Microplastics in sediments: A review of techniques, occurrence and effects

Effect of chlorination and ultraviolet on the adsorption of pefloxacin on polystyrene and polyvinyl chloride

During the water treatment process, chlorination and ultraviolet (UV) sterilization can modify microplastics (MPs) and alter their physicochemical properties, causing various changes between MPs and other pollutants. In this study, the impact of chlorination and UV modification on the physicochemical properties of polystyrene (PS) and polyvinyl chloride (PVC) were investigated, and the adsorption behavior of pefloxacin (PEF) before and after modification was examined. The effect of pH, ionic strength, dissolved organic matter, heavy metal ions and other water environmental conditions on adsorption behavior was revealed. The results showed that PS had a higher adsorption capacity of PEF than PVC, and the modification increased the presence of O-containing functional groups in the MPs, thereby enhancing the adsorption capacity of both materials. Chlorination had a more significant impact on the physicochemical properties of MPs compared to UV irradiation within the same time period, leading to better adsorption performance of chlorination. The optimal pH for adsorption was found to be 6, and NaCl, sodium alginate and Cu2+ would inhibit adsorption to varying degrees, among which the inhibition caused by pH was the strongest. Chlorination and UV modification would weaken the inhibitory effect of environmental factors on the adsorption of PEF by MPs. The main mechanisms of adsorption involved electrostatic interaction and hydrogen bonding. The study clarified the effects of modification on the physicochemical properties of MPs, providing reference for subsequent biotoxicity analysis and environmental protection studies.

Polyamide microplastics can mitigate the effects of pathogenic bacterium on the health of marine mussels

Vibrio parahaemolyticus and microplastics are prevalent in the ocean. Bacteria attach onto plastic particles, forming harmful biofilms that collectively threaten bivalve health. This study investigates the interaction between polyamide microplastics (PA: particle size 38 ± 12 µm) and V. parahaemolyticus, as well as their combined impact on thick-shelled mussels (Mytilus coruscus). We introduced 1011 CFU/L of V. parahaemolyticus into varying PA concentrations (0, 5, 50, and 500 particles/L) to observe growth over 14 h and biofilm formation after 48 h. Our findings indicate that microplastics suppress biofilm formation and virulence gene expression. Four treatments were established to monitor mussel responses: a control group without PA or V. parahaemolyticus; a group with 50 particles/L PA; a group with 1011 CFU/L V. parahaemolyticus; and a co-exposure group with both 50 particles/L PA and 1011 CFU/L V. parahaemolyticus, over a 14-day experiment. However, combined stress from microplastics and Vibrio led to immune dysregulation in mussels, resulting in intestinal damage and microbiome disruption. Notably, V. parahaemolyticus had a more severe impact on mussels than microplastics alone, yet their coexistence reduced some harmful effects. This study is the first to explore the interaction between microplastics and V. parahaemolyticus, providing important insights for ecological risk assessments.

Microplastic volumes in Tokyo Bay

Microplastic (MP) pollution is a rising environmental concern. This study investigated MP concentrations in Tokyo Bay using neuston net for surface sampling and deep-sea plankton pump for underwater sampling across six stations at multiple depths. Results revealed substantial variation in MP concentrations. Surface large microplastics (LMP, > 350 μm) ranged from 0.21 × 10-3 to 3.34 × 10-3 pieces L-1, averaging 1.26 × 10-3 pieces L-1, while surface small microplastics (SMP, 60 μm to 350 μm) were highest at head of the bay (11.5 ± 3.05 pieces L-1). SMP concentrations varied with depth and position, peaking at center of the bay (5.79 ± 1.63 pieces L-1 at 2 m). Additionally, the total amount of surface LMP was estimated at 10.3 m3 and SMP at 15.0 m3 in the Tokyo Bay. This study provides a comprehensive picture of the spatial and vertical distribution of MP in Tokyo Bay.

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

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

Assessment of anthropogenic particles in Holothuria sanctori from Tenerife (Canary Islands, Spain)

Sea cucumbers play a key role in maintaining the health of coastal marine ecosystems. The aim of this research was to evaluate the presence of anthropogenic particles in sea cucumbers of the species Holothuria sanctori in intertidal pools from Tenerife (Canary Islands, Spain) and in the surrounding seawater. In the case of sea cucumbers (n = 18), the gastrointestinal tract (particles ingested directly from the sediment) and Cuvierian tubules (particles presence as a result of gas exchange with seawater) were analysed separately. Anthropogenic particles were found in all samples, with an average concentration of 20.0 ± 4.4 items per litre in seawater and 11.8 ± 3.9 items per individual in the sea cucumbers, with a higher concentration of particles in the gastrointestinal tract (9.3 ± 3.4 items per gastrointestinal tract) than in the Cuvierian tubules (2.6 ± 3.3 items per Cuvierian tubules). Transparent and blue microfibres were predominant, accounting for over 90 % of the samples analysed. A significant proportion of these fibres were of cellulosic origin (either natural or semisynthetic, comprising 78.7 %), while fully synthetic polymers (microplastics), were also identified, including polyester and polyvinyl chloride (the latter exclusively detected in seawater).

A new green protocol for the identification of microplastics and microfibers in marine sediments, a case study from the Vesuvian Coast, Southern Italy

Microplastics (MP; 1 µm-5 mm) and microfibers (MF; thin, elongated particles with a high-length-to-width ratio) have become a major global environmental issue due to their ubiquity in the oceans and possess complex physicochemical properties that vary their mobility, bioavailability, and toxicity toward organisms and interactions with their surrounding pollutants. Nonetheless, a reliable methodology that would facilitate and automate the monitoring of MP is still lacking. Intending to select practical and standardized methods and considering the challenges in MPs detection, a new analysis protocol based on optical microscopy for the counting and morphological analysis of the particles has been developed. This method overcomes some issues related to the lack of practicality and standardization of the others currently applied, and does not involve sieving, washing, heating, or density separation and digestion processes. Our method is green and requires a minimum quantity of sediment, i.e., 1.5 g, and shortened timeframes. Future research efforts may need to develop and implement new analytical tools and combinations of technologies to complement respective detection limitations and yield reliable characterization of both MFs and MPs. We tested our protocol to study, for the first time, both marine and land sediment in the Vesuvian area of the Gulf of Naples (Italy).

Potential use of gammarus (Pontogammarus maeoticus) and shrimp (Palaemon elegans) as biomonitors of microplastics pollution in coastal environments

Microplastics (MPs) pose a significant threat to marine ecosystems, necessitating robust biomonitoring to assess aquatic risks and inform effective policymaking. In this study we investigated MPs pollution in gammarus (Pontogammarus maeoticus), shrimp (Palaemon elegans), sediment and water samples of southern coast of the Caspian Sea to assess the potential use of these two crustaceans as biomonitors of MPs pollution, bioconcentration of MPs in organisms' tissue and the pollution risks of MPs in environmental matrices. Samples were collected from 6 stations during June to August 2023. MPs were found in all compartments with an average of 100 ± 45.34 items/kg dry weight, 0.45 ± 0.06 items/L, 0.38 ± 0.21 items/individual or 0.58 ± 0.34 items/g wet weight (ww) and 0.26 ± 0.15 items/individual or 8.69 ± 7.88 items/g ww, for sediments, seawaters, P. elegans and P. maeoticus, respectively. MPs were prevailed by class 300-1000 μm in size, polyamide in polymer, fiber in shape and black in color. P. maeoticus and P. elegans did not meet the selection criteria as MPs biomonitors. However, bioconcentration factor (BCF) illustrated that both crustaceans can absorb and accumulate MPs from their surrounding water (BCF >1). Based on contamination factors (CF) values, sampling stations were polluted with MPs (1 ≤ CF < 6). The overall pollution load index (PLI) for sediment and seawater stations were 2.47 and 1.88, respectively, indicating minor contamination with MPs in the risk level I. Current research provides useful information on MPs pollution in crustaceans species and the risk level of MPs in environmental matrices that can be suitable for bioaccumulation hazard assessment and future monitoring programs.

