Mitigation measures to avert the impacts of plastics and microplastics in the marine environment (a review)

The plastic size spectra: Assessing the size structure of plastic particles across the land-water ecotone

Plastics of different types and sizes pollute most of Earth's environmental systems. Here, we used size spectra analysis (SSA) to evaluate and characterize size-frequency patterns of plastic pollution across the land-water ecotone of 20 urban lakes. We first tested the general hypothesis that plastic particles in the environment reflect a detectable and inverse size-frequency pattern as large plastics regularly breakdown in increasingly smaller pieces. To further evaluate the utility of SSA, we tested whether slope (λ) and intercept (Γ) coefficients from lake-specific models were sensitive to distinguish trends among lake zones. Overall, our findings detected an overall inverse relationship between particle counts (#/m2) and binned particle length, confirming the presence of a plastic size spectra for all aggregated data. We further improved the explanatory power of SSA models by (1) separating thin films from thicker plastic fragments and by (2) assessing sampling environments (i.e., upland vegetation, shoreline sediments, offshore sediments) separately. Doing so revealed statistically distinct size-frequency gradients that tracked the shift from land to water for both films and fragments. Analysis and comparison of SSA models also confirmed that coefficients were sensitive enough to detect differences among lake zones. All told, the SSA framework was successfully used to detect and describe several patterns of plastic pollution in the environment. This analytic framework holds promise for developing hypothesis-driven studies to all plastics rather than focusing on small or large particles.

Microplastic pollution: Critical analysis of global hotspots and their impact on health and ecosystems

This paper examines microplastic hotspots and their drastic effects on human health and the environment pointing out microplastic pollution as one of the biggest global issues. Besides, it analyses the key sources including industrial effluent discharge, littered plastic wastes, and deterioration of synthetic products together with pathways and routes of exposure. The review also focuses on microplastic contamination in food systems such as meat, plant-based products, dairy, and seafood, detailing their entry into the food chain via soil, water, and air. On the other hand, this work also focuses on human health issues including cellular absorption, and bioaccumulation, which results in tissue oxidative stress, inflammation, hormonal imbalance and adverse long-term effects, including carcinogenicity and organ toxicity. The ultimate effects of microplastic pollution on the condition of the soil, water, and fauna and flora of the ecosystem, highlighting on the need for the prevention measures, were also addressed. This paper seeks to critically ascertain the problems posed by microplastics, including their slow biodegradation limit, the absence of proper regulations, and lack of a universally accepted standard. It also highlights that microplastic pollution requires interdisciplinary analyses, future studies, and high standards-compliant policies and regulations. This work raises the alarm for a collective international effort to protect the public health, food, and the earth.

Seaweed as a sink for microplastic contamination: Uptake, identifications and food safety implications

Microplastics (MPs) are a rising global concern, infiltrating marine ecosystems and food sources, including seaweed, which is widely consumed. This review examines the prevalence of MPs in seaweed, their role as pathways for MPs to enter marine food webs, and the potential risks to marine organisms and human health. Findings indicate that it contributes up to 45.5 % of total dietary microplastic (MP) intake through seaweed, with particularly high levels in South Asian regions, which is concerning. Factors such as seaweeds morphology, surface properties, epibionts, and environmental conditions influence MP uptake. Microplastic contamination in seaweed leads to bioaccumulation and biomagnification, affecting marine organisms through oxidative stress, growth disruption, immune issues, and metabolic disturbances. Seaweeds bioaccumulate heavy metals from seawater, and microplastics (MPs) attract these metals, increasing toxicity might enter food chain posing health risk. Simple methods like water washing can reduce MPs on seaweed surfaces. However, in this case, innovative detection methods and advanced removal technologies are still underexplored. Similarly, Microplastic (MP) contamination presents economic risks to the global seaweed industry, valued at USD 7.0 billion in 2023, with exports reaching 819,100 tonnes worth USD 3.21 billion. By 2024, the industry, dominated by Asian countries, had grown to USD 22.13 billion, but MP contamination threatens further expansion by undermining consumer confidence, reducing market value, and increasing regulatory scrutiny. Asia accounts for 47.9 % of global seafood MP contamination, the economic repercussions could be substantial. Future research should explore the long-term effects of environmental aging on microplastic debris in seaweeds related marine organisms, emphasizing food security and human health. Studies should also focus on the toxicological effects of micro- and Nano plastics (MNPs) from seaweed-based contaminants in human food consumption. Robust government initiatives and policies promoting a circular economy are crucial for effective management.

Application of Computational Studies Using Density Functional Theory (DFT) to Evaluate the Catalytic Degradation of Polystyrene

The degradation of polystyrene (PS) represents a significant challenge in plastic waste management due to its chemical stability and low biodegradability. In this study, the catalytic degradation mechanisms of PS were investigated by density functional theory (DFT)-based calculations using the hybrid functional B3LYP and the 6-311G++(d,p) basis in Gaussian 16. The influence of acidic (AlCl3, Fe2(SO4)3) and basic (CaO) catalysts was evaluated in terms of activation energy, reaction mechanisms, and degradation products. The results revealed that acid catalysts induce PS fragmentation through the formation of carbocationic intermediates, promoting the selective cleavage of C-C bonds in branched chains with bond dissociation energies (BDE) of 176.8 kJ/mol (C1-C7) and 175.2 kJ/mol (C3-C8). In contrast, basic catalysts favor β-scission by stabilizing carbanions, reducing the BDE to 151.6 kJ/mol (C2-C3) and 143.9 kJ/mol (C3-C4), which facilitates the formation of aromatic products such as styrene and benzene. Fe2(SO4)3 was found to significantly decrease the activation barriers to 328.12 kJ/mol, while the basic catalysts reduce the energy barriers to 136.9 kJ/mol. Gibbs free energy (ΔG) calculations confirmed the most favorable routes, providing key information for the design of optimized catalysts in PS valorization. This study highlights the usefulness of computational modeling in the optimization of plastic recycling strategies, contributing to the development of more efficient and sustainable methods.

Who knows what a mask is … and what it does? A bibliometric and textometric study of more than a century of scientific publications on sanitary masks (1892-2023)

In this article, the authors identify the disciplines that have taken an interest in masks over time, as well as how, in what proportions, according to what concerns, with what developments, and possibly with what effects. They ask whether the multiplicity of disciplinary perspectives is likely to lead to the emergence and sharing of new concerns, especially environmental ones, or whether the balkanization and juxtaposition of disciplines may leave certain aspects in the dark and thus contribute to the persistent production of a certain kind of ignorance. Based on a bibliometric and textometric study of more than 6000 scientific articles (1892-2023), they show the extent to which the Covid-19 pandemic has turned the study of masks upside down. It has encouraged the development of multidisciplinary and even interdisciplinary approaches, even if the legacy of almost exclusively medical sciences and engineering tends to severely limit hybridizations. The study highlights the possible emergence of a new movement of 'scientization of the popular', which leads scientists to incorporate the everyday concerns of ordinary citizens into the conduct of their research, thus challenging and reversing the well-known process of popularizing science.

