Plastisphere in freshwaters: An emerging concern

Plastisphere, an ecosystem of microbes thriving on floating plastic debris, has been extensively studied in marine waters since 2013. Currently, very little is known about the freshwater plastisphere. This review seeks to provide a broad insight into the freshwater science of plastisphere in the light of marine plastisphere, including research gaps, suggestions, and rising concerns, which would be of interest to the public, policymakers, and stakeholders. Given that freshwaters are endangered ecosystems, it is imperative to understand the role and impact of plastisphere on freshwaters. Plastic debris, especially microplastics (size <5 mm) in freshwater ecosystems, provide a stable, persistent, and buoyant substrate for microbes. Although current evidence suggests that freshwater environmental conditions and microplastics' physical and chemical properties significantly influence microbial colonisation, its role and integration in the aquatic ecosystems are unknown. Considering that the plastisphere biodiversity is unique, we seek to establish why and how many species co-exist in the plastisphere. Evaluating such fundamental questions should advance our basic understanding of the resilience of plastisphere to the changing environment. Plastisphere microbes, including the pathogenic bacteria, were found in both systems demonstrating their ability to survive on the plastic fragments from one ecosystem to another. A significant concern regarding plastisphere is the potential freshwater dispersal of anthropogenic pollutants and invasive or pathogenic species. Notably, microplastics aggregates may serve as a food source for grazers, which opens the question of the extent to which it can impact freshwater food webs. To gain a thorough understanding of the interplay between microplastics and the biogeochemical cycle, further insight into plastisphere microbes' functional role is needed. This would shed light on the unconsidered freshwater elemental cycling pathways. Given the complexity and universal nature of the plastisphere, strong interdisciplinary global research initiatives or networks are required to address the emerging concerns of plastisphere in freshwaters.

Flotation separation of poly (ethylene terephthalate and vinyl chloride) mixtures based on clean corona modification: Optimization using response surface methodology

Postconsumer polyethylene terephthalate (PET) has potential applications in many areas of manufacturing, but contamination by hazardous polyvinyl chloride (PVC) in common waste streams can reduce its recyclable value. Separating collected PET-PVC mixtures before recycling remains very challenging because of the similar physicochemical properties of PET and PVC. Herein, we describe a novel flotation process with corona modification pretreatment to facilitate the separation of PET-PVC mixtures. Through water contact angle, surface free energy, X-ray photoelectron and FT-IR characterization, we found that polar hydroxyl groups can be more easily introduced on the PVC surface than on the PET surface induced by corona modification. This selective wetting can suppress the floatability of PVC, leading to the separation of PET as floating product. A reliable mechanism including two different hydrogen-abstraction pathways was established. Response surface methodology consisting of Plackett-Burman and Box-Behnken designs was adopted for optimization of the combined process, and control parameters were solved based on high-quality prediction models, with fitting from significant variables and interactions. For physical or chemical circulation strategies with PET purity prioritization, the validated purity of the product reached 96.05% at a 626 W corona power, 5.42 m/min passing speed, 24.78 mg/L frother concentration and 286 L/h air flow rate. For the energy recuperation strategy with PET recovery prioritization, the factual recovery reached 98.08% under a 601 W corona power, 6.04 m/min passing speed, 27.55 mg/L frother concentration and 184 L/h air flow rate. The current work provides technological insights into the cleaner disposal of waste plastics.

Global meta-analysis of microplastic contamination in reservoirs with a novel framework

Microplastic contamination in reservoirs is receiving increasing attention worldwide. However, a holistic understanding of the occurrence, drivers, and potential risks of microplastics in reservoirs is lacking. Building on a systematic review and meta-analysis of 30 existing publications, we construct a global microplastic dataset consisting of 440 collected samples from 43 reservoirs worldwide which we analyze through a framework of Data processing and Multivariate statistics (DM). The purpose is to provide comprehensive understanding of the drivers and mechanisms of microplastic pollution in reservoirs considering three different aspects: geographical distribution, driving forces, and ecological risks. We found that microplastic abundance varied greatly in reservoirs ranging over 2-6 orders of magnitude. Small-sized microplastics (< 1 mm) accounted for more than 60% of the total microplastics found in reservoirs worldwide. The most frequently detected colors, shapes, and polymer types were transparent, fibers, and polypropylene (polyester within aquatic organisms), respectively. Geographic location, seasonal variation and land-use type were main factors influencing microplastic abundance. Detection was also dependent on analytical methods, demonstrating the need for reliable and standardized methods. Interaction of these factors enhanced effects on microplastic distribution. Microplastics morphological characteristics and their main drivers differed between environmental media (water and sediment) and were more diverse in waters compared to sediments. Similarity in microplastic morphologies decreased with increasing geographic distance within the same media. In terms of risks, microplastic pollution and potential ecological risk levels are high in reservoirs and current policies to mitigate microplastic pollution are insufficient. Based on the DM framework, we identified temperate/subtropical reservoirs in Asia as potential high-risk areas and offer recommendations for analytical methods to detect microplastics in waters and sediments. This framework can be extended and applied to other multi-scale and multi-attribute contaminants, providing effective theoretical guidance for reservoir ecosystems pollution control and management.

Assessment of Petroleum-Based Plastic and Bioplastics Degradation Using Anaerobic Digestion

Bioplastics have emerged as a viable alternative to traditional petroleum-based plastic (PET). Three of the most common bioplastic polymers are polyhydroxybutyrate-valerate (PHBV), polylactide (PLA), and cellulose-based bioplastic (CBB). This study assessed biodegradation through anaerobic digestion (AD) of these three bioplastics and PET digested with food waste (FW) at mesophilic (35 °C) and thermophilic (55 °C) temperatures. The four plastic types were digested with FW in triplicate batch reactors. Additionally, two blank treatments (inoculum-only) and two PHBV treatments (with FW + inoculum and inoculum-only) were digested at 35 and 55 °C. The PHBV treatment without FW at 35 °C (PHBV-35) produced the most methane (CH4) normalized by the volatile solids (VS) of the bioplastics over the 104-day experimental period (271 mL CH4/g VS). Most bioplastics had more CH4 production than PET when normalized by digester volume or gram substrate added, with the PLA-FW-55 (5.80 m3 CH4/m3), PHBV-FW-55 (2.29 m3 CH4/m3), and PHBV-55 (4.05 m3 CH4/m3) having 848,275 and 561%, respectively, more CH4 production than the PET treatment. The scanning electron microscopy (SEM) showed full degradation of PHBV pellets after AD. The results show that when PHBV is used as bioplastic, it can be degraded with energy production through AD.

