Thorough Multianalytical Characterization and Quantification of Micro- and Nanoplastics from Bracciano Lake’s Sediments

Micro(nano)plastics from synthetic oligomers persisting in Mediterranean seawater: Comprehensive NMR analysis, concerns and origins

The presence in seawater of low-molecular-weight polyethylene (PE) and polydimethylsiloxane (PDMS), synthetic polymers with high chemical resistance, has been demonstrated in this study for the first time by developing a novel methodology for their recovery and quantification from surface seawater. These synthetic polymer debris (SPD) with very low molecular weights and sizes in the nano- and micro-metre range have escaped conventional analytical methods. SPD have been easily recovered from water samples (2 L) through filtration with a nitrocellulose membrane filter with a pore size of 0.45 μm. Dissolving the filter in acetone allowed the isolation of the particulates by centrifugation followed by drying. The isolated SPD were analysed by 1H nuclear magnetic resonance spectroscopy (1H NMR), identifying PE and PDMS. These polymers are thus persisting on seawater because of their low density and the ponderal concentrations were quantified in mg/m3. This method was used in an actual case study in which 120 surface seawater samples were collected during two sampling campaigns in the Mediterranean Sea (from the Gulf of Salerno to the Gulf of Policastro in South Italy). The developed analytical protocol allowed achieving unprecedented simplicity, rapidity and sensitivity. The 1H and 13C NMR structural analysis of the PE debris indicates the presence of oxidised polymer chains with very low molecular weights. Additionally, the origin of those low molecular weight polymers was investigated by analysing influents and effluents from a wastewater treatment plant (WWTP) in Salerno as a hot spot for the release of SPD: the analysis indicates the presence of low molecular weight polymers compatible with wax-PE, widely used for coating applications, food industry, cosmetics and detergents. Moreover, the origin of PDMS debris found in surface seawater can be ascribed to silicone-based antifoamers and emulsifiers.

Microplastics and nanoplastics: Exposure and toxicological effects require important analysis considerations

Microplastics (MPs) and nanoplastics (NPs) pervade both the environment and the food chain, originating from the degradation of plastic materials from various sources. Their ubiquitous presence raises concerns for ecosystem safety, as well as the health of animals and humans. While evidence suggests their infiltration into mammalian and human tissues and their association with several diseases, the precise toxicological effects remain elusive and require further investigation. MPs and NPs sample preparation and analytical methods are quite scattered without harmonized strategies to exist at the moment. A significant challenge lies in the limited availability of methods for the chemical characterization and quantification of these contaminants. MPs and NPs can undergo further degradation, driven by abiotic or biotic factors, resulting in the formation of cyclic or linear oligomers. These oligomers can serve as indicative markers for the presence or exposure to MPs and NPs. Moreover, recent finding concerning the aggregation of oligomers to form NPs, makes their analysis as markers very important. Recent advancements have led to the development of sensitive and robust analytical methods for identifying and (semi)quantifying these oligomers in environmental, food, and biological samples. These methods offer a valuable complementary approach for determining the presence of MPs and NPs and assessing their risk to human health and the environment.

Microplastic contamination in Ashtamudi Lake, India: Insights from a Ramsar wetland

Estuaries function as temporary storage sites for plastic debris, influencing the distribution of microplastics (MPs) across ecosystems. This research delves into the presence of MPs in the water, sediment, fish, and shellfish of Ashtamudi Lake, a Ramsar wetland with brackish water located on the southwest coast of India. Given the lake's significance in supporting the livelihoods of numerous fishers and acting as a vital source of fishery resources for both local consumption and export, examining the contamination of the system by MPs becomes particularly pertinent. The highest percentage composition of MPs was found in macrofauna at 60.6% (with fish at 19.6% and shellfish at 40.9%), followed by sediment (22.8%) and water (16.7%). The primary types of MPs identified in all samples were fibers (35.6%), fragments (33.3%), and films (28%), with beads being the least represented at 3.03%. ATR-FTIR and Raman spectra analysis identified five polymers from shellfish (polypropylene, polyethylene, polystyrene, nylon, and polyvinyl chloride), five from fish guts (nylon, polypropylene, polyethylene, polyurethane, and polysiloxane), four in sediment (polypropylene, polyethylene, nylon, rayon), and four in water samples (polypropylene, polyethylene, nylon, and polystyrene). SEM-EDAX analysis of MPs obtained from the samples revealed degradation and the presence of inorganic elements such as Na, Mg, Al, Si, S, K, Cl, P, and Ca, as well as heavy metals like Pb, Mo, Rh, Pd, Ti, and Fe. The existence of these plastic polymers and heavy metals in microplastic samples poses a threat to vulnerable biota; people consume contaminated fish and shellfish, underscoring the importance of monitoring MPs in lake water. This investigation of MPs in Ashtamudi Lake highlights the system's susceptibility to plastic pollution and the bioavailability of smaller MPs to aquatic organisms. Identified sources of MPs in the lake include fishing and aquaculture activities, sewage pollution, improper solid waste management in lake watersheds, and unsustainable tourism. Upstream and downstream management interventions are recommended to address MP pollution in Ashtamudi Lake.

