Microplastics pollution in the terrestrial environments: Poorly known diffuse sources and implications for plants

Quantification and polymeric characterization of microplastics in composts and their accumulation in lettuce

Organic fertilizers have become a vector for the transport of microplastics (MPs), which pose human health concerns through the food chain. This study aimed to quantify and characterize MPs in eight different compost samples of various raw materials and their subsequent translocation to lettuce (Lacuta sativa) grown on contaminated composts. The results revealed that the MP abundance ranged from 3810 to 16530 MP/kg. Municipal solid waste compost (MSWC) had highest abundance (16082 ± 632 MP/kg), followed by leaf compost (LC) and organic compost (OC) (6299 ± 1011 and 3680 ± 419 MP/kg, respectively). MPs of <100 μm in size were most dominant in MSWC and LC. Fragments and fibers were the prevalent shape types, with white/transparent colored MPs being more abundant. Polyethylene (PE), polypropylene (PP) and polyethylene terephthalate (PET) were the dominant polymers. MPs accumulation in the lettuce leaves was greatest in the lettuce plants grown on MSWC, followed by those grown on LC and OC, indicating that MSWC grown lettuce is not suitable for human consumption. The decrease in the growth (leaf length, number of leaves, leaf fresh and weights) and physiological (membrane stability index, relative water contents) parameters of lettuce was in line with the trend of MP accumulations. Hence, it is highly important to regulate the plastic contents in compost because it is a threat to ecosystems and human health.

Unveiling the hidden impact: How biodegradable microplastics influence CO2 and CH4 emissions and Volatile Organic Compounds (VOCs) profiles in soil ecosystems

Biodegradable plastics promise eco-friendliness, yet their transformation into microplastics (bio-MPs) raises environmental alarms. However, how those bio-MPs affect the greenhouse gases (GHGs) and volatile organic compounds (VOCs) in soil ecosystems remains largely unexplored. Here, we investigated the effects of diverse bio-MPs (PBAT, PBS, and PLA) on GHGs and VOCs emission in typical paddy or upland soils. We monitored the carbon dioxide (CO2) and methane (CH4) fluxes in-situ using the self-developed portable optical gas sensor and analyzed VOC profiles using a proton-transfer reaction mass spectrometer (PTR-MS). Our study has revealed that, despite their biodegradable nature, bio-MPs do not always promote soil GHG emissions as previously thought. Specifically, PBAT and PLA significantly increased CO2 and CH4 emissions up to 1.9-7.5 and 115.9-178.5 fold, respectively, compared to the control group. While PBS exhibited the opposite trend, causing a decrease of up to 39.9% for CO2 and up to 39.9% for CH4. In addition, different types of bio-MPs triggered distinct soil VOC emission patterns. According to the Mann-Whitney U-test and Partial Least Squares Discriminant Analysis (PLS-DA), a recognizable VOC pattern associated with different bio-MPs was revealed. This study claims the necessity of considering polymer-specific responses when assessing the environmental impact of Bio-MPs, and providing insights into their implications for climate change.

Challenges and Recent Analytical Advances in Micro/Nanoplastic Detection

Despite growing ecological concerns, studies on microplastics and nanoplastics are still in their initial stages owing to technical hurdles in analytical techniques, especially for nanoplastics. We provide an overview of the general attributes of micro/nanoplastics in natural environments and analytical techniques commonly used for their analysis. After demonstrating the analytical challenges associated with the identification of nanoplastics due to their distinctive characteristics, we discuss recent technological advancements for detecting nanoplastics.

Comparison of microplastic type, size, and composition in atmospheric and foliage samples in an urban scenario

The rising trend of plastic production in last years and the inadequate disposal of related waste has raised concerns regarding microplastic-related environmental issues. Microplastic particles disperse by means of transport and deposition processes to different ecosystems and enter food chains. In this paper, atmospheric deposition and foliage samples of two species (i.e., Hedera helix and Photinia glabra) were collected and analysed for the quantity and identity of microplastics (MPs). A preliminary methodology to treat foliage samples and subsequently identify MPs using a quantum cascade laser IR spectrophotometer is presented. The treatment of airborne samples involved filtration, mild digestion, concentration, and transfer onto reflective slides whereas that for foliage involved washing, concentration, and transference of putative MPs onto reflective slides. Fibers and fragments were differentiated according to their physical features (size, width, height, etc.) and calculating derived characteristics (namely, circularity and solidity). The preliminary results obtained suggest a good agreement between atmospheric-deposited and foliage-retained MPs, showing the capability of leaves to act as passive samplers for environmental monitoring.

Physiological and biochemical effects of polystyrene micro/nano plastics on Arabidopsis thaliana

Microplastics have garnered global attention due to their potential ecological risks. Research shows micro/nano-plastics pollution has adverse effects on plant growth, development, and physiological characteristics. However, the mechanisms underlying these effects remain unclear. The study examined the effects of polystyrene micro/nano-plastics with varying sizes and concentrations on different physiological and biochemical markers of A. thaliana. The indicators assessed include seed viability, growth, chlorophyll content, accumulation of root reactive oxygen species, and root exudates. Using fluorescence labeling, we investigated the absorption and translocation processes of micro/nano-plastics in A. thaliana. We also performed transcriptomic analysis to better understand the particular mechanisms of micro/nano-plastics. It indicated that micro/nano-plastics had an adverse effect on seed germination, especially under high concentration and small particle size treatments. This effect diminished with prolonged exposure. High concentrations at 50 nm and 100 nm treatment groups significantly inhibited the growth. Conversely, low concentrations of 1000 nm had a promoting effect. Exposure to micro/nano-plastics potentially resulted in decreased chlorophyll content, the accumulation of H2O2 in roots, and stimulated root secretion of oxalic acid. Through transcriptomic analysis, the gene expression linked to micro/nano-plastic treatments of varying sizes enriched multiple metabolic pathways, impacting plant growth, development, environmental adaptation, metabolism, pigment synthesis, and stress response.

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

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

Sustainable use of plastic-derived nanocarbons as a promising larvicidal and growth inhibitor agent towards control of mosquitoes

Nanoscale carbon was obtained from six widely used plastics (PET, HDPE, PVC, LDPE, PP and PP) via thermal degradation (600 °C) under inert atmosphere. The thermally degraded products were processed through bath sonication followed by lyophilisation and the same was characterized through proximate analysis, UV-Vis spectroscopy, Scanning electron micrograph (SEM) with energy dispersive X-ray (EDX) analysis, Transmission electron micrograph (TEM), Dynamic light scattering (DLS) and Fourier transform infrared spectroscopy (FTIR). A series of aqueous solution of nanoscale carbon (5-30 mg/L) were prepared and same were used as both mosquito growth inhibitor and larvicidal agent against 3rd and 4th instar larvae of Culex pipiens. The significant percent mortality results were recorded for LDPE (p < 0.007) with average particle size of 3.01 nm and 62.95 W% of carbon and PS (p < 0.002) with average particle size of 12.80 nm and 58.73 W% of carbon against 3rd instar larvae, respectively. Similarly, for 4th instar larvae, both significant pupicidal and adulticidal activity were also recorded for PET (F = 24.0, p < 0.0001 and F = 5.73, p < 0.006), and HDPE (F = 26.0, p < 0.0001) and F = 5.30, p < 0.008). However, significant pupicidal activity were observed for PVC (F = 6.90, p < 0.003), and PS (F = 21.30, p < 0.0001). Histological, bio-chemical and microscopic studies were revealed that nanoscale carbon causes mild to severe damage of external and internal cellular integrity of larvae. However, nanoscale carbon does not exhibit any chromosomal abnormality and anatomical irregularities in Allium cepa and Cicer arietinum, respectively. Similarly, non-significant results with respect to blood cell deformation were also recorded from blood smear of Poecilia reticulata. Therefore, it can be concluded that plastic origin nanoscale carbon could be a viable sustainable nano-weapon towards control of insects.

Short-term impacts of polyethylene and polyacrylonitrile microplastics on soil physicochemical properties and microbial activity of a marine terrace environment in maritime Antarctica

Evidence of microplastic (MP) pollution in Antarctic terrestrial environments reinforces concerns about its potential impacts on soil, which plays a major role in ecological processes at ice-free areas. We investigated the effects of two common MP types on soil physicochemical properties and microbial responses of a marine terrace from Fildes Peninsula (King George Island, Antarctica). Soils were treated with polyethylene (PE) fragments and polyacrylonitrile (PAN) fibers at environmentally relevant doses (from 0.001% to 1% w w-1), in addition to a control treatment (0% w w-1), for 22 days in a pot incubation experiment under natural field conditions. The short-term impacts of MPs on soil physical, chemical and microbial attributes seem interrelated and were affected by both MP dose and type. The highest PAN fiber dose (0.1%) increased macro and total porosity, but decreased soil bulk density compared to control, whereas PE fragments treatments did not affect soil porosity. Soil respiration increased with increasing doses of PAN fibers reflecting impacts on physical properties. Both types of MPs increased microbial activity (fluorescein diacetate hydrolysis), decreased the cation exchange capacity but, especially PE fragments, increased Na+ saturation. The highest dose of PAN fibers and PE fragments increased total nitrogen and total organic carbon, respectively, and both decreased the soil pH. We discussed potential causes for our findings in this initial assessment and addressed the need for further research considering the complexity of environmental factors to better understand the cumulative impacts of MP pollution in Antarctic soil environments.