Preparation of Block Copolymer-Stabilized Microspheres from Commercial Plastics and Their Use as Microplastic Proxies in Degradation Studies

This study presents a novel one-pot procedure for preparing sub-10 μm poly(ethylene glycol) (MPEG)-stabilized glycol-modified poly(ethylene terephthalate), poly(ethylene terephthalate) (PET), poly(lactic acid) (PLA), polycarbonate, and polycaprolactone (PCL) particles from commercial plastics. The prepared particles can be dried and directly resuspended in water, making them easy to handle and relevant mimics of microplastics. In addition, the method was extended to the preparation of unstabilized PET particles and somewhat larger polyethylene (PE)-based particles. Selected stabilized microparticles were subjected to aerobic biodegradation studies and compared with nonstabilized PET particles. All of the particles exhibited some degradation. For PLA and PET particles, the degradation corresponded well to the amount of surface-stabilizing MPEG groups or known impurities, confirming that these polymers do not degrade under the applied conditions but that the stabilizing groups do. PCL particles degraded relatively rapidly, which is consistent with the literature data and their relatively small size. PE-based particles degraded more than expected if only degradation of the stabilizing groups was taken into account, indicating that the surface chemistry of these particles plays a role in bulk degradation.

Concentrations and carbonyl index of microplastic in surface seawater in southeastern coastal region off Japan, Northwestern Pacific

In this study, microplastic concentrations in the southeastern coastal regions of Japan were measured along the northward ocean current at seven stations from Okinawa to Tokai region. Concentrations ranged from 0.014 to 0.094 pieces/m3, except for a station near the Bungo Channel mouth, which had 0.723 pieces/m3. Polystyrene (PS) foam was most prevalent near the east side of Kyushu, suggesting origination from nearby coastal areas. Fragmentation levels were higher in the Tokai region. In addition, carbonyl index (CI) of polyethylene (PE) microplastics increased northward, indicating northward movement from southern regions. Standard PE microplastics showed chemical treatment does not significantly alter CI values. Further spectral analysis suggested potential oxidation of polypropylene (PP) and PS foam by chemical treatment. This study provides a comprehensive understanding of the abundance, distribution, and characteristics of microplastics in the southeastern coastal regions of Japan in the northwest Pacific, enhancing the understanding of environmental fate of microplastics.

Oxidative damage and cardiotoxicity induced by 2-aminobenzothiazole in zebrafish (Danio rerio)

There is limited information available on cardiovascular toxicity of 2-Aminobenzothiazole (NTH), a derivative of benzothiazole (BTH) commonly used in tire production, in aquatic organisms. In the present study, the zebrafish embryos were exposed to varying concentrations of NTH (0, 0.05, 0.5, and 5 mg/L) until adulthood and the potential cardiovascular toxicity was assessed. NTH exposure resulted in striking aberrations in cardiac development, including heart looping failure and interference with atrioventricular canal differentiation. RNA-sequencing analysis indicated that NTH causes oxidative damage to the heart via ferroptosis, leading to oxygen supply disruption, cardiac malformation, and ultimately, zebrafish death. Quantitative real-time polymerase chain reaction (qPCR) analysis demonstrated the dysregulation of genes associated with early heart development, contraction, and oxidative stress. Additionally, reactive oxygen species accumulation and glutathione/malondialdehyde levels changes suggested a potential link between cardiac developmental toxicity and oxidative stress. In adult zebrafish, NTH exposure led to ventricular enlargement, decreased heart rate, reduced blood flow, and prolonged RR, QRS, and QTc intervals. To the best of our knowledge, this study is the first to provide evidence of cardiac toxicity and the adverse effects of ontogenetic NTH exposure in zebrafish, revealing the underlying toxic mechanisms connected with oxidative stress damage. These findings may provide crucial insights into the environmental risks associated with NTH and other BTHs.

Biodegradable microplastics aggravate greenhouse gas emissions from urban lake sediments more severely than conventional microplastics

Freshwater ecosystems, such as urban lake sediments, have been identified as important sources of greenhouse gases (GHGs) to the atmosphere, as well as persistent sinks for ubiquitous microplastics due to the high population density and frequent anthropogenic activity. The potential impacts of microplastics on GHG production, however, remain underexplored. In this study, four types of common biodegradable microplastics (BMPs) versus four conventional non-biodegradable microplastics (NBMPs) were artificially exposed to urban lake sediments to investigate the responses of nitrous oxide (N2O) and methane (CH4) production, and make a comparison regarding how the biodegradability of microplastics affected GHG emissions. Importantly, results suggested that BMPs aggravated N2O and CH4 production in urban lake sediments more severely than conventional NBMPs. The production rates of N2O and CH4 increased by 48.78-71.88 % and 30.87-69.12 %, respectively, in BMPs groups, while those increased by only 0-25.69 % and 6.46-10.46 % with NBMPs exposure. Moreover, BMPs insignificantly affected nitrification but facilitated denitrification, while NBMPs inhibited both processes. BMPs not only created more oxygen-limited microenvironment, greatly promoting N2O production via nitrifier denitrification pathway, but also provided dissolved organic carbon favoring heterotrophic denitrification, which was primarily supported by the enriched denitrifiers and functional genes. In contrast, NBMPs slightly upregulated nitrifier denitrification pathway to generate N2O, and showed a toxic inhibition on both nitrifiers and denitrifiers. In addition, both BMPs and NBMPs promoted hydrogen-dependent methanogenic pathway but suppressed acetate-dependent pathway. The greater enhancement of CH4 production with BMPs exposure was attributed to the additional organic carbon substrates derived from BMPs and the stimulated microbial methane metabolism activities.

Potential ecological risk assessment of microplastics in environmental compartments in Mexico: A meta-analysis

Microplastic (MP) environmental contamination has been widely studied in Mexico; however, the evaluation of the associated risk to MP in environmental compartments is scarce. Therefore, this study addresses this issue using diverse indicators such as the Pollution Load Index (PLI), the Polymer Risk Index (PRI), and the Potential Ecological Risk Index (PERI). The results of a meta-analysis revealed high MP contamination levels in most of the studied compartments, which included marine and estuarine waters, beach sand, freshwater, sediments, and biota. Regarding the risk assessment indicators, PLIs indicated low (56%), dangerous (22%), moderate (12%), and high (10%) levels across compartments. Meanwhile, PRIs displayed concerning values, with 36%, 35%, 20%, and 9% exhibiting dangerous, high, moderate, and low levels, respectively. Thus, high PRI values emphasized the significant rise in MP pollution, largely attributed to high-hazard polymer compositions. Otherwise, PERIs showed low (56%), very dangerous (29%), moderate (6%), high (5%), and dangerous (4%) levels. Thus, the ecological risk in Mexico is widespread and mainly linked to MP abundance, polymer type, environmental matrix, and organisms' characteristics. This study represents the first attempt at MP ecological risk assessment in Mexico, providing crucial insights for developing mitigation strategies to address concerns about MP contamination.

A review of plastic debris in the South American Atlantic Ocean coast - Distribution, characteristics, policies and legal aspects

The presence of plastics in the oceans has already become a pervasive phenomenon. Marine pollution by plastics surpasses the status of an emerging threat to become a well-established environmental problem, boosting research on this topic. However, despite many studies on the main seas and oceans, it is necessary to compile information on the South American Atlantic Ocean Coast to identify the lack of research and expand knowledge on marine plastic pollution in this region. Accordingly, this paper conducted an in-depth review of monitoring methods, sampling, and identification of macroplastics and microplastics (MPs) in water, sediments, and biota, including information on legal requirements from different countries as well as non-governmental initiatives. Brazil was the country with the highest number of published papers, followed by Argentina. MPs accounted for 75 % of the papers selected, with blue microfibers being the most common morphology, whereas PE and PP were the most abundant polymers. Also, a lack of standardization in the methodologies used was identified; however, the sites with the highest concentrations of MPs were the Bahía Blanca Estuary (Argentina), Guanabara Bay (Brazil), and Todos os Santos Bay (Brazil), regardless of the method applied. Regarding legislation, Uruguay and Argentina have the most advanced policies in the region against marine plastic pollution due to their emphasis on the life cycle and the national ban on certain single-use plastics. Therefore, considering its content, this expert review can be useful to assist researchers dealing with plastic pollution along the South American Atlantic Ocean Coast.