Effects of microplastics on microbial community dynamics in sediments from the Volturno River ecosystem, Italy

In this study, the sources, abundance, and ecological implications of microplastic (MP) pollution in Volturno, one of the main rivers in southern Italy, were explored by investigating the MP concentration levels in sediments collected along the watercourse. The samples were sieved through 5- and 2-mm sieves and treated with selective organic solvents. The polymer classes polystyrene (PS), polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), polycarbonate (PC), nylon 6 (PA6), and nylon 6,6 (PA66) were quantified using pyrolysis-gas chromatography-mass spectrometry (Py-GC/MS) and high-performance liquid chromatography (HPLC). Furthermore, a 16S rRNA metagenomic analysis was performed using next-generation sequencing in Ion Torrent™ to explore the bacterial taxonomy and ecological dynamics of sediment samples. The MPs were detected in all samples collected from the study area. PP and PET were the most abundant and frequently detected polymer types in the analysed samples. The total MP concentration ranged from 1.05 to 14.55 ppm (parts per million), identifying two distinct data populations: high- and low-MP-contaminated sediments. According to the Polymer Hazard Index (PHI), MP pollution was categorised as hazard levels III and IV (corresponding to the danger category). Metagenomic data revealed that the presence of MPs significantly affected the abundance of bacterial taxa; Flavobacteraceae and Nocardiaceae, which are known to degrade polymeric substances, were present in high-MP-contaminated sediments. This study provides new insights into the ecological relevance of MP pollution and suggests that microorganisms may serve as biomarkers of MP pollution.

Microbial colonization patterns and biodegradation of petrochemical and biodegradable plastics in lake waters: insights from a field experiment

Introduction

Once dispersed in water, plastic materials become promptly colonized by biofilm-forming microorganisms, commonly known as plastisphere.

Methods

By combining DNA sequencing and Confocal Laser Scanning Microscopy (CLSM), we investigated the plastisphere colonization patterns following exposure to natural lake waters (up to 77 days) of either petrochemical or biodegradable plastic materials (low density polyethylene - LDPE, polyethylene terephthalate - PET, polylactic acid - PLA, and the starch-based MaterBi® - Mb) in comparison to planktonic community composition. Chemical composition, water wettability, and morphology of plastic surfaces were evaluated, through Transform Infrared Spectroscopy (ATR-FTIR), Scanning Electron Microscopy (SEM), and static contact angle analysis, to assess the possible effects of microbial colonization and biodegradation activity.

Results and Discussion

The phylogenetic composition of plastisphere and planktonic communities was notably different. Pioneering microbial colonisers, likely selected from lake waters, were found associated with all plastic materials, along with a core of more than 30 abundant bacterial families associated with all polymers. The different plastic materials, either derived from petrochemical hydrocarbons (i.e., LDPE and PET) or biodegradable (PLA and Mb), were used by opportunistic aquatic microorganisms as adhesion surfaces rather than carbon sources. The Mb-associated microorganisms (i.e. mostly members of the family Burkholderiaceae) were likely able to degrade the starch residues on the polymer surfaces, although the Mb matrix maintained its original chemical structure and morphology. Overall, our findings provide insights into the complex interactions between aquatic microorganisms and plastic materials found in lake waters, highlighting the importance of understanding the plastisphere dynamics to better manage the fate of plastic debris in the environment.

