Microplastics as vectors of contaminants

Demonstrating the translocation of nanoplastics across the fish intestine using palladium-doped polystyrene in a salmon gut-sac

Fish are widely reported to ingest microplastics with low levels accumulating in the tissues, but owing to analytical constraints, much less is known about the potential accumulation of nanoplastics via the gut. Recently, the labelling of plastics with inorganic metals (e.g., palladium) has allowed measurements of nanoplastic uptake. The aim of the current study was to quantitatively assess the uptake of nanoplastics by the fish gut using palladium-doped nanoplastics (with a mean hydrodynamic radius of 202 ± 7 nm). By using an ex vivo gut sac exposure system, we show that in 4 h between 200 and 700 million nanoplastics (representing 2.5-9.4% of the administered nanoplastics dose) can enter the mucosa and muscularis layers of the intestine of salmon. Of the particles taken up, up to 700,000 (representing 0.6% of that taken into the tissue) of the nanoplastics passed across the gut epithelium of the anterior intestine and exit into the serosal saline. These data, generated in highly controlled conditions provide a proof-of-concept study, suggesting the potential for nanoplastics to distribute throughout the body, indicating the potential for systemic exposure in fish.

Influence of Particle Size on Ecotoxicity of Low-Density Polyethylene Microplastics, with and without Adsorbed Benzo-a-Pyrene, in Clam Scrobicularia plana

This study investigated the ecotoxicological effects of differently sized (4–6 µm and 20–25 µm) low-density polyethylene (LDPE) microplastics (MPs), with and without adsorbed benzo-a-pyrene (BaP), in clam Scrobicularia plana. Biomarkers of oxidative stress (superoxide dismutase—SOD; catalase—CAT), biotransformation (glutathione-S-transferases—GST), oxidative damage (lipid peroxidation—LPO) and neurotoxicity (acetylcholinesterase—AChE) were analysed in gills and digestive glands at different time intervals for a total of 14 days of exposure. In order to have a better impact perspective of these contaminants, an integrated biomarker response index (IBR) and Health Index were applied. Biomarker alterations are apparently more related to smaller sized (4–6 µm) MPs in gills and to virgin LDPE MPs in the digestive gland according to IBR results, while the digestive gland was more affected by these MPs according to the health index.

Enhanced propagation of intracellular and extracellular antibiotic resistance genes in municipal wastewater by microplastics

Microplastics (MPs) are an emerging global concern as they are abundant in the environment and can act as vectors of various contaminants. However, whether and how MPs can be vectors of antibiotic resistance genes (ARGs), especially extracellular ARGs (eARGs), remains far from explicit. This study addresses the adsorption of both intracellular ARGs (iARGs) and eARGs by four types of MPs in municipal wastewater, and then explores the potential horizontal gene transfer of iARGs and eARGs exposed to MPs. Results indicate that though MPs significantly adsorbed both iARGs and eARGs, eARGs were adsorbed with a significantly higher fold enrichment (2.0-5.0 log versus 2.0-3.3 log) and rate (0.0056 min^-1 versus 0.0037 min^-1) than iARGs. While all four types of MPs adsorbed ARGs, polypropylene MPs showed the highest adsorption capacity for ARGs. Background constituents such as humic acid and antibiotics significantly inhibited adsorption of iARGs, but not eARGs on MPs. The presence of sodium chloride didn't significantly affect adsorption of iARGs or eARGs. The adsorption of ARGs was well explained by the extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) interaction energy profile. Higher eARG adsorption was attributed to a lower energy barrier between MPs and eARGs than that between MPs and iARGs. Exposure to MPs enhanced horizontal gene transfer of both iARGs and eARGs by 1.5 and 2.0 times, respectively. The improved contact potential between donors and recipients, as well as the increased cell permeability of recipients induced the improved horizontal gene transfer by MPs. This study underscores the need to address ARG propagation through adsorption to MPs.

A comparative review of microplastics in lake systems from different countries and regions

Microplastics, as defined here as plastics with a diameter of <5 mm, can impose severely detrimental impacts on the environment and can now be commonly found in different water bodies. To date, the status of microplastics in limnic systems, which have different hydrologic systems compared to other water bodies such as oceans or rivers, has rarely been reviewed. In the present study, the microplastic pollutants in different countries and regions were comparatively investigated in terms of their abundances, morphologies, and polymer types in the water and sediments of lakes. The concentration and characteristics of microplastics were found to be largely different across countries and regions, which was related to the local development level and economic structure. The migration paths of microplastics in the inner and external limnic ecosystems further revealed the causes for the regional divergence in microplastics. Policy developments in different countries and regions were also discussed to highlight the urgency of better controlling microplastic pollution in lake systems. The characteristics of microplastics vary across countries and regions, depending on the local development level and economic structure.

Porous microplastics enhance polychlorinated biphenyls-induced thyroid disruption in juvenile Japanese flounder (Paralichthys olivaceus)

Microplastics and polychlorinated biphenyls are ubiquitous in the marine environments. To illuminate their combined biological impacts, juvenile Japanese flounder (Paralichthys olivaceus) were exposed to 500 ng/L PCBs alone or 500 ng/L PCBs plus 2, 20, and 200 μg/L 10-μm porous MPs for 21 days. Compared to PCBs alone, co-exposure to PCBs and 20, 200 μg/L MPs reduced fish body length and body weight, and the concurrence of MPs aggravated PCBs-induced thyroid-disrupting effects, including significantly decreased L-thyroxine and L-triiodothyronine levels, more severe damage to the thyroid tissue and gill morphology, and disturbance on the expression of hypothalamus-pituitary-thyroid axis genes. The PCBs concentrations in the seawater were decreased dramatically with the increase of MPs concentrations, confirming that MPs absorbed PCBs from the seawater. Our results demonstrated that MPs enhanced the thyroid disruption of PCBs, suggesting that the risk of MPs and thyroid-disrupting chemicals on marine organisms should be paid more attention.

Microplastics deteriorate the removal efficiency of antibiotic resistance genes during aerobic sludge digestion

Sludge from wastewater treatment plants (WWTPs) is considered to be reservoirs of antibiotic resistance genes (ARGs), which can be efficiently removed by sludge treatment processes, e.g., aerobic sludge digestion. However, recent studies report microplastics, which also accumulate in sludge, may serve as carriers for ARGs. In the presence of microplastics, whether ARGs can still be efficiently destroyed by aerobic sludge digestion remains to be urgently investigated. In this study, the fate of ARGs during aerobic digestion was investigated with and without the addition of three prevalent categories of (i.e., polyvinyl chloride (PVC), polyethylene (PE), and polyethylene terephthalate (PET)). Nine ARGs and class 1 integron-integrase gene (intI1) that represents the horizontal transfer potential of ARGs were tested in this study. Compared with the control, the ARGs removal efficiency decreased by 129.6%, 137.0%, and 227.6% with the presence of PVC, PE, and PET, respectively, although a negligible difference was observed with their solids reduction efficiencies. The abundance of potential bacterial hosts of ARGs and intI1 increased in the reactors with the addition of microplastics, suggesting that microplastics potentially selectively enriched bacterial hosts and promoted the horizontal transfer of ARGs during aerobic sludge digestion. These may have contributed to the deteriorated ARGs removal efficiency. This study demonstrated that microplastics in sludge would decrease the ARGs removal efficiency in aerobic digestion process, potentially leading to more ARGs entering the local environment during sludge disposal or utilization.

