A comprehensive assessment of plastic remediation technologies

The global presence of plastic litter and its accumulation in the environment has become an issue of concern to the public and policymakers. This concern has triggered innovators in past decades to design and develop a multitude of remediation technologies to prevent plastic from entering the environment, or to clean up legacy litter. This study aims to (i) systematically review the current scientific literature on plastic remediation technologies, (ii) create a 'plastic clean-up and prevention overview' illustrating 124 remediation technologies and 29 characteristics, (iii) qualitatively analyse their key characteristics (e.g., fields of application, targeted plastic), and (iv) investigate challenges and opportunities of clean-up technologies for inland waterways (e.g., canals, rivers) and ports. We identified 61 scientific publications on plastic remediation technologies, until June 2022. Thirty-four of these studies were published within the last three years, demonstrating a growing interest. The presented overview indicates that inland waterways are, so far, the preferred field of application, with 22 technologies specifically designed for cleaning up plastics from inland waterways, and 52 additional ones with the potential to be installed in these locations. Given the importance of clean-up technologies in inland waterways, we highlighted their strengths, weaknesses, opportunities, and threats (SWOT). Our results indicate that, despite the challenges, these technologies provide essential prospects, from improving the environmental quality to raising awareness. Our study is instrumental as it illustrates an up-to-date overview and provides a comprehensive analysis of current in design phase, testing, and in use plastic remediation technologies.

Association between Microorganisms and Microplastics: How Does It Change the Host-Pathogen Interaction and Subsequent Immune Response?

Plastic pollution is a significant problem worldwide because of the risks it poses to the equilibrium and health of the environment as well as to human beings. Discarded plastic released into the environment can degrade into microplastics (MPs) due to various factors, such as sunlight, seawater flow, and temperature. MP surfaces can act as solid scaffolds for microorganisms, viruses, and various biomolecules (such as LPS, allergens, and antibiotics), depending on the MP characteristics of size/surface area, chemical composition, and surface charge. The immune system has efficient recognition and elimination mechanisms for pathogens, foreign agents, and anomalous molecules, including pattern recognition receptors and phagocytosis. However, associations with MPs can modify the physical, structural, and functional characteristics of microbes and biomolecules, thereby changing their interactions with the host immune system (in particular with innate immune cells) and, most likely, the features of the subsequent innate/inflammatory response. Thus, exploring differences in the immune response to microbial agents that have been modified by interactions with MPs is meaningful in terms of identifying new possible risks to human health posed by anomalous stimulation of immune reactivities.

Discussion about suitable applications for biodegradable plastics regarding their sources, uses and end of life

This opinion paper offers a scientific view on the current debate of the place of biodegradable plastics as part of the solution to deal with the growing plastic pollution in the world's soil, aquatic, and marine compartments. Based on the current scientific literature, we focus on the current limits to prove plastic biodegradability and to assess the toxicity of commercially used biobased and biodegradable plastics in natural environments. We also discuss the relevance of biodegradable plastics for selected applications with respect to their use and end of life. In particular, we underlined that there is no universal biodegradability of plastics in any ecosystem, that considering the environment as a waste treatment system is not acceptable, and that the use of compostable plastics requires adaptation of existing organic waste collection and treatment channels.

Plastic waste reprocessing for circular economy: A systematic scoping review of risks to occupational and public health from legacy substances and extrusion

The global plastics reprocessing sector is likely expand as the circular economy becomes more established and efforts to curb plastic pollution increase. Via a critical systematic scoping review (PRISMA-ScR), we focused on two critical challenges for occupational and public health that will require consideration along with this expansion: (1) Legacy contamination in secondary plastics, addressing the risk of materials and substances being inherited from the previous use and carried (circulated or transferred) through into new products when reprocessed material enters its subsequent use phase (recycled, secondary plastic); and, (2) Extrusion of secondary plastics during the final stage of conventional mechanical reprocessing. Based on selected literature, we semi-quantitatively assessed nine risk scenarios and ranked them according to the comparative magnitude of risk to human health. Our analysis highlights that despite stringent regulation, industrial diligence and enforcement, occasionally small amounts of potentially hazardous substances contained in waste plastics are able to pass through established safeguards and re-enter (cascade into) the next use phase (product cycle) after being recycled. Although many of these 'inherited' chemical substances are present at concentrations unlikely to pose a serious and imminent threat, their existence may indicate a wider or possible increase in pollution dispersion. Our assessment indicates that the highest risk results from exposure to these substances during extrusion by mechanical reprocessors in contexts where only passive ventilation, dilution and dispersion are used as control measures. Our work sets the basis to inform improved future risk management protocols for a non-polluting circular economy for plastics.

Type-dependent effects of microplastics on tomato (Lycopersicon esculentum L.): Focus on root exudates and metabolic reprogramming

Much attention has been paid to the prevalence of microplastics (MPs) in terrestrial systems. MPs have been shown to affect the physio-biochemical properties of plants. Different MPs may have distinctive behaviors and diverse effects on plant growth. In the present study, the effects of polystyrene (PS), polyethylene (PE), and polypropylene (PP) MPs on physio-biochemical properties, root exudates, and metabolomics of tomato (Lycopersicon esculentum L.) under hydroponic conditions were investigated. Our results show that MPs exposure has adverse effects on tomato growth. MPs exposure had a significant type-dependent effect (p < 0.001) on photosynthetic gas parameters, chlorophyll content, and antioxidant enzyme activities. After exposure to MPs, the content of low molecular weight organic acids in tomato root exudates was significantly increased, which was considered as a strategy to alleviate the toxicity of MPs. In addition, MPs treatment significantly changed the metabolites of tomato root and leaf. Metabolic pathway analysis showed that MPs treatment had a great effect on amino acid metabolism. We also found that plants exposed to PS and PP MPs produced more significant metabolic reprogramming than those exposed to PE MPs. This study provides important implications for the mechanism studies on the toxic effect of various MPs on crops and their future risk assessment.