Analysis of micro- and nanoplastics in wastewater treatment plants: key steps and environmental risk considerations

The analysis of micro- and nanoplastics (MNPs) in the environment is a critical objective due to their ubiquitous presence in natural habitats, as well as their occurrence in various food, beverage, and organism matrices. MNPs pose significant concerns due to their direct toxicological effects and their potential to serve as carriers for hazardous organic/inorganic contaminants and pathogens, thereby posing risks to both human health and ecosystem integrity. Understanding the fate of MNPs within wastewater treatment plants (WWTPs) holds paramount importance, as these facilities can be significant sources of MNP emissions. Additionally, during wastewater purification processes, MNPs can accumulate contaminants and pathogens, potentially transferring them into receiving water bodies. Hence, establishing a robust analytical framework encompassing sampling, extraction, and instrumental analysis is indispensable for monitoring MNP pollution and assessing associated risks. This comprehensive review critically evaluates the strengths and limitations of commonly employed methods for studying MNPs in wastewater, sludge, and analogous environmental samples. Furthermore, this paper proposes potential solutions to address identified methodological shortcomings. Lastly, a dedicated section investigates the association of plastic particles with chemicals and pathogens, alongside the analytical techniques employed to study such interactions. The insights generated from this work can be valuable reference material for both the scientific research community and environmental monitoring and management authorities.

Geographical heterogeneity and dominant polymer types in microplastic contamination of lentic ecosystems: implications for methodological standardization and future research

This study examines the prevalence and distribution of microplastic polymer types in lentic ecosystems, revealing significant heterogeneity across different geographical regions and ecosystems. The most dominant type of microplastic observed was polyethylene (PE), followed by polypropylene (PP) and polystyrene (PS), which aligns with global production rates. North America, Asia, and Europe were identified as the regions with the highest microplastic contamination, with the United States, China, Italy, and Spain being the most affected countries. The physical characteristics of each ecosystem, such as wind speed, depth, and eutrophication, alongside seasonal variations, and anthropogenic activities, contributed to the observed heterogeneity in microplastics concentrations. The study highlights the need for further research on microplastics in lentic ecosystems, considering their unique physical characteristics and anthropogenic influences. A significant lack of methodological standardization in microplastics research was identified, leading to underestimation of microplastics prevalence and high heterogeneity in meta-analyses.

Insights into Anthropogenic Micro- and Nanoplastic Accumulation in Drinking Water Sources and Their Potential Effects on Human Health

Anthropogenic microplastics (MPs) and nanoplastics (NPs) are ubiquitous pollutants found in aquatic, food, soil and air environments. Recently, drinking water for human consumption has been considered a significant pathway for ingestion of such plastic pollutants. Most of the analytical methods developed for detection and identification of MPs have been established for particles with sizes > 10 μm, but new analytical approaches are required to identify NPs below 1 μm. This review aims to evaluate the most recent information on the release of MPs and NPs in water sources intended for human consumption, specifically tap water and commercial bottled water. The potential effects on human health of dermal exposure, inhalation, and ingestion of these particles were examined. Emerging technologies used to remove MPs and/or NPs from drinking water sources and their advantages and limitations were also assessed. The main findings showed that the MPs with sizes > 10 μm were completely removed from drinking water treatment plants (DWTPs). The smallest NP identified using pyrolysis-gas chromatography-mass spectrometry (Pyr-GC/MS) had a diameter of 58 nm. Contamination with MPs/NPs can occur during the distribution of tap water to consumers, as well as when opening and closing screw caps of bottled water or when using recycled plastic or glass bottles for drinking water. In conclusion, this comprehensive study emphasizes the importance of a unified approach to detect MPs and NPs in drinking water, as well as raising the awareness of regulators, policymakers and the public about the impact of these pollutants, which pose a human health risk.

Multi-Analytical Approach to Characterize the Degradation of Different Types of Microplastics: Identification and Quantification of Released Organic Compounds

Microplastics and nanoplastics represent one of the major environmental issues nowadays due to their ubiquitous presence on Earth, and their high potential danger for living systems, ecosystems, and human life. The formation of both microplastics and nanoplastics strongly depends on both the type of pristine materials and the degradation processes related to biological and/or abiotic conditions. The aim of this study is to investigate the effect of two of the most relevant abiotic parameters, namely temperature and light, taken under direct control by using a Solar box, on five types of reference polymers: high density polyethylene (HDPE), low density polyethylene (LDPE), polypropylene (PP), polystyrene (PS), and polyethylene terephthalate (PET). A multi-analytical approach was adopted to investigate in detail the first steps of plastics degradation. Samples of plastic materials at different degradation times were analyzed by means of ¹H NMR spectroscopy and thermal desorption gas chromatography mass spectrometry (TD-GC-MS) technique. Several minor molecular species released during degradation were consistently identified by both techniques thus providing a comprehensive view of the various degradation products of these five types of microplastics.

