Microplastic abundance, distribution and composition in the mid-west Pacific Ocean

Microplastic concentration, characterization, and size distribution in the Delaware Bay estuary

Microplastic (MP) pollution has been widely reported across water matrices including in estuaries, which are important for the understanding of oceanic MPs. Estuaries can greatly alter the fate, transport, size distribution, and abundance of plastic pollution. The aim of this study was to quantify and characterize MP pollution in the Delaware Bay estuary USA, including the size distribution. Samples (N = 31) were collected from the mouth of the Delaware River to the coastal ocean including multiple frontal zones across two sampling campaigns (2019 and 2022). MP were extracted from the collected particles using wet peroxide oxidation and density separation with saturated sodium chloride. Particles collected on 500 μm mesh sieves were analyzed via Fourier transform infrared (FTIR) spectroscopy. Across all samples, 324 of the 1015 particles analyzed were MP, and 11 macroplastics were observed. MP concentrations ranged from below detection to 4.12 MP/m3 (mean 0.34 ± 0.80 MP/m3). No significant differences were observed between sampling sites; nonetheless, the two highest MP concentrations were observed when sampling along frontal zones with visible debris including macroplastics. Polyethylene (53%) and polypropylene (43%) were the most abundant polymers observed. The majority of the non-plastic particles were classified as particulate natural organic matter (82% of non-plastics). Particles from samples collected during 2022 (N = 864) also had color, morphology, and two size dimensions recorded. MP particle size was significantly associated with sampling site, with the coastal ocean sampling site generally having the smallest MPs. A correlation between total post-extraction particles and total plastic particles was observed. Aspect ratios for the plastics ranged from one to 40.7, with larger ratios for fibers, with a mean (±standard deviation) of 3.39 ± 4.72 (unitless). These aspect ratios can be used to select shape factors used to estimate the total volume of MP in the studied size range. Overall, these results can help inform fate, transport, and risk assessments related to estuarine plastic pollution.

Toxic effects of fragmented polyethylene terephthalate particles on the marine rotifer Brachionus koreanus: Based on ingestion and egestion assay, in vivo toxicity test, and multi-omics analysis

Microplastics (MPs) are a major concern in marine ecosystem because MPs are persistent and ubiquitous in oceans and are easily consumed by marine biota. Although many studies have reported the toxicity of MPs to marine biota, the toxicity of environmentally relevant types of MPs is little understood. We investigated the toxic effects of fragmented polyethylene terephthalate (PET) MP, one of the most abundant MPs in the ocean, on the marine rotifer Brachionus koreanus at the individual and molecular level. No significant rotifer mortality was observed after exposure to PET MPs for 24 and 48 h. The ingestion and egestion assays showed that rotifers readily ingested PET MPs in the absence of food but not when food was supplied; thus, there were also no chronic effects of PET MPs. In contrast, intracellular reactive oxygen species levels and glutathione S-transferase activity in rotifers were significantly increased by PET MPs. Transcriptomic and metabolomic analyses revealed that genes and metabolites related to energy metabolism and immune processes were significantly affected by PET MPs in a concentration-dependent manner. Although acute toxicity of PET MPs was not observed, PET MPs are potentially toxic to the antioxidant system, immune system, and energy metabolism in rotifers.

Viability of elutriation for the extraction of microplastics from environmental soil samples

In this study, we evaluated the suitability of elutriation, a method successfully employed in the extraction of microplastics from marine sediments, for the extraction of microplastics from freshwater and terrestrial soils. Five soils were sampled throughout Oklahoma, USA in order to capture a range of sand, silt, clay, and organic matter composition. Each soil was subjected to microplastic extraction with and without elutriation, followed by digestion in 7.5% NaOCl, and then flotation in 6 M ZnCl2. The mass of each soil was measured after elutriation to determine sample mass reduction, and multiple methods including fluorescence imaging and automated particle counting through ImageJ, Attenuated Total Reflectence-Fourier Transfor Infrared Spectroscopy (ATR-FTIR), and Pyrolysis-coupled Gas Chromatography/Mass Spectrometry (py-GC/MS) were used to determine microplastic quantity, mass, and characteristics. T-test was used to check for statistically-significant differences between methods in terms of mass or particle quantity. For all tested soils, elutriation resulted in greater sample mass reduction than non-elutriated samples, and was between 59.0-97.3% for the tested soils. Furthermore, no statistically significant (p < 0.05) differences were observed in particle quantification or polymer mass between methods, and no differences were observed for polymer or size distribution. Additionally, 33% more polymers were positively identified (R 2 = 70%) by ATR-FTIR analysis in elutriated samples compared to non-elutriated soils. The mass reduction provided by elutriation allows for the processing of larger sample volumes, leading to greater accuracy and sensitivity in detecting microplastics. As such, we recommend elutriation be performed as a pretreatment step to extract microplastics from soils.

Electrochemically microplastic detection using chitosan-magnesium oxide nanosheet

Microplastics, an invisible threat, are emerging as serious pollutants that continuously affect health by interrupting/contaminating the human cycle, mainly involving food, water, and air. Such serious scenarios raised the demand for developing efficient sensing systems to detect them at an early stage efficiently and selectively. In this direction, the proposed research reports an electrochemical hexamethylenetetramine (HMT) sensing utilizing a sensing platform fabricated using chitosan-magnesium oxide nanosheets (CHIT-MgO NS) nanocomposite. HMT is considered as a hazardous microplastic, which is used as an additive in plastic manufacturers and has been selected as a target analyte. To fabricate sensing electrodes, a facile co-precipitation technique was employed to synthesize MgO NS, which was further mixed with 1% CHIT solution to form a CHIT_MgO NS composite. Such prepared nanocomposite solution was then drop casted to an indium tin oxide (ITO) to fabricate CHIT_MgO NS/ITO sensing electrode to detect HMT electrochemically using cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques. To determine the limit of detection (LOD) and sensitivity, DPV was performed. The resulting calibrated curve for HMT, ranging from 0.5 μM to 4.0 μM, exhibited a sensitivity of 12.908 μA (μM)-1 cm-2 with a detection limit of 0.03 μM and a limit of quantitation (LOQ) of 0.10 μM. Further, the CHIT_MgO NS/ITO modified electrode was applied to analyze HMT in various real samples, including river water, drain water, packaged water, and tertiary processed food. The results demonstrated the method's high sensitivity and suggested its potential applications in the field of microplastic surveillance, with a focus on health management.

Occurrence, potential sources, and ecological risk assessment of microplastics in the inland river basins in Northern China

Microplastics (MPs) are the pollutants, found widely across various environmental media. However, studies on the MP pollution in urban rivers and the necessary risk assessments remain limited. In this study, the abundance and characteristics of microplastics in a typical urban river were examined to evaluate their distribution, sources, and ecological risks. It was observed that the abundance of MPs in sediments (220-2840 items·kg-1 dry weight (DW)) was much higher than that in surface water (2.9-10.3 items·L-1), indicating that the sediment is the "sink" of river MPs. Surface water and sediment were dominated by small particle size MPs (< 0.5 mm). Fiber and debris were common shapes of MPs in rivers and sediments. The microplastics in river water and sediments were primarily white and transparent, respectively. Polypropylene (PP) and polyethylene (PE) were the major polymers found.

Micro-and nano-plastics induce kidney damage and suppression of innate immune function in zebrafish (Danio rerio) larvae

Aquatic environments serve as critical repositories for pollutants and have significantly accumulated micro- and nanoplastics (MNPs) due to the extensive production and application of plastic products. While the disease resistance and immunity of fish are closely linked to the condition of their aquatic habitats, the specific effects of nanoplastics (NPs) and microplastics (MPs) within these environments on fish immune functions are still not fully understood. The present study utilized zebrafish (Danio rerio) embryos and larvae as model organisms to examine the impacts of polystyrene NPs (100 nm) and MPs (5 μm) on fish immune responses. Our findings reveal that NPs and MPs tend to accumulate on the surfaces of embryos and within the intestines of larvae, triggering oxidative stress and significantly increasing susceptibility to Edwardsiella piscicida infection in zebrafish larvae. Transmission electron microscopy examined that both NPs and MPs inflicted damage to the kidney, an essential immune organ, with NPs predominantly inducing endoplasmic reticulum stress and MPs causing lipid accumulation. Transcriptomic analysis further demonstrated that both NPs and MPs significantly suppress the expression of key innate immune pathways, notably the C-type lectin receptor signaling pathway and the cytosolic DNA-sensing pathway. Within these pathways, the immune factor interleukin-1 beta (il1b) was consistently downregulated in both exposure groups. Furthermore, exposure to E. piscicida resulted in restricted upregulation of il1b mRNA and protein levels, likely contributing to diminished disease resistance in zebrafish larvae exposed to MNPs. Our findings suggest that NPs and MPs similarly impair the innate immune function of zebrafish larvae and weaken their disease resistance, highlighting the significant environmental threat posed by these pollutants.