Textile Waste Fiber Regeneration via a Green Chemistry Approach: A Molecular Strategy for Sustainable Fashion

Fast fashion, as a continuously growing part of the textile industry, is widely criticized for its excessive resource use and high generation of textiles. To reduce its environmental impacts, numerous efforts are focused on finding sustainable and eco-friendly approaches to textile recycling. However, waste textiles and fibers are still mainly disposed of in landfills or by incineration after their service life and thereby pollute the natural environment, as there is still no effective strategy to separate natural fibers from chemical fibers. Herein, a green chemistry strategy is developed for the separation and regeneration of waste textiles at the molecular level. Cellulose/wool keratin composite fibers and multicomponent fibers are regenerated from waste textiles via a green chemical process. The strategy attempts to reduce the large amount of waste textiles generated by the fast-developing fashion industry and provide a new source of fibers, which can also address the fossil fuel reserve shortages caused by chemical fiber industries and global food shortages caused by natural fiber production.

Sustainable Bioplastic Made from Biomass DNA and Ionomers

Plastics play important roles in modern life and currently the development of plastic recycling is highly demanding and challenging. To relieve this dilemma, one option is to develop new sustainable bioplastics that are compatible with the environment over the whole material life cycle. We report a sustainable bioplastic made from natural DNA and biomass-derived ionomers, termed as DNA plastics. The sustainability involves all aspects of the production, use, and end-of-life options of DNA plastics: (1) the raw materials are derived from biorenewable resources; (2) the water-processable strategy is environmentally friendly, not involving high-energy consumption, the use of organic solvents, and the production of byproducts; (3) recyclable and nondestructive use is achieved to significantly prolong the service lifetime of the plastics; and (4) the disposal of waste plastics follows two green routes including the recycling of waste plastics and enzyme-triggered controllable degradation under mild conditions. Besides, DNA plastics can be "aqua-welded" to form arbitrary designed products such as a plastic cup. This work provides a solution to transform biobased hydrogel to bioplastic and demonstrates the closed-loop recycling of DNA plastics, which will advance the development of sustainable materials.

Pinene-Based Oxidative Synthetic Toolbox for Scalable Polyester Synthesis

Generation of renewable polymers is a long-standing goal toward reaching a more sustainable society, but building blocks in biomass can be incompatible with desired polymerization type, hampering the full implementation potential of biomaterials. Herein, we show how conceptually simple oxidative transformations can be used to unlock the inherent reactivity of terpene synthons in generating polyesters by two different mechanisms starting from the same α-pinene substrate. In the first pathway, α-pinene was oxidized into the bicyclic verbanone-based lactone and subsequently polymerized into star-shaped polymers via ring-opening polymerization, resulting in a biobased semicrystalline polyester with tunable glass transition and melting temperatures. In a second pathway, polyesters were synthesized via polycondensation, utilizing the diol 1-(1'-hydroxyethyl)-3-(2'-hydroxy-ethyl)-2,2-dimethylcyclobutane (HHDC) synthesized by oxidative cleavage of the double bond of α-pinene, together with unsaturated biobased diesters such as dimethyl maleate (DMM) and dimethyl itaconate (DMI). The resulting families of terpene-based polyesters were thereafter successfully cross-linked by either transetherification, utilizing the terminal hydroxyl groups of the synthesized verbanone-based materials, or by UV irradiation, utilizing the unsaturation provided by the DMM or DMI moieties within the HHDC-based copolymers. This work highlights the potential to apply an oxidative toolbox to valorize inert terpene metabolites enabling generation of biosourced polyesters and coatings thereof by complementary mechanisms.

Towards a predictive model for polymer solubility using the noncovalent interaction index: polyethylene as a case study

In this work we present the development of a novel, quantitative solubility descriptor based on the non-covalent interaction index. It is presented as a more insightful alternative to Hansen's solubility parameters and the COSMO model to assess and predict polymer solubility in different solvents. To this end, we studied the solvation behaviour as a function of the chain length of a single chain of arguably the most simple polymer, polyethylene, in anisole (solvent) and methanol (poor solvent) via molecular dynamics simulations. It was found that in anisole the solute maximized its interface with the solvent, whereas in methanol the macromolecule formed rod-like structures by folding on itself once the chain length surpassed a certain barrier. We assessed this behaviour - which can be related to solubility - quantitatively and qualitatively via well-known descriptors, namely the solvation free energy, and the solvent accessible surface area. In addition, we propose the non-covalent interaction (NCI) index as a versatile descriptor, providing information on the strength, as well as the nature, of the solute-solvent interactions, the solute's intramolecular interactions and on the solute's conformation, both qualitatively and quantitatively. Finally, as a quantitative measure for solubility, defined in this context as the solute's tendency to maximize its interactions with the solvent, we propose two new NCI-based descriptors: the relative integrated NCI density and the integrated NCI difference. The former represents the quantitative difference in solute-solvent interactions between a fully extended coil and the actual conformation during simulation and the latter the quantitative difference between the intermolecular (solute-solvent) and the intramolecular (in the solute) non-covalent interactions. The easy interpretation and calculation of these novel quantities open up the possibility of fast, reliable and insightful high-throughput screening of different (anti)solvent and solute combinations.

