. Steel containers with dangerous substances residing in the sea for over 70 years have begun leaking, thus polluting water. For many years, radioactive waste had also been dumped into marine ecosystems, although since 1993 there has been a total ban on such disposal of radionuclides. The impact of the COVID-19 pandemic on marine waste generation has also been presented as a significant factor influencing marine waste generation and management.

Zirconia-Alumina Composites Obtained by Centrifugal Slip Casting as Attractive Sustainable Material for Application in Construction

This paper focuses on the possibility of adapting the centrifugal slip casting method to obtain zirconia-alumina composite materials in the form of finished tube-shaped products. These types of products, due to their unique properties, can be utilised, for example, in the transport of aggressive substances, even in extreme temperatures or corrosive conditions. The study reports on the two series of zirconia-alumina composites differing in the content of ZrO₂-2.5 and 25 vol%. The fabricated and sintered materials were characterised using scanning electron microscopy (SEM), X-ray diffraction (XRD) and stereological analysis. Moreover, a life cycle assessment (LCA) was provided in accordance with the requirements of the ISO 14044 and EN 15805 standards. The obtained data clearly show that the centrifugal slip casting method allows obtaining samples with high density and extremely uniform distribution of the ZrO₂ phase in the alumina matrix. The stereological analysis results proved also that the addition of ZrO₂ is effective in reducing the growth of Al₂O₃ grains during the sintering process. The phase analysis carried out by means of XRD showed that during the sintering process, in the case of composites with a lower ZrO₂ content (2.5 vol%), the monoclinic to tetragonal transformation of ZrO₂ was total, while for samples containing 25 vol% ZrO₂, the monoclinic phase remained in a small amount in the final product.

Abundance and distribution characteristics of microplastic in plateau cultivated land of Yunnan Province, China

Microplastic pollution in cultivated soil has received increasing attention recently. There may be more serious microplastic abundance but little research has been done in cultivated soil in plateau areas. To survey the pollution characteristics of microplastics in inland cultivated soil, 100 soil samples collected from 10 counties of Yunnan Province were investigated through density separation and microscopic examination. The research results showed that microplastic abundance was in the range of 0.9 × 10³ to 40.8 × 10³ particles (kg Ds)^-1 with average abundance of 9.8 × 10³ particles (kg Ds)^-1. Moreover, compared with other studies on sediments, it was found that microplastic abundance in inland soil was one order of magnitude higher than that in offshore sediments. The use of plastic mulch and its long-term residue in cultivated soil was an important reason for microplastic pollution. In this survey, various morphologies of microplastics existed, including fragment (78.3%), transparent/translucency (49.7%), and micro-size microplastics (< 500 μm) (89.3%). And the microplastic morphologies occurred in different degrees of aging phenomenon under the influence of the environment factors such as ultraviolet radiation. The findings provided the pollution status of microplastics in cultivated soil, and more attention should be paid to inland soil microplastic pollution. Grapical abstract.

Microplastics in soils: A review of methods, occurrence, fate, transport, ecological and environmental risks

The global prevalence of microplastics (MPs) poses a potential threat and unpredictable risk to the function and health of environmental systems. However, the research progress of soil MPs is restricted by the inherent technical inconformity and difficulties in analyzing particles in complex matrices. Here, we reviewed a selection of papers and then extrapolated a tentative standardized method for such analyses. The multiple sources of soil MPs in soil need to be quantified. Global monitoring data of soil MPs is far from sufficient. The interaction between MPs and different properties and environmental factors controls the migration and retention of MPs in soil. The migration behavior and key mechanisms of MPs in real-world environments remain to be determined. The presence of MPs threatens soil microbial-plant-animal ecosystem function and health, and may enter the human body through the food chain, although the extent of these hazards is currently debated. In particular, attention should be paid to the potential transport and ecotoxicological mechanisms of contaminants derived and adsorptive from MPs and of harmful microorganisms (such as pathogens) attached as biofilms. Although there exist preliminary studies on soil MPs, it is urgent to consider the diversity of MPs as a suite of contaminants and to systematically understand the sources, flux and effects of these artificial pollutants in time and space from the perspective of plastic environmental cycle. More comprehensive quantification of their environmental fate is undertaken to identify risks to global human and ecological systems. From the perspective of controlling soil MP pollution, the responsibility assignment of government manage-producer-consumer system and the strategy of remediation should be implemented. This review is helpful for providing an important roadmap and inspiration for the research methods and framework of soil MPs and facilitates the development of waste management and remediation strategies for regional soil MP contamination.

Olive oil-based method for the extraction, quantification and identification of microplastics in soil and compost samples

Microplastics (MPs) have become a pressing environmental concern over the past few years and their extraction from solid samples is a scientific challenge that needs to be faced and solved. Standardized and validated protocols for MPs extraction are lacking and the existing methodology, such as density separation, is often unable to separate high density polymers. The aim of our research was to develop a non-density based, inexpensive, simple and safe method to extract MPs from soil and compost samples. We tested an oil-based extracting technique exploiting the oleophilic properties of plastics. For validating the method, soil and compost samples were spiked with six different micro-polymers: polyethylene, polystyrene, polyvinyl chloride, polycarbonate, polyethylene terephthalate and polyurethane. The obtained results are promising, and the polymer density had only a small role in the recovery rate: low, medium and high density polymers reached a mean recovery rate of 90% ±2%, 97% ± 5% and 95% ± 4%, respectively.