Opportunities and Challenges of a Cap-and-Trade System for Plastics

Recently, the rapid increase in global plastics production has caused various ecological and economic issues, worsened by poor material and waste management. Among the market-based instruments that could help mitigate the environmental impacts of plastics throughout their life-cycle, we evaluate the advantages and limitations of incorporating a cap-and-trade (CAT) system into future policy mixes. Our aim is to inspire further investigation of CAT's feasibility rather than presenting it as the ultimate solution. Drawing from past CAT implementations in domains such as water resource management and carbon emissions, we outline three key policy design considerations: (1) material and target group identification, (2) cap establishment and permit allocation, and (3) development of a competitive market environment. We explore a three-tiered approach with global, national, and sectoral caps covering the plastic lifecycle from cradle to grave. While there are viable reasons to consider a plastics CAT, significant challenges persist, which may ultimately limit its implementation. In the context of ongoing UN Plastics Treaty negotiations or future policy developments, this evaluation of CAT can be beneficial for assessing when and how this tool can address the negative externalities of plastics.

Physicochemical characteristics of airborne microplastics of a typical coastal city in the Yangtze River Delta Region, China

Airborne microplastics (MPs) are important pollutants that have been present in the environment for many years and are characterized by their universality, persistence, and potential toxicity. This study investigated the effects of terrestrial and marine transport of MPs in the atmosphere of a coastal city and compared the difference between daytime and nighttime. Laser direct infrared imaging (LDIR) and polarized light microscopy were used to characterize the physical and chemical properties of MPs, including number concentration, chemical types, shape, and size. Backward trajectories were used to distinguish the air masses from marine and terrestrial transport. Twenty chemical types were detected by LDIR, with rubber (16.7%) and phenol-formaldehyde resin (PFR; 14.8%) being major components. Three main morphological types of MPs were identified, and fragments (78.1%) are the dominant type. MPs in the atmosphere were concentrated in the small particle size segment (20-50 µm). The concentration of MPs in the air mass from marine transport was 14.7 items/m3 - lower than that from terrestrial transport (32.0 items/m3). The number concentration of airborne MPs was negatively correlated with relative humidity. MPs from terrestrial transport were mainly rubber (20.2%), while those from marine transport were mainly PFR (18%). MPs in the marine transport air mass were more aged and had a lower number concentration than those in the terrestrial transport air mass. The number concentration of airborne MPs is higher during the day than at night. These findings could contribute to the development of targeted control measures and methods to reduce MP pollution.

Degradable poly(β-amino ester) microparticles for cleansing products and food fortification

Microplastic pollution is a pressing global crisis caused by the extensive use of nondegradable microplastic materials in daily activities. One effective approach to mitigate this issue is to replace nondegradable plastics with degradable materials that have properties amendable for targeted applications. Here we present the development of a degradable microparticle (MP) platform based on a poly(β-amino ester) (PAE) that degrades into sugar and amino acid derivatives. This PAE MP platform showed functional replacement of nondegradable microplastics used in cleansing products and food fortification. In cleansing products, PAE MPs effectively enhanced the cleansing efficiency of a representative rinse-off product and showed effective removal of potentially toxic elements, as an alternative of traditional nondegradable microbeads. In food fortification, PAE MPs provided robust protection for multiple essential vitamins and minerals against extensive cooking and storage conditions with rapid nutrient release in a simulated human digestion system. Collectively, these PAE MPs present a potential platform to replace microplastic usage on a global scale in many applications.

Integrated transcriptomics and metabolomics reveal the mechanism of polystyrene nanoplastics toxicity to mice

Microplastic (MP) are an emerging environmental pollutant, which has toxic effects on organisms, and it has received extensive attention currently. Studying the transcriptomic and metabolic responses of mice to nanoplastic-contaminated water is critical for understanding molecular-level toxicity of nanoplastics (NPs), but there are few studies on this topic. To analyze the effects of different concentrations of polystyrene (PS) nanoplastic-contaminated water on mice at the transcriptome and metabolism of spleens to study the molecular toxicity. Here, testing of histopathology of spleen of female mice was performed after drinking water containing 0.1 μm PS-NPs (1 mg/mL and 50 mg/mL) at different concentrations for 49 days, respectively. The spleen tissue samples were subjected to metabolome and transcriptome sequencing. Four differentially expressed genes were randomly chosen for qRT-PCR to confirm the correctness of transcriptome sequencing. Common Kyoto encyclopedia of genes and genomes (KEGG) pathway analysis showed that a large number of differential genes and differential metabolites mainly focused on immune, inflammation, neurodegenerative disease, cardiovascular disease, nervous, etc. in the organism systems module; lipid, amino acid, taurine and hypotaurine metabolisms, etc. in the metabolism module; signaling translation, signaling molecules and interaction, and neuroactive ligand-receptor interaction, etc. in the environmental information processing. The results showed that pathway analysis at transcriptome and metabolome levels confirmed that the immune system of mice was affected after drinking water contaminated with polystyrene nanoplastics.

Addition of Coffee Waste-Derived Plasticizer Improves Processability and Barrier Properties of Poly(3-hydroxybutyrate-co-3-hydroxyvalerate)-Natural Rubber Bioplastic

This study aimed to develop a value-added bio-based polymer product for food packaging. Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) is a promising bioplastic with limitations in processability and brittleness, which our group previously addressed by incorporating high-molecular-weight natural rubber (NR) compatibilized with peroxide and coagent. Yet, processability in an industrial setting proved difficult. Coffee oil epoxide (COE), a waste-derived plasticizer, was incorporated into the PHBV/NR/peroxide/coagent matrix via extrusion, and properties of resulting sheets were evaluated. COE incorporation significantly decreased the oxygen and water permeability of the PHBV/NR sheets. Maximum degradation temperature Tpeak (°C) increased by ~4.6 °C, and degree of crystallinity decreased by ~15.5% relative to pristine PHBV, indicating good thermal stability. Melting (Tm) and glass transition temperatures (Tg) of the PHBV/NR blend remained unchanged with COE incorporation. X-ray diffraction (XRD) revealed ~10.36% decrease in crystal size for the plasticized blend. Energy-dispersive X-ray analysis (EDAX) and scanning electron microscopy (SEM) confirmed good dispersion with no phase separation. The water uptake capacity of the plasticized blend was reduced by 61.02%, while surface contact angle measurements showed improved water resistance. The plasticized PHBV sheet shows promise for environmentally friendly packaging films due to its high thermal stability, effective barrier properties, and industrial scalability.

Ecotoxicological evaluation of chitosan biopolymer films particles in adult zebrafish (Danio rerio): A comparative study with polystyrene microplastics

To mitigate the environmental impact of microplastics (MPs), the scientific community has innovated sustainable and biodegradable polymers as viable alternatives to traditional plastics. Chitosan, the deacetylated form of chitin, stands as one of the most thoroughly investigated biopolymers and has garnered significant interest due to its versatile applications in both medical and cosmetic fields. Nevertheless, there is still a knowledge gap regarding the impact that chitosan biopolymer films (CBPF) may generate in aquatic organisms. In light of the foregoing, this study aimed to assess and compare the potential effects of CBPF on the gastrointestinal tract, gills, brain, and liver of Danio rerio against those induced by MPs. The findings revealed that both CBPF and MPs induced changes in the levels of oxidative stress biomarkers across all organs. However, it is essential to note that our star plots illustrate a tendency for CBPF to activate antioxidant enzymes and for MPs to produce oxidative damage. Regarding gene expression, our findings indicate that MPs led to an up-regulation in the expression of genes associated with apoptotic response (p53, casp3, cas9, bax, and bcl2) in all fish organs. Meanwhile, CBPF produced the same effect in genes related to antioxidant response (nrf1 and nrf2). Overall, our histological observations substantiated these effects, revealing the presence of plastic particles and tissue alterations in the gills and gastrointestinal tract of fish subjected to MPs. From these results, it can be concluded that CBPF does not represent a risk to fish after long exposure.

