Microplastics in the marine environment

Numerical plastic transport modelling in fluvial systems: Review and formulation of boundary conditions

In recent years, it has become clear that plastic pollution poses a significant threat to aquatic environments and human health. Rivers act as entry points for land-based plastic waste, while a certain fraction of entrained plastics is carried into marine environments. As such, the accurate modelling of plastic transport processes in riverine systems plays a crucial role in developing adequate remediation strategies. In this paper, we review the two main multiphase flow numerical approaches used in plastic transport modelling, comprising Lagrangian Transport Models (LTMs) and Eulerian Transport Models (ETMs). Although LTMs and ETMs can be regarded as complementary and equivalent approaches, LTMs focus on the transport trajectories of individual particles, whereas ETMs represent the behaviour of particles in terms of their mass or volume concentrations. Similar results of the two approaches are expected, while our review shows that plastic transport models are yet to be improved, specifically with respect to the formulation and implementation of boundary conditions, comprising plastic interactions with the channel bed, river bank, and the free surface, as well as interactions with biota. We anticipate that an implementation of these boundary conditions will allow for a better representation of different plastic transport modes, including bed load, suspended load, and surface load. Finally, we provide suggestions for future research directions, including a novel threshold formulation for free surface detachment of plastics, and we hope that this review will inspire the plastic research community, thereby triggering new developments in the rapidly advancing field of numerical plastic transport modelling.

Quantification of anthropogenic debris from small-scale fisheries and community-based aquaculture in marine and coastal ecosystems of Southwestern Madagascar

Most coastal populations in Southwestern Madagascar live on the resources provided by small-scale fishery (SSF), and over the past twenty years, sea cucumber and seaweed farming has grown significantly. This study analyzes the importance of these fisheries and community-based aquaculture (CBA) activities in the contribution of anthropogenic marine debris (AMD) to coastal ecosystems in Southwestern Madagascar. Sampling was conducted in the rainy and dry seasons in three sites with contrasted fishing and farming activities. We have investigated two important coastal ecosystems in these sites, the mangroves and the beaches. At all, about 16,000 AMD items, were collected predominantly plastics. A lower amount of AMD was observed in the rainy season compared to the dry season. The contribution of SSF and CBA activities to the AMD pollution is very important representing 40 % of all AMD in the initial survey. On beaches, 4003 items were found with an average density of 0.17 items m-2. In mangroves, 1039 items were found with an average density of 0.04 items m-2. The most polluted site by SSF and CBA items is Toliara with 3218 debris, Toliara being the one with the highest number of fishermen. The pollution brought by fishing is much more important than that brought by farming. The pollution concerns much more the beaches, where the fishermen start their activities.

Assessment of microplastics pollution level on clam farming and bathing beaches: a case study of Thanh Phu in Ben Tre, Vietnam

This study focused on the investigation microplastics (MPs) with a size of ≤1.0 mm in sand samples from Thanh Phu beach, Ben Tre, Vietnam. MPs in sand from the clam beach (from 39.67 ± 6.67 to 92.00 ± 12.93 items kg-1 dried sand) were higher than those from the bathing beach (from 21.33 ± 8.76 to 51.67 ± 16.11 items kg-1 dried sand), indicating a direct contribution of MPs from coastal aquaculture. For the clam beach, MPs in surface samples (0-4 cm) were lower than in deep samples (4-6 cm). In contrast, MPs in surface samples (0-2 cm) from the bathing beach were higher than deep samples (2-5 cm). A combination of microscopy and Fourier-transform infrared spectroscopy methods confirmed that 62.5% of the representative MPs samples or 18.9% of the suspected MPs samples were plastics. Low-density polyethylene, polypropylene and polyethylene terephthalate were the largest in abundance. Further studies are needed to assess the environmental risk of MPs accumulation.

Investigation into the presence of alkaloids in Areca catechu-based single-use food-contact articles (FCA)

In this work, we have developed a method to investigate the presence of four alkaloids and their migration potential from single-use, biodegradable Areca catechu-derived dinnerware. The seeds of Areca catechu palm, commonly referred to as the betel nut, are known to contain high concentrations of four alkaloids: arecoline, guvacoline, areciadine, and guvacine. Migration of these alkaloids into a food simulant was determined using a single-sided migration cell. The results indicate that carboxylic acid alkaloids, arecaidine, and guvacine, preferentially migrate under the experimental conditions which mimic the conditions of use for dinnerware.

Analysis of the Strength of Polyamide Used for High Pressure Transmission of Hydrogen on the Example of Reinforced Plastic Hoses

The purpose of this study is to evaluate the strength of polyamide utilized in high pressure hydrogen transmission, exemplified by reinforced plastic hoses. The research encompasses a comprehensive investigation of materials employed in hydrogen infrastructure, focusing on their barrier and mechanical properties. It addresses challenges associated with hydrogen storage and transport, presenting various types of tanks and hoses commonly used in the industry and detailing the materials used in their construction, such as metals and polymers. Two materials were analyzed in the study; one new material and one material exposed to hydrogen. Key mechanisms and factors affecting gas permeation in materials are discussed, including an analysis of parameters such as fractional free volume (FFV), solubility coefficient (S), diffusion coefficient, and permeability coefficient. Methods for evaluating material permeation were outlined, as they are essential for assessing suitability in hydrogen infrastructure. Experimental analyses included Fourier Transform Infrared Spectroscopy (ATR), differential thermal analysis (DTA), scanning electron microscopy (SEM), and Energy dispersive X-ray spectroscopy (EDS). These techniques provided detailed insights into the structure and properties of polyamide, allowing for an assessment of its performance under high pressure hydrogen conditions. Pressure was identified as a critical factor influencing both the material's mechanical strength and its hydrogen transport capability, as it affects the quantity of adsorbed particles. According to the DTA investigation, the polyamide demonstrates minimal mass loss at lower temperatures, indicating a low risk of material degradation. However, its performance declines significantly at higher temperatures (above 350 °C). Up to 250 °C, the material shows no notable decomposition occurred, suggesting its suitability for certain applications. The presence of functional groups was found to play a significant role in gas permeation, highlighting the importance of detailed physicochemical analysis. XRD studies revealed that hydrogen exposure did not significantly alter the internal structure of polyamide. These findings suggest that the structure of polyamide is well-suited for operation under specific conditions, making it a promising candidate for use in hydrogen infrastructure. However, the study also highlights areas where further research and optimization are needed. Overall, this work provides valuable insights into the properties of polyamide and its potential applications in hydrogen systems.

Unexplored Mechanisms of Photoprotection: Synergistic Light Absorption and Antioxidant Activity of Melanin

Light exposure has relevant effects both on living organisms and artificial materials. In particular, ultraviolet radiation is known to kill living cells and damage human skin but also degrade important artificial materials like plastics. In nature, the main pigment responsible for photoprotection is melanin, which is able both to prevent penetration of light by absorption and scattering and to block the action of light-generated radicals thanks to its antioxidant properties. The combination of light extinction with antioxidant action is still the most diffused and effective approach to photoprotection. Nevertheless, up to now, these two mechanisms, light extinction and antioxidant activity, have been considered independent. Recent studies showed that exposing melanin to light leads to an increase in its radical content and possibly in its antioxidant activity. Do light extinction and antioxidant activity work in synergy for photoprotection in nature? In this paper, we discuss the steps still needed to answer this intriguing question.

