FTIR and Raman imaging for microplastics analysis: State of the art, challenges and prospects

Rapid detection and identification of plastic waste based on multi-wavelength laser Raman spectroscopy combining machine learning methods

Plastic waste has become a significant environmental concern, necessitating advancements in recycling efficiency.Enhancing the purity of recycled plastics facilitates the selection of suitable processing methods for different materials, thereby optimizing the recycling process.This study proposed a multi-wavelength laser Raman detection method and system to enable rapid and accurate identification of plastic waste.By analyzing the Raman spectra of various plastics under different laser wavelengths and introducing a fluorescence coefficient to quantify wavelength impact,the attribution of Raman characteristic peaks for distinct plastics has been elucidated, and the integrated area of Raman spectra across seven bands was identified as the key parameters for identifying plastics. By comparing neural networks, random forests, and k-nearest neighbor algorithms, it was determined that the k-nearest neighbor algorithm achieved the highest accuracy of 97.4 % and fastest identification speed of 1.2 ms/item when using integrated area of 7 characteristic bands as input. A plastic identification model incorporating data augmentation and k-nearest neighbors was finally developed and validated. A 100 % identification rate for actual waste plastic can be achieved by utilising a multi-wavelength laser Raman spectroscopy database. The results demonstrated that the multi-wavelength Raman system was highly effective for online or rapid recycling applications, enabling precise sorting of mixed plastic waste. This system significantly enhances the quality of recycled feedstock, contributing to the sustainability of plastic waste management.

Advancing pharmaceutical tablet analysis with laser direct infrared (LDIR) imaging

Laser direct infrared spectroscopy (LDIR) imaging is an emerging vibrational spectroscopic technique that enables rapid surface imaging by using reflectance spectra to capture critical physicochemical properties, such as chemical identity, particle size, shape, and distribution of components, within minutes or even seconds. Despite its advantages, LDIR imaging technology is still in its developmental stages, particularly in understanding method parameters such as the selection of wavenumber for peak and baseline points and the appropriate step size (pixels) for pharmaceutical analysis. In this study, in-house prepared and commercially available tablets were analyzed using LDIR imaging to assess the effects of method development options, particularly the relationship between step size and data acquisition time. Hyperspectral reflectance mode LDIR images were also collected and compared with those obtained from Raman microscopy to validate the accuracy of the LDIR images. The findings emphasize the need for careful wavenumber selection during method development. LDIR images for the evaluated tablets showed good agreement with Raman mapping and hyperspectral mode data sets, although the mean Feret diameter of particles was consistently smaller (14-40 % for active pharmaceutical ingredients (APIs) in the tested tablets) in the LDIR images. Overall, LDIR demonstrates strong potential as a valuable spectroscopic imaging technology for pharmaceutical applications.

A critical review on the migration, transformation, sampling, analysis and environmental effects of microplastics in the environment

As emerging pollutants, microplastics have recently received considerable attention owing to detection in various organisms and environments. Mass production and widespread use of plastic products increase their potential risks to humans owing to their persistent, mobile, and toxic properties. Numerous methods have been used to identify and quantify the various forms of microplastics, however, unified standards do not exist. In this review, we systematically summarize the sources, migration, transformation, and analytical methods for microplastics in diverse ecosystems, particularly the most recent sampling and identification techniques. Additionally, the environmental effects and health hazards of microplastics on aquatic and terrestrial systems, as well as human beings are discussed. We also present management strategies for reducing microplastics in a broader social and policy context. This review aims to provide an overview of the migration, transformation, sampling, analysis, and environmental effects of microplastics, which addresses knowledge gaps in microplastic pollution and provides proposals for key research gaps.

Distribution and characteristics of microplastics in fluvial sediments from the Koshi River Basin, Nepal

Microplastics (MPs) are emerging contaminants found in various ecosystems including oceans, lakes, rivers, sediment, air, and soil. Mapping of MPs in different deposition zones in fresh water sediment is important to identify their potential sources, sink, and transport mechanism. In this study, MPs were analyzed in sediment samples from Arun, Tamor, and Koshi Rivers in eastern Nepal. A total of 78 samples from 26 sites were collected from three independent deposition regions i.e., recent deposition (R0), recent past deposition (R1), and past deposition (R2) during monsoon season in 2023. All samples were analyzed following standard methods involving drying, peroxidation, density separation, microscopic examination and chemical identification by FTIR. In all the river basins differences in MPs count, color, and morphology were observed in three deposition regions. In Koshi basin the MPs count ranged from 7016-8876 MPKg-1, 8396-10596 MPKg-1, and 9416-9816 MPKg-1 in R2, R1 and R0 regions, respectively. The mean abundance was found to be higher in downstream especially in Koshi River. The predominant shapes, sizes, and colors found in all three river basins were fragment (52.5 %), 20-100 μm (58.86 %), and black (33.76 %). The particles were identified as polyamide, polypropylene, polyvinyl chloride, polysulfone, nylon, and polyether ether ketone. The pollution risk assessment indicated minimal MPs contamination upstream and moderate contamination downstream. Finally, principal component analysis (PCA) and land use and land cover change (LULC) data were utilized to identify the potential sources of MPs. Agricultural and anthropogenic sources were identified as major contributors to the MPs load. This study provides baseline data for MP concentrations and their potential sources in Arun, Tamor, and Koshi river sediments. These insights could be important for future MPs mitigation strategies.

A critical review of the ecotoxic effects of microplastics on aquatic, soil and atmospheric ecosystems and current research challenges

The extensive use of plastics has brought unparalleled convenience to human social development. However, this has also led to severe environmental and health challenges, with microplastic (MP) pollution emerging as one of the most pressing issues. As ubiquitous environmental pollutants, MPs persist in ecosystems and pose potential risks to both ecological and human health. Studies reveal that MPs impact aquatic, soil, and atmospheric ecosystems by altering their physicochemical properties and causing toxicological harm to resident organisms. Despite these findings, a comprehensive assessment and analysis of MP impacts, especially on atmospheric ecosystems, remains lacking. Similarly, the environmental biotoxicity mechanisms associated with MPs are yet to be systematically described. This review provides an in-depth discussion of the sources and characteristics of MPs, laying the background for elaborating their ecological effects. Current knowledge on MP ecotoxicity in aquatic, soil, and atmospheric ecosystems is then synthesized. Potential molecular mechanisms of biotoxicity are explored. Oxidative stress, inflammatory responses, and metabolic signaling pathway impairment are considered important pathways through which MPs induce toxic injury in environmental animals and have received widespread attention. Additionally, this review emphasizes the challenges faced in studying ecotoxic effects and mechanisms of MPs, such as the lack of reliable detection of environmental MPs and in-depth mining of relevant data, and suggests possible directions for future research. Although progress has been made, significant knowledge gaps remain. Addressing these gaps is critical if effective strategies are to be developed to reduce the environmental and health risks posed by MPs.

Machine Learning Advancements and Strategies in Microplastic and Nanoplastic Detection

Microplastics (MPs) and nanoplastics (NPs) present formidable global environmental challenges with serious risks to human health and ecosystem sustainability. Despite their significance, the accurate assessment of environmental MP and NP pollution remains hindered by limitations in existing detection technologies, such as low resolution, substantial data volumes, and prolonged imaging times. Machine learning (ML) provides a promising pathway to overcome these challenges by enabling efficient data processing and complex pattern recognition. This systematic Review aims to address these gaps by examining the role of ML techniques combined with spectroscopy in improving the detection and characterization of NPs. We focused on the application of ML and key tools in MP and NP detection, categorizing the literature into key aspects: (1) Developing tailored strategies for constructing ML models to optimize plastic detection while expanding monitoring capabilities. Emphasis is placed on harnessing the unique molecular fingerprinting capabilities offered by spectroscopy, including both infrared (IR) and Raman spectra. (2) Providing an in-depth analysis of the challenges and issues encountered by current ML approaches for NP detection. This Review highlights the critical role of ML in advancing environmental monitoring and improving our further, deeper investigation of the widespread presence of NPs. By identifying current key challenges, this Review provides valuable insights for future direction in environmental management and public health protection.