White Stork Pellets: Non-Invasive Solution to Monitor Anthropogenic Particle Pollution

The present study applied a non-invasive method to analyse anthropogenic particles and prey items in white stork (Ciconia ciconia) pellets. Pellets (n = 20) were obtained from white stork nests during the 2020 breeding season from two sites in Croatia. In total, 7869 anthropogenic particles were isolated. The majority of particles were fragments, while previous studies on other birds often reported fibres. An ATR-FTIR polymer analysis detected glass and construction and building materials, as well as several compounds associated with plastic masses. Polymer investigation revealed the presence of dotriacontane and octacosane, which are by-products of polyethylene (PE) degradation and transformation. Additionally, the detection of vinylidene chloride (VDC) highlights the historical contribution of polyvinylidene chloride (PVDC) to plastic pollution. Significant variation in particle quantity and size between the sampling sites was detected, with larger particles found at sites associated with the metal mechanical engineering industry and agriculture. Prey assessment revealed chitin remains of large insects such as Orthoptera and Coleoptera. This research confirms the potential of pellet analysis as a valuable tool for assessing the presence of anthropogenic particles in the environment. However, further research is needed to fully understand the extent of particle ingestion, particle sources and potential impact.

Soils in distress: The impacts and ecological risks of (micro)plastic pollution in the terrestrial environment

Plastics have revolutionised human industries, thanks to their versatility and durability. However, their extensive use, coupled with inadequate waste disposal, has resulted in plastic becoming ubiquitous in every environmental compartment, posing potential risks to the economy, human health and the environment. Additionally, under natural conditions, plastic waste breaks down into microplastics (MPs<5 mm). The increasing quantity of MPs exerts a significant burden on the soil environment, particularly in agroecosystems, presenting a new stressor for soil-dwelling organisms. In this review, we delve into the effects of MP pollution on soil ecosystems, with a specific attention to (a) MP transport to soils, (b) potential changes of MPs under environmental conditions, (c) and their interaction with the physical, chemical and biological components of the soil. We aim to shed light on the alterations in the distribution, activity, physiology and growth of soil flora, fauna and microorganisms in response to MPs, offering an ecotoxicological perspective for environmental risk assessment of plastics. The effects of MPs are strongly influenced by their intrinsic traits, including polymer type, shape, size and abundance. By exploring the multifaceted interactions between MPs and the soil environment, we provide critical insights into the consequences of plastic contamination. Despite the growing body of research, there remain substantial knowledge gaps regarding the long-term impact of MPs on the soil. Our work underscores the importance of continued research efforts and the adoption of standardised approaches to address plastic pollution and ensure a sustainable future for our planet.

Biodegradation of microplastics: Advancement in the strategic approaches towards prevention of its accumulation and harmful effects

Microplastics (MPs) are plastic particles in a size ranging from 1 mm to 5 mm in diameter, and are formed by the breakdown of plastics from different sources. They are emerging environmental pollutants, and pose a great threat to living organisms. Improper disposal, inadequate recycling, and excessive use of plastic led to the accumulation of MP in the environment. The degradation of MP can be done either biotically or abiotically. In view of that, this article discusses the molecular mechanisms that involve bacteria, fungi, and enzymes to degrade the MP polymers as the primary objective. As per as abiotic degradation is concerned, two different modes of MP degradation were discussed in order to justify the effectiveness of biotic degradation. Finally, this review is concluded with the challenges and future perspectives of MP biodegradation based on the existing research gaps. The main objective of this article is to provide the readers with clear insight, and ideas about the recent advancements in MP biodegradation.

Characterization and source apportionment of microplastics in Indian composts

Microplastics (MP), small plastic particles under 5 mm, are pollutants known to carry heavy metals in ecosystems. Composts are a significant source of soil microplastics. This study examined MSW composts from Kochi and Kozhikode in India for microplastic concentrations and heavy metals' accumulation thereon. Microplastics were isolated using zinc chloride density separation, with Fenton's reagent used for organic matter oxidation. Resin types were identified using FTIR analysis that showed the presence of PE, PP, PS, nylon, PET, and allyl alcohol copolymer. In Kozhikode's compost, the average concentration of microplastics was 840 ± 30 items/kg, while Kochi had 1600 ± 111 items/kg, mainly polyethylene films. PE was the most prevalent resin, comprising 58.3% in Kozhikode and 73.37% in Kochi. Heavy metal analysis of MP showed significant concentrations of lead, cadmium, zinc, copper, and manganese adsorbed on the surface of microplastics. The concentrations of heavy metals in the MP before Fenton oxidation ranged from 1.02 to 2.02 times the corresponding concentrations in compost for Kozhikode and 1.23 to 2.85 times for Kochi. Source apportionment studies revealed that 64% of microplastics in Kozhikode and 77% in Kochi originated from single-use plastics. Ecological risk indices, PLI and PHI, showed that composts from both locations fall under hazard level V. The study revealed that compost from unsegregated MSW can act as a significant source of microplastics and heavy metals in the soil environment, with single-use plastics contributing major share of the issue.

Uptake, transport and accumulation of micro- and nano-plastics in terrestrial plants and health risk associated with their transfer to food chain - A mini review

Waste plastics enter the environment (water, soil, and atmosphere) and degrade into micro- and nano-plastics (MNPs) through physical, chemical, or biological processes. MNPs are ubiquitous in the environment and inevitably interact with terrestrial plants. Terrestrial plants have become important potential sinks, and subsequently, the sources of MNPs. At present, many studies have reported the effects of MNPs on plant physiology, biochemistry, and their phototoxicity. However, the source, detection method, and the absorption process of MNPs in terrestrial plants have not been systematically studied. In order to better understand the continuous process of MNPs entering terrestrial plants, this review introduces the sources and analysis methods of MNPs in terrestrial plants. The uptake pathways of MNPs in terrestrial plants and their influencing factors were systematically summarized. Meanwhile, the transport pathways and the accumulation of MNPs in different plant organs (roots, stems, leaves, calyxes, and fruits) were explored. Finally, the transfer of MNPs through food chains to humans and their health risks were discussed. The aim of this work is to provide significant theoretical knowledge to understand the uptake, transport, and accumulation of MNPs in terrestrial plants and the potential health risks associated with their transfer to humans through food chain.

Spatial distribution, source apportionment and potential ecological risk assessment of suspended atmosphere microplastics in different underlying surfaces in Harbin

Although suspended atmospheric microplastics (SAMPs) have been found to be ubiquitous and have potential impacts on human health, whereas studies related to source apportionment and potential ecological risk assessment in the atmospheric environment are still limited. This study investigated spatial distribution, source apportionment and potential ecological risk of SAMPs in six underlying surfaces of Harbin, China. The results show that all six underlying surfaces existed SAMPs, including polypropylene (PP), polyethylene terephthalate (PET) polyethylene (PE), polystyrene (PS) and polyvinyl chloride (PVC), with approximate 26.13 %, 24.10 %, 23.87 %, 13.51 %, and 12.39 %, respectively. SAMPs abundances from filtered air were relatively high and averaged 1.76 n/m3. The SAMPs mainly contained fibrous (59.01 %), fragmented (30.18 %), and granular (10.81 %) with transparent (62.39 %), black 13.74 %), red (7.43 %), white (6.53 %), blue, and yellow (3.60 %), and particle size ranged from 1.3 to 518 μm. In addition, source apportionment of SAMPs shows that SAMPs were originated from five emission sources including living source (19.53 %), construction source (12.08 %), transportation source (47.25 %), industrial source (5.11 %), and agricultural source (16.13 %) in Harbin. A significant correction was observed between SAMPs abundances and human activity (R = 0.68, P = 0.66), atmospheric humidity (R = -0.40, P = 0.02), and wind direction (R = 0.22, P = 0.04) in different underlying surface. Furthermore, potential ecological hazardous single index (EI) of PVC and PS were higher than PP, PET, and PS in the construction land, cultivated land, forest land, grassland, water area, and unused land. An estimation of the potential ecological risk index (RI) from SAMPs using Positive Matrix Factorization (PMF) model indicated that Harbin presented a minor ecological risk with average 16.59 of RI index of microplastics in environments. In conclusion, data in this study indicate that SAMPs are existed in atmospheric environments, which have possible risks for human health via inhalation.