Emerging pollutant in surface water bodies: a review on monitoring, analysis, mitigation measures and removal technologies of micro-plastics

Water bodies play a crucial role in supporting life, maintaining the environment, and preserving the ecology for the people of India. However, in recent decades, human activities have led to various alterations in aquatic environments, resulting in environmental degradation through pollution. The safety of utilizing surface water sources for drinking and other purposes has come under intense scrutiny due to rapid population growth and industrial expansion. Surface water pollution due to micro-plastics (MPs) (plastics < 5 mm in size) is one of the emerging pollutants in metropolitan cities of developing countries because of its utmost resilience and synthetic nature. Recent studies on the surface water bodies (river, pond, Lake etc.) portrait the correlation between the MPs level with different parameters of pollution such as specific conductivity, total phosphate, and biological oxygen demand. Fibers represent the predominant form of MPs discovered in surface water bodies, exhibiting fluctuations across seasons. Consequently, present study prioritizes understanding the adaptation, prevalence, attributes, fluctuations, and spatial dispersion of MPs in both sediment and surface water environments. Furthermore, the study aims to identify existing gaps in the current understanding and underscore opportunities for future investigation. From the present study, it has been reported that, the concentration of MPs in the range of 0.2-45.2 items/L at the Xisha Islands in the south China sea, whereas in India it was found in the range of 96 items/L in water samples and 259 items/kg in sediment samples. This would certainly assist the urban planners in achieving sustainable development goals to mitigate the increasing amount of emergent pollutant load.

Microplastics in multi-environmental compartments: Research advances, media, and global management scenarios

During the past decades, microplastics (MPs) have become an emerging concern due to their persistence and potential environmental threat. MP pollution has become so drastic that it has been found in the human food chain, breast milk, polar regions, and even the Himalayan basin, lake, etc. Inflammation, pulmonary hypertension, vascular occlusions, increased coagulability and blood cell cytotoxicity, disruption of immune function, neurotoxicity, and neurodegenerative diseases can all be brought on by severe microplastic exposure. Although many MPs studies have been performed on single environmental compartments, MPs in multi-environmental compartments have yet to be explored fully. This review aims to summarize the muti-environmental media, detection tools, and global management scenarios of MPs. The study revealed that MPs could significantly alter C flow through the soil-plant system, the structure and metabolic status of the microbial community, soil pH value, biomass of plant shoots and roots, chlorophyll, leaf C and N contents, and root N contents. This review reveals that MPs may negatively affect many C-dependent soil functions. Different methods have been developed to detect the MPs from these various environmental sources, including microscopic observation, density separation, Raman, and FT-IR analysis. Several articles have focused on MPs in individual environmental sources with a developed evaluation technique. This review revealed the extensive impacts of MPs on soil-plant systems, microbial communities, and soil functions, especially on water, suggesting possible disturbances to vital ecological processes. Furthermore, the broad range of detection methods explored emphasizes the significance of reliable analytical techniques in precisely evaluating levels of MP contamination in various environmental media. This paper critically discusses MPs' sources, occurrences, and global management scenarios in all possible environmental media and ecological health impacts. Future research opportunities and required sustainable strategies have also been suggested from Bangladesh and international perspectives based on challenges faced due to MP's pollution.

Enhancing the coagulation process for the removal of microplastics from water by anionic polyacrylamide and natural-based Moringaoleifera

The existence of microplastics (MPs) in water is a significant global concern since they have the potential to pose a threat to human health. Therefore, there is a need to develop a sustainable treatment technology for MPs removal, as the conventional methods are inadequate to address this problem. Coagulation is a typical process in treatment plants that can capture MPs before releasing them into the environment. In this work, the removal behaviors of polyamide (PA), polystyrene (PS), and polyethylene (PE) MPs were systematically investigated through coagulation processes using aluminum sulfate (Al2(SO4)3) and Moringa oleifera (MO) seeds extract. Subsequently, the coagulation performance of Al2(SO4)3 was improved by the separate addition of anionic polyacrylamide (APAM) and naturally derived MO. Results showed that Al2(SO4)3 in combination with APAM had better performance than Al2(SO4)3 or MO alone. In the Al2(SO4)3+APAM system, the removal efficiencies were 93.47%, 81.25%, and 29.48% for PA, PS, and PE MPs, respectively. Furthermore, the effectiveness of the Al2(SO4)3 and MO blended system was approximately similar to the Al2(SO4)3+APAM system. However, the required amount of Al2(SO4)3 was decreased to 50% in the Al2(SO4)3+MO system compared to the optimal dosage in the Al2(SO4)3 system alone. The combination of 40 mg/L of Al2(SO4)3 and 60 mg/L of MO resulted in removal efficiencies of 92.99%, 80.48%, and 28.94% for PA, PS, and PE MPs, respectively. The high efficacy of these enhanced methods was due to the synergic effects of charge neutralization and agglomeration adsorption, which were validated through zeta potential assessments and visual analysis using scanning electron microscopy (SEM) images. In the case of experimental conditions, initial pH had little impact on removal efficiency, while NaCl salinity and stirring speed directly affected MPs removal. Consequently, this research took a step toward finding a green strategy to remove MPs from water systems.

Recent advances in microplastic removal from drinking water by coagulation: Removal mechanisms and influencing factors

Microplastics (MPs) are emerging contaminants that are widely detected in drinking water and pose a potential risk to humans. Therefore, the MP removal from drinking water is a critical challenge. Recent studies have shown that MPs can be removed by coagulation. However, the coagulation removal of MPs from drinking water remains inadequately understood. Herein, the efficiency, mechanisms, and influencing factors of coagulation for removing MPs from drinking water are critically reviewed. First, the efficiency of MP removal by coagulation in drinking water treatment plants (DWTPs) and laboratories was comprehensively summarized, which indicated that coagulation plays an important role in MP removal from drinking water. The difference in removal effectiveness between the DWTPs and laboratory was mainly due to variations in treatment conditions and limitations of the detection techniques. Several dominant coagulation mechanisms for removing MPs and their research methods are thoroughly discussed. Charge neutralization is more relevant for small-sized MPs, whereas large-sized MPs are more dependent on adsorption bridging and sweeping. Furthermore, the factors influencing the efficiency of MP removal were jointly analyzed using meta-analysis and a random forest model. The meta-analysis was used to quantify the individual effects of each factor on coagulation removal efficiency by performing subgroup analysis. The random forest model quantified the relative importance of the influencing factors on removal efficiency, the results of which were ordered as follows: MPs shape > Coagulant type > Coagulant dosage > MPs concentration > MPs size > MPs type > pH. Finally, knowledge gaps and potential future directions are proposed. This review assists in the understanding of the coagulation removal of MPs, and provides novel insight into the challenges posed by MPs in drinking water.

Trophic transfer of micro- and nanoplastics and toxicity induced by long-term exposure of nanoplastics along the rotifer (Brachionus plicatilis)-marine medaka (Oryzias melastigma) food chain

Microplastics (MPs) and nanoplastics (NPs) are emerging pollutants in the ocean, but their transfer and toxicity along the food chains are unclear. In this study, a marine rotifer (Brachionus plicatilis)-marine medaka (Oryzias melastigma) food chain was constructed to evaluate the transfer of polystyrene MPs and NPs (70 nm, 500 nm, and 2 μm, 2000 μg/L) and toxicity of 70 nm PS-NPs (0, 20, 200, and 2000 μg/L) on marine medaka after long-term food chain exposure. The results showed that the amount of 70 nm NPs accumulated in marine medaka was 1.24 μg/mg, which was significantly higher than that of 500 nm NPs (0.87 μg/mg) and 2 μm MP (0.69 μg/mg). Long-term food chain exposure to NPs caused microflora dysbiosis, resulting in activation of toll-like receptor 4 (TLR4) pathway, which induced liver inflammation. Moreover, NPs food chain exposure increased liver and muscle tissue triglyceride and lactate content, but decreased the protein, sugar, and glycogen content. NPs food chain exposure impaired reproductive function and inhibited offspring early development, which might pose a threat to the sustainability of marine medaka population. Overall, the study revealed the transfer of MPs and NPs and the effects of NPs on marine medaka along the food chain.