Fast Detection and Classification of Microplastics by a Wide-Field Fourier Transform Raman Microscope

A number of applications require methods to detect with high spatial resolution and chemical specificity microplastics (MPs) extracted from different matrices. Here we introduce a wide-field hyperspectral Fourier transform Raman microscope for the rapid detection and identification of MPs. The instrument, based on a common-path birefringent interferometer, combines high spatial (∼1 μm) and spectral (∼23 cm-1) resolution with fast measurement times (∼15 min for a 100 kpixel image) and enables the suppression of sample fluorescence by a proper choice of the scan interval of the interferometer. After validating the instrument on MPs of commercial origin, we demonstrate its ability to detect MPs extracted from different matrices, by filtering seawater and pretreated gastrointestinal tracts of fish, and analyzing the MPs concentrated onto the filters. We expect that our microscope will enable high-quality, cost-effective, and rapid identification of MPs, fulfilling also the requirements of large-scale monitoring plans of different environmental matrices.

Microplastic pollution in the glaciers, lakes, and rivers of the Hindu Kush Himalayas: Knowledge gaps and future perspectives

The Hindu Kush Himalayas (HKH), often referred to as the Third Pole and the Water Tower of Asia, represents a vital geo-ecological asset, providing essential services to millions of people. However, this once-pristine environment is increasingly threatened by the influx of microplastics. This study provides a comprehensive overview of the current state of microplastic pollution in the HKH region, identifies key research gaps, and highlights areas for future research. A review of existing literature reveals the lack of standardized protocols for microplastics analysis, which hinders cross-study comparisons. The reported microplastic abundances vary widely across environmental matrices including 0.14-31,200 MPs m-3 in river water, 0.072-26,000 MPs kg-1 in river sediments, 180-5500 MPs kg-1 in lake sediments, 55-2380 MPs kg-1 in lake shoreline sediments, 30-871.34 MPs L-1 in glaciers, and 2.23-130 MPs L-1 in lake surface water. Polymer characterization using spectroscopic techniques has identified 54 polymer types across different environmental matrices in the HKH region with polypropylene (PP) being the most dominant, followed by polyethylene (PE), and polystyrene (PS). The sources of microplastics in the HKH region include both local activities and long-range atmospheric transport. Although research on microplastics in the region has gained momentum in recent years, significant knowledge gaps remain regarding their fate, degradation mechanisms, and environmental impacts. Further studies are essential to investigate the role of microplastics as light-absorbing impurities that may accelerate glacier melting, as well as their implications for biodiversity and human health in the region.

Retention of microplastics in Halophila decipiens seagrass meadows

Microplastic (MP) trapping and storage by seagrasses and sediments highlight their role as potential long-term reservoirs for plastic particles. This study evaluated the presence of MPs in Halophila decipiens meadows and its associated sediments in two localities, Pichilingue and Los Aripes, in the southwest Gulf of California. At each locality, 12 samples were collected along two 30-m transects: six from vegetated and six from unvegetated sites. At Pichilingue, 93 items were found on H. decipiens, with a maximum of 46 items on roots, with films and fibers being the main MP forms and black the most frequent color. For sediments, an average of 231 ± 145 items kg-1 DW was estimated; the vegetated site showed 406 ± 184 items kg-1 DW, with black films (1016 items) as the most abundant items, while the unvegetated site showed 56 ± 11 items kg-1 DW, with transparent fragments (25 items) as the dominant items. The main MP type was polyethylene (38 items). At Los Aripes, MPs were not found on any structure of H. decipiens; but in sediments, the average was 17 ± 7 items kg-1 DW, with 13 ± 3 items kg-1 DW in the vegetated site and black and blue fibers (seven items each) as the dominant items, and 21 ± 10 items kg-1 DW in the unvegetated site and blue fibers (16 items) as the dominant items. The main MP type was polyethylene terephthalate. This research provides insight into the capacity of sediments and H. decipiens structures (leaves, petioles, rhizomes, and roots) to retain MPs derived from local human activities and the effect of environmental factors.

Persistence and Recovery of Polystyrene and Polymethyl Methacrylate Microplastic Toxicity on Diatoms

The increasing pollution of polystyrene (PS) and polymethyl methacrylate (PMMA) microplastics (MPs) has become a global marine environmental problem. Diatoms contribute nearly 40% of marine primary productivity and shape the nitrogen cycle in the oceans. However, the persistence of the phytotoxicity of MPs on diatoms, especially nitrogen assimilation, remains largely unknown. To examine the persistence of PS and PMMA toxicity in diatoms, two subexperiments (a 96 h exposure followed by a recovery phase) were conducted on Thalassiosira pseudonana at concentrations ranging from 0.001 to 1 mg/L. The results showed that PS and PMMA inhibited algal growth by 3.76-6.49% and 4.44-8.37%; increased oxidative stress by 10.06-30.51% and 30.46-38.12%; and caused ultrastructural damage by 14.24-25.56% and 12.28-20%, respectively, consistent with the downregulation of glyoxylate, dicarboxylate metabolism, and glutathione metabolism. At the recovery stage, the algal density induced by PS was significantly recoverable at 0.001 and 0.01 mg/L, consistent with the enhanced carbohydrate metabolisms. After recovery, the cell permeability and reactive oxygen species (ROS) levels induced by PS and PMMA were significantly decreased at 1 mg/L, respectively, which was closely related to the downregulation of glycine, serine, and threonine metabolism and the upregulation of pantothenate and coenzyme A biosynthesis. Moreover, the inhibition of nitrogen assimilation enzymic activities induced by PS and PMMA was significantly recovered at 1 mg/L despite the downregulation of nitrogen metabolism. This study highlights the phenomena and mechanisms of phytotoxicity and recovery, and provides new insights for comprehensive understanding and evaluation of environmental risks of MPs.

Microplastic contamination in sediments: Analytical techniques and case-based evaluations

Microplastics (MPs) pollution in sediments has gained critical attention due to its pervasive presence and potential ecological risks. This review synthesizes the latest advancements in analytical techniques, providing a comprehensive overview of separation and identification methods tailored to complex sedimentary matrices. Density-based approaches, such as ZnCl2 or NaI solutions, and enzymatic digestions are increasingly refined to isolate MPs of varying sizes, yet discrepancies in mesh sizes, reagent concentrations, and digestion protocols continue to complicate cross-study comparisons. Meanwhile, cutting-edge spectroscopic tools-μFTIR, Raman imaging, thermal analyses-have greatly enhanced polymer identification down to the tens-of-micrometers scale. Case studies spanning urban estuaries to remote deep-sea basins underscore the pervasive nature of MPs worldwide, with fibers and fragments frequently dominating sediment samples. Factors such as polymer density, hydrodynamics, and biofouling contribute to the diverse distribution patterns, revealing that even ostensibly pristine environments are not exempt from contamination. Although the precise ecological and toxicological consequences of long-term sediment-bound MPs remain partly unclear, growing evidence points to intricate interactions with co-occurring contaminants and potential trophic transfer. To address these knowledge gaps, this review emphasizes the urgent need for methodological standardization and collaborative initiatives, particularly for emerging challenges like nanoplastic detection. By integrating robust sampling approaches, advanced analytical tools, and interdisciplinary research, scientists and policymakers can more accurately map and mitigate the impacts of sediment-associated MPs on aquatic ecosystems.