Quantification and characterization of microplastics ingested by mangrove oysters across West Africa

Microplastic ingestion by marine organisms presents a challenge to both ecosystem functioning and human health. We characterized microplastic abundance, shape, size, and polymer types ingested by the West African mangrove oyster, Crassostrea tulipa (Lamarck, 1819) sampled from estuaries and lagoons from the Gambia, Sierra Leone, Ghana, Benin, and Nigeria using optical microscopy and Fourier transform infrared (FTIR) techniques. A total of 780 microplastics were isolated in the whole tissues of the 250 oysters (n = 50 oysters per country). The abundance and distribution of microplastics in the oysters followed the pattern: the Gambia > Ghana > Sierra Leone > Nigeria > Benin. The Tanbi wetlands in the Gambia recorded the highest average of 10.50 ± 6.69 per oyster while the Ouidah lagoon in Benin recorded the lowest average of 1.80 ± 1.90 per oyster. Overall, microplastic numbers varied significantly (p < 0.05) among the five countries. Microfibers, particularly those within 1001-5000 μm size, dominated the total microplastic count with a few fragments and films. No spherical microplastics were isolated in the oysters. In the Sierra Leone and Benin oysters, fragments and films were absent in the samples. Microplastic between the 1001 and 5000 μm size class dominated the counts, followed by 501-1000 μm, 101-500 μm, and 51-100 μm. Five polymer groups namely polyethylene, polyester, nylon, polypropylene, and polyamide were identified across the five countries, with polyethylene occurring in oysters from all five countries and polyester occurring in all but the oysters from Nigeria. This diversity of polymers suggests varied sources of microplastics ingested by the studied oysters. The absence of microspheres across the five supports findings from other studies that they are the least ingested and highly egested by the oysters.

Short-term microplastic effects on marine meiofauna abundance, diversity and community composition

Background

Due to the copious disposal of plastics, marine ecosystems receive a large part of this waste. Microplastics (MPs) are solid particles smaller than 5 millimeters in size. Among the plastic polymers, polystyrene (PS) is one of the most commonly used and discarded. Due to its density being greater than that of water, it accumulates in marine sediments, potentially affecting benthic communities. This study investigated the ingestion of MP and their effect on the meiofauna community of a sandy beach. Meiofauna are an important trophic link between the basal and higher trophic levels of sedimentary food webs and may therefore be substantially involved in trophic transfer of MP and their associated compounds.

Methods

We incubated microcosms without addition of MP (controls) and treatments contaminated with PS MP (1-µm) in marine sediments at three nominal concentrations (103, 105, 107particles/mL), for nine days, and sampled for meiofauna with collections every three days. At each sampling time, meiofauna were collected, quantified and identified to higher-taxon level, and ingestion of MP was quantified under an epifluorescence microscope.

Results

Except for Tardigrada, all meiofauna taxa (Nematoda, turbellarians, Copepoda, Nauplii, Acari and Gastrotricha) ingested MP. Absorption was strongly dose dependent, being highest at 107 particles/mL, very low at 105 particles/mL and non-demonstrable at 103 particles/mL. Nematodes accumulated MP mainly in the intestine; MP abundance in the intestine increased with increasing incubation time. The total meiofauna density and species richness were significantly lower at the lowest MP concentration, while at the highest concentration these parameters were very similar to the control. In contrast, Shannon-Wiener diversity and evenness were greater in treatments with low MP concentration. However, these results should be interpreted with caution because of the low meiofauna abundances at the lower two MP concentrations.

Conclusion

At the highest MP concentration, abundance, taxonomic diversity and community structure of a beach meiofauna community were not significantly affected, suggesting that MP effects on meiofauna are at most subtle. However, lower MP concentrations did cause substantial declines in abundance and diversity, in line with previous studies at the population and community level. While we can only speculate on the underlying mechanism(s) of this counterintuitive response, results suggest that further research is needed to better understand MP effects on marine benthic communities.

Rose or Red, but Still under Threat: Comparing Microplastics Ingestion between Two Sympatric Marine Crustacean Species (Aristaeomorpha foliacea and Parapenaeus longirostris)

Increasing plastic contamination poses a serious threat to marine organisms. Microplastics (MPs) ingestion can represent a risk for the organism itself and for the ultimate consumer. Through the analysis of the gastrointestinal tract, coupled with stable isotope analysis on the muscle tissue, this study provides insights into the relationship between MPs pollution and ecology in two commercial marine species caught in the Central Tyrrhenian Sea: Aristaeomorpha foliacea and Parapenaeus longirostris. Stable isotope analysis was conducted to determine the trophic position and the trophic niche width. The gastrointestinal tracts were processed, and the resultant MPs were analysed under FT-IR spectroscopy to estimate the occurrence, abundance, and typology of the ingested MPs. The trophic level of the species was similar (P. longirostris TP = 3 ± 0.10 and A. foliacea TP = 3.1 ± 0.08), with an important trophic niche overlap, where 38% and 52% of P. longirostris and A. foliacea has ingested MPs, respectively. Though species-level differences may not be evident regarding MP's abundance per individual, a high degree of dissimilarity was noted in the typologies of ingested particles. This research provides valuable insights into how MPs enter marine trophic webs, stressing that isotopic niche analysis should be combined with other methods to explain in detail the differences in MPs ingestion.

Microplastic abundance in the semi-enclosed Osaka Bay, Japan

Anthropogenic particles in sea surface water of the semi-enclosed Osaka Bay were identified using stereomicroscopy, classified according to polymer type using Fourier-transform infrared spectroscopy (FTIR), and categorized according to their physical characteristics. A total of 565.1 particles were detected in the water samples. However, plastic particles accounted for only 22.4% of the particles. Microplastic abundance in Osaka Bay showed seasonal variance from 8.9 ± 1.4 (in May) to 22.8 ± 6.5 particles/L (in July), which is consistent with previous reports in other semi-enclosed bays. Microplastics were mainly fragmented and fiber shaped, with gray and colorless/white coloration. The dominant polymer types were polypropylene, poly(methylmethacrylate), polyester, polyethylene, and polyethylene terephthalate. Generally, there were considerably higher abundances of microplastics at offshore sites compared with nearshore sites. The results of this study suggest that local river effluents and marine-related activities are probable sources of microplastics in Osaka Bay.

Microplastic pollution and ecological risk assessment of a pond ecosystem

Microplastic (MP) pollution has been observed in various ecosystems as a result of the rapid increase in plastic production over the past half-century. Nevertheless, the extent of MP pollution in different ecosystems, particularly in freshwater ecosystems, has not been well-studied, and there are limited investigations on this particular topic, specifically in Türkiye. Here, we quantify the occurrence and distribution of MPs in surface water samples collected from Topçu Pond (Türkiye) for the first time. Water samples were collected at five stations and filtered (30 L for each station) through stacked stainless steel sieves (5 mm, 328 µm, and 61 µm mesh size) with a diameter of 30 cm. The abundance, size, color, shape, and type of collected debris samples were analyzed after the wet peroxide oxidation process. MP particles were observed in all samples at an average abundance of 2.4 MPs/L. The most abundant MP size class and type were 0-999 µm and fiber respectively. On the other hand, prevalent colors were black and colorless in general. According to the Raman analysis results, the identified MP derivatives were polypropylene (40%), polyamide (30%), ethylene acrylic acid (20%), and polyvinylchloride (10%). Moreover, the pollution load index (PLI) index was used to determine the pollution status. PLI values were determined as 1.91 at station S1, 1.73 at station S2, 1.31 at station S3, 1 at station S4 and 1.24 at station S5. The PLI value determined for the overall pond was 1.4. The results of this research show that MP pollution is present in Topçu Pond and contributes to the expanding literature on MP pollution in pond ecosystems.

Effects of microplastics on key reproductive and biochemical endpoints of the freshwater microcrustacean Daphnia magna

Human activities have directly impacted the environment, causing significant ecological imbalances. From the different contaminants resulting from human activities, plastics are of major environmental concern. Due to their high use and consequent discharge, plastics tend to accumulate in aquatic environments. There, plastics can form smaller particles (microplastics, MPs), due to fragmentation and weathering, which are more prone to interact with aquatic organisms and cause deleterious effects, including at the basis of different food webs. This study assessed the effects of two microplastics (polyethylene terephthalate, PET; and polypropylene, PP; both of common domestic use) in the freshwater cladoceran species Daphnia magna. Toxic effects were assessed by measuring reproductive traits (first brood and total number of offspring), and activities of biomarkers involved in xenobiotic metabolism (phase I: cytochrome P-450 isoenzymes CYP1A1, 1A2 and 3A4; phase II/conjugation: glutathione S-transferases; and antioxidant defense (catalase)). Both MPs showed a potential to significantly reduce reproductive parameters in D. magna. Furthermore, PET caused a significant increase in some isoenzymes of CYP450 in acutely exposed organisms, but this effect was not observed in chronically exposed animals. Similarly, the activity of the antioxidant defense (CAT) was significantly increased in acutely exposed animals, but not in chronically exposed organisms. This pattern of effects suggests a possible mechanism of long-term adaptation to the presence of the tested MPs. In conclusion, the herein tested MPs have shown the potential to induce deleterious effects on D. magna mainly observed in terms of the reproductive outcomes. Changes at the biochemical level seems transient and are not likely to occur in long term, environmentally exposed crustaceans.