Coastal groynes reduce beach litter accumulation along the East coast of England

Anthropogenic marine litter (AML) is a global environmental concern. One of the most conspicuous effects of AML is beach litter accumulation, the distribution of which is typically heterogenous. Little information is available on the potential effects of coastal topographic features on litter dispersal. We analysed the abundance, composition, and sources of beach litter on the East coast of England in relation to the presence of coastal groyne structures. Six beaches were surveyed in autumn and winter 2021 using the OSPAR methodology for monitoring beach litter. Litter abundance was lower on beaches with groynes present, which could infer that groynes deflect or bury AML. The presence of groynes had no significant effect on the composition/sources of beach litter. Single-use plastic packaging, fishing waste, and sewage-related debris were the largest contributors of beach litter in this region. Our findings indicate that man-made topographic features may affect marine litter dispersal and coastal accumulation.

Exploring seasonal, spatial and pathways of marine litter pollution along the Southeastern Black Sea Cost of Türkiye

Spatial and temporal variations in marine litter density and composition along the Southeastern Black Sea Coast were investigated. A total of 156,371 litter items weighing 327,258.3 kg were collected. The highest frequency of litter material by number was 15,869 ± 103.88 items/m2 16 and 74.466 ± 7.23 by weight. The highest litter concentrations (77,768 items; 81,737.1 kg) were observed in autumn, mainly comprising single-use items, with plastic being the most abundant (54.05 %), followed by metal (15.69 %), and paper (10.45 %). The subcategories of plastic litter items bags, caps/lids, cigarette lighters, cosmetic packages, gloves, and plastics pieces were found to be the most abundant litter in number. According to Principal Component Analysis (PCA) and Kruskal-Wallis statistical tests (p < 0.005), significant differences in marine litter were identified among the stations and seasons. These findings offer insights for modeling studies, advocating restrictions on single-use products, and enacting legal regulations for local governance.

Microplastics in Ecuador: A review of environmental and health-risk assessment challenges

Pollution from plastic debris and microplastics (MPs) is a worldwide issue. Classified as emerging contaminants, MPs have become widespread and have been found not only in terrestrial and aquatic ecosystems but also within the food chain, which affects both the environment and human health. Since the outbreak of COVID-19, the consumption of single-use plastics has drastically increased, intensifying mismanaged plastic waste in countries such as Ecuador. Therefore, the aim of this review is to 1) summarize the state of MP-related knowledge, focusing on studies conducted with environmental matrices, biota, and food, and 2) analyze the efforts by different national authorities and entities in Ecuador to control MP contamination. Results showed a limited number of studies have been done in Ecuador, which have mainly focused on the surface water of coastal areas, followed by studies on sediment and food. MPs were identified in all samples, indicating the lack of wastewater management policies, deficient management of solid wastes, and the contribution of anthropogenic activities such as artisanal fishing and aquaculture to water ecosystem pollution, which affects food webs. Moreover, studies have shown that food contamination can occur through atmospheric deposition of MPs; however, ingredients and inputs from food production, processing, and packaging, as well as food containers, contribute to MP occurrence in food. Further research is needed to develop more sensitive, precise, and reliable detection methods and assess MPs' impact on terrestrial and aquatic ecosystems, biota, and human health. In Ecuador specifically, implementing wastewater treatment plants in major cities, continuously monitoring MP coastal contamination, and establishing environmental and food safety regulations are crucial. Additionally, national authorities need to develop programs to raise public awareness of plastic use and its environmental effects, as well as MP exposure's effects on human health.

Meso- and microplastic composition, distribution patterns and drivers: A snapshot of plastic pollution on Brazilian beaches

Pollution by plastics is a worldwide problem on par with climatic change and biological invasions. In coastal sediments, plastic particles tend to accumulate and persist over the long term. We assessed the plastic pollution using a standardized surface sediment sampling protocol on 22 sandy beaches along >4600 km of the Brazilian coast. The abundance, size, color, type, and polymeric composition of all meso- and microplastic items found in the surveys were processed to disclose spatial patterns of distribution and pollution associated drivers. A General Linear Model (GLM) was run to investigate how the predictor variables influenced overall beach plastic amounts and by plastic type and size class. Overall, 3114 plastic items were found, with microplastics comprising just over half of all items (54 %). Most items were either white (60 %) or blue (13 %), while polystyrene foam (45 %) and fragments (39 %) comprised the most abundant plastic types. The principal polymers were Polyethylene (40 %) and Polypropylene (32 %). The analyses indicated that the distribution of plastic litter along beaches is determined by three predictive variables: the distance to the nearest estuary (-), tourism (+), and the number of inhabitants in the nearest urban center (+). Tourist (highly-visited) beaches and those near estuarine runoffs or urban centers presented the highest plastic pollution rates. The unveiling of plastic pollution patterns through a large-scale systematic survey is essential for future management guidance and science-based decisions for mitigating and solving the plastic pollution crisis.

Evaluation of possible attenuative role of chrysoeriol against polyethylene microplastics instigated testicular damage: A biochemical, spermatogenic and histological study

The current study was designed to evaluate the protective role of chrysoeriol against polyethylene microplastics (PE-MP) induced testicular damage. Forty eight male rats were distributed into 4 equal groups: vehicle control, PE-MP administrated, PE-MP + chrysoeriol co-administrated and only chrysoeriol supplemented group. The administration of PE-MP significantly reduced the activities of anti-oxidant enzymes, i.e., glutathione peroxidase, catalase, glutathione reductase and superoxide dismutase, whereas the levels of reactive oxygen species and malondialdehyde were increased. PE-MP exposure increased the levels of inflammatory markers (TNF-α, 1L-1β, NF-κβ, IL-6 & COX-2). Additionally, a considerable increase was observed in dead sperms number, abnormality of sperms (tail, midpiece and head), while a potential decrease was noticed in sperm motility in PE-MP treated rats. The expressions of steroidogenic enzymes were also decreased in PE-MP administrated group. The levels of plasma testosterone, luteinizing & follicle stimulating hormone were decreased in PE-MP treated group. Moreover, Bax and Caspase-3 expressions were increased, whereas Bcl-2 expressions were reduced. Furthermore, histopathological analysis showed that PE-MP exposure considerably damaged the testicular tissues. However, chrysoeriol supplementation potentially decreased all the adverse effects induced by PE-MP. Taken together, our findings indicate that chrysoeriol holds significant potential to avert PE-MP-induced testicular damage due to its androgenic, anti-apoptotic, anti-oxidant and anti-inflammatory nature.

From oceans to dinner plates: The impact of microplastics on human health

Microplastics, measuring less than 5 mm in diameter, are now found in various environmental media, including soil, water, and air, and have infiltrated the food chain, ultimately becoming a part of the human diet. This study offers a comprehensive examination of the intricate nexus between microplastics and human health, thereby contributing to the existing knowledge on the subject. Sources of microplastics, including microfibers from textiles, personal care products, and wastewater treatment plants, among others, were assessed. The study meticulously examined the diverse routes of microplastic exposure-ingestion, inhalation, and dermal contact-offering insights into the associated health risks. Notably, ingestion of microplastics has been linked to gastrointestinal disturbances, endocrine disruption, and the potential transmission of pathogenic bacteria. Inhalation of airborne microplastics emerges as a critical concern, with possible implications for respiratory and cardiovascular health. Dermal contact, although less explored, raises the prospect of skin irritation and allergic reactions. The impacts of COVID-19 on microplastic pollution were also highlighted. Throughout the manuscript, the need for a deeper mechanistic understanding of microplastic interactions with human systems is emphasized, underscoring the urgency for further research and public awareness.