Plant Cellulose Nanofiber-Derived Structural Material with High-Density Reversible Interaction Networks for Plastic Substitute

Ubiquitous petrochemical-based plastics pose a potential threat to ecosystems. In response, bioderived and degradable polymeric materials are being developed, but their mechanical and thermal properties cannot compete with those of existing petrochemical-based plastics, especially those used as structural materials. Herein, we report a biodegradable plant cellulose nanofiber (CNF)-derived polymeric structural material with high-density reversible interaction networks between nanofibers, exhibiting mechanical and thermal properties better than those of existing petrochemical-based plastics. This all-green material has substantially improved flexural strength (∼300 MPa) and modulus (∼16 GPa) compared with those of existing petrochemical-based plastics. Its average thermal expansion coefficient is only 7 × 10^-6 K^-1, which is more than 10 times lower than those of petrochemical-based plastics, indicating its dimension is almost unchanged when heated, and thus, it has a thermal dimensional stability that is better than those of plastics. As a fully bioderived and degradable material, the all-green material offers a more sustainable high-performance alternative to petrochemical-based plastics.

A Naturally Derived Nanocomposite Film with Photodynamic Antibacterial Activity: New Prospect for Sustainable Food Packaging

Food packaging with efficient antibacterial ability is highly desirable and challenging in facing the crisis of microbial contamination. However, most present packaging is based on metal-based antibacterial agents and requires a time-consuming antibacterial process. Here, the unique packaging (CC/BB films) featuring aggregation-induced emission behavior and photodynamic inactivation activity is prepared by dispersing self-assembled berberine-baicalin nanoparticles (BB NPs) into a mixed matrix of sodium carboxymethylcellulose-carrageenan (CC). The superiority of this design is that this packaging film can utilize sunlight to generate reactive oxygen species, thus eradicating more than 99% of E. coli and S. aureus within 60 min. Also, this film can release BB NPs to inactivate bacteria under all weather conditions. Surprisingly, the CC/BB nanocomposite film presented excellent mechanical performances (29.80 MPa and 38.65%), hydrophobicity (117.8°), and thermostability. The nanocomposite film is validated to be biocompatible and effective in protecting chicken samples, so this work will provide novel insights to explore safe and efficient antibacterial food packaging.

Temporal Archive of Atmospheric Microplastic Deposition Presented in Ombrotrophic Peat

Ombrotrophic peatland-fed solely from atmospheric deposition of nutrients and precipitation-provide unique archives of atmospheric pollution and have been used to illustrate trends and changes in atmospheric trace element composition from the recent decadal to the Holocene period. With the acknowledgment of atmosphere plastic pollution, analysis of ombrotrophic peat presents an opportunity to characterize the historical atmospheric microplastic pollution prevalence. Ombrotrophic peatland is often located in comparatively pristine mountainous and boreal areas, acting as sentinels of environmental change. In this paired site study, a Sphagnum ombrotrophic peat record is used for the first time to identify the trend of atmospheric microplastic pollution. This high altitude, remote location ombrotrophic peat archive pilot study identifies microplastic presence in the atmospheric pollution record, increasing from <5(±1) particles/m²/day in the 1960s to 178(±72) particles/m²/day in 2015-2020 in a trend similar to the European plastic production and waste management. Compared to this catchment's lake sediment archive, the ombrotrophic peat core appears to be effective in collecting and representing atmospheric microplastic deposition in this remote catchment, collecting microplastic particles that are predominantly ≤20 μm. This study suggests that peat records may be a useful tool in assessing the past quantities and trends of atmospheric microplastic.

Uptake and Accumulation of Nano/Microplastics in Plants: A Critical Review

The ubiquitous presence of microplastics (MPs) and nanoplastics (NPs) in the environment is an undeniable and serious concern due to their higher persistence and extensive use in agricultural production. This review highlights the sources and fate of MPs and NPs in soil and their uptake, translocation, and physiological effects in the plant system. We provide the current snapshot of the latest reported studies with the majority of literature spanning the last five years. We draw attention to the potential risk of MPs and NPs in modern agriculture and their effects on plant growth and development. We also highlight their uptake and transport pathways in roots and leaves via different exposure methods in plants. Conclusively, agricultural practices, climate changes (wet weather and heavy rainfall), and soil organisms play a major role in transporting MPs and NPs in soil. NPs are more prone to enter plant cell walls as compared to MPs. Furthermore, transpiration pull is the dominant factor in the plant uptake and translocation of plastic particles. MPs have negligible negative effects on plant physiological and biochemical indicators. Overall, there is a dire need to establish long-term studies for a better understanding of their fate and associated risks mechanisms in realistic environment scenarios for safe agricultural functions.

The effectiveness of legislative and voluntary strategies to prevent ocean plastic pollution: Lessons from the UK and South Pacific

The islands of the South Pacific contribute a fraction of the mis-managed plastics in the world's ocean, yet the region is one of the main recipients of its impacts. Based on expert interviews and a review of current strategies to prevent marine plastic pollution in six countries (Australia, New Zealand, Fiji, Tonga, Vanuatu, United Kingdom), this paper identifies several interventions - legislative, financial, voluntary - which governments, organisations and individuals can learn from. Both voluntary and statutory consumer-based behaviour change campaigns are well developed and somewhat successful in several countries. While sub-national policies do not inhibit progress, they are not optimal. Harmonisation across the territories of federal and devolved systems is beneficial, such as container return schemes, levies, and bans. Vanuatu has displayed high ambition, and the challenges in achieving this serve as a case study. A coordinated global strategy with associated legislation aimed at tackling plastic pollution is critical.