Effect and environmental behaviour of microplastics in soil

Soil microplastic pollution is currently a worldwide concern. Microplastics are organic pollutants that are abundant in the natural environment, are persistent and difficult to degrade and may endanger human health while harming the environment. This article offers a bibliometric analysis of the environmental behaviour of microplastics in soils, as well as a thorough statistical analysis of research goals and trends in this field. We conducted a thorough search of all relevant literature from 2012 to 2022 in the Web of Science core database. The data analysis shows that, starting in 2012, there has been an upward trend in the number of articles about soil microplastic pollution. It can also be seen that China is relatively ahead of the curve in this area of research, followed by the United Kingdom and the United States. This article also systematically describes the research hotspots in this field. The results show that the current research on soil microplastics is mainly focused on their identification, enrichment and toxicity, whereas studies on the migration and transformation of soil microplastics and the mechanism of interaction with other pollutants are still lacking. Our results provide ideas and prospects for future research in this field.

Pilot-scale performance of gravity-driven ultra-high flux fabric membrane systems for removing small-sized microplastics in wastewater treatment plant effluents

The ubiquitous nature and environmental impacts of microplastic particles and fibers demand effective solutions to remove such micropollutants from sizable point sources, including wastewater treatment plants and road runoff facilities. While advanced methods, e.g., microfiltration and ultrafiltration, have shown high removal efficiencies of small-sized microplastics (<150 μm), the low flux encountered in these systems implies high operation costs and makes them less effective in high-capacity wastewater facilities. The issue presents new opportunities for developing cheap high-flux membrane systems, deployable in low-to high-income economies, to remove small-sized microplastic and nanoplastics in wastewater. Here, we report on developing an ultra-high flux gravity-driven fabric membrane system, assessed through a laboratory-scale filtration and large-scale performance in an actual wastewater treatment plant (WWTP). The method followed a carefully designed water sampling, pre-treatment protocol, and analytical measurements involving Fourier transform infrared (FTIR) spectroscopy and laser direct infrared (LDIR) imaging. The result shows that the ultra-high flux (permeance = 550,000 L/m2h⋅bar) fabric membrane system can effectively remove small-sized microplastics (10-300 μm) in the secondary effluent of an actual WWTP at high efficiency greater than 96 %. The pilot system demonstrated a continuous treatment capacity of 300,000 L/day through a 1 m2 surface area disc, with steady removal rates of microplastics. These findings demonstrate the practical, cheap, and sustainable removal of small-sized microplastics in wastewater treatment plants, and their potential value for other large-scale point sources, e.g., stormwater treatment facilities.

Unveiling microplastic distribution and interactions in the benthic layer of the Yangtze River Estuary and East China Sea

Microplastics (MPs), recognized as an emerging global environmental concern, have been extensively detected worldwide, with specific attention directed towards the Yangtze River Estuary (YRE) and East China Sea (ECS) regions. Despite their critical research significance, there remains a knowledge gap concerning the distribution of MPs in the benthic layer within this area, particularly regarding interactions governing their occurrence. Here we illuminate the distribution of MPs within the benthic layer and unravel the intricate interplay between bottom water and sediment in the YRE and ECS. We find that MPs are notably more abundant in bottom water, ranging from 8 to 175 times higher than in surface water. These MPs predominantly consist of polyester fibers, exhibit a size range between 0.5 and 5.0 mm, and display distinct coloration. Co-occurrence network analysis and Principal Coordinate Analysis confirm a robust correlation between MPs in bottom water and sediment, signifying the pivotal role of bottom water in mediating the distribution and transportation of MPs within the benthic layer. Furthermore, a positive correlation between MPs in sediment and bottom water turbidity underscores the impact of surface sediment resuspension and upwelling on MPs distribution. This study clarifies the intricate interactions within the benthic layer and highlights the crucial role of bottom water as a mediator in the vertical distribution of MPs, advancing our understanding of the "source-to-sink" transport processes governing MPs within water-sediment systems.

Centennial Records of Microplastics in Lake Cores in Huguangyan Maar Lake, China

Microplastic records from lake cores can reconstruct the plastic pollution history. However, the associations between anthropogenic activities and microplastic accumulation are not well understood. Huguangyan Maar Lake (HML) is a deep-enclosed lake without inlets and outlets, where the sedimentary environment is ideal for preserving a stable and historical microplastic record. Microplastic (size: 10-500 μm) characteristics in the HML core were identified using the Laser Direct Infrared Imaging system. The earliest detectable microplastics appeared unit in 1955 (1.1 items g-1). The microplastic abundance ranged from n.d. to 615.2 items g-1 in 1955-2019 with an average of 134.9 items g-1. The abundance declined slightly during the 1970s and then increased rapidly after China's Reform and Opening Up in 1978. Sixteen polymer types were detectable, with polyethylene and polypropylene dominating, accounting for 23.5 and 23.3% of the total abundance, and the size at 10-100 μm accounted for 80%. Socioeconomic factors dominated the microplastic accumulation based on the random forest modeling, and the contributions of GDP per capita, plastic-related industry yield, and total crop yield were, respectively, 13.9, 35.1, and 9.3% between 1955-2019. The total crop yield contribution further increased by 1.7% after 1978. Coarse sediment particles increased with soil erosion exacerbated microplastics discharging into the sediment.

Environmental impact of microplastics and potential health hazards

Microscopic plastic (microplastic) pollutants threaten the earth's biodiversity and ecosystems. As a result of the progressive fragmentation of oversized plastic containers and products or manufacturing in small sizes, microplastics (particles of a diameter of 5 mm with no lower limit) are used in medicines, personal care products, and industry. The incidence of microplastics is found everywhere in the air, marine waters, land, and even food that humans and animals consume. One of the greatest concerns is the permanent damage that is created by plastic waste to our fragile ecosystem. The impossibility of the complete removal of all microplastic contamination from the oceans is one of the principal tasks of our governing body, research scientists, and individuals. Implementing the necessary measures to reduce the levels of plastic consumption is the only way to protect our environment. Cutting off the plastic flow is the key remedy to reducing waste and pollution, and such an approach could show immense significance. This review offers a comprehensive exploration of the various aspects of microplastics, encompassing their composition, types, properties, origins, health risks, and environmental impacts. Furthermore, it delves into strategies for comprehending the dynamics of microplastics within oceanic ecosystems, with a focus on averting their integration into every tier of the food chain.

Macroplastic and Microparticle Pollution in Beach Sediments from Urias Coastal Lagoon (Northwest Mexico)

This study investigates the occurrence and characteristics of macroplastic and polymer microparticles in the Urias coastal lagoon's beach sediments, in northwest Mexico. Coastal lagoons, productive and vulnerable ecosystems, are impacted significantly by anthropogenic activities, leadings to their pollution by various contaminants, including plastics. Our research involved sampling sediments from four sites within the lagoon that were influenced by different human activities such as fishing, aquaculture, thermoelectric power plant operations, industrial operations, and domestic wastewater discharge. Our methodology included collecting macroplastics and beach sediment samples, followed by laboratory analyses to identify the plastic debris' size, shape, color, and chemical composition. The results indicated a notable presence of macroplastic items (144), predominantly bags, styrofoam, and caps made of polyethylene (PE), polypropylene (PP), and polyethylene terephthalate (PET). The polymer microparticles were mainly fibers, with cotton and polyester as the most common polymers, suggesting a significant contribution from clothing-related waste. The dominant colors of the microparticles were blue and transparent. High densities were observed in areas with slower water exchange. Our findings highlight the urgent need for better waste management practices to mitigate plastic pollution in coastal lagoons, preserving their ecological and economic functions.