Microplastics in the marine environment of St. Mary's Island: implications for human health and conservation

Microplastics have now been identified as a class of emerging pollutants and is considered as a threat to aquatic organisms. This baseline paper investigated the distribution, composition, and potential ecological risks of microplastic (MP) pollution on St. Mary's Island, revealing an average abundance of 0.218 particles/L in water samples. Blue fibres and white foams were the primary MPs identified, and fishing activities and packaging were the main sources of pollution. Six types of polymers were identified: low-density polyethylene (LDPE), polystyrene (PS), polyamide (PA), polypropylene (PP), polyethylene (PE), and high-density polyethylene (HDPE). The Polymer Hazard Index (PHI) and Potential Ecological Risk Index (PERI) indicated a medium environmental risk for the island. Additionally, it was discovered that MPs' surfaces contained dangerous substances that could endanger aquatic life. The research emphasizes the significance of implementing measures such as responsible disposal, management, elimination, regulatory policies, and local administration techniques to mitigate the impact of MP pollution on the island's shores and marine biota. This research provides a baseline for monitoring MP contamination and underscores the need for continuous investigation to assess their impacts on marine life.

Source, occurrence, distribution, fate, and implications of microplastic pollutants in freshwater on environment: A critical review and way forward

The generation of microplastics (MPs) has increased recently and become an emerging issue globally. Due to their long-term durability and capability of traveling between different habitats in air, water, and soil, MPs presence in freshwater ecosystem threatens the environment with respect to its quality, biotic life, and sustainability. Although many previous works have been undertaken on the MPs pollution in the marine system recently, none of the study has covered the scope of MPs pollution in the freshwater. To consolidate scattered knowledge in the literature body into one place, this work identifies the sources, fate, occurrence, transport pathways, and distribution of MPs pollution in the aquatic system with respect to their impacts on biotic life, degradation, and detection techniques. This article also discusses the environmental implications of MPs pollution in the freshwater ecosystems. Certain techniques for identifying MPs and their limitations in applications are presented. Through a literature survey of over 276 published articles (2000-2023), this study presents an overview of solutions to the MP pollution, while identifying research gaps in the body of knowledge for further work. It is conclusive from this review that the MPs exist in the freshwater due to an improper littering of plastic waste and its degradation into smaller particles. Approximately 15-51 trillion MP particles have accumulated in the oceans with their weight ranging between 93,000 and 236,000 metric ton (Mt), while about 19-23 Mt of plastic waste was released into rivers in 2016, which was projected to increase up to 53 Mt by 2030. A subsequent degradation of MPs in the aquatic environment results in the generation of NPs with size ranging from 1 to 1000 nm. It is expected that this work facilitates stakeholders to understand the multi-aspects of MPs pollution in the freshwater and recommends policy actions to implement sustainable solutions to this environmental problem.

Assessing the effectiveness of MARPOL Annex V at reducing marine debris on Australian beaches

To mitigate marine debris and promote sustainable marine industries, legislation and regulations surrounding the management of marine debris have been adopted worldwide. One of the most well-known and important agreements is the International Convention for the Prevention of Pollution from Ships (MARPOL), which focuses on reducing all types of ship-sourced marine pollution. MARPOL Annex V, which deals with the disposal of solid waste, came into force on 31 December 1988. However, was only amended to include a complete ban on waste disposal as of 1 January 2013. Assessing the effectiveness of key regulations is fundamental for supporting evidence-based decisions regarding the management of our oceans. Here, we evaluated whether MARPOL Annex V translated into a decrease in the incidence of shipping- and commercial fishing-sourced debris on remote beaches in Australia using 14 years of standardised, community-driven data. From 2006 to 2020 there was a significant change over time in the density of fishing and shipping debris on Australian beaches; debris density increased up to 2013 followed by a decrease until mid-2017. Although the new regulation started in January 2013, the decrease in density was not recorded until one year later. The decline was only observed for 4 years, reinforcing the existence of lags between the implementation of international agreements and the corresponding potential reduction in debris in the environment. This provides compelling evidence that international agreements and policies by themselves are not enough to solve the debris problem, with improved implementation and enforcement also required. We discuss future perspectives and solutions to reduce ocean-sourced litter inputs into the ocean and highlight the urgent need for action.

Consumer Awareness of Plastic: an Overview of Different Research Areas

Plastic makes our society more practical and safer. It is hard to consider eliminating plastic in some sectors, such as the medical field. However, after use, plastic waste becomes a global problem without precedents, and when not properly disposed of, it can cause several socio-environmental problems. Some possible solutions are recycling, the circular economy, proper waste management, and consumer awareness. Consumers play a crucial role in preventing problems caused by plastic. In this work, consumer awareness of plastic is discussed according to the point of view of the research areas-environmental science, engineering, and materials science-based on the analysis of the main authors' keywords obtained in a literature search in the Scopus database. Bibliometrix analyzed the Scopus search results. The results showed that each area presents different concerns and priorities. The current scenario, including the main hotspots, trends, emerging topics, and deficiencies, was obtained. On the contrary, the concerns from the literature and those of the daily lives of consumers do not seem to fit in, which creates a gap. By reducing this gap, the distance between consumers awareness and their behavior will be smaller.

Facemask: Protection or threat?

Facemasks were widely used as a protection against SARS-COV-2, which significantly reduced COVID-19 transmission during the pandemic. However, concerns have been raised regarding its adverse impacts on human health due to intense use and mismanagement. Although rampant plastic littering was the norm before the pandemic, the magnitude of the problem is worsening as potentially COVID-19-infected facemasks are thrown along the shoreline. This study assessed the discarded facemasks on the most popular beach destinations in Mati City, Davao Oriental, Philippines. A total of N = 284 discarded facemasks were found in a cumulative area of 22,500 m2, with an average density of 8.4 × 10-4 items/m2. The surgical facemask (82 %; n = 234) was the most abundant type of facemask found in the areas, followed by KF94 (16 %; n = 45) and KN95 (2 %; n = 5). The Analysis of Variance (ANOVA) showed significant differences in the visual counts of facemasks on the three beaches (p < 0.05).

Current research trends on cosmetic microplastic pollution and its impacts on the ecosystem: A review

Since the advent of microplastics, it has become a vital component, directly or indirectly, in our daily lives. With advancements in their use, microplastics have become an integral part of personal care, cosmetics, and cleaning products (PCCPs) and emerged as a domestic source of environmental pollution. Over the years, researchers have ascertained the harmful effects of microplastics on the environment. In this context, the assessment and monitoring of microplastics in PCCPs require considerable attention. In addition, it raises concern regarding the need to develop innovative, sustainable, and environmentally safe technologies to combat microplastic pollution. Therefore, this review is an endeavor to uncover the fate, route and degradation mechanism of cosmetic microplastics. In addition, the major technological advancement in cosmetic microplastic removal and the steps directed toward mitigating cosmetic microplastic pollution are also discussed.