Plastic-Degrading Potential across the Global Microbiome Correlates with Recent Pollution Trends

Biodegradation is a plausible route toward sustainable management of the millions of tons of plastic waste that have accumulated in terrestrial and marine environments. However, the global diversity of plastic-degrading enzymes remains poorly understood. Taking advantage of global environmental DNA sampling projects, here we constructed hidden Markov models from experimentally verified enzymes and mined ocean and soil metagenomes to assess the global potential of microorganisms to degrade plastics. By controlling for false positives using gut microbiome data, we compiled a catalogue of over 30,000 nonredundant enzyme homologues with the potential to degrade 10 different plastic types. While differences between the ocean and soil microbiomes likely reflect the base compositions of these environments, we find that ocean enzyme abundance increases with depth as a response to plastic pollution and not merely taxonomic composition. By obtaining further pollution measurements, we observed that the abundance of the uncovered enzymes in both ocean and soil habitats significantly correlates with marine and country-specific plastic pollution trends. Our study thus uncovers the earth microbiome's potential to degrade plastics, providing evidence of a measurable effect of plastic pollution on the global microbial ecology as well as a useful resource for further applied research. IMPORTANCE Utilization of synthetic biology approaches to enhance current plastic degradation processes is of crucial importance, as natural plastic degradation processes are very slow. For instance, the predicted lifetime of a polyethylene terephthalate (PET) bottle under ambient conditions ranges from 16 to 48 years. Moreover, although there is still unexplored diversity in microbial communities, synergistic degradation of plastics by microorganisms holds great potential to revolutionize the management of global plastic waste. To this end, the methods and data on novel plastic-degrading enzymes presented here can help researchers by (i) providing further information about the taxonomic diversity of such enzymes as well as understanding of the mechanisms and steps involved in the biological breakdown of plastics, (ii) pointing toward the areas with increased availability of novel enzymes, and (iii) giving a basis for further application in industrial plastic waste biodegradation. Importantly, our findings provide evidence of a measurable effect of plastic pollution on the global microbial ecology.

Informing the Public and Educating Students on Plastic Recycling

Approximately 300 million tons of plastic waste is generated per year. The major portion of this plastic waste is landfilled, while part of it leaks into the environment. When plastic waste enters the terrestrial or aqueous environment, it can have negative impacts on ecosystems, human health, and wildlife. Increasing the amount of plastic waste that is recycled will correspondingly reduce the amount of plastic waste that enters the environment. By educating the public and industry on plastic recycling, current recycling programs can be used more efficiently, and new programs can be created. Education material on plastic recycling is available through professional and industry associations, foundations with an environmental focus, university courses, and short courses offered with private companies. This review assembles and analyzes the current education material on plastic recycling that is available from these providers. The material compiled here can be used to gain insight into specific plastic recycling-related topics, to identify areas of recycling education that can be improved, and as a resource to help build university level courses. There is currently a dearth of plastic recycling courses offered at the university level. Educating more students on plastic recycling will equip them with the knowledge and skills to make informed decisions as consumers, and to implement plastic recycling systems at the professional level.

Towards more ecologically relevant investigations of the impacts of microplastic pollution in freshwater ecosystems

Microplastic pollution is a major environmental concern and the subject of a rapidly growing body of research. Much of this research has focused on the direct effects of microplastics on single species and there is limited information on how microplastics affect different functional groups of organisms, multi-species interactions, and ecosystem processes. We focused on freshwater systems and reviewed 146 studies of microplastic effects on freshwater biota and recorded features including particle characteristics, study designs, functional types of species tested and ecotoxicological endpoints measured. Study species were categorized based on their ecosystem role/functional feeding group rather than taxonomy. We found that most studies were conducted on single species (95%) and focused on a narrow range of functional groups of organisms (mostly filter feeders, 37% of studies). Very few studies have investigated multi-species interactions and ecosystem processes. In many studies, certain characteristics of microplastics, such as polymer type were not well matched with the feeding and habitat ecology of test species, potentially reducing their ecological relevance. Median laboratory study test concentrations were 5-6 orders of magnitude higher than those reported in the field and few studies considered the effects of chemical additives in plastics (6%). We recommend that studies addressing the ecological effects of microplastics need to address neglected functional groups of organisms, design experiments to better match the ecology of test species, and increase in experimental scale and complexity to identify any indirect effects on species interactions and ecosystem processes. We suggest that examining microplastics through an ecological lens that better integrates the feeding and habitat ecology of test organisms will advance our understanding of the effects microplastics have in the environment.

Green Recycling Process for Polyurethane Foams by a Chem-Biotech Approach

Polyurethanes (PUs) are highly resistant materials used for building insulation or automotive seats. The polyurethane end-of-life issue must be addressed by the development of efficient recycling techniques. Since conventional recycling processes are not suitable for thermosets, waste management of PU foam is particularly questioning. By coupling biological and chemical processes, this study aimed at developing a green recycling pathway for PU foam using enzymes for depolymerization. For instance, enzymatic degradation of a PU foam synthesized with polycaprolactone and toluene diisocyanate led to a weight loss of 25 % after 24 h of incubation. The corresponding degradation products were recovered and identified as 6-hydroxycaproic acid and a short acid-terminated diurethane. An organometallic-catalyzed synthesis of second-generation polymers from these building blocks was carried out. A polymer with a high average molar mass of 74000 (M_w ) was obtained by mixing 50 % of recycled building blocks and 50 % of neat 6-hydroxycaproic acid. A poly(ester urethane) was synthesized without the use of toxic and decried polyisocyanates. It is the first time that a study offers the vision of a recycling loop starting from PU wastes and finishing with a second-generation polymer in a full circular approach.

Synthetic Lubricants Derived from Plastic Waste and their Tribological Performance

The energy efficiency, mechanical durability, and environmental compatibility of all moving machine components rely heavily on advanced lubricants for smooth and safe operation. Herein an alternative family of high-quality liquid (HQL) lubricants was derived by the catalytic conversion of pre- and post-consumer polyolefin waste. The plastic-derived lubricants performed comparably to synthetic base oils such as polyalphaolefins (PAOs), both with a wear scar volume (WSV) of 7.5×10^-5  mm^-3 . HQLs also performed superior to petroleum-based lubricants such as Group III mineral oil with a WSV of 1.7×10^-4  mm^-3 , showcasing a 44 % reduction in wear. Furthermore, a synergistic reduction in friction and wear was observed when combining the upcycled plastic lubricant with synthetic oils. Life cycle and techno-economic analyses also showed this process to be energetically efficient and economically feasible. This novel technology offers a cost-effective opportunity to reduce the harmful environmental impact of plastic waste on our planet and to save energy through reduction of friction and wear-related degradations in transportation applications akin to synthetic oils.