Effects of micro- and nano-plastics on growth, antioxidant system, DMS, and DMSP production in Emiliania huxleyi

Due to the potential impacts of microplastics (MPs) and nanoplastics (NPs) on algal growth and thereby affect the climate-relevant substances, dimethylsulfoniopropionate (DMSP) and dimethyl sulfide (DMS), we studied the polystyrene (PS) MPs and NPs of 1 μm and 80 nm impacts on the growth, chlorophyll content, reactive oxygen species (ROS), antioxidant enzyme activity, and DMS/DMSP production in Emiliania huxleyi. E. huxleyi is a prominent oceanic alga that plays a key role in DMS and DMSP production. The results revealed that high concentrations of MPs and NPs inhibited the growth, carotenoid (Car), and Chl a concentrations of E. huxleyi. However, short-time exposure to low concentrations of PS MPs and NPs stimulated the growth of E. huxleyi. Furthermore, high concentrations of MPs and NPs resulted in an increase in the superoxide anion radical (O2.-) production rate and a decrease in the malondialdehyde (MDA) content compared with the low concentrations. Exposure to MPs and NPs at 5 mg L-1 induced superoxide dismutase (SOD) activity as a response to scavenging ROS. High concentrations of MPs and NPs significantly inhibited the production of DMSP and DMS. The findings of this study support the potential ecotoxicological impacts of MPs and NPs on algal growth, antioxidant system, and dimethylated sulfur compounds production, which maybe potentially impact the global climate.

A Study of High-Frequency Noise for Microplastics Classification Using Raman Spectroscopy and Machine Learning

Given the growing urge for plastic management and regulation in the world, recent studies have investigated the problem of plastic material identification for correct classification and disposal. Recent works have shown the potential of machine learning techniques for successful microplastics classification using Raman signals. Classification techniques from the machine learning area allow the identification of the type of microplastic from optical signals based on Raman spectroscopy. In this paper, we investigate the impact of high-frequency noise on the performance of related classification tasks. It is well-known that classification based on Raman is highly dependent on peak visibility, but it is also known that signal smoothing is a common step in the pre-processing of the measured signals. This raises a potential trade-off between high-frequency noise and peak preservation that depends on user-defined parameters. The results obtained in this work suggest that a linear discriminant analysis model cannot generalize properly in the presence of noisy signals, whereas an error-correcting output codes model is better suited to account for inherent noise. Moreover, principal components analysis (PCA) can become a must-do step for robust classification models, given its simplicity and natural smoothing capabilities. Our study on the high-frequency noise, the possible trade-off between pre-processing the high-frequency noise and the peak visibility, and the use of PCA as a noise reduction technique in addition to its dimensionality reduction functionality are the fundamental aspects of this work.

Spectral analysis of environmental microplastic polyethylene (PE) using average spectra

In this study, microplastic samples from surface seawater of Tokyo Bay were collected, polyethylene (PE) microplastics were used to calculate carbonyl index (CI), and average spectra of PE were analyzed and compared with a previous study applying agitation during chemical treatment. It was found that PE and polypropylene (PP) were the predominant polymer type in the samples. Among PE samples, fragments were the most commonly observed shape, with white being the dominant color. Deviations were found in the average spectra among different shapes and colors when compared to the standard PE spectrum. A comparison of the average spectra between the two datasets suggests that pronounced peaks related to oxidation are most likely resulted from agitation during the chemical treatment. Additionally, it was found a closer spectral resemblance between the sample spectra and the spectrum of standard sample of oxidized PE (PEOx) than with the standard PE spectrum, suggesting that using the oxidized PE as a reference spectrum might be more effective for identification. These findings highlight the complex factors affecting the spectral properties of microplastics and highlight the importance of understanding these variations to enhance the accuracy of microplastic identification workflows and understanding of environmental fate of microplastics.

Presence of microplastics in estuarine environment: a case study from Kavvayi and Kumbla backwaters of Malabar Coast, Kerala, India

Microplastics (MPs) are gaining global attention in recent years due to its widespread distribution and potential health impacts. The present study focuses on the distribution and characterisation of microplastics in the sediments and its transfer into the organisms living in Kavvayi and Kumbla backwaters of Northern Malabar region, Kerala, India. MP isolation procedures including density separation, organic matter digestion, and membrane filtration followed by visual and spectral analyses using optical microscope and confocal Raman spectroscopy have been utilised for the microplastic evaluation. Microplastics of size range up to 1 μm was analysed, and the presence of MPs was detected in all samples with an average abundance of 99.5 ± 69.43 particles/kg and 96.57 ± 29.96 particles/kg in Kavvayi and Kumbla backwaters respectively. Raman spectral analysis confirmed that almost 50% of MPs to be synthetic elastomers with the remaining half encompassed by polyamide, polyethylene, polyester, polyurethane, and polypropylene. Higher abundance of MPs in the edible aquatic organisms like clams, prawns, and fishes confirmed the transfer of MP from the environment into living organisms envisages the need of further investigation on toxicological impacts and management strategies.

Current Concerns about Microplastics and Nanoplastics: A Brief Overview

The widespread and increasing use of plastic-based goods in the present-day world has been raising many concerns about the formation of microplastics, their release, their impacts on the environment and, ultimately, on living organisms. These concerns are even greater regarding nanoplastics, i.e., nanosized microplastics, which may have even greater impacts. In this brief review, although without any claim or intention to exhaustively cover all the aspects of such a complex and many-sided issue, the very topical problem of the formation of microplastics, and the even more worrisome nanoplastics, from polymer-based products was considered. The approach is focused on a terse, straightforward, and easily accessible analysis oriented to the main technological engineering aspects regarding the sources of microplastics and nanoplastics released into the environment, their nature, some of the consequences arising from the release, the different polymers involved, their technological form (i.e., products or processes, with particular attention towards unintentional release), the formation mechanisms, and some possible mitigation pathways.

Investigating the distribution of microplastics in soils from e-waste dismantling sites and their adsorption of heavy metals

Microplastics are characterized by strong hydrophobicity, large specific surface area. In addition to the pollutant they contain, the heavy metals adsorbed on the surface of microplastics can migrate or be transformed with them into the environmental medium, which is potentially harmful to humans. The distribution characteristics of microplastics in contaminated soil at the e-waste dismantling site were studied. The study investigated the adsorption characteristics of polyvinyl chloride (PVC), polypropylene (PP) and acrylonitrile-butadiene-styrene (ABS) on copper (Cu), zinc (Zn) and lead (Pb). It analysed the influence of various factors on the adsorption process of heavy metals, the adsorption law of microplastics on some of the heavy metals in the environment, and the risk of heavy metal release from microplastics to soil. The results showed that ABS and PP were the main microplastics in the contaminated soil. Among them, black, white and transparent microplastics accounted for 89.91%. The shape of microplastics is mainly granular, and microplastics with a particle size of 1-2 mm accounted for the largest proportion. Further studies showed that plastic particles made of ABS, PP and PVC also have the adsorption capacity for different types of heavy metals in soil, and the trends of adsorption capacity are: PP>PVC>ABS. When PP does not reach adsorption equilibrium in the adsorption process, the smaller the particle size and the more added amount, the greater the adsorption capacity. This is because the smaller the particle size of the microplastic is, the more adsorption points it can provide, increasing its ability to adsorb heavy metal ions.

Exposure to microplastics renders immunity of the thick-shell mussel more vulnerable to diarrhetic shellfish toxin-producing harmful algae

Despite both microplastics (MPs) and harmful algae blooms (HABs) may pose a severe threat to the immunity of marine bivalves, the toxification mechanism underlying is far from being fully understood. In addition, owing to the prevalence and sudden occurrence characteristics of MPs and HABs, respectively, bivalves with MP-exposure experience may face acute challenge of harmful algae under realistic scenarios. However, little is known about the impacts and underlying mechanisms of MP-exposure experience on the susceptibility of immunity to HABs in bivalve mollusks. Taking polystyrene MPs and diarrhetic shellfish toxin-producing Prorocentrum lima as representatives, the impacts of MP-exposure on immunity vulnerability to HABs were investigated in the thick-shell mussel, Mytilus coruscus. Our results revealed evident immunotoxicity of MPs and P. lima to the mussel, as evidenced by significantly impaired total count, phagocytic activity, and cell viability of haemocytes, which may result from the induction of oxidative stress, aggravation of haemocyte apoptosis, and shortage in cellular energy supply. Moreover, marked disruptions of immunity, antioxidant system, apoptosis regulation, and metabolism upon MPs and P. lima exposure were illustrated by gene expression and comparative metabolomic analyses. Furthermore, the mussels that experienced MP-exposure were shown to be more vulnerable to P. lima, indicated by greater degree of deleterious effects on abovementioned parameters detected. In general, our findings emphasize the threat of MPs and HABs to bivalve species, which deserves close attention and more investigation.

