Overview of microplastics pollution with heavy metals: Analytical methods, occurrence, transfer risks and call for standardization

Potential impacts of polyethylene microplastics and heavy metals on Bidens pilosa L. growth: Shifts in root-associated endophyte microbial communities

This study investigates the impact of polyethylene (PE) microplastics of varying particle sizes and concentrations on the growth of Bidens pilosa L. and its root-associated microbial communities in cadmium (Cd) and lead (Pb) co-contaminated soil. PE microplastics had a significant impact on plant growth. Notably, at the P05-10 level, root length, root weight, and total biomass exhibited the greatest reductions by 48.9 %, 44.1 %, and 45.2 %, respectively. Furthermore, PE microplastics reduced photosynthetic pigment levels and promoted the accumulation of reactive oxygen species, as indicated by a 264.8 % and 57.2 % increase in H2O2 content in roots and leaves. High-throughput sequencing revealed substantial alterations in the composition of bacterial and fungal communities, with stress-resilient taxa such as Actinobacteria, Verrucomicrobiota, and Rhizophagus exhibiting increased relative abundance. Correlation analyses indicated that variations in soil pH and enzymatic activity influenced microbial community structure, which in turn affected plant physiological responses. Functional predictions using PICRUSt2 and BugBase suggested enhanced oxidative stress tolerance, increased secondary metabolite biosynthesis, and a higher prevalence of stress-resistant phenotypes under conditions of elevated PE concentrations and smaller particle sizes. Overall, this study provides novel insights into the potential effects of microplastics on Bidens pilosa L., particularly in its role as a hyperaccumulator, highlighting its capacity for heavy metal uptake under microplastic exposure.

Toxicity comparison of polylactic acid and polyethylene microplastics co-exposed with methylmercury on Daphnia magna

The prevalence of microplastics (MPs) in aquatic ecosystems has become a significant environmental concern due to their persistence and potential toxicity. Although bioplastics, such as polylactic acid (PLA), are promoted as eco-friendly alternatives to conventional plastics, their toxicity remains poorly understood. This study compares the toxicity and pollutant vector roles of polar PLA-derived bio-microplastics (bio-MPs) with apolar low-density polyethylene (LDPE) MPs, both individually and in combination with methylmercury (MeHg), in Daphnia magna. PLA bio-MPs, both alone and in combination with MeHg, significantly reduced survival rates and reproduction while inducing oxidative stress. Additionally, PLA bio-MPs increased Hg accumulation and negatively impacted acetylcholinesterase activity and vitellogenin gene expression compared to LDPE MPs. The findings of this study suggest that PLA bio-MPs, despite being in vivo biodegradable, may pose similar or even greater environmental risks than fossil fuel-based MPs, particularly due to their potential to enhance the bioaccumulation and toxicity of coexisting pollutants.

Effects of different microplastics on the physicochemical properties and microbial diversity of rice rhizosphere soil

Biodegradable plastics, as alternatives to conventional waste plastics, are increasingly applied across various fields. However, the ecological risks associated with the widespread use of biodegradable plastics remain unclear. Additionally, biodegradable plastics tend to age in the environment, leading to changes in their physicochemical properties. The ecological risks brought by the aging of microplastics have also been scarcely studied. In this study, we selected conventional microplastics (PE-MPs), biodegradable microplastics (PLA-MPs), and aged biodegradable microplastics (aging-PLA-MPs) to explore their effects on the rhizosphere soil environment of rice. The results showed that microplastics reduced the soil N and P content, with PE slightly increasing the DOC content, while PLA and aging-PLA significantly increased DOC by 21.13 and 24.04%, respectively. Microplastics also decreased soil enzyme activity, with aging-PLA having a somewhat stimulatory effect on enzyme activity compared to PLA. Furthermore, microplastics reduced the soil bacterial diversity index and altered the community structure of dominant bacterial species, with DOC content and FDA hydrolase being the main factors influencing the soil bacterial community. Bacteria were most sensitive to PLA, and the stability of the bacterial microbial network structure decreased, although aging reduced the negative impact of PLA on the bacterial community. This study contributes to our understanding of the ecological risks posed by biodegradable plastics and their aging processes on the environment.

Adsorption behavior of Cu(II) on UV-aged polyethylene terephthalate and polypropylene microplastics in aqueous solution

Plastics are widely used across various applications from packing to commercial products. Once discarded, they were subjected to environmental stresses, causing them to degrade into microplastics (MPs). These small, invisible pollutants pose a significant threat to aquatic ecosystems, gradually compromising the resilience and vitality of the natural environment. Moreover, MPs will act as carriers for other contaminants, for example, heavy metals (HMs). Although many studies have explored MPs and HMs independently, their combined behavior and interactions remain poorly understood. Understanding these interactions is increasingly important given rising pollution levels. MP formation and adsorption behavior are heavily influenced by factors such as UV aging, which remains unclear. In this study, both virgin and UV-aged MPs specifically PET and PP (the most widely used plastics globally) were examined in their interactions with copper (Cu2+) solutions. Surface analysis techniques such as FTIR, SEM, XRD, and AAS were employed to compare the virgin and UV-aged MPs. The results revealed that UV-aged MPs exhibited high adsorption capacities for HMs compared to virgin MPs, which can be attributed to increased pore volume and oxidative degradation. Adsorption capacity differences at various concentrations showed up to a 20% increase, with UV-aged PET MPs displaying capacities ranging from 0.6 to 3.54 mg/g. Similarly, UV-aged PP MPs showed a 15% increase in adsorption capacity ranging from 1.51 to 4.25 mg/g. The present study provided the significant evidence on the behavior of MPs adsorption and underscores the need for further research on the long-term environmental impacts of aged MPs and their interactions with pollutants.

Methodological inconsistencies and variations in environmental pollution reports: A case study of the mining-affected Geita region, Tanzania

Various studies report pollutant levels in the environment to raise awareness and call for government intervention to protect the environment and public health. However, inconsistent findings across studies complicate environmental actions and policy-making processes in many countries. Geita region in Tanzania is one of the areas with a high focus on metal pollution problems emanating from artisanal, small-scale, and industrial mining operations. This article presents a review of environmental studies conducted in the region as a case study to show the impacts of inconsistent methodological approaches resulting to varying pollutant levels of heavy metals (Hg, As, Pb, Zn and Ni) in soil, sediment, rice and water. The diversity of metal pollutant concentrations is caused by varying sample treatment methods, which result from a lack of standardised analytical methods for various pollutants within the country. For example, two different studies reported different total mercury (THg) concentrations in soil samples near the Geita gold mine: 1.89 mg/kg and 0.0625 mg/kg. Similarly, arsenic (As) levels were reported as 126.1 mg/kg and 5.5 mg/kg, while lead (Pb) concentrations varied between 23.46 mg/kg, 2.58 mg/kg, and 17.99 mg/kg in different studies of the same area. Classical analytical instruments were used in the analyses, including Atomic Absorption Spectroscopy (AAS), Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES), Energy Dispersive X-ray Fluorescence (EDXRF), and Cold Vapour Atomic Fluorescence Spectrometry (CV-AFS). However, there have been diverse sample pre-treatment methods, including sample drying techniques, sample digestion, and chemical mixture ratios, that contribute to the differences in results. Although sampling seasons and weather conditions were not reported by the different authors, they likely contributed to the observed variations. To address these discrepancies, this review suggests establishing standardised analytical methods for different pollutants to ensure uniform procedures and comparable results in the country. This standardisation would aid in effective decision-making and policy formulation to manage environmental and health risks in mining-affected and other polluted areas.

Environmental level of lanthanum increased phytoextraction of co-occurring cadmium and polystyrene nanoplastics by Sedum alfredii

Phytoextraction based on hyperaccumulators is a sustainable bioremediation technology. However, hyperaccumulators can only accumulate a single type of pollutants and need long remediation times, inhibiting simultaneous phytoextraction of co-occurring inorganic and organic pollutants. Here, the study indicated that the environmental level of lanthanum, as an emerging pollutant, was absorbed by leaves and induced endocytosis from leaves to roots (systemic endocytosis) in Sedum alfredii. Cadmium and polystyrene nanoplastics were simultaneously absorbed by root cells through systemic endocytosis, increasing the accumulation of these pollutants in Sedum alfredii. One possible mechanism of improving phytoextraction of co-occurring cadmium and polystyrene nanoplastics is that the lanthanum-induced system endocytosis increased the nutrient absorption of Sedum alfredii, thus increasing the activity of antioxidant enzymes, enhancing photosynthesis, biomass, and plant tolerance. These findings provide a new empirical basis and strategy for the simultaneous phytoremediation of co-occurring inorganic and organic pollutants in environments.