Feasibility study of the use of concrete blocks produced from plastic marine garbage for use in civil construction

The pursuit of development in an economically sustainable and ecologically sound manner is a goal of modern society. It has been investing in products that minimize their environmental impact, particularly concerning the use of plastic. This material is highly detrimental to nature due to its toxicity and long decomposition period. The present study aims to analyze the feasibility of producing blocks made of concrete with different amounts of waste plastic taken from coastal and estuarine areas. After laboratory analysis, it was found that blocks containing 5% plastic exhibit good compressive strength and are lighter. Additionally, there was an increase in the acidity of the sample, a decrease in the density of the block, and reductions in both flexural and compressive strength. The prototype, composed of 5% plastic by mass, proves to be efficient for constructing single-story houses. It meets the minimum requirements for normative resistance, effectively encapsulating the plastic within the block and thereby reducing its environmental impact.

Microplastic-mediated new mechanism of liver damage: From the perspective of the gut-liver axis

Microplastics (MPs) are environmental contaminants that are present in all environments and can enter the human body, accumulate in various organs, and cause harm through the ingestion of food, inhalation, and dermal contact. The connection between bowel and liver disease and the interplay between gut, liver, and flora has been conceptualized as the "gut-liver axis". Microplastics can alter the structure of microbial communities in the gut and the liver can also be a target for microplastic invasion. Numerous studies have found that when MPs impair human health, they not only promote dysbiosis of the gut microbiota and disruption of the gut barrier but also cause liver damage. For this reason, the gut-liver axis provides a new perspective in understanding this toxic response. The cross-talk between MPs and the gut-liver axis has attracted the attention of the scientific community, but knowledge about whether MPs cause gut-liver interactions through the gut-liver axis is still very limited, and the effect of MPs on liver injury is not well understood. MPs can directly induce microbiota disorders and gut barrier dysfunction. As a result, harmful bacteria and metabolites in the gut enter the blood through the weak intestinal barrier (portal vein channel along the gut-liver axis) and reach the liver, causing liver damage (inflammatory damage, metabolic disorders, oxidative stress, etc.). This review provides an integrated perspective of the gut-liver axis to help conceptualize the mechanisms by which MP exposure induces gut microbiota dysbiosis and hepatic injury and highlights the connection between MPs and the gut-liver axis. Therefore, from the perspective of the gut-liver axis, targeting intestinal flora is an important way to eliminate microplastic liver damage.

Micro(nano)plastics in human urine: A surprising contrast between Chongqing's urban and rural regions

Microplastics (100 nm-5 mm) and nanoplastics (<100 nm) collectively referred to as micro(nano)plastics (MNPs), which are emerging pollutants all over the world. Environmental differences affect its distribution. The content of MNPs differs between urban and rural environments, according to previous studies. To understand the actual situation of human exposure to MNPs in various environments, this study collected 12 urine samples from volunteers in urban and rural regions of Chongqing and used pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) and laser direct infrared spectroscopy (LDIR) to detect and analyze MNPs in urine. With an average abundance of 1.50 (2.31) mg/kg, MNPs were found in 9 samples by Py-GC/MS. Polyethylene (PE), polyvinyl chloride (PVC) and polyamide 66 (PA66), three different types of MNPs were found, with PE content being the highest among them. By using LDIR, MNPs were found in 7 samples, with an average abundance of 15.17 (23.13) particles/kg. Five different types of MNPs were found, with acrylates (ACR) being the main type, followed by polymethylmethacrylate (PMMA), polyurethane (PU), polypropylene (PP), polyethylene terephthalate (PET). The findings demonstrated that urban region had much greater levels and more types of MNPs in human urine than rural. Additionally, regular contact with plastic toys and the use of personal care products are linked to the presence of MNPs. The influence of environmental factors on the actual exposure of the human body to MNPs was preliminary explored in this study, and two different methods were used for the first time to simultaneously detect and analyze MNPs in human urine. This allowed for the feasibility of comprehensively and effectively quantitatively analyzing the actual exposure of the human body to MNPs, and also provided the theoretical foundation for further research on the harm of MNPs to human health in different environments.

Development of a multi-spectroscopy method coupling μ-FTIR and μ-Raman analysis for one-stop detection of microplastics in environmental and biological samples

Current techniques for microplastics (MPs) analysis are diverse. However, most techniques have individual limitations like the detection limit of spatial resolution, susceptibility, high cost, and time-consuming detection. In this study, we proposed a multi-spectroscopy method coupling μ-FTIR and μ-Raman analysis for one-stop MPs detection, in which barium fluoride was used as the substrate alternative to the filter membrane. Compared with commonly used filter membranes (alumina, silver, PTFE and nylon membranes), the barium fluoride substrate showed better spectroscopic detection performance on microscopic observation, broader transmittable wavenumber range for μ-FTIR (750-4000 cm-1) and μ-Raman (250-4000 cm-1) detection, thus suitable for the multi-spectroscopy analysis of spiked samples. Further, the real environmental and biological samples (indoor air, bottled water and human exhaled breath) were collected and detected to verify the applicability of the developed multi-spectroscopy method. The results indicated that the average content of detected MPs could be increased by 30.4 ± 29.9 % for indoor air, 17.1 ± 13.2 % for bottled water and 38.4 ± 16.0 % for human exhaled breath, respectively in comparison with widely used μ-Raman detection, which suggested that MPs exposure might be underestimated using single spectroscopy detection. Moreover, the majority of underestimated MPs were colored and smaller sized (<50 μm) MPs, which could pose higher risks to human body. In addition, the proposed method consumed lower sample pre-treatment costs and was environmental-friendly since the barium fluoride substrate could be used repeatedly after being cleaned by organic solvent with reliable results (n = 10, CV = 10 %, ICC = 0.961), which reduced the cost of MPs detection by at least 2.49 times compared with traditional methods using silver membrane.

Microplastics and Nanoplastics in Atheromas and Cardiovascular Events

BACKGROUND

Microplastics and nanoplastics (MNPs) are emerging as a potential risk factor for cardiovascular disease in preclinical studies. Direct evidence that this risk extends to humans is lacking.

METHODS

We conducted a prospective, multicenter, observational study involving patients who were undergoing carotid endarterectomy for asymptomatic carotid artery disease. The excised carotid plaque specimens were analyzed for the presence of MNPs with the use of pyrolysis-gas chromatography-mass spectrometry, stable isotope analysis, and electron microscopy. Inflammatory biomarkers were assessed with enzyme-linked immunosorbent assay and immunohistochemical assay. The primary end point was a composite of myocardial infarction, stroke, or death from any cause among patients who had evidence of MNPs in plaque as compared with patients with plaque that showed no evidence of MNPs.

RESULTS

A total of 304 patients were enrolled in the study, and 257 completed a mean (±SD) follow-up of 33.7±6.9 months. Polyethylene was detected in carotid artery plaque of 150 patients (58.4%), with a mean level of 21.7±24.5 μg per milligram of plaque; 31 patients (12.1%) also had measurable amounts of polyvinyl chloride, with a mean level of 5.2±2.4 μg per milligram of plaque. Electron microscopy revealed visible, jagged-edged foreign particles among plaque macrophages and scattered in the external debris. Radiographic examination showed that some of these particles included chlorine. Patients in whom MNPs were detected within the atheroma were at higher risk for a primary end-point event than those in whom these substances were not detected (hazard ratio, 4.53; 95% confidence interval, 2.00 to 10.27; P<0.001).

CONCLUSIONS

In this study, patients with carotid artery plaque in which MNPs were detected had a higher risk of a composite of myocardial infarction, stroke, or death from any cause at 34 months of follow-up than those in whom MNPs were not detected. (Funded by Programmi di Ricerca Scientifica di Rilevante Interesse Nazionale and others; ClinicalTrials.gov number, NCT05900947.).