Legislation to limit the environmental plastic and microplastic pollution and their influence on human exposure

Plastic pollution is an emerging problem and is a consequence of the post-consumer plastic waste accumulation in the environment coupled to mismanaged waste programmes. Countries are counteracting the continuous growth of plastic litter with different strategies: introducing bans and limits on both plastic items and materials, promoting plastic recycling and recovery strategies and encouraging voluntary clean up actions, as well as raising public awareness. However, the toxicity of plastics to the environment and organisms is not only related to their polymer chains, but also to the fact that plastic materials contain hazardous additives and can adsorb environmental pollutants (i.e. heavy metals and persistent organic contaminants, respectively). The plastic/additives/pollutants combination may be ingested by marine organisms and then enter in the food chain. Therefore, legislation for additives and contaminants is crucial both to reduce environmental pollution and their toxic effects on organisms, which of course includes humans. In this review, the current policies on plastics and related contaminants are described focusing on current laws. Moreover, recommendations for seafood consumption are suggested, since each fish or mollusc eaten may potentially result in plastic particles, additives or contaminants ingestion.

Simultaneous sorption behaviors of UV filters on the virgin and aged micro-high-density polyethylene under environmental conditions

The simultaneous sorption behaviors of four analytes from the UV filters group, benzophenone (BPh), 4-methylbenzylidene camphor (4MBC), benzophenone 3 (BPh3), and benzophenone 2 (BPh2) on virgin and aged high-density polyethylene (HDPE) with a particle size of 125 μm in milliQ and river water were examined in this study. The aging processes of HDPE particles were carried out with the use of simulated sunlight. Conducted research revealed that the sorption of UV filters on HDPE particles follows pseudo-second-order kinetics. A Temkin isothermal model best described the adsorption process for 4BMC, BPh, BPh3, BPh2 on aged HDPE in river water, and 4MBC, BPh, BPh3 on virgin HDPE in milliQ water. The adsorption of BPh2 onto virgin MPs in milliQ water was consistent with the Langmuir isothermal model. Environmental conditions and physicochemical properties of analytes influenced the sorption mechanism between UV filters and MPs particles. It was observed that the main mechanisms responsible for the sorption of BPh, 4MBC, BPh3, and BPh2 on the surface of HDPE are hydrophobic interactions, that may change through the involvement of electrostatic interactions.

The COVID-19 pandemic and its implications on the environment

The emerging threat posed by COVID-19 pandemic has strongly modified our lifestyle, making urgent to re-consider the humans-environment relationships and stimulating towards more sustainable choices in our daily behavior. Scientific evidences showed that the onset of new viral pathogens with a high epidemic-pandemic potential is often the result of complex interactions between animals, humans and environment. In this context, the interest of the scientific community has also been attracted towards the potential interactions of SARS-CoV-2 with environmental compartments. Many issues, ranging from the epidemiology and persistence of SARS-CoV-2 in water bodies to the potential implications of lockdown measures on environmental quality status are here reviewed, with a special reference to marine ecosystems. Due to current sanitary emergence, the relevance of pilot studies regarding the interactions between SARS-CoV-2 spread and the direct and indirect environmental impacts of the COVID-19 pandemic, that are still a matter of scientific debate, is underlined.

Effects of pristine microplastics and nanoplastics on soil invertebrates: A systematic review and meta-analysis of available data

In laboratory studies, microplastics and/or nanoplastics (MPs/NPs) have been shown to cause a variety of ecotoxicological effects on soil invertebrates. Existing data on the effects of these plastic debris on biological functions and physiological systems, showed a great variability among studies. Thus, how soil invertebrates respond to different types, shapes, sizes and concentrations of pristine MPs/NPs remains to be further characterized. The present work is an up-to-date review on quantitative and qualitative data on the effects of pristine MPs/NPs on soil invertebrates in laboratory conditions. Research priorities are also discussed. Out of a total of 1061 biological endpoints investigated in 56 studies, 49% were significantly affected after exposed to pristine MPs/NPs. The polymers with chloro and phenyl groups had more negative impacts on soil invertebrates than other polymers. Most studies used earthworm and nematode species as model organisms. For nematodes, the impact of MPs/NPs seemed to be concentration-dependent and higher concentrations of pristine MPs/NPs appeared to have more adverse impacts on biological functions and physiological systems, but this trend was not confirmed in earthworms. Meta-analysis revealed that pristine MP/NP concentrations higher than 1 g kg^-1 (in soil) may decrease growth and survival of earthworms, while a concentration higher than 1 μg L^-1 (in water) may affect nematode reproductive fitness.

Microplastics in the Environment: Intake through the Food Web, Human Exposure and Toxicological Effects

Recently, studies on microplastics (MPs) have increased rapidly due to the growing awareness of the potential health risks related to their occurrence. The first part of this review is devoted to MP occurrence, distribution, and quantification. MPs can be transferred from the environment to humans mainly through inhalation, secondly from ingestion, and, to a lesser extent, through dermal contact. As regards food web contamination, we discuss the microplastic presence not only in the most investigated sources, such as seafood, drinking water, and salts, but also in other foods such as honey, sugar, milk, fruit, and meat (chickens, cows, and pigs). All literature data suggest not-negligible human exposure to MPs through the above-mentioned routes. Consequently, several research efforts have been devoted to assessing potential human health risks. Initially, toxicological studies were conducted with aquatic organisms and then with experimental mammal animal models and human cell cultures. In the latter case, toxicological effects were observed at high concentrations of MPs (polystyrene is the most common MP benchmark) for a short time. Further studies must be performed to assess the real consequences of MP contamination at low concentrations and prolonged exposure.

Microplastics as a vehicle of exposure to chemical contamination in freshwater systems: Current research status and way forward

Contamination by microplastics is increasing steadily worldwide, affecting all environments. Additionally, aquatic organisms are often exposed to mixtures of other contaminants, including various chemicals. Numerous studies reported adsorption of chemicals to microplastics, raising concern about their possible role as vehicles of exposure through transfer to biota. Nevertheless, until recently, the studies on the topic were mostly focused on the marine environment. In the past five years, however, plenty of publications contributed empirical data about freshwater ecosystems, raising the need for a critical appraisal of the information. Herein the scientific literature was reviewed and multivariate data analysis was done. The analysed studies employed widely different experimental designs, endpoints, test species, shapes and concentrations of various polymer types and chemicals, often not relevant for the freshwater environment. Our integrated analytical approach revealed unfathomable research gaps, given the theoretical knowledge available and lessons learned from research about the marine environment. Greater harmonization of laboratory studies investigating this topic is needed, as well as testing conditions reflecting real exposure scenarios. Furthermore, standardized testing protocols are urgently required to guide such experiments and improve the comparability of the results obtained.