Microplastics pollution in rice fields: a case study of Pir Bazar rural district of Gilan, Iran

Various stressors threaten rice fields' productivity. Microplastics (MPs) are ubiquitous pollutants that accumulate in agricultural soils, effectively impairing agroecosystem functioning. The study investigates the MPs pollution status of rice fields and compares it with that of non-paddy vegetable farms under contrasting management practices. Possible sources of MPs in the fields are identified. Additionally, the relationships between MPs abundance and soil characteristics are investigated. This provides innovative insights into the possible impact of MPs on soil health and functioning. Density separation using saturated NaCl solution and oxidative organic matter digestion using Fenton's reagent were employed to extract the MPs. The extracted MPs were categorized according to shape, size, and color. The results indicated that the paddies (1952.86±114.36 particles/kg) contained significantly more MPs than did the non-paddies (1134.44±221.52 particles/kg). Beads (53.75%) and fibers (28.46%) were the most common MPs. More than 90% of all MPs recovered from the fields were less than 1 mm in size. Of the 16 color groups identified, the colors silver, white, and black were the most abundant. Sewage sludge application and mulching were recognized as the primary sources of MPs in the paddies, with sludge contributing more than mulching. Microplastics were shown to potentially alter vital soil characteristics. Rice fields are otherwise overlooked reservoirs of MPs. More attention should be paid to raising awareness of their role as MPs accumulation hotspots among governmental bodies, researchers, producers, and citizens. Contributing MPs sources need to be identified, and managerial decisions should consider the polluting capacity of different practices.

Unveiling the effect of microplastics on agricultural crops - a review

Microplastics (MPs), ever since they were identified as a potential and widely distributed persistent contaminant, the number of studies highlighting their impacts on various terrestrial ecosystems have been increasing. Recently, the effect of MPs on the agricultural ecosystem has gained momentum. Hence, the present review examines the impact of microplastics on agricultural crop systems and the mechanism underlying its toxicity. The current review revealed that most of the studies were conducted at a laboratory scale and under controlled conditions. Additionally, it was observed that polystyrene (PS) followed by polyethylene (PE) are the most studied polymer type, while the most studied plants are wheat and maize. Hitherto, literature studies suggest that the microplastics' influence on plant growth can be negative or sometimes neutral; while in some cases it exerts a hormetic effect which depends on other factors determining plant growth. Notably, the main mechanisms through which microplastics influence plant growth are mechanical damage, alteration of soil properties, or by leaching of additives. Overall, with burgeoning research interest in this aspect, the current review has significant implications for the toxicity of MPs on plants and throws light on the need to develop novel guidelines toward the sustainable use of plastics in agricultural sector. However, realistic field-level studies and estimating the MPs concentration at various region are essential to develop remediation approaches. Future studies should also focus on translocation and accumulation of micron sized MPs in edible portion of crops and their effect on food safety.

Microplastics and their environmental effects

Microplastics (MPs) are acknowledged as emerging contaminants that pose a substantial threat to the environment. The adverse impacts of MP pollution extend across marine, freshwater, and terrestrial ecosystems, covering regions from the Tropics to the Poles. Although our comprehension of MP behavior has progressed in recent years, it is still difficult to predict exposure hotspots or exposure scenarios. Despite a noteworthy increase in data concerning MP occurrence in different environmental compartments and species, there is a noticeable scarcity of experimental data on MP uptake, accumulation, and effects. This Virtual Special Issue (VSI) received a total of 19 contributions from 11 countries, with a significant majority originating from Italy, India, Spain, and China. These contributions were categorized into three main themes: the occurrence and effects of MPs on aquatic and terrestrial organisms, the presence of chemical additives in plastics, and review articles summarizing previously published research on MPs.

Quantification and characterization of microplastics (MPs) pollution in peri-uburban agricultural lands of Lahore, Pakistan

Microplastics (MPs) contaminate every conceivable terrestrial and aquatic environment including high peaks and deep marine trenches. Agricultural lands alone are expected to receive plastic up to 23 times more than ocean basins. In this study, soil samples were collected from peri-urban agricultural lands of Lahore on four sides including Kala Shah Kaku (KSK), Punjab University (PU), Dera Gujran (DG), and Sagian (SG). National Oceanic and Atmospheric Administration (NOAA) protocol was used for MPs extraction and analysis. Extracted MPs were analyzed under microscope at 40X magnification and their composition was analyzed using Fourier Transform Infrared (FTIR) spectroscopy. A considerable concentration of MPs was recorded at all sites. The highest contamination was found at SG with 876 ±194 MPs/kg of soil, and the lowest contamination was recorded at PU with 672 ±235 MPs/kg of soil. However, these differences among the sites were not statistically significant (p = 0.29). The overall predominant shape of MPs was fibers (613±71, 79.73%) followed by sheets (125±55, 16.28%), fragments (30±5, 3.9%) and foam particles (1±2, .09%). The differences in the distribution of MPs in various types were statistically significant (p = 0), while differences between sites were insignificant (p = 0.13). About 95% of MPs were less than 2 mm and 85% were less than 1 mm size. The distribution of MPs in various sizes (p = 0) and differences of this distribution between sites (p = 0.037) were both statistically significant. A good diversity of nine colored MPs was recorded, however majority of the MPs were transparent (89.57%). Six polymer including Polyethylene (PE), Polyethylene terephthalate (PET), Polypropylene (PP), Polystyrene (PS), Polycarbonate (PC), and Polyvinyl Chloride (PVC) were identified by FTIR. The current levels of MPs pollution are higher than in many other parts of the world. Composition of MPs (types, colors, sizes, and polymer types) indicates the diversity of their sources and their possible implications on agricultural ecosystem.

Microplastic stress in plants: effects on plant growth and their remediations

Microplastic (MP) pollution is becoming a global problem due to the resilience, long-term persistence, and robustness of MPs in different ecosystems. In terrestrial ecosystems, plants are exposed to MP stress, thereby affecting overall plant growth and development. This review article has critically analyzed the effects of MP stress in plants. We found that MP stress-induced reduction in plant physical growth is accompanied by two complementary effects: (i) blockage of pores in seed coat or roots to alter water and nutrient uptake, and (ii) induction of drought due to increased soil cracking effects of MPs. Nonetheless, the reduction in physiological growth under MP stress is accompanied by four complementary effects: (i) excessive production of ROS, (ii) alteration in leaf and root ionome, (iii) impaired hormonal regulation, and (iv) decline in chlorophyll and photosynthesis. Considering that, we suggested that targeting the redox regulatory mechanisms could be beneficial in improving tolerance to MPs in plants; however, antioxidant activities are highly dependent on plant species, plant tissue, MP type, and MP dose. MP stress also indirectly reduces plant growth by altering soil productivity. However, MP-induced negative effects vary due to the presence of different surface functional groups and particle sizes. In the end, we suggested the utilization of agronomic approaches, including the application of growth regulators, biochar, and replacing plastic mulch with crop residues, crop diversification, and biological degradation, to ameliorate the effects of MP stress in plants. The efficiency of these methods is also MP-type-specific and dose-dependent.

Occurrence of Microplastics in Most Consumed Fruits and Vegetables from Turkey and Public Risk Assessment for Consumers

Microplastics are transferred to humans through the food chain by consuming food contaminated with microplastics. However, the knowledge about the risks of dietary exposure for humans to these particles is very limited. Moreover, only a few studies on microplastic pollution in fruit and vegetables have been carried on. Thus, this study aims to investigate the presence of microplastics in some of the most consumed fruits and vegetables (pear (Pyrus communis), apple (Malus domestica), tomato (Solanum lycopersicum), onion (Allium cepa), potatoes (Solanum tuberosum), and cucumber (Cucumis sativus)) from Turkey and to evaluate the potential risk for consumers. Fruits and vegetable samples were purchased from different markets and fruiterer (two of each) in Muğla province, Southwest of Turkey. Microplastic extraction processes were carried out on the edible parts of the samples. According to the results obtained, a total of 210 particles (2.9 ± 1.6 particle g-1) were detected in all samples. Any significant difference occurred among the different markets. The maximum average amount of microplastic was determined in tomato samples (3.63 ± 1.39 particle g-1). The highest microplastic intake was with tomato (398,520 particles individual-1 year-1 for Estimated Annual Intake (EAI) and Estimated Daily Intake (EDI) for children 68.24 particles kg-1 day-1). The occurrence of microplastics of big size, that are not allowed to pass by plant xylem transport, suggests that fresh vegetables and fruits can be contaminated with plastic, especially during the production phase, during agricultural activities and during the marketing process (transport to the market and purchasing process).

Microplastics: a review of their impacts on different life forms and their removal methods

The pollution of microplastics (MPs) is a worldwide major concern, as they have become a major part of our food chain. MPs enter our ecosystem via different pathways, including anthropogenic activities and improper disposal of plastics. The aim of this article is to review the current scientific literature related to MPs and how they affect different life forms on earth. Briefly, MPs induced negative effects on humans are primarily linked with the oxidative stress and disruption in immunity. MPs not only affect the soil chemical and physical properties such as reduction in soil health and productivity but also impose harmful effects on soil microorganisms. Moreover, MP-induced plant growth reduction results from three complementary mechanisms: (i) reduction in root and shoot growth, (ii) reduction in photosynthesis accompanied by higher reactive oxygen species (ROS) production, and (iii) reduction in nutrient uptake via altered root growth. Given the negative effects of MPs on different life forms, it is important to remove or remediate them. We have discussed different MP removal methods including coagulation, membrane filtration technology, biochar, and biological degradation of MPs in soil and wastewater effluents. The use of ozone as ultrafiltration technique has also been shown as the most promising technique for MP removal. Finally, some future research recommendations are also put forward at the end to further enhance our understanding of the MPs induced negative effects on different life forms. The flowchart shows the interaction of MPs from water contaminated with MPs with different parts of the ecosystem and final interaction with human health.