Coagulation performance and mechanism of different hydrolyzed aluminum species for the removal of composite pollutants of polyethylene and humic acid

Microplastics (MPs) and natural organic matter (NOM) composite pollutants have become emerging contaminants with potential threats. Coagulation has been widely used to remove MPs and NOM, but the underlying mechanisms for the removal of MPs-NOM composite pollutants by hydrolyzed Al species remain unclear. Therefore, the coagulation performance and mechanism of AlCl3, polyaluminum chloride with basicity of 2.2 (PAC22), and PAC25 in treating polyethylene (PE), humic acid (HA), and PE-HA composite systems were systematically investigated. The results showed that in the single PE system, PAC25 with hexagonal clusters achieved the maximum removal (68.09 %) (pH: 5, dosage: 0.5 mM) since adsorption bridging and sweeping effect were the main mechanisms for PE removal. The adsorption of HA on the PE surface enhanced its hydrophilicity and electrostatic repulsion, resulting in decreased PE removal. In the AlCl3-PE-HA system, the oligomeric Al first interacted with the -COOH and C-OH of HA through complexation, followed by the meso- and polymers of Al interacted with PE by electrostatic adsorption. The pre-formed medium polymeric Al species (Alb) and colloidal or solid Al species (Alc) in PAC22 and PAC25 formed complexes with the -OH and -COOH groups of HA, respectively, and then removed PE by adsorption bridging and sweeping effect.

Identification and physico-chemical characterization of microplastics in marine aerosols over the northeast Arabian Sea

Microplastics (MPs) in the atmosphere can undergo long-range transport from emission regions to pristine terrestrial and oceanic ecosystems. Due to their inherent toxic and hazardous characteristics, MPs pose serious risks to both human well-being and the equilibrium of ecosystem. The present study outlines the comprehensive characterization, spanning physical and chemical attributes of MPs associated with atmospheric aerosols. Total suspended particulates (TSPs) were collected on a quartz fibre filter by operating a high-volume sampler for 24 h during distinct years (March, 2016 and November, 2020) at a coastal location in the northeast Arabian Sea. Subsequent to the sampling, a series of techniques were applied including density separation. The assessment and scrutiny of the MPs was carried out using stereo-zoom microscopy with supplementary validation using advanced fluorescence microscopy for enhanced precision in identification. Our comparative assessment suggests peroxide treatment followed by density separation could be a robust procedure for the definitive identification and characterization of MPs in the atmosphere. Average total abundance of MPs was found to be 1.30 ± 0.14 n/m3 in 2016 and 1.46 ± 0.12 n/m3 in 2020 with fibres, fragments and films having similar relative contributions (41 %, 31 %, 28 % in 2016 and 40 %, 35 %, 25 % in 2020). Fibres were found to be dominant morphotype followed by fragments and films over the coastal region of the Arabian Sea. In order to unravel the detailed chemical nature of these MPs, spectral analysis using μ-FTIR was carried out. The outcome of the analysis showed prevailing polymers as polyvinyl chloride and polymethyl methacrylate (50545 %) as dominant polymers followed by polyester (15 %), styrene butyl methacrylate (11 %), and polyacetal (9 %). MPs present in the vicinity of the Arabian Sea have potential to supply nutrients and toxicants, consequently can contribute to the modulation of the surface water biogeochemical processes.

Quantification and characterization of airborne microplastics in the coastal area of Terengganu, Malaysia

Microplastics (MPs) pose a threat to ecosystems due to their capacity to bind with toxic chemicals. While the occurrence of MPs in aquatic environmental matrices like water, sediments, and biota is well studied, their presence in the atmosphere remains less understood. This study aimed to determine the presence of airborne MPs and their characteristics through ground-based sampling in the coastal city of Kuala Nerus, Terengganu, Malaysia. Airborne MP samples were collected using passive sampling technique in December 2019. MPs were manually counted and identified using a stereomicroscope based on their colour and shape. The average deposition rate of airborne MPs during the sampling period was 5476 ± 3796 particles/m2/day, ranging from 576 to 15,562 particles/m2/day. Various colours such as transparent (38%), blue (25%), black (20%), red (13%), and others (4%) were observed. The predominant shape of airborne MPs was fibres (> 99%). The morphology structure of MPs observed using a scanning electron microscope (SEM) showed a cracked surface on MPs, suggesting weathering and irregular fragmentation. Further elemental analysis using energy dispersive X-ray spectroscopy (EDS) showed the presence of heavy metals such as aluminium (Al) and cadmium (Cd) on the surface of MPs, attributed to the adsorption capacities of MPs. Polymer types of airborne MPs were analysed using attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), which revealed particles composed of polyester (PES), polyethylene (PE), and polypropylene (PP). The preliminary findings could provide additional information for further investigations of MPs, especially in the atmosphere, to better understand their sources and potential human exposure.

Indirect daylight oxidative degradation of polyethylene microplastics by a bio-waste modified TiO2-based material

Microplastics are recognized as an emerging critical issue for the environment. Here an innovative chemical approach for the treatment of microplastics is proposed, based on an oxidative process that does not require any direct energy source (irradiation or heat). Linear low-density polyethylene (LLDPE) was selected as target commodity polymer, due to its widespread use, chemical inertness and inefficient recycling. This route is based on a hybrid material coupling titanium oxide with a bio-waste, rosin, mainly constituted by abietic acid, through a simple sol-gel synthesis procedure. The ligand-to-metal charge transfer complexes formed between rosin and Ti4+ allow the generation of reactive oxygen species without UV irradiation for its activation. In agreement with theorical calculations, superoxide radical ions are stabilized at ambient conditions on the surface of the hybrid TiO2. Consequently, an impressive degradation of LLDPE is observed after 1 month exposure in a batch configuration under indirect daylight, as evidenced by the products revealed by gas chromatography-mass spectrometry analysis and by chemical and structural modifications of the polymer surface. In a context of waste exploitation, this innovative and sustainable approach represents a promising cost-effective strategy for the oxidative degradation of microplastics, without producing any toxic by-products.

Differential impact of planktonic and periphytic diatoms on aggregation and sinking of microplastics in a simulated marine environment

Aggregation between microalgae and microplastics (MPs) significantly influences the MPs distribution in marine environment. We investigated the effects of two diatoms, the planktonic Pseudo-nitzschia pungens and the periphytic Navicula sp., on the formation and sinking of aggregates when they were cultured with four different types of MPs: small and large polyethylene terephthalate (PET) fibers, and low-density and high-density polyethylene (PE) spheres. Navicula sp. formed aggregates with all MPs within one week, but P. pungens only formed aggregates with PE spheres after 9 weeks. The PE-Navicula sp. aggregates settled about 100 times faster than the PE-P. pungens aggregates (12.2 vs. 0.1 mm s-1), and this difference was most likely due to aggregate shape rather than size. Our findings indicate that the periphytic Navicula sp. had a greater effect on the settling of MPs than the planktonic P. pungens. These findings have implications for understanding the behavior of MPs in marine environments.

Vertical distribution of microplastic along the main gate of Indonesian Throughflow pathways

Even though Pacific - Indian Ocean exchange [Indonesian Throughflow (ITF)] has been measured for the last three decades, the measurements of microplastic in the region is very limited. This study was the initial investigation of the vertical distribution of microplastic in the deep-sea areas across the ITF Pathway. Niskin water samples were utilized to obtain the samples from a water column in a range of 5 to 2450 m. A total of 924 microplastic particles with an average abundance of 1.062 ± 0.646. n/L were found in the water column. Our findings indicate that water temperature and water density are the most significant factors correlated to the microplastic concentration. This study will be the first report discussing the distribution of microplastics in the deep-sea water column that could be highly significant in determining the fate and transport of microplastic within Indonesian waters that exits into the Indian Ocean.

Microplastic particles in river sediments and water of southwestern Nigeria: insights on the occurrence, seasonal distribution, composition, and source apportionment

Microplastics (MPs) are globally recognized as an emerging environmental threat, particularly in the aquatic environment. This study presents baseline data on the occurrence and distribution of MPs in sediments and surface water of major rivers in southwestern Nigeria. Microplastics were extracted by density separation and polymer identification using Fourier transformed infrared spectroscopy in attenuated total reflectance mode (FTIR-ATR). The abundance of MPs in surface sediment and water samples across all locations ranged from 12.82 to 22.90 particle/kg dw and 6.71 to 17.12 particle/L during the dry season and 5.69 to 14.38 particle/kg dw and 12.41 to 22.73 particle/L during the wet season, respectively. On average, fiber constituted the highest percentage of MP in sediments (71%) and water (67%) while foam accounted for the lowest values of 0.6% and 1.7%, respectively. Polypropylene (PP) and polyethylene (PE) were the main MPs across all locations based on Fourier transform infrared spectroscopy (FTIR). MPs of size < 1 mm were the most abundant (≥ 55%) on average in both water and sediments. The study identified run-off from human activities and industrial wastewater as potential sources of MP exposure based on positive matrix factorization. The study suggests assessing the impact of different land-use activities on MPs occurrence and distribution in addition to quantifying MPs in seafood as a way forward in food safety management systems for further studies. This study confirmed the occurrence and widespread distribution of MPs in surface water and sediments and provides a database on MP pollution in Nigeria.