Determination of Microplastics in Omega-3 Oil Supplements

Microplastics (MPs) are ubiquitous in the environment, posing a threat to ecosystems and causing increasing concerns regarding their impacts on the human body through exposure. However, there has been limited research on the presence of MPs in functional foods, despite them being consumed for health improvement. This study aimed to investigate MP occurrence in various omega-3 oils and oil products in the Korean market and its relation to the source of raw material or manufacture. MPs were investigated in omega-3 capsules and raw oil, sourced from both plant-based (PB) and animal-based (AB) sources. We developed a method of direct filtration with acetone washing for collecting and characterizing MPs larger than 5 μm using micro-Raman spectroscopy. The average number of MPs by mass was found to be 1.2 ± 1.7 MPs/g for PB raw oil, 2.2 ± 1.7 MPs/g for AB raw oil, 3.5 ± 3.9 MPs/g for PB capsule oil, and 10.6 ± 8.9 MPs/g for AB capsule oil. Polypropylene and polyethylene terephthalate were the major MP species (83-95%) found in omega-3 oil. The proportions based on size range remained consistent across all groups, with a trend of being detected at higher rates as the size decreased. The results reveal that the main reason for the MP contamination of omega-3 oil is not the source of raw material but the manufacturing and packaging process.

Altitudinal variation of microplastic abundance in lakeshore sediments from Italian lakes

Microplastic (MP) contamination represents an issue of global concern for both aquatic and terrestrial ecosystems, but only in recent years, the study of MPs has been focused on freshwaters. Several monitoring surveys have detected the presence of a wide array of MPs differing in size, shape, and polymer composition in rivers and lakes worldwide. Because of their role of sink for plastic particles, the abundance of MPs was investigated in waters, and deep and shoreline sediments from diverse lakes, confirming the ubiquity of this contamination. Although diverse factors, including those concerning anthropogenic activities and physical characteristics of lakes, have been supposed to affect MP abundances, very few studies have directly addressed these links. Thus, the aim of the present study was to explore the levels of MP contamination in mountain and subalpine lakes from Northern Italy. Fourteen lakes dislocated at different altitudes and characterized by dissimilar anthropic pressures were visited. Lakeshore sediments were collected close to the drift line to assess MPs contamination. Our results showed the presence of MPs in lakeshore sediments from all the lakes, with a mean (± standard deviation) expressed as MPs/Kg dry sediment accounting to 14.42 ± 13.31 (range 1.57-61.53), while expressed as MPs/m2, it was 176.07 ± 172.83 (range 25.00-666.67). The MP abundance measured for Garda Lake was significantly higher compared to all the other ones (F1,13 = 7.344; P < 0.001). The pattern of contamination was dominated by fibers in all the lakes, but they were the main contributors in mountain lakes. These findings showed that the MP abundance varied according to the altitude of the lakes, with higher levels measured in subalpine lakes located at low altitudes and surrounded by populated areas.

The power of Posidonia oceanica meadows to retain microplastics and the consequences on associated macrofaunal benthic communities

In the coastal environment, a large amount of microplastics (MPs) can accumulate in the sediments of seagrass beds. However, the potential impact these pollutants have on seagrasses and associated organisms is currently unknown. In this study, we investigated the differences in MPs abundance and composition (i.e., shape, colour and polymer type) in marine sediments collected at different depths (-5 m, -15 m, -20 m) at two sites characterized by the presence of Posidonia oceanica meadows and at one unvegetated site. In the vegetated sites, sediment samples were collected respectively above and below the upper and lower limits of the meadow (-5 m and -20 m), out of the P. oceanica meadow, and in the central portion of the meadow (-15 m). By focusing on the central part of the meadow, we investigated if the structural features (i.e. shoots density and leaf surface) can affect the amount of MPs retained within the underlying sediment and if these, in turn, can affect the associated benthic communities. Results showed that the number of MPs retained by P. oceanica meadows was higher than that found at the unvegetated site, showing also a different composition. In particular, at vegetated sites, we observed that MPs particles were more abundant within the meadow (at - 15 m), compared to the other depths, on unvegetated sediment, with a dominance of transparent fragments of polypropylene (PP). We observed that MPs entrapment by P. oceanica was accentuated by the higher shoots density, while the seagrass leaf surface did not appear to have any effect. Both the abundance and richness of macrofauna associated with P. oceanica rhizomes appear to be negatively influenced by the MPs abundance in the sediment. Overall, this study increases knowledge of the potential risks of MPs accumulation in important coastal habitats such as the Posidonia oceanica meadows.

Spatial and temporal trends of microplastic contamination in surface sediment of Benoa Bay: An urban estuary in Bali-Indonesia

This study aims to explore microplastic contamination in the sediments of Benoa Bay. Eight locations were sampled, with four duplications denoting the rainy and dry seasons. Based on observations, the microplastic concentration varied from 9.51 to 90.60 particles/kg with an average of 31.08 ± 21.53 particles/kg. The area near the landfill had the highest abundance, while the inlet and center of Benoa Bay and the Sama River had the lowest concentration. The fragments (52.2 %) and large microplastic sizes (64.7 %) were the most documented particles. We also identified 17 polymers, which dominated (37.5 %) by polyethylene, polypropylene, and polystyrene. There were no appreciable variations in abundance between seasons, although there were substantial variations in shape and size. Comprehensive investigation, adequate policies, continuous monitoring, and reducing waste from land- and sea-based sources that engage various stakeholders must be implemented urgently to prevent the release of microplastic into the aquatic ecosystem.

Monitoring of microplastic pollution in sediments along the Çoruh River Basin, NE Türkiye

Microplastic (MP) pollution has become a research issue on the world agenda. Monitoring studies are essential for MP content in aquatic environments since it is the final accumulation point. The present study focused on MP characterizations in sediment samples taken from 20 different stations on the Çoruh River, the major river in the North East of Türkiye. Accordingly, the potential anthropogenic pollution from settlements near the four stations (2, 15, 18, and 20) exceeding 400 MP kg-1 was estimated. On the other hand, stations (1, 3, 9, 11, and 13) far from settlements with quite low MP abundance were also observed. The polymer structures of the detected MPs are generally PE and PET, and their shapes are mostly fiber. This situation raises suspicion that MPs originate from primary use waste such as water bottles and packaging materials. In general, the fiber MPs are smaller than the fragments because of the river's high water flow rate and the low strength of the fiber MPs. In light of these results, the current monitoring data in the region will create awareness and guidance regarding MP pollution in settlements.

Towards the understanding of the uptake and depuration of microplastics in the ragworm Hediste diversicolor: Field and laboratory study

An important number of studies have evaluated the presence of microplastics, particles with a size below 5 mm, in aquatic organisms. Studies have shown that these fragments are widely present in the marine environment, but research on the estuarine ecosystem is still scarce. In this study, two different approaches were used to evaluate the presence and ingestion of plastic particles in the ragworm Hediste diversicolor: a field study for the environmental assessment and a laboratory experiment in controlled condition. For the environmental evaluation, ingestion of microplastics was evaluated in the ragworm H. diversicolor sampled from the mudflats of the Seine estuary (France) during March and June 2017 and 2018, on two locations: S1 and S2, both characterized by high anthropogenic pressures, and for S2 a more influential hydrodynamic component. Ingestion of microplastics was measured in ragworms tissues and in gut content (sediment) after depuration. The number of particles as well as their size, shape and color were reported and compared between sampling period and locations. Results showed the presence of a low number of particles in both worms and gut content. In gut content, 45.6% and 87.58% of samples from site S1 and S2 respectively contained plastic like particles. In worms, 41.7% (S1) and 75.8% (S2) of analysed samples contained plastic like items. The lowest mean number of particles was 0.21 ± 0.31 (S1 in June 2017) in worms' tissues, but 0.80 ± 0.90 (S1 in June 2017) in the gut content and the highest was 1.47 ± 1.41 (S2 in April 2017) while the highest number was 2.55 ± 2.06 (S2 in June 2017) in worms and gut content respectively. The majority of suspected microplastics observed were fibers (66%) and fragments (27%), but films (3.7%) foam (2.1%), and granules (0.2%) were also identified. In addition, the most polymer type observed by Raman spectroscopy was polypropylene. Furthermore, a preliminary study of the ingestion and egestion of fluorescent polyethylene (PE) microbeads in the digestive tract of ragworms was conducted after exposure through water, during 1h at 1.2 × 106 MP/mL. Results showed a rapid turnover of PE microbeads throughout the digestive tract of worms especially after exposure through water. This study revealed that microplastics are ingested by the ragworm H. diversicolor but do not seem to bioaccumulate. More research is needed to measure potential chronic effects of microplastics on physiological parameters of H. diversicolor and potential trophic transfer of microplastics.