Review on the ecotoxicological impacts of plastic pollution on the freshwater invertebrate Daphnia

The environmental impacts of plastic pollution have recently attracted universal attention, especially in the aquatic environment. However, research has mostly been focused on marine ecosystems, even though freshwater ecosystems are equally if not more polluted by plastics. In addition, the mechanism and extent to which plastic pollution affects aquatic biota and the rates of transfer to organisms through food webs eventually reaching humans are poorly understood, especially considering leaching hazardous chemicals. Several studies have demonstrated extreme toxicity in freshwater organisms such Daphnia. When such keystone species are affected by ambient pollution, entire food webs are destabilized and biodiversity is threatened. The unremitting increase in plastic contaminants in freshwater environments would cause impairments in ecosystem functions and structure, leading to various kinds of negative ecological consequences. As various studies have reported the effects on daphnids, a consolidation of this literature is critical to discuss the limitations and knowledge gaps and to evaluate the risk posed to the aquatic environment. This review was undertaken due to the evident need to evaluate this threat. The aims were to provide a meaningful overview of the literature relevant to the potential impact of plastic pollution and associated contaminants on freshwater daphnids as primary consumers. A critical evaluation of research gaps and perspectives is conducted to provide a comprehensive risk assessment of microplastic as a hazard to aquatic environments. We outlined the challenges and limitations to microplastic research in hampering better-focused investigations that could support the development of new plastic materials and/or establishment of new regulations.

Separation of false-positive microplastics and analysis of microplastics via a two-phase system combined with confocal Raman spectroscopy

In the field of microplastics research, more accurate standardised methods and analytical techniques still need to be explored. In this study, a new method for the microplastics quantitatively and qualitatively analysis by two-phase (ethyl acetate-water) system combined with confocal Raman spectroscopy was developed. Microplastics can be separated from false-positive microplastics in beach sand and marine sediment, attributing to the hydrophobic-lipophilic interaction (HLI) of the two-phase system. Results show that the recovery rates of complex environment microplastics (polypropylene (PP), polyethylene terephthalate (PET), polyvinyl chloride (PVC), polyamide 66 (PA 66), polycarbonate (PC) and polyethylene (PE)) are higher than 92.98%. Moreover, the new technique can also be used to detect hydrophobic and lipophilic antibiotics, such as sulfamethoxazole (SMX), erythromycin (EM), madimycin (MD), and josamycin (JOS), which adsorbed on microplastics and are extracted based on the dissolving-precipitating mechanism. This innovative research strategy provides a new scope for further detection of marine environment microplastics and toxic compounds adsorbed on its surface.

Distribution, sources, migration, influence and analytical methods of microplastics in soil ecosystems

Microplastics are ubiquitous in soil ecosystems all over the world through source and migration. It is even estimated that the content of microplastics in terrestrial ecosystems exceeds the number of microplastics entering sea ecosystems. However, compared with the research on microplastics in marine ecosystems, the research and discussion on microplastics in soil ecosystems are still less. Transportation, film mulching and sewage sludge are three main sources of soil microplastics. The abundance, polymer type, size and shape of the microplastics are related to the source and they help to clarify the source. The characteristics of microplastics, farming measures, soil animal activities and other factors promote the migration of microplastics, which bring new challenges to the soil ecosystems and humans. This article summarizes the latest research findings on the effects of soil microplasticity on soil properties, plants, animals and microorganisms. The analysis methods of microplastics in soil can refer to the analysis methods of microplastics of aquatic sediments, because soil and aquatic sediments are similar, both of which are complex solid substrates. At present, the development of analytical methods is limited due to the complex matrix of soil and the small volume of microplastics, which requires continuous development and innovation. Through the summary and analysis of related articles, this article reviews the distribution, sources, migration, influence and analysis methods of soil microplastics. This article also critically analyzes the deficiencies in the studies of microplastics in the soil ecosystems, and made some suggestions for future work. The microplastics in soil ecosystems need further research and summary, which will help people further understand the potential hazards of microplastics.