Potential impacts of microplastic pollution on soil-water-plant dynamics

This study was designed to assess the potential impact of microplastic (MP) pollution on soil hydrology, specifically in retaining and releasing moisture. Herein, High-Density Polyethylene (HDPE) MP of different sizes (i.e., 0.5-1, 1-3, and 3-5 mm) and shapes (i.e., fiber, film, and fragment) were evaluated for their effects on water retention curve (WRC) of sandy loam soil, chosen for its agricultural relevance and widespread environmental presence of HDPE. Nine contamination scenarios were simulated with a low MP pollution rate, 0.01% w/w. Van Genuchten models were used to assess plant available water (PAW), wilting point (WP), and water holding capacity (WHC). Results showed that studied MP could significantly affect WRC and PAW mainly by changing WHC rather than WP and that this effect varied with MP shape and size. According to the results, fragment MP had the greatest impact on soil WHC by increasing 36.3%, followed by fibers and films by 19.8% and 15.7%. MP particles significantly increased WHC, while WP remained relatively unchanged. An observed trend indicated that the impact on WHC increased with the size of the MP particles. These findings emphasize the need to manage soil MP pollution to protect plant growth, agriculture, and water dynamics.

Physical and Mechanical Properties of Cement Mortars with Recycled Polyethylene Terephthalate: Influence of Grain Size and Composition

Polyethylene terephthalate (PET) with different grain size after grinding (fine and coarse) was recycled and used as aggregate for non-conventional lightweight cement mortars. The physical and mechanical characteristics were compared to conventional sand-based composites. The workability in the fresh state was evaluated. Accordingly, the composites showed decreases in fluidity with increases in PET percentage weight. Higher thermal insulation and lower mechanical strengths were observed with the increase in plastic dosage due to a density decrease and porosity increase in the composites. Finer grain size PET samples were more resistant (~12-24 MPa) than the coarse-grain samples (~3-23 MPa) due to the higher density and specific surface area of the aggregate. Conversely, higher thermal insulation was obtained with coarse PET addition (~0.6-0.2 W/mK vs. ~0.7-0.35 W/mK). A ductile behavior with discrete cracks after failure was observed after plastic addition to the mixture. Low wettability was observed in PET samples which, although more porous than the sand specimens, showed a hydrophobic behavior which contributed to water repellency. The reported physical, mechanical, thermal, wettability and microstructural features suggest the potential of these composites for both inside and outside applications of non-structural objects.

Spatiotemporal distribution characteristics of physicochemical properties of waste plastics with different landfill age and depth

Plastics are widely used for their excellent properties, and the primary disposal method is sanitary landfilling. Waste plastics, persisting in landfills for long periods, change their surface physicochemical properties. However, research on the physicochemical changes of plastics after landfilling is scarce. This study analyzes the physicochemical characteristics of discarded plastics in landfills, focusing on depths (2-8 meters) and ages (0-30 years). The spatiotemporal distribution of waste plastics was studied using the 3D-Smoothe model. The results revealed that polypropylene (PP) and polyethylene (PE) were the predominant constituents of landfilled plastics. The carbonyl index (CI) and hydroxyl index (HI) accelerated with landfill age but increased and then decreased with landfill depth. Furthermore, the hydrophilicity of waste plastics increases with the landfill age, which is realized as 2 m > 5 m < 8 m in depth. The 3D model analysis indicates that PP displays a wavy downward trend in its spatiotemporal distribution, whereas PE exhibits a vortex-like downward trend. The toughness and strength of waste plastics rapidly decline in the early stages of landfilling and then stabilize. However, variations are noted at a depth of 5 m. The influence of landfill age on the mechanical properties of waste plastics is more significant than that of landfill depth by 3D model analysis. As the age and depth of landfills increase, there is a corresponding rise in the number of surface cracks and defects, a rise in surface roughness, and an increase in the abundance of surface elements. This study provides a scientific basis for understanding the environmental risks of landfilled waste plastics.

Developmental Toxicity of Micro(Nano)Plastics (MNPs) Exposure in Mammals: A Mini-Review

Micro(nano)plastics (MNPs) pose a significant threat to both ecological environments and human health. This review systematically examines the developmental toxicity of MNPs in mammals, with a particular focus on the impact of maternal and paternal exposure on offspring. Evidence indicates that MNPs can cross placental barriers, inducing abnormal development of embryos, fetuses, and placentas. This disruption leads to a range of adverse outcomes, including neurodevelopmental abnormalities, behavioral disorders, reproductive system damage, etc., in offspring. Through a comprehensive analysis of the existing literature, this review aims to provide a foundation for future research on the developmental toxicity of MNPs and highlight the urgent need for action to mitigate the detrimental effects of MNPs on human health and ecosystem integrity.

Molecular insights into supercritical water gasification process of polyoxymethylene plastics

Effective plastic management is crucial in addressing the growing environmental challenges posed by plastic pollution. Among various plastics, polyoxymethylene (POM) stands out as a widely used engineering thermoplastic with significant applications in industries . Innovative recycling solutions are essential to mitigate its environmental impact. This study investigates the supercritical water gasification (SCWG) of POM plastics at a molecular level using reactive molecular dynamics simulations. The research aims to provide insights into the factors influencing the SCWG process. Key findings reveal that temperature significantly affects reaction mechanisms, while the primary syngas products include hydrogen , carbon monoxide, and carbon dioxide. A notable trend observed is the increase in activation energy as water content increases, highlighting the importance of optimizing hydration levels for efficient conversion. The calculated activation energies range from 106 to 135 kJ/mol, aligning well with experimental findings (160 kJ/mol). The study validates the computational approach by demonstrating excellent agreement between simulation results and experimental findings on the molar fraction of gas and activation energy, underscoring its reliability as a predictive tool for process design and optimization. Furthermore, the research contributes to sustainable waste management by offering strategies to enhance SCWG efficiency.

Microplastics in Bays along the Central Texas Coast

Estuarine and bay environments, which can act as sediment traps along the inner parts of continental shelves, may host significant depositional hotspots for plastic debris. This research targets Texas coastal bays (Matagorda and San Antonio), to better understand microplastic contamination in sediments and provide insight into the processes controlling its distribution. Microplastic extraction and quantification methods employed include sediment sieving, elutriation, microscopy, and spectroscopy. This study found low concentrations (ca. 10s-100s particles kilogram-1 sediment or 20-200 × 104 items meter-3 wet sediment) and negligible correlations between analyzed deposit constituents (R2 for grain size = -0.14 to 0.12, organic content = 0.08, water depth = -0.11, distance to shore = -0.14). The highly dynamic role of wind-driven mixing and openness to the Gulf of Mexico leads to the high flushing rate of sediment and microplastics out of the bays. Larger microplastic particles (fragments: 178 ± 93 μm, fibers: 0.5 to 2.0 mm) were consistently deposited with finer sediments, indicating high transportability. Microplastic resuspension into bay waters has significant implications for limiting microplastic accumulation within bay sediments. This work provides a baseline for future studies quantifying the roles of wind and residence time on microplastics in coastal environments.

Microplastic pollution in the water column and benthic sediment of the San Pedro Bay, California, USA

The concentration, character, and distribution of microplastics in coastal marine environments remain poorly understood, with most research focusing on the abundance of microplastics at the sea surface. To address this gap, we conducted one of the first comprehensive assessments of microplastic distribution through the marine water column and benthic sediment during the wet and dry season in the coastal waters of the San Pedro Bay Southern California, USA. Microplastic concentrations in the water column did not vary significantly across season but were significantly higher in nearshore environments and at the surface of the water column. Sediment samples contained significantly more microplastics in the wet season and in offshore environments. Black particles were the most dominant color, while fibers were the most abundant morphology, accounting for over 50% of both water column and sediment microplastics. Polyethylene and polypropylene were identified as the most abundant polymers in the water column regardless of morphology type. Tire and road wear particles were found through the study domain. Average microplastic concentrations in the San Pedro Bay were estimated to be 8.65 × 105 ± 7.60 × 105 particles/km2 and 3.19 ± 2.96 particles/m³. This study highlights the complexity of microplastic concentration, character, and distribution in marine environments and demonstrates that surface only sampling strategies significantly underestimate microplastic concentrations. Our findings underscore the need for continued and expanded research into microplastic distribution and transport dynamics across the marine environment to aid in understanding, managing, and mitigating plastic pollution in coastal marine systems.