Synthesis of dominant plastic microfibre prevalence and pollution control feasibility in Chinese freshwater environments

Microplastic pollution of freshwaters is known to be a great concern in China and these pollutants can be discharged into the coastal environment through fluvial processes, posing threats to the global marine ecosystem. This paper reviewed the literature measuring microplastic pollution in the Chinese freshwater environment and found that microfibres dominate other plastic morphologies in more than 65% of samples collected in surface water, sediments and effluents of wastewater treatment plants and domestic sewers. Current potential sources of microfibre pollution are identified including fishery activities, laundry sewage, and waste textiles according to previous research. Recommendations are offered using the circular economy management framework, such as textile waste reuse and recycling systems in China, for improving current control measures for microplastics in freshwaters.

Diversity Loss in Coralligenous Structuring Species Impacted by Fishing Gear and Marine Litter

Coralligenous structuring species (CSS) form a group of marine megabenthic species with an engineering capacity. Since they are highly vulnerable to anthropogenic activities, they have been selected for the Marine Strategy Framework Directive (MSFD) monitoring programs. The pressure and impact of fishing gear and marine litter on these species were evaluated through the image analysis of 54 remotely operated vehicle (ROV) routes along the Campania coasts (Tyrrhenian Sea, Italy). CSS density was calculated as the number of colonies/100 m2. Anthropogenic pressure was estimated as the frequency of frames showing longline, nets, other gear, plastic objects, metal objects, and other litter; while the impact was expressed as the frequency showing necrosis/epibiosis, broken/upturned and covered/entangled colonies. Cnidaria dominate in the Napoli, Campanella and Capri areas, while Bryozoa dominate in Cilento N and Cilento S areas. Campanella and Capri appeared to be the least heterogeneous despite their higher CSS densities, which was possibly related to the dominance of a few species. These areas were the most affected by showing the highest numbers of fishing gear (longlines) and marine litter (metal objects) recorded, amongst which longlines are the most abundant. In addition, these fishing areas are either close to a large urban center or located along popular touristic routes. In all the areas, colonies with necrosis/epibiosis (CNE) impact are present with low-moderate values, while the category gears covering/entangling (GCE) impact prevails in the Campanella and Capri areas, and this is strictly connected to the high presence of fishing gear.

New insights into the structure and function of the prokaryotic communities colonizing plastic debris collected in King George Island (Antarctica): Preliminary observations from two plastic fragments

In Antarctic regions, the composition and metabolic activity of microbial assemblages associated with plastic debris ("plastisphere") are almost unknown. A macroplastic item from land (MaL, 30 cm) and a mesoplastic from the sea (MeS, 4 mm) were collected in Maxwell Bay (King George Island, South Shetland) and analyzed by Fourier transform infrared spectroscopy in attenuated total reflectance geometry (FTIR-ATR), which confirmed a polystyrene foam and a composite high-density polyethylene composition for MaL and MeS, respectively. The structure and function of the two plastic-associated prokaryotic communities were studied by complementary 16S ribosomal RNA gene clone libraries, total bacterioplankton and culturable heterotrophic bacterial counts, enzymatic activities of the whole community and enzymatic profiles of bacterial isolates. Results showed that Gamma- and Betaproteobacteria (31% and 28%, respectively) dominated in MeS, while Beta- and Alphaproteobacteria (21% and 13%, respectively) in MaL. Sequences related to oil degrading bacteria (Alcanivorax,Marinobacter) confirmed the known anthropogenic pressure in King George Island. This investigation on plastic-associated prokaryotic structure and function represents the first attempt to characterize the ecological role of plastisphere in this Antarctic region and provides the necessary background for future research on the significance of polymer type, surface characteristics and environmental conditions in shaping the plastisphere.

Critical review on microplastics in fecal matter: Research progress, analytical methods and future outlook

There has been an ever-increasing attention over years for investigating microplastics in feces of lower to higher trophic organisms from diverse environments. Focusing on the standardization of methodologies for reliable generation and comparison of data is one of the important aspects in microplastic area. This first review, comprising 20 studies in total, critically summarizes and compares the methodological approaches for the determination of microplastics in feces as well outlines the levels and characteristics of microplastics detected in feces worldwide. Contaminations and QA/QC measures are also discussed. Despite variations among the approaches, most studies (n = 12) described herein rely on the digestion processes involving H₂O₂ (n = 7) and KOH (n = 6) for the separation of microplastics, whereas very few included wet sieving (n = 5), density separation using NaCl (n = 3) and NaI (n = 1) and enzymatic digestion (n = 2). Microscopical sorting and spectroscopic methods such as infrared and Raman were combined for identification and characterization of microplastics. The detected microplastics varied by size, shape, color and polymer types and the differences in reporting units of microplastic abundance make comparison across studies difficult. Taking advantage of the current knowledge, our review identified analytical challenges and suggested appropriate methods on research into microplastic contamination in feces. This work will serve as a valuable information of available analytical methods for examining microplastics in feces and will stimulate further research to advance our understanding of microplastics from feces.

The dynamics of microplastics and associated contaminants: Data-driven Lagrangian and Eulerian modelling approaches in the Mediterranean Sea

Plastic pollution is widespread in the global oceans, but at the same time several other types of hydrophobic pollutants contaminate the marine environment. As more and more evidence highlights, microplastics and polluting chemicals are intertwined via adsorption/desorption processes. A thorough assessment of their total impact on marine ecosystems thus requires that these two kinds of pollution are not considered separately. Here we compare the outcomes of two complementary, data-driven modelling approaches for microplastic dispersal and for Plastic-Related Organic Pollutants (PROPs) in the marine environment. Focusing on the Mediterranean Sea, we simulate two years of Lagrangian particle tracking to map microplastic dispersion from the most impacting sources of pollution (i.e. coastal areas, the watersheds of major rivers, and fishing activities). Our particle sources are data-informed by national census data, hydrological regimes, and vessel tracking data to account for spatial and temporal variability of mismanaged plastic waste generation. These particle-based simulations are complemented with a simulation of the dynamics of primary pollutants in the sea, obtained via an advection-diffusion Eulerian model. While providing further understanding of the spatiotemporal distribution of microplastics and the dynamics of PROPs at a Mediterranean-wide scale, our results call for the development of novel integrated modelling approaches aimed at coupling the dynamics of microplastics with the chemical exchanges occurring through them, thus promoting a holistic description of marine plastic pollution.

Microplastics removal efficiency of drinking water treatment plant with pulse clarifier

Microplastics are recognized as ubiquitous pollutants in aquatic environments; however, very little study is done on their occurrence and fate at drinking water treatment plants (DWTPs). Though, the toxic effect of microplastics on human health is not yet well established; there is global concern about their possible ill effect on the human. Hence, the present study evaluates the occurrence of microplastics at different treatment stages of a typical DWTP with pulse clarification and its removal efficiency. In the test DWTP, raw water, sourced from river Ganga, was found to contain microplastics 17.88 items/L. Cumulative microplastic removal at key treatment stages viz. pulse clarification and sand filtration was found to be 63% and 85%, respectively. The study also revealed higher microplastic abundance on the sand filter bed due to the screening effect. The most frequently occurring microplastics were fibers and films/fragments with polyethylene terephthalate and polyethylene as a major chemical type. The t-distributed stochastic neighbor embedding machine learning algorithm revealed a strong association between microplastic abundance with turbidity, phosphate and nitrate. The test DWTP with a pulse clarification system was having comparable microplastics removal efficiency with previously reported advanced DWTPs.