A mechanistic understanding of the effects of polyethylene terephthalate nanoplastics in the zebrafish (Danio rerio) embryo

Plastic pollution, especially by nanoplastics (NPs), has become an emerging topic due to the widespread existence and accumulation in the environment. The research on bioaccumulation and toxicity mechanism of NPs from polyethylene terephthalate (PET), which is widely used for packaging material, have been poorly investigated. Herein, we report the first use of high-resolution magic-angle spinning (HRMAS) NMR based metabolomics in combination with toxicity assay and behavioural end points to get systems-level understanding of toxicity mechanism of PET NPs in intact zebrafish embryos. PET NPs exhibited significant alterations on hatching and survival rate. Accumulation of PET NPs in larvae were observed in liver, intestine, and kidney, which coincide with localization of reactive oxygen species in these areas. HRMAS NMR data reveal that PET NPs cause: (1) significant alteration of metabolites related to targeting of the liver and pathways associated with detoxification and oxidative stress; (2) impairment of mitochondrial membrane integrity as reflected by elevated levels of polar head groups of phospholipids; (3) cellular bioenergetics as evidenced by changes in numerous metabolites associated with interrelated pathways of energy metabolism. Taken together, this work provides for the first time a comprehensive system level understanding of toxicity mechanism of PET NPs exposure in intact larvae.

UV aging of microplastic polymers promotes their chemical transformation and byproduct formation upon chlorination

The presence and accumulation of microplastics (MPs) in water and wastewater is a growing concern. When released to the water bodies, microplastics can be subject to surface weathering due to ultraviolet (UV) exposure. In this study, the effects of UV aging of six MP polymers from three groups (e.g., polyamide, polyester, and polyolefin) on their chlorine reactivity, chemical transformation, and formation of disinfection byproducts (DBPs) were studied. Polyamide (e.g., polyamide 6) in both virgin and UV-aged forms showed significantly higher chlorine demands than other MP polymers (915.5-947.9 versus 7.0-21.1 μmol/g MP in 24 h), and polyolefins were relatively inert to chlorine. UV aging enhanced the destructions of functional groups of polyamide and polyester upon chlorination, promoting the chlorine demands and leaching of organics by up to 1.7- and 2.4-fold, respectively. Polymer monomer and oligomers of polyamide 6 and toxic or endocrine disrupting additives (e.g., dimethyl phthalate and butyl octyl phthalate) were identified in leachates from chlorinated MP polymers by mass spectrometry. Meanwhile, up to >10-fold increases in the yields of trihalomethane, haloacetic acid, haloacetaldehyde, haloacetonitrile, and haloacetamide were observed from 30-day UV-aged MP polymers as compared to their virgin counterparts. Overall, this study reveals that UV aging can promote the reactivity and chemical transformation of MP polymers during chlorination, especially for polyamide and polyester, increase the release of polymer monomers, oligomers, and additives, and aggravate the role of MP polymers as DBP precursors.

A circular polyester platform based on simple gem-disubstituted valerolactones

Geminal disubstitution of cyclic monomers is an effective strategy to enhance the chemical recyclability of their polymers, but it is utilized for that purpose alone and often at the expense of performance properties. Here we present synergistic use of gem-α,α-disubstitution of available at-scale, bio-based δ-valerolactones to yield gem-dialkyl-substituted valerolactones ([Formula: see text]), which generate polymers that solve not only the poor chemical recyclability but also the low melting temperature and mechanical performance of the parent poly(δ-valerolactone); the gem-disubstituted polyesters ([Formula: see text]) therefore not only exhibit complete chemical recyclability but also thermal, mechanical and transport properties that rival or exceed those of polyethylene. Through a fundamental structure-property study that reveals intriguing impacts of the alkyl chain length on materials performance of [Formula: see text], this work establishes a simple circular, high-performance polyester platform based on [Formula: see text] and highlights the importance of synergistic utilization of gem-disubstitution for enhancing both chemical recyclability and materials performance of sustainable polyesters.