Micro- and nanoplastic toxicity: A review on size, type, source, and test-organism implications

Polymeric wastes are among the current major environmental problems due to potential pollution and contamination. Within the spectrum of polymeric waste, microplastics (MPs) and nanoplastics (NPs) have gained ground in recent research since these particles can affect the local biota, inducing toxic effects on several organisms. Different outcomes have been reported depending on particle sizes, shape, types, and exposed organisms and conditions, among other variables. This review aimed to compile and discuss the current knowledge and possible literature gaps regarding the MPs and NPs generation and their toxicological effects as stressors, considering polymer type (as polyethylene, polypropylene, polyethylene terephthalate, polystyrene, polyvinyl chloride, or others), size (micro- or nano-scale), source (commercial, lab-synthesized, or environmental) and test organism group. In that sense, 615 publications were analyzed, among which 72 % discussed micro-sized plastics, while <28 % assayed the toxicity of NPs (<1 μm). For most polymers, MPs and NPs were commercially purchased and used without additional size reduction processes; except for polyethylene terephthalate studies that mostly used grinding and cutting methods to obtain MPs. Polystyrene (PS) was the main polymer studied, as both MPs and NPs. PS accounts for >90 % of NPs reports evaluated, reflecting a major literature gap if compared to its 35.3 % share on MPs studies. Among the main organisms, arthropods and fish combined accounted for nearly 40 % of toxicity testing. Overall, the different types of plastics showed a tendency to report toxic effects, except for the 'Survival/lethality' category, which might indicate that polymeric particles induce mostly sublethal toxic effects. Furthermore, despite differences in publication numbers, we observed greater toxicity reported for NPs than MPs with oxidative stress among the majorly investigated endpoints. This study allowed a hazard profile overview of micro/nanoplastics (MNPs) and the visualization of literature gaps, under a broad diversity of toxicological evidence.

Carbon-based single-atom catalysts in advanced oxidation reactions for water remediation: From materials to reaction pathways

Single-atom catalysts (SACs) have been widely recognized as state-of-the-art catalysts in environment remediation because of their exceptional performance, 100% metal atomic utilization, almost no secondary pollution, and robust structures. Most recently, the activation of persulfate with carbon-based SACs in advanced oxidation processes (AOPs) raises tremendous interest in the degradation of emerging contaminants in wastewater, owning to its efficient and versatile reactive oxidant species (ROS) generation. However, the comprehensive and critical review unraveling the underlying relationship between structures of carbon-based SACs and the corresponding generated ROS is still rare. Herein, we systematically summarize the fundamental understandings and intrinsic mechanisms between single metal atom active sites and produced ROS during AOPs. The types of emerging contaminants are firstly elaborated, presenting the prior pollutants that need to be degraded. Then, the preparation and characterization methods of carbon-based SACs are overviewed. The underlying material structure-ROS type relationship in persulfate-based AOPs is discussed in depth to expound the catalytic mechanisms. Finally, we briefly conclude the current development of carbon-based SACs in AOPs and propose the prospects for rational design and synthesis of carbon-based SACs with on-demand catalytic performances in AOPs in future research.

Impact of plastic film mulching on microplastic in farmland soils in Guangdong province, China

Plastic mulch film is often believed to be a significant contributor to microplastic pollution in farmland soil, however, its direct impact in areas with high human activities remains unclear due to the presence of multiple pollution sources. This study aims to address this knowledge gap by investigating the impact of plastic film mulching on microplastic pollution in farmland soils in Guangdong province, China's largest economic province. The macroplastic residues in soils were investigated in 64 agricultural sites, and the microplastics were analyzed in typical plastic film mulched and nearby non-mulched farmland soils. The average concentration of macroplastic residues was 35.7 kg/ha and displayed a positive correlation with mulch film usage intensity. Contrarily, no significant correlation was found between macroplastic residues and microplastics, which exhibited an average abundance of 22,675 particles/kg soil. The pollution load index (PLI) model indicated that the microplastic pollution level was category I and comparatively higher in mulched farmland soils. Interestingly, polyethylene accounted for only 2.7% of the microplastics, while polyurethane was found to be the most abundant microplastic. According to the polymer hazard index (PHI) model, polyethylene posed a lower environmental risk than polyurethane in both mulched and non-mulched soils. These findings suggest that multiple sources other than plastic film mulching primarily contribute to microplastic pollution in farmland soils. This study enhances our understanding of microplastic sources and accumulation in farmland soils, offering crucial information on potential risks to the agroecosystem.

Impact of Human Activities on Disease-Spreading Mosquitoes in Urban Areas

Urbanization is one of the leading global trends of the twenty-first century that has a significant impact on health. Among health challenges caused by urbanization, the relationship of urbanization between emergence and the spread of mosquito-borne infectious diseases (MBIDs) is a great public health concern. Urbanization processes encompass social, economic, and environmental changes that directly impact the biology of mosquito species. In particular, urbanized areas experience higher temperatures and pollution levels than outlying areas but also favor the development of infrastructures and objects that are favorable to mosquito development. All these modifications may influence mosquito life history traits and their ability to transmit diseases. This review aimed to summarize the impact of urbanization on mosquito spreading in urban areas and the risk associated with the emergence of MBIDs. Moreover, mosquitoes are considered as holobionts, as evidenced by numerous studies highlighting the role of mosquito-microbiota interactions in mosquito biology. Taking into account this new paradigm, this review also represents an initial synthesis on how human-driven transformations impact microbial communities in larval habitats and further interfere with mosquito behavior and life cycle in urban areas.

A review on mechanistic understanding of microplastic pollution on the performance of anaerobic digestion

Anaerobic digestion (AD) has emerged as a promising technology for diverting the organic waste from the landfills along with the production of clean energy. AD is a microbial-driven biochemical process wherein the plethora of microbial communities participate in converting the putrescible organic matter into biogas. Nevertheless, the AD process is susceptible to the external environmental factors such as presence of physical (microplastics) and chemical (antibiotics, pesticides) pollutants. The microplastics (MPs) pollution has received recent attention due to the increasing plastic pollution in terrestrial ecosystems. This review was aimed for holistic assessment of impact of MPs pollution on AD process to develop efficient treatment technology. First, the possible pathways of MPs entry into the AD systems were critically evaluated. Further, the recent literature on the experimental studies pertaining to the impact of different types of MPs at different concentrations on the AD process was reviewed. In addition, several mechanisms such as direct exposure of MPs on the microbial cells, indirect impact of MPs through the leaching of toxic chemicals and reactive oxygen species (ROS) formation on AD process were elucidated. Besides, the risk possessed by the increase of antibiotic resistance genes (ARGs) after the AD process due to the MPs stress on microbial communities were discussed. Overall, this review deciphered the severity of MPs pollution on AD process at different levels.

Potential translocation process and effects of polystyrene microplastics on strawberry seedlings

A growing body of concerns focuses on microplastics as an emerging threat to terrestrial soil-plant ecosystems, but few previous studies have concentrated on asexual plants. To fill this knowledge gap, we carried out a biodistribution study of polystyrene microplastics (PS-MPs) of different particle sizes in strawberry (Fragaria × ananassa Duch. cv. "Akihime") seedlings via the hydroponic cultivation method. Confocal laser scanning microscopy (CLSM) results indicated that both 100 and 200 nm PS-MPs entered the roots and were further translocated to the vascular bundle through the apoplastic pathway. Both PS-MP sizes were detected in the vascular bundles of the petioles after 7 d of exposure, indicating a xylem-based upward translocation pathway. After 14 d, continuous upward translocation of 100 nm PS-MPs was observed above the petiole, while 200 nm PS-MPs could not be directly observed in the strawberry seedlings. This means that the uptake and translocation of PS-MPs depended on the size of PS-MPs and appropriate timing. The significant influence of strawberry seedling's antioxidant, osmoregulation, and photosynthetic systems（p < 0.05）was presented at 200 nm PS-MPs than 100 nm PS-MPs. Our findings provide scientific evidence and valuable data for the risk assessment of PS-MP exposure in asexual plant systems such as strawberry seedlings.