Review on the relationship between microplastics and heavy metals in freshwater near mining areas

Microplastics (MPs), degraded from plastic wastes, have drawn significant attention worldwide due to its prevalence and rapid transition. Contamination of freshwater with MPs has become an emerging global issue. Heavy metals (HMs), a prominent global pollutant, also garnered much attention due to their potential interaction with MPs, presenting a multifaceted environmental threat. The primary source of HM contamination in freshwater has been identified as mining sites. Additionally, the increasing use of plastic materials within mining areas raises concerns about MP release into the surrounding freshwater environments. Recent studies only provide information on the contamination of HMs status with MPs. However, studies on the mechanism responsible for MPs contamination from both external and internal sources of freshwater MPs and HMs are limited. The knowledge gaps in the deposition and fate of MPs in various mining situations and the possibility of combined impacts of heavy metals and MPs in the ecosystem raise ecological concerns. Here, we review the origins of MPs and HM pollution within mining sites and explore the potential combined detrimental impacts on plants and animal life. We found out that polystyrene (PS) and polyethylene (PE) have higher adsorption affinity to heavy metals, and the mingle toxic consequence of the MPs and HM can depend on the MP surface properties, pH, and salinity of the neighboring water solution. The Langmuir and Freundlich isotherm models enable the efficient design of adsorption systems. The Langmuir model describes single-layer adsorption at homogeneous sites, while the Freundlich model addresses multilayer adsorption on heterogeneous surfaces. The crucial mechanism of adsorption and desorption that underlies the occurrence of both MPs and heavy metals is a decisive matter in this issue.

Effects of particle size and aging on heavy metal adsorption by polypropylene and polystyrene microplastics under varying environmental conditions

Microplastics have become a major environmental issue because of their widespread presence and tendency to adsorb heavy metals, which can have harmful effects on aquatic ecosystems and human health. The present study investigates the adsorption mechanisms of Pb2+ and Cu2+ ions on both pristine and artificially aged microplastics (MPs) made of polystyrene (PS) and polypropylene (PP). Furthermore, the influence of MP size on the adsorption capacity under different environmental conditions was evaluated. According to the characterization of MPs, aging leads to physical damage and an increase in the number of oxygen-containing functional groups on their surface. The experimental results highlight the significantly higher adsorption ability of smaller and aged MPs compared with that of pristine MPs for both the heavy metal ions. The pseudo-second-order equation provided a better fit for the adsorption kinetics study (R2 = 0.95), suggesting that chemisorption governs the rate-limiting phase in the adsorption mechanism on the MP surfaces. The concordance between the adsorption isotherm model and Freundlich model (R2 > 0.95) indicated a predominance of multilayer adsorption. The environmental factors such as pH, humic acid, temperature, and SO42- concentration significantly affected the adsorption of Pb2⁺ and Cu2⁺ onto PP and PS MPs. These variables play a crucial role in determining the nature of the interactions between heavy metal ions and the microplastic particles under diverse environmental conditions. Electrostatic interactions, surface complexation and van der Waals forces were identified as two factors that could either improve or diminish the metal ion adsorption capacity of MPs.

Microplastic removal and risk assessment framework in a constructed wetland for the treatment of combined sewer overflows

Combined sewer overflows (CSOs) release a significant amount of pollutants, including microplastics (MPs), due to the discharge of untreated water into receiving water bodies. Constructed Wetlands (CWs) offer a promising strategy for CSO treatment and have recently attracted attention as a potential solution for MP mitigation. Nevertheless, limited research on MP dynamics within CSO events and MP removal performance in full-scale CW systems poses a barrier to this frontier of application. This research aims to address both these knowledge gaps, representing the first investigation of a multi-stage CSO-CW for MP removal. The study presents one year of seasonal data from the CSO-CW upstream of the WWTP in Carimate (Italy), evaluating the correlation of MP abundance with different water quality/quantity parameters and associated ecological risks. The results show a clear trend in MP abundance, which increases with rainfall intensity. The strong correlation between MP concentration, flow rate, and total suspended solids (TSS) validates the first flush phenomenon hypothesis and its impact on MP release during CSOs. Chemical characterization identifies acrylonitrile-butadiene-styrene (ABS), polyethylene (PE), and polypropylene (PP) as predominant polymers. The first vertical subsurface flow (VF) stage showed removal rates ranging from 40 % to 77 %. However, the unexpected increase in MP concentrations after the second free water surface (FWS) stage suggests the stochasticity of CSO events and the different hydraulic characteristics of the CW units have diverse effects on MP retention. These data confirm filtration as the main retention mechanism for MP within CW systems. The MP ecological risk assessment indicates a high-risk category for most of the water samples, mainly related to the frequent presence of ABS fragments. The results contribute to the current understanding of MPs released by CSOs and provide insights into the performance of different treatment units within a large-scale CSO-CW system, suggesting the requirement for further attention.

Local and systemic effects of microplastic particles through cell damage, release of chemicals and drugs, dysbiosis, and interference with the absorption of nutrients

Microplastic particles (MPs) have been detected in a variety of environmental samples, including soil, water, food, and air. Cellular studies and animal exposures reported that exposure to MPs composed of different polymers might result in adverse effects at the portal of entry (local) or throughout the body (systemic). The most relevant routes of particle uptake into the body are oral and respiratory exposure. This review describes the various processes that may contribute to the adverse effects of MPs. Only MPs up to 5 µm were found to cross epithelial barriers to a significant extent. However, MPs may also exert a detrimental impact on human health by acting at the epithelial barrier and within the lumen of the orogastrointestinal and respiratory tract. The potential for adverse effects on human health resulting from the leaching, sorption, and desorption of chemicals, as well as the impact of MPs on nutritional status and dysbiosis, are reviewed. In vitro models are suggested as a means of (1) assessing permeation, (2) determining adverse effects on cells of the epithelial barrier, (3) examining influence of digestive fluids on leaching, desorption, and particle properties, and (4) role of microbiota-epithelial cell interactions. The contribution of these mechanisms to human health depends upon exposure levels, which unfortunately have been estimated very differently.

Enhanced removal of microplastics from wastewater treatment plants by a novel magnetic filter

Microplastics (MPs) discharged from wastewater treatment plants (WWTPs) have emerged as serious pollutants in aquatic environments. Herein, a new magnetic filter (MFA) was prepared using an acidification-magnetization method with fly ash (FA) as the base material. The filter specifically targeted the removal of 1-μm polystyrene microspheres (PSMPs) because of the challenges they pose in filtration processes. The findings demonstrated that MFA filter exhibited superior PSMPs removal efficiency, with increases of 219%, 250%, and 288% compared to FA at flow rates of 1, 3, and 5 mL min-1, respectively. Scanning electron microscopy and other characterizations provided insights into the removal mechanisms of PSMPs using the MFA filter, which combined electrostatic attraction, π-electron conjugation, hydrogen bonding, and complexation. Environmental variables, such as solution pH, ionic strength, and dissolved organic matter, were identified as considerable influences in the removal process of PSMPs. The practical application confirmed that the MFA filter considerably promoted the elimination of MPs from the secondary treatment effluent of WWTPs without having any toxic effects on freshwater fish. Thus, this study provides a new approach to the resource utilization of FA, which would prominently promote its application prospects in MPs immobilization and removal from wastewater effluent.

Transfer from ciliate to zebrafish: Unveiling mechanisms and combined effects of microplastics and heavy metals

The impacts and toxicological mechanisms of microplastics (MPs) or heavy metals on aquatic ecosystems have been the subject of extensive research and initial understanding. However, the combined toxicity of co-pollutants on organisms and cumulative toxic effects along the food chain are still underexplored. In this study, the ciliate protozoan Paramecium caudatum and zebrafish Danio rerio were used to represent the microbial loop and the higher trophic level, respectively, to illustrate the progressive exposure of MPs and cadmium (Cd2+). The findings indicate that MPs (ca. 1 ×105 items/L) containing with Cd2+ (below 0.1 µg/L) could permeate the bodies of zebrafish through trophic levels after primary ingestion by ciliates. This could cause adverse effects on zebrafish, including alterations in bioindicators (total sugar, triglycerides, lactate, and glycogen) associated with metabolism, delayed hepatic development, disruption of intestinal microbiota, DNA damage, inflammatory responses, and abnormal cellular apoptosis. In addition, the potential risks associated with the transfer of composite pollutants through the microbial loop into traditional food chain were examined, offering novel insights on the evaluation of the ecological risks associated with MPs. As observed, understanding the bioaccumulation and toxic effects of combined pollutants in zebrafish holds crucial implications for food safety and human health.