Seawater Accelerated the Aging of Polystyrene and Enhanced Its Toxic Effects on Caenorhabditis elegans

Microplastics (MPs) are emerging pollutants and pose a significant threat to marine ecosystems. Although previous studies have documented the mechanisms and toxic effects of aging MPs in various environments, the impact of the marine environment on MPs remains unclear. In the present study, the aging process of polystyrene (PS) in seawater was simulated and the changes in its physicochemical properties were investigated. Our results showed that the surface of the PS eroded in the seawater, which was accompanied by the release of aged MPs with a smaller size. In situ optical photothermal infrared microspectroscopy revealed that the mechanism of PS aging was related to the opening of the carbonyl group and breaking of the bond between carbon and benzene removal. To verify the toxic effects of aged PS, Caenorhabditis elegans was exposed to PS. Aged PS resulted in a greater reduction in locomotion, vitality, and reproduction than virgin PS. Mechanistically, aged PS led to oxidative stress, high glutathione s-transferase activity, and high total glutathione in worms. Together, our findings provided novel information regarding the accelerated aging of PS in seawater and the increased toxicity of aged PS, which could improve our understanding of MPs' ecotoxicity in the marine environment.

Microplastic enrichment capacity of Ctenochaetus striatus from the habitat environment - An example in Xisha, South China Sea

Microplastic pollution is a widespread concern in the global marine environment. In this study, microplastic pollution status in Xisha waters was investigated. Microplastics were found in all seawater samples, and 90.76 % of C. striatus samples were detected with microplastics. The average abundance of microplastics in seawater samples was 0.64 ± 0.39 items/L, and the abundance of microplastics in the gills and gastrointestinal tracts (GITs)of C. striatus was 1.14 ± 0.41 items/L and 1.80 ± 0.49 items/L, respectively. Shapes of microplastics in the seawater and in the gills and GITs of C. striatus were mainly fibers and films, and the majority of the particle sizes being <1 mm, and the polymers were mainly PET. In addition, the abundance of microplastics in the gills and GITs of C. striatus was positively correlated with that in the seawater, and the correlation was higher in the gills than in the GITs, which means that the accumulation of microplastics in the gills was more closely related to their habitats. The positive correlation between microplastic abundance in the gills and GITs of C. striatus and its body size may be due to the fact that larger individuals have greater energetic demands, require more energy requirements, consume more food, and thus increase the chances of ingesting microplastics.

Spatial distribution characteristics of microplastics in the seawater column and sediments of the artificial reef area and adjacent water in Haizhou Bay

Recently, scholars have been increasing concerned about microplastics (MPs). Unfortunately, information is lacking on the spatial distribution patterns of MPs in coastal seas; therefore, our understanding of the extent of offshore MP contamination remains incomplete. MP distribution in the seawater and surface sediments of an aquaculture area (AA), artificial reef area (AR), and comprehensive effect area (CEA) in Haizhou Bay were investigated in this study. The results showed that the mean abundances of MPs in the surface, middle and bottom seawater were 6.98 ± 3.01 n/m3, 9.12 ± 3.07 n/m3 and 10.20 ± 2.41 n/m3, respectively, and that the abundance in the sediment was 3.09 ± 1.16 n/g. The MP abundance in the bottom seawater was significantly higher than that in the surface seawater (P < 0.05). The correlation among MPs at different depths was not significant, but MPs in most habitats showed a significant correlation. We discovered a significant correlation between the abundance of MPs in the CEA seawater and AR sediments, but not between that in the CEA sediments and AR sediments. MPs can be transported from surface seawater to deeper layers by natural deposition processes. The horizontal transport of MPs due to the coastal gulf current and regular semidiurnal tides lead to the correlations observed in of MP abundance among the AA, CEA, and AR. Migration of MPs from the CEA to the AR was primarily caused by the southern eddies in Haizhou Bay, while migration of MPs from the sediment to the seawater could be due to upwelling in the AR. This was also the main reason there was a lack of a correlation between the sediment from the AR and the seawater from the CEA. This work provides a theoretical and empirical foundation for MP transport and source tracking.

Sublethal Effects of Polystyrene Nanoplastics on the Embryonic Development of Artemia salina (Linnaeus, 1758)

Currents, wave motion, solar radiation, and abrasion are mechanisms responsible for the degradation of large plastic artifacts and contribute to the dispersion of micro and nanoplastics into aquatic ecosystems, which are, currently, the most dangerous threats due to their invisibility and persistence. The present work evaluated the possible lethal and sublethal effects of amino-modified polystyrene nanoplastics (nPS-NH2) with diameters of 50 nm and 100 nm on Artemia salina (A. salina), an organism at the base of the trophic chain of the aquatic system, using a widely used model for the analysis of embryotoxicity from environmental pollutants. For this purpose, after evaluating the biodistribution of nanoplastics in the body of the tested animals, several endpoints such as anomalies, apoptosis, and ROS production were assessed. In addition, particular attention was dedicated to evaluating the correlation between toxicity and the particle size tested. The results reported that, despite the absence of a lethal impact, several sublethal effects involving gut and body size malformations, as well as the enhancement of apoptosis and oxidative stress in relation to an increase in tested concentration and a decrease in nanoparticle size.

Microplastics leaving a trace in mangrove sediments ever since they were first manufactured: A study from Indonesia mangroves

Mangrove environments have been well recognized as marine litter traps. However, it is unclear whether mangrove sediments sink microplastics more effectively than other marine sediments due to active sedimentation. Furthermore, microplastics archives in mangrove sediments may provide quantitative data on the impact of human activities on environmental pollution throughout history. Microplastic abundance varied markedly between high and low anthropogenic activities. Both mangrove and adjacent mudflats sediments act as microplastic sequesters, despite having similar microplastic abundances and depth profiles. The decreasing trend of microplastics was observed until the sediment layers dated to the first-time plastic was manufactured in Indonesia, in the early 1950s, but microplastics remained present beneath those layers, indicating the downward movements. This discovery highlighted the significance of mangrove sediments as microplastic sinks. More research is needed to understand the mechanisms of microplastic deposition in sediments, as well as their fate and potential impact on mangrove sediment dwellers.

Aging behavior of biodegradable polylactic acid microplastics accelerated by UV/H2O2 processes

The usage of biodegradable plastics is expanding annually due to worldwide plastic limits, resulting in a substantial number of microplastics (MPs) particles formed from biodegradable plastic products entering the aquatic environment. Until now, the environmental behaviors of these plastic product-derived MPs (PPDMPs) have remained unclear. In this work, commercially available polylactic acid (PLA) straws and PLA food bags were used to evaluate the dynamic aging process and environmental behavior of PLA PPDMPs under UV/H2O2 conditions. By combining scanning electron microscopy, two-dimensional (2D) Fourier transform infrared correlation spectroscopy (COS) and X-ray photoelectron spectroscopy, it was determined that the aging process of the PLA PPDMPs was slower than that of pure MPs. The 2D-COS analysis revealed that the response orders for the functional groups on the PLA MPs differed during the aging process. The results demonstrated that the oxygen-containing functional groups of the PLA PPDMPs were the first to react. Subsequently, the -C-H and -C-C- structural responses began, and the polymer backbone was ruptured by the aging process. However, the aging of the pure-PLA MPs started with a brief oxidation process and then breakage of the polymer backbones, followed by continuous oxidation. Moreover, compared to the PLA PPDMPs, the pure-PLA MPs exhibited a greater adsorption capacity, which was increased by 88% after aging, whereas those of the two PPDMPs only increased by 64% and 56%, respectively. This work provides new insights into the behaviors of biodegradable PLA MPs in aquatic environments, which is critical for assessing the environmental risks and management policies for degradable MPs.