Spatial distribution of microplastics in volcanic lake water and sediments: Relationships with depth and sediment grain size

Microplastics (plastics <5 mm) are globally widespread pollutants of aquatic ecosystems. As microplastics contaminate both water and sediments, research on their spatial distribution in these different environmental matrices has increased. However, fresh waters are poorly studied and even less so are lentic ecosystems. To contribute filling this knowledge gap, this study analyses the distribution of microplastics in the water column and surface sediments of a volcanic lake, namely Lake Bracciano. Furthermore, it analyses in more detail the relationship between the concentration of microplastics in sediments, its grain size and the sampling depth (i.e. nearshore or deep). Water and sediment sampling was carried out in different sectors of the lake (northern, eastern, southern, western) using a plankton net and a van Veen grab sampler, respectively. Two sediment samples were collected at each station in order to analyse the abundance of microplastic and to perform grain size analysis. Results show a mean concentration of 2.4 items m^-3 in water and 42 items kg^-1 in sediments. The distribution of microplastics is uneven between the different sampling stations, with the northern sector being the most contaminated in both matrices. The chemical composition and shape of microplastics vary between water and sediment. In particular, polyethylene terephthalate and polyvinyl chloride are the most abundant polymers in water and sediments, respectively. Fibres are the main shape of microplastics in water while fragments are more abundant in sediments. In-depth analysis of sediment shows that sediments from deep stations are more contaminated than nearshore samples and have more fragment-shaped microplastics than fibre-shaped ones. Furthermore, there is a significant positive correlation between the concentration of microplastics and the abundance of silt, confirming data emerging from the scientific literature on marine and lotic ecosystems.

Assessment, characterization, and quantification of microplastics from river sediments

Microplastic (MP), as a pollutant, is currently posing a biological hazard to the aquatic environment. The study aims to isolate, quantify, and characterize the MP pollutants in sediment samples from 14 study sites at Kaveri River, Killa Chinthamani, Tiruchirappalli, South India. With Sediment-MP Isolation (SMI) unit, density separation was done with a hydrogen peroxide solution. Four forms of MPs namely, fragments, films, foams, and fibers with orange, white, green, and saffron red were observed. The plenitude and distribution of four forms of MPs and natural substrates were geometrically independent, with large amounts of microfragments within the research region accounting for 79.72% variation by Principal Component Analysis. FT-IR analyses of MPs showed the presence of polyamide, polyethylene, polyethylene glycol, polyethylene terephthalate, polypropylene, and polystyrene. Additionally, the scanning electron microscopic analysis revealed that the MPs have differential surface morphology with rough surfaces, porous structures, fissures, and severe damage. Most MPs comprised Si, Mg, Cu, and Al, according to energy dispersive X-ray analyses. The combined SMI, instrumental analyses and evaluation (heat map) of MPs in river sediments help assess contamination levels and types of MPs. The findings might provide an insight into the status of MPs in Kavery River sediments that could help in formulating regulations for MPs reduction and contamination in rivers eventually to protect the environment.

The micro-, submicron-, and nanoplastic hunt: A review of detection methods for plastic particles

Plastic particle pollution has been shown to be almost completely ubiquitous within our surrounding environment. This ubiquity in combination with a variety of unique properties (e.g. density, hydrophobicity, surface functionalization, particle shape and size, transition temperatures, and mechanical properties) and the ever-increasing levels of plastic production and use has begun to garner heightened levels of interest within the scientific community. However, as a result of these properties, plastic particles are often reported to be challenging to study in complex (i.e. real) environments. Therefore, this review aims to summarize research generated on multiple facets of the micro- and nanoplastics field; ranging from size and shape definitions to detection and characterization techniques to generating reference particles; in order to provide a more complete understanding of the current strategies for the analysis of plastic particles. This information is then used to provide generalized recommendations for researchers to consider as they attempt to study plastics in analytically complex environments; including method validation using reference particles obtained via the presented creation methods, encouraging efforts towards method standardization through the reporting of all technical details utilized in a study, and providing analytical pathway recommendations depending upon the exact knowledge desired and samples being studied.