Carboxymethylcellulose/agar-based functional film incorporated with nitrogen-doped polyethylene glycol-derived carbon dots for active packaging applications

The present investigation demonstrates the role of nitrogen doping on polyethylene glycol (PEG)-derived carbon dots on optical, antibacterial, and antioxidant activity. CDs' average size and surface charge were determined using transmission electron microscopy (TEM) and a zeta sizer with 2.14 ± 0.6 nm and -20 mV, respectively. Though CDs without N-doping (PCD) did not show any significant antioxidant and antimicrobial activities, the CDs doped with nitrogen (NPCD) showed potent antioxidant (25% and 100% DPPH and ABTS radical scavenging activity) and significant antimicrobial activity against Gram-positive (1.8 cm inhibition zone) and Gram-negative (1.4 cm) bacteria. Both carbon dots were loaded into the carboxymethyl cellulose (CMC)/agar-based film with different concentrations (4 and 8%) and showed a significant increase in the physicochemical properties, and UV-blocking property was increased from 53.7 to 79.9% without sacrificing the transparency. The NPCD-loaded film also showed high antioxidant (DPPH 12.7% and ABTS 67%) and potent antibacterial activity. In particular, the CMC/agar film loaded with 8% NPCD destroyed Escherichia coli and Listeria monocytogenes completely after 6 h of incubation.

Co-processing of plastic waste in a cement kiln: a better option

This paper deals with the techniques to use plastic waste for co-processing in cement kiln for energy recovery. Plastics, a versatile material and friend to the common man, have now become one of the most serious environmental issues when it is discarded into the environment. The focus of this study is on eco-friendly disposal of plastic waste. Plastic is user-friendly, but because of its incomplete lifecycle, it has become a global issue. It is commonly disposed of by land filling or incinerating the waste, which adds to the pollution load at later stages. The authors' focus is on innovative techniques to use waste plastics in different proportions for the co-processing in cement kiln in order to highlight the energy recovery of the entire plant. It is a good solution to the waste disposal problems that arise due to plastic waste as well as municipal solid waste. The use of plastic waste as an alternative fuel for cement plants is suggested in this paper. The authors also promote this approach and suggest encouraging its calorific value utilization in the cement manufacturing plant. A systematic approach has been presented in this work to mitigate the energy consumption in the cement industries as well as environmental hazards due to plastic and municipal solid waste.

Plastic Waste: Challenges and Opportunities to Mitigate Pollution and Effective Management

The present world is now facing the challenge of proper management and resource recovery of the enormous amount of plastic waste. Lack of technical skills for managing hazardous waste, insufficient infrastructure development for recycling and recovery, and above all, lack of awareness of the rules and regulations are the key factors behind this massive pile of plastic waste. The severity of plastic pollution exerts an adverse effect on the environment and total ecosystem. In this study, a comprehensive analysis of plastic waste generation, as well as its effect on the human being and ecological system, is discussed in terms of source identification with respect to developed and developing countries. A detailed review of the existing waste to energy and product conversion strategies is presented in this study. Moreover, this study sheds light on sustainable waste management procedures and identifies the key challenges to adopting effective measures to minimise the negative impact of plastic waste.

An Overview into Polyethylene Terephthalate (PET) Hydrolases and Efforts in Tailoring Enzymes for Improved Plastic Degradation

Plastic or microplastic pollution is a global threat affecting ecosystems, with the current generation reaching as much as 400 metric tons per/year. Soil ecosystems comprising agricultural lands act as microplastics sinks, though the impact could be unexpectedly more far-reaching. This is troubling as most plastic forms, such as polyethylene terephthalate (PET), formed from polymerized terephthalic acid (TPA) and ethylene glycol (EG) monomers, are non-biodegradable environmental pollutants. The current approach to use mechanical, thermal, and chemical-based treatments to reduce PET waste remains cost-prohibitive and could potentially produce toxic secondary pollutants. Thus, better remediation methods must be developed to deal with plastic pollutants in marine and terrestrial environments. Enzymatic treatments could be a plausible avenue to overcome plastic pollutants, given the near-ambient conditions under which enzymes function without the need for chemicals. The discovery of several PET hydrolases, along with further modification of the enzymes, has considerably aided efforts to improve their ability to degrade the ester bond of PET. Hence, this review emphasizes PET-degrading microbial hydrolases and their contribution to alleviating environmental microplastics. Information on the molecular and degradation mechanisms of PET is also highlighted in this review, which might be useful in the future rational engineering of PET-hydrolyzing enzymes.

Derivatives of Plastics as Potential Carcinogenic Factors: The Current State of Knowledge

Simple Summary

Nowadays, micro- and nanoplastic particles can be found almost everywhere, being especially harmful for humans. Their absorption, primarily via inhalation and digestive routes, might lead to a particularly dangerous accumulation of those substances within the human body. Due to the alarming increase in contamination worldwide and excessive production of plastics and synthetic materials, there is an urgent need to investigate the effects of those substances on human health. So far, it has been observed that nano- and microplastics might be extremely harmful, leading to serious health conditions, such as cancers of various human body systems.

Abstract

Micro- and nanoplatics have been already reported to be potential carcinogenic/mutagenic substances that might cause DNA damage, leading to carcinogenesis. Thus, the effects of micro- and nanoplastics exposure on human health are currently being investigated extensively to establish clear relationships between those substances and health consequences. So far, it has been observed that there exists a definite correlation between exposure to micro- and nanoplastic particles and the onset of several cancers. Therefore, we have conducted research using PubMed, Web of Science, and Scopus databases, searching for all the research papers devoted to cancers that could be potentially related to the subject of exposure to nano- and microplastics. Ultimately, in this paper, we have discussed several cancers, including hepatocellular carcinoma, pancreatic cancer, pancreatic ductal adenocarcinoma, biliary tract cancer, and some endocrine-related cancers.

Developing the Use of Wool Rope within Aquaculture—A Systematic Review

To date, wool is an underutilised sustainable resource that has the potential to reduce the use of plastic within the environment. Wool can be manufactured as rope, but is this a viable innovation? To gain a comprehensive understanding of the economic viability of utilising wool rope in seaweed aquaculture, a systematic literature review was undertaken. The review focuses on wool, rope, natural and man-made fibres and seaweed farming, and used bibliometric and content analysis of peer-reviewed papers, with no timeframe requirements. It is important to explore alternative materials to reduce marine rope pollution; ghost gear, microplastics from abrasion and plasticrusts are now believed to be significant ecological problems. To date, the production of wool rope is limited, and its strength and durability within the fishing industry remain untested. It is important to understand whether wool rope is a useful alternative: does it have the same tensile strength, and can it be used within the industry without the risk of damage to the environment? There is currently a lack of research on natural rope fibres, resulting in limited access to commercial rope alternatives being used within the industry. This systematic review shows that there has been a large gap in wool research, with limited publications in recent years; however, the drive to increase sustainability (particularly within the marine environment) has increased. This is the first paper that combines both topics within one research study. Further research is needed to identify whether wool rope will provide a feasible alternative to polypropylene in terms of strength and durability, and how wool rope will perform, the length of time it can provide optimum service and within which seaweed farming practice it can offer a practical alternative to polypropylene.

The spatial and temporal changes of beach litter on Istanbul (Turkey) beaches as measured by the clean-coast index

Possible access routes of macro and mesoplastics, acting as the main sources of pollution in the coastal ecosystem, are examined as a case study on four beaches along the Istanbul coast. A total number of 3787 items belonging to 12 categories of debris types were collected as follows: macroplastics 47.8%; mesoplastics 9.2%; and others 43.0% such as paper pieces, glass pieces and metal beverage cans. Clean-coast and carbonyl indexes were also used to identify the level of cleanliness of the sampling sites. The clean-coast index revealed that all of the sample sites were categorized as extremely dirty. Moreover, carbonyl index results indicate that 35.7% of the samples were at a high oxidation level indicating that some of the particles relatively spend more time on beaches. The litter concentration and surface oxidation results were addressing issues that should be taken into consideration to improve litter management strategies of the beaches.