Effects of microplastics on nitrogen and phosphorus cycles and microbial communities in sediments

Sediments are the long-term sinks of microplastics (MPs) and nutrients in freshwater ecosystems. Therefore, understanding the effect of MPs on sediment nutrients is crucial. However, few studies have discussed the effects of MPs on nitrogen and phosphorus cycles in freshwater sediments. Herein, 0.5% (w/w) polyvinyl chloride (PVC), polylactic acid (PLA), and polypropylene (PP) MPs were added to freshwater sediments to evaluate their effects on microbial communities and nitrogen and phosphorus release. The potential biochemical functions of the bacterial communities in the sediments were predicted and assessed via 16S rRNA gene sequencing. The results showed that MPs significantly affected the microbial community composition and nutrient cycling in the sediments. PVC and PP MPs can promote microbial nitrification and nitrite oxidation, while PP can significantly promote alkaline phosphatase (ALP) activity and the abundance of the phosphorus-regulation (phoR) gene. PLA MPs had the potential to promote the abundance of microbial phosphorus transporter (ugpB), nitrogen fixation (nifD, nifH, and nifX), and denitrification (nirS, napA, and norB) genes and inhibit nitrification, resulting in massive accumulation and release of ammonia nitrogen. Although PLA MPs inhibited the activity of ALP and the abundance of the organophosphorus mineralization (phoD) gene, it could enhance dissimilatory iron and sulfite reduction, which may promote the release of sedimentary phosphorus. Our findings may help understand the mechanisms of nitrogen and phosphorus cycles and microbial communities driven by MPs in sediments and provide a basis for future assessments of the environmental behavior of MPs in freshwater ecosystems.

A high-resolution dynamic probabilistic material flow analysis of seven plastic polymers; A case study of Norway

Plastic pollution has long been identified as one of the biggest challenges of the 21st century. To tackle this problem, governments are setting stringent recycling targets to keep plastics in a closed loop. Yet, knowledge of the stocks and flows of plastic has not been well integrated into policies. This study presents a dynamic probabilistic economy-wide material flow analysis (MFA) of seven plastic polymers (HDPE, LDPE, PP, PS, PVC, EPS, and PET) in Norway from 2000 to 2050. A total of 40 individual product categories aggregated into nine industrial sectors were examined. An estimated 620 ± 23 kt or 114 kg/capita of these seven plastic polymers was put on the Norwegian market in 2020. Packaging products contributed to the largest share of plastic put on the market (∼40%). The accumulated in-use stock in 2020 was about 3400 ± 56 kt with ∼60% remaining in buildings and construction sector. In 2020, about 460 ± 22 kt of plastic waste was generated in Norway, with half originating from packaging. Although ∼50% of all plastic waste is collected separately from the waste stream, only around 25% is sorted for recycling. Overall, ∼50% of plastic waste is incinerated, ∼15% exported, and ∼10% landfilled. Under a business-as-usual scenario, the plastic put on the market, in-use stock, and waste generation will increase by 65%, 140%, and 90%, respectively by 2050. The outcomes of this work can be used as a guideline for other countries to establish the stocks and flows of plastic polymers from various industrial sectors which is needed for the implementation of necessary regulatory actions and circular strategies. The systematic classification of products suitable for recycling or be made of recyclate will facilitate the safe and sustainable recycling of plastic waste into new products, cap production, lower consumption, and prevent waste generation.

Influence of waves on the three-dimensional distribution of plastic in the ocean

The world's oceans are facing plastic pollution, 80 % of which of terrestrial origin flowing from the mismanaged waste of coastal populations and from river discharge. To study the fate of this pollution, the three-dimensional trajectories of neutral plastic particles continuously released for 24 years according to realistic source scenarios are computed using currents from a global ocean-wave coupled model at 14^∘ resolution and from a reference ocean-only model. These Lagrangian simulations show that neutral particles accumulate at the surface in the subtropical convergence zones from where they penetrate to about 250 m depth and strongly disperse over 40^∘ of latitude. About 5.3 % of the particles remain at the surface with the wave-coupled model currents, whereas only 2 % for the uncoupled model, with some modulation in the location of the convergence zones. Increased surface retention results from upward vertical velocities induced by widespread divergence of waves-induced Stokes transport in the surface layers.

How does the "Zero-waste City" strategy contribute to carbon footprint reduction in China?

The "Zero-waste City" program and carbon peak plan are currently vital environmental strategies in China. Solid waste management systems are closely related to greenhouse gas emissions, and "Zero-waste City" programs are highlighted because of their great potential for carbon footprint reduction and pollution mitigation. However, a knowledge gap remains in terms of quantifying the carbon footprint when implementing "Zero-waste City" programs. Here, we developed a methodology for accounting for the carbon footprint of a solid waste management system, and Ningbo city, which is one of the first demonstration "Zero-waste Cities" in China, was chosen as the study case. The material flow and carbon footprint of construction and demolition waste, industrial waste, hazardous waste, sludge, and municipal solid waste were analyzed. The results show that the carbon footprint of the solid waste management system in Ningbo city was -1679.9 Gg CO₂_eq in 2018, which can be divided into 3472.5, 1131.3, and -6283.8 Gg CO₂_eq by Scopes 1, 2, and 3, respectively. According to the scenario analysis, the SWMS in Ningbo city can achieve a carbon footprint reduction potential of at least 5771.5 Gg CO₂_eq by 2025, by implementing the "Zero-waste City" strategy. This suggests that waste minimization, construction and demolition waste recycling, and municipal solid waste recycling are the most effective measures for carbon footprint reduction.