Towards harmonization of metal(loid)s determination in conventional and compostable plastics: Comparison of acid digestion protocols in LDPE and PBAT/TPS blends

The determination of metal-containing additives in plastic materials via acid digestion protocols has attracted growing interest to address potential environmental implications. However, the lack of protocol harmonization hinders data comparability within the literature. Here, six acid digestion protocols were employed to determine the metal(loid) content in plastics: these included three different acid mixtures (HNO3 combined with H2SO4, HCl or H2O2) for microwave-assisted digestion, with or without an additional room-temperature digestion step with H2O2. Each protocol was first validated for seven metal(loid)s (As, Cd, Cr, Pb, Sb, Sn and Zn) using a low-density polyethylene (LDPE) certified reference material (ERM®-EC681m). Then, validated protocols were applied on end-use materials, including conventional (i.e., LDPE) and compostable (i.e., PBAT/TPS) plastics. The combination of H2SO4 and HNO3 with a further digestion step with H2O2 was the most suitable protocol: it successfully passed validation thresholds for all metal(loid)s (recoveries in the range 98.6-101.0 %) and yielded the highest concentrations in end-use materials. All other protocols resulted in a less efficient digestion of the sample matrix, leading to lower recoveries and the formation of solid residues. Notably, end-use plastics showed a great variability in metal(loid) concentrations, likely due to their additive-rich composition, in contrast to the minimal content of acid-soluble additives of the reference material. This study represents an initial step towards the harmonization of acid digestion protocols and highlights new challenges in accurately analyzing end-use plastic materials, due to their complex additive composition.

Sight of Aged Microplastics Adsorbing Heavy Metal Exacerbated Intestinal Injury: A Mechanistic Study of Autophagy-Mediated Toxicity Response

Contaminant-bearing polystyrene microplastics (PSMPs) may exert significantly different toxicity profiles from their contaminant-free counterparts, with the role of PSMPs in promoting contaminant uptake being recognized. However, studies investigating the environmentally relevant exposure and toxic mechanisms of aged PSMPs binding to Cr are limited. Here, we show that loading of chromium (Cr) markedly alters the physicochemical properties and toxicological profiles of aged PSMPs. Specifically, Cr-bearing aged PSMPs induced severe body weight loss, oxidative stress (OS), autophagy, intestinal barrier injury, inflammation-pyroptosis response, and enteropathogen invasion in mice. Mechanistic investigations revealed that PSMPs@Cr exacerbated the OS, resulting in intestinal barrier damage and inflammation-pyroptosis response via overactivated Notch signaling and autophagy/cathepsin B/IL-1β pathway, respectively, which ultimately elevated mortality related to bacterial pathogen infection. In vitro experiments confirmed that autophagy-mediated reactive oxygen species (ROS) overproduction resulted in severe pyroptosis and impaired intestinal stem cells differentiation alongside the overactivation of Notch signaling in PSMPs@Cr-exposed organoids. Overall, our findings provide an insight into autophagy-modulated ROS overproduction within the acidic environment of autophagosomes, accelerating the release of free Cr from PSMPs@Cr and inducing secondary OS, revealing that PSMPs@Cr is a stable hazard material that induces intestinal injury. These findings provided a potential therapeutic target for environmental MPs pollution caused intestinal disease in patients.

Micro(nano)plastic and Related Chemicals: Emerging Contaminants in Environment, Food and Health Impacts

Microplastic pollution is a problem of increasing concern in food, and while food safety issues around the world are serious, an increasing number of food safety issues related to microplastics have become the focus of people's attention. The presence of microplastics in food is a worldwide problem, and they are present in all kinds of foods, foods of both animal and plant origin, food additives, drinks, plastic food packaging, and agricultural practices. This can cause problems for both humans and the environment. Microplastics have already been detected in human blood, heart, placenta, and breastmilk, but their effects in humans are not well understood. Studies with mammals and human cells or organoids have given perspective about the potential impact of micro(nano)plastics on human health, which affect the lungs, kidneys, heart, neurological system, and DNA. Additionally, as plastics often contain additives or other substances, the potentially harmful effects of exposure to these substances must also be carefully studied before any conclusions can be drawn. The study of microplastics is very complex as there are many factors to account for, such as differences in particle sizes, constituents, shapes, additives, contaminants, concentrations, etc. This review summarizes the more recent research on the presence of microplastic and other plastic-related chemical pollutants in food and their potential impacts on human health.

Impact of microplastics on strength parameters of clayey, Sandy, silty soil: A comparative assessment

The comparative assessment of a variety of microplastic contamination on various soil types hasn't been extensively explored in existing literature. The present study focuses on the comparative analysis of the impact of environmentally relevant concentrations of LDPE, HDPE, and PVC microplastic contamination (2 %, 4 %, and 6 %) on index properties and strength parameters of sandy, silty and clayey soil types at varying observation days 5,10,15,20,25, and 30 days. Extensive experimental investigations are carried out to understand the effect of contamination on moisture content, specific gravity, liquid limit, plastic limit, plasticity index, optimum moisture content, maximum dry density, and shear strength parameters of the respective soil type. It is observed that the depletion in Atterberg's limits is found more in the case of clayey soil as compared to silty soil because clayey soils consist of large specific surface areas leading to van der Waals force of attraction being the predominant force between particles, compared with silty soil which is affected by microplastic addition leading to decrease in net attractive forces. In the case of clayey soil maximum depletion of liquid limit up to 168 %, plastic limit up to 33 %, plasticity index (136 %), and optimum moisture content (9.04 %) is observed for PVC microplastic. The deduction in maximum dry density values is observed more for sandy soil (0.59 g/cc) followed by silty soil (0.21 g/cc) and clayey soil (0.12 g/cc). The maximum depletion of moisture content(delta-8 %), shear strength (delta-0.89 kg/cm2), and maximum dry density (delta-0.44 g/cc) is observed in the case of sandy soil for PVC and LDPE microplastic contamination. Significant depletion in optimum moisture content is observed in the case of clayey soil (9.57 %) compared to sandy (5.62 %) and silty soil (5.3 %). An increase in cohesion is observed for sandy soil (0.09 kg/cm2) and a decrease for clayey (0.19 kg/cm2) and silty soil (0.19 kg/cm2). The angle of internal friction is reduced in the case of clayey soil (∆-14.380) followed by silty soil (∆-11.230) and sandy soil (∆-11.020). For silty soil maximum depletion of specific gravity(delta-1.06) and cohesion (0.192 kg/cm2) is observed for LDPE and HDPE microplastic. The sandy soil type is most affected due to microplastic contamination irrespective of the type of microplastic contamination followed by clayey soil and the silty soil type is least affected. The maximum overall shear strength is reduced due to microplastic contamination in all the soil types.

Effects of microplastic interaction with persistent organic pollutants on the activity of the aryl hydrocarbon and estrogen receptors

Environmental microplastics (MPs) are complex mixtures of plastic polymers and sorbed chemical pollutants with high degrees of heterogeneity, particularly in terms of particle size, morphology and degree of weathering. Currently, limitations exist in sampling sufficient amounts of environmental particles for laboratory studies to assess toxicity endpoints with statistical rigor and to examine chemical pollutant interactions. This study seeks to bridge this gap by investigating environmental plastic particle mimetics and pollutant-polymer interactions by mixing polymer particles with persistent organic pollutants (POPs) at set concentrations over time. Solutions containing combinations of polymers including polystyrene (PS), polypropylene (PP), polyethylene terephthalate (PET), and polyamide (PA) and POPs including 2,3,7,8 -Tetrachlorodibenzo-p-dioxin (TCDD), bisphenol A (BPA), and atrazine, were stirred for up to 19 weeks and monitored using assays to test for aryl hydrocarbon (AhR) and estrogen receptor (ER) activity which are cell signaling pathways impacted by environmental pollutants. TCDD induced AhR activity decreased over time in the presence of PS in a surface area dependent manner. BPA and atrazine also exhibited AhR antagonist activity in the presence of TCDD. The addition of BPA slowed the loss of activity but atrazine did not, suggesting that polymer chemistry impacts interactions with POPs. We also observed potential differences in TCDD sorption with different plastic polymers and that higher concentrations of PS particles may inhibit BPA-induced estrogen receptor activation. These results emphasize the need for additional understanding of how POPs and polymer chemistry impact their interaction and toxicity.

Evidence that microplastics at environmentally relevant concentration and size interfere with energy metabolism of microalgal community

To address two current issues in evaluating the toxicity of microplastics (MPs) namely, conflicting results due to species specificity and the ecological irrelevance of laboratory data, this study conducted a 10-day exposure experiment using a microalgal community comprising three symbiotic species. The experiment involved virgin and Benzo[a]pyrene-spiked micron-scale fibers and fragments made of polyethylene terephthalate (PET) and polypropylene (PP). The results showed that, from a physiological perspective, environmentally relevant concentrations of micron-scale MPs decreased saccharide accumulation in microalgal cells, as confirmed by ultrastructural observations. MPs may increase cellular energy consumption by obstructing cellular motility, interfering with nutrient uptake, and causing sustained oxidative stress. Additionally, MPs and adsorbed B[a]P induced DNA damage in microalgae, potentially further disrupting cellular energy metabolism. Ecologically, MPs altered the species abundance in microalgal communities, suggesting they could weaken the ecological functions of these communities as producers and affect ecosystem diversity and stability. This study marks a significant advancement from traditional single-species toxicity experiments to community-level assessments, providing essential insights for ecological risk assessment of microplastics and guiding future mechanistic studies utilizing multi-omics analysis.