Jacques L, Bornscheuer UT, Syrén P. Biocatalysis in the Recycling Landscape for Synthetic Polymers and Plastics towards Circular Textiles

Although recovery of fibers from used textiles with retained material quality is desired, separation of individual components from polymer blends used in today's complex textile materials is currently not available at viable scale. Biotechnology could provide a solution to this pressing problem by enabling selective depolymerization of recyclable fibers of natural and synthetic origin, to isolate constituents or even recover monomers. We compiled experimental data for biocatalytic polymer degradation with a focus on synthetic polymers with hydrolysable links and calculated conversion rates to explore this path The analysis emphasizes that we urgently need major research efforts: beyond cellulose-based fibers, biotechnological-assisted depolymerization of plastics so far only works for polyethylene terephthalate, with degradation of a few other relevant synthetic polymer chains being reported. In contrast, by analyzing market data and emerging trends for synthetic fibers in the textile industry, in combination with numbers from used garment collection and sorting plants, it was shown that the use of difficult-to-recycle blended materials is rapidly growing. If the lack of recycling technology and production trend for fiber blends remains, a volume of more than 3400 Mt of waste will have been accumulated by 2030. This work highlights the urgent need to transform the textile industry from a biocatalytic perspective.

Plastic contamination of a Galapagos Island (Ecuador) and the relative risks to native marine species

Ecuador's Galapagos Islands and their unique biodiversity are a global conservation priority. We explored the presence, composition and environmental drivers of plastic contamination across the marine ecosystem at an island scale, investigated uptake in marine invertebrates and designed a systematic priority scoring analysis to identify the most vulnerable vertebrate species. Beach contamination varied by site (macroplastic 0-0.66 items·m^-2, microplastics 0-448.8 particles·m^-2 or 0-74.6 particles·kg^-1), with high plastic accumulation on east-facing beaches that are influenced by the Humboldt Current. Local littering and waste management leakages accounted for just 2% of macroplastic. Microplastics (including anthropogenic cellulosics) were ubiquitous but in low concentrations in benthic sediments (6.7-86.7 particles·kg^-1) and surface seawater (0.04-0.89 particles·m^-3), with elevated concentrations in the harbour suggesting some local input. Microplastics were present in all seven marine invertebrate species examined, found in 52% of individuals (n = 123) confirming uptake of microplastics in the Galapagos marine food web. Priority scoring analysis combining species distribution information, IUCN Red List conservation status and literature evidence of harm from entanglement and ingestion of plastics in similar species identified 27 marine vertebrates in need of urgent, targeted monitoring and mitigation including pinnipeds, seabirds, turtles and sharks.

The role of plastic debris in the biogeochemical cycle of mercury in Lake Erie and San Francisco Bay

The accumulation of plastic debris that concentrates hydrophobic compounds and microbial communities creates the potential for altered aquatic biogeochemical cycles. This study investigated the role of plastic debris in the biogeochemical cycling of mercury in surface waters of the San Francisco Bay, Sacramento River, Lake Erie, and in coastal seawater. Total mercury and monomethylmercury were measured on plastic debris from all study sites. Plastic-bound microbial communities from Lake Erie and San Francisco Bay contained several lineages of known mercury methylating microbes, however the hgcAB gene cluster was not detected using polymerase chain reaction. These plastic-bound microbial communities also contained species that possess the mer operon, and merA genes were detected using polymerase chain reaction. In coastal seawater incubations, rapid mercury methylation percentages were greater in the presence of microplastics and demethylation percentages decreased as monomethylmercury additions adsorbed to microplastics. These findings suggest that plastic pollution has the potential to alter the biogeochemical cycling of mercury in aquatic ecosystems.

Achieving net-zero greenhouse gas emission plastics by a circular carbon economy

[Figure: see text].

The nine development bands: A conceptual framework and global theory for waste and development

Solid waste management (SWM) is an essential utility service. More than two to three billion people worldwide still lack basic services, whereas some countries are already moving beyond SWM towards waste and resource management (WaRM) and a circular economy. This paper sets out a novel conceptual framework and global theory of waste and development, providing a road map, allowing a country or city to locate their current position and plot their way ahead. We identify nine development bands (9DBs) with significant commonalities in terms of critical challenges and developmental pressure points. DB1-DB4 reflect stepwise improvement towards the new baseline of meeting the SDG 11.6.1 indicators of universal collection and management in controlled facilities (DB5). Countries can then choose to move towards environmentally sound management and the 'reduce, reuse, recycle' (3Rs) (DB6-9), with an ultimate aspiration of 'zero waste'. We test the 9DBs conceptual framework against historical journeys of higher income countries. The main application will be in low- and middle-income countries striving towards SDG 11.6.1, where it fills a key gap in the practitioners' toolkit by enabling initial framing/scoping of the problem and smarter interventions to be designed and sense checked. Key insights include targeted governance/institutional reforms, appropriate and affordable systems/technology and adapting solutions to a diversity of local needs and realities.

Challenges and Opportunities for Recycled Polyethylene Fishing Nets: Towards a Circular Economy

Plastic waste generation has become an important problem that critically affects marine and oceans environments. Fishing nets gear usually have a relatively short lifespan, and are abandoned, discarded and lost, what makes them one of the largest generators of ocean plastic waste. Recycled polyolefin resins from fishing nets (rFN), especially from polyethylene (PE), have poor properties due to the presence of contaminants and/or excessive degradation after its lifetime. These reasons limit the use of these recycled resins. This work aims to study the incorporation of recycled fishing nets PE-made to different grades of virgin PE, in order to evaluate the potential use of these rFN in the development of new products. The recovered fishing nets have been fully characterized to evaluate its properties after the collection and recycling process. Then, different PE virgin resins have been mechanically blended with the recovered fishing nets at different recycling contents to study its feasibility for fishing nets or packaging applications. Critical mechanical properties for these applications, as the elongation at break, impact strength or environmental stress cracking resistance have been deeply evaluated. Results show important limitations for the manufacture of fibers from recycled PE fishing nets due to the presence of inorganic particles from the marine environment, which restricts the use of rFN for its original application. However, it is proved that a proper selection of PE raw resins, to be used in the blending process, allows other possible applications, such as non-food contact bottles, which open up new ways for using the fishing nets recyclates, in line with the objectives pursued by the Circular Economy of Plastics.