Automated Machine-Learning-Driven Analysis of Microplastics by TGA-FTIR for Enhanced Identification and Quantification

Microplastics persist as ubiquitous environmental contaminants, and efficient methods to quantify and identify their presence are essential for assessing their environmental and health impacts. Common identification approaches typically fall under either vibrational spectroscopy or thermoanalytical techniques with thermogravimetric analysis (TGA) coupled with Fourier transform infrared (FTIR) spectroscopy bridging the intersection. Despite its potential, TGA-FTIR remains relatively underutilized for microplastic analysis, even though each thermogram is associated with approximately 200 FTIR spectra that can be rapidly assessed with targeted automated data analysis. This work explores the development of data analysis routines specialized in identifying plastic components from TGA-FTIR. A dedicated spectral library and a matching algorithm were created to identify polymers from their gas-phase FTIR spectra. The approach was further enhanced by utilizing machine learning (ML) classification techniques, including k-nearest neighbor, random forest, support vector classifier, and multilayer perceptron. The performance of these classifiers for complex data sets was evaluated using synthetic data sets generated from the spectral library. ML techniques offered precise and unambiguous identification compared with a custom spectral matching algorithm. By correlating polymer identities with mass loss in the thermogram, this approach combines qualitative insights with semiquantitative analysis, enabling a streamlined assessment of plastic content in samples.

Unraveling microplastic behavior in simulated digestion: Methods, insights, and standardization

Despite the rapid expansion of in vitro digestion studies on microplastics (MPs), the field remains fragmented due to inconsistent methodologies, varying analytical approaches, and a lack of standardized protocols. These discrepancies hinder cross-study comparisons, complicate risk assessments, and limit the applicability of in vitro models for understanding MP fate and pollutant interactions in the gastrointestinal environment. A comprehensive synthesis is needed to assess progress, identify research gaps, and establish a unified research direction. This review systematically evaluates 85 studies (2020-2024), consolidating key findings and methodological challenges. It examines disparities in digestion protocols, fluid compositions, and exposure conditions, assessing how factors such as pH, enzyme activity, residence time, and temperature shape MPs' behavior and physicochemical transformations. Key findings on bio-corona formation, structural modifications, contaminant bioaccessibility, and interactions with digestive enzymes are synthesized to provide a clearer picture of MP behavior during digestion. With the field remains dominated by studies on polystyrene and polyethylene MPs in human-based models, inconsistencies persist, highlighting the urgent need for standardized methodologies. By addressing these gaps, this review lays a critical foundation for improving reproducibility, advancing standardization efforts, and strengthening exposure assessments, ultimately enhancing our understanding of MP ingestion risks to human health.

Machine learning-integrated droplet microfluidic system for accurate quantification and classification of microplastics

Microplastic (MP) pollution poses serious environmental and public health concerns, requiring efficient detection methods. Conventional techniques have the limitations of labor-intensive workflows and complex instrumentation, hindering rapid on-site field analysis. Here, we present the Machine learning (ML)-Integrated Droplet-based REal-time Analysis of MP (MiDREAM) system. Utilizing a compact peristaltic pump, the system achieved high-throughput droplet generation (> 200 Hz) while encapsulating MPs in uniform droplets (142 ± 8 μm). A high-resolution complementary metal oxide semiconductor (CMOS) sensor combined with an optimized YOLO v8 ML model was employed for real-time analysis, achieving a mean average precision (mAP) of 0.982 and an area under the curve (AUC) of 97.64 %. Comparative analysis with hemocytometer counting and surface-enhanced Raman spectroscopy (SERS) demonstrated the superior performance of the system, demonstrating high correlation (R² = 0.9965) and minimal deviation (6.36 %) from theoretical values. The system accurately classified MPs of different sizes, achieving accuracies of 95.4 %, 87.9 %, 95.3 %, 85.3 %, and 92.5 % for 3, 5, 10, 30, and 50 μm particles, respectively. Validation with real-world water samples confirmed the system adaptability, while maintaining high detection accuracy (> 90 %). The on-site field tests of MiDREAM system also demonstrated its robust performance for environmental monitoring in a variety of environments. Therefore, our portable and integrated MiDREAM system offers a promising solution for real-time environmental monitoring applications.

Review of Techniques for the Detection, Removal, and Transformation of Environmental Microplastics and Nanoplastics

Plastic residues have emerged as a significant challenge in the environmental sector. Microplastics, which are plastic fragments smaller than 5 mm, have the ability to disperse through the atmosphere, oceans, and land, posing a serious threat to human health by accumulating in the food chain. However, their minuscule size makes it difficult to effectively remove them from the environment using the current technologies. This work provides a comprehensive overview of recent advancements in microplastic detection and removal technologies. For detection methods, we discuss commonly used techniques such as microscopic analysis, thermal analysis, mass spectrometry, spectroscopic analysis, and energy spectrometry. We also emphasize the importance of integrating various analytical and data-processing techniques to achieve efficient and nondestructive detection of microplastics. In terms of removal strategies, we explored innovative methods and technologies for extracting microplastics from the environment. These include physical techniques like filtration, adsorption, and magnetic separation; chemical techniques such as coagulation-flocculation-sedimentation and photocatalytic conversion; and bioseparation methods such as activated sludge and biodegradation. We also highlight the promising potential for converting microplastic contaminants into high-value chemicals. Additionally, we identify current technical challenges and suggest future research directions for the detection and removal of microplastics. We advocate for the development of unified and standardized analytical methods to guide further research on the removal and transformation of microplastics.

Microplastic Passage through the Fish and Crayfish Digestive Tract Alters Particle Surface Properties

Most studies on the effects of organisms on microplastic characteristics have focused on microorganisms, while the impact of animal feeding behavior, particularly in aquatic species like fish and decapod crustaceans, has been less explored. This study examines how polyethylene spherical microplastics (275 μm in diameter) passing through the digestive tracts of crucian carp (Carassius carassius) and Australian crayfish (Cherax quadricarinatus) affect surface properties, particle size, and bacterial colonization. The species were fed diets with or without microplastics. The particles underwent two rounds of passage through the digestive tracts and were then exposed to known bacterial densities. Surface damage, size, and biofilm coverage were analyzed using scanning electron microscopy, while alterations in surface chemical composition were assessed through Fourier transform infrared spectroscopy with attenuated total reflectance, and the formation and penetration of nanoplastics in gut tissues and glands were determined using Py-GC/MS. Results show that the passage significantly altered surface properties and reduced microplastic size, without affecting chemical composition or nanoplastic penetration into tissues. These changes promoted bacterial colonization compared to controls. The findings suggest that animal feeding activity may play an important role in the mechanical fragmentation of microplastics in aquatic environments, potentially leading to their faster degradation.

Two sides of the same coin: Weathering differences of plastic fragments in coastal environments around the globe

Plastic debris in coastal environments usually undergoes weathering due to various environmental conditions. However, the weathering effects on exposed and shaded sides of the same plastics are underexplored. In this study, 1573 plastic fragments were collected from 15 coastal sites worldwide between December 2021 and December 2022, and weathering experiments were conducted outdoors. The field investigation showed significant two-sided weathering differences of plastic fragments. The weathering morphology included biota, cracks, delamination, discoloration, etc. The weathering degree was assessed with three metrics, i.e., line density (0-58 mm/mm2), surface loss (0-92 %), and texture index (0-2). The 3D magnitudes of these three metrics revealed the two-sided weathering differences of plastic fragments. Specifically, 43 % of the samples had magnitudes > 5, indicating significant differences. Outdoor simulations suggested that sun-exposed sides developed more cracks, pores, and bubbles, while shaded sides remained smoother. After 12 months, the line density increased from 2.85 to 9.23 mm/mm² for polyethylene (PE) and 4.16-8.47 mm/mm² for polypropylene (PP) (p < 0.05). The carbonyl index increased from 0.50 to 1.70 (PE), from 0.18 to 1.10 (PP), and from 0.45 to 1.57 (polyvinyl chloride). This increase indicated oxidative degradation on sun-exposed sides. Our results highlighted the uneven degree of weathering on both sides of the same plastic fragment due to different environmental factors. The study provided critical insights for creating more accurate models to predict plastic degradation, which will help inform global strategies to reduce plastic pollution.