Stressful Effects of Individual and Combined Exposure to Low-Concentration Polylactic Acid Microplastics and Chromium on Marine Medaka Larvae (Oryzias melastigma)

Microplastics and heavy metal pollution frequently co-occur in the marine environment, raising concerns about their potentially harmful impacts on marine fish. This study undertook a comprehensive evaluation of the individual and combined stress effects of polylactide microplastics (PLA-MPs) and chromium (Cr) on marine medaka larvae. Following a 14-day exposure to PLA-MPs (100 μg/L) and Cr (50 μg/L), both individually and in combination, significant increases in heart rate and body length were observed. Notably, the combined exposure to PLA-MPs and Cr caused marked histopathological alterations, including shedding, atrophy, and lysis of the intestinal tissues. Furthermore, both individual and combined exposure induced oxidative stress in fish larvae, leading to changes in various enzyme activity indices. Individual exposure to either PLA-MPs or Cr led to anxious behavior in the larvae, whereas combined exposure not only caused anxious behavior but also altered swimming patterns. These findings suggest that combined exposure to PLA-MPs and Cr can exacerbate the toxic effects on marine medaka larvae.

Exploring adsorption dynamics of heavy metals onto varied commercial microplastic substrates: Isothermal models and kinetics analysis

The increasing presence of plastics in the environment has raised concerns about their potential impact, especially as carriers of heavy metals such as Cd, Ni, and Pb. However, the adsorption mechanism of heavy metals on microplastics remains poorly understood. In this study, we investigated the adsorption behavior of Cd, Ni, and Pb by polystyrene (PS) and polypropylene (PP) microplastics to better comprehend their interaction and potential environmental implications. Our results revealed that equilibrium adsorption of microplastics with different heavy metals was achieved within a 6-h contact time. The FTIR analysis findings, which suggest that physical interactions play a significant role in the adsorption of heavy metals onto microplastics, are further supported by the observed changes in surface morphology after adsorption. We explored the influence of solution pH, contact duration, and initial concentration on the adsorption capacity and found significant effects on the adsorption behavior. To model the adsorption process, we applied Langmuir and Freundlich adsorption isotherm models and observed that the Langmuir model better fit the experimental data. Furthermore, we compared the pseudo-first and pseudo-second-order kinetic models and found that the pseudo-second-order model provided a more accurate description of the adsorption kinetics. Notably, the adsorption percentages varied depending on the type of microplastic and experimental conditions. Overall, this study enhances our understanding of the adsorption mechanism of heavy metals on microplastics and provides valuable insights into their behavior in aquatic environments. These findings have implications for the development of effective strategies for mitigating pollution caused by microplastics and heavy metals in aquatic ecosystems.

Exposure Pathways and Toxicity of Microplastics in Terrestrial Insects

The detrimental effects of plastics on aquatic organisms, including those of macroplastics, microplastics, and nanoplastics, have been well established. However, knowledge on the interaction between plastics and terrestrial insects is limited. To develop effective strategies for mitigating the impact of plastic pollution on terrestrial ecosystems, it is necessary to understand the toxicity effects and influencing factors of plastic ingestion by insects. An overview of current knowledge regarding plastic ingestion by terrestrial insects is provided in this Review, and the factors influencing this interaction are identified. The pathways through which insects interact with plastics, which can lead to plastic accumulation and microplastic transfer to higher trophic levels, are also discussed using an overview and a conceptual model. The diverse impacts of plastic exposure on insects are discussed, and the challenges in existing studies, such as a limited focus on certain plastic types, are identified. Further research on standardized methods for sampling and analysis is crucial for reliable research, and long-term monitoring is essential to assess plastic trends and ecological impacts in terrestrial ecosystems. The mechanisms underlying these effects need to be uncovered, and their potential long-term consequences for insect populations and ecosystems require evaluation.

Toxicological review of micro- and nano-plastics in aquatic environments: Risks to ecosystems, food web dynamics and human health

The increase of micro- and nano-plastics (MNPs) in aquatic environments has become a significant concern due to their potential toxicological effects on ecosystems, food web dynamics, and human health. These plastic particles emerge from a range of sources, such as the breakdown of larger plastic waste, consumer products, and industrial outputs. This review provides a detailed report of the transmission and dangers of MNPs in aquatic ecosystems, environmental behavior, and interactions within aquatic food webs, emphasizing their toxic impact on marine life. It explores the relationship between particle size and toxicity, their distribution in different tissues, and the process of trophic transfer through the food web. MNPs, once consumed, can be found in various organs, including the digestive system, gills, and liver. Their consumption by lower trophic level organisms facilitates their progression up the food chain, potentially leading to bioaccumulation and biomagnification, thereby posing substantial risks to the health, reproduction, and behavior of aquatic species. This work also explores how MNPs, through their persistence and bioaccumulation, pose risks to aquatic biodiversity and disrupt trophic relationships. The review also addresses the implications of MNPs for human health, particularly through the consumption of contaminated seafood, highlighting the direct and indirect pathways through which humans are exposed to these pollutants. Furthermore, the review highlights the recommendations for future research directions, emphasizing the integration of ecological, toxicological, and human health studies to inform risk assessments and develop mitigation strategies to address the global challenge of plastic pollution in aquatic environments.

Comments to "Degli-Innocenti, F. The pathology of hype, hyperbole and publication bias is creating an unwarranted concern towards biodegradable mulch films" [J. Hazard. Mater. 463 (2024) 132923]

Some narratives present biodegradable plastic use for soil mulching practices in agriculture as "environmentally friendly" and "sustainable" alternatives to conventional plastics. To verify these narratives, environmental research recently started focusing on their potential impact on soil health, highlighting some concerns. The paper by Degli-Innocenti criticizes this unfolding knowledge arguing that it is affected by communication hypes, alarmistic writing and a focus on exposure scenarios purposedly crafted to yield negative effects. The quest of scientists for increased impact - the paper concludes - is the driver of such behavior. As scholars devoted to the safeguarding of scientific integrity, we set to verify whether this serious claim is grounded in evidence. Through a bibliometric analysis (using number of paper reads, citations and mentions on social media to measure the impact of publications) we found that: i) the papers pointed out by Degli-Innocenti as examples of biased works do not score higher than the median of similar publications; ii) the methodology used to support the conclusion is non-scientific; and iii) the paper does not fulfil the requirements concerning disclosure of conflicts of interests. We conclude that this paper represents a non-scientific opinion, potentially biased by a conflict of interest. We ask the paper to be clearly tagged as such, after the necessary corrections on the ethic section have been made. That being said, the paper does offer some useful insights for the definition of exposure scenarios in risk assessment. We comment and elaborate on these proposed models, hoping that this can help to advance the field.

Exchangeable versus residual metals in naturally aged plastic litter

Metals may be associated with plastics as additives arising from manufacture or through acquisition from the environment, but these associations are often poorly defined or referred to synonymously when considering metal availability. In this study, samples of plastic litter (n = 22) have been collected from various environmental and industrial compartments of Lublin Province, Poland, and fractionated according to polymer type (polyethylene, polyethylene terephthalate, nylon, expanded polystyrene, polypropylene, and "mixed") before being micronised to < 2 mm. Composites (n = 89) were subjected to two phases of a standardised and widely employed sequential extraction protocol (Bureau Communautaire de Reference; BCR) in order to define available (acid-soluble and exchangeable) and residual (soluble in boiling aqua regia) concentrations of Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn. For a given metal, total content, calculated by summing available and residual components, was highly variable, both between locations and amongst polymer categories, reflecting the heterogeneous distribution of a multitude of different additives. Overall, however, concentrations were greatest for Fe, with medians of several hundred to several thousand mg kg-1 amongst the different polymers, and lowest for Cd, Co, and Ni, where nearly all concentrations were below 10 mg kg-1. Median percentage metal availabilities were greatest for expanded polystyrene and were above 25% for Mn and Zn and below 10% for Cr and Fe in all polymer types. These observations are largely, but not entirely, attributed to the relative contributions of metals acquired from the environment and metals present as additives and residues. Significantly, the approach employed allows direct comparisons of metal availability in plastics with metal availability in environmental solids in order to evaluate the overall impacts of plastics in metal risk assessments.

Abiotic weathering of plastic: Experimental contributions towards understanding the formation of microplastics and other plastic related particulate pollutants

The increasing use of plastic (synthetic polymers) results in the release of uncontrollable amounts of synthetic materials into the environment through waste, infrastructure, and essential goods. As plastic materials undergo weathering, a complex process unfolds, leading to the formation of pollutants, notably microplastics. This study employs multiple instrumental methods to explore the intricate abiotic degradation of the five most commonly used synthetic polymers in environmentally relevant conditions. An extensive set of analytical techniques, along with chemometric analysis of the results of Raman spectroscopy, was used to characterize the materials and evaluate the nature and extent of degradation caused by artificial weathering under temperature, humidity, and solar-like irradiation cycles. Investigation focuses on the link between abiotic weathering and the generation of micro- and nanoplastics, accompanied by molecular and surface adhesion changes, and the release of additives such as metals and metal oxides. Research reveals that microplastics may exhibit varied physical properties due to the incorporation of significant quantities of high-density additives from the parent plastic, which might influence the extraction methods and the transportation models' accuracy. At the molecular and microscopic scales, non-homogeneous pathways through which plastic decomposes during weathering were observed. The formation of additive-polymer combinations might play a pivotal role in the monitoring approaches for microplastics, presenting unique challenges in assessing the environmental impact of different plastic types. These findings offer complex insight into abiotic weathering, microplastics' generation, and the influence of additives that were previously overlooked in toxicity and health assessment studies. As plastic pollution continues to escalate, understanding these complex processes is crucial for microplastic monitoring development and adopting effective preventative measures.