New Perspective on the Mobilization of Microplastics through Capillary Fringe Fluctuation in a Tidal Aquifer Environment

The presence of plastic fragments in the environment is a growing global concern. In this study, we explored the effects of dynamic fluctuations of capillary fringe on the transport of microplastics (MPs) in the substrate combining various environmental and MP properties. Both experimental and Hydrus-2D modeling results confirmed that increasing cycles of water table fluctuation led to the rise of capillary fringe. An increase in the cycles of water table fluctuations did not significantly change the overall MP retention percentages in 0.5 mm substrate but altered the MP distribution along the column. In 1 and 2 mm substrate, the increase in cycle numbers enhanced the MP transport from substrate to the water below. In terms of the size of the MPs, more 20-25 μm polyethylene (PE2) were retained in the substrate compared to 4-6 μm polyethylene (PE1) under the same number of fluctuation cycles. High-density polytetrafluoroethylene (PTFE, 5-6 μm) exhibited higher retention percentages compared to PE1 particles. Ultraviolet aging for 60 days enhanced PE1 transport along the column, while 60 days of seawater aging did not affect PE1 transport greatly. For PTFE, ultraviolet and seawater aging enhanced its retention in the substrate. The retention percentages of both PE1 and PTFE in the column increased with the elevated ionic strength and the decrease of fluctuation velocity. This work highlights that capillary fringe fluctuation can serve as a pathway to relocate MPs to the tidal aquifer.

Biodegradable blends from bacterial biopolyester PHBV and bio-based PBSA: Study of the effect of chain extender on the thermal, mechanical and morphological properties

Being aware of the global problem of plastic pollution, our society is claiming new bioplastics to replace conventional polymers. Balancing their mechanical performance is required to increase their presence in the market. Brittleness of bacterial poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) was attempted to be decreased by melt blending with flexible starch-based poly(butylene succinate-co-butylene adipate) (PBSA). An epoxy-functionalized chain extender was used to enhance interaction between both immiscible biopolyesters. Mechanical performance, morphology, rheology, and crystallization behavior of injection-molded PHBV-PBSA blends (70-30, 50-50, and 30-70 wt%) were assessed in the presence and absence of the chain extender. Crystallization of PHBV was hindered, which was reflected in the improvement of mechanical properties. When PBSA >50 %, the homogeneity of results increased within the same sample while for PHBV-PBSA 70-30 wt% the elongation was 45 % higher. During the flexural test, it changed from brittle to non-breakable. The additive did not change the type of morphology developed by each blend nor the toughening mechanisms, so impact strength was barely affected. However, it reduced the size of dispersed phase domains due to a viscosity change, improving their processability. The higher the PHBV in the blend, the higher the effect of the chain extender.

Mistaking plastic for zooplankton: Risk assessment of plastic ingestion in the Mediterranean sea

Floating plastic debris is a pervasive pollutant in seas and oceans, affecting a wide range of animals. In particular, microplastics (<5 mm in size) increase the possibility that marine species consume plastic and enter the food chain. The present study investigates this potential mistake between plastic debris and zooplankton by calculating the plastic debris to zooplankton ratio over the whole Mediterranean Sea. To this aim, in situ data from the Tara Mediterranean Expedition are combined with environmental and Lagrangian diagnostics in a machine learning approach to produce spatially-explicit maps of plastic debris and zooplankton abundance. We then analyse the plastic to zooplankton ratio in regions with high abundances of pelagic fish. Two of the major hotspots of pelagic fish, located in the Gulf of Gabès and Cilician basin, were associated with high ratio values. Finally, we compare the plastic to zooplankton ratio values in the Pelagos Sanctuary, an important hotspot for marine mammals, with other Geographical Sub-Areas, and find that they were among the larger of the Western Mediterranean Sea. Our results indicate a high potential risk of contamination of marine fauna by plastic and advocate for novel integrated modelling approaches which account for potential trophic transfer within the food chain.

Adverse effects of polystyrene microplastics in the freshwater commercial fish, grass carp (Ctenopharyngodon idella): Emphasis on physiological response and intestinal microbiome

Microplastics (MPs) pollution in aquatic environment has attracted global attention in recent years. To evaluate the potential toxic effects of MPs in freshwater cultured fish, grass carps (Ctenopharyngodon idella) (body length: 7.7 ± 0.1 cm, wet weight: 6.28 ± 0.23 g) were exposed to different sizes (0.5 μm, 15 μm) and concentrations (100 μg/L, 500 μg/L) of polystyrene microplastics (PS-MPs) suspension for 7 and 14 days, followed by 7 days of depuration, detecting the variations in growth rate, histological structure, oxidative response and intestinal microbiome. Our results indicate that MP toxicity elicited significant size- and concentration-dependent responses by grass carp. MP exposure caused obvious decrease in growth rate on day 14 but not on day 7. Additionally, MPs with large size and high concentration caused more severe intestinal damage and less weight gain, while MP particles with small size and high concentration induced more severe liver congestion and stronger oxidative stress. MP exposure dramatically shifted the gut microbial composition, with the top 10 genera in abundance being associated with the diameter and concentration of the MPs. After 7 days of depuration, only superoxide dismutase and malondialdehyde in liver, showed a tendency to recover to the initial values. Even though the differences in the gut microbial community between the control and treatment groups disappeared, and the proportion of potential pathogenic bacteria in intestine was still high. Thus, it is clear that a short-term depuration period of 7 days is not enough for complete normalization.