Analysis of the Gastro-Intestinal Tract of Marine Mammals: A Multidisciplinary Approach with a New Multi-Sieves Tool

Simple Summary

Currently procedures used to obtain samples from the gastro-intestinal tract (GIT) and protocols used to perform their respective analyses do not allow a multidisciplinary approach of this system. In fact, the investigations applied on the GIT, when performed singularly, could impair or limit the other analyses, because the currently procedures do not consider the needs of other disciplines. This means that the analyses to perform must be selected a priori, sacrificing the collection of other types of data and leads to the risk of losing important information, especially for wildlife species. To solve this conflict, we implement and standardize a new methodological approach to the GIT of marine mammals, which allow the collection of samples for different disciplines at the same time, performing the respective analyses, interpret and compare their results in a multidisciplinary way. The compatibility of multiple analyses allows the gaining of more information about the cause of death of stranded marine mammals and to enhance the knowledge of their biology and ecology.

Abstract

Organs and content of the gastro-intestinal tract (GIT) of marine mammals are relevant for a variety of investigations and provide data to researchers from different fields. Currently used protocols applied to the GIT for specific analysis limit the possibility to execute other investigations and important information could be lost. To ensure a proper sample collection and a multidisciplinary investigation of the GIT of marine mammals, a new multi-sieves tool and a specific protocol have been developed. This new device and approach allowed the simultaneous sampling of the GIT and its content for the main investigations concerned. The samples collected during these preliminary trials were suitable to perform all the different research procedures considered in this work. The obtained results show that with a few and easy procedural adjustments, a multidisciplinary sampling and evaluation of the GIT of marine mammals is possible. This will reduce the risk of losing important data aimed at understanding the cause of death of the animal, but also biology and ecology of marine mammals, and other important data for their conservation and habitats management.

Are microplastic particles a hotspot for the spread and the persistence of antibiotic resistance in aquatic systems?

In the last decade, the study of the origin and fate of plastic debris received great attention, leading to a new and broad awareness of the hazard represented by these particles for the environment and the biota. At the same time, the scientific consideration on the leading role of the environment regarding the spread of antibiotic resistant bacteria (ARB) increased. Both, microplastic particles (MPs) and ARB share pollution sources and, in aquatic systems, MPs could act as a novel ecological niche, favouring the survival of pathogens and ARB. MPs can host a specific microbial biofilm, referred to as plastisphere, phylogenetically different from the surrounding planktonic microbial community and from the biofilm growing on other suspended particles. The plastisphere can influence the overall microbiome of a specific habitat, by introducing and supporting different species and by increasing horizontal gene transfer. In this review we collect and analyse the available studies coupling MPs and antibiotic resistance in water, highlighting knowledge gaps to be filled in order to understand if MPs could effectively act as a carrier of ARB and antibiotic resistance genes, and pose a real threat to human health.

Functional interplay between plastic polymers and microbes: a comprehensive review

Escalated production of plastic, their worldwide distribution and persistent nature finally results into their environmental accumulation causing severe threats to the ecological environment and biotic health. Thus, development of suitable measurements for environmental remediation of plastic may be an urgent issue in this plastic age. Some recent reviews have categorized the microbial species able to degrade different plastic polymers and the different factors effecting bio-degradation of plastic are poorly understood. This review comprehensively discusses bio-degradation of traditional and biodegradable plastic polymers both in natural and biological environment (gut microbes and fungi) to understand different factors regulating their degradation, and also shows how degradation of plastic polymers under abiotic factors influence subsequent biological degradation. Different physicochemical modifications like - breaking large polymers into small fragments by pre-treatment, functional groups enrichment, identifying potent microbial species (consortia) and engineering microbial enzymes might be crucial for bio-degradations of plastic. Effects of micro/nanoplastic and other chemical intermediates, formed during the bio-degradation of plastic, on species composition, abundance, growth, metabolism and enzymatic systems of microbes involved in the bio-degradation of plastic should be determined in future research.

Coastal ecosystem inventory with characterization and identification of plastic contamination and additives from aquaculture materials

In the early 1970s, studies of marine litter first appeared in the scientific literature. Fifty years later, knowledge of several coastal areas of the Atlantic, the driving forces of oyster farmers and aquaculture, is lacking. This work documents a pilot study on an Atlantic coastal area (France). This study aims to (i) characterize the abundance of macroplastics related to aquaculture tools; (ii) microplastics present in beach sediments and (iii) characterization of pollutants present on aquaculture plastics collected. First, it was observed that 70% of the plastics collected on the beach were characteristic of aquaculture materials. In sediments, MPs most found were Polyamide between 10 and 20 μm, with a total MP concentration of 397-457 MPs.kg^-1. Pipes collectors (PVC), frequently used in aquaculture, have been shown to have concentrations of dimethylphthalates and naphthalene. Waste management and support policies can then base their actions on such studies, in order to improve their knowledge.

A review: Research progress on microplastic pollutants in aquatic environments

The ubiquitous problems of microplastics in waters are receiving global attention as microplastics can harm aquatic organisms, and finally can accumulate in the human body through biological chain amplification. In addition, microplastics act as a carrier capable of carrying heavy metals, organics, which form complex pollutants. These new combinations of pollutants, once ingested by aquatic organisms, are amplified through the food chain and can have unpredictable ramifications for aquatic organisms and human beings. Therefore, human beings are not only the source of plastic pollution, but also the sink of microplastic pollution. Therefore, this study reviews the source and distribution of microplastics, and their combined ability with heavy metals, antibiotics, and persistent organic pollutants in aquatic environments. Furthermore, it describes the interaction between aquatic organisms and microplastics. Finally, some suggestions are put forward to promote the sustainable application of microplastics. This work provides theoretical guidance for combining microplastics with other pollutants in water, and the accumulation of microplastics in food chain.

Microplastics with adsorbed contaminants: Mechanisms and Treatment

Plastic pollution has been a significant and widespread global issue, and the recent COVID-19 pandemic has been attributed to its worsening effect as plastics have been contaminated with the deadly infectious virus. Microplastics (MPs) may have played a role as a vector that carries hazardous microbes such as emerging bacterial threats (i.e. antibiotic resistant bacteria) and deadly viruses (e.g., coronavirus); this causes great concern over microplastics contaminated with emerging contaminants. Mitigation and treatment of MPs are challenging because of a range of factors including but not limited to physicochemical properties and composition of MPs and pH and salinity of the solution. Despite the heterogeneous nature of aquatic systems, research has overlooked interactions between contaminants and MPs under environmental conditions, degradation pathways of MPs with adsorbed contaminants, and, especially, the role of adsorbed contaminants in the efficiency of MP treatment through membrane filtration, in comparison with other treatment methods. This review aims to (1) analyze an assortment of factors that could influence the removal of MPs and mechanisms of contaminant adsorption on MPs, (2) identify mechanisms influencing membrane filtration of MPs, (3) examine the fate and transport of MPs with adsorbed contaminants, (4) evaluate membrane filtration of contaminant-adsorbing MPs in comparison to other treatment methods, and (5) draw conclusions and the future outlook based on a literature analysis.