Rapid identification of marine microplastics by laser-induced fluorescence technique based on PCA combined with SVM and KNN algorithm

The laser-induced fluorescence technique has the advantage of fast and non-destructive detection and can be used to classify types of marine microplastics. However, spectral overlap poses a challenge for qualitative and quantitative analysis by conventional fluorescence spectroscopy. In this paper, a 405 nm excitation laser source was used to irradiate 4 types of microplastic samples with different concentrations, and a total of 1600 sets of fluorescence spectral data were obtained. The 726 data points contained in each sample spectrum were first analyzed by PCA, and the 4 microplastics were differentiated by their position in the PCA score plot. The classification and identification are then performed by SVM, KNN, PCA-SVM and PCA-KNN algorithms respectively. The classification accuracy of microplastics in seawater using SVM and KNN algorithms is higher than 86%. The classification accuracy can be increased to 100% by PCA combined with SVM and KNN algorithm. Concentration inversion was conducted by SVM and KNN algorithms after classification. The correlation coefficients between the predicted values and the actual values were higher than 0.8, and the RMSE was less than 0.47%, which indicated that both algorithms had good prediction results. These machine learning methods provide accurate and reliable identification results in the rapid identification of microplastic types and their concentrations without complex spectral data preprocessing and fluorescence background removal algorithms.

Can the insects Galleria mellonella and Tenebrio molitor be the future of plastic biodegradation?

Plastics have been an integral part of human lives, enhancing the functionality and safety of many everyday products, contributing significantly to our overall well-being. However, petroleum-based plastics can take hundreds or even thousands of years to decompose, resulting in an unprecedented plastic waste accumulation in the environment. Widely used conventional plastic disposal methods as landfilling and incineration are also environmentally harmful, frequently leading to soil/water contamination and the release of microplastics. To overcome these limitations, researchers have been investigating novel sustainable alternatives for plastic waste management, such as the use of microorganisms, microbial-based enzymes, and, more recently, some insect larvae, being Galleria mellonella and Tenebrio molitor the most promising ones. In this review, we explore different methods of plastic waste disposal focusing on recent discoveries regarding biological plastic degradation using insects as alternative methods. We also discuss the plastic degradation mechanisms employed by G. mellonella and T. molitor larvae known so far, as salivary enzymes and the pool of microorganisms in their gut. Finally, this review highlights key challenges in plastic biodegradation, such as standardization and experimental comparability, while proposing innovative perspectives like using insects as bioreactors and exploring unexplored research directions.

Microplastic contamination in the highly polluted Tietê River (São Paulo, Brazil): an unsustainable human-nature relationship

Most domestic and industrial waste, along with plastic litter from São Paulo city, flows into the Tietê River. Microplastics (MPs) from water column and sediment samples of the Tietê River, a marginal lagoon, and Peixe River (tributary) were analyzed to verify microplastic contamination downstream the São Paulo metropolitan region. Water samples were collected after the rainy season (April 2021) and during the dry season (August 2021), with a plankton net. Sediment samples were collected only in April 2021, with a dredge. Samples were submitted to wet peroxidation (H2O2 + Fe (II) at 70 °C) and then passed through metal sieves (minimum 0.053 mm, maximum 4 mm). Microscopic counting characterized microplastic size, form, and color. µFTIR analysis was performed to verify particle chemical composition. For water, there was an increasing gradient of MPs: Peixe River < Tietê lagoon < Tietê River. For sediments, contamination in the main river and the marginal lagoon is of the same magnitude (105 MPs/kg). Size, form, and color proportions were similar when comparing the water and sediment. Small-sized transparent and blue fibers predominated. The main types of polymers were PET (23.5%), followed by HDPE, polyester, and polyethylene (14.7% each). The lentic condition of the lagoon did not increase particles in the sediment when compared to the main river. Contamination in the Tietê River water column was higher after the rains in São Paulo even 300 km downstream. Integrated water-sediment analyses were important to understand distinct processes on both spatial and temporal scales.

Microplastic Pollution and Its Ecological Risks in the Xisha Islands, South China Sea

China is facing increasing marine microplastic pollution. Despite the fact that the South China Sea is the largest marine area in China, the ecological danger and present state of microplastic contamination in this region have not been systematically and comprehensively investigated. This study analyzed the abundance, distribution, and characteristics of microplastics in different environmental media and biological samples from the Xisha Islands in the South China Sea, and then the ecological risk assessment of microplastic pollution in this area was conducted. The findings indicated that the quantities of sediments, soil, water, fish, and birds were 41.56 ± 19.12 items/kg, 92.94 ± 111.05 items/kg, 2.89 ± 1.92 items/L, 2.57 ± 2.12 items/ind, and 1.702 ± 1.50 items/ind, respectively. By evaluating the pollution load index (PLI), polymer hazard index (PHI), and potential ecological risk index (PERI), the PLI of the Xisha Islands in the South China Sea as a whole indicated that the hazard level was slightly polluted, the PHI was at a high-risk level, and the PERI samples were at no risk, except for the soil and seawater, which were at a medium-risk level.

How does alkaline-thermal pretreatment followed by anaerobic digestion affect the content of polyethylene terephthalate and polyamide 66 microplastics?

Microplastics (MPs) are ubiquitous and increasing in quantity, causing raising concern. Wastewater treatment plants (WWTPs) are a point source for both aquatic environments and soil, through the use of sludge in agriculture. Understanding the fate of MPs within the wastewater and sludge lines of a treatment plant and, possibly, enhancing their removal will improve the safe reuse of sludge and water effluent and the wastewater biorefinery concept application. This study investigates the effects of alkaline-thermal pretreatment of sludge, followed by anaerobic digestion, on the physical and chemical characteristics of polyethylene terephthalate (PET) and polyamide 66 (PA(66)) contained. Experiments were conducted to evaluate the influence of different NaOH concentrations, temperatures, and reaction times on the degradation of the MPs in anaerobic digestion. PET MPs exhibited relevant mass reduction and structural changes in relation to the NaOH concentration and temperature. PA(66) MPs showed limited chemical alterations, indicating higher resistance to degradation. Batch anaerobic digestion tests of pretreated samples did not modify them further. Chemical characterization of MPs was performed using both Attenuated Total Reflectance-Fourier Transform Infrared spectroscopy (ATR-FTIR) and Focal Plane Array-Fourier Transform-Imaging-Micro-Spectroscopy (FPA-μFTIR-Imaging), revealing distinct trends between surface-level and bulk material changes in the MPs. The results highlighted that ATR-FTIR recorded lower carbonyl index values compared to FPA-μFTIR-Imaging. These findings emphasized the importance of using complementary analytical techniques to thoroughly understand MPs degradation. The outcomes suggest that tailored pretreatment strategies are essential to enhance MPs removal in WWTPs, ensuring safer sludge reuse within a circular economy framework.