Unextractable fossil fuels in a 1.5 °C world

Parties to the 2015 Paris Agreement pledged to limit global warming to well below 2 °C and to pursue efforts to limit the temperature increase to 1.5 °C relative to pre-industrial times¹. However, fossil fuels continue to dominate the global energy system and a sharp decline in their use must be realized to keep the temperature increase below 1.5 °C (refs. ^2-7). Here we use a global energy systems model⁸ to assess the amount of fossil fuels that would need to be left in the ground, regionally and globally, to allow for a 50 per cent probability of limiting warming to 1.5 °C. By 2050, we find that nearly 60 per cent of oil and fossil methane gas, and 90 per cent of coal must remain unextracted to keep within a 1.5 °C carbon budget. This is a large increase in the unextractable estimates for a 2 °C carbon budget⁹, particularly for oil, for which an additional 25 per cent of reserves must remain unextracted. Furthermore, we estimate that oil and gas production must decline globally by 3 per cent each year until 2050. This implies that most regions must reach peak production now or during the next decade, rendering many operational and planned fossil fuel projects unviable. We probably present an underestimate of the production changes required, because a greater than 50 per cent probability of limiting warming to 1.5 °C requires more carbon to stay in the ground and because of uncertainties around the timely deployment of negative emission technologies at scale.

Plastic waste associated with the COVID-19 pandemic: Crisis or opportunity?

Coronavirus Diseases 2019 (COVID-19) pandemic has a huge impact on the plastic waste management in many countries due to the sudden surge of medical waste which has led to a global waste management crisis. Improper management of plastic waste may lead to various negative impacts on the environment, animals, and human health. However, adopting proper waste management and the right technologies, looking in a different perception of the current crisis would be an opportunity. About 40% of the plastic waste ended up in landfill, 25% incinerated, 16% recycled and the remaining 19% are leaked into the environment. The increase of plastic wastes and demand of plastic markets serve as a good economic indicator for investor and government initiative to invest in technologies that converts plastic waste into value-added product such as fuel and construction materials. This will close the loop of the life cycle of plastic waste by achieving a sustainable circular economy. This review paper will provide insight of the state of plastic waste before and during the COVID-19 pandemic. The treatment pathway of plastic waste such as sterilisation technology, incineration, and alternative technologies available in converting plastic waste into value-added product were reviewed.

Microplastics and anthropogenic fibre concentrations in lakes reflect surrounding land use

Pollution from microplastics and anthropogenic fibres threatens lakes, but we know little about what factors predict its accumulation. Lakes may be especially contaminated because of long water retention times and proximity to pollution sources. Here, we surveyed anthropogenic microparticles, i.e., microplastics and anthropogenic fibres, in surface waters of 67 European lakes spanning 30° of latitude and large environmental gradients. By collating data from >2,100 published net tows, we found that microparticle concentrations in our field survey were higher than previously reported in lakes and comparable to rivers and oceans. We then related microparticle concentrations in our field survey to surrounding land use, water chemistry, and plastic emissions to sites estimated from local hydrology, population density, and waste production. Microparticle concentrations in European lakes quadrupled as both estimated mismanaged waste inputs and wastewater treatment loads increased in catchments. Concentrations decreased by 2 and 5 times over the range of surrounding forest cover and potential in-lake biodegradation, respectively. As anthropogenic debris continues to pollute the environment, our data will help contextualise future work, and our models can inform control and remediation efforts.

Intergenerational learning: A recommendation for engaging youth to address marine debris challenges

Youth can impact environmental attitudes and behaviors among adults. Indeed, research on intergenerational learning has demonstrated the influence of young people on adults in their lives for myriad environmental topics. Intergenerational learning (IGL) refers to the bidirectional transfer of knowledge, attitudes, or behaviors from children to their parents or other adults and vice versa. We suggest an educational framework wherein K-12 marine debris education designed to maximize IGL may be a strategy to accelerate interdisciplinary, community-level solutions to marine debris. Although technical strategies continue to be developed to address the marine debris crisis, even the most strictly technical of these benefit from social support. Here, we present 10 Best Practices grounded in educational, IGL, and youth civic engagement literature to promote marine debris solutions. We describe how integrating IGL and civic engagement into K-12-based marine debris curricula may start a virtuous circle benefiting teachers, students, families, communities, and the ocean.

Chemically recyclable thermoplastics from reversible-deactivation polymerization of cyclic acetals

Identifying plastics capable of chemical recycling to monomer (CRM) is the foremost challenge in creating a sustainable circular plastic economy. Polyacetals are promising candidates for CRM but lack useful tensile strengths owing to the low molecular weights produced using current uncontrolled cationic ring-opening polymerization (CROP) methods. Here, we present reversible-deactivation CROP of cyclic acetals using a commercial halomethyl ether initiator and an indium(III) bromide catalyst. Using this method, we synthesize poly(1,3-dioxolane) (PDXL), which demonstrates tensile strength comparable to some commodity polyolefins. Depolymerization of PDXL using strong acid catalysts returns monomer in near-quantitative yield and even proceeds from a commodity plastic waste mixture. Our efficient polymerization method affords a tough thermoplastic that can undergo selective depolymerization to monomer.