Microplastics as vectors of other contaminants: Analytical determination techniques and remediation methods

The ubiquitous and persistent presence of microplastics (MPs) in aquatic and terrestrial ecosystems has raised global concerns due to their detrimental effects on human health and the natural environment. These minuscule plastic fragments not only threaten biodiversity but also serve as vectors for contaminants, absorbing organic and inorganic pollutants, thereby causing a range of health and environmental issues. This review provides an overview of microplastics and their effects. This work highlights available analytical techniques for detecting and characterizing microplastics in different environmental matrices, assessing their advantages and limitations. Additionally, this review explores innovative remediation approaches, such as microbial degradation and other advanced methods, offering promising prospects for combatting microplastic accumulation in contaminated environments. The focus on environmentally-friendly technologies, such as the use of microorganisms and enzymes for microplastic degradation, underscores the importance of sustainable solutions in plastic pollution management. In conclusion, this article not only deepens our understanding of the microplastic issue and its impact but also advocates for the urgent need to develop and implement effective strategies to mitigate this critical environmental challenge. In this context, the crucial role of advanced technologies, like quantitative Nuclear Magnetic Resonance spectroscopy (qNMR), as promising tools for rapid and efficient microplastic detection, is emphasized. Furthermore, the potential of the enzyme PETase (polyethylene terephthalate esterase) in microplastic degradation is examined, aiming to address the growing plastic pollution, particularly in saline environments like oceanic ecosystems. These innovations offer hope for effectively addressing microplastic accumulation in contaminated environments and minimizing its adverse impacts.

Soil protists are more resilient to the combined effect of microplastics and heavy metals than bacterial communities

Heavy metals and micro-/nanoplastic pollution seriously threaten the environment and ecosystems. While many studies investigated their effects on diverse microbes, few studies have focused on soil protists, and it is unclear how soil protists respond to the combined effect of micro-/nanoplastics and heavy metals. This study investigated how soil protistan and bacterial communities respond to single or combined copper and micro-/nanoplastics. The bacterial community exhibited an instantaneous response to single copper pollution, whereas the combined pollution resulted in a hysteresis effect on the protistan community. Single and combined pollution inhibited the predation of protists and changed the construction of ecological networks. Though single and combined pollution did not significantly affect the overall community structure, the exposure experiment indicated that combined pollution harmed soil amoeba's fitness. These findings offer valuable new insights into the toxic effects of single and combined pollution of copper and plastics on soil protistan and bacterial communities. Additionally, this study shows that sequencing-based analyses cannot fully reflect pollutants' adverse effects, and both culture-independent and dependent methods are needed to reveal the impact of pollutants on soil microbes.

Microplastics and potentially toxic elements: A review of interactions, fate and bioavailability in the environment

In recent years, microplastics (MPs) have obtained growing public concern due to widespread distribution and harmful impacts. Their distinctive features including porous structure, small size, as well as large specific surface area render MPs to be carriers for transporting other pollutants in the environment, especially potentially toxic elements (PTEs). Considering the hot topic of MPs, it is of great significance to comb the reported literature on environmental behaviors of co-occurrence of MPs and PTEs, and systematically discuss their co-mobility, transportation and biotoxicity to different living organisms in diverse environmental media. Therefore, the aim of this work is to systematically review and summarize recent advances on interactions and co-toxicity of MPs and PTEs, in order to provide in-depth understanding on the transport behaviors as well as environmental impacts. Electrostatic attraction and surface complexation mainly govern the interactions between MPs and PTEs, which are subordinated by other physical sorption processes. Besides, the adsorption behaviors are mainly determined by physicochemical properties regarding to different MPs types and various condition factors (e.g., ageing and PTEs concentrations, presence of substances). Generally speaking, recently published papers make a great progress in elucidating the mechanisms, impact factors, as well as thermodynamic and kinetic studies. Bioavailability and bioaccumulation by plant, microbes, and other organisms in both aquatic and terrestrial environment have also been under investigation. This review will shed novel perspectives on future research to meet the sustainable development goals, and obtain critical insights on revealing comprehensive mechanisms. It is crucial to promote efficient approaches on environmental quality improvement as well as management strategies towards the challenge of MPs-PTEs.

Combined effects of bacteria and antibiotics on surface properties and transport of nanoplastics in porous media

Currently, research on the individual effects of bacteria and antibiotics on the transport of nanoplastics (NPs) in porous media is in its infancy, while research on their combined effect is absent. It is well known that bacteria and antibiotics also interact with each other, so this synergistic transport of bacteria, antibiotics, and NPs in porous media must be very interesting. For exploring this aspect, we investigated the individual and combined effects of bacteria and antibiotics on the transport of polystyrene NPs (PS-NPs) in saturated porous media. Hydrophobicity, roughness, and the Derjaguin-Landau-Verwey-Overbeek (DLVO) interaction energy were measured and calculated. The PS-NPs' transport in porous media was fitted using a mathematical model. Enhanced roughness and size of PS-NPs with increased bacterial concentration dominated and inhibited the PS-NPs' transport in porous media, although the hydrophilicity of PS-NPs and the energy barrier between PS-NPs and porous media were also increased. An increase in antibiotic concentration reduced the energy barrier between PS-NPs and porous media, thereby decreasing the PS-NPs' transport. Combined effects of bacteria and antibiotics on the PS-NPs' transport were complex and distinct from individual effects, but the mechanisms were clear. Roughness and hydrophilicity of PS-NPs and the DLVO interaction energy between PS-NPs and porous media together influenced this process. In the presence of bacteria, antibiotics could alter the bacterial surface roughness by altering bacterial extracellular polymeric substances, and thus alter the PS-NPs' surface roughness, thereby affecting the PS-NPs' transport in porous media. When antibiotics were present, enhanced bacterial concentration increased the PS-NPs' hydrophilicity and the energy barrier between PS-NPs and porous media, thus promoting the PS-NPs' transport. The findings of this study provided a theoretical basis for clarifying the transport of NPs in porous media under complex environments, facilitating a reduction in environmental pollution of NPs.

Co-exposure of microplastics and heavy metals in the marine environment and remediation techniques: a comprehensive review

Microplastics (MPs) and heavy metals are significant pollutants in the marine environment, necessitating effective remediation strategies to prevent their release into the sea through sewage and industrial effluent. This comprehensive review explores the current understanding of the co-exposure of MPs and heavy metal-enriched MPs, highlighting the need for effective remediation methods. Various mechanisms, including surface ion complexation, hydrogen bonding, and electrostatic forces, contribute to the adsorption of heavy metals onto MPs, with factors like surface area and environmental exposure duration playing crucial roles. Additionally, biofilm formation on MPs alters their chemical properties, influencing metal adsorption behaviors. Different thermodynamic models are used to explain the adsorption mechanisms of heavy metals on MPs. The adsorption process is influenced by various factors, including the morphological characteristics of MPs, their adsorption capacity, and environmental conditions. Additionally, the desorption of heavy metals from MPs has implications for their bioavailability and poses risks to marine organisms, emphasizing the importance of source reduction and remedial measures. Hybrid approaches that combine both conventional and modern technologies show promise for the efficient removal of MPs and heavy metals from marine environments. This review identifies critical gaps in existing research that should be addressed in future studies including standardized sampling methods to ensure accurate data, further investigation into the specific interactions between MPs and metals, and the development of hybrid technologies at an industrial scale. Overall, this review sheds light on the adsorption and desorption mechanisms of heavy metal-enriched MPs, underscoring the necessity of implementing effective remediation strategies.

Mitigating persistent organic pollutants from marine plastics through enhanced recycling: A review

The escalating crisis of marine plastic waste pose threats to the marine ecosystems. Statistics revealed that a staggering 8 MMT of plastic inundates the marine atmosphere annually. This review delves into a pivotal aspect of this issue, examining the release of additives like brominated flame retardants, phthalates, and bisphenol A from plastic into the environment. It also underscores the concealed chemical hazards plastic introduces to the marine ecosystem's air, water, and sediment. As plastic degrades and breaks down, it generates microplastics and nanoplastics, exacerbating the widespread detrimental effects on marine life and even affecting terrestrial ecosystems, imperiling the overall health and stability of various organisms. While mechanical recycling, chemical recycling, and dissolution-reprecipitation demonstrated potential in addressing marine plastic debris, further research and development are needed to surmount associated challenges to increase the efficiency of current recycling method. This comprehensive review elaborates on the current fate and consequences associated with plastic pollution in marine environments. It emphasizes the urgent need for initiatives to confront this imminent ecological crisis, accentuating the necessity of protecting the marine environment and their delicate ecosystems from the pervasive threat of plastic waste.