Microplastics in beach sediments of the Azores archipelago, NE Atlantic

Oceanic islands are exposed to plastic debris that has accumulated in the open ocean, particularly in the subtropical gyres. This study investigates the abundance and typology of microplastics (from 0.1 to 5 mm) on 19 sandy beaches spread across 8 oceanic islands of the Azores archipelago. Between January and April 2016, a total of 341 particles retrieved from all beaches, were identified as microplastics. The highest concentration (50.19 ± 21.93 particles kg-1 dw) was found in Terceira Island. Beach morphology and grain size were important factors explaining microplastic concentration. Fibres were the most dominant morphology recovered (80.9 %), followed by fragments (12.3 %). Fourier transform infrared spectroscopy (FTIR) revealed that 41 % of the fibres consisted of polyester and 60 % of the fragments were polyethylene. This research underlines the widespread contamination of microplastics in oceanic islands of the Atlantic Ocean.

Organophosphate ester additives and microplastics in benthic compartments from the Loire estuary (French Atlantic coast)

We report the first empirical confirmation of the co-occurrence of organophosphate esters (OPEs) additives and microplastics (MPs) in benthic compartments from the Loire estuary. Higher median concentrations of MPs (3387 items/kg dw), ∑13tri-OPEs (12.0 ng/g dw) and ∑4di-OPEs (0.7 ng/g dw) were measured in intertidal sediments with predominance of fine particles, and under higher anthropogenic pressures, with a general lack of seasonality. Contrarily, Scrobicularia plana showed up to 4-fold higher ∑tri-OPE concentrations in summer (reaching 37.0 ng/g dw), and similar spatial distribution. Polyethylene predominated in both compartments. Tris(2-ethylhexyl) phosphate (TEHP), its degradation metabolite (BEHP) and tris-(2-chloro, 1-methylethyl) phosphate (TCIPP) were the most abundant OPEs in sediments, while TCIPP predominated in S. plana. The biota-sediment accumulation factors suggest bioaccumulation potential for chlorinated-OPEs, with higher exposure in summer. No significant correlations were generally found between OPEs and MPs in sediments suggesting a limited role of MPs as in-situ source of OPEs.

Abundance and risk assessment of microplastics in water, sediment, and aquatic insects of the Nile River

Microplastics (MPs) are a serious threat in freshwater environments. The ecological risk and abundance level of MPs in abiotic and biotic compartments of the Nile River haven't been systematically reported. Thus, these issues were highlighted in the present study during different seasons of the sampling year. The results showed that MP concentrations in the river ranged from 2.24 ± 0.6 to 3.76 ± 1.1 particles/L, 298 ± 63 to 520 ± 80 particles/kg dry weight, and 0.081 ± 0.051 to 4.95 ± 2.6 particles/individual in surface water, sediment, and different species of aquatic insects, respectively. All the extracted MPs are colored blue, red, and black. Fiber-shaped polyesters (<500-1500 μm) were the most common MPs in all the river compartments. MPs' dominance was observed during the summer in comparison with that in the other seasons. Environmental risk indicators indicate the high ecological risk of MPs, which are widely distributed in the Nile River. In conclusion, MP consumption by aquatic insects may not only be related to levels of environmental contamination, since other variables, such as taxon size, weight, and particular feeding behavior, may also be significant. Additionally, the presence of MPs in insects (at lower trophic levels) creates the potential for predation-based inter-trophic level transmission. Thus, higher trophic-level investigations of various feeding groups should be carried out to identify any possible harm that MPs cause to various aquatic organisms.

Microplastics and TiO2 nanoparticles mixture as an emerging threat to amphibians: A case study on bullfrog embryos

Emerging contaminants can act as contributing factors to the decline of amphibian populations worldwide. Recently, scientists have drawn attention to the potential ecotoxicity of microplastics and nanomaterials in amphibians, however, their possible effects on embryonic developmental stages are still absent. Thus, the present study analyzed the developmental toxicity of environmentally relevant concentrations of polyethylene microplastics (PE MPs; 60 mg/L) and titanium dioxide nanoparticles (TiO2 NPs; 10 μg/L), isolated or in combination (Mix group) on bullfrog embryos, Aquarana catesbeiana, adapting the Frog Embryo Teratogenesis Assay (FETAX, 96h). Allied to the FETAX protocol, we also analyzed the heart rate and morphometric data. The exposure reduced the survival and hatching rates in groups exposed to TiO2 NPs, and to a lesser extent, also affected the Mix group. TiO2 NPs possibly interacted with the hatching enzymes of the embryos, preventing hatching, and reducing their survival. The reduced effects in the Mix group are due to the agglomeration of both toxicants, making the NPs less available for the embryos. PE MPs got attached to the gelatinous capsule of the chorion (confirmed by fluorescence microscopy), which protected the embryos from eventual direct effects of the microplastics on the hatching and survival rates. Although there were no cardiotoxic effects nor morphometric alterations, there was a significant increase in abdominal edemas in the hatched embryos of the PE MPs group, which indicates that osmoregulation might have been affected by the attachment of the microplastics on the embryos' gelatinous capsule. This study presents the first evidence of developmental toxicity of environmental mixtures of microplastics and nanoparticles on amphibians and reinforces the need for more studies with other amphibian species, especially neotropical specimens that could present bigger sensibility. Our study also highlighted several features of the FETAX protocol as useful tools to evaluate the embryotoxicity of several pollutants on amphibians.

Microplastic pollution in stream sediments discharging from Türkiye's eastern Black sea basin

Rivers are the principal route for terrestrial microplastics to reach the marine environment. The Black Sea exhibits a notable representation because it has a drainage zone almost six times the surface area and is semi-closed, meaning that microplastics tend to gather there. To mitigate MP pollution, it is necessary to identify the contamination sources and then raise public awareness. Thus, the current study focused on the MP presence in the sediment of streams running into the SE Black Sea. 594 MPs were observed in sediment samples from 16 stations along the 350 km coastline. The abundance of MP was higher, particularly in streams that pass through locations with high tourism and industrial activity levels. Detected MPs ranged between 0.1 and 5 mm, while the overall density was smaller than 1 mm. Fragments and fiber MPs were regularly detected, although the presence of films was rarely recorded. The polymer structures that were most commonly observed in the analyzed pollutants were PET and PE. The current study uncovered MP contamination in stream sediments originating from Türkiye's Eastern Black Sea basin and might be a baseline work for future inland water studies.

Microplastics strengthen nitrogen retention by intensifying nitrogen limitation in mangrove ecosystem sediments

Mangrove wetlands are hotspots of the global nitrogen (N) cycle and important sinks of microplastics (MPs) due to their ecotone location between terrestrial and marine ecosystems. However, the effects of MPs on N cycle processes in mangrove ecosystems are still poorly understood. Thus, the present study assessed the impacts by adding MPs to mangrove sediments in a microcosm incubation experiment. The results showed that MPs increased dissolved organic carbon and nitrate but reduced ammonium contents in the sediments. MPs increased C:N stoichiometric and N:C-acquiring enzymatic ratios, indicating an intensified N limitation in mangrove sediments following exposure of MPs. MPs decreased microbial community diversity and shifted sediment microbial communities from r- to K-strategists, consistent with the intensified N limitation. In response, dissimilatory nitrate reduction to ammonium (DNRA) rates increased while nitrous oxide (N2O) production reduced suggesting more efficient N utilization in MPs treatments. The MPs with heteroatoms such as PLA- and PVC-MPs, increased DNRA rates by 67.5-78.7%, exhibiting a stronger impact than PE-MPs. The variation partitioning analysis revealed that the variances of DNRA rates and N2O production could be attributed to synergistic effects of physicochemical properties, nutrient limitation, and microbial community in mangrove sediments. Overall, this study provides pertinent insights into the impacts of MPs as a new carbon source on nutrient limitation and N turnover in mangrove ecosystems.