Satellite monitoring of terrestrial plastic waste

Plastic waste is a significant environmental pollutant that is difficult to monitor. We created a system of neural networks to analyze spectral, spatial, and temporal components of Sentinel-2 satellite data to identify terrestrial aggregations of waste. The system works at wide geographic scale, finding waste sites in twelve countries across Southeast Asia. We evaluated performance in Indonesia and detected 374 waste aggregations, more than double the number of sites found in public databases. The same system deployed in Southeast Asia identifies 996 subsequently confirmed waste sites. For each detected site, we algorithmically monitor waste site footprints through time and cross-reference other datasets to generate physical and social metadata. 19% of detected waste sites are located within 200 m of a waterway. Numerous sites sit directly on riverbanks, with high risk of ocean leakage.

Plastic is a widely used and selectively chosen nesting material for pied flycatchers (Ficedula hypoleuca) in rural woodland habitats

There is increasing concern about the burgeoning effects of discarded plastic on the earth's biodiversity. Quantifying the presence of plastic and other anthropogenic waste in the environment can be logistically and financially challenging, although it is possible that bird' nests can be used as bioindicators. Many birds in heavily modified terrestrial ecoystems, such as urban environments, incorporate plastic and other anthropogenic materials into their nests but our understanding of the presence of discarded plastic in nests in rural woodlands remains poor. Here, we show that plastic and other anthropogenic materials were present in 35 % of 325 pied flycatcher (Ficedula hypoleuca) nests from 17 rural woodlands throughout Great Britain, although the woodlands did vary in the amount of material incorporated into nests. Then, in an experimental test at one study site, where flycatchers were provided with a choice of two types of natural and two types of anthropogenic nest materials, they preferentially selected one natural and one anthropogenic material. In another test, the flycatchers were provided with plastic of four colours and overwhelmingly selected white and avoided orange, blue and yellow plastic. Although the flycatcher's selectivity for certain material types and colours preclude their nests being a reliable indicator of plastic in the environment, our study nonetheless demonstrates that bird species incorporate anthropogenic materials, such as plastic, into their nests in rural woodlands.

Consequences of in vitro benzyl butyl phthalate exposure for blubber gene expression and insulin-induced Akt activation in juvenile grey seals

Plastic and plasticiser pollution of marine environments is a growing concern. Although phthalates, one group of plasticisers, are rapidly metabolised by mammals, they are found ubiquitously in humans and have been linked with metabolic disorders and altered adipose function. Phthalates may also present a threat to marine mammals, which need to rapidly accumulate and mobilise their large fat depots. High molecular weight (HMW) phthalates may be most problematic because they can accumulate in adipose. We used blubber explants from juvenile grey seals to examine the effects of overnight exposure to the HMW, adipogenic phthalate, benzyl butyl phthalate (BBzP) on expression of key adipose-specific genes and on phosphorylation of Akt in response to insulin. We found substantial differences in transcript abundance of Pparγ, Insig2, Fasn, Scd, Adipoq and Lep between moult stages, when animals were also experiencing differing mass changes, and between tissue depths, which likely reflect differences in blubber function. Akt abundance was higher in inner compared to outer blubber, consistent with greater metabolic activity in adipose closer to muscle than skin, and its phosphorylation was stimulated by insulin. Transcript abundance of Pparγ and Fasn (and Adipoq in some animals) were increased by short term (30 min) insulin exposure. In addition, overnight in vitro BBzP exposure altered insulin-induced changes in Pparγ (and Adipoq in some animals) transcript abundance, in a tissue depth and moult stage-specific manner. Basal or insulin-induced Akt phosphorylation was not changed. BBzP thus acted rapidly on the transcript abundance of key adipose genes in an Akt-independent manner. Our data suggest phthalate exposure could alter seal blubber development or function, although the whole animal consequences of these changes are not yet understood. Knowledge of typical phthalate exposures and toxicokinetics would help to contextualise these findings in terms of phthalate-induced metabolic disruption risk and consequences for marine mammal health.

A growing plastic smog, now estimated to be over 170 trillion plastic particles afloat in the world's oceans-Urgent solutions required

As global awareness, science, and policy interventions for plastic escalate, institutions around the world are seeking preventative strategies. Central to this is the need for precise global time series of plastic pollution with which we can assess whether implemented policies are effective, but at present we lack these data. To address this need, we used previously published and new data on floating ocean plastics (n = 11,777 stations) to create a global time-series that estimates the average counts and mass of small plastics in the ocean surface layer from 1979 to 2019. Today's global abundance is estimated at approximately 82-358 trillion plastic particles weighing 1.1-4.9 million tonnes. We observed no clear detectable trend until 1990, a fluctuating but stagnant trend from then until 2005, and a rapid increase until the present. This observed acceleration of plastic densities in the world's oceans, also reported for beaches around the globe, demands urgent international policy interventions.

Ingestion of microplastics and textile cellulose particles by some meiofaunal taxa of an urban stream