Occurrence and accumulation of microplastics in commercial fish in the coastal waters of the Lvsi fishing ground in China

In recent years, there has been an exponential increase in the research popularity of microplastics (MPs) in offshore marine environments. However, there is still a gap in the research on the accumulation of MPs in different tissues of aquatic organisms and the trophic transfer of MPs between aquatic organisms. The common occurrence of MPs in the gills and guts of 11 species of commercial fishes was examined in the coastal waters of the Lvsi fishing ground (LSFG). The obtained results showed that >85 % of MPs existed in the gills and guts of these fish, and the abundance was 2.39 ± 1.38 pieces/fish and 2.56 ± 1.42 pieces/fish, respectively. Fibrous and blue are the most common colors and shapes of MPs, and PET is the main polymer type. At the species level, the abundance of MPs in the gills and guts of a few fishes (e.g., Larimichthys polyactis, Setipinna tenuifilis, Collichthys lucidus) decreased with increasing body length and body weight (P < 0.05). At the community level, this situation was not significant (P > 0.05). With increasing trophic level (TL), MPs tended to decrease in the gills (trophic magnification factor, TMF = 0.86) but did not significantly vary in the gut. We believe that MPs are multidimensional pollutants, and their accumulation in tissues/organs of organisms has not been accurately and qualitatively determined. To establish the relationship of MP transport and trophic transfer among water, sediments and organisms, we suggest that more efforts should be made to investigate MPs in aquatic organisms in the coastal waters of LSFG and to increase the examination of MPs in the water column and sediments. This study will help us improve our understanding of MPs pollution, and provide a good reference and basis for the management, monitoring and implementation of pollutants in marine organism of coastal water.

A lesser known but emerging issue, recreational fishing debris and the anglers' opinions in South Korea

The abundance and characteristics of marine debris originating from recreational fishing were examined across 55 sites in four different regions in Korea. The result shows that the average abundance of debris was 4.3 ± 4.2 (n/m2) in terms of the number and 13.4 ± 18.1 (g/m2) in terms of the weight, and the most often found item was fishing lines (<1 m). Detrimental fishing debris such as fishing lines, hooks and weights comprised 50.9 % of the total debris, suggesting significant impacts on wildlife. A questionnaire survey was conducted with 374 anglers across all four regions to understand their behaviors, perceptions, and preferences regarding government policies. Most of the respondents were aware of the adverse impacts of recreational fishing debris on the environment, and >50 % agreed with the introduction of recreational fishing licenses. This study highlights the urgent need to raise awareness and address the undervalued problem of recreational fishing debris.

Prediction of microplastic abundance in surface water of the ocean and influencing factors based on ensemble learning

Microplastics are regarded as emergent contaminants posing a serious threat to the marine ecosystem. It is time-consuming and labor-intensive to determine the number of microplastics in different seas using traditional sampling and detection methods. Machine learning can provide a promising tool for prediction, but there is a lack of research on this. To screen high-performance models for the prediction of microplastic abundance in the marine surface water and explore the influencing factors, three ensemble learning models, random forest (RF), gradient boosted decision tree (GBDT), and extreme gradient boosting (XGBoost), were developed and compared. A total of 1169 samples were collected, and multi-classification prediction models were constructed with 16 features of the data as inputs and six classes of microplastic abundance intervals as outputs. Our results show that the XGBoost model has the best performance of prediction, with a total accuracy rate of 0.719 and an ROC AUC (Receiver Operating Characteristic curve, Area Under Curve) value of 0.914. Seawater phosphate (PHOS) and seawater temperature (TEMP) have negative effects on the abundance of microplastics in surface seawater, while the distance between the sampling point and the coast (DIS), wind stress (WS), human development index (HDI), and sampling latitude (LAT) have positive effects. This work not only predicts the abundance of microplastics in different seas but also offers a framework for the use of machine learning in the study of marine microplastics.

A critical review of microplastics toxicity and potential adverse outcome pathway in human gastrointestinal tract following oral exposure

Microplastics (MPs) are typically produced via environmental degradation of larger plastics, where they enter the human food chain. MPs are complex materials containing chemical and physical characteristics that can potentially affect their hazard and exposure. These physical properties can be altered by environmental exposure potentially altering any risk assessment conducted on the primary material. We conducted a literature review using an Adverse Outcome Pathway (AOP)-based approach from Molecular Initiating Event (MIE) to cell effect event to identify multiple knowledge gaps that affect MPs hazard assessment. There is some convergence of key biological events but could relate to most lying along well-established biological effector pathways such as apoptosis which can respond to many MIEs. In contrast, MIEs of chemicals will be via protein interaction. As MPs may occur in the lumen of the alimentary canal for example to the mucus, therefore, not requiring translocation of MPs across the epithelial membrane. At the other end of the AOP, currently it is not possible to identify a single adverse outcome at the organ level. This work did establish a clear need to understand both external and internal exposure (resulting from translocation) and develop hazard data at both levels to inform on risk assessments.

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

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

Effects of Micro(nano)plastics on the reproductive system: A review

Microplastics (100nm-5 mm) and nanoplastics (1-100 nm) are collectively referred to as micro(nano)plastics (MNPs), which are refractory to degradation, easy to migration, small in size, strong in adsorption, and can widely present in human living environment. A number of studies have confirmed that MNPs can be exposed to the human body through a variety of routes, and can penetrate various barriers to enter the reproductive system, suggesting that MNPs may pose potential harm to human reproductive health. Current studies most were limited to phenotypic studies and their subjects were basically lower marine organisms and mammals. Therefore, in order to provide theoretical base for further exploring the effects of MNPs on the human reproductive system, this paper searched the relevant literature at home and abroad, mainly analyzed rodent experiments, and concluded that the main exposure routes of MNPs are dietary intake, air inhalation, skin contact and medical plastics. After entering the reproductive system, MNPs produce reproductive toxicity mainly through oxidative stress, inflammation, metabolic disorders, cytotoxicity and other mechanisms. More work is required to comprehensively identify the exposure routes, improve the detection methods to evaluate the effective exposure and deeply study the specific mechanisms of toxic effects, withing the aim of conducting relevant studies at the population level in the next step.

Microplastics in coastal and oceanic surface waters and their role as carriers of pollutants of emerging concern in marine organisms

Microplastics (Mps) pose a significant environmental challenge with global implications. To examine the effect of Mps on coastal and oceanic surface waters, as well as in marine organisms, 167 original research papers published between January 2013 and September 2022 were analyzed. The study revealed an unequal distribution of research efforts across the world. Fragments and fibers were the most frequently detected particles in ocean surface waters and marine biota, which mainly consisted of colored and transparent microparticles. Sampling of Mps was primarily done using collecting nets with a mesh size of 330 μm. Most articles used a stereomicroscope and Fourier-Transform Infrared spectroscopy for identification and composition determination, respectively. Polyethylene and polypropylene were the most frequent polymers found, both in coastal waters and in marine organisms. The major impact observed on marine organisms was a reduction in growth rate, an increase in mortality, and reduced food consumption. The hydrophobic nature of plastics encourages the formation of biofilms called the "plastisphere," which can carry pollutants that are often toxic and can enter the food chain. To better define management measures, it is necessary to standardize investigations that assess Mp pollution, considering not only the geomorphological and oceanographic features of each region but also the urban and industrial occupation of the studied marine environments.

Microplastic Index-How to Predict Microplastics Formation?

The presence of microplastics in environmental compartments is generally recognized as a (potential) health risk. Many papers have been published on the abundance of microplastics at various locations around the globe, but only limited knowledge is available on possible mitigation routes. One of the mitigation routes is based on the choice of plastic materials used for products that may unintentionally end up in the environment. As a first approach, this paper presents a method to calculate the tendency of polymers to form microplastics, based on their mechanical and physical properties. A MicroPlastic Index (MPI) that correlates the microplastic formation to polymer properties is defined for both impact and wear of polymers via a theoretical particle size and the energy required to form these particles. A first comparison between calculated and experimental particle size is included. The MPI for impact and wear follow the same trend. Finally, these MPIs are correlated to the respective abundance of the microplastics in the environment, corrected for global production of the corresponding polymers: the higher the MPI, the more microplastics are found in the environment. Thus, the MPI can be used as a basis for choice or redesign of polymers to reduce microplastic formation.