Platinum vaporization-deposition coated polycarbonate membranes for comprehensive, multimodal, and correlative microscopic analysis of micro-and nanoplastics and other environmental particles

Anthropogenic particles, including microplastics, are receiving ever-increasing concern due to their potential environmental impact. Surveys and monitoring require sampling from many environmental and biological matrices, including natural water, drinking water, sediment, and air. However, there are no standard methods for sampling particles in the environment; thereby, many different approaches are used for both single particle and ensemble distribution or bulk chemical analyses. In the microplastics field, particles are often analyzed on membranes using automated analysis with spectroscopic techniques such as Fourier-transform infrared spectroscopy (FTIR) and Raman spectroscopy. For automated analysis, the filters' properties are crucial. We coated polycarbonate (PC) membranes with 100 nm platinum (Pt) on both side using a e-beam evaporator and evaluated their suitability for filtrating and analysis of environmental samples. The PC membranes have a defined and practical pore size, available in many pore sizes and with circular diameter of 47 mm and 25 mm. Our Pt coated membranes can handle large volumes of fresh and marine waters, high pressure, and various treatment solutions. Moreover, they have good optical properties for imaging with light microscopy (LM) and Scanning Electron Microscopy (SEM), and no disturbing background signal for Raman or FTIR spectroscopy analysis.

Marine microdebris pollution in sediments from three environmental coastal areas in the southwestern Argentine Atlantic

Microplastics (MPs) and antifouling paint particles (APPs) are important components of marine microdebris (MDs), which constitute a potential environmental risk. This study analyzed baseline contamination levels of MDs and mesodebris (MesDs) in intertidal sediments at different depths, exploring the geomorphological influence in three Argentine coastal environments: Bahía Blanca Estuary (BBE), Los Pocitos (LP) and Puerto Madryn (PM). The MDs and MesDs samples were characterized by μ-FTIR, SEM/EDX and XRD. The abundance of MPs and APPs in sediments, range between 19.78 and 1087.19 and between 0 and 172.93 items/kg d.w., respectively. Despite variations in population and industrial developments in these areas, MPs abundance shows no significant differences in low and high intertidal zones. However, mean MPs concentrations were higher in the surface layer (0-5 cm) compared to the deeper sediments (5-10 cm), indicating recent MPs deposition. Chemical characterization evidenced the presence of cellulose (CE) and denser polymers as acrylonitrile butadiene styrene (ABS) and polyacrylics (PAN), APPs, metallic and black MDs. Surface degradation and heavy metals (Zn, Cr, and Ba) were also detected in APPs and other MDs, either as additives or adhered to their surfaces. Changes in crystallinity were also observed on the MesDs due to weathering. The calculated polymer hazard index (PHI) and the presence of hazardous polymers such as ABS and PAN indicated an increased risk of MPs pollution on the BBE and PM coasts. The pollution load index (PLI) values (from 4.63 to 5.34) suggested unpolluted to moderately polluted levels. These findings offer insights into potential risks associated with MDs in Argentine intertidal sediments, underscoring the critical need to comprehend the geomorphology and the influence of coastal dynamics. This is crucial for effectively addressing challenges linked to MDs pollution guiding the development of robust management and mitigation strategies.

Do contaminants compromise the use of recycled nutrients in organic agriculture? A review and synthesis of current knowledge on contaminant concentrations, fate in the environment and risk assessment

Use of nutrients recycled from societal waste streams in agriculture is part of the circular economy, and in line with organic farming principles. Nevertheless, diverse contaminants in waste streams create doubts among organic farmers about potential risks for soil health. Here, we gather the current knowledge on contaminant levels in waste streams and recycled nutrient sources, and discuss associated risks. For potentially toxic elements (PTEs), the input of zinc (Zn) and copper (Cu) from mineral feed supplements remains of concern, while concentrations of PTEs in many waste streams have decreased substantially in Europe. The same applies to organic contaminants, although new chemical groups such as flame retardants are of emerging concern and globally contamination levels differ strongly. Compared to inorganic fertilizers, application of organic fertilizers derived from human or animal feces is associated with an increased risk for environmental dissemination of antibiotic resistance. The risk depends on the quality of the organic fertilizers, which varies between geographical regions, but farmland application of sewage sludge appears to be a safe practice as shown by some studies (e.g. from Sweden). Microplastic concentrations in agricultural soils show a wide spread and our understanding of its toxicity is limited, hampering a sound risk assessment. Methods for assessing public health risks for organic contaminants must include emerging contaminants and potential interactions of multiple compounds. Evidence from long-term field experiments suggests that soils may be more resilient and capable to degrade or stabilize pollutants than often assumed. In view of the need to source nutrients for expanding areas under organic farming, we discuss inputs originating from conventional farms vs. non-agricultural (i.e. societal) inputs. Closing nutrient cycles between agriculture and society is feasible in many cases, without being compromised by contaminants, and should be enhanced, aided by improved source control, waste treatment and sound risk assessments.

Study on the release of microplastic particles with different particle sizes in sediments caused by wave-induced liquefaction

Every year, almost 1.15-2.41 million tons of plastic from terrestrial rivers undergo fragmentation under certain conditions and settle in the estuarine delta and shallow marine shelf areas, making this region a "sink" for land-based microplastics. Owing to its fast deposition rate, relatively soft sediment bed, and shallow water depth, the estuarine delta region is prone to liquefaction under high wind and wave conditions. This could potentially release deeply buried microplastic particles during the liquefaction process, posing further threats to marine ecology and human health. To investigate this phenomenon, laboratory experiments were conducted using a water tank to simulate wave-induced liquefaction of sediment beds. The results showed that under the influence of wave-induced liquefaction, 56.2 % of microplastic particles were released back into the sediment surface, with larger particles being released to a greater extent. Based on these experimental results, this study also analyzed and discussed the release rate and mechanisms of microplastic particles from sediment during wave-induced liquefaction, estimating that the maximum release rate of microplastic particles under the experimental conditions could reach 0.34 mm/min.

Polystyrenenanoplastics lead to ferroptosis in the lungs

INTRODUCTION

It has been shown that polystyrenenanoplastic (PS-NP) exposure induces toxicity in the lungs.

OBJECTIVES

This study aims to provide foundational evidence to corroborate that ferroptosis and abnormal HIF-1α activity are the main factors contributing to pulmonary dysfunction induced by PS-NP exposure.

METHODS

Fifty male and female C57BL/6 mice were exposed to distilled water or 100 nm or 200 nm PS-NPs via intratracheal instillation for 7 consecutive days. Hematoxylin and eosin (H&E) and Masson trichrome staining were performed to observe the histomorphological changes in the lungs. To clarify the mechanisms of PS-NP-induced lung injury, we used 100 μg/ml, 200 μg/ml and 400 μg/ml 100 or 200 nm PS-NPs to treat the human lung bronchial epithelial cell line BEAS-2B for 24 h. RNA sequencing (RNA-seq) of BEAS-2B cells was performed following exposure. The levels of glutathione, malondialdehyde, ferrous iron (Fe2+), and reactive oxygen species (ROS) were measured. The expression levels of ferroptotic proteins were detected in BEAS-2B cells and lung tissues by Western blotting. Western blotting, immunohistochemistry, and immunofluorescence were used to evaluate the HIF-1α/HO-1 signaling pathway activity.

RESULTS

H&E staining revealed substantial perivascular lymphocytic inflammation in a bronchiolocentric pattern, and Masson trichrome staining demonstrated critical collagen deposits in the lungs after PS-NP exposure. RNA-seq revealed that the differentially expressed genes in PS-NP-exposed BEAS-2B cells were enriched in lipid metabolism and iron ion binding processes. After PS-NP exposure, the levels of malondialdehyde, Fe2+, and ROS were increased, but glutathione level was decreased. The expression levels of ferroptotic proteins were altered significantly. These results verified that PS-NP exposure led to pulmonary injury through ferroptosis. Finally, we discovered that the HIF-1α/HO-1 signaling pathway played an important role in regulating ferroptosis in the PS-NP-exposed lung injury.

CONCLUSION

PS-NP exposure caused ferroptosis in bronchial epithelial cells by activating the HIF-1α/HO-1 signaling pathway, and eventually led to lung injury.

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.