Emerging investigator series: microplastic sources, fate, toxicity, detection, and interactions with micropollutants in aquatic ecosystems - a review of reviews

Hundreds of review studies have been published focusing on microplastics (MPs) and their environmental impacts. With the microbiota colonization of MPs being firmly established, MPs became an important carrier for contaminants to step inside the food web all the way up to humans. Thus, the continuous feed of MPs into the ecosystem has sparked a multitude of scientific concerns about their toxicity, characterization, and interactions with microorganisms and other contaminants. The reports of common subthemes have agreed about many findings and research gaps but also showed contradictions about others. To unravel these equivocal conflicts, we herein compile all the major findings and analyze the paramount discrepancies among these review papers. Furthermore, we systematically reviewed all the highlights, research gaps, concerns, and future needs. The covered focus areas of MPs' literature include the sources, occurrence, fate, existence, and removal in wastewater treatment plants (WWTPs), toxicity, interaction with microbiota, sampling, characterization, data quality, and interaction with other co-contaminants. This study reveals that many mechanisms of MPs' behavior in aquatic environments like degradation and interaction with microbiota are yet to be comprehended. Furthermore, we emphasize the critical need to standardize methods and parameters for MP characterization to improve the comparability and reproducibility of the incoming research.

Environmental Impacts of Microplastics and Nanoplastics: A Current Overview

The increasing distribution of miniaturized plastic particles, viz. microplastics (100 nm–5 mm) and nanoplastics (less than 100 nm), across the various ecosystems is currently a subject of major environmental concern. Exacerbating these concerns is the fact that microplastics and nanoplastics (MNPs) display different properties from their corresponding bulk materials; thus, not much is understood about their full biological and ecological implications. Currently, there is evidence to prove that these miniaturized plastic particles release toxic plastic additives and can adsorb various chemicals, thereby serving as sinks for various poisonous compounds, enhancing their bioavailability, toxicity, and transportation. Furthermore, there is a potential danger for the trophic transfer of MNPs to humans and other higher animals, after being ingested by lower organisms. Thus, this paper critically analyzes our current knowledge with regard to the environmental impacts of MNPs. In this regard, the properties, sources, and damaging effects of MNPs on different habitats, particularly on the biotic components, were elucidated. Similarly, the consequent detrimental effects of these particles on humans as well as the current and future efforts at mitigating these detrimental effects were discussed. Finally, the self-cleaning efforts of the planet via a range of saprophytic organisms on these synthetic particles were also highlighted.

Microplastics (MPs) Act as Sources and Vector of Pollutants-Impact Hazards and Preventive Measures

Currently, people are paying more and more attention to the interaction between microplastics (MPs) and chemical substances (including metals and organic substances), so it is necessary to understand the relationship between MPs and chemical substances. In this review, we explored (1) MPs may become a source of chemical substances. (2) MPs can also be used as a carrier for attaching pollutants. (3) No matter what role MPs play, MPs and the attached chemical substances will have harmful effects on biological systems. However, because the current research is not deep enough, more experimental areas are needed to explore the interaction mechanism and the principle of toxicity. In addition, laws and policies need to be developed that actively promote and strive to develop biodegradable alternative microplastics to reduce the harm of microplastics and their additives to the environment.

Microplastics in Florida, United States: A Case Study of Quantification and Characterization With Intertidal Snails

Concentrations of microplastics are increasing within the oceans, including waters surrounding Florida, United States. Miles of sandy beaches make the sunshine state a prime tourist destination leading to an increased amount of pollution along Florida coasts. Microplastics can cause damage to intertidal organisms, as well as causing issues up the food chain with biomagnification and seafood consumers, such as humans. Florida is also subject to hurricanes which often distribute sediments, filling the water column with previously settled microplastics. These factors make Florida a special case to review considering the state is affected heavily by hurricanes and tourism, which can contribute to microplastic concentrations in the Gulf of Mexico. The focus of this study was to quantify, characterize, and compare microplastics contamination in two predatory marine snail species from intertidal habitats in Florida, United States Ingestion results were also compared to microplastics contamination of water samples collected from the same locations. Red-mouth rock shell (Stramonita haemastoma, n = 30) and Crown conch (Melongena corona, n = 30) snails were collected from intertidal habitats in Florida and digested for microplastics quantification. Water samples were filtered and microplastics were quantified. 256 microplastics, of which 93% were microfibers and 7% were microfragments were isolated from snails (n = 60). Additionally, 67 microplastics were isolated from 8 L of seawater (8.375 microplastics/L), of which 97% were microfibers and 3% were microfragments. This is the first known study to demonstrate microplastics contamination of tissues in predatory marine intertidal snails. Marine intertidal snails may be good organisms for biomonitoring of microplastics in intertidal sandy habitats.

Screening Method for Polyhydroxyalkanoate Synthase Mutants Based on Polyester Degree of Polymerization Using High-Performance Liquid Chromatography

A high-throughput screening method based on the degree of polymerization (DP) of polyhydroxyalkanoate (PHA) was developed using high-performance liquid chromatography (HPLC). In this method, PHA production was achieved using recombinant Escherichia coli supplemented with benzyl alcohol as a chain terminal compound. The cultured cells containing benzyl alcohol-capped PHA were decomposed by alkaline treatment, and the peaks of the decomposed monomer and benzyl alcohol were detected using HPLC. The DP of PHA could be determined from the peak ratio of the decomposed monomer to terminal benzyl alcohol. The measured DP was validated by other instrumental analyses using purified PHA samples. Using this system, mutants of PHA synthase from Bacillus cereus YB-4 (PhaRC_YB4) were screened, and some enzymes capable of producing PHA with higher DP than the wild-type enzyme were obtained. The PHA yields of two of these enzymes were equivalent to the yield of the wild-type enzyme. Therefore, this screening method is suitable for the selection of beneficial mutants that can produce high molecular weight PHAs.

Impacts of Plastic Pollution on Ecosystem Services, Sustainable Development Goals, and Need to Focus on Circular Economy and Policy Interventions

Plastic pollution is ubiquitous in terrestrial and aquatic ecosystems. Plastic waste exposed to the environment creates problems and is of significant concern for all life forms. Plastic production and accumulation in the natural environment are occurring at an unprecedented rate due to indiscriminate use, inadequate recycling, and deposits in landfills. In 2019, the global production of plastic was at 370 million tons, with only 9% of it being recycled, 12% being incinerated, and the remaining left in the environment or landfills. The leakage of plastic wastes into terrestrial and aquatic ecosystems is occurring at an unprecedented rate. The management of plastic waste is a challenging problem for researchers, policymakers, citizens, and other stakeholders. Therefore, here, we summarize the current understanding and concerns of plastics pollution (microplastics or nanoplastics) on natural ecosystems. The overall goal of this review is to provide background assessment on the adverse effects of plastic pollution on natural ecosystems; interlink the management of plastic pollution with sustainable development goals; address the policy initiatives under transdisciplinary approaches through life cycle assessment, circular economy, and sustainability; identify the knowledge gaps; and provide current policy recommendations. Plastic waste management through community involvement and socio-economic inputs in different countries are presented and discussed. Plastic ban policies and public awareness are likely the major mitigation interventions. The need for life cycle assessment and circularity to assess the potential environmental impacts and resources used throughout a plastic product’s life span is emphasized. Innovations are needed to reduce, reuse, recycle, and recover plastics and find eco-friendly replacements for plastics. Empowering and educating communities and citizens to act collectively to minimize plastic pollution and use alternative options for plastics must be promoted and enforced. Plastic pollution is a global concern that must be addressed collectively with the utmost priority.