Effect of microplastics on organic matter decomposition in paddy soil amended with crop residues and labile C: A three-source-partitioning study

Microplastics (MPs) are a widespread pollutant in terrestrial ecosystems. However, knowledge on how MPs impact soil organic matter (SOM) decomposition and the priming effect (PE) in rice paddy soil remains limited. By employing a three-source-partitioning approach, we investigated the interactive impact of MP dosage (none, low [0.01% w/w] or high [1% w/w]), labile C (¹⁴C-labeled glucose), and ¹³C-labeled rice straw addition on SOM decomposition and PE. Compared to soil without C addition (i.e., control), total SOM-derived CO₂ in low-MP soil declined by 13.2% and 7.1% after straw and glucose addition, respectively. Under combined glucose and rice straw addition, glucose-induced PE was up to 10 times stronger in the presence of low-MPs compared to that in high-MPs. However, glucose induced negative PE on rice straw decomposition in the presence of MPs. SOM decomposition was much higher under low MP dosage than under high MP dosage. However, MPs had a negligible effect on the mineralization of exogenous C substrate (glucose or straw). This study provides a novel and valuable insight on how MPs affect SOM turnover and C sequestration in paddy soil, highlighting the significance of interactions between environmental pollutants and biogeochemical processes that affect CO₂ fluxes.

A sustainable approach to cathode delamination using a green solvent

Designing an environment-friendly delamination process for an end-of-life (EoL) composite cathode is a crucial step in direct cathode recycling. In this study, the green solvent dimethyl isosorbide (DMI) is explored to extract cathode active materials (AMs) from the Al current collector via dissolving the polyvinylidene fluoride (PVDF) binder. Mechanistic insight suggests that binder removal from the Al substrate proceeds via reducing polymer interchain interaction through DMI penetrating into the PVDF crystalline region. Polymer–solvent interaction may increase via establishing hydrogen bond between PVDF and DMI, which facilitates binder removal. Analytical characterizations including ¹H NMR, FTIR, XRD and SEM-EDS reveal that the molecular, micro, and crystal structures of the recovered cathode AMs, PVDF and Al foil are preserved. This finding is expected to provide a replacement for the toxic organic solvent N-methylpyrrolidone (NMP) and offers an effective, ecofriendly, and sustainable direct cathode recycling approach for spent Li-ion batteries.

A green solvent-based methodology was developed for delaminating cathode active materials from aluminium current collectors in end-of-life Li-ion batteries.

Breakthrough in polyurethane bio-recycling: An efficient laccase-mediated system for the degradation of different types of polyurethanes

Development of green, efficient and profitable recycling processes for plastic material will contribute to reduce the expanding plastic pollution and microplastics accumulation in the environment. Polyurethanes (PU) are versatile polymers with a large range of chemical compositions and structures. This variability increases the complexity of PU waste management. Biological recycling researchers have recently demonstrated great interest in polyethylene terephthalate. The adaptation of this route towards producing polyurethanes requires the discovery of enzymes that are able to depolymerize a large variety of PU. A laccase mediated system (LMS) was tested on four representative PU models, with different structures (foams and thermoplastics), and chemical compositions (polyester- and polyether-based PU). Size exclusion chromatography was performed on the thermoplastics and this revealed a significant reduction in the molar masses after 18 days of incubation at 37 °C. Degradation of foams under the same conditions was demonstrated by microscopy and compression assay for both polyester- and polyether-based PU. This study represents a major breakthrough in PU degradation, as it is the first time that enzymatic degradation has been clearly demonstrated on a polyether-based PU foam. This work is a step forward in the development of a sustainable recycling pathway, adapted to a large variety of PU materials.

Marine litter on the seafloors of the Bohai Sea, Yellow Sea and northern East China Sea

Seafloor litter was investigated in the Bohai Sea, Yellow Sea, and northern East China Sea (BYnECS) based on fisheries-independent bottom trawl surveys in 2019. The mean density of seafloor litter was 48.44 items∙km^-2 (44.56 kg∙km^-2) in the BYnECS, which was at an intermediate level compared with the values observed in other continental shelf areas worldwide. There were significant differences in the density of seafloor litter among different regions (P < 0.05), and the high-density litter accumulation areas in the northern Yellow Sea and Changjiang estuary and adjacent waters were close to the sediment accumulation areas. Plastics were predominant in the BYnECS and accounted for 72.80%/44.05% (number/weight) of the seafloor litter. Fishery-related litter was the main source of seafloor litter in the BYnECS. This study systematically reports the density, composition, sources and spatial distribution of seafloor litter in the BYnECS, thereby providing a scientific basis for the management of marine litter.

The Critical Importance of Adopting Whole-of-Life Strategies for Polymers and Plastics

Plastics have been revolutionary in numerous sectors, and many of the positive attributes of modern life can be attributed to their use. However, plastics are often treated only as disposable commodities, which has led to the ever-increasing accumulation of plastic and plastic by-products in the environment as waste, and an unacceptable growth of microplastic and nanoplastic pollution. The catchphrase “plastics are everywhere”, perhaps once seen as extolling the virtues of plastics, is now seen by most as a potential or actual threat. Scientists are confronting this environmental crisis, both by developing recycling methods to deal with the legacy of plastic waste, and by highlighting the need to develop and implement effective whole-of-life strategies in the future use of plastic materials. The importance and topicality of this subject are evidenced by the dramatic increase in the use of terms such as “whole of life”, “life-cycle assessment”, “circular economy” and “sustainable polymers” in the scientific and broader literature. Effective solutions, however, are still to be forthcoming. In this review, we assess the potential for implementing whole-of-life strategies for plastics to achieve our vision of a circular economy. In this context, we consider the ways in which given plastics might be recycled into the same plastic for potential use in the same application, with minimal material loss, the lowest energy cost, and the least potential for polluting the environment.