Potential impact of polyethylene microplastics on the growth of water spinach (Ipomoea aquatica F.): Endophyte and rhizosphere effects

Microplastic contamination has received much attention, especially in agroecosystems. However, since edible crops with different genetic backgrounds may present different responses to microplastics, more research should be conducted and focused on more edible crops. In the current study, pot experiments were conducted to investigate the potential impact of polyethylene microplastic (PE) (particle sizes: 0.5 μm and 1.0 μm, addition levels: 0 (control), 0.5% and 1.0% (w/w)) addition on the physiological and biochemical variations of I. aquatica F.. The results indicated that PE addition caused an increase in the soil pH and NH₄⁺-N and soil organic matter contents, which increased by 10.1%, 29.9% and 50.1% when PE addition at A10P0.5 level (10 g (PE) kg^-1 soil, particle size: 0.5 μm). While, PE exposure resulted in a decrease in soil available phosphorus and total phosphorus contents, which decreased by 53.9% and 10.5% when PE addition at A10P0.5 level. In addition, PE addition altered the soil enzyme activities. Two-way ANOVA indicated that particle size had a greater impact on the variations in soil properties and enzyme activities than the addition level. PE addition had a strong impact on the rhizosphere microbial and root endophyte community diversity and structure of I. aquatica F.. Two-way ANOVA results indicated that the particle size and addition level significantly altered the α-diversity indices of both rhizosphere microbial and root endophyte (P < 0.05, P < 0.01 or P < 0.001). Moreover, PE was adsorbed by I. aquatica F., which was clearly observed in the transverse roots and significantly increased the H₂O₂, ·O₂^-, malondialdehyde and ascorbic acid contents in both the roots and aerial parts of I. aquatica F., leading to a decrease in I. aquatica F. biomass. Overall, the current study enriches the understanding of the effect of microplastics on edible crops.

First evidence of meso- and microplastics on the mangrove leaves ingested by herbivorous snails and induced transcriptional responses

Although evidence suggests the ubiquity of meso- and microplastics (MMPs) in mangrove forests, our knowledge of their bioavailability and risk on mangrove leaves is scarce. Here, we investigated MMP contamination concerning submerged mangrove leaves and herbivorous snails that mainly feed on them from the four mangrove forests located in Beibu Gulf, Guangxi Province, China. Results showed that the MMP abundance on the mangrove leaves ranged from 0.01 ± 0.00 to 0.42 ± 0.15 items cm^-2, while it ranged from 0.33 ± 0.21 to 6.20 ± 2.91 items individual^-1 in the snails. There were significant positive correlations between snails and leaves regarding the abundance of total MMPs and the proportions of MMPs with the same characteristics. Expanded polystyrene (EPS) that mainly derived from aquaculture rafts, accounted for a major component both on the leaves and in the snails in Shi Jiao (SJ). Both the detection frequency and percentage of larger EPS (2.00-17.50 mm) on the leaves in SJ were higher than other sites. Meanwhile, the detection frequency, abundance and percentage of larger EPS on the leaves had significant positive correlations with those of micro-EPS in the snails. These findings suggested that mangrove leaves may represent a viable pathway for MMPs to enter the herbivorous snails. Larger EPS with higher frequency of occurrence on mangrove leaves were more likely to be encountered and ingested by snail considering its opportunistic feeding behavior. In addition, 11 sensitive genes involved in the processes of metabolism, intestinal mucosal immune systems, and cellular transduction in the snails were significantly suppressed by MMP exposure, which may be potentially used as early biomarkers to indicate the biological effects of MMPs under realistic environmental conditions. Overall, this study provides novel insights into the fate, sources, and biological effects of MMPs on mangrove leaves.

Microplastics contamination and characteristics of agricultural groundwater in Haean Basin of Korea

The quality of groundwater is critical to human health. MPs have access to groundwater from the soil, polluted by various agricultural activities. However, to date, there have been no studies on the occurrence of MP in groundwater from an agriculture field without any adjacent sources of contamination, such as nearby landfills. In this study, the occurrence and distribution of MPs in groundwater of an agricultural area in the Haean Basin, Korea, without any definite source of pollution, was examined. MP and groundwater samplings were conducted in the dry season in 2020, the wet and dry seasons in 2021, respectively. In this study, the reliability of MP analysis was improved through good practices from laboratory to field campaigns, collecting large groundwater samples (300-500 L) volumes. Any involvement of plastic materials was avoided during the full procedures as possible and. Detailed investigation was conducted for the distribution of potential plastics sources like mulching, plastic covers, dripping pipes and shading nets, and hydrogeological properties affecting MPs occurrence. Groundwater MP concentrations of 0.02-0.15 particles/L (median = 0.06 particles/L), 0.02-2.56 particles/L (median = 0.43 particles/L) and 0.20-3.48 particles/L (median = 0.83 particles/L) were found in three rounds of sampling that comprised of the exploratory investigation in 2020, the wet season, and the dry season in 2021, respectively. The identified polymer types were polypropylene (PP), polyethylene (PE), polyvinyl chloride (PVC), polystyrene (PS) and polyamide (PA). The MPs concentrations showed no statistically significant seasonal variation but revealed an apparent strong positive correlation (r = 0.71) of MPs with the amount of groundwater use. Findings of this study need more clarification from repeated samplings for multiple years. This study reveals the occurrence of MPs in groundwater in Korea for the first time to the best of our knowledge.

Microplastics in terrestrial ecosystem: Sources and migration in soil environment

Plastics, especially microplastics in soils, are considered a severe environmental issue worldwide. However, globally, the main research focus is on microplastic pollution in the marine environment, the microplastic pollution on soils and sediments remains on the sideline so far. But the fact is that microplastics are omnipresent in terrestrial systems in the form of microbeads in industrial systems and in sewage sludge. Their presence in agricultural soils and sediments is enormously increased due to plastic mulching, plastic greenhouses and compost and extensive use of controlled release fertilizers. Therefore, this review outlines the global scenario regarding plastics and microplastics production, consumption, and possible pathways of penetration into the soil environment. Various mechanisms to restrict and manage the pathways of plastics and microplastics into the soil environment are also discussed. This review also focuses on the challenges and limitations on the use of plastic alternates such as bioplastics and oxo plastics. Also, the knowledge gaps on the source of microplastics in the environment and their deleterious effects on properties of soil, soil health and focused light on their soil trophic transfer in food chains via plants. This review provides a detailed insight on the management and possible control measures to alleviate the potential risk caused by microplastics pollution in the soil environment and the overall ecosystem's health. In spite of the occurrence and fate of microplastics on terrestrial environment, knowledge gaps and challenges for tackling this contamination are also explored which facilitates the policy makers to develop regulatory measures towards the containment of microplastics in living ecosystem.

Regional Regression Correlation Model of Microplastic Water Pollution Control Using Circular Economy Tools

Water pollution caused by microplastics represents an important challenge for the environment and people's health. The weak international regulations and standards in this domain support increased water pollution with microplastics. The literature is unsuccessful in establishing a common approach regarding this subject. The main objective of this research is to develop a new approach to necessary policies and ways of action to decrease water pollution caused by microplastics. In this context, we quantified the impact of European water pollution caused by microplastics in the circular economy. The main research methods used in the paper are meta-analysis, statistical analysis and an econometric approach. A new econometric model is developed in order to assist the decision makers in increasing efficiency of public policies regarding water pollution elimination. The main result of this study relies on combining, in an integrated way, the Organisation for Economic Co-operation and Development's (OECD) data on microplastic water pollution and identifying relevant policies to combat this type of pollution.

The Road to Sustainable Tire Materials: Current State-of-the-Art and Future Prospectives

The development of a 100% sustainable tire has emerged as a milestone for several tire companies across the globe. It has created new commercial opportunities for the biobased, renewable, and recycled polymer materials. However, there are concerns that the incorporation of such sustainable new materials may have an undesirable impact on the main performance properties of the tire. At the same time, with new capabilities and product innovations, it can help us meet society's need in a more sustainable fashion and protect the environment. This Feature first outlines the opportunities and need for sustainable tire materials. Next, it describes the main types of sustainable material attributes in tire material, elastomers, reinforcing agents, fibers, and plasticizers, among a few others. The challenges to achieving the performance properties are discussed with possible design guidelines. Recent approaches to the tire attributes are described in the form of a meticulous overview of the existing literature, with a critical analysis of some of them. This contribution attempts to highlight, in a comprehensive way, sustainable tire materials on the basis of recent research advancements, existing challenges, and prospective future scope in this field.