Microplastics (MPs) and textile cellulose are globally pervasive pollutants in freshwater. In-situ studies assessing the ingestion of MPs by freshwater meiofauna are few. Here, we evaluated MP and textile cellulose ingestion by some meiofaunal taxa and functional guilds of a first-order stream in the city of Florence (Italy) by using a tandem microscopy approach (fluorescence microscopy and μFTIR). The study targeted five taxa (nematodes, oligochaetes, copepods, ephemeropterans and chironomids), three feeding (scrapers, deposit-feeders, and predators), and three locomotion (crawlers, burrowers, and swimmers) guilds. Fluorescent particles related to both MPs and textile cellulose resulted in high numbers in all taxa and functional guilds. We found the highest number of particles in nematodes (5200 particles/ind.) and deposit-feeders (1693 particles/ind.). Oligochaetes and chironomids (burrowers) ingested the largest particles (medium length: 28 and 48 μm, respectively), whereas deposit-feeders ingested larger particles (medium length: 26 μm) than scrapers and predators. Pellets were abundant in all taxa, except for Chironomidae. Textile cellulose fibers were present in all taxa and functional guilds, while MP polymers (EVA, PET, PA, PE, PE-PP) differed among taxa and functional guilds. In detail: EVA and PET particles were found only in chironomids, PE particles occurred in chironomids, copepods and ephemeropterans, PA particles were found in all taxa except in nematodes, whereas particles made of PE-PP blend occurred in oligochaetes and copepods. Burrowers and deposit-feeders ingested EVA, PET, PA, PE and PE-PP, while crawlers and scrapers ingested PE and PA. Swimmers and predators ingested PE, PA and PE-PP. Our findings suggest a pervasive level of plastic and textile cellulose pollution consistent with an urban stream which propagates in the meiofaunal assemblage of the stream ecosystem.

Role of polyamide microplastic in altering microbial consortium and carbon and nitrogen cycles in a simulated agricultural soil microcosm

Microplastics (MPs) are persistent organic pollutants globally, with a continuous increase in MP wastes near and away from the regions of human activities. Studies to date aimed to explore the impact of MPs on ecosystems, but the area of research could not go beyond environmental pollution caused by MPs. To address the menace of MPs, scientists need to pay enough attention to the biogeochemical cycles, microbial communities, and functional microorganisms. Hence, this study aimed to evaluate the impact of adding 0.3% (mass ratio) [low-concentration (LC) group] and 1% [high-concentration (HC) group] of polyamide (PA) MP to the soil microenvironment with regard to the aforementioned parameters. PA MP decreased the soil microbial diversity (Shannon and Simpson indices, P < 0.05). At the phylum level, PA MP increased the abundance of Acidobacteria, Firmicutes, and Crenarchaeota (P < 0.05); at the genus level, it enhanced that of Geobacter, Thiobacillus, Pseudomonas, and Bradyrhizobium (P < 0.01) while decreased that of Bacillus, Flavisolibacter, Geothrix, and Pseudarthrobacter (P < 0.05). PA MP affected the carbon (C) cycle. PA MP accelerated the soil C fixation by enhancing the abundance of the genes accA and pccA. The LC PA MP accelerated organic C degradation and methane metabolism by changing the abundance of mnp, chiA, mcrA, pmoA, and mmoX genes, while the HC PA MP inhibited them with increasing the experimental time. Regarding the effects of PA on the nitrogen (N) cycle, the PA MP promoted N assimilation and ammonification by increasing the abundance of the genes gdh and ureC, the impact of PA MP on N fixation and denitrification depended on its concentration and treating time. This study showed that PA MP impacted the microbial consortium, it also affected the C and N cycles and its effect depended on its concentration and the treating time.

Assessing regional emissions of vehicle-based tire wear particle from macro-to micro/nano-scales with pandemic lockdowns and electromobility scenarios implications

Despite increasing the public awareness of ubiquity of microplastics (MPs) in air, the issue on particular source of tire wear particles (TWPs) emission into atmosphere and their exposure-associated human health has not received the attention it deserves. Here we linked vehicle kilometers traveled (VKT) estimates covering demography, socio-environmental, and transportation features and emission factors to predict regional emission patterns of TWP-derived atmospheric MPs. A data-driven probabilistic approach was developed to consider variability across the datasets and uncertainty of model parameters in terms of country-level and vehicle-type emissions. We showed that country-specific VKT from billion to trillion vehicle-kilometer resulted in 103-105 metric tons of airborne TWP-derived atmospheric MPs annually in the period 2015-2019, with the highest emissions from passenger cars and heavy-duty vehicles. On average, we found that airborne TWP emissions from passenger cars by country had substantial decreased (up to ∼33%) during COVID-19 lockdowns in 2020 and pronounced increased (by a factor ∼1.9) from vehicle electrification by the next three decades. We conclude that the stunning mass of airborne TWP is a predominant source of atmospheric MP. We underscore the necessity of TWP emissions control among the United States, China, and India. Our findings can be of great use to environmental transportation planners for devising vehicle/tire-oriented decision support tools. Our data offer information to enhance TWP-exposure estimates, to examine long-term exposure trends, and subsequently to improve health risk assessment during pandemic outbreak and future electrification.

Marine litter on the beaches of the Kanyakumari, Southern India: An assessment of their abundance and pollution indices

The problem of marine litter is increasing along the Indian coast. For conducting a baseline study to identify and assess the abundance, clean-coast index (CCI), and plastics abundance index (PAI) of marine litter were calculated on the beaches of Kanyakumari, Southern India. A total of 11,439 marine litter items were collected and classified into 33 groups along the 7 beaches of Kanyakumari. From the results, plastics were the most abundant items (65.08 %) followed by foam (21.93 %), along with cloths (4.59 %), rubber (3.09 %), papers (2.26 %), glass (2.16 %), metal (0.38 %), wood (0.26 %), and others (0.26 %). The average CCI value (27.24) indicates that all beaches are 'extremely dirty'; however, the PAI average value (4.37) indicates 'high abundance'. About 96.87 % of the marine litter originates from the land-based sources. This study provides an interpretive framework for further plastic pollution assessment, which could lead to a better marine litter management on Indian beaches.