Ingested microplastics: a comparative analysis of contaminated shellfish from two sites in the Makassar Strait

Marine plastic debris, particularly microplastics (MPs), is an urgent and significant threat to the global marine environment. The emergence of MPs in the marine environment and their potential presence in human-consumed seafood necessitates immediate investigation. In light of this, a study was conducted on the occurrence of MPs in shellfish collected from two locations in Makassar Strait with distinct oceanographic conditions. Three commonly consumed shellfish species (Perna viridis, Meretrix meretrix, and Mactra chinensis) were collected by fishermen and examined for microplastic contamination, with a total sample size of 170 individuals. Microplastics were extracted from the soft tissue of the bivalves using the alkaline digestion method. The results revealed a significantly higher number of microplastics ingested by P. viridis and M. chinensis in samples collected from the Sanrobengi Islands (14.64 MPs/individual and 2.29 MPs/individual, respectively), compared to the P. viridis and M. meretrix from Mandalle coastal area (0.70 MPs/individual and 1.00 MPs/individual, respectively). The predominant microplastic form detected was blue microfibres. A prevalence of MP contamination between 58 and 100% and the results of Fourier Transform Infrared Spectroscopy (FTIR) analysis indicated that polystyrene was the dominant polymer present, threatening the welfare of the bivalve mollusks and posing potential health risks to seafood consumers. The results emphasize the urgent need for pollution control measures such as reducing plastic waste discharges and improving waste management systems. In addition, a comprehensive study focusing on the long-term ecological and health effects of microplastic pollution is necessary to guide future policy interventions.

Zebrafish and Drosophila as Model Systems for Studying the Impact of Microplastics and Nanoplastics ‐ A Systematic Review

Microplastics and nanoplastics (MNPs) are byproducts of plastics created to benefit humanity, but improper disposal and inadequate recycling have turned them into a global menace that we can no longer conceal. As they interact with all living organisms, including humans, their mechanism of interaction and their perilous impact must be meticulously investigated. To uncover the secrets of MNPs, there must be model systems that exist to interlink the two major scenarios: they must represent the environmental impact and be relevant to humans. Therefore, zebrafish and Drosophila are perfect to describe these two cases, as they are well studied and relatable to humans. In this review, 39% zebrafish studies reported higher mortality and hatching rates at greater MNP concentrations, severe oxidative stress as seen by raised malondialdehyde (MDA) levels, and reduced superoxide dismutase (SOD) activity. About 50% of studies showed severe neurotoxic behavior with drop of locomotor activity, suggesting neurotoxicity. MNPs have a significant impact on fertility rate of Drosophila. More than half of the studies revealed genotoxicity in Drosophila as observed by wing spot assays and modified genomic expressions associated with stress and detoxification processes. These findings emphasize the potential of MNPs to bioaccumulate, impair physiological systems, and cause oxidative and neurobehavioral damage. This study underscores the importance for thorough risk evaluations of MNPs and their environmental and health consequences.

Investigating macro marine litter and beach cleanliness along Southern Vietnam beaches

Plastic contamination is a major issue for marine ecosystems, with macro-litter posing a growing threat globally. This study assesses macro-marine litter on Vung Tau beaches, Southern Vietnam, providing baseline data for marine litter pollution and identifying critical action plans for plastic control. Survey results showed litter density ranging from 0.1768 to 0.4464 items m-2 across twelve sites. Using the Clean Coast Index (CCI), 16.7 % of beaches were rated as "Clean" and 83.3 % as "Moderate," while the Plastic Abundance Index (PAI) revealed 91.7 % of sites had "Moderate" plastic levels. Human activities, such as tourism and insufficient waste management, were key contributors. Addressing this issue requires raising awareness, promoting behavioural change and tourist perceptions, and enhancing waste management efforts. Prioritizing marine protection programs is crucial for effectively eliminating marine litter and plastic waste.

Laser Direct Infrared Spectroscopy: A cutting-edge approach to microplastic detection in environmental samples

Microplastic pollution has emerged as a significant global environmental concern, affecting marine, terrestrial, and atmospheric ecosystems. As microplastic contamination continues to intensify, the need for precise, efficient, and scalable detection method is growing. This review highlights recent advancements in microplastic detection technologies, with a particular focus on Laser Direct Infrared (LDIR) spectroscopy. Utilizing a Quantum Cascade Laser (QCL), LDIR offers rapid, sensitive, and automated detection capabilities. It significantly reduces analysis time compared to conventional techniques such as Fourier Transform Infrared (FTIR) and Raman spectroscopic techniques, making it ideal for large-scale environmental monitoring. Its ability to identify particles as small as 10 μm, combined with enhanced wavelength accuracy, positions LDIR as a promising tool for microplastic analysis across various environmental matrices. Despite some limitations, such as a narrower spectral range, LDIR's superior speed and precision make it a critical advancement for understanding and addressing the global microplastic crisis.

Impact of particle size and oxide phase on microplastic transport through iron oxide-coated sand

The presence of microplastics in aquatic environments threatens the ecological system and human health. This study investigates the transport and retention of polystyrene microplastics (PSMPs) in clean sand, and hematite-, goethite-, and magnetite-coated iron oxide - sands as a function of size ratio and ionic strength. The breakthrough curves (BTCs), retention profiles, and hydraulic pressure were measured through soil-column experiments, and the retention of PSMPs was assessed from the observed BTCs, RPs and first-order attachment coefficients. In addition, the maximum attachment capacity was evaluated to assess the long-term retention of PSMPs. Experimental data showed that the retention of PSMPs increased in the order of goethite-, hematite-, and magnetite-coated sands in all size ratios, which is consistent with the order of attraction energy calculated by extended Derjaguin-Landau-Verwey-Overbeek theory. The findings demonstrated the feasibility of mitigating the transport of microplastic particles using naturally abundant iron-rich soils.

Quantifying microplastics concentration of invertebrates from three Antarctic fjords

Microplastics, small pieces of plastic measuring less than five millimeters, have spread to all ecosystems, even those in the Southern Ocean around Antarctica. In particular, microplastics have been found contaminating water in emerging fjords, or inlets created by deglaciation, along the Antarctic Peninsula. Microplastics contamination puts fjord communities, which are unique and dominated by benthic species, at high risk for microplastic exposure leading to issues with feeding, endocrine disruption, and exposure to adsorbed toxins, all of which lower fecundity and survivability. The objective of this study was to quantify microplastics in invertebrates grouped according to feeding type. Invertebrates were collected from the Western Antarctic Peninsula fjords during 2017 and 2020 from three fjords via a mini-Agassiz trawl to quantify microplastic concentrations and identify polymer composition using Micro-ATR-FTIR. In 2017, 2.39 microplastics individual-1 were identified, while 5.01 microplastics individual-1 were identified in 2020. Out of the 24 polymers and polymer associates identified, the most common polymers were polypropylene, polycarbonate, polyamide, and polystyrene. Overall, the most common microplastic color category was black/brown/gblay, and fragments were the most common shape identified. Microplastics presence was significantly higher in the invertebrate organisms compared to procedural blanks (p < 0.001), but feeding mechanism was not found to be a predictor of microplastic bioaccumulation. Microplastics concentrations in invertebrates differed between fjords in 2017 (p = 0.010) but not in 2020. Complementing previous research on microplastics in Southern Ocean fjordic water, this study reveals new evidence of microplastics in Antarctic fjordic inhabitants.