Investigation on the adsorption and desorption behaviors of heavy metals by tire wear particles with or without UV ageing processes

In recent years, tire wear particles (TWP), as the significant proportion of microplastics (MPs), has adsorbed much attention due to its widespread presence in aquatic ecosystem. Compared with typical MPs, TWP exists significant differences in composition, additives, characteristics and so on. With TWP and polypropylene (PP) as target MPs, Cd²⁺ and Pb²⁺ as target pollutants, the adsorption-desorption characteristics of heavy metal ions on original and aged MPs were studied. Compare with the PP, the S_BET of TWP increased more significantly after the UV ageing process. Meanwhile, the zeta potential of TWP increased from -8.01 to -14.6 mV and PP from -5.36 to -9.52 mV, and the surface of the TWP were more negatively-charged. In addition, the hydrophilicity of MPs enhanced due to the increased oxygen-containing functional groups after ageing process. Compared with PP, the physicochemical properties of TWP changed more obviously during UV ageing processes. The adsorption results showed that the pseudo-second-order model could better describe the adsorption processes of Cd²⁺ and Pb²⁺ on MPs. Meanwhile, the orders of adsorption capacity of MPs for Cd²⁺ and Pb²⁺ were aged TWP > aged PP > original TWP > original PP. The phenomenon of adsorption confirmed that TWP had better vector effects for heavy metal ions than PP, and the ageing processes could enhance the adsorption capacity of MPs. Moreover, the desorption results demonstrated that, compared with PP, the TWP (with higher adsorption capacity) also had the better desorption capacity for heavy metal ions in simulated gastric fluid. Compared with PP, the TWP might cause a more serious hazard to aquatic environment and organisms. These investigations would contribute to assessing the potential environmental and biological risk of TWP, especially considering the effect of the ageing process.

Cohabiting with litter: Fish and benthic assemblages in coastal habitats of a heavily urbanized area

Anthropogenic litter negatively impacts the marine environment and threatens biodiversity. At the same time, it represents a suitable substrate for the settlement of sessile species, thus potentially altering composition and structure of soft bottom benthic assemblages. By using a Remotely Operated Vehicle (ROV), we hereby investigated patterns of abundance, distribution, and origin of benthic litter in three subtidal habitats of a heavily urbanized area and tested whether litter distribution related to patterns of fish and mega- and macro-benthic diversity. Litter accumulation mostly occurred on soft bottoms, while rocky substrata were the least affected, albeit being particularly threatened by sea-based pollution. As expected, the highest biodiversity was observed on rocky bottoms, hosting notable biogenic formations (Cladocora caespitosa, Leptogorgia sarmentosa) despite the area is historically affected by anthropogenic activities. No correlation was found between biota and marine litter, suggesting that litter does not apparently influence biodiversity and distribution of the investigated assemblages.

Microplastics act as vectors for antibiotic resistance genes in landfill leachate: The enhanced roles of the long-term aging process

Microplastics (MPs) are found to be ubiquitous and serve as vectors for other contaminants, and the inevitable aging process changes MP properties and fates. However, whether the MPs in aging process affects the fates of antibiotic resistance gene (ARGs) in aquatic environments is poorly understood. Herein, the physicochemical property alteration of MPs being aged in landfill leachate, an important reservoir of MPs and ARGs, was investigated, and microbial community evolution and ARGs occurrence of MP surface during the aging process were analyzed. Aging process remarkably altered surface properties, including increasing specific surface areas, causing the formation of oxygen-containing groups, and changing surface morphology, which further increased the probability of microbial colonization. The bacterial assemblage on MPs showed higher biofilm-forming and pathogenic potential compared to leachate. ARGs quantification results suggested that MPs exhibited selective enrichment for ARGs in a ratio of 5.7-10³ folds, and the aging process enhanced the enrichment potential. Further co-occurrence networks suggested that the existence of non-random, closer and more stable ARGs-bacterial taxa relations on MP surface affected the ARG transmission. The study of ARG partitioning on MPs indicated that extracellular DNA was a nonnegligible reservoir of ARGs attached on MP surface, and that biofilm bacterial community influenced ARGs partitioning pattern during the aging process. This study confirmed that the aging process could enhance the potential of MPs as vectors for ARGs, which would promote the holistic understanding of MP behavior and risk in natural environments.

Microplastics physicochemical properties, specific adsorption modeling and their interaction with pharmaceuticals and other emerging contaminants

This review discusses the imminent threat that microplastics (MPs) associated with pharmaceuticals represent to the aquatic environment and public health. We initially focused upon recognizing and stressing that MPs are ubiquitous pollutants. The influence of environmental factors, such as pH, mechanical stress, and photodegradation, are examined, aiming to elucidate how both substances might associate, what are their simultaneous degradation pathways and, to understand the interactions between MPs and pharmaceuticals. Mathematical tools, such as modeling and simulations, are presented in detail, aiming to improve how information is interpreted. Furthermore, it is exhibited that MPs sorption and interaction behavior towards organic contaminants play an important role in understanding its dynamics in the environment, as well as their possible interactions with pharmaceuticals that are summarized. At last, MPs and pharmaceuticals toxicity and bioaccumulation are presented.

Microplastics aggravate the joint toxicity to earthworm Eisenia fetida with cadmium by altering its availability

Microplastics (MPs) have become a global environmental issue, however, the threats of metal-associated MPs to soil ecosystems and their involved processes have not been fully disclosed. In this study, a microcosm experiment with co-exposure of polyethylene and cadmium was conducted to determine their joint effects on the earthworm Eisenia fetida and to explore their relationship with the soil Cd availability that affected by MPs. The results showed that 28-day co-exposure of MPs and Cd significantly induced higher avoidance responses, weight loss and reduced reproduction of earthworms with the increasing content of pollutants. MPs and Cd jointly inhibited the superoxide enzyme (SOD) and peroxidase (POD) activities while increasing the glutathione (GSH) and malondialdehyde (MDA) activities in E. fetida. Histopathological changes and DNA damage to earthworm sperm also occurred in an MPs-dose-dependent manner. In addition, the presence of MPs significantly increased the soil diethylenetriaminepentaacetic acid (DTPA)-Cd concentrations by 1.20-fold and 1.43-fold while increasing the Cd bioaccumulation in E. fetida by 2.65-fold and 1.42-fold in low- and high-Cd-contaminated soil, respectively, which potentially contributed to the aggravation of the joint toxicity to E. fetida. In conclusion, this study demonstrated that microplastics could enhance the cadmium availability in the co-exposure soil which resulted in the joint toxicity of metal-associated MPs to soil organisms. CAPSULE: MPs increased soil Cd availability and potentially aggravated the joint toxicity with Cd to Eisenia fetida.