Fourier Transform Infrared Spectroscopy to Assess the Degree of Alteration of Artificially Aged and Environmentally Weathered Microplastics

Fourier transform infrared (FTIR) is a spectroscopy technique widely used to identify organic materials. It has recently gained popularity in microplastic (MP) pollution research to determine the chemical composition of unknown plastic fragments. However, it could also be used to evaluate the degree of ageing of MPs collected from the environment. In this context, the principal aim of our research has been to qualitatively evaluate the natural weathering of environmental MPs collected in an Italian freshwater body (the Ofanto River) using ATR-FTIR technology. Furthermore, we compared environmental particles to weathered artificial MPs under controlled light and temperature conditions and to unaltered pristine materials to assess the results. FTIR spectra were acquired using a Nicolet Summit FTIR (ThermoFisher Scientific) equipped with an Everest ATR with a diamond Crystal plate and a DTGS KBr detector (wavenumber range 4000-500 cm^-1, 32 scans per spectrum, spectral resolution of 4 cm^-1). The degree of ageing was assessed using three different indexes known to be related to changes in MPs: Carbonyl Index (CI), Hydroxyl Index (HI), and Carbon-Oxygen Index (COI). The overall results showed that the regions reflecting changes (hydroxyl groups, peaks from 3100 to 3700 cm^-1, alkenes or carbon double bonds, 1600 and 1680 cm^-1, and carbonyl groups, 1690 and 1810 cm^-1) appeared significantly modified in artificial and natural weathered particles compared to the pristine materials. The indexes calculated for polymers degraded under the artificial photo and thermo ageing conditions displayed a general tendency to increase with the time in contact with irradiation time. Particular enhancements of CI of PS fragment and PE pellet, HI of PE and PS fragments and PE pellet, and COI of PS fragment were observed. Otherwise, the following incubation of the same particles at a constant temperature of 45 °C did not further affect the chemical composition of the particles. Moreover, new unique peaks were also observed in the freshwater particles, almost all in the fingerprint region (1500-500 cm^-1). Differences in CI, HI, and COI were evidenced among the different morphological MP shapes. On the one hand, the CI calculated for the environmental PE pellets showed values ranging from 0.05 to 0.26 with a mean value of 0.17 ± 0.10. Most samples (57%) presented a CI with values between 0.16 and 0.30. On the other hand, fragments presented slicer modifications in the carbonyl region with CI values lower than pellets (0.05 ± 0.05). This index helps evaluate the degradation of PE MPs by UV light, increasing with enhancing residence time in the environment. Conversely, fragments showed greater values of HI (5.90 ± 2.57) and COI (1.04 ± 0.48) than pellets, as well as lines, which presented the maximum value of HI (11.51). HI is attributed to the bond vibrations of hydroxyl, carboxyl, or phenol groups. In contrast, COI is frequently attributed to the vibrations of C_O bonds found in carbohydrates, alkanes, secondary alcohols, and ketones. In conclusion, our results showed characteristics spectra acquired from environmental particles compared to pristine and artificial aged ones. The interpretation of our main results emphasizes the need to conduct ecotoxicological experimental studies using naturally weathered particles due to the unicity of their properties, which are more helpful for understanding microplastic pollution effects.

Microplastics in urban catchments: Review of sources, pathways, and entry into stormwater

Urban areas play a key role in the production of microplastics (MPs) and their entry into water bodies. This article reviews the literature on the sources, transport, and control of MPs in urban environments with the aim of clarifying the mechanisms underlying these processes. Major MP sources include atmospheric deposition, micro-litter, and tire and road wear particles (TRWPs). MPs deposited from the atmosphere are mostly fibers and may be particularly important in catchments without traffic. Littering and attrition of textiles and plastic products is another important MP source. However, the quantities of MPs originating from this source may be hard to estimate. TRWPs are a significant source of MPs in urban areas and are arguably the best quantified source. The mobilization of MPs in urban catchments is poorly understood but it appears that dry unconsolidated sediments and MP deposits are most readily mobilized. Sequestration of MPs occurs in green areas and is poorly understood. Consequently, some authors consider green/pervious parts of urban catchments to be MP sinks. Field studies have shown that appreciable MP removal occurs in stormwater quality control facilities. Street cleaning and snow removal also remove MPs (particularly TRWPs), but the efficacy of these measures is unknown. Among stormwater management facilities, biofiltration/retention units seem to remove MPs more effectively than facilities relying on stormwater settling. However, knowledge of MP removal in stormwater facilities remains incomplete. Finally, although 13 research papers reported MP concentrations in stormwater, the total number of field samples examined in these studies was only 189. Moreover, the results of these studies are not necessarily comparable because they are based on relatively small numbers of samples and differ widely in terms of their objectives, sites, analytical methods, size fractions, examined polymers, and even terminology. This area of research can thus be considered "data-poor" and offers great opportunities for further research in many areas.

Airborne microplastics: Occurrence, sources, fate, risks and mitigation

This paper serves to enhance the current knowledge base of airborne microplastics which is significantly smaller than that of microplastics in marine, freshwater and terrestrial environments. It systematically presents the prevalence, sources, fate, risks and mitigations of airborne microplastics through the review of >140 scientific papers published mainly in the last 10 years. Unlike the extant review, it places an emphasis on the indoor microplastics, the risks of airborne microplastics on animals and plants and their mitigations. The outdoor microplastics are mostly generated by the wear and tear of tires, brake pads, waste incineration and industrial activities. They have been detected in many regions worldwide at concentrations ranging from 0.3 particles/m³ to 154,000 particles/L of air even in the Pyrenees Mountains and the Arctic. As for indoor microplastics, the reported concentrations range from 1 piece/m³ to 9900 pieces/m²/day, and are frequently higher than those of the outdoor microplastics. They come from the wear and tear of walls and ceilings, synthetic textiles and furniture finishings. Airborne microplastics could be suspended and resuspended, entrapped, settle under gravity as well as interact with chemicals, microorganisms and other microplastic particles. In the outdoors, they could also interact with sunlight and be carried by the wind over long distance. Airborne microplastics could adversely affect plants, animals and humans, leading to reduced photosynthetic rate, retarded growth, oxidative stress, inflammatory responses and increased cancer risks in humans. They could be mitigated indirectly through filters attached to air-conditioning system and directly through source reduction, regulation and biodegradable substitutes.

Size-independent quantification of nanoplastics in various aqueous media using surfaced-enhanced Raman scattering

In this work, we successfully developed an intriguing preparation strategy to reduce the size-dependent effect of nanoplastics (NPLs), which is the limitation of NPLs quantification by surface-enhanced Raman scattering (SERS). This simple and low-cost technique enabled us to quantify different sizes (i.e., 100, 300, 600, and 800 nm) of polystyrene nanospheres (PS NSs) in various aqueous media. The SERS substrate was simply prepared by sputtering gold particles to cover on a glass cover slide. By dissolving PS NSs in toluene and preconcentrating by coffee-ring effect, SERS measurement can quantify NPLs at a very low concentration with a limit of detection (LOD) of approximately 0.10-0.26 μg/mL. The experiment was also conducted in the presence of interferences, including salts, sugars, amino acids, and detergents. The method was validated for quantitative analysis using a mixture of 100-, 300-, 600-, and 800-nm PS NSs in a ratio of 1:1:1:1 in real-world media (i.e., tap water, mineral water, and river water), which successfully approaches the evaluation of PS NSs in the range of 10-40 µg/mL with an LOD of approximately 0.32-0.52 µg/mL.

Nanoplastics in the soil environment: Analytical methods, occurrence, fate and ecological implications

Soils play a very important role in ecosystems sustainability, either natural or agricultural ones, serving as an essential support for living organisms of different kinds. However, in the current context of extremely high plastic pollution, soils are highly threatened. Plastics can change the chemical and physical properties of the soils and may also affect the biota. Of particular importance is the fact that plastics can be fragmented into microplastics and, to a final extent into nanoplastics. Due to their extremely low size and high surface area, nanoplastics may even have a higher impact in soil ecosystems. Their transport through the edaphic environment is regulated by the physicochemical properties of the soil and plastic particles themselves, anthropic activities and biota interactions. Their degradation in soils is associated with a series of mechanical, photo-, thermo-, and bio-mediated transformations eventually conducive to their mineralisation. Their tiny size is precisely the main setback when it comes to sampling soils and subsequent processes for their identification and quantification, albeit pyrolysis coupled with gas chromatography-mass spectrometry and other spectroscopic techniques have proven to be useful for their analysis. Another issue as a consequence of their minuscule size lies in their uptake by plants roots and their ingestion by soil dwelling fauna, producing morphological deformations, damage to organs and physiological malfunctions, as well as the risks associated to their entrance in the food chain, although current conclusions are not always consistent and show the same pattern of effects. Thus, given the omnipresence and seriousness of the plastic menace, this review article pretends to provide a general overview of the most recent data available regarding nanoplastics determination, occurrence, fate and effects in soils, with special emphasis on their ecological implications.

Quantitative assessment of additive leachates in abiotic weathered tire cryogrinds and its application to tire wear particles in roadside soil samples

Tire and road wear particles (TRWP) are becoming an important research question with potential risks on ecological system. A comprehensive understanding of their detection and quantification in soils are challenged by the inherent technological inconsistencies, lack of well-set standardized methods, and generalized protocols. Reference tire cryogrinds were subjected to abiotic weathering. Next, the total environmental availability from parent elastomers and the release of additives from tire tread compounds were evaluated using mass concentration factors obtained from abiotic weathered tire cryogrinds. Headspace Gas chromatography-mass spectroscopy (HS-GC-MS) was employed as a nontargeted, suspect screening analysis technique to identify the tire related intermediates. Benzothiazole, 1,2-dihydro-2,2,4-trimethylquinoline (TMQ), aniline, phenol and benzoic acid were detected as tire tetrahydrofuran leachates. Total environmental availability of TMQ and benzothiazole were in the range of 1.7 × 10-3 and 0.11, respectively. Benzene and benzoic acid derivatives were identified as marker compounds for environmental samples. A TRWP content evaluation was made possible by quantifying marker concentrations and reference tire cryogrind formulation. TRWP content in the size range of 1-5 mm was between 800 and 1300 μg/g and 1200-3100 μg/g TRWP in Ohio and Kansas soil. For TRWP less than 1 mm, 0.15-2.1 wt% content was observed in Kansas and Ohio samples and were seemingly dependent on the locations and the traffic. This simple, widely applicable quantification method for TRWP analysis provides a database of tire degradation and TRWP intermediates. The TRWP content research is critical for further TRWP research development in terrestrial environment.