The wheel of time: The environmental dance of aged micro- and nanoplastics and their biological resonance

The aging of micro- and nanoplastics (MNPs) significantly affects their environmental behavior and ecological impacts in both aquatic and terrestrial ecosystems. This review explored the known effects of aging on MNPs and identified several key perspectives. Firstly, aging can alter the environmental fate and transport of MNPs due to changes in their surface properties. This alteration accelerates their accumulation in specific habitats like oceans and soils, resulting in increased bioaccumulation by organisms. In addition, aged MNPs interact differently with living organisms than their pristine counterparts by influencing the attachment of biofilms and other microorganisms in aquatic ecosystems. Moreover, the aging processes of MNPs exhibit adverse effects on aquatic and terrestrial organisms via increasing the bioavailability and potential toxicity of MNPs as degradation products are released. Last but not least, the biodegradation potential of MNPs can be altered by the aging process, thus affecting their degradation rates and pathways in the environment. However, there are still knowledge gaps regarding the natural aging behaviors of MNPs, such as the aging mechanisms of different types of plastic, the influence of environmental factors, the release of pollutants, and even the effects of aging on their transformation in different ecosystems. Therefore, a great contribution can be made to sustainable plastic use and environmental preservation by studying the natural aging of common MNPs and their subsequent biological effects.

Onboard measurement of polyethylene microplastics on a research vessel using Raman micro-spectroscopy: A preliminary study for testing feasibility

Microplastic pollution in marine environments poses significant environmental risks due to its widespread presence. Traditional micro-imaging measurement of microplastics often rely on post-cruise laboratory analyses. In this study, we explored the feasibility of onboard microplastic measurement using Raman spectroscopy, with a focus on polyethylene (PE). A measurement system was developed, and two concentration estimation approaches were proposed. To evaluate recovery and validate the methodology, artificial microplastic samples were prepared, yielding a recovery rate of 94.8 % ± 10.4 %. Environmental samples were then analyzed using the developed system, with results validated against conventional Fourier-transform infrared (FTIR) spectroscopy. The estimated PE concentration was 583 pieces/m3 (95% confidence interval: [2, 1542] pieces/m3) using the direct approach and 1453 pieces/m3 (95% credible interval: [291, 92,837] pieces/m3) using the Bayesian approach. Both estimates were consistent with the 333 pieces/m3 obtained through validation with FTIR, indicating adequate accuracy. However, the wide confidence intervals highlight the need for improved precision. While challenges remain, this study provides a comprehensive experimental procedure and introduces a robust data analysis framework, which could offer a foundational methodology for future onboard microplastic measurement research.

Estimation of macroplastic yield from river basin to coastal area: A case study of the Klang River, Malaysia

Plastic pollution in aquatic ecosystems has become a critical global environmental challenge, threatening biodiversity, water quality, and human health. This study investigates macroplastics distribution and characterization in the highly polluted Klang River, Malaysia, and proposes a protocol to compute total macroplastic yield in the river basin. A total of 240 macroplastic items were collected over a 20-km stretch from the river mouth inland, with an average of 0.91 ± 0.80 g/item (dry weight). Scanning Electron Microscopy revealed that the macroplastics had weathered slowly in the environment, potentially breaking down into smaller microplastic particles. Biofilms and dead phytoplankton were observed on the plastic surfaces, suggesting that plastic debris may act as vectors for other pollutants. The study used SWAT modelling to simulate physical processes in the Klang River Basin and compute pollutant loads through a loading computation procedure. A macroplastic rating curve was created using river discharge, macroplastic loadings, and associate parameters to estimate plastic loading in the river. The fitted equation models macroplastic loading as a function of river discharge and width, expressed as: log(y) = 1.88216-7.36528log(x) - 4.00491log(x2). Here, log(x) represents the ratio of river discharge to river width, while log(y) denotes macroplastic loading adjusted for sampler width and river width. Results indicated that macroplastic transport in the river system is linked to flow rates and sediment yield, which vary due to topographical factors, with an estimated macroplastics yield in the Klang River Basin of 11,600 kg/day. The findings suggest that a river-specific monitoring programs should be conducted to generate comprehensive datasets, integrating both macroplastics and microplastics abundance, which can be utilized for projecting plastic emissions from Malaysian rivers and comparing data with other river basins in the Southeast Asia.

Assessing microplastic pollution along the Caribbean coast of La Guajira, Colombia

Microplastic pollution has become a global environmental issue, severely impacting marine ecosystems. In Colombia, understanding of marine microplastic pollution remains limited, necessitating targeted efforts for prevention and conservation. This study presents the first assessment of microplastics along 125 km of the Caribbean coast of La Guajira region in Colombia. Sediment samples from seven beaches (Palomino, Dibulla, Camarones, Riohacha, Valle de los Cangrejos, Mayapo, and Jimatsu) were analyzed for microplastic during two sampling periods, encompassing color, morphology, and polymer composition determined by Fourier transform infrared spectroscopy. Microplastics were found at Dibulla, Camarones, Riohacha, and Mayapo beaches during the two sampling periods (2.4 ± 0.6 to 12 ± 2 particles/m2 in one period, and 3.2 ± 0.8 to 22 ± 7 particles/m2 in the other). Filaments from fishing activities predominated, with microplastics mostly light-colored and composed of polypropylene, polyethylene, and polystyrene. While microplastic concentrations varied among beach use, differences between the two sampling periods were not statistically significant.

Enhanced uptake of perfluorooctanoic acid by polystyrene nanoparticles in Pacific oyster (Magallana gigas)

The effects of plastic pollution on marine organisms is of growing concern. The hydrophobic surface of plastics adsorbs organic contaminants and can alter the rate of chemical uptake in fishes. Per-fluorinated organic chemicals such as Perfluorooctanoic acid (PFOA) are highly hydrophobic toxic chemicals that adsorb to hydrophobic surfaces. We hypothesized that the presence of nano-sized plastic particles adsorbs PFOA and alter both the physical-chemical properties of the plastics and also enhance PFOA uptake into organisms. Using radiolabelled 14C-PFOA, we measured direct unidirectional uptake of PFOA in juvenile Pacific Oysters (Magallana gigas) at different (0.025, 0.50, and 0.100 mg/L) concentrations, for different exposure periods (1, 2, 4, and 6 h) and investigated whether varying concentrations (0.1, 0.5, 1 mg/L) of either 500 nm or 20 nm polystyrene nanoparticles (PS-NPs) differentially altered the uptake rate of PFOA. Our results demonstrate that PFOA adsorbs to the surface of PS-NPs, altering PS-NP behaviour in solution and significantly increases the rate of uptake of PFOA in exposed Pacific oysters. PFOA uptake at 0.1 mg/L was increased 2.3-fold in the presence of 1 mg/L 500 nm PS-NP and 3.2-fold in the presence of 1 mg/L 20 nm PS-NP. In a separate study to examine if PS NPs potentiate the biochemical response to PFOA, both 500 and 20 nm PS-NP at 100 mg/L increased the 1 mg/L PFOA-induced oxidative stress by 2.5-fold and 3-fold respectively. These findings demonstrate that nanoplastics as co-contaminants in marine systems are able to adsorb PFOA and significantly potentiate its uptake and toxicity.

Revealing antagonistic interactions in the adverse effects of polystyrene and poly(methyl methacrylate) microplastics in bumblebees

Microplastics pose a significant ecological threat, yet their actual impact on terrestrial ecosystems and organisms remains poorly understood. This study investigates the effects of two common microplastics, poly(methyl methacrylate) (PMMA) and polystyrene (PS), on the pollinator Bombus terrestris, exploring their combined and sublethal effects at three different concentrations (0.5, 5 and 50 mg l-1). PMMA and PS single exposure reduced bee survival in a concentration-dependent manner, whereas combined exposure (MIX) had no significant effect. PS reduced bee sucrose responsiveness, PMMA had no significant effect and MIX enhanced it. Learning and memory tests showed impaired mid-term and early long-term memory in bees exposed to PMMA and PS, with concentration-dependent effects. Interestingly, MIX exposure had no effect on memory retention. Our findings emphasize the differential effects of individual microplastics on bumblebee behaviour, suggesting potential risks to pollinator survival, cognitive function and possibly overall colony health, but also unexpected antagonistic interactions between these pollutants. The PS-PMMA antagonistic interactions highlight a challenge in assessing the toxicity of microplastics. Combined effects may not mirror the individual toxicity of PS and PMMA, highlighting the need for a careful assessment of polymer interactions, especially in environments or organisms contaminated by different microplastics.