Influence of surface oxidation on the quantification of polypropylene microplastics by pyrolysis gas chromatography mass spectrometry

The influence of photo-oxidation on the quantification of isotactic polypropylene by Pyrolysis Gas Chromatography/Mass Spectrometry (Pyr-GC/MS) was assessed. Beads (oval shape, ~5 mm) and fragments (irregular shaped, 250-50 μm and 500-1000 μm) were subjected to relatively harsh simulated accelerated weathering conditions (using a filtered xenon-arc reproducing sunlight's full spectrum) for up to 37 and 80 days, respectively. Samples collected (n = 10 replicates for each treatment) at increasing number of weathering days were analysed by Fourier-transform infrared spectroscopy with Attenuated Total Reflection (FTIR-ATR), scanning electron microscopy, and differential scanning calorimetry in order to assess the extent and the rate of degradation. The rate of surface oxidation occurred faster for fragments compared to beads, probably due to their higher surface area. Quantification of the polypropylene trimer (2,4-dimethyl-1-heptene) via double shot Pyr-GC/MS, showed that the signal of the trimer relative to the mass of polypropylene was reduced through weathering with a degradation rate of 1:3 faster for fragments over beads. Signal reduction and carbonyl index were correlated to show that polypropylene with a carbonyl index of ≥13 has a significantly reduced 2,4-dimethyl-1-heptene signal when compared to virgin material. Consequently, the quantification of polypropylene subjected to weathering under harsh conditions may be underestimated by 42% (fragments, carbonyl index: 18) to 49% (beads, carbonyl index: 30) when quantified by Pyr-GC/MS and using virgin polypropylene calibration standards. Pyrolysis at a lower temperature (350 °C) identified six degradation specific markers (oxidation products) that increased in concentration with weathering. Further comparisons between virgin and weathered microplastics may need to be considered to avoid underestimation of microplastic concentrations in future studies.

Searching Nanoplastics: From Sampling to Sample Processing

Nanoplastics (NPs) are considered emerging pollutants, namely unregulated contaminants whose toxic effect on humans and the environment has been demonstrated or suspected. They are the result of the physical fragmentation of the plastics that over time reach smaller dimensions (<100 nm). The issues related to the characterization and quantification of NPs in the environmental matrices are mainly related to the infinitepsimal size, to the fact that they are found in bulk, and to the different physico-chemical forms in which the same polymer can evolve over time by degradation. To deal with the study of a new class of pollutants it is necessary to assess the entire analytical method, carefully considering every single step (sampling, cleanup, qualitative, and quantitative analysis) starting from the validation method in the laboratory. This paper reviews the analytical method steps, focusing on the first ones, which the current literature often underestimates: laboratory tests, sampling, and sample processing; in fact, most errors and the quality of the analyses often depend on them. In addition, all newly introduced sample processing methods were examined.

Extraction of microplastics from sediment matrices: Experimental comparative analysis

Microplastics are small (<5 mm) fragments of plastic debris that are ubiquitous in oceans and terrestrial ecosystems. Studies on microplastics in sediment and soil matrices are particularly challenging because of the need to separate the plastics from the sediments. We investigated the efficiencies of 18 combinations of six extracting solutions (ESs) (oil, water, oil-in-water, NaCl, oil-in-NaCl, and NaI) and three isolation methods (IMs) (hand stirring, centrifugation, and aeration) for fine and coarse sediments, with low and high density polymers. IMs did not affect the extraction efficiency. Except in case of oil, all ESs enabled good extraction (84 ± 17%) of light polymers (PE and PE-ABS). NaI presented the best extraction efficiency (71 ± 17%) for the densest polymers (PET, PES, and PA). For these ESs, fibers were extracted at a lower efficiency than pellets and fragments, and sediment gran size did not affect the extraction. For other ESs, mean extraction rates ranged from 5% to 48%. Overall, the extraction efficiencies were lower than those found in the literature, despite repeating the separation process three times. The collection of floating materials remained a problem, as plastics tended to adhere to the glass wall. Our work will help the comparability between previous and future monitoring results and the selection of the most suitable protocols for future studies. This work clearly demonstrates also that there is no robust protocol for extracting all types and forms of microplastics from fine sediments and that research efforts to arrive at a reliable method remain by taking account the interaction of MPs with other particles as well as the electrostatic properties of MP.

New methodologies for the detection, identification, and quantification of microplastics and their environmental degradation by-products

Sampling, separation, detection, and characterization of microplastics (MPs) dispersed in natural water bodies and ecosystems is a challenging and critical issue for a better understanding of the hazards for the environment posed by such nearly ubiquitous and still largely unknown form of pollution. There is still the need for exhaustive, reliable, accurate, reasonably fast, and cost-efficient analytical protocols allowing the quantification not only of MPs but also of nanoplastics (NPs) and of the harmful molecular pollutants that may result from degrading plastics. Here a set of newly developed analytical protocols, integrated with specialized techniques such as pyrolysis-gas chromatography-mass spectrometry (Py-GC/MS), for the accurate and selective determination of the polymers most commonly found as MPs polluting marine and freshwater sediments are presented. In addition, the results of an investigation on the low molecular weight volatile organic compounds (VOCs) released upon photo-oxidative degradation of microplastics highlight the important role of photoinduced fragmentation at a molecular level both as a potential source of hazardous chemicals and as accelerators of the overall degradation of floating or stranded plastic debris.