Microplastic contamination in terrestrial ecosystems: A study using barn owl (Tyto alba) pellets

Microplastics (MPs) are recognised as an emerging environmental problem that needs to be carefully monitored. So far, MPs have been widely recorded in marine and freshwater ecosystems. Still, few studies have focused on MP occurrence in terrestrial ecosystems, although soils are suspected to be one of the main MP reservoirs. To test a non-invasive method for assessing MP contamination in terrestrial ecosystems, we analysed the pellets of a top terrestrial predator, the barn owl (Tyto alba). Sixty pellets were collected from three agricultural areas (20 pellets each) and analysed to assess both barn owl diet and MP content. Thirty-four MPs were confirmed by micro-Fourier Transform Infrared Spectroscopy (μ-FTIR) analysis in 33% of the pellets (min-max 1-5 MPs per pellet). Most of the detected items were microfibres (88.2%). Polyethylene terephthalate, polyacrylonitrile and polyamide were the most abundant polymers. One of the three sites was significantly less contaminated. In the two sites with the highest MP occurrences, barn owl diet was characterised by predation on synanthropic rodents, particularly brown rats (Rattus norvegicus), which may indicate habitat degradation and increased exposure to MPs. Analyses also suggest that Savi's pine vole (Microtus savii) is the prey least at risk of MP contamination, probably due to its strictly herbivorous diet. We argue that the analysis of barn owl pellets may represent a cost-effective method for monitoring MP contamination in terrestrial ecosystems.

Root Vegetables-Composition, Health Effects, and Contaminants

Root vegetables are known all over the world, but they are being less and less consumed by individuals. The main purpose of this article was to summarize the benefits, health effects, and threats associated with the consumption of carrot, celery, parsley, beetroot, radish, turnip, and horseradish. They are characterized by high nutritional value due to their richness in dietary fiber, vitamins, and minerals. One of their most important features is their high content of bioactive compounds, such as polyphenols, phenols, flavonoids, and vitamin C. These compounds are responsible for antioxidant potential. Comparison of their antioxidant effects is difficult due to the lack of standardization among methods used for their assessment. Therefore, there is a need for a reference method that would allow for correct interpretation. Moreover, root vegetables are characterized by several health-promoting effects, including the regulation of metabolic parameters (glucose level, lipid profile, and blood pressure), antioxidant potential, prebiotic function, and anti-cancer properties. However, due to the type of cultivation, root vegetables are vulnerable to contaminants from the soil, such as toxic metals (lead and cadmium), pesticides, pharmaceutical residues, microplastics, and nitrates. Regardless, the low levels of toxic substances present in root vegetables do not pose health risks to the average consumer.

Microplastics in urban runoff: Global occurrence and fate

Public concerns on microplastic (MP) pollution and its prevalence in urban runoff have grown exponentially. Huge amounts of MPs are transported from urban environments via surface runoff to different environment compartments, including rivers, lakes, reservoirs, estuaries, and oceans. The global concentrations of MPs in urban runoff range from 0 to 8580 particles/L. Understanding the sources, abundance, composition and characteristics of MPs in urban runoff on a global scale is a critical challenge because of the existence of multiple sources and spatiotemporal heterogeneity. Additionally, dynamic processes in the mobilization, aging, fragmentation, transport, and retention of MPs in urban runoff have been largely overlooked. Furthermore, the MP flux through urban runoff into rivers, lakes and even oceans is largely unknown, which is very important for better understanding the fate and transport of MPs in urban environments. Here, we provide a critical review of the global occurrence, transport, retention process, and sinks of MPs in urban runoff. Relevant policies, regulations and measures are put forward. Future global investigations and mitigation efforts will require us to address this issue cautiously, cooperating globally, nationally and regionally, and acting locally.

Physiological response and oxidative stress of grass carp (Ctenopharyngodon idellus) under single and combined toxicity of polystyrene microplastics and cadmium

The harm of microplastics (MPs) to aquatic ecosystems is caused by their stable and non-degradable properties. Additionally, the pollutants such as heavy metals in the water are easy to be adsorbed on their surface with their small particle size and large specific surface area, resulting in environmental pollution. Therefore, the study on the mixture toxicity of MPs and heavy metals has theoretical significance for the risk assessment of aquatic ecosystems. In the present study, 10 nm polystyrene (PS) and cadmium (Cd) were used, and their individual and mixture acute toxicities on grass carp (Ctenopharyngodon idellus) were examined. The results indicated that the mortality of the fish increased with the concentration from 10 mg L^-1 to 20 mg L^-1, and the existence of PS-MPs elevated the Cd concentrations in the fish and accelerated the death. Whether the Cd and/or the PS-MPs concentrations caused varying degrees of damage to the gills, kidney, liver, and muscles of the grass carp, especially under the highest concentrations (20 mg L^-1 Cd + 300 μg L^-1 PS-MPs). Moreover, low concentrations of PS-MPs alone (30 μg L^-1 PS-MPs) significantly increased the superoxide dismutase (SOD) activity in the kidney and liver, reaching 12.43% and 14.38%, respectively (P < 0.05). The peroxidase (POD) activity was increased only in the kidney, up to 25.95% (P < 0.05). Also, significant reductions in SOD and POD activities were observed in the combination of high concentration of Cd (20 mg L^-1) and 300 μg L^-1 PS-MPs (P < 0.05). To the best of our knowledge, there are few studies on the impact of combined toxicity of PS-MPs and Cd on grass carp under laboratory conditions. Therefore, these findings may provide a theoretical guarantee for pollution prevention and control in the aquatic ecosystem.

The assessment of particle selection and blank correction to enhance the analysis of microplastics with Raman microspectroscopy

Although microplastics research has received enormous attention in the last decade, both the research practices and the quality of produced data should still be improved. In this study, the identification process of microplastics with Raman imaging microscope was improved by decreasing the time needed for the analysis. To do that, new features, including terrain mosaic and automatic particle selection, were utilized and various ways of handling the produced microplastics data were implemented and discussed. Furthermore, blank correction of microplastic concentrations was demonstrated and its effects on the recovery of spiked microplastics was assessed with aqueous and solid samples. Six types of microplastics, including fragments and fibers, were spiked in triplicates of ultra-pure water and reference sediment samples. The spiked samples were pretreated by a modified method of the universal enzymatic purification protocol. Microplastics were analyzed with Raman imaging microscope, using terrain mosaic combined with automatic particle selection. The microplastics data were subjected to different identification steps to estimate the potential overestimation and underestimation of microplastics counts. With the complete correction of Raman-based data, the average recovery rates of fragments (77-80%) were higher than fibers (20-33%). The decrease in recovery rates of spiked microplastics (49-57%) were observed when blank correction was applied (28-47%). The impact of the blank correction depended on the polymer, causing exclusion of PE, PET, and PP from sediment samples. For the completely corrected Raman-based data, the average recovery rates of microplastics were higher for water than sediment samples both with and without blank correction. The results demonstrated the impact of blank correction on the microplastics recovery rates. To our knowledge, this is the first study to explore the use of automatic particle selection of Raman imaging microscope for microplastics analysis. Hence, potential drawbacks and advantages of the new features of Raman imaging microscope were explicitly discussed.

Assessment of metals associated with virgin pre-production and freshwater microplastics collected by an Italian river

Recently, microplastics (MPs) have been detected in almost all environmental matrices (water, soil, air, biota). Their presence is of concern due to high environmental persistence and their ability to release or bind pollutants. In light of this, the present work aimed to quantify a poorly studied pollutant category associated with MPs: metals. This analysis was conducted on virgin MPs, used as raw materials in the plastics' production process and on environmental MPs taken from the Ofanto river in Southern Italy. The MP samples were initially grouped for colour, shape and ageing and following mineralised by a microwave digestor. The metals and metalloids Pb, Ba, Sb, Sn, Cd, Mo, Se, Zn, Cu, Ni, Co, Cr, Fe, Mn, Ti, Al, V, Ca, K, Mg, Na were subsequently quantified with ICP-MS. All the analysed elements were found on both types of samples (virgin and environmental MPs), with higher concentrations detected on environmental samples (above 14,400 μg/g^-1) rather than on pristine ones (above 5000 μg/g^-1). Many of these inorganic compounds are probably adsorbed by the surrounding environment, and others are intentionally added during the plastic production process to improve their properties (e.g. additives). Noticeable differences were detected concerning the metal's distribution and amount observed in the two types of MP particles analysed. Moreover, trace element concentrations were also linked to the colour and shape of the environmental particles analysed. Most abundant levels of metals were quantified on aged black fragments, followed by coloured and transparent fragments and black pellets. Our concluding remarks underline the role of MPs as a vehicle for the transport of metals, with significant differences between the high abundance of these pollutants examined in our particles collected in a freshwater environment and the significantly lower concentrations revealed previously in marine MPs.