Rhamnolipid: nature-based solution for the removal of microplastics from the aquatic environment

Over the past two decades, research into the accumulation of small plastic particles and fibers in organisms and environmental settings has yielded over 7,000 studies, highlighting the widespread presence of microplastics in ecosystems, wildlife, and human bodies. In recent years, these contaminants have posed a significant threat to human, animal, and environmental health, with most efforts concentrated on removing them from aquatic systems. Given this urgency, the purpose of this study was to investigate the potential of rhamnolipid, a biosurfactant, for the removal of microplastics from water. Specifically, this study evaluates the effects of water matrix, initial pH of the solution (7.0, 7.5, 8.0, 8.5, 9.0, 9.5, and 10.0), concentrations of alum (5, 10, 20, 30, 40, and 50 mg/L), and concentrations of rhamnolipid (1, 5, 10, 20, 40, 80, and 100 mg/L). Optimum removal was achieved at alum and rhamnolipid concentrations of 5.0 mg/L and 1.0 mg/L, respectively, with a solution pH of 8.0. In both types of water tested, a removal efficiency of about 74% was determined, indicating the potential of rhamnolipid as a nature-based solution to control microplastic pollution in surface waters.

The feeding mode effect: influence on particle ingestion by four invertebrates from Sub-Antarctic and Antarctic waters

Microplastic (MP) pollution is a significant threat to marine environments not only due to its widespread presence but also because of the alarming emergence of ingestion records among benthic organisms. In this study, MP prevalence was assessed in the stomach of the crustaceans Lithodes santolla and Grimothea gregaria and the gastropods Nacella deaurata and N. concinna. Particles were analyzed with Fourier-transform infrared (FTIR) spectroscopy. Overall, the analysis revealed that the particles were mainly microfibers composed of cellulose/rayon (60%), followed by MPs (30%), and undetermined not registered in the library (10%). Higher prevalence was found in marine benthic grazers compared to scavengers, with the latter showing low particle prevalence in their stomach contents. Grazers presented a significantly higher abundance per individual but a lower size of ingested particles compared to scavengers. When grouped by trophic levels, tertiary consumers presented significantly lower abundances per individual but larger sizes of the ingested particles. Pearson's correlations showed no significant associations between particle abundance/size and species body size. The results of this study may suggest that continued MP pollution in marine environments and the associated accidental ingestion by marine organisms will alter the energy flow and organic matter availability in benthic food webs, with species that perform certain functional traits more susceptible to being affected.

Influence of mesh selectivity on risk assessment of marine microplastics

In this study, environmental microplastic samples (>30 μm) were collected from surface seawater and the water column, characterized, and used to assess ecological risks. The influence of mesh selectivity on ecological risks was also evaluated through subsampling. Results show that surface microplastic concentrations (>30 μm) range from 92 to 3306 pieces/m3 along Japan's southwest coast, with significant increases at Stas. 2 and 1. Subsurface vertical concentration near Okinawa ranges from 991 to 1992 pieces/m3, with denser, more toxic polymers more frequently observed in deeper waters, suggesting that polymer types may be sorted by marine structure. Risk assessments revealed very high risks near main islands and populated regions, while remote regions had lower risks. Further analysis revealed that ecological risk estimates are significantly influenced by mesh selectivity, with variations in particle size distribution and polymer type composition resulting in changes of up to 100-fold at the same location when different mesh sizes were used, suggesting that current framework is not ideal for risk assessment of microplastics. This study is the first to demonstrate that samplers with different mesh sizes can lead to substantial differences in risk assessments, even at the same location. These findings underscore the critical impact of mesh selectivity on ecological risk estimates and highlight the need for standardized sampling protocols in microplastic research.

Combined toxicity of polystyrene microplastics and perfluorobutane sulfonate on mouse liver: Impact on lipid metabolism and gut-liver axis disruption

Microplastics (MPs) in the environment can adsorb perfluoroalkyl substance (PFAS), leading to combined toxicity in various organisms. Most researches have focused on single-exposure effects on mouse liver, with limited studies on the mechanisms behind the combined effects of polystyrene microplastics (PS-MPs) and perfluorobutane sulfonate (PFBS). This study analyzed the single and combined toxic effects of PS-MPs (10 mg/kg) and PFBS (30 mg/kg PFBSL or 300 mg/kg PFBSH) on mouse liver. Results indicated that PFBS was adsorbed by PS-MPs, affecting PFBS accumulation. Co-exposure significantly increased liver injury biomarkers in serum, associated with heightened oxidative stress, inflammation, and lipid accumulation. Metabolomics analyses revealed that the co-exposure had the most pronounced impact on lipid metabolism disorders, followed by PFBS and PS-MPs. Additionally, exposure to PS-MPs and PFBS induced gut microbiota dysbiosis and gut barrier disruption, disturbing lipid metabolism - particularly bile acids and short-chain fatty acids - along the gut-liver axis, thereby causing liver injury. Notably, co-exposure, particularly with high-concentration PFBS, significantly aggravated these effects. This study highlights the combined effects of PS-MPs and PFBS on liver function though lipid metabolism disorders and gut-liver axis imbalance, providing valuable insights into the health risks associated with these pollutants.

Combined exposure effects: Multilevel impact analysis of cycloxaprid and microplastics on Penaeus vannamei

In real environments, multiple pollutants often coexist, so studying the impact of a single pollutant does not fully reflect the actual situation. Cycloxaprid, a new neonicotinoid pesticide, poses significant ecological risks due to its unique mechanism and widespread distribution in aquatic environments. Additionally, the ecological effects of microplastics, another common environmental pollutant, cannot be overlooked. This study explored the ecotoxicological effects of cycloxaprid and microplastics, both alone and in combination, on Penaeus vannamei over 28 days. The results revealed significant physiological impacts, with notable changes in the shrimp immune system and hepatopancreatic energy and lipid metabolism. Key findings include alterations in hemocyanin, nitric oxide, and phenol oxidase levels, along with disturbances in Na+/K+-, Ca2+-, and Mg2+-ATPase activities. Additionally, neural signaling disruptions were evidenced by fluctuations in acetylcholine, dopamine, and acetylcholinesterase levels. Transcriptomic analysis revealed the profound influence of these pollutants on gene expression and metabolic processes in the hepatopancreas and nervous system. This comprehensive assessment underlines the potential growth impacts on shrimp and underscores the ecological risks of cycloxaprid and microplastics, offering insights for future risk assessments and biomarker identification.

Implementing differential recovery corrections enhances accuracy of mass balances on microplastics in wastewater treatment

This study examined the impact of using different analytical recovery practices to correct MP concentrations on the performance of count and mass balances of primary wastewater settling. Spiking tests using standard MPs were conducted to evaluate the influence of MP size and sample type on recovery. The derived recovery values were then used to correct MP concentrations and loads in a full-scale primary treatment facility. The results reveal substantial differences in recovery that were dependent upon MP size and sample type, underlining the necessity of incorporating these discrepancies when estimating MP concentrations. Omitting recovery considerations during MP concentration reporting led to underestimations of approximately 40 %. In contrast, incorporating MP size and sample type during recovery calculations fostered a more accurate representation of MP concentrations, thereby enhancing the closure of balance models. While a count balance model was not apparently improved through the use differential recovery, the mass balance model showed a significant improvement in closure, reducing the lack of balance from 30.2 % to 17.2 %. This discrepancy was primarily attributed to the differing proportions of the primary sludge stream load in each model. These findings highlight the importance of incorporating differential recovery into mass balance models and demonstrate the complementary nature of count and mass balance approaches in understanding the fate and transport of MPs in WWTPs. The results of this study have significant implications for improving environmental assessments, policies and engineering design of wastewater treatment processes.