Advancements and challenges in microplastic detection and risk assessment: Integrating AI and standardized methods

Microplastics (MPs) pose significant threats to ecosystems and human health due to their persistence and widespread distribution. This paper provides a comprehensive review of sampling methods for MPs in aquatic environments, soils, and biological samples, assessing pre-treatment procedures like digestion and separation. It examines the application and limitations of identification techniques, including microscopic observation, spectroscopic analysis, and thermal analysis. The review highlights the potential of AI technology to enhance detection efficiency and precision. It underscores the necessity of standardized protocols for consistent sampling and detection, and the importance of systematic risk assessment methodologies for managing environmental and health risks associated with MPs. The paper concludes with recommendations for future research, emphasizing the standardization of methods, advancement of detection technologies, integration of AI, and comprehensive health risk assessments. This review will be helpful for researchers to comprehensively understand the current main detection technologies and risk assessment methods of the MP, and to accelerate the establishment of an artificial intelligence regulatory framework for MPs.

μ-FTIR Reflectance Spectroscopy Coupled with Multivariate Analysis: A Rapid and Robust Method for Identifying the Extent of Photodegradation on Microplastics

Understanding the origins of microplastics (MPs) and evaluating the consequences of plastic pollution require precise chemical information. Moreover, MPs undergo chemical changes due to photoaging, which are worth investigating since they can influence the effects of MPs on living beings and the environment. Micro-Fourier-transform infrared (μ-FTIR) spectroscopy is a key technique for screening MPs, combining optical imaging with chemical information from IR spectra. While reflectance μ-FTIR spectroscopy's sensitivity to particle thickness and photodegradation complicates automated spectral matching, it can provide valuable information if coupled with multivariate analysis of the data. This study developed a robust method for identifying MPs, even when they are modified by photodegradation. Various acquisition methods (ATR-IR and μ-transflectance-IR), data pretreatments, and data set analysis procedures were examined, and critical aspects were addressed. The proposed method, using μ-TR-IR and principal component analysis (PCA), proved effective for classifying MPs and analyzing their degradation, offering increased sensitivity and a faster workflow compared with manual spectral comparison. μ-TR-IR showed earlier changes in relevant bands, indicating higher sensitivity to degradation than ATR-IR spectroscopy. Despite the notorious issue of spectral artifacts, our results suggest that valuable information can be collected without using sophisticated preprocessing techniques. On the contrary, the presence of the artifacts allows extracting some information on the particles' thickness. Finally, PCA results were successfully validated for the polymer classification reliability by a test set and compared with the carboxyl index (CI) method to validate the ability to assess degradation. While CI is the most diffused parameter to assess polymer degradation, PCA, which considers the entire spectrum and does not rely on manual integration of single peaks, is inherently more robust than CI and can take into account multiple degradation mechanisms.

Screening for microplastics in agricultural soils: Applying green chemistry principles in extraction and analysis

In recent years, microplastic (MP) pollution has garnered significant attention owing to its ability to permeate various ecosystems, including soil. These particles can infiltrate the environment, either directly or through the degradation of larger plastic items. Despite growing concerns, standardized methods for quantification are still lacking. This study aimed to screen for the presence of MPs in agricultural soils while incorporating green analytical principles in the methodology. A density separation followed by centrifugation was employed, based on the principles of the QuEChERS extraction method. This approach minimized sample quantities, reagent consumption, and waste production, ensuring efficient extraction and analysis. Recovery tests using certified soils spiked with pristine MPs, specifically polystyrene, polypropylene (PP), and ethylene-vinyl acetate for larger MPs (3-5 mm), and low-density polyethylene, polyamide 6, and tire wear particles for smaller MPs (15-300 μm), achieved recovery levels exceeding 69% for smaller MPs and over 91% for larger particles. Spectroscopic analysis revealed slight alterations in the Raman spectra of MPs after extraction. Transitioning to agricultural soil analysis has revealed challenges, including spectral interferences. Nine mesoplastics (5-20 mm) were detected, predominantly consisting of PP and polyethylene (PE), along with seven MPs, three of which were individually identified as PE-based, while the remainder were inconclusive, including one fiber. The evaluation of the method's sustainability using the Analytical Eco-Scale and Analytical Greenness Calculator Metric (AGREE), with scores of 82 out of 100 and 0.66 out of 1, respectively, demonstrated its potential as a reliable approach to MP analysis in soils. This study highlights the potential of integrating green analytical chemistry principles into MP extraction methodologies and emphasizes the value of the proposed QuEChERs-based approach for improving the sustainability and efficiency of MP monitoring in agricultural soils.

A critical review of microplastics characterisation in aquatic environments: recent trends in the last 10 years

Anthropogenic activities have introduced various contaminants into freshwater and marine ecosystems. Microplastics (MPs) are persistent and ubiquitous contaminants threatening natural ecosystems and impairing organisms at different biological levels of organization. Their durability and degradation rate pose a great concern in the scientific community, and thus, several techniques have been used to detect MPs effectively. The present study critically reviews the most commonly used techniques (FTIR, Raman, and fluorescence) and others considered novel regarding MP detection and characterisation, namely LIBS. Despite the effectiveness of such methodologies, none are free from drawbacks. The scientific community must join efforts to create, for example, innovative real-time (bio)sensing methodologies for MPs to overcome this gap.

Spider Webs as Passive Monitors of Microplastic and Its Copollutants in Indoor Environments

Indoor environments are particularly vulnerable to microplastics (MPs) and associated copollutants due to limited air circulation and particulate matter accumulation. Continuous monitoring is essential to evaluate exposure levels and health risks. We propose using indoor spider webs as passive monitors for MPs and their copollutants. MPs were found in both web and dust samples with nonuniform distribution (p < 0.05), indicating contamination hotspots. Web samples had significantly higher MP levels (138-33,570 MPs/g) compared to dust samples (59-9324 MPs/g). A strong positive correlation (r = 0.93, p < 0.05) between MPs in dust and webs suggests that spider webs are effective bioindicators of indoor MP contamination. The study also revealed the presence of Bisphenol A and various phthalic acid esters (PAEs). Co-pollutant concentrations ranged from 52.02-1971.78 μg/kg in webs and 43.18-518.42 μg/kg in dust. Diethyl phthalate (DEP) was more common in webs, while Dibutyl phthalate (DBP) predominated in dust. These findings highlight spider webs' potential as both effective biomonitoring tools and significant sinks for MPs and their cocontaminants in indoor environments.

Feasibility study on non-destructive detection of microplastic content in flour based on portable Raman spectroscopy system combined with mixed variable selection method

Microplastics, as emerging environmental pollutants, have garnered considerable attention due to their contamination of both the environment and food. Microplastics can infiltrate the human food chain through multiple pathways, potentially posing health risks to humans. Currently, non-destructive testing of microplastics in food is considered challenging. This study aims to investigate the feasibility of employing a portable Raman spectroscopy system for non-destructive detection of microplastic content (polystyrene, PS; polyethylene, PE) in flour. In this study, a portable spectrometer was used to collect flour spectra of different abundances of microplastics. To enhance the predictive performance of the partial least squares (PLS) model, a mixed variable selection strategy that combined the wavelength interval selection method (Synergy interval partial least squares, siPLS) and the wavelength point selection method (Least absolute shrinkage and selection operator, LASSO; Multiple feature-spaces ensemble by least absolute shrinkage and selection operator, MFE-LASSO) was proposed. Four regression models (PLS, siPLS, siPLS-LASSO, siPLS-MFE-LASSO) were developed and compared for detecting PS and PE content in flour. The siPLS-MFE-LASSO model exhibited the best generalization performance in the prediction set, and was considered to have the best generalization performance (PS: RP2 = 0.9889, RMSEP=0.0344 %; PE: RP2 = 0.9878, RMSEP=0.0361 %). In conclusion, this study has demonstrated the potential of using a portable Raman spectrometer in conjunction with a mixed variable selection algorithm for non-destructive detection of PS and PE content in flour, providing more possibilities for non-destructive detection of microplastic content in food.