Critical evaluation of biodegradation studies on synthetic plastics through a systematic literature review

Increasing amounts of plastic waste in the environment and their fragmentation into smaller particles known as microplastics (particles, <5mm) have raised global concerns due to their persistency in the environment and their potential to act as vectors for harmful substances or pathogenic microorganisms. One possible solution to this problem is biodegradation of plastics by microorganisms. However, the scientific information on plastic-degrading microorganisms is scattered across different scientific publications. We conducted a systematic literature review (SLR) with predefined criteria using the online databases of Scopus and Web of Science to find papers on bacterial biodegradation of synthetic petroleum-based polymers. The aims of this SLR were to provide an updated list of all of the currently known bacteria claimed to biodegrade synthetic plastics, to determine and define the best methods to assess biodegradation, to critically evaluate the existing studies, and to propose directions for future research on polymer biodegradation in support of more rapid development of biodegradation technologies. Most of the bacteria identified here from the 145 reviewed papers belong to the phyla Proteobacteria, Firmicutes and Actinobacteria, and most were isolated from contaminated sites, such as landfill sites. Just under a half of the studies (44%) investigated the biodegradability of polyethylenes and derivates, particularly low-density polyethylenes. The methods used to monitor the biodegradation were mainly scanning electron microscopy and Fourier-transform infrared spectroscopy. We propose that: (1) future research should focus on biodegradation of microplastics arising from the most common pollutants (e.g. polyethylenes); (2) bacteria should be isolated from environments that are permanently contaminated with plastics; and (3) a combination of different observational methods should be used to confirm bacterial biodegradation of these plastics. Finally, when reporting, researchers need to follow standard protocols and include all essential information needed for repetition of the experiments by other research groups.

Microplastic's story

The problem of microplastic pollution is now the order of the day in front of everyone's eyes affecting the environment and the health of leaving creature. This work aims to retrace the history of microplastics in a critical way through a substantial bibliographic collection, defining the points still unresolved and those that can be resolved. Presence of marine litter in different environments is reviewed on a global scale, focusing in particular on micro and macro plastics definition, classification and characterization techniques.

The dynamics of plastic pellets on sandy beaches: A new methodological approach

Plastic found in the coastal zone is a result of waste mismanagement. This material comes directly from offshore disposal or by fishing debris, other marine activities, and by marine currents and winds, as well as urban drainage systems and estuaries. Specifically, in the case of plastic pellets, which are spheres with 2-5 mm that constitute the raw material for the manufacture of plastic products, the Santos Port and the plastic factories in Cubatão city (Brazilian southeastern coast), are considered the main local sources for the São Paulo state coast. Consequently, the beaches most affected by this pollutant are those near Santos estuary, like Enseada do Guarujá beach. However, some questions are still open, such as: what are the mechanisms which control the pellets deposition, and which locations are most favorable for deposition on the beach? To answer these questions, a four-step research was carried out at Enseada beach: 1) Plastic pellets geodetic survey based on GNSS positioning; 2) Beach geomorphometric parameters (altitude, aspect, and slope) derived by Digital Elevation Model (DEM); 3) Strandline altitude estimated through wave climate and tide height; and, 4) Plastic pellets deposition Suitability Index (PSI). The joint analysis of the altimetric, geomorphometric and meteoceanographic aspects showed that the beach areas with altitudes higher than those calculated for the strandline (>2.06 m), slope ~ 3° and facing the same direction of the higher energy waves (157.5-202.5°) were more susceptible to pellet deposition. This indicates that the accumulation of this pollutant on the beach is controlled not only by its physical characteristics, but mainly by storm surge events. Besides, surveys with geodetic reference (fixed, univocal, and relatively stable on time) bring up altimetric information as a result of all interactions and can be compared with other beaches anywhere on the planet - thus contributing to a standardization of the survey methodology.

Joint effects of microplastic and dufulin on bioaccumulation, oxidative stress and metabolic profile of the earthworm (Eisenia fetida)

Microplastics and pesticides are identified as two environmental pollutants that have an adverse impact on the environment. The knowledge about the combined exposure of pesticides and microplastics may facilitate further assessment of their ecotoxicity. In this study, we investigated joint effects of microplastic and dufulin on bioaccumulation, oxidative stress and metabolic profile of the earthworm. Bioaccumulation analysis showed that the bio-soil accumulation factor of dufulin in earthworms reached its maximum value on the 14th day, and microplastics could significantly increase the bioaccumulation of dufulin in earthworms. Biochemical analysis showed that the oxidative damage of earthworms could be observed on the 14th day of the exposure to dufulin, while the oxidative damage of earthworms could be observed on the 7th day of the combined exposure to microplastics and dufulin, and it could still be observed on the 14th day. ¹H-NMR-based metabolomics revealed that the exposure of dufulin significantly altered the relative abundances of 14 metabolites and two metabolic pathways, but the combined exposure of dufulin and microplastics significantly changed the relative abundances of 21 metabolites and three metabolic pathways. It could be seen that microplastics could aggravate the oxidative damage and the interference with the metabolic profile caused by dufulin to earthworms. The results of this study could provide effective information for the risk assessment of dufulin and microplastic in environmental safety.

Microplastics in soils: A review of methods, occurrence, fate, transport, ecological and environmental risks

The global prevalence of microplastics (MPs) poses a potential threat and unpredictable risk to the function and health of environmental systems. However, the research progress of soil MPs is restricted by the inherent technical inconformity and difficulties in analyzing particles in complex matrices. Here, we reviewed a selection of papers and then extrapolated a tentative standardized method for such analyses. The multiple sources of soil MPs in soil need to be quantified. Global monitoring data of soil MPs is far from sufficient. The interaction between MPs and different properties and environmental factors controls the migration and retention of MPs in soil. The migration behavior and key mechanisms of MPs in real-world environments remain to be determined. The presence of MPs threatens soil microbial-plant-animal ecosystem function and health, and may enter the human body through the food chain, although the extent of these hazards is currently debated. In particular, attention should be paid to the potential transport and ecotoxicological mechanisms of contaminants derived and adsorptive from MPs and of harmful microorganisms (such as pathogens) attached as biofilms. Although there exist preliminary studies on soil MPs, it is urgent to consider the diversity of MPs as a suite of contaminants and to systematically understand the sources, flux and effects of these artificial pollutants in time and space from the perspective of plastic environmental cycle. More comprehensive quantification of their environmental fate is undertaken to identify risks to global human and ecological systems. From the perspective of controlling soil MP pollution, the responsibility assignment of government manage-producer-consumer system and the strategy of remediation should be implemented. This review is helpful for providing an important roadmap and inspiration for the research methods and framework of soil MPs and facilitates the development of waste management and remediation strategies for regional soil MP contamination.

Microplastics in corals: An emergent threat

This article seeks to present a summary of knowledge and thus improve awareness of microplastic impacts on corals. Recent research suggests that microplastics have a variety of species-specific impacts. Among them, a reduced growth, a substantial decrease of detoxifying and immunity enzymes, an increase in antioxidant enzyme activity, high production of mucus, reduction of fitness, and negative effects on coral-Symbiodiniaceae relationships have been highlighted in recent papers. In addition to this, tissue necrosis, lower fertilization success, alteration of metabolite profiles, energetic costs, decreased skeletal growth and calcification, and coral bleaching have been observed under significant concentrations of microplastics. Furthermore, impairment of feeding performance and food intake, changes in photosynthetic performance and increased exposure to contaminants, pathogens and other harmful compounds have also been found. In conclusion, microplastics may cause a plethora of impacts on corals in shallow, mesophotic, and deep-sea zones at different latitudes; underlining an emerging threat globally.