Microplastics and trace metals in river sediment: Prevalence and correlation with multiple factors

Microplastics (MPs), which are ubiquitous, are no longer novel emerging pollutants, yet our knowledge of them is insufficient. This study investigates the prevalence of MPs and trace metals in sediment belonging to Ma River, Vietnam, and their interaction with various parameters, including nutrients such as total carbon (TC), total nitrogen (TN), and total phosphorus (TP), grain sizes, and MPs in surface water. The study revealed that the abundance of MPs in sediment (MPs/S) is relatively high (i.e., 1328.3 ± 1925.5 items.kg-1 dry weight), while the concentration of MPs in surface water (MPs/W) was relatively low (i.e., 57.3 ± 55.8 items.m-3) compared to other areas. Notably, the study found that arsenic and cadmium concentrations exceeded baseline levels, indicating their anthropogenic origin. To interpret the relationship between MPs/S, metals, and the aforementioned parameters, principal component analysis and Pearson correlation analyses were employed. The results demonstrated a significant correlation between metals and nutrients, as well as small grain sizes such as clay and silt. It was observed that the majority of metals displayed co-occurrence with one another but showed weak associations with the levels of MPs present in both water and sediment. Additionally, a weak correlation was observed between MPs/W and MPs/S. In conclusion, these findings suggest that the distribution and behavior of MPs and trace metals in aquatic systems are influenced by multiple factors, including nutrient levels, grain size, and other chemical and physical characteristics of the environment. While certain metals may have natural sources, others may result from human activities such as mining, industrial discharge, and wastewater treatment plants. As a result, understanding the sources and aspects of metal contamination are critical for determining their relationship with MPs and developing effective strategies for mitigating their impact on aquatic ecosystems.

Microplastics exhibit lower carrying effects on the bioaccessibility and cytotoxicity of lead than montmorillonite clay particles

Microplastics (MPs) in the environment are always colonized by microbes, which may have implications for carrying effect of pollutants and exposure risk in organisms. We present the crucial impacts and mechanisms of microbial colonization on the bioaccessibility and toxicity of Pb(II) loaded in disposable box-derived polypropylene (PP) and polystyrene (PS) MPs and montmorillonite (MMT) clay particles. After 45 d incubation, higher biomass measured by crystal violet staining were detected in MMT (1.23) than in PP and PS (0.400 and 0.721) indicating preferential colonization of microbes in clay particles. Microbial colonization further enhanced the sorption ability toward Pb(II), but inhibited the desorption and bioaccessibility of enriched Pb(II) in zebrafish and decreased the toxicity to gastric epithelial cells in an order of MMT > PS ≈ PP. The crucial effects were mainly because microbe-colonized substrates possessed higher oxygen functional groups and specific surface area and exhibited stronger interactions with Pb(II) and digestive component (i.e., pepsin) than pure substrates. This decreased the available soluble pepsin for complexing with sorbed Pb(II). The findings highlight the role of microbial colonization in modulating the exposure risks of artificial and natural substrate-associated pollutants and suggest that the risks of MPs may be overestimated compared to clay particles.

Microplastics are overestimated due to poor quality control of reagents

Microplastics are widely distributed in the environment and pose potential ecological risks, increasing to be one of the most important environmental pollutants. However, when assessing the characteristics of microplastic contamination in environmental samples, inadequate quality control measures for the working solutions may introduce additional microplastic contamination and lead to an overestimation of microplastic abundance in the samples. In this study, we evaluated the microplastic contamination characteristics in commonly used flotation and digestion reagents to assess errors caused by microplastics in the reagents. The results showed that the abundance of microplastics in the reagents ranged from 0.8 to 43.4 items/g, with the abundance of microplastics in flotation reagents being lower than that in digestion reagents. The shapes of the detected microplastics included particles, fibers, and fragments, and their size and outline were generally small, with most being below 100 µm. The most common types of polymers detected were polyethylene and polypropylene. In order to improve the universality and readability of the results, the detected microplastic abundances were converted into the actual application concentration of the working fluid. It was found that the potential contamination of microplastics in untreated flotation solutions ranged from 1.5 to 30.8 items/mL, while in digestion solutions ranged from 0.1 to 2.3 items/mL. Our study emphasizes the need for quality control measures, such as suction filtration, when evaluating microplastics in environmental samples or conducting chemical and biological tests related to microplastics.

Global hotspots and trends in interactions of microplastics and heavy metals: a bibliometric analysis and literature review

Microplastics (MPs) are identified as emerging contaminants; however, their interactions with heavy metals in the environment have not been well elucidated. Here, the research progress, hotspots, and trends in the interactions of MPs and heavy metals were analyzed at a global scale using a bibliometric analysis combined with a literature review. We comprehensively searched the Web of Science Core Collection database from 2008 to July 5, 2022. A total of 552 articles published in 124 journals were selected, which came from 70 countries and 841 institutions. The most contributing journals, countries, institutions, and authors were identified. Visualization methods were used to identify high co-citation references and hot keywords in the 552 articles. Evolutionary and cluster analyses of hot keywords suggested several research hotspots in the co-contamination of MPs and heavy metals, including their toxicity and bioaccumulation, the adsorption and desorption behaviors, the environmental pollution and risk assessment, and their detection and characterization. Based on the current research status, several directions of priority are recommended to understand the interactions between MPs and heavy metals and their potential risks. This article can help recognize the current research status and future directions in this field.

Anthropogenic and natural contribution of potentially toxic elements in southwestern Ganges-Brahmaputra-Meghna delta, Bangladesh

Elemental composition, multivariate statistical analyses with the absolute principal component score-multiple linear regression (APCS-MLR) model, and different pollution indices in Upper and Lower Southwestern Ganges-Brahmaputra-Meghna (GBM) delta sediments were studied to characterize pollution, ecological risk and quantify potential toxic element sources of the area. Toxic metals concentrations were higher in Lower Delta and individual pollution indices showed Upper Delta was moderately polluted by arsenic, chromium, cobalt, copper and lead, and Lower Delta was moderately-strongly polluted by the same metals. Synergistic indices include Potential Ecological, Toxic, Nemerow, and Pollution Risk indices in Upper and Lower Delta sediment ranged from 47.17-128.07, 2.03-12.19, 29.92-65.42, 0.28-1.62, and 69.17-246.90, 8.00-13.47, 20.53-152.92, 1.18-1.58, indicated low and moderate risk pollution, respectively. Statistical models represent the metals dominantly originated from nature for Upper Delta, and both natural and anthropogenic activities contributed to Lower Delta sediment. The study found that the modern deposit in Lower Delta became more contaminated and thus enhanced ecological risk.

Consumption of commercially sold dried fish snack "Charales" contaminated with microplastics in Mexico

Inadvertent human exposure to microplastics by the ingestion of microplastic-contaminated processed foods poses health risks and new preventative issues; nevertheless, investigations analyzing microplastic occurrences in commercially dried fish for direct human consumption are scarce. This study assessed the abundance and characteristics of microplastics in 25 commercially sold dried fish products (4 supermarkets, 3 street vendors, and 18 traditional agri-product farmers' markets) from two widely consumed and commercially important Chirostoma species (C. jordani and C. patzcuaro) in Mexico. Microplastics were detected in all the samples examined, with abundances ranging from 4.00 ± 0.94 to 55.33 ± 9.43 items g^-1. C. jordani dried fish samples had higher mean microplastic abundance (15.17 ± 5.90 items g^-1) than the C. patzcuaro dried fish samples (7.82 ± 2.90 items g^-1); nevertheless, there was no statistically significant difference in microplastic concentrations between the samples. The most prevalent type of microplastic was fiber (67.55%), followed by fragment (29.18%), film (3.00%), and sphere (0.27%). Non-colored microplastics (67.35%) predominated, while microplastic sizes varied from 24 to 1670 μm, with sizes less than 500 μm (84%) being the most common. ATR-FTIR analysis revealed polyester, acrylonitrile butadiene styrene, polyvinyl alcohol, ethylene-propylene copolymer, nylon-6 (3), cellophane, and viscose in the dried fish samples. Overall, this study's findings are the first in Latin America to demonstrate microplastic contamination in dried fish for human consumption, underscoring the need for developing countermeasures to prevent plastic pollution in fish-caught regions and reduce the risks of human exposure to these micropollutants.