A mixed method assessment of research productivity on microplastics in various compartments in the environment

Microplastic distribution and pollution as emerging contaminants have become a leading environmental issue globally, owing to their ecological and health implications on biota and humans. Although several bibliometric studies have been reported on microplastics, they are mostly restricted to selected environmental media. As a result, the present study aimed at assessing the literature growth trend of microplastics-related research and their distribution in the environment using a bibliometric approach. The Web of Science Core Collection was explored to retrieve published articles on microplastics from 2006 to 2021, and the data were analysed using the Biblioshiny package of RStudio. This study also highlighted filtration, separation, coagulation, membrane technology, flotation, bionanomaterials, bubble barrier devices, and sedimentation as MP remediation techniques. In the present study, a total of 1118 documents were collected from the literature search; the documents/author and authors/document were 0.308 and 3.25, respectively. A significant growth rate of 65.36% was recorded with notable progress between 2018 and 2021. China, the USA, Germany, the UK, and Italy recorded the highest number of publications within the period under consideration. A collaboration index of 3.32 was also relatively high, with the Netherlands, Malaysia, Iran, France, and Mexico having the highest MCP ratios, respectively. It is anticipated that findings from this study will help the policymakers in addressing issues concerning microplastic pollution assist the researchers in identifying areas to concentrate their studies, and where to seek collaboration in their future research plans.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13762-023-04916-7.

Microplastics in water systems: A review of their impacts on the environment and their potential hazards

Microplastics, the microscopic plastics, are fragments of any type of plastic that are being produced today as plastic waste originating from anthropogenic activities. Such microplastics are discharged into the environment, and they enter back into the human body through different means. The microplastics spread in the environment due to environmental factors and the inherent properties of microplastics, such as density, hydrophobicity, and recalcitrance, and then eventually enter the water environment. In this study, to better understand the behavior of microplastics in the water environment, an extensive literature review was conducted on the occurrence of microplastics in aquatic environments categorized by seawater, wastewater, and freshwater. We summarized the abundance and distribution of microplastics in the water environment and studied the environmental factors affecting them in detail. In addition, focusing on the sampling and pretreatment processes that can limit the analysis results of microplastics, we discussed in depth the sampling methods, density separation, and organic matter digestion methods for each water environment. Finally, the potential hazards posed by the behavior of aging microplastics, such as adsorption of pollutants or ingestion by aquatic organisms, due to exposure to the environment were also investigated.

Occurrence, characteristics, and removal of microplastics in wastewater treatment plants located on the Moroccan Atlantic: The case of Agadir metropolis

Wastewater treatment plants (WWTPs) are some of the main sources of microplastics (MPs) in the environment. However, studies on the occurrence and removal efficiency of MPs in WWTPs are still scarce, especially in African countries. Thus, the aim of this work was to study the abundance of MPs in the influent and effluent of two WWTPs (Aourir and M'zar) from the Agadir metropolis (Moroccan Atlantic). The two WWTPs receive different wastewater inputs (domestic and industrial). In addition, the impacts of seasonality on the fate and removal efficiency were investigated. The results showed that the MPs abundance in the wastewater decreased from 188 MPs/L in the influent to 50 MPs/L in the effluent for Aourir WWTP (domestic inputs); while the abundance was greater in the M'zar WWTP (urban and industrial inputs) recording a mean value of 519 MPs/L and 86 MPs/L in the influent and effluent, respectively. MPs collected in the Aourir WWTP ranged from 290 to 3200 μm, while MPs from the M'zar WWTP, ranged from 330 to 4200 μm. Overall, the size range of 100-500 μm was the most abundant for both WWTPs. Fibers were the highest MPs morphotype found, followed by fragments. MP colors were mainly red, black, blue, and transparent for both treatment plants. Additionally, FTIR spectroscopy showed the presence of eight different polymers, mainly polyethylene (PE), polypropylene (PP), and polystyrene (PS). Seasonal variation analysis showed that MPs abundance in summer was significantly higher compared to other seasons. However, the comparison of the removal efficiency (RE) between the different seasons indicated that the winter season (74 %) recorded the highest RE for Aourir WWTP. Conversely, spring (87 %) recorded the highest RE for M'zar WWTP. SEM/EDX micrographs showed different degrees of weathering and chemical elements adhering to the surface of the MPs. The findings of the current study will serve as a baseline for future considerations about management strategies, wastewater reuse, as well as the understanding of the occurrence of microplastic pollution along the marine ecosystems of Morocco.

Floating plastic accumulation and distribution around Kuroshio Current, western North Pacific

The distribution of floating plastic debris around the Kuroshio Current which transports plastics from the coastal waters of Asian countries to North Pacific subtropical gyre, was investigated in 2014. The mean abundance and weight of plastic debris on the sea surface were 100,376 counts/km² and 446.16 g/km², respectively. Intensive plastic accumulation was observed in the frontal area between the northern edge of the Kuroshio and coastal waters off Shikoku, while a relatively higher abundance in the south of Kuroshio was generally associated with anticyclonic mesoscale eddies. Such an accumulation resulted from the eddy-Kuroshio interactions which are specifically associated with the offshore non-large meandering Kuroshio path. Overall, white, fragmented, small-sized (≤1 mm) particles with polyethylene and polypropylene polymers were dominant. In the southern area of Kuroshio, the contribution of polystyrene and larger-sized plastic was higher, suggesting a rapid influx of fresh particles from western Japan to offshore by the northwest monsoon.

Transboundary microplastic pollution in Xiamen Bay and adjacent Jiulong River estuary after the outbreak of COVID-19

Land-based transport from nearshore areas is a key pathway of microplastic (MP) pollution in the oceans. Therefore, transport, fate, and intervention on MPs necessitate an investigation of MP contamination in coastal regions. Here, MP pollution in the surface waters of Xiamen Bay and Jiulong River estuary was evaluated in 2021 after the outbreak of COVID-19. The abundance of MPs in Xiamen Bay ranged from 0.20 to 5.79 items m^-3 with an average of 1.03 items m^-3, whereas that in the Jiulong River estuary spanned from 0.55 to 2.11 items m^-3 with a mean of 1.30 items m^-3. A yearly decreasing trend in the abundance of MPs in surface waters in both regions was observed. The particle sizes of MPs were concentrated in the range of 2.50-5.00 mm, and the colors were mainly white, transparent, and green. The micro-Raman spectroscopic results showed that MP polymer types were predominantly polyethylene, polypropylene, and polystyrene. A lower abundance of MPs in Xiamen Bay with no obvious pattern was observed, while that in the Jiulong River estuary showed a wavelike distribution from upstream to downstream. Ecological risk assessment of MP pollution in surface waters of two regions was performed using the pollution load index (PLI), giving the risk level in descending order: wastewater discharge area > aquaculture area > sloughs > estuary mouth > estuarine rivers > shipping lane. The average risk level of Xiamen Bay (I) was lower than that in Jiulong River estuary (II). The MP pollution in the Jiulong River estuary appeared heavier than that in Xiamen Bay, which may be due to the combined effects of COVID-19 and marine governance. This study provided insights into the prevention and management of MP pollution in nearshore semi-enclosed bays.

Adsorption behavior of UV aged microplastics on the heavy metals Pb(II) and Cu(II) in aqueous solutions

As the "vector" of heavy metals in the aquatic environment, microplastics (MPs) have a great influence on the migration and transformation of heavy metals. In this study, the adsorption of polypropylene (PP), polyethylene (PE) and polystyrene (PS) on two models of heavy metals after UV aging and environmental variables (ionic coexistence, pH, salinity, and fulvic acid) were comprehensively explored on adsorption. The results show that new oxidation functional groups are formed and their hydrophilicity is enhanced after MPs aging. As a result, the adsorption experiments showed that the adsorption of contaminants by UV aged MPs exceeds that of pristine MPs. The adsorption amounts of Pb(II) and Cu(II) by PP, PE and PS increased by 1.45, 1.46, 1.25 and 1.63, 1.39, 1.22 times, respectively. Adsorption kinetic data were more consistent with the pseudo-second-order kinetic model, proving chemisorption to be the mechanism governing the interaction between metal ions and MPs. The Freundlich model could accurately predict the heavy metal adsorption isotherms on MPs, showing that non-homogeneous multilayer adsorption dominates the process. In Pb(II)-Cu(II) binary composite system, metal ion adsorption capacity on MPs is less than that of the single system adsorption capacity, which proves that there is a specific inhibitory effect between coexisting ions. Additionally, external factors like pH, salinity, and fulvic acid content have a big impact on adsorption behavior. According to mechanism analysis, the adsorption process mainly relies on electrostatic interaction, surface complexation, and van der Waals force.