Review of current trends, advances and analytical challenges for microplastics contamination in Latin America

Microplastics accumulation is an emerging environmental issue and a threat to marine life and human health. There is a growing number of investigations on the abundance and distribution of microplastics in different water bodies and biota worldwide, with relatively few studies conducted in Latin America, however, the current knowledge of microplastics sources, occurrence, transport, fate and potential impacts remains largely unexplored. This review presents the current trends and advances of microplastics on a lesser known region of the world by compiling the research performed to date in different environmental compartments. The sampling techniques and methods for microplastics extraction in the existing literature data are also summarized. Among 78 published studies reviewed, 34% of studies were from Brazil and 46% of studies have mainly focused on biota. The main findings showed that microplastics are not negligible across Latin America significantly varying in their distribution, with the prevalence of fibers comprising 62% of the total. Polyethylene, polypropylene, polyethylene terephthalate and polystyrene have been identified as the most common polymer types, accounting for 80% of the total. Limited studies and lack of standardized methodologies render difficulties to establish fundamental information on microplastics abundance and types in most countries of this region. Therefore, this review will primarily serve as a baseline when evaluating the environmental relevance of microplastics in Latin America and would stimulate discussions focusing on this topic, calling for more research in future.

Effects of co-loading of polyethylene microplastics and ciprofloxacin on the antibiotic degradation efficiency and microbial community structure in soil

Microplastics (MPs) have become a global environmental concern while soil plastic pollution has been largely overlooked. In view of the severe antibiotic contamination in arable soils owing to land application of sewage sludge and animal manure, the invasion of MPs along with antibiotics may pose an unpredictable threat to soil microbial communities and ecological health. In this work, polyethylene MPs and ciprofloxacin (CIP) were applied to a soil microcosm to investigate the CIP degradation behavior and their combined effects on soil microbial communities. Compared with that of the individual amendment of CIP, the co-amendment of CIP and MPs reduced the CIP degradation efficiency during the 35 d cultivation period. In addition, the high-throughput sequencing results illustrated that the combined loading of MPs and CIP in soil significantly decreased the microbial diversity compared with that of individual contamination. As for the community structure, the microbial compositions at the phylum level were consistent among all treatments, and the most dominant phyla were Proteobacteria, Actinobacteria, and Chloroflexi. At the genus level, only one genus, namely Arthrobacter, was remarkably changed in the CIP-amended soil compared with that in the blank control, but four genera were significantly altered in the MPs-CIP co-amended soil. Serratia and Achromobacter were abundant in the combined polluted soil, which might have been involved in accelerated depletion of soil total nitrogen based on redundancy analysis. These findings may contribute to the understanding of bacterial responses to the combined pollution of MPs and antibiotics in soil ecosystems.

Approaching the environmental problem of microplastics: Importance of WWTP treatments

The undeniable presence of microplastics (MPs) in soil, air and, especially, in the aquatic environment has revealed them to be an emerging pollutant. One of the main sources contributing to the release of these microplastics into the environment is wastewater treatment plants (WWTPs). During the treatment of wastewater, these microparticles undergo incomplete retention, which leads to their discharge in huge amounts into water masses. The microplastics removed from the wastewater during the treatment processes usually become entrained in the sewage sludge, which is commonly employed as organic fertilizer. Alarming data regarding the occurrence of MPs in nature and the increasing public awareness of environmental concerns have led to the appearance of numerous studies on this topic in recent years. So, this work is focused on providing an overview of available processes for the removal of microplastics from water and also from sediments. Social demand for the correct and effective management of microplastics is constantly increasing and should be given careful consideration before future action is taken. Recycling is a good option, and policies might be developed in this direction, moving towards a circular and sustainable economy for plastics.

An overview of recent advances in micro/nano beads and microfibers research: Critical assessment and promoting the less known

Uptake and toxicity of microplastics (<5 mm) on organisms has merited substantial attention from scientific and research communities. Micro- (1-5000 μm) and nano- (<1 μm) beads have been recognized as promising polymeric particles globally to assess risks for organisms after ingestion. Microfibers (<5 mm) are abundant worldwide, but studies demonstrating their impacts on organisms are only emerging and remain poorly understood. The goal of this review is to facilitate the research of microfibers towards risk assessments and understanding of their health effects on organisms. This paper examines the abundance, size, shapes, colors, and polymer types of micro/nano beads and microfibers in different environments as well as summarizes the existing knowledge related to the potential effects on organisms demonstrated from laboratory-based studies. It therefore also reviews and compares current methodologies used to synthesize microfibers for ingestion studies and further, documents their effects on organisms, critically assessing the knowledge gaps that need urgent attention in this rapidly developing research field. Taking together, this article will be useful to the microplastic scientific community and provide helpful referential information to those currently engaged in this field.

Marine Plastics from Norwegian West Coast Carry Potentially Virulent Fish Pathogens and Opportunistic Human Pathogens Harboring New Variants of Antibiotic Resistance Genes

To our best knowledge this is the first study characterizing fish pathogens isolated from marine plastics from the West coast of Norway for their potential for pathogenicity using whole genome sequencing. Marine plastic polymers identified as polyethylene, polyethylene/ethylene vinyl acetate copolymer and polypropylene, yielded a total of 37 bacterial isolates dominated by Pseudomonas spp. (70%). Six isolates representing either fish pathogens or opportunistic human pathogens were selected for whole genome sequencing (WGS). These included four isolates belonging to Aeromonas spp., one Acinetobacter beijerinckii isolate and one Morganella morganii isolate. Three Aeromonas salmonicida isolates were potentially virulent and carried virulence factors involved in attachment, type II and type VI secretion systems as well as toxins such as aerA/act, ahh1, ast, hlyA, rtxA and toxA. A. salmonicida and Acinetobacter beijerinckii carried new variants of antibiotic resistance genes (ARGs) such as β-lactamases and chloramphenicol acetyltransferase (catB), whereas Morganella morganii carried several clinically relevant ARGs. Our study shows that marine plastics carry not only potentially virulent fish pathogens but also multidrug resistant opportunistic human pathogens like M. morganii and may serve as vectors for transport of these pathogens in the marine environment.

Risk assessment of added chemicals in plastics in the Danish marine environment

A risk assessment framework for direct exposure of residual additives and monomers present in ingested plastic particles, including microplastics, in the Danish marine environment, was presented. Eight cases of different polymer types and product groups were defined that represent the most significant exposures, and thus potential high-risk cases, towards marine organisms. Risk Quotients (RQ) were calculated for three trophic levels, i.e. pelagic/planktonic zooplankton: copepod, benthopelagic fish: Atlantic cod and seabird: northern fulmar. European and Danish Environmental Quality Standard (EQS) values were used as Predicted No-Effect Concentrations (PNEC). RQ larger than unity, indicating potential risks, were found for copepod and cod (pelagic community) and the flame-retardant pentabromodiphenyl ether (PeBDE) used in polyurethane (PUR), the biocide tributyltin (TBT) present as impurity in polyvinylchloride (PVC) and PUR, and the flame-retardant hexabromocyclododecane (HBCDD) used in expanded polystyrene (EPS). A potential risk was found for fulmar (secondary poisoning) and PeBDE used in PUR.