Spatial patterns of microplastics in freshwater bivalves (Bivalvia: Unionidae and Sphaeriidae) relative to municipal wastewater effluent discharges

Microplastics are discharged by municipal wastewater treatment plants (WWTPs); however, their uptake by filter-feeding freshwater bivalves is poorly understood. This study examined the abundance and characteristics of microplastics in wild bivalves from five locations along a 155 km stretch of the Grand River (Ontario, Canada) in 2021-2022, including upstream and downstream of three municipal WWTPs. At each site, fingernail clams (Sphaeriidae spp., n = 5 composites), freshwater mussels (Lasmigona costata, n = 10; gill, digestive gland, and hemolymph), and surface water (n = 3) were sampled at a single timepoint. Microplastics (particles >38 μm to 5 mm) were isolated and visualized via stereomicroscopy, and a subset chemically analyzed using Fourier transform infrared spectroscopy. Fingernail clams contained the highest total blank corrected microparticle counts (35.5 ± 29.4 g-1 [mean ± SD]), mussel tissues ranged from 4.3 ± 4.2 mL-1 in hemolymph to 6.5 ± 8.1 g-1 in digestive gland, and water contained 5.5 ± 2.8 L-1. Fibers were the dominant morphology across all samples, most particles were between 80 μm and 2 mm in length and, of those analyzed chemically, 30.0% were a plastic polymer. At sites downstream of WWTP outfalls, elevated counts were only seen in mussel gills and not in other bivalve tissues or water compared with upstream samples. Although microplastics were found across all sites in both biotic and abiotic compartments, results suggest little impact of WWTP discharges on their uptake in downstream bivalves.

Plastic input and dynamics in industrial composting

Green and biowaste, processed within large facilities into compost, is a key fertilizer for agricultural and horticultural soils. However, due to improper waste disposal of plastic, its residues often remain or even lead to the formation ofmicroplastics (1 µm - 5 mm, MiPs) in the final compost product. To better understand the processes, we first quantified 'macroplastics' (> 20 mm, MaPs) input via biowaste collection into an industrial composting plant, and, then determined MiP concentrations at five stages during the composting process (before and after shredding and screening processes), and in the water used for irrigation. The total concentrations of MaPs in the biowaste collected from four different German districts ranged from 0.36 to 1.95 kg ton-1 biowaste, with polyethylene (PE) and polypropylene (PP) representing the most abundant types. The "non-foil" and "foil" plastics occurred in similar amounts (0.51 ± 0.1 kg ton-1 biowaste), with an average load of 0.08 ± 0.01 items kg-1 and 0.05 ± 0.01 items kg-1, respectively. Only 0.3 ± 0.1 kg MaP t-1 biowaste was biodegradable plastic. Compost treatment by shredding tripled the total number of MaPs and MiPs to 33 items kg-1, indicating an enrichment of particles during the process and potential fragmentation. Noticeably, a substantial amount of small MiPs (up to 22,714 ± 2,975 particles L-1) were found in the rainwater used for compost moistening, being thus an additional, generally overlooked plastic source for compost. Our results highlight that reducing plastic input via biowaste is key for minimizing MiP contamination of compost.

Microplastics in aquatic ecosystems: Detection, source tracing, and sustainable management strategies

Microplastics (MPs) are emerging contaminants characterized by persistence, cross-media transport, and complex pollutant interactions, posing serious ecotoxicological risks to ecosystems and human health. Effective MPs management requires multi-faced, long-term, strategies involving targeted sampling, quantitative detection, and comprehensive risk assessments, all of which entail significant resource investment. Despite advancements in remediation technologies, a holistic governance framework integrating these innovations remains underdeveloped. This review synthesizes current knowledge on MPs, elaborating on their diverse morphologies, degradation pathways, and their role as vectors for toxic substances. State-of-the-art extraction techniques are evaluated in this article, including micropore adsorption using nanocomposites, alongside the incorporation of advanced analytical tools such as spectroscopic methods, electron microscopy, and bioinformatics to augment environmental forensics. This review also underscores the necessity of formulating robust global policies to regulate MPs pollution and discusses the potential of biodegradation and thermal degradation as sustainable solutions for MPs removal. By promoting an interdisciplinary approach, this review advocates for a coordinated global response, integrating environmental science, policy frameworks, and waste management strategies to mitigate the escalating impact of MPs on ecosystems and human well-being.

Novel calibration approach for particle size analysis of microplastics by laser ablation single particle-ICP-MS

The need to analyze and characterize microplastics (MPs) is ever-increasing to monitor and understand their environmental impact. In this work, a developed calibration approach that utilizes an in-house-created polystyrene (PS) thin film for the sizing of MPs is presented, circumventing the need for certified particulate standard material. LA was used for sampling and transporting intact MPs of different sizes and polymer types to the ICP-MS. For the calibration, defined amounts of carbon were introduced into the ICP-MS by quantitatively ablating a polymer thin film with different laser spot sizes. With this approach, a LOD of 4.85 pg carbon was obtained, which translates to a size of 2.12 μm for spheric PS particles. The calibration using PS thin film was successfully applied to sampled PS MPs and allowed accurate sizing of 2 μm, 3 μm, and 4.5 μm particles. When using the PS calibration for determining polyvinyl chloride (PVC) and poly(methyl methacrylate) (PMMA) particle sizes, a good estimate of the size could be achieved despite the different compositions of the polymers. This indicates the universal applicability of the presented approach. The investigation of the transport efficiency showed that it is mainly influenced by particle size, and factors such as the polymer type and length of the transport line and carrier gas. Under optimum conditions, up to 95% of the sampled particles were detected.

Exploring Innovative Approaches for the Analysis of Micro- and Nanoplastics: Breakthroughs in (Bio)Sensing Techniques

Plastic pollution, particularly from microplastics (MPs) and nanoplastics (NPs), has become a critical environmental and health concern due to their widespread distribution, persistence, and potential toxicity. MPs and NPs originate from primary sources, such as cosmetic microspheres or synthetic fibers, and secondary fragmentation of larger plastics through environmental degradation. These particles, typically less than 5 mm, are found globally, from deep seabeds to human tissues, and are known to adsorb and release harmful pollutants, exacerbating ecological and health risks. Effective detection and quantification of MPs and NPs are essential for understanding and mitigating their impacts. Current analytical methods include physical and chemical techniques. Physical methods, such as optical and electron microscopy, provide morphological details but often lack specificity and are time-intensive. Chemical analyses, such as Fourier transform infrared (FTIR) and Raman spectroscopy, offer molecular specificity but face challenges with smaller particle sizes and complex matrices. Thermal analytical methods, including pyrolysis gas chromatography-mass spectrometry (Py-GC-MS), provide compositional insights but are destructive and limited in morphological analysis. Emerging (bio)sensing technologies show promise in addressing these challenges. Electrochemical biosensors offer cost-effective, portable, and sensitive platforms, leveraging principles such as voltammetry and impedance to detect MPs and their adsorbed pollutants. Plasmonic techniques, including surface plasmon resonance (SPR) and surface-enhanced Raman spectroscopy (SERS), provide high sensitivity and specificity through nanostructure-enhanced detection. Fluorescent biosensors utilizing microbial or enzymatic elements enable the real-time monitoring of plastic degradation products, such as terephthalic acid from polyethylene terephthalate (PET). Advancements in these innovative approaches pave the way for more accurate, scalable, and environmentally compatible detection solutions, contributing to improved monitoring and remediation strategies. This review highlights the potential of biosensors as advanced analytical methods, including a section on prospects that address the challenges that could lead to significant advancements in environmental monitoring, highlighting the necessity of testing the new sensing developments under real conditions (composition/matrix of the samples), which are often overlooked, as well as the study of peptides as a novel recognition element in microplastic sensing.

Control of Nanoparticle Size of Intrinsically Fluorescent PET (Polyethylene Terephthalate) Particles Produced Through Nanoprecipitation

Plastics are widely produced due to their stability and ease of manufacturing, but many of them quickly become a waste, breaking down into microplastics and nanoplastics. While methods for the identification and characterization of plastic particles are well consolidated, the small size of nanoplastics presents challenges for their detection and analysis. Furthermore, due to the difficulty of identifying nanoplastics, analytical studies concerning their effect on cells and a comprehensive spectroscopic characterization are still lacking. In this paper, we overcome this obstacle by synthesizing and characterizing, for the first time, PET nanoparticles with specific, stable dimensions through a top-down approach. Using hexafluoroisopropanol-chloroform as a solvent, we prepared PET solutions at various concentrations and analyzed their spectral properties over time. Our results show that PET aggregates into nanoparticles, the quantity of which increases with concentration. These findings provide crucial insights for the detection of nanoplastics in environmental samples through fluorescence measurements and can potentially be used to produce stable PET nanoparticles to evaluate their cytotoxicity.