Nylon 6 and nylon 6,6 micro- and nanoplastics: A first example of their accurate quantification, along with polyester (PET), in wastewater treatment plant sludges

A novel procedure for nylon 6 and nylon 6,6 polyamide (PAs) microplastics (MPs) quantification is described for the first time. The overall procedure, including quantification of poly(ethylene terephthalate) (PET), was tested on wastewater treatment plant (WWTP) sludges. The three polymers account for the largest global share of synthetic textile microfibers, being possibly the most common MPs released upon laundering in urban wastewaters. Therefore, measuring their content in WWTP sludges may provide an accurate picture of the potential risks associated with both the inflow of these MPs in natural water bodies and the practice of using WWTP sludges as agricultural soil amendment. The novel procedure involves PAs depolymerization by acid hydrolysis followed by derivatization of the monomers 6-aminohexanoic acid (AHA) and hexamethylene diamine (HMDA) with a fluorophore. Reversed-phase HPLC analysis with fluorescence detection results in high sensitivities for both AHA (LOD = 8.85·10^-4 mg/L, LOQ = 3.73·10^-3 mg/L) and HMDA (LOD = 2.12·10^-4, LOQ = 7.04·10^-4 mg/L). PET quantification involves depolymerization, in this case by alkaline hydrolysis, followed by HPLC analysis of its comonomer terephthalic acid. Eight sludge samples from four WWTPs in Italy showed contamination in the 29.3-215.3 ppm and 10.6-134.6 ppm range for nylon 6 and nylon 6,6, respectively, and in the 520-1470 ppm range for PET.

Polymer Identification and Specific Analysis (PISA) of Microplastic Total Mass in Sediments of the Protected Marine Area of the Meloria Shoals

Microplastics (MPs) quantification in benthic marine sediments is typically performed by time-consuming and moderately accurate mechanical separation and microscopy detection. In this paper, we describe the results of our innovative Polymer Identification and Specific Analysis (PISA) of microplastic total mass, previously tested on either less complex sandy beach sediment or less demanding (because of the high MPs content) wastewater treatment plant sludges, applied to the analysis of benthic sediments from a sublittoral area north-west of Leghorn (Tuscany, Italy). Samples were collected from two shallow sites characterized by coarse debris in a mixed seabed of Posidonia oceanica, and by a very fine silty-organogenic sediment, respectively. After sieving at <2 mm the sediment was sequentially extracted with selective organic solvents and the two polymer classes polystyrene (PS) and polyolefins (PE and PP) were quantified by pyrolysis-gas chromatography-mass spectrometry (Pyr-GC/MS). A contamination in the 8-65 ppm range by PS could be accurately detected. Acid hydrolysis on the extracted residue to achieve total depolymerization of all natural and synthetic polyamides, tagging of all aminated species in the hydrolysate with a fluorophore, and reversed-phase high performance liquid chromatography (HPLC) (RP-HPLC) analysis, allowed the quantification within the 137-1523 ppm range of the individual mass of contaminating nylon 6 and nylon 6,6, based on the detected amounts of the respective monomeric amines 6-aminohexanoic acid (AHA) and hexamethylenediamine (HMDA). Finally, alkaline hydrolysis of the residue from acid hydrolysis followed by RP-HPLC analysis of the purified hydrolysate showed contamination by polyethylene terephthalate (PET) in the 12.1-2.7 ppm range, based on the content of its comonomer, terephthalic acid.

Nanoplastics in aquatic systems - are they more hazardous than microplastics?

The fragmentation of plastic materials into nanoparticles of less than 1000 nm (secondary nanoplastics) and their possible accumulation in the environment is a recent matter of concern. There are still no suitable standard methods for determining the concentrations and chemical makeup of these particles in aquatic systems and the fate and effect of nanoplastics in the aquatic environment has been little explored, although there has been research using engineered nanoparticles as models. In this review, we give a summary of the (mainly laboratory-based) studies on the influences of nanoplastics. We aim to provide an updated overview of this emerging topic, reviewing the literature mainly from 2018 onwards and considering the effects of nanoplastics on ecosystems, their uptake and transport of polluting molecules, and the challenges that are faced by workers in this area. The review includes 119 references.