Sorbed environmental contaminants increase the harmful effects of microplastics in adult zebrafish, Danio rerio

Aquatic animals ingest Microplastics (MPs) which have the potential to affect the uptake and bioavailability of sorbed co-contaminants. However, the effects on living organisms still need to be properly understood. The present study was designed to assess the combined effects of MPs and environmental contaminants on zebrafish (Danio rerio) health and behavior. Adult specimens were fed according to three different protocols: 1) untreated food (Control group); 2) food supplemented with 0.4 mg/L pristine polyethylene-MPs (PE-MPs; 0.1-0.3 mm diameter) (PEv group); 3) food supplemented with 0.4 mg/L PE-MPs previously incubated (PEi group) for 2 months in seawater. Analysis of contaminants in PEi detected trace elements, such as lead and copper. After 15 days of exposure, zebrafish underwent behavioral analysis and were then dissected to sample gills and intestine for histology, and the latter also for microbiome analysis. Occurrence of PEv and PEi in the intestine and contaminants in the fish carcass were analyzed. Both PEv- and PEi-administered fish differed from controls in the assays performed, but PEi produced more harmful effects in most instances. Overall, MPs after environmental exposure revealed higher potential to alter fish health through combined effects (e.g. proportion of microplastics, pollutants and/or microorganisms).

Factors Affecting the Adsorption of Heavy Metals by Microplastics and Their Toxic Effects on Fish

Fish not only constitute an important trophic level in aquatic ecosystems but also serve as an important source of protein for human beings. The health of fish is related to the sustained and healthy development of their entire aquatic ecosystem. Due to the widespread use, mass production, high disposal frequency, and degradation resistance of plastics, these pollutants are released into aquatic environments on a large scale. They have become one of the fastest growing pollutants and have a substantial toxic effect on fish. Microplastics have intrinsic toxicity and can absorb heavy metals discharged into water. The adsorption of heavy metals onto microplastics in aquatic environments is affected by many factors and serves as a convenient way for heavy metals to migrate from the environment to organisms. Fish are exposed to both microplastics and heavy metals. In this paper, the toxic effects of heavy metal adsorption by microplastics on fish are reviewed, and the focus is on the toxic effects at the individual (survival, feeding activity and swimming, energy reserves and respiration, intestinal microorganisms, development and growth, and reproduction), cellular (cytotoxicity, oxidative damage, inflammatory response, neurotoxicity, and metabolism) and molecular (gene expression) levels. This facilitates an assessment of the pollutants' impact on ecotoxicity and contributes to the regulation of these pollutants in the environment.

Response mechanism and rapid detection of phenotypic information in rice root under heavy metal stress

The root is an important organ affecting cadmium accumulation in grains, but there is no comprehensive research involving rice root phenotype under cadmium stress yet. To assess the effect of cadmium on root phenotypes, this paper investigated the response mechanism of phenotypic information including cadmium accumulation, adversity physiology, morphological parameters, and microstructure characteristics, and explored rapid detection methods of cadmium accumulation and adversity physiology. We found that cadmium had the effect of "low-promotion and high-inhibition" on root phenotypes. In addition, the rapid detection of cadmium (Cd), soluble protein (SP), and malondialdehyde (MDA) were achieved based on spectroscopic technology and chemometrics, where the optimal prediction model was least squares support vector machine (LS-SVM) based on the full spectrum (R_p=0.9958) for Cd, competitive adaptive reweighted sampling-extreme learning machine (CARS-ELM) (R_p=0.9161) for SP and CARS-ELM (R_p=0.9021) for MDA, all with R_p higher than 0.9. Surprisingly, it took only about 3 min, which was more than 90% reduction in detection time compared with laboratory analysis, demonstrating the excellent ability of spectroscopy for root phenotype detection. These results reveal response mechanism to heavy metal and provide rapid detection method for phenotypic information, which can substantially contribute to crop heavy metal control and food safety supervision.

Recovery of Li and Co in Waste Lithium Cobalt Oxide-Based Battery Using H1.6Mn1.6O4

H_1.6Mn_1.6O₄ lithium-ion screen adsorbents were synthesized by soft chemical synthesis and solid phase calcination and then applied to the recovery of metal Li and Co from waste cathode materials of a lithium cobalt oxide-based battery. The leaching experiments of cobalt and lithium from cathode materials by a citrate hydrogen peroxide system and tartaric acid system were investigated. The experimental results showed that under the citrate hydrogen peroxide system, when the temperature was 90 °C, the rotation speed was 600 r·min^-1 and the solid-liquid ratio was 10 g·1 L^-1, the leaching rate of Co and Li could reach 86.21% and 96.9%, respectively. Under the tartaric acid system, the leaching rates of Co and Li were 90.34% and 92.47%, respectively, under the previous operating conditions. The adsorption results of the lithium-ion screen showed that the adsorbents were highly selective for Li⁺, and the maximum adsorption capacities were 38.05 mg·g^-1. In the process of lithium removal, the dissolution rate of lithium was about 91%, and the results of multiple cycles showed that the stability of the adsorbent was high. The recovery results showed that the purity of LiCl, Li₂CO₃ and CoCl₂ crystals could reach 93%, 99.59% and 87.9%, respectively. LiCoO₂ was regenerated by the sol-gel method. XRD results showed that the regenerated LiCoO₂ had the advantages of higher crystallinity and less impurity.

The spatial distribution and abundance of microplastics in lake waters and ice during ice-free and ice-covered periods

Understanding the spatial distribution and characteristics of microplastics (MPs) in lake waters is essential to assessing and addressing lacustrine MP pollution. This study investigated how lake ice affects the abundance, spatial distribution, and characteristics (size, shape) of MPs in Lake Ulansuhai by analyzing samples collected at ten sites uniformly distributed throughout the lake during ice-free and ice-covered periods. The abundance of MPs ranged between 204 ± 28 and 1224 ± 185 n·L^-1 in lake waters during the ice-free period, and from 34 ± 8 to 216 ± 21 n·L^-1 and 269 ± 84 to 915 ± 117 n·L^-1 in water and ice during the ice-covered period, respectively. During the ice-covered period, MPs were 2.74-8.14 times higher in the ice than in water beneath the ice. Ice formation decreased MP abundance in lake waters, in part, by incorporating a relatively high percentage of MPs into the ice mass during freezing and by inhibiting atmospheric MPs from reaching the lake waters. The abundance of MPs in the water during the ice-free period was 4.50-11.30 times greater than during the ice-covered period. Seasonal variations in MP shape also occurred; the proportion of fibrous MPs in water decreased during the ice-covered period. Variations in MP abundance were partly due to differences in sedimentation rates; the settling of fibrous MPs is slower, making it easier for them to be captured during the formation of surface ice. Spatially, MPs were uniformly distributed during the ice-free period, but exhibited a spatially distinct pattern during ice-covered periods, when MPs in lake waters were higher in the northeast and lower in the southwest portions of the lake. During the ice-free period, small MPs (0.05-0.5 mm) were more likely to move with currents in the lake, whereas water velocities were reduced by ice formation, allowing small MPs to accumulate near the lake inlet.

A critical review on the interaction of polymer particles and co-existing contaminants: Adsorption mechanism, exposure factors, effects on plankton species

This review considers the interaction of microplastics (MPs)/nanoplastics (NPs) and co-existing contaminants, including organic contaminants, potentially toxic elements (PTEs), and metal/metal-oxide nanoparticles. Stronger adsorption between plastic particles and co-existing contaminants can either facilitate or prevent more contaminants to enter plankton. The characteristics of MPs/NPs, such as polymer type, size, functional groups, and weathering, affect combined effects. Mixture toxicity is affected by those factors simultaneously and also affected by the type of co-existing contaminants, their concentrations, exposure time, dissolved organic matter, and surfactant. For co-exposure involving organics and metal nanoparticles, marine Skeletonema costatum generally had antagonistic effects, while marine Chlorella pyrenoidosa, Platymonas subcordiformis, and Tetraselmis chuii, showed synergistic effects. For co-exposure involving organics and PTEs, both Chlorella sp. and Microcystis aeruginosa generally demonstrated antagonistic effects. Freshwater Chlorella reinhardtii and Scenedesmus obliquus had synergistic effects for co-exposure involving metal/metal oxide nanoparticles. Zooplankton shows more unpredicted sensitivity towards the complex system. Different co-existing contaminants have different metabolism pathways. Organic contaminants could be biodegraded, which may enhance or alleviate mixture toxicity. PTEs could be adsorbed and desorbed under changing environments, and further affect the combined effects. The presence of metal/metal-oxide nanoparticles is more complicated, since some may release ion metals, increasing contaminant composition.