Advancements in Assays for Micro- and Nanoplastic Detection: Paving the Way for Biomonitoring and Exposomics Studies

Although plastic pollution and exposure to plastic-related compounds have received worldwide attention, health risks associated with micro- and nanoplastics (MNPs) are largely unknown. Emerging evidence suggests MNPs are present in human biofluids and tissue, including blood, breast milk, stool, lung tissue, and placenta; however, exposure assessment is limited and the extent of human exposure to MNPs is not well known. While there is a critical need to establish robust and scalable biomonitoring strategies to assess human exposure to MNPs and plastic-related chemicals, over 10,000 chemicals have been linked to plastic manufacturing with no existing standardized approaches to account for even a fraction of these exposures. This review provides an overview of the status of methods for measuring MNPs and associated plastic-related chemicals in humans, with a focus on approaches that could be adapted for population-wide biomonitoring and integration with biological response measures to develop hypotheses on potential health effects of plastic exposures. We also examine the exposure risks associated with the widespread use of chemical additives in plastics. Despite advancements in analytical techniques, there remains a pressing need for standardized measurement protocols and untargeted, high-throughput analysis methods to enable comprehensive MNP biomonitoring to identify key MNP exposures in human populations. This review aims to merge insights into the toxicological effects of MNPs and plastic additives with an evaluation of analytical challenges, advocating for enhanced research methods to fully assess, understand, and mitigate the public health implications of MNPs.

Oxidative purification of microplastics in riverine suspended matter samples - Solving the challenge of plant debris removal for microplastic analysis

Riverine suspended matter (river-SPM) contains large amounts of natural particles consisting of cellulose and lignin, posing a challenge for microplastic (MPs) analysis. Additionally, organic matter composition under seasonal and discharge-related dynamics varies for each river. Therefore, this study attempted to identify a universally applicable clean-up procedure to remove matrix particles with high organic matter content, mainly plant debris, from the river-SPM samples. This study tested six digestion procedures adapted from existing (ligno)cellulosic digestion/oxidation methods with a river-SPM sample followed by density separation using sodium polytungstate. From these, NaOCl treatment (CL) showed the highest efficiency of organic matter removal, eliminating 96-100 % of the matrix weight. Exposure of tested MPs (in size range of 100-500 μm) in the CL protocol showed no adverse effect on polypropylene (PP), polyethylene (PE), polystyrene (PS), and polyethylene terephthalate (PET). Similarly, no detrimental matrix effects were found on 100 μm spherical PS standard particles spiked in the river-SPM. This procedure achieved high recovery rates of tested plastics (92-100 %). In terms of method applicability, the procedure was successfully applied to samples from different seasons containing various matrix concentrations and compositions. Although samples with high amounts of plant debris needed to undergo this procedure twice, only minor alteration of the particle surface and IR spectrum of PS presented and no adverse effect on PP. To further tackle the high and varied concentration of plant-derived matrix in river-SPM samples, a novel sequential oxidation protocol (2DOCL) combining cellulose dissolution, Fenton's oxidation, and NaOCl oxidation was developed, resulting in a more (time) effective and predictable process, demonstrating no severely destructive effect on tested plastics. The sequential digestion protocol can be optimized for certain matrices as applying all steps will not be necessary.

Challenges in Raman spectroscopy of (micro)Plastics: The interfering role of colourants

Rising plastic consumption leads to widespread microplastic (MP) contamination. Raman spectroscopy is widely used for MP identification due to its ability to analyse particles as small as 1 μm. However, it faces challenges such as interference from pigments and additives. In this study, we aim to assess the accuracy of Raman micro-spectroscopy in identifying coloured plastic samples by applying various oxidative treatments to eliminate the possible interference effect caused by colourants associated with the sample. Standard and coloured microplastics were analysed using a Raman imaging microscope. Coloured plastics were treated with H2O2 30%, Sodium hypochlorite 5%, and Fenton reagent (H2O2 30% and Ferrous sulphate 0.2 M) for 24, 48, and 72 h. The Raman spectra were acquired after treatment to assess the impact of the treatment procedure on the polymer identification. Our results revealed that colourants significantly impact Raman spectra by peak broadening and/or fluorescence effects, which reduces identification accuracy and match scores Red pigments particularly obscure polymer identification. Treatments like oxidation and Fenton's reagent showed limited effectiveness. Additives in plastic samples can affect the accuracy of polymer identification by the Raman spectroscopy technique. Common treatment procedures do not improve the accuracy of identification. In order to improve the reliability of Raman analysis, essential factors such as utilizing multiple excitation lasers and appropriate CCD detectors, establishing a comprehensive reference library of colourants and additives, and employing advanced techniques like time-gated Raman spectroscopy or Surface-Enhanced Raman Spectroscopy (SERS) should be considered.

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

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

Electrophoresis and Quartz Crystal Microbalance Instrumentation to Sense Nanoplastics in Water

We report a Technical Note on detecting nanoplastics in water samples through electrophoresis and quartz crystal microbalance (QCM) instrumentation. We conducted electrophoresis experiments by immersing a QCM in a sample of ultrapure water containing polyethylene (PE) nanoplastics. It was interesting to observe that nanoplastics were attracted toward the QCM and adhered to one side of the QCM electrode. The attached particles introduced mass loading to the QCM and were characterized by a decrease in resonance frequency of the crystal. Furthermore, when a small region around the center of electrode was alone exposed for direct contact in water and the rest of the electrode was masked using photoresist, the nanoplastics were concentrated only in the exposed electrode region, significantly enhancing detection sensitivity. To further investigate the applicability for real-life water samples, we experimented with the technique with readily available bottled drinking water and mineral water, where we spiked these water samples with nanoplastics. It was observed that the resonance frequency shifts were significantly larger for samples with nanoplastics compared to samples without nanoplastics. In addition, Raman spectroscopy and microscopy imaging were used to further confirm the presence and locations of nanoplastics on the electrode surface. This study highlights the combination of electrophoresis and QCM effectiveness in detecting nanoplastics across different water types and their potential for broader applications in environmental monitoring.

Microplastics pollution in the marine environment: A review of sources, impacts and mitigation

Over the past few years, microplastics (MPs) pollution in the marine environment has emerged as a significant environmental concern. Poor management practices lead to millions of tons of plastic waste entering oceans annually, primarily from land-based sources like mismanaged waste, urban runoff, and industrial activities. MPs pollution in marine environments poses a significant threat to ecosystems and human health, as it adsorbs pollutants, heavy metals, and leaches additives such as plasticizers and flame retardants, thus contributing to chemical pollution. The review article provides a comprehensive overview of MPs pollution, its sources, and impacts on marine environments, including human health, detection techniques, and strategies for mitigating microplastic contamination in marine environments. The paper provides current information on microplastic pollution in marine environments, offering insights for researchers, policymakers, and the public, as well as promoting sustainable practices to protect the environment.

Optimising microplastics analysis for quantifying and identifying microplastic fibres in laundry wastewater

Current methods for measuring microplastic fibres (MPF) are cumbersome, time consuming and unscalable for routine high throughput analysis. This study reports a method for rapidly extracting, quantifying and analysing MPFs in laundry wastewater with several key improvements which vastly enhance overall efficiency and scalability of analysis. FT-IR surveying is employed as a preliminary step in analysis to quickly determine what polymers are present in a sample prior to fluorescence treatment. Using random quadrating, whole 25 mm filter membranes were surveyed in <30 min with high recovery rates. In industrial laundry wastewater samples, polyester was the most common MPF, however acrylic, nylon, cotton and rayon were all ubiquitous. The study also demonstrates that an excitation wavelength of 365 nm was optimal for fluorescing PET fibres like polyester which were stained with Nile Red, but not 495 nm, which is commonly used in microplastic analysis. Finally, a custom ImageJ macro was written to automatically enumerate and describe MPFs on filter membranes using just a single stitched fluorescence image. In just a few seconds, concentrations of up to 40,000 fibres/L were analysed in industrial laundry wastewater samples with a lower particle size limit of 20 μm. This study highlights the need for more optimised and scalable analysis workflows which maintain high levels of reliability and accuracy.