Effects induced by polyethylene microplastics oral exposure on colon mucin release, inflammation, gut microflora composition and metabolism in mice

Microplastics are plastic fragments widely distributed in the environment and accumulate in the organisms. However, the research on microplastics effects in mammals is limited. Polyethylene is the main kind of microplastics in the environment. We hypothesized that polyethylene exposure disrupts host intestine metabolism by modifying intestine microflora composition and then lipopolysaccharide (LPS) pathway. Female mice were orally exposed to 0, 0.002 and 0.2 μg/g/d polyethylene microplastics (PE MPs) for 30 days. Colon mucin density was quantized after AB-PAS staining. Mucin 2 (MUC2), inflammatory factors (IL-1β, IL-6, IL-8 and IL-10), short-chain fatty acid receptors (GPR41 and GPR43), LPS receptors (TLR4 and MyD88) and LPS pathway downstream genes (ERK1 and NF-κB) mRNA levels in colon were measured. Feces were collected on the 15th day of exposure for gut microflora analysis. Blood biochemical analysis was performed. Results showed that 0.2 μg/g/d PE MPs exposure significantly decreased colon mucin expression (p < 0.05), decreased IL-1β (p < 0.05) and increased IL-8 and IL-10 levels (p < 0.01 and p < 0.001 respectively). Microflora data showed that in 0.2 μg/g/d PE MPs group the number of Firmicutes decreased and the number of Bacteroides increased (both p < 0.01). Predicted KEGG metabolic pathways by piecrust method indicated that PE MPs enhanced amino acids metabolism in microflora. ERK1 and NF-κB mRNA were significantly lower in 0.2 μg/g/d PE MPs group (both p < 0.001). Blood total protein, albumin and globulin levels significantly increased after 0.2 μg/g/d PE MPs exposure (p < 0.01, p < 0.01 and p < 0.05 respectively). These results indicate that PE MPs exposure induced decreased mucin production, a slight immune response and increased the microflora amino acid metabolism in the mice colon by modifying colon microflora composition. SUMMARY: Polyethylene microplastics exposure decreased colon mucin release and increased amino acid metabolism by modifying colon microflora composition.

Plastic and its consequences during the COVID-19 pandemic

During the pandemic outbreak of COVID-19, the important role of plastic becomes evident since vital equipment such as respirators have plastic parts, as well as personal protective equipment (PPE), which avoids the transmission of the SARS-CoV-2 virus, is made of plastic. So, plastic during a pandemic is considered a life savior in the struggle against the virus. However, the same material that is a protector becomes a polluter when inadequately disposed of in the environment, generating or worsening socio-environmental problems, such as pollution of water bodies by plastic. This work proposes a reflection about the role and the importance of plastic in our society, bringing an overview of its main applications and consequences during the COVID-19 pandemic, correlating its use with aspects related to environmental problems and public health. Some questions revolving around the concerns caused by plastic pollution are posed, and some possible solutions to the problems are outlined.

Plastic and its consequences during the COVID-19 pandemic

During the pandemic outbreak of COVID-19, the important role of plastic becomes evident since vital equipment such as respirators have plastic parts, as well as personal protective equipment (PPE), which avoids the transmission of the SARS-CoV-2 virus, is made of plastic. So, plastic during a pandemic is considered a life savior in the struggle against the virus. However, the same material that is a protector becomes a polluter when inadequately disposed of in the environment, generating or worsening socio-environmental problems, such as pollution of water bodies by plastic. This work proposes a reflection about the role and the importance of plastic in our society, bringing an overview of its main applications and consequences during the COVID-19 pandemic, correlating its use with aspects related to environmental problems and public health. Some questions revolving around the concerns caused by plastic pollution are posed, and some possible solutions to the problems are outlined.

Ocean plastics: environmental implications and potential routes for mitigation - a perspective

This review provides a current summary of the major sources and distribution of ocean plastic contamination, their potential environmental effects, and prospects towards the mitigation of plastic pollution. A characterization between micro and macro plastics has been established, along with a comprehensive discussion of the most common plastic waste sources that end up in aquatic environments within these categories. Distribution of these sources stems mainly from improper waste management, road runoff, and wastewater pathways, along with potential routes of prevention. The environmental impact of ocean plastics is not yet fully understood, and as such, current research on the potential adverse health effects and impact on marine habitats has been discussed. With increasing environmental damage and economic losses estimated at $US 1.5 trillion, the challenge of ocean plastics needs to be at the forefront of political and societal discussions. Efforts to increase the feasibility of collected ocean plastics through value-added commercial products and development of an international supply chain has been explored. An integrative, global approach towards addressing the growing ocean plastic problem has been presented.

Solid waste: An overlooked source of microplastics to the environment

Microplastics pollution is one of the most pressing environmental problems of the 21st century. While microplastics are pervasive throughout various environmental compartments, research to date has primarily focused on marine systems. Land-based microplastics sources (e.g., solid waste) have received comparatively little attention, although they account for the main flow of microplastics into aquatic environments. Solid waste microplastics sources primarily include landfill refuse, sludge, and food waste. Microplastics in these waste streams can be associated with various micropollutants that can have deleterious impacts on ecosystem health as they enter the food chain. Thus, understanding the occurrence, fate, and degradation pathways of solid waste microplastics is essential to develop comprehensive control and mitigation strategies. This study critically reviewed these key aspects of microplastics in municipal solid waste landfill refuse, sewage sludge, and food waste, and identified the interconnections of these components in the proliferation of microplastics to the environment. Additionally, microplastics related laws and regulations and their relevance to solid waste microplastics mitigation are discussed.

Potential effects of biodegradable single-use items in the sea: Polylactic acid (PLA) and solitary ascidians

With conventional plastics posing a great threat to marine organisms, and potentially also to humans, bio-based, biodegradable plastics are being offered as an ecological solution by which to reduce the environmental impact. Inside compost facilities, bioplastics that comply with the EN 13432:2000 international standard biodegrade almost completely within 180 days. However, outside compost facilities, and specifically in marine environments, these bioplastics may have a similar effect to that of fossil-fuel based plastics. Here we investigated the effects of polyethylene terephthalate (PET) and polylactic acid (PLA) single-use cups and plates on a solitary ascidian's biological and ecological features. Both PET and PLA microparticles reduced the fertilization rate of Microcosmus exasperatus, with no significant difference between materials. Accumulation rates in adult M. exasperatus exposed to micronized PET and PLA particles at two concentrations were similar for both the bioplastic material and the conventional plastic particles, with no significant difference between the two materials. A microbial-based digestive protocol was developed in order to recover the bioplastic material from ascidian tissue and reduce any material-loss caused by the known digestion protocols. Finally, PET plates submerged for three months in the Red Sea exhibited a significantly higher community richness and cover area in comparison to PLA plates, which did not provide a firm substrate for settlers. Indeed, coverage by the solitary ascidian Herdmania momus was significantly higher on PET plates. The current study demonstrates that discarded bioplastic products may have similar effects to those of conventional plastics on marine organism fertilization and biological accumulation, emphasizing the need to revise both the production and marketing of "biodegradable" and "compostable" plastics in order to prevent a further negative impact on ecosystems due to the mismanagement of bioplastic products.