Is there a significant difference in microbiota between water and microplastic surfaces in winter? The possibility of spreading offshore into the ocean

Environmental problems caused by microplastics (MPs) are attracting global attention. The ecological risks of bacteria attached to MPs have not been studied in detail under low temperature conditions. Here, MPs in surface water were sampled in winter from the Changjiang (or Yangtze) River Estuary. The physical and chemical characteristics of the MPs were identified, and the diversity and species composition of bacteria on the surface water MPs were analyzed. Phenotypic prediction analysis was used to analyze the potential risk of bacteria in the biofilm on the surfaces of MPs. The main chemical composition in the MPs in the surface water were PP (polypropylene), PE (polyethylene), PS (polystyrene) and other light weight MPs. Sampling sites played a decisive role in the bacterial species composition. The potential plastic-degrading bacterium Acinetobacter and the potential pathogenic bacterium Pseudomonas showed significant differences across different sampling sites. Microbial communities on the surfaces of MPs in winter were not significantly different from planktonic bacteria in the water body. Phenotypic prediction results showed that bacteria on the surface of MPs had a marked capacity to form biofilms, but a low pathogenicity risk. Based on the results of biodiversity analysis and phenotypic prediction, the potential ecological risk of bacteria in biofilms on MP surfaces is lower at low temperatures. In addition, the numerical simulation results show that the possibility of bacteria attached to MPs from the Changjiang River entering the Pacific Ocean in winter is small. MPs attached bacteria in the Changjiang estuary have low ecological risk to the estuary and the Pacific Ocean in winter.

Microplastic accelerate the phosphorus-related metabolism of bacteria to promote the decomposition of methylphosphonate to methane

Microplastic (MP) contaminants in marine water have become a global public health concern because of their persistence and potentially adverse effects on organisms. MP can affect the growth and metabolism of marine microorganisms and further impact the microbial environmental functions. The molecular impact mechanisms of MP on specific functional microbes with the capability of decomposing methylphosphonate (MPn) to release methane (CH₄) in oxygenated water have rarely been reported upon. Herein, we investigated the effects of MP on microbes and concomitant methanogenesis via the microbial degradation of MPn. Furthermore, the specific perturbation was revealed at the molecular level combined with transcriptomics and metabolomics. The results showed that intracellular phosphorus utilization by MPn-degrading strain Burkholderia sp. HQL1813 was enhanced by accelerating the catabolism of MPn. Phosphorus transport-related genes (phnG-M, pstSCAB, phnCDE) were upregulated in the MP exposure groups. Amino acid metabolism, the phosphotransferase system and nucleotide metabolism were also perturbed after MP exposure. Notably, released CH₄ increased by 24 %, 29 % and 14 % in the exposure group. In addition, the responses of the strain were dose-independent with increasing MP doses. These findings are beneficial for clarifying the effect of MP on specific functional microbes at the molecular level and their degradation of CH₄ by MPn.

Efficient removal of microplastics from aqueous solution by a novel magnetic biochar: performance, mechanism, and reusability

Microplastics' (MPs) pollution removal from water bodies has become an urgent task to ensure water quality safety and water ecological security on a global scale. In this work, coprecipitation was employed to investigate the adsorption of MPs by magnetic biochar (MRB) prepared from agricultural waste rice husks in an aquatic system. The results showed that MRB can adsorb up to 99.96% of MPs in water; acidic conditions were favorable for the effective MPs' adsorption reaction, and competing anions had a greater effect on adsorption. The adsorption mechanism results revealed that the adsorption of MPs by MRB was a spontaneous process, and electrostatic attraction, surface complexation, hydrogen bonding and π-π interactions were present in the adsorption process. Furthermore, after the adsorption of MPs, MRB can be recovered by thermal treatment (500 °C) and still exhibits up to 90% MPs adsorption (after four uses). This work reveals that MRB is an inexpensive, efficient, and reusable nanoscale adsorbent for MPs pollution removal in water, which may provide new ideas for microplastic pollution control in the aqueous environment.

Aging dependent plastic bag derived-microplastics as a vector of metals in lake water

The adsorption of microplastics (MPs) for metals in aquatic environment remains poorly understood due to the use of either commercial MPs, which have different property from the MPs in environments, or artificial solutions, which have not only the significantly higher concentration of metals than natural aqueous environment but also the different natures. In this study, we elaborated the adsorption throughout the aging process of plastic bag derived-MPs (initially 1-2 mm) by potassium persulfate (K₂S₂O₈) solution to metals in lake water. Comparatively, plastic bag derived-MPs had the highest adsorption capacity for Zn²⁺ followed by Fe³⁺, Pb²⁺, Mn²⁺, Cr⁶⁺, Ni²⁺, Cu²⁺ and Cd²⁺, which is not completely consistent with the literature. Both the adsorption capacity and distribution coefficients of Cu²⁺, Ni²⁺, Zn²⁺, Mn²⁺ and Pb²⁺ had significant linear correlation with carbonyl index (p < 0.05). Although the aging overall enhanced the adsorption, the adsorption capacities of MPs might fluctuate depending on metal.

Micro- and nanoplastics: A new cardiovascular risk factor?

Exposure to micro- and nanoplastics (MNPs) is inevitable due to their omnipresence in the environment. A growing body of studies has advanced our understanding of the potential toxicity of MNPs but knowledge gaps still exist regarding the adverse effects of MNPs on the cardiovascular system and underlying mechanisms, particularly in humans. Here, we reviewed up-to-date data published in the past 10 years on MNP-driven cardiovascular toxicity and mechanisms. Forty-six articles concerning ADME (absorption, distribution, and aggregation behaviors) and toxicity of MNPs in the circulatory system of animals and human cells were analyzed and summarized. The results showed that MNPs affected cardiac functions and caused toxicity on (micro)vascular sites. Direct cardiac toxicity of MNPs included abnormal heart rate, cardiac function impairment, pericardial edema, and myocardial fibrosis. On (micro)vascular sites, MNPs induced hemolysis, thrombosis, blood coagulation, and vascular endothelial damage. The main mechanisms included oxidative stress, inflammation, apoptosis, pyroptosis, and interaction between MNPs and multiple cellular components. Cardiovascular toxicity was determined by the properties (type, size, surface, and structure) of MNPs, exposure dose and duration, protein presence, the life stage, sex, and species of the tested organisms, as well as the interaction with other environmental contamination. The limited quantitative information on MNPs' ADME and the lack of guidelines for MNP cardiotoxicity testing makes risk assessment on cardiac health impossible. Furthermore, the future directions of cardiovascular research on MNPs are recommended to enable more realistic health risk assessment.

Size-dependent toxicological effects of polystyrene microplastics in the shrimp Litopenaeus vannamei using a histomorphology, microbiome, and metabolic approach

Due to the wide application of plastic products in human life, microplastic pollution in water has recently attracted more attention. Many studies have revealed the size-dependent toxicity of microplastics. Here, we investigated the toxicological effects of polystyrene microplastics (PS-MPs) on the white leg shrimp, Litopenaeus vannamei, a profitable aquaculture species, using a comprehensive histomorphological, microbiome, and metabolomic approach to verify whether smaller particles are more toxic than larger particles. L. vannamei were experimentally exposed to water containing PS-MPs of four sizes (0.1, 1.0, 5.0, and 20.0 μm) for 24 h at 10 mg/L (acute experiment) and 12 d at 1 mg/L (subchronic experiment). After 24 h of acute exposure, PS-MP accumulation in shrimp indicated that the ingestion and egestion of PS-MPs had a size-dependent effect, and smaller particles were more bioavailable. The tissue morphological results of subchronic experiments showed that, for the guts and gills, the smaller sizes of the PS-MPs exhibited greater damage. In addition, 16 S rRNA gene amplicon sequencing showed that the alpha diversity was higher under larger PS-MP exposure. Correlated with changes in intestinal bacteria, we found a greater enrichment of metabolic pathways in hemolymph proteins and metabolites in larger PS-MP groups, such as "arginine and proline metabolism", "protein digestion and absorption", "lysine degradation". Interestingly, the activity or content of biomarkers of oxidative stress showed a peak at 1 μm and 5 μm. Under specific sizes of PS-MPs, the abundance of the pathogen Vibrio and probiotic bacteria Rhodobacter (5-μm) and Bacillus and Halomonas (1-μm) were simultaneously enriched. Our results indicated that PS-MP exposure can cause size-dependent damage to shrimp, yet specific particle size can be influential differently in regard to some research indicators. Therefore, it can enhance our comprehensive understanding of the impacts of microplastics on shrimp health and suggests that specific particle size should be considered when assessing the size-dependent toxicity of microplastics.