Individual and combined toxicity of microplastics and diuron differs between freshwater and marine diatoms

Microplastics are considered as the emerging pollutants, which not only directly affect aquatic organisms, but also causes combined pollution by adsorbing other pollutants. Diuron, as one of the most widely used herbicides, is frequently monitored in the aquatic environment for its adverse effects on aquatic organisms. However, little is known about the combined toxicity of microplastics and diuron to aquatic organisms, especially diatoms. In this study, freshwater diatom (Cyclotella meneghiniana) and marine diatom (Skeletonema costatum) were selected to study the individual and combined toxicity of microplastics (polystyrene, 0.6- 1.0 μm) and diuron. Experimental concentrations of microplastics and diuron were set at 50 mg/L and 100 μg/L, respectively, which have been shown to significantly inhibit the growth of aquatic organisms. Results suggested that both single microplastics and single diuron significantly inhibited the growth of the two diatoms, while significant SOD and MDA increase were only found in single diuron exposure. For diatoms exposed to individual microplastics, the microplastic particles adsorbed inside Cyclotella sp. and those aggregated around Skeletonema sp. were the major factor inhibiting the growth of diatom, respectively. According to the independent action model, the combined toxicity for both diatoms were all antagonistic. The adsorption behavior of microplastics to diuron alleviated the intracellular damage to diatoms caused by diuron, and the oxidative stress induced by diuron mitigated the physical damage to diatoms caused by microplastics. Collectively, our findings suggest that the co-existence of microplastics and diuron may affect their respective toxicity to diatoms. The mechanism of this "cross-phenomenon" between microplastics and diuron and their combined toxicity to different aquatic organisms need to be further studied.

Flow and stock accumulation of plastics in China: Patterns and drivers

Plastic pollution has always been a hot issue of global concern. Previous studies have mainly focused on the flow of plastics. However, information on the patterns and characteristics of flow, stock, and waste in the plastic life cycle and their driving factors is limited in China, and effective waste reduction and sustainable strategies are missing. Therefore, this research established a flow model of polyethylene (PE), polypropylene (PP), and polyethylene terephthalate (PET); further analyzed the driving factors; and proposed strategies for waste reduction and sustainable development. We found that the total consumption, stock, and waste of PET, PE, and PP in 2010-2017 reached 552.96, 292.70, and 257.18 Tg, respectively. Building and construction (B&C), packaging, and textiles were the sectors with the largest stock of PE, PP, and PET. From 2010 to 2013, the stock of PE increased by 440 %, which was mainly driven by the increase in material utilization intensity (MUI). Similarly, the growth of MUI was the main driving factor driving PP (351 %) and PET (367 %) stocks. Notably, from 2014 to 2017, economic growth was the main factor driving the plastic stock. These results will provide a scientific basis for promoting the sustainable utilization of PE, PP, and PET and be of great significance to achieve the strategic goal of a no-waste city.

Integrating a Chemicals Perspective into the Global Plastic Treaty

Driven by the growing concern about plastic pollution, countries have agreed to establish a global plastic treaty addressing the full life cycle of plastics. However, while plastics are complex materials consisting of mixtures of chemicals such as additives, processing aids, and nonintentionally added substances, it is at risk that the chemical aspects of plastics may be overlooked in the forthcoming treaty. This is highly concerning because a large variety of over 10,000 chemical substances may have been used in plastic production, and many of them are known to be hazardous to human health and the environment. In this Global Perspective, we further highlight an additional, generally overlooked, but critical aspect that many chemicals in plastics hamper the technological solutions envisioned to solve some of the major plastic issues: mechanical recycling, waste-to-energy, chemical recycling, biobased plastics, biodegradable plastics, and durable plastics. Building on existing success stories, we outline three concrete recommendations on how the chemical aspects can be integrated into the global plastic treaty to ensure its effectiveness: (1) reducing the complexity of chemicals in plastics, (2) ensuring the transparency of chemicals in plastics, and (3) aligning the right incentives for a systematic transition.

From Food to Gods to Food to Waste

The present global food waste problem threatens food systems sustainability and our planet. The generation of food waste stems from the interacting factors of the need for food production, food access and availability, motivations and ignorance around food purchase and consumption, and market constraints. Food waste has increased over time. This is related to the change in how humans value food through the generations and altered human food consumption and food discard behaviors. There is also a lack of understanding of the impacts of current food production, processing and consumption patterns on food waste creation. This review examines the cultural, religious, social and economic factors influencing attitudes to food and their effects on food waste generation. The lessons from history about how humans strove toward zero waste are covered. We review the important drivers of food waste: waste for profit, food diversion to feed, waste for convenience, labeling, food service waste and household food waste. We discuss strategies for food waste reduction: recovery of food and food ingredients, waste conversion to energy and food, reducing waste from production/processing and reducing consumer food waste, and emphasize the need for all stakeholders to work together to reduce food waste.