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

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

High-resolution NMR spectroscopic approaches to quantify PET microplastics pollution in environmental freshwater samples

Reliable identification and precise quantification of microplastics pollution of the environment are essential prerequisites to comprehend the impact of microplastics on Earth's ecosystems. In this study, we propose a workflow to examine polyethylene terephthalate (PET) contamination of environmental surface waters by applying high-resolution nuclear magnetic resonance (NMR) spectroscopic approaches. The detection of PET by high-resolution NMR spectroscopy enables the unambiguous identification and - at the same time - precise quantification at atomic resolution independent from the size of the particles obtained from surface waters. Monitoring the properties of translational diffusion and relaxation of PET chains present in the samples obtained from Lake Constance water by filtration ('Manta trawls'), extraction and dissolving, hints towards a rather heterogeneous distribution in length of the PET chains. The workflow developed here achieved a limit of detection of 192.2 ng PET and a recovery rate of 88 ± 25% for PET microplastics that was spiked to the Manta trawls. The NMR driven analysis led to a concentration determination of 335 ± 200 ng PET per cubic meter of Lake Constance water. The workflow developed here offers not only a simple and reliable quantitative determination of the mass of PET in environmental samples independent of particle size but is additionally providing insights into the inherent polymeric features of PET, which are not accessible through other established methods of microplastics detection. Therefore, a broad application of the NMR spectroscopic approach presented here can be assumed.

Impacts of microplastics on ecosystem services and their microbial degradation: a systematic review of the recent state of the art and future prospects

Microplastics are tiny plastic particles with a usual diameter ranging from ~ 1 μ to 5 µm. Recently, microplastic pollution has raised the attention of the worldwide environmental and human concerns. In human beings, digestive system illness, respiratory system disorders, sleep disturbances, obesity, diabetes, and even cancer have been reported after microplastic exposure either through food, air, or skin. Similarly, microplastics are also having negative impacts on the plant health, soil microorganisms, aquatic lives, and other animals. Policies and initiatives have already been in the pipeline to address this problem to deal with microplastic pollution. However, many obstacles are also being observed such as lack of knowledge, lack of research, and also absence of regulatory frameworks. This article has covered the distribution of microplastics in water, soil, food and air. Application of multimodel strategies including fewer plastic item consumption, developing low-cost novel technologies using microorganisms, biofilm, and genetic modified microorganisms has been used to reduce microplastics from the environment. Researchers, academician, policy-makers, and environmentalists should work jointly to cope up with microplastic contamination and their effect on the ecosystem as a whole which can be reduced in the coming years and also to make earth clean.

Microplastics in riverine systems: Recommendations for standardized sampling, separation, digestion and characterization

Microplastic (MP) pollution has emerged as a global concern, prompting numerous studies on MP detection. Due to the remaining methodological challenges, it affects the accuracy and reliability of MP's impact assessment on river systems. To address this, the establishment of standardized operating protocols is crucial, encompassing sampling, separation, digestion, and characterization methods. This study evaluates the current tools used for identifying and quantifying MPs in riverine ecosystems, aiming to offer harmonized guidelines for future protocols. Recommendations include adopting a consistent format for reporting MP concentrations and providing improved information on sampling, separation, and digestion for enhanced cross-study comparisons. The importance of quality assurance and quality control is also discussed. Furthermore, we highlight unresolved issues, proposing avenues for further investigation. Suggestions encompass standardizing river sampling methods, optimizing technical steps and analysis processes, and enhancing the accuracy, reliability, and comparability of detection data to advance our understanding of MPs in river environments.

Selective Labeling of Small Microplastics with SERS-Tags Based on Gold Nanostars: Method Optimization Using Polystyrene Beads and Application in Environmental Samples

Microplastics pollution is being unanimously recognized as a global concern in all environments. Routine analysis protocols foresee that samples, which are supposed to contain up to hundreds of microplastics, are eventually collected on nanoporous filters and inspected by microspectroscopy techniques like micro-FTIR or micro-Raman. All particles, whether made of plastic or not, must be inspected one by one to detect and count microplastics. This makes it extremely time-consuming, especially when Raman is adopted, and indeed mandatory for the small microplastic fraction. Inspired by the principles of cell labeling, the present study represents the first report in which gold nanostars (AuNS) are functionalized to act as SERS-tags and used to selectively couple to microplastics. The intrinsic bright signals provided by the SERS-tags are used to run a quick scan over a wide filter area with roughly 2 orders of magnitude shorter analysis time in respect of state of the art in micro- and nanoplastics detection by μ-Raman. The applicability of the present protocol has been validated at the proof-of-concept level on both fabricated and real offshore marine samples. It is indeed worth mentioning that a SERS-based approach is herein successfully applied on filters and protocols routinely adopted in environmental microplastics monitoring, paving the way for future implementations and applications.

Smartphone microscopic method for imaging and quantification of microplastics in drinking water

Analysis of microplastics in drinking water is often challenging due to smaller particle size and low particle count. In this study, we used a low cost and an easy to assemble smartphone microscopic system for imaging and quantitating microplastic particles as small as 20 μm. The system consisted of a spherical sapphire ball lens of 4 mm diameter attached to a smartphone camera as a major imaging component. It also involved pre-concentration of the sample using ZnCl2 solution. The spike recovery and limit of detection of the method in filtered distilled and deionized water samples (n = 9) were 55.6% ± 9.7% and 34 particles/L, respectively. Imaging performance of the microscopic system was similar to a commercial bright field microscopic system. The method was further implemented to examine microplastic particles in commercial bottled and jar water samples (n = 20). The particles count in bottled and jar water samples ranged from 0-91 particles/L to 0-130 particles/L, respectively. In both sample types, particles of diverse shape and size were observed. The particles collected from water samples were further confirmed by FTIR spectra (n = 36), which found 97% of the particles tested were made of plastic material. These findings suggested that the smartphone microscopic system can be implemented as a low-cost alternative for preliminary screening of microplastic in drinking water samples. RESEARCH HIGHLIGHTS: Ball lens based smartphone microscopic method was used for microplastic analysis. Particles of diverse shape and size were found in bottle and jar water samples.

Monitoring of contamination by microplastics on sandy beaches at Vulcano Island (Sicily, Italy) by hyperspectral imaging

In this work, the monitoring and characterization of large microplastics (1-5 mm) collected from sandy beaches of Vulcano Island (Aeolian Islands, Sicily, Italy) were carried out for the first time. Microplastics were sampled from two beaches, "Gelso" and "Sabbie Nere," in three different time periods. The following characteristics of microplastic samples were assessed: quantity, distribution, categories, color, polymer type, size, and shape parameters. The polymers were identified using hyperspectral imaging, whereas an automatic image analysis approach was employed to determine microplastics' morphological and morphometrical attributes. Finally, the microplastic diversity integrated index was computed to obtain information on the potential emission sources of microplastics. It was found that the concentration of microplastics varies from 0.27 particles/kg_dw to 1.35 particles/kg_dw with fragment being the main collected category, with minor amount of pellet, foam, film, and filament. The predominant color of microplastics was by far white, followed by blue and yellow. The identified polymers were polyethylene and polypropylene followed by expanded polystyrene, polyamide, polystyrene, and polyethylene terephthalate. The morphological and morphometrical characterization highlighted a large variability for most size and shape parameters. Finally, the Microplastics Diversity Integrated Index results showed average indices compared to the literature, with higher values for the "Gelso" site (0.656), indicating a higher heterogeneity of sources, with respect to "Sabbie Nere" beach (0.530).