Biodegradable carboxymethyl cellulose based material for sustainable packaging application

The main goal of the present work was to develop a value-added product of biodegradable material for sustainable packaging. The use of agriculture waste-derived carboxymethyl cellulose (CMC) mainly is to reduce the cost involved in the development of the film, at present commercially available CMS is costly. The main focus of the research is to translate the agricultural waste-derived CMC to useful biodegradable polymer suitable for packaging material. During this process CMC was extracted from the agricultural waste mainly sugar cane bagasse and the blends were prepared using CMC (waste derived), gelatin, agar and varied concentrations of glycerol; 1.5% (sample A), 2% (sample B), and 2.5% (sample C) was added. Thus, the film derived from the sample C (gelatin + CMC + agar) with 2.0% glycerol as a plasticizer exhibited excellent properties than other samples A and B. The physiochemical properties of each developed biodegradable plastics (sample A, B, C) were characterized using Fourier Transform Infra-Red (FTIR) spectroscopy and Differential Scanning Calorimetry (DSC), Thermogravimetric analysis (TGA). The swelling test, solubility in different solvents, oil permeability coefficient, water permeability (WP), mechanical strength of the produced material was claimed to be a good material for packaging and meanwhile its biodegradability (soil burial method) indicated their environmental compatibility nature and commercial properties. The reflected work is a novel approach, and which is vital in the conversion of organic waste to value-added product development. There is also another way to utilize commercial CMC in preparation of polymeric blends for the packaging material, which can save considerable time involved in the recovery of CMC from sugarcane bagasse.

Plastics in surface water of southern coastal belt of Sri Lanka (Northern Indian Ocean): Distribution and characterization by FTIR

This study focused on investigating the occurrence, quantification, and the spatial and temporal distribution of plastics in coastal surface water from 12 coastal regions in southern part of Sri Lanka. The overall average densities of macroplastics and mesoplastics were recorded as 0.23 and 0.33 items/m³, respectively. Sampling locations had no significant difference (p > 0.05) on total microplastics (MPs) density (overall mean MPs density: 17.45 ± 3.35 items/m³). MPs debris of less than 1 mm size consisted of >45% of the total number of MPs, whereas the maximum size of microscopically observed plastic debris was 11.04 mm, a filament. Filaments were the most common MPs followed by films. Relatively, blue-colored MPs were highly abundant in this coastal line. The type of MPs was further confirmed by Fourier-Transform Infrared (FTIR) method. Potential plastic pollution factors are hydrodynamics and man-made activities like unsustainable harbor operations, fisheries, and tourism. More attention is needed to reduce plastic pollution regionally.

Adsorption behavior of the antibiotic levofloxacin on microplastics in the presence of different heavy metals in an aqueous solution

In recent years, the composite pollution of microplastics with organic pollutants and heavy metal ions in the water environment, including their combined toxicity, has received increasing attention. However, the mechanism underlying the joint effect of antibiotics and heavy metals on the surface behavior of microplastics has not been reported. The primary purpose of this article was to analyze the adsorption of levofloxacin (OFL) onto polyvinyl chloride (PVC) in an aqueous solution. The adsorption behavior was studied using kinetics, thermodynamics, and isotherm models, and the effects of several environmental factors, such as ionic strength, fulvic acid, and heavy metals, were determined. The adsorption kinetics and isotherms models indicated that the whole adsorption process was controlled by both intraparticle and outer diffusion, as well as chemical adsorption, which was the dominant mechanism. Based on the results of the thermodynamic experiment, the adsorption process was a nonspontaneous and exothermic reaction process. Furthermore, the presence of Cu²⁺, Zn²⁺, and Cr³⁺ ions significantly promoted the adsorption of OFL, but the presence of Cd²⁺ and Pb²⁺ ions inhibited its adsorption. At the same time, the presence of the ionic strength and fulvic acid remarkably restricted the adsorption process. These findings confirmed that electrostatic interactions, ion exchange, intermolecular hydrogen bonds, and halogen bond cooperation were the main adsorption mechanisms. This paper mainly discusses the interaction between combinations of pollutants with microplastics, which provides theoretical guidance for the interface behavior, migration and transformation of marine microplastics in the actual environment.

A review of the treatment options for marine plastic waste in South Africa

Marine plastic is a major worldwide challenge, for which many solutions are being proposed. However, most of the solutions focus on the prevention and collection of the plastic, with little emphasis on the development of waste treatment options. This review seeks to propose areas where further studies could assist to close gaps in knowledge. Some identified gaps include a poor understanding of the quantities and composition of marine plastics, a lack of information about existing marine plastic treatment technologies, and the environmental impact of the available options. To better understand the capabilities of the current South African plastics recycling industry, data from the South African Waste Information Centre (SAWIC) are reported and discussed. While there is a lack of technology development for the treatment of marine plastic globally, the intention of this review is to drive research in this area by creating awareness and encouraging implementation of possible treatment technologies.

Enzymatic Remediation of Polyethylene Terephthalate (PET)-Based Polymers for Effective Management of Plastic Wastes: An Overview

Globally, plastic-based pollution is now recognized as one of the serious threats to the environment. Among different plastics, polyethylene terephthalate (PET) occupies a pivotal place, its excess presence as a waste is a major environmental concern. Mechanical, thermal, and chemical-based treatments are generally used to manage PET pollution. However, these methods are usually expensive or generate secondary pollutants. Hence, there is a need for a cost-effective and environment-friendly method for efficient management of PET-based plastic wastes. Considering this, enzymatic treatment or recycling is one of the important methods to curb PET pollution. In this regard, PET hydrolases have been explored for the treatment of PET wastes. These enzymes act on PET and end its breakdown into monomeric units and subsequently results in loss of weight. However, various factors, specifically PET crystallinity, temperature, and pH, are known to affect this enzymatic process. For effective hydrolysis of PET, high temperature is required, which facilitates easy accessibility of substrate (PET) to enzymes. However, to function at this high temperature, there is a requirement of thermostable enzymes. The thermostability could be enhanced using glycosylation, immobilization, and enzyme engineering. Furthermore, the use of surfactants, additives such as Ca²⁺, Mg²⁺, and hydrophobins (cysteine-rich proteins), has also been reported to enhance the enzymatic PET hydrolysis through facilitating easy accessibility of PET polymers. The present review encompasses a brief overview of the use of enzymes toward the management of PET wastes. Various methods affecting the treatment process and different constraints arising thereof are also systematically highlighted in the review.

Towards control strategies for microplastics in urban water

Microplastics (plastic particles < 5 mm) is a pollution of growing concern. Microplastic pollution is a complex issue that requires systematic attempts to provide an overview and avoid management solutions that have marginal effects or only move the pollution problem. Substance flow analysis (SFA) has been proposed as a useful tool to receive such an overview and has been put forward as valuable for substance management. However, as the research on microplastics has only emerged recently, detailed and reliable SFAs are difficult to perform. In this study, we use three SFA studies for three pollutants (cadmium, copper and pharmaceuticals) to compare flows and strategies to control the flows. This in order to seek guidance for microplastic management and evaluate potential strategies for controlling microplastics. The analysis shows that there has been rigorous control on different levels to abate pollution from cadmium, copper and pharmaceuticals, but where in the system the major control measures have been carried out differ. For microplastics, there are many potential solutions, both in terms of preventive actions and treatment depending on the type of source. When forming management plans for microplastics, the responsibility for each measure and the impact on the whole urban system should be taken into consideration as well as which receiving compartments are particularly valuable and should be avoided.