Plastisphere showing unique microbiome and resistome different from activated sludge

Plastisphere (the biofilm on microplastics) in wastewater treatment plants (WWTPs) may enrich pathogens and antibiotic resistance genes (ARGs) which can cause risks to the ecological environment by discharging into receiving waters. However, the microbiome and resistome of plastisphere in activated sludge (AS) systems remain inconclusive. Here, metagenome was applied to investigate the microbial composition, functions and ARGs of the Polyvinyl chloride (PVC) plastisphere in lab-scale reactors, and revealed the effects of tetracycline (TC) and/or Cu(II) pressures on them. The results indicated that the plastisphere provided a new niche for microbiota showing unique functions distinct from the AS. Particularly, various potentially pathogenic bacteria tended to enrich in PVC plastisphere. Moreover, various ARGs were detected in plastisphere and AS, but the plastisphere had more potential ARGs hosts and a stronger correlation with ARGs. The ARGs abundances increased after exposure to TC and/or Cu(II) pressures, especially tetracycline resistance genes (TRGs), and the results further showed that TRGs with different resistance mechanisms were separately enriched in plastisphere and AS. Furthermore, the exogenous pressures from Cu(II) or/and TC also enhanced the association of potential pathogens with TRGs in PVC plastisphere. The findings contribute to assessing the potential risks of spreading pathogens and ARGs through microplastics in WWTPs.

Effects of the Antidepressant Amitriptyline on Juvenile Brown Trout and Their Modulation by Microplastics

Pharmaceuticals such as antidepressants are designed to be bioactive at low concentrations. According to their mode of action, they can also influence non-target organisms due to the phylogenetic conservation of molecular targets. In addition to the pollution by environmental chemicals, the topic of microplastics (MP) in the aquatic environment came into the focus of scientific and public interest. The aim of the present study was to investigate the influence of the antidepressant amitriptyline in the presence and absence of irregularly shaped polystyrene MP as well as the effects of MP alone on juvenile brown trout (Salmo trutta f. fario). Fish were exposed to different concentrations of amitriptyline (nominal concentrations between 1 and 1000 µg/L) and two concentrations of MP (104 and 105 particles/L; <50 µm) for three weeks. Tissue cortisol concentration, oxidative stress, and the activity of two carboxylesterases and of acetylcholinesterase were assessed. Furthermore, the swimming behavior was analyzed in situations with different stress levels. Exposure to amitriptyline altered the behavior and increased the activity of acetylcholinesterase. Moreover, nominal amitriptyline concentrations above 300 µg/L caused severe acute adverse effects in fish. MP alone did not affect any of the investigated endpoints. Co-exposure caused largely similar effects such as the exposure to solely amitriptyline. However, the effect of amitriptyline on the swimming behavior during the experiment was alleviated by the higher MP concentration.

Plastic pollution: the science we need for the planet we want

Plastics are incredibly versatile materials that can bring diverse societal and environmental benefit, yet current practices of production, use and disposal have negative effects on wildlife, the environment and human health leading to growing concern across public, policy makers and industry. This Special Issue in Emerging Topics in Life Sciences describes recent advances in our understanding of the consequences of plastic pollution. In particular, it examines their potential to act as vectors for chemicals and pathogens in the environment; evaluates the effects of plastic pollution on biogeochemical cycling, ecosystem functioning and highlights the potential for enhanced effects in environments that are already subject to substantive changes in their climate. The impacts plastics pose to terrestrial ecosystems including soil communities are described and evaluated, along with evidence of potential issues for human health. With an increase in the production of plastics labelled as 'biodegradable' their context and ecological impacts are reviewed. Finally, we discuss the need to take an integrative, system approach when developing and evaluating solutions to plastic pollution, to achieve the ambitious yet necessary aims of the UN Plastics Treaty.

Scaling up resource recovery of plastics in the emergent circular economy to prevent plastic pollution: Assessment of risks to health and safety in the Global South

Over the coming decades, a large additional mass of plastic waste will become available for recycling, as efforts increase to reduce plastic pollution and facilitate a circular economy. New infrastructure will need to be developed, yet the processes and systems chosen should not result in adverse effects on human health and the environment. Here, we present a rapid review and critical semi-quantitative assessment of the potential risks posed by eight approaches to recovering value during the resource recovery phase from post-consumer plastic packaging waste collected and separated with the purported intention of recycling. The focus is on the Global South, where there are more chances that high risk processes could be run below standards of safe operation. Results indicate that under non-idealised operational conditions, mechanical reprocessing is the least impactful on the environment and therefore most appropriate for implementation in developing countries. Processes known as 'chemical recycling' are hard to assess due to lack of real-world process data. Given their lack of maturity and potential for risk to human health and the environment (handling of potentially hazardous substances under pressure and heat), it is unlikely they will make a useful addition to the circular economy in the Global South in the near future. Inevitably, increasing circular economy activity will require expansion towards targeting flexible, multi-material and multilayer products, for which mechanical recycling has well-established limitations. Our comparative risk overview indicates major barriers to changing resource recovery mode from the already dominant mechanical recycling mode towards other nascent or energetic recovery approaches.

Plastic futures and their CO2 emissions

Plastics show the strongest production growth of all bulk materials and are already responsible for 4.5% of global greenhouse gas emissions^1,2. If no new policies are implemented, we project a doubling of global plastic demand by 2050 and more than a tripling by 2100, with an almost equivalent increase in CO₂ emissions. Here we analyse three alternative CO₂ emission-mitigation pathways for the global plastics sector until 2100, covering the entire life cycle from production to waste management. Our results show that, through bio-based carbon sequestration in plastic products, a combination of biomass use and landfilling can achieve negative emissions