Detection methods of micro and nanoplastics

Plastics and related contaminants (including microplastics; MPs and nanoplastics; NPs) have become a serious global safety issue due to their overuse in many products and applications and their inadequate management, leading to possible leakage into the environment and eventually to the food chain and humans. There is a growing literature reporting on the occurrence of plastics, (MPs and NPs) in both marine and terrestrial organisms, with many indications about the harmful impact of these contaminants on plants and animals, as well as potential human health risks. The presence of MPs and NPs in many foods and beverages including seafood (especially finfish, crustaceans, bivalves, and cephalopods), fruits, vegetables, milk, wine and beer, meat, and table salts, has become popular research areas in recent years. Detection, identification, and quantification of MPs and NPs have been widely investigated using a wide range of traditional methods, such as visual and optical methods, scanning electron microscopy, and gas chromatography-mass spectrometry, but these methods are burdened with a number of limitations. In contrast, spectroscopic techniques, especially Fourier-transform infrared spectroscopy and Raman spectroscopy, and other emerging techniques, such as hyperspectral imaging are increasingly being applied due to their potential to enable rapid, non-destructive, and high-throughput analysis. Despite huge research efforts, there is still an overarching need to develop reliable analytical techniques with low cost and high efficiency. Mitigation of plastic pollution requires establishing standard and harmonized methods, adopting holistic approaches, and raising awareness and engaging the public and policymakers. Therefore, this chapter focuses mainly on identification and quantification techniques of MPs and NPs in different food matrices (mostly seafood).

Effects of microplastics on arsenic uptake and distribution in rice seedlings

The potential of microplastics (MPs) and nanoplastics (NPs) to act as a carrier for heavy metals derived from the environment is of rising concern to the health of global ecosystems. Here, we investigated the effects of particle size of polystyrene micro/nano plastics on the uptake, accumulation, and toxicity of As in rice seedlings in a hydroponic system. Significant differences in As uptake and accumulation in different plant tissue were observed between the plants co-exposed to 82 nm NPs + As and 200 nm MPs + As. The NPs + As co-exposure led to higher As accumulation in rice leaves (12.4-36.7 %), while larger sized MPs + As(V) treatment reduced As accumulation in rice leaves. Furthermore, the co-exposure of NPs/MPs + As mitigated the rice growth inhibition caused by As toxicity. These results will provide insight into elucidating the potentially effects of nano/microplastics on As uptake and accumulation in crop plants for assessing the hazards of micro-and nanoplastics as pollutants in the food chain and environment.

Long-term deposition records of microplastics in a plateau lake under the influence of multiple natural and anthropogenic factors

Microplastic accumulation in the lake aquatic environment has attracted worldwide attention, but the long-term deposition characteristics and influencing factors of microplastics are not clear. Hence, we attempted to analyze the factors that influence the accumulation of microplastics during the process of natural environmental change and social development through the method of the sedimentological approach. In this investigation, the chronological sequence of sediment core was set up based on lead-210 composition to study microplastic accumulation rates in a plateau lake, Jianhu Lake. For the first time, the records of microplastic deposition were analyzed combined with multiple anthropogenic and natural factors, including 4 natural and 17 social factors to reveal the influence of natural processes and social development on microplastic abundances. The results showed that sediments were highly contaminated by microplastics, and the mean abundance of microplastics in the sediment cores of Jianhu Lake was 924 ± 427 particles/kg, and showed a gradually increasing trend from the bottom (25 to 30 cm) to surface layer (0 to 5 cm). Blue and black were the main colors of microplastics, and the average proportion of wirelike microplastics was 63 %. Additionally, the polymer type of microplastic was mainly rayon, the surface morphology of different polymer types was disparate, and various elements enriched on the surface of microplastics were also detected. In the past 70 years, the deposition rate of microplastics in Jianhu Lake maintained the trend of continuous growth, and the abundance of microplastics is projected to be 448 to 3017 and 513 to 3670 particles/kg by 2035 and 2050, respectively. What is more, there are significant correlations among multiple natural and anthropogenic factors and microplastic deposition, as well as microplastic polymer species.

Characteristics of microplastic pollution in golden pompano (Trachinotus ovatus) aquaculture areas and the relationship between colonized-microbiota on microplastics and intestinal microflora

Microplastic (MPs) pollution is a global marine environmental problem. The effects of MPs on the gut microbiota of aquatic organisms have received considerable attention. For example, microbes colonizing MPs in pond cultures alter the structure and function of the intestinal microbes of shrimp and fish. It was hypothesized that bacteria on MPs in natural mariculture areas also interact with the intestinal flora of golden pompano (Trachinotus ovatus) because biofilms can form on the surface of MPs during long-term floating in seawater. To our knowledge, this study is the first to investigate MPs pollution in T. ovatus aquaculture. DNA sequencing and bioinformatics analysis confirmed the effect of microbial colonization of MPs on the intestinal flora of T. ovatus. The MPs detected in the gut wet weight (w.w.) of golden pompano (546 ± 52 items/g) were mainly pellets and fragments of blue or green, whereas the sediment MPs dry weight (d.w.) (4765 ± 116 items/kg) were mainly black fibers. The MPs richness in the sediment gradually increased from the open-sea aquaculture area to the estuarine aquaculture area and was positively correlated with the MPs richness in the intestinal tract of golden pompano. MPs 20-200 μm were the most common in the gut and sediment. The intake of MPs increased the abundance of Proteobacteria and decreased that of Firmicutes in the intestinal flora. The functional compositions of MP-colonizing microbes and gut microbiota were similar, suggesting that the two communities influence each other. Network analysis further confirmed this and revealed that Vibrio plays a key role in the intestinal flora and surface microorganisms of MPs. Overall, the intake of MPs by aquatic animals not only affects the intestinal flora and intestinal microbial function, but also poses potential risks to aquaculture.

Effects of environmental and anthropogenic factors on the distribution and abundance of microplastics in freshwater ecosystems

Although microplastics are emerging marine pollutants that have recently attracted increasing attention, it is still difficult to identify their sources. This study reviewed 6487 articles to determine current research trends and found 237 effective concentration points after sorting, which were distributed in four regions and related to freshwater ecosystems. Results found that 15 environmental variables represented natural and anthropogenic environmental characteristics, of which seven environmental variables were selected for experimental modelling. Random forest models fitted sample data, thus facilitating the identification of regional microplastics distribution. The global random forest model had random forest importance scores (RFISs) for gross domestic product, population, and the proportion of agricultural land use were 15.76 %, 15.64 %, and 14.74 %, respectively; these indicate that human activities significantly affected the global distribution of microplastics. In Asia, agriculture and urban activities are the main sources of microplastics, with an RFIS of 11.58 % and 12.24 % for the proportion of agricultural and urban land use, respectively. Activities in urban areas were determined to be the main influencing factors in North America, with an RFIS of 13.92 % for the proportion of urban land use. Agricultural activities were the main influencing factors in Europe, with RFISs for the proportion of agricultural land use of 16.90 %. Our results indicate that region-specific policies are required to control microplastics in different regions, with soil composition being a latency factor that affects microplastics' distribution.

A critical review on the synthesis of NH2-MIL-53(Al) based materials for detection and removal of hazardous pollutants

Nowadays, emerging hazardous pollutants have caused many harmful effects on the environment and human health, calling for the state of the art methods for detection, qualification, and treatment. Metal-organic frameworks are porous, flexible, and versatile materials with unique structural properties, which can solve such problems. In this work, we reviewed the synthesis, activation, and characterization, and potential applications of NH₂-MIL-53(Al). This material exhibited intriguing breathing effects, and obtained very high surface areas (182.3-1934 m²/g) with diverse morphologies. More importantly, NH₂-MIL-53(Al) based materials could be used for the detection and removal of various toxic pollutants such as organic dyes, pharmaceuticals, herbicides, insecticides, phenols, heavy metals, and fluorides. We shed light on plausible adsorption mechanisms such as hydrogen bonds, π-π stacking interactions, and electrostatic interactions onto NH₂-MIL-53(Al) adsorbents. Interestingly, NH₂-MIL-53(Al) based adsorbents could be recycled for many cycles with high stability. This review also recommended that NH₂-MIL-53(Al) based materials can be a good platform for the environmental remediation fields.

Unraveling the potential human health risks from used disposable face mask-derived micro/nanoplastics during the COVID-19 pandemic scenario: A critical review

With the global spread of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), disposable face masks (DFMs) have caused negative environmental impacts. DFMs will release microplastics (MPs) and nanoplastics (NPs) during environmental degradation. However, few studies reveal the release process of MPs/NPs from masks in the natural environment. This review presents the current knowledge on the abiotic and biotic degradation of DFMs. Though MPs and NPs have raised serious concerns about their potentially detrimental effects on human health, little attention was paid to their impacts on human health from DFM-derived MPs and NPs. The potential toxicity of mask-derived MPs/NPs, such as gastrointestinal toxicity, pneumotoxicity, neurotoxicity, hepatotoxicity, reproductive and transgenerational toxicity, and the underlying mechanism will be discussed in the present study. MPs/NPs serve as carriers of toxic chemicals and pathogens, leading to their bioaccumulation and adverse effects of biomagnification by food chains. Given human experiments are facing ethical issues and animal studies cannot completely reveal human characteristics, advanced human organoids will provide promising models for MP/NP risk assessment. Moreover, in-depth investigations are required to identify the release of MPs/NPs from discarded face masks and characterize their transportation through the food chains. More importantly, innovative approaches and eco-friendly strategies are urgently demanded to reduce DFM-derived MP/NP pollution.