Impacts of climatic stressors on dissolved organic matter leaching from microplastics and their effects on biogeochemical processes: A review

This review explores the potential impact of microplastic-derived dissolved organic matter (MP-DOM) on biogeochemical processes associated with global carbon and nitrogen cycles, with consideration given to the possible influence of irregular climate changes. We synthesize literature on MP-DOM leaching behaviors during various natural aging processes, such as heavy rainfall, heat waves, and UV irradiation, which may be intensified by climate change. MP-DOM release varies with plastic type and conditions, with organic additives significantly influencing leaching under UV exposure. Increased turbulence from hydrological events and rising temperatures also enhances MP-DOM release. While most research has focused on specific additive releases, the broader effects of polymer degradation and subsequent impacts on microbial communities and biogeochemical cycles are only recently recognized. These disruptions may affect cellular processes in algae and plant roots, enhance microbial utilization of dissolved organic carbon, and potentially increase greenhouse gas production. Our review highlights overlooked roles of MP-DOM exacerbated by climatic stressors and calls for further research to understand its broader biogeochemical impacts. We also emphasize the importance of distinguishing between polymers and commercial plastics when assessing MP-DOM's effects on biogeochemical processes associated with carbon and nitrogen cycles and recommend investigating additional aging processes influencing MP-DOM release.

The interaction between seagrass meadow density and microplastic retention in four cool-temperate estuaries

Microplastics are widespread pollutants of estuarine ecosystems. Seagrasses have been hypothesized to filter microplastics through their dense meadows, yet the mechanisms governing their interaction with microplastics are not well understood, particularly within a South African context. Here we compared how microplastics might accumulate in the sediments associated with Zostera capensis meadows across dense and patchy meadows and unvegetated sediment. In addition, estuarine surface waters were sampled and analysed. The number of microplastics ranged between 23.5 ± 24.9 and 30.1 ± 22.1 microplastics per Kg sediment, with up to 70 % identified as fibres. In three of the four estuaries, a greater abundance of microplastics were found in areas of dense seagrass coverage compared to bare sediment, with fibres and fragments found to be the dominant microplastic. Estuarine surface waters revealed microplastic concentrations ranging from 1.7 ± 1.6 to 2.5 ± 1.4 MPs per m3, with 88 % of samples containing microplastics. This study confirms the trapping ability of Z. capensis meadows for microplastics and highlights paucity of regional knowledge into the effects that microplastics may have on seagrass health and persistence.

Analysing the influence of hydrodynamic and sedimentary factors on the microplastic distribution in the Ashtamudi estuary, India

This study evaluates the influence of water current and suspended sediment concentration (SSC) on microplastic distribution in various mixing regimes of the Ashtamudi estuary, India. Microplastic abundance ranged from 3.2 to 53 items/L, with highest concentrations observed near the confluence of the river and the sea. Partially mixed regions exhibited elevated near-bottom microplastic concentrations, identifying these zones as potential settling areas. Microplastic abundance showed a direct relationship with SSC and an inverse relationship with current. A non-linear model developed to predict microplastic abundance based on SSC and current demonstrated good performance, achieving an R2 value of 0.97. This model outperformed the SSC-only model, representing a significant advancement over previous studies. The findings highlight the critical roles of hydrodynamic and sedimentary factors in governing microplastic distribution within the water column. The developed model, after calibration, can be applied to other estuaries globally, supporting plastic monitoring programmes in implementing effective mitigation measures.

Microplastics in marine fish: a mini-review on presence, classification, and impacts

Plastic production has experienced exponential growth in recent years due to its diverse industrial applications, low cost, and high availability, also causing issues, since plastic waste in aquatic ecosystems transforms into microplastics (MPs) through mechanical and weathering processes. Microplastics are distributed ubiquitously in water bodies, where they can be ingested by a wide aquatic organism range, including fish, which have been used as bioindicators to assess microplastic presence and toxicity. Research has revealed microplastic presence in various fish species worldwide; the most common characteristics are fibers and fragments of blue, black, and transparent colors, and polyethylene, terephthalate, polypropylene and cellophane chemical composition. Experimental studies under laboratory conditions have demonstrated microplastics impact on fish, showing physical, immunological, and hematological damage, and oxidative stress ultimately leading to organisms' death. However, laboratory results do not necessarily predict impacts on wild fish due to different conditions to which the organisms are exposed. Therefore, further research needs to simulate real scenarios faced by wild fish in the marine environment, providing greater certainty about microplastic impacts and negative effects.

Assessment of microplastics and associated ecological risk in the longest river (Godavari) of peninsular India: A comprehensive source-to-sink analysis in water, sediment and fish

Persistent microplastics (MPs) accumulation in the aqueous environments is considered a threat to the ecosystem, potentially harming aquatic species and human health. In view of the escalating problem of MPs pollution in India, a comprehensive investigation of MPs accumulation in major riverine systems is necessary. The current study aims to estimate MPs abundance in surface water, sediment, and fish samples along the entire stretch of Godavari, the largest river in peninsular India. Average MPs concentrations in water lie in the range of 311-939 MPs/m3 and 2-144 MPs/kg d.w. for sediment. Urban regions and dam reservoirs showed elevated MPs abundance, emphasizing the impact of anthropogenic activities. The μ-Raman analysis revealed PE and PP were the abundantly occurring polymers in all matrices. Polymer and ecological risk index identify most sampling sites as extremely high-risk zones, posing a potential threat to aquatic ecosystems and human health. Plotted t-SNE (t-distributed Stochastic Neighbour Embedding) revealed similarities in MPs morphology and compositions among water, sediment and fish samples. Examined MPs in edible (flesh+skin) and inedible parts (GIT and gills) of seven different fish species showed a higher average MPs abundance in edible parts (10.7 ± 14.9 MPs/fish) than gills (7 ± 8.1 MPs/fish) and GIT (6.6 ± 5.5 MPs/fish). This suggests that removing gills and GIT from fish doesn't eliminate the consumer's risk of MPs intake. Overall, our work highlights the significant MPs pollution in the Godavari River, further providing essential data on the ecological risk of MPs to guide municipal action plans, improve waste management, target high-risk areas, and raise awareness to mitigate impacts.

Could Mussel Populations Be Differentially Threatened by the Presence of Microplastics and Related Chemicals?

Mussels serve as indicators of anthropogenic chemical pollution; however, the effects of microplastics and plastic-related chemicals on their health performance remain an emerging issue. In this study, mussels were exposed to a polyamide (PA; 5 μg/L) and tricresyl phosphate (TCP; 1 μg/L) for 28 days. The exposures to the two contaminants were performed independently or in combination and lasted 28 days. The results showed that the independent exposure altered enzyme activities more significantly than the combined one. Exposure to the PA significantly (p < 0.05) inhibited the antioxidant enzyme catalase (CAT) by 43.5% and the neurotransmitter enzyme acetylcholinesterase (AChE) by 40.6%, while TCP specifically inhibited carboxylesterase (CE) activity by 38.5%, all in respect to the solvent control. When both pollutants were combined, most biomarker responses were similar to control levels. To further investigate if the mussels' response to contaminants (here, chemical compounds only) could be population-specific, a comparative study between Atlantic and Mediterranean mussels was included. Firstly, baseline detoxification defenses were contrasted in the digestive glands of each mussel population, followed by an assessment of in vitro responses to a wide range of plastic additives. The results revealed that Mediterranean mussels expressed higher baseline activities for most detoxification enzymes, although the in vitro sensitivity to the targeted chemicals was similar in both populations. Of all the plastic additives tested, TCP significantly inhibited CE activity both in vivo and in vitro. The in vitro screening also indicated that other plastic additives could act as strong inhibitors of CE. However, additional in vivo exposures in mussels are needed to confirm CE suitability as a biomarker of these chemical exposures. All together, these results also suggest critical population-level differences in susceptibility to microplastic pollution, highlighting a need for targeted conservation efforts.