Microplastics Pollution as an Invisible Potential Threat to Food Safety and Security, Policy Challenges and the Way Forward

Technological advances, coupled with increasing demands by consumers, have led to a drastic increase in plastic production. After serving their purposes, these plastics reach our water bodies as their destination and become ingested by aquatic organisms. This ubiquitous phenomenon has exposed humans to microplastics mostly through the consumption of sea food. This has led the World Health Organization (WHO) to make an urgent call for the assessment of environmental pollution due to microplastics and its effect on human health. This review summarizes studies between 1999 and 2020 in relation to microplastics in aquatic ecosystems and human food products, their potential toxic effects as elicited in animal studies, and policies on their use and disposal. There is a paucity of information on the toxicity mechanisms of microplastics in animal studies, and despite their documented presence in food products, no policy has been in place so far, to monitor and regulates microplastics in commercial foods meant for human consumption. Although there are policies and regulations with respect to plastics, these are only in a few countries and in most instances are not fully implemented due to socioeconomic reasons, so they do not address the problem across the entire life cycle of plastics from production to disposal. More animal research to elucidate pathways and early biomarkers of microplastic toxicity that can easily be detected in humans is needed. This is to create awareness and influence policies that will address this neglected threat to food safety and security.

Hints at the Applicability of Microalgae and Cyanobacteria for the Biodegradation of Plastics

Massive plastic accumulation has been taking place across diverse landscapes since the 1950s, when large-scale plastic production started. Nowadays, societies struggle with continuously increasing concerns about the subsequent pollution and environmental stresses that have accompanied this plastic revolution. Degradation of used plastics is highly time-consuming and causes volumetric aggregation, mainly due to their high strength and bulky structure. The size of these agglomerations in marine and freshwater basins increases daily. Exposure to weather conditions and environmental microflora (e.g., bacteria and microalgae) can slowly corrode the plastic structure. As has been well documented in recent years, plastic fragments are widespread in marine basins and partially in main global rivers. These are potential sources of negative effects on global food chains. Cyanobacteria (e.g., Synechocystis sp. PCC 6803, and Synechococcus elongatus PCC 7942), which are photosynthetic microorganisms and were previously identified as blue-green algae, are currently under close attention for their abilities to capture solar energy and the greenhouse gas carbon dioxide for the production of high-value products. In the last few decades, these microorganisms have been exploited for different purposes (e.g., biofuels, antioxidants, fertilizers, and ‘superfood’ production). Microalgae (e.g., Chlamydomonas reinhardtii, and Phaeodactylum tricornutum) are also suitable for environmental and biotechnological applications based on the exploitation of solar light. Can photosynthetic bacteria and unicellular eukaryotic algae play a role for further scientific research in the bioremediation of plastics of different sizes present in water surfaces? In recent years, several studies have been targeting the utilization of microorganisms for plastic bioremediation. Among the different phyla, the employment of wild-type or engineered cyanobacteria may represent an interesting, environmentally friendly, and sustainable option.

Release of harmful volatile organic compounds (VOCs) from photo-degraded plastic debris: A neglected source of environmental pollution

Environmental pollution associated to plastic debris is gaining increasing relevance not only as a threat to ecosystems but also for its possible harmful effects on biota and human health. The release of toxic volatile organic compounds (VOCs) is a potential hazard associated with the environmental weathering of plastic debris. Artificial aging of reference polymers (polystyrene, polypropylene, polyethylene terephthalate, high and low density polyethylene) was performed in a Solar Box at 40 °C and 750 W/m². The volatile degradation products were determined before and after 1, 2, 3 and 4 weeks of aging using a validated analytical procedure combining headspace (HS) with needle trap microextraction (NTME) and gas chromatography/mass spectrometry (GC-MS). A progressive increase in VOCs was observed during artificial photo-degradation, whose chemical profile resulted polymer-dependent and included carbonyls, lactones, esters, acids, alcohols, ethers, aromatics. The amount of extractable fraction in polar solvents generally showed a similar trend. The same analytical procedure was used to determine VOCs released from plastic debris collected at a marine beach. All samples released harmful compounds (e.g. acrolein, benzene, propanal, methyl vinyl ketone, and methyl propenyl ketone), supporting the initial hypothesis that microplastics represent an unrecognized source of environmental pollution.