Airborne Microplastic in the Atmospheric Deposition and How to Identify and Quantify the Threat: Semi-Quantitative Approach Based on Kraków Case Study

Airborne microplastic is an emerging and widespread pollutant yet is still under-characterised and insufficiently understood. Detailed description of microplastic air pollution is crucial as it has been identified in human lungs and remote locations, highlighting the atmosphere as a medium of MP dispersion and transportation. The lack of standardization of methods for measuring and further monitoring of microplastic pollution is an obstacle towards assessment of health risks. Since the first recognition of MP presence in the atmosphere of Krakow in 2019, this research was conducted to further characterise and develop the methods for qualitative and quantitative analysis of airborne microplastic (attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR); pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS); scanning electron microscopy-energy dispersive spectroscopy SEM-EDS) and pre-treatment of samples. The data were gathered in seven cycles from June 2019 to February 2020. The methods used in the study allowed the identification and analysis of the changing ratio of the different types of synthetic polymers identified in the atmospheric fallout (low-density polyethylene, nylon-66, polyethylene, polyethylene terephthalate, polypropylene and polyurethane). Observations of interactions between microplastic particles and the environment were conducted with analyses of surface changes due to degradation. Different phases attached to the microplastics surfaces, with some of the inorganic contaminants transported on these surfaces determined also to be of anthropogenic origin. The methodology proposed in this study allows further characterisation of microplastic from multiple locations to provide highly comparable data, leading to identification of the sources of this phenomenon, as well as seasonal changes.

Microplastics can affect soil properties and chemical speciation of metals in yellow-brown soil

Although the influence of microplastics (MPs) in different soil environments has been investigated, their effects on the physiochemical properties and chemical speciation of heavy metals in yellow-brown soil remains unknown. This study aimed to determine the effects of various concentrations of linear low-density polyethylene (LLDPE), polyamide (PA), polyurethane (PU), polystyrene (PS), and low-density polyethylene (LDPE) MPs on the yellow-brown soil environment and chemical speciation of the heavy metals cadmium (Cd), copper (Cu), lead (Pb), and zinc (Zn). MPs influenced the physicochemical properties and chemical speciation of heavy metals in yellow-brown soil. The physicochemical properties of yellow-brown soil can be altered by changing the concentrations of LDPE MP. The relationship between changes in field capacity (FC) and LDPE concentrations was approximately linear. The physiochemical properties of yellow-brown soil containing added PA, PU, and LDPE MPs were substantially improved (control vs. MPs): FC, 39 % vs. 42.50 % for PU, cation exchange capacity (CEC) 45.77, 56.65, and 57.44 cmol.kg^-1 for PA, PU, and LDPE respectively, and organic matter (OM) content, 40.16 vs. 51.68 g.kg^-1 for PA. The LLDPE and PU MPs also simultaneously affected the chemical speciation of heavy metals in yellow-brown soil. The LLDPE MPs increased the acid-soluble (45.17-54.67 % (Cd-F1), 7.24-11.30 % (Cu-F1), 4.20-7.23 % (Pb-F1), 21.21-31.47 % (Zn-F1)) and reducible (24.02-29.41 % (Cd-F2), 25.69-34.95 % (Cu-F2), 74.29-81.07 % (Pb-F2), 28.77-34.19 % (Zn-F2)) fractions of heavy metals, which increased their bioavailability. However, PU MPs reduced the ecological risk of heavy metals in yellow-brown soil by increasing the content of the residual fraction (26.11-40.21 % (Cd-F4), 47.63-59.67 % (Cu-F4), 17.25-26.76 % (Pb-F4), 32.63-50.46 % (Zn-F4)). Changes in the properties of yellow-brown soil and the impact of MPs on heavy metals, might change the chemical speciation of heavy metals. The impact of MPs on heavy metals in yellow-brown soil requires further investigation.

The use of surrogate standards as a QA/QC tool for routine analysis of microplastics in sewage sludge

The efficient retention of microplastic particles (MP) during wastewater treatment results in their accumulation in the sewage sludge. Thus, sewage sludge represents a key matrix for understanding MP flows between engineered and natural systems. Building on previous reports, we present a sample preparation protocol optimized for digested sewage sludge. The key steps include acid digestion supported by Fenton reagents, enzymatic digestion, and density separation using sodium polytungstate (density of 1.9 gcm^-3). We use colored polyethylene (PE) spheres as surrogate standards to assess sample specific recoveries in terms of number and size, based on visible light (vis) microscopy and focal plane array - micro-Fourier transform - infrared (FPA-μ-FT-IR) imaging. The FT-IR spectra of common MP were identical before and after the digestion procedures and morphological changes were observed for polylactide fibers only. Average recovery rates for PE spheres, polypropylene fibers and polyethylene terephthalate fragments extracted from spiked digested sewage sludge and determined using (automated) vis microscopy ranged from 80% to 100%. Similar recovery rates of around 80% were also obtained for PE spheres based on FPA-μ-FT-IR measurements. The median diameters of red and blue PE spheres in dry state and recovered from spiked deionized water and from extracts of spiked digested sewage sludge determined using vis microscopy ranged between 46 μm and 67 μm. These diameters were similar to 54 μm and 61 μm obtained from the FPA-μ-FT-IR measurements of the corresponding deionized water samples and digested sludge extracts and in line with data from the producer (53 μm-63 μm). Using our digestion protocol in combination with surrogate standards, we measured MP number concentrations of around 10,000 #/g in dried, digested sewage sludge, in agreement with recent results from other studies.

Effects of polyethylene and polylactic acid microplastics on plant growth and bacterial community in the soil

Microplastics (MPs), especially biodegradable MPs (BMPs) have attracted increasing attention in recent years. However, the effects of MPs with different biodegradability on the soil-plant systems are not well explored. In this study, the effects of polyethylene MPs (PEMPs) and polylactic acid MPs (PLAMPs) on physio-biochemical performance and metabolomic profile of soybean (Glycine max), as well as the bacterial communities in soil were investigated. Our results showed that PEMPs had no noticeable toxicity on the plant growth, while 0.1% PLAMPs significantly decreased the root length by 27.53% when compared with the control. The peroxidase (POD) activity was reduced and catalase (CAT) activity was increased by MPs in plant leaves. The metabolomics study suggested that the significantly affected metabolic pathway is amino acid metabolism. Additionally, Shannon and Simpson indices of rhizosphere soil were changed only under 0.1% PLAMPs. The key bacteria involved in the dinitrogen fixation were also altered. This study provides a novel insight into the potential effects of MPs with different biodegradability on soil-plant systems and highlights that BMPs might have stronger negative effects for terrestrial ecosystem, which needs to be further explored in future research.

Visualizing and assessing the size-dependent oral uptake, tissue distribution, and detrimental effect of polystyrene microplastics in Eisenia fetida

Microplastics are widely distributed in the environment, their potential ecological risks on soil organism have attracted extensive attention, while the investigation of the size effect on its accumulation and toxicity in soil invertebrates are still lacking. In this study, we set out to explore the size-dependent effects of microplastics on soil invertebrates with different doses. Specifically, we investigated the effect of polystyrene (PS) microplastics on earthworm Eisenia fetida with three different sizes (70 nm, 1 μm and 10 μm) and exposure doses (0.5%, 5% and 10% w/w in food). Results showed that PS microplastics had no effects on the mortality of E. fetida, while an obvious growth inhibition with rising exposure concentrations was observed, especially under exposure of 70 nm plastic particles. Additionally, 70 nm PS microplastics induced more serious oxidative stress, energy depletion and histopathological damage on earthworms compared with larger sizes. The accumulation and distribution pattern of microplastics was size-dependent in earthworms after 3- and 7-day exposure as revealed by laser confocal microscopy. Notably, earthworms accumulated more micro-sized particles (MPs, 10 μm and 1 μm) but with less toxic responses, suggesting its weaker toxicity. The distribution pattern of MPs may explain the weak relation between accumulation and toxicity as they mainly distributed in epidermis of mid- and tail-section and the intestine of earthworm. In contrast, nano-sized particles (NPs, 70 nm) were more distributed in the head-section and subcutaneous tissue of the skin, which was in accordance with the obvious toxic responses found in earthworms exposing to NPs. Our study highlighted the importance of size in determining the accumulation, distribution and toxic effects of plastic particles towards soil invertebrates and advocates the necessity of ecological risk assessments of NPs.