Evaluating Toxic Interactions of Polystyrene Microplastics with Hazardous and Noxious Substances Using the Early Life Stages of the Marine Bivalve Crassostrea gigas

Plastics pose a significant threat to marine ecosystems, owing to their slow biodegradability. Microplastics (MPs), in particular, affect marine life and maricultural organisms and can enter the food chain via ingestion by marine organisms, leading to bioaccumulation in predators, including humans. This study assessed the toxic interactions between polystyrene microplastic particles (PSMPs) and cadmium (Cd) and phenanthrene (Phe) using marine bivalves. While PSMPs were non-toxic to Pacific oysters (Crassostrea gigas), the toxicity of Cd and Phe was concentration-dependent. In most conditions, PSMPs reduced the toxicity of Cd and Phe, but in simultaneous exposure, they acted as Cd messengers, altering the toxicity during the adult stage. This study confirms that PSMPs can interact with coastal environmental pollutants, thereby accelerating biotoxicity and posing a significant threat to marine wildlife, mariculture, and human health. It also highlights the need to assess MP toxicity in coastal environments and their interactions with pollutants.

Primary astrocytes as a cellular depot of polystyrene nanoparticles

The continuous increase in plastic production has resulted in increased generation of microplastic particles (MPs), and nanoplastic particles (NPs). Recent evidence suggests that nanoplastics may be a potent neurotoxin because they are able to freely cross the blood-brain barrier and enter the brain. Therefore, the cytotoxic effects of polystyrene nanoparticles (PS-NPs) on cellular systems of cerebral origin should be thoroughly investigated. The aim of the current study is to evaluate the cytotoxic potential of 25 nm PS-NPs on in vitro cultured cells such as primary astrocytes, neurons and their co-cultures established from the cerebral cortex of Wistar pups. The results show that PS-NPs are internalized in both neurons and astrocytes, inducing time- and concentration-dependent cytotoxic effects. However, quantification of fluorescence intensity indicates cell type-dependent differences in the efficiency of PS-NPs uptake. Astrocytes are several times more efficient at accumulating PS-NPs than neurons, and this is a phagocytosis-dependent process. Moreover, the high rate of PS-NPs internalization during prolonged exposure (72 h) promotes astroglial activation, as assessed by analysis of GFAP expression and immunocytochemical imaging. The results show that astroglia act as a cellular depot of PS-NPs to protect neurons. However, once the critical threshold is exceeded, astroglia become overactivated and can lose their protective functions. These results highlight the importance of further research on the mechanisms underlying nanoplastic-induced cellular toxicity, which may have implications for understanding the broader impact of plastic pollution on neurological functions.

Microplastics in Mussels (Mytilus galloprovincialis): Understanding Pollution in Italian Seas

Plastic marine litter is a critical issue that threatens marine ecosystems. This study investigated microplastics (MPs) contamination in the Italian seas, involving regions significantly affected by pollution from urban, industrial and agricultural sources. The research, conducted in collaborations between 10 different Experimental Zooprophylactic Institutes throughout Italy, analyzed Mytilus galloprovincialis (common mussels) for its filtration capacity and suitability as a bioindicator. Using data from two projects funded by the Italian Ministry of Health, MPs were detected from 7% to 13% of mussel samples, mainly polypropylene and polystyrene fragments and fibers. These findings align with previous studies highlighting the pervasive presence of MPs and their potential risks as mussels are consumed whole, allowing MPs to be ingested. The study underscores the need for standardized detection methods and coordinated policies to mitigate plastic pollution. Public awareness campaigns and improved waste management practices are key to addressing the environmental and health impacts of MPs. Further research on the long-term effects of MPs on marine ecosystems and human health is essential to developing comprehensive mitigation strategies.

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.

A preliminary assessment of microplastics in the waters and sediments of the second-largest freshwater lagoon in India

Pulicat is India's second-largest freshwater lagoon having unique biological ecosystem and economical importance. The lagoon systems are highly polluted by the microplastics (MP) due to anthropogenic activity and microplastics are highly emerging kind of contaminant in the environment. Samples were collected from a part of the lagoon near the mouth region. Morphological identification of microplastics with microscope and polymer identification using ATR-FTIR and Micro-Raman spectroscopy was carried out. From the result, average abundance of the MP particles in surface water ranges 3.12 ± 1.53 particles per 1000 l and 701 ± 198 particles per kg for sediments, respectively. Microplastics < 1 mm (1-1000 microns) are dominant in size. Fibres, fragments and films were most occupied in physical form, respectively, in microplastic samples and polypropylene (PP) and polyethylene (PE) were the predominant polymer types composited in MP particles. This study concludes that Pulicat lagoon is significantly polluted by microplastic, which is mostly contributed by fishing and mismanagement of plastic wastes.

Unveiling microbial succession dynamics on different plastic surfaces using WGCNA

Over recent decades, marine microorganisms have increasingly adapted to plastic debris, forming distinct plastic-attached microbial communities. Despite this, the colonization and succession processes on plastic surfaces in marine environments remain poorly understood. To address this knowledge gap, we conducted a microbiome succession experiment using four common plastic polymers (PE, PP, PS, and PET), as well as glass and wood, in a temperature-controlled seawater system over a 2- to 90-day period. We employed long-read 16S rRNA metabarcoding to profile the prokaryotic microbiome's taxonomic composition at five time points throughout the experiment. By applying Weighted Gene Co-expression Network Analysis (WGCNA) to our 16S metabarcoding data, we identified unique succession signatures for 77 bacterial genera and observed polymer-specific enrichment in 39 genera. Our findings also revealed that the most significant variations in microbiome composition across surfaces occurred during the initial succession stages, with potential intra-genus relationships that are linked to surface preferences. This research advances our understanding of microbial succession dynamics on marine plastic debris and introduces a robust statistical approach for identifying succession signatures of specific bacterial taxa.

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

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

Integrating C-H Information to Improve Machine Learning Classification Models for Microplastic Identification from Raman Spectra

Research has shown microplastic particles to be pervasive pollutants in the natural environment, but labor-intensive sample preparation, data acquisition, and analysis protocols continue to be necessary to navigate their diverse chemistry. Machine learning (ML) classification models have shown promise for identifying microplastics from their Raman spectra, but all attempts to date have focused on the lower energy "fingerprint" region of the spectrum. We explore strategies to improve ML classification models based on the k-nearest-neighbor algorithm by including other regions of the Raman spectra. The information content inherent in C-H bonds, which occur in the higher frequency region of 2500-3600 cm-1, is found to be particularly powerful in improving classification model performance. Variations in the relative intensity of peaks arising from C-H vibrations improve identification capabilities for plastics that the fingerprint region alone struggles with, such as resolving acrylonitrile butadiene styrene from polystyrene and identifying poly(vinyl chloride), polyurethane, and polyoxymethylene. Testing of strategies to both acquire and analyze data across the two regions is explored for their efficacy and their compatibility with real-world sampling restrictions. We find that localized normalization of spectra, independently acquired in the two regions, provides the most direct and effective route to improving the ML classification performance.