Temperate UV-Accelerated Weathering Cycle Combined with HT-GPC Analysis and Drop Point Testing for Determining the Environmental Instability of Polyethylene Films

Polyethylene films are one of the most frequently used packaging materials in our society, due to their combination of strength and flexibility. An unintended consequence of this high use has been the ever-increasing accumulation of polyethylene films in the natural environment. Previous attempts to understand their deterioration have either focused on their durability using polymer analysis; or they have focused on changes occurring during outdoor exposure. Herein, this study combines those strategies into one, by studying the chemical and physical changes in the polyethylene structure in a laboratory using molecular weight and IR spectroscopic mapping analysis, combined with temperate UV-accelerated weathering cycles. This approach has been correlated to real-world outdoor exposure timeframes by parallel testing of the sample polyethylene films in Florida and France. The formation of polyethylene microparticles or polyethylene waxes is elucidated through comparison of drop point testing and molecular weight analysis.

Plastic ingestion as an evolutionary trap: Toward a holistic understanding

Human activities are changing our environment. Along with climate change and a widespread loss of biodiversity, plastic pollution now plays a predominant role in altering ecosystems globally. Here, we review the occurrence of plastic ingestion by wildlife through evolutionary and ecological lenses and address the fundamental question of why living organisms ingest plastic. We unify evolutionary, ecological, and cognitive approaches under the evolutionary trap theory and identify three main factors that may drive plastic ingestion: (i) the availability of plastics in the environment, (ii) an individual's acceptance threshold, and (iii) the overlap of cues given by natural foods and plastics.

The global threat from plastic pollution

Plastic pollution accumulating in an area of the environment is considered "poorly reversible" if natural mineralization processes occurring there are slow and engineered remediation solutions are improbable. Should negative outcomes in these areas arise as a consequence of plastic pollution, they will be practically irreversible. Potential impacts from poorly reversible plastic pollution include changes to carbon and nutrient cycles; habitat changes within soils, sediments, and aquatic ecosystems; co-occurring biological impacts on endangered or keystone species; ecotoxicity; and related societal impacts. The rational response to the global threat posed by accumulating and poorly reversible plastic pollution is to rapidly reduce plastic emissions through reductions in consumption of virgin plastic materials, along with internationally coordinated strategies for waste management.

The missing ocean plastic sink: Gone with the rivers

Plastic floating at the ocean surface, estimated at tens to hundreds of thousands of metric tons, represents only a small fraction of the estimated several million metric tons annually discharged by rivers. Such an imbalance promoted the search for a missing plastic sink that could explain the rapid removal of river-sourced plastics from the ocean surface. On the basis of an in-depth statistical reanalysis of updated data on microplastics-a size fraction for which both ocean and river sampling rely on equal techniques-we demonstrate that current river flux assessments are overestimated by two to three orders of magnitude. Accordingly, the average residence time of microplastics at the ocean surface rises from a few days to several years, strongly reducing the theoretical need for a missing sink.

V2O5-WO3/TiO2 Catalyst for Efficient Synergistic Control of NOx and Chlorinated Organics: Insights into the Arsenic Effect

Municipal solid waste incineration and the iron and steel smelting industry can simultaneously discharge NO_x and chlorinated organics, particularly polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs). Synergistic control of these pollutants has been considered among the most cost-effective methods. This work combined experimental and computational methods to investigate the reaction characteristics of a catalytically synergistic approach and gives the first insight into the effect of arsenic (As) on the multipollutant conversion efficiency, synergistic reaction mechanism, and toxic byproduct distribution over a commercial V₂O₅-WO₃/TiO₂ catalyst. The loaded As₂O₃ species were shown to distinctly decrease the formation energy of an oxygen vacancy at the V-O-V site, which likely contributed to the extensive formation of more toxic polychlorinated byproducts in the synergistic reaction. The As₂O₅ species strongly attacked neighboring V═O sites forming the As-O-V bands. Such an interaction deactivated the deNO_x reaction, but led to excessive NO being oxidized into NO₂ that greatly promoted the V⁵⁺-V⁴⁺ redox cycle and in turn facilitated chlorobenzene (CB) oxidation. Subsequent density functional theory (DFT) calculation further reveals that both the As₂O₃ and As₂O₅ loadings can facilitate H₂O adsorption on the V₂O₅-WO₃/TiO₂ catalyst, leading to competitive adsorption between H₂O and CB, and thereby deactivate the CB oxidation with water stream.

Microplastic pollution in Marine Protected Areas of Southern Sri Lanka

Microplastics (MPs) are ubiquitous in marine environment. The prevalence of MPs in coastal and lagoon sediments, and water were studied in two Marine Protected Areas (MPAs); Bundala National Park (BNP) and Hikkaduwa Marine National Park (HNP) in Sri Lanka. Both areas are important for turtles, birds and coral ecosystems, all of which are particularly threatened by MPs. Abundance of MPs was generally higher in both coastal sediments and waters in HNP (111±29 MPs/m² for sediments and 0.515±0.054 MPs/m³ for water) than in the BNP (102±16 MPs/m² for sediments and 0.276±0.077 MPs/m³ for water). The most common shape and polymer type of MPs were fragments and Polyethylene respectively. This research is the first to survey MPs in MPAs in Sri Lanka and provides a baseline of MPs pollution in these environments for future research and management.

Global Plastic Pollution Observation System to Aid Policy

Plastic pollution has become one of the most pressing environmental challenges and has received commensurate widespread attention. Although it is a top priority for policymakers and scientists alike, the knowledge required to guide decisions, implement mitigation actions, and assess their outcomes remains inadequate. We argue that an integrated, global monitoring system for plastic pollution is needed to provide comprehensive, harmonized data for environmental, societal, and economic assessments. The initial focus on marine ecosystems has been expanded here to include atmospheric transport and terrestrial and freshwater ecosystems. An earth-system-level plastic observation system is proposed as a hub for collecting and assessing the scale and impacts of plastic pollution across a wide array of particle sizes and ecosystems including air, land, water, and biota and to monitor progress toward ameliorating this problem. The proposed observation system strives to integrate new information and to identify pollution hotspots (i.e., production facilities, cities, roads, ports, etc.) and expands monitoring from marine environments to encompass all ecosystem types. Eventually, such a system will deliver knowledge to support public policy and corporate contributions to the relevant United Nations (UN) Sustainable Development Goals (SDGs).