The removal of microplastics in the wastewater treatment process and their potential impact on anaerobic digestion due to pollutants association

Microplastics are abundant in municipal wastewater which is mainly from personal care products and laundry. In recent years, great attention has been given to microplastics removal in wastewater treatment. In this article, the study focusing on microplastics in wastewater has been evaluated with VOSviewer. It was found that the major interest was in identification, quantification and pollution of the microplastics in the wastewater, and their transportation and final destination during wastewater treatment processes. The major microplastics and their shapes in wastewater were reviewed. Our evaluation results were consistent with other reported that fibers and fragment were the majority in terms of shape and polyethylene terephthalare (PET), polyethylene (PE), polypropylene (PP), and polystyrene (PS) are the most presented microplastics in wastewater. During wastewater treatment, the removal route of microplastics from wastewater includes settling, adsorption, entrapment, interception, etc. It confirms that microplastics are just simply transferred from wastewater to sludge. It could then bring problems to anaerobic digestion as microplastics are great vector for toxic substances such as antibiotics and persistence organic pollutants. The key to determine the microplastics effect on anaerobic digestion is the desorption behavior of the toxic substances such as antibiotics, persistent organic pollutants and heavy metals from microplastics in digestion condition. Toxic compounds which are commonly presenting in sludge have shown the tendency to release from microplastics. It indicates that microplastics in sludge have great possibility to impact on methane production.

Bioremediation as a promising strategy for microplastics removal in wastewater treatment plants

Microplastics (MPs) attract ever-increasing attention due to environmental concerns. Nowadays, they are ubiquitous across ecosystems, and research demonstrates that the origin is mainly terrestrial. Wastewater treatment plants (WWTPs) are a major source of MPs, especially fibres, in water masses. This review is focused on understanding the evolution and fate of microplastics during wastewater treatment processes with the aim of identifying advanced technologies to eliminate microplastics from the water stream. Among them, bioremediation has been highlighted as a promising tool, but confinement of microorganisms inside the WWTP is still a challenge. The potential for MPs bioremediation in WWTPs of higher aquatic eukaryotes, which offer the advantages of low dispersion rates and being easy to contain, is reviewed. Animals, seagrasses and macrophytes are considered, taking into account ecoethical and biological issues. Necessary research and its challenges have been identified.

Microplastics in subsurface coastal waters along the southern coast of Viti Levu in Fiji, South Pacific

Microplastics (MPs) remain largely understudied in Small Island Developing States. This study is aimed at comparing the abundance and characteristics of MPs in rural and urban marine coastal sites located along the southern coast of Fiji's main inhabited island, Viti Levu. Collection of subsurface waters (at depth of ca. 0.6 m) was performed at seven sites via Niskin bottle. Samples were filtered over a membrane filter to extract MPs and to allow visual analysis and polymer identification by using attenuated total reflectance in Fourier transform infrared spectroscopy. Findings from this study depict widespread presence of MPs in both urban and rural sites, and show no significant differences in the four parameters studied, i.e. abundance of MP pieces (2.0 vs 1.6 MP/L, respectively), form types (dominance of fibers), size (0.5-0.9 and 1.0-1.4 mm totaling 48% of the samples), and color (blue contributing 30%, and red and black contributing 25% each). These findings challenge the common expectation of a higher MPs pollution in urban areas compared to rural areas.

Lessons learned from an intercalibration exercise on the quantification and characterisation of microplastic particles in sediment and water samples

An intercalibration exercise on the characterisation of microplastics in marine sediment and water samples was carried out among five laboratories involved in the implementation of the Marine Strategy Framework Directive (MSFD) in their country. The samples were prepared by mixing cleaned natural sediment and sea water with microplastics sets made of particles of various polymers, shapes and colours. Overall, the errors on total counts were under 25% in absolute value. The risk of non-detection and loss of particles is greater than the risk of contamination during sample analysis. Significant differences are observed among particle types. It appears difficult to obtain reliable and comparable data on the colour of microplastics. A comparison of the errors with regards to the protocols used led to recommend NaCl [1.2 g/cm³] density separation for sediment and one filtering step (200 μm). The operators' experience appears as a key factor for the quality of the results.

Preliminary Investigation of Microlitter Pollution in Low-Energy Hydrodynamic Basins Using Sabella spallanzanii (Polychaeta: Sabellidae) Tubes

Harbor basins are strategically important and heavily impacted water bodies according to the water framework directive. Due to constant traffic, variety of activities, and low-energy hydrodynamics, these areas can have high degrees of water pollution. This study reports the results of the preliminary investigation of anthropogenic microlitter (AM) pollution in a semi-enclosed basin (Civitavecchia harbor; northern Tyrrhenian Sea, Italy) using the tubes built by the polychaete Sabella spallanzanii. The visual inspection showed AM particles within the tube structure as a result of its building process. The total average AM abundance was 20.8 ± 3.7 AM g^-1. AM abundances and flushing time as the hydrodynamic parameter of water renewal highlight the homogeneity of the sampling area. The suitability of S. spallanzanii tubes as a potential tool to investigate the AM pollution level in sheltered and polluted environments is highlighted.

Toxicity of Microplastics and Nanoplastics in Mammalian Systems

Fragmented or otherwise miniaturized plastic materials in the form of micro- or nanoplastics have been of nagging environmental concern. Perturbation of organismal physiology and behavior by micro- and nanoplastics have been widely documented for marine invertebrates. Some of these effects are also manifested by larger marine vertebrates such as fishes. More recently, possible effects of micro- and nanoplastics on mammalian gut microbiota as well as host cellular and metabolic toxicity have been reported in mouse models. Human exposure to micro- and nanoplastics occurs largely through ingestion, as these are found in food or derived from food packaging, but also in a less well-defined manner though inhalation. The pathophysiological consequences of acute and chronic micro- and nanoplastics exposure in the mammalian system, particularly humans, are yet unclear. In this review, we focus on the recent findings related to the potential toxicity and detrimental effects of micro- and nanoplastics as demonstrated in mouse models as well as human cell lines. The prevailing data suggest that micro- and nanoplastics accumulation in mammalian and human tissues would likely have negative, yet unclear long-term consequences. There is a need for cellular and systemic toxicity due to micro- and nanoplastics to be better illuminated, and the underlying mechanisms defined by further work.

Marine debris ingestion and human impacts on the Pygmy sperm whale (Kogia breviceps) in southern Brazil

Pygmy sperm whales, Kogia breviceps (Kogiidae), are a small cetacean that inhabits Mesopelagic regions near the continental shelf. In this study we present record of plastic ingestion by K. breviceps in Brazil. In August 2010 on the coast of Rio Grande do Sul, a carcass was found showing evidences of interaction with fishing nets. The stomach content was collected for the analysis of food items, but the presence of four plastics weighing 55.9 g was found. In addition, the analysis of food items revealed the presence of the fish Merluccius hubbsi, which is an intensely explored species by fisheries activities in southern Brazil. Merluccius sp. is common in the diet of K. breviceps in several regions of the planet. This work shows that in southern Brazil, K. breviceps suffers intense impact of both ingestion of anthropic material and fisheries, and so must be closely monitored.