Detection of fibrous microplastics and natural microfibers in fish species (Engraulis encrasicolus, Mullus barbatus and Merluccius merluccius) for human consumption from the Tyrrhenian sea

The occurrence of natural/artificial and synthetic microfibers was assessed in three commercial fish species (Engraulis encrasicolus, Mullus barbatus, Merluccius merluccius) from the Tyrrhenian Sea sold for human consumption. The gastrointestinal tracts of n. 150 samples were analyzed, the isolated microfibers were classified applying a morphological approach, based on the analysis of their morphological features, coupled with the identification of the chemical composition of a subsample of microfibers. All the species contained microfibers at levels ranging from 0 to 49 items/individual and the number of ingested microfibers significantly differed between pelagic and demersal fishes. The evaluation of fiber morphologies highlighted that natural/artificial microfibers were the most numerous among the isolated microfibers, while the dominant colors were blue, black, and clear in all the species. Chemical characterization confirmed the morphological identification and indicated cellulose and polyester as the most common polymer types. Considering the analytical issues that may affect the evaluation of microfiber pollution, the results pointed out the importance of an accurate morphological approach that allows the distinction between different fiber types, before the spectroscopic analyses. Moreover, the implementation of fast and accessible methods to identify microfibers in fish species intended for human consumption will be beneficial also to make an adequate risk assessment to consumer health.

Py-GC-MS analysis for microplastics: Unlocking matrix challenges and sample recovery when analyzing wastewater for polypropylene and polystyrene

Matrix interference and recovery when using pyrolysis gas chromatography (Py-GC-MS) to analyze wastewater for polystyrene (PS) and polypropylene (PP) microplastics (MP) was studied. Raw wastewater underwent a sample preparation train commonly applied for such matrix. The train consisted of six discrete steps to reduce the organic matter content without affecting MP in the sample. One large wastewater sample was collected, homogenized, and subdivided into 21 subsamples. Three samples were analyzed without further sample preparation. The remaining samples were divided in sets of three, and each set underwent an increasing number of steps of the procedure, up to the last set, which underwent the full treatment. The matrix effect on the determination of PS and PP was statistically evaluated by comparing in-matrix and external calibration curves at each step. Recovery of MP was assessed after each step by adding deuterated PS to the samples. A main finding was that there was no significant matrix effect for these polymers throughout the preparation train, suggesting that matrix components did not interfere with the analytical method. However, a significant loss of polymer mass was found between the steps, which may result in MPs falling below detection limits. Therefore, Py-GC-MS could be used for MP quantification before analysis by other techniques which require more extensive matrix removal. A downside of this approach is that analyzing such samples without matrix reduction will increase the need for instrumental maintenance.

Insights into the seasonal distribution of microplastics and their associated biofilms in the water column of two tropical estuaries

The present study describes the seasonal distribution of microplastics (MPs) and their associated biofilms in the water column of the Netravathi-Gurupura estuary, southwest India. An average abundance of 8.15 (±3.81) particles/l and 1.14 (±0.78) particles/l was observed during the wet and dry seasons, respectively. Fibres, films, and fragments accounted for majority of the microplastics. Polyethylene terephthalate, polyethylene, polyurethane, polyester, polystyrene, and high-density polyethylene were the major polymers. The risk assessment revealed a low Pollution Load Index, but the Polymer Hazard Index showed higher toxicity. Diatoms from nine genera were observed attached to the microplastic samples with Amphora and Navicula spp. reported in both estuaries during both seasons. The considerable diversity of diatoms, along with other microbial groups, in microplastic-associated biofilms in this study, highlights the urgent need to understand the structure and development of microplastic-associated biofilms and their role in the vertical and horizontal transport of microplastics in tropical estuaries.

Membrane filter removal in FTIR spectra through dictionary learning for exploring explainable environmental microplastic analysis

Microplastic analysis is a crucial step for locating the environmental contamination sources and controlling plastic contamination. A popular tool like Fourier transform infrared (FTIR) spectroscopy is capable of identifying plastic types and can be carried out through a variety of containers. Unfortunately, sample collection from water sources like rivers usually involves filtration so the measurements inevitably include the membrane filter that also has its own FTIR characteristic bands. Furthermore, when plastic particles are small, the membrane filter's spectrum may overwhelm the desired plastics' spectrum. In this study, we proposed a novel preprocessing method based on the dictionary learning technique for decomposing the variations within the acquired FTIR spectra and capturing the membrane filter's characteristic bands for the effective removal of these unwanted signals. We break down the plastic analysis task into two subtasks - membrane filter removal and plastic classification - to increase the explainability of the method. In the experiments, our method demonstrates a 1.5-fold improvement compared with baseline, and yields comparable results compared to other state-of-the-art methods such as UNet when applied to noisy spectra with low signal-to-noise ratio (SNR), but offers explainability, a crucial quality that is missing in other state-of-the-art methods. The limitations of the method are studied by testing against generated spectra with different levels of noise, with SNR ranging from 0 to - 30dB, as well as samples collected from the lab. The components/atoms learned from the dictionary learning technique are also scrutinized to describe the explainability and demonstrate the effectiveness of our proposed method in practical applications.

Treatment of Synthetic Wastewater Containing Polystyrene (PS) Nanoplastics by Membrane Bioreactor (MBR): Study of the Effects on Microbial Community and Membrane Fouling

The persistent presence of micro- and nanoplastics (MNPs) in aquatic environments, particularly via effluents from wastewater treatment plants (WWTPs), poses significant ecological risks. This study investigated the removal efficiency of polystyrene nanoplastics (PS-NPs) using a lab-scale aerobic membrane bioreactor (aMBR) equipped with different membrane types: microfiltration (MF), commercial ultrafiltration (c-UF), and recycled ultrafiltration (r-UF) membranes. Performance was assessed using synthetic urban wastewater spiked with PS-NPs, focusing on membrane efficiency, fouling behavior, and microbial community shifts. All aMBR systems achieved high organic matter removal, exceeding a 97% COD reduction in both the control and PS-exposed reactors. While low concentrations of PS-NPs did not significantly impact the sludge settleability or soluble microbial products initially, a higher accumulation increased the carbohydrate concentrations, indicating a protective bacterial response. The microbial community composition also adapted over time under polystyrene stress. All membrane types exhibited substantial NP removal; however, the presence of nano-sized PS particles negatively affected the membrane performance, enhancing the fouling phenomena and increasing transmembrane pressure. Despite this, the r-UF membrane demonstrated comparable efficiency to c-UF, suggesting its potential for sustainable applications. Advanced characterization techniques including pyrolysis gas chromatography/mass spectrometry (Py-GC/MS) were employed for NP detection and quantification.

First Data on Anthropogenic Microparticles in the Gastrointestinal Tract of Juvenile Scalloped Hammerhead Sharks (Sphyrna lewini) in the Gulf of California

Scalloped hammerhead sharks (Sphyrna lewini) are critically endangered, according to the International Union for Conservation of Nature Red List, likely due to anthropogenic activities such as intense fishing and pollution. Nowadays, plastic debris contamination is a subject of concern due to its extensive presence in the sea and the digestive tracts of many fish species. The possible effects of plastic debris as a vector of other pollutants are still unknown. We analyzed the digestive tract of 58 hammerhead sharks to investigate the correlation between plastic and other anthropogenic microparticle contamination and their feeding habits in the eastern region of the Gulf of California, revealing a debris contamination occurrence of 79.3%. Out of these, 91.4% corresponded to fibers, and the remaining 8.6% to fragments. The main component of the debris was cellulose (64.4%). According to their diet, these organisms exhibit benthopelagic habits, feeding both in the water column and on the seabed. These results indicate a high level of contamination of anthropogenic cellulosic microfibers in the area. Although cellulosic microfibers are recognized as a biomaterial, they can be harmful to marine species, posing an additional threat to this iconic shark. This changed according to the year, indicating that the anthropogenic microparticle ingestion is related to the discharges of human activities and their seasonality rather than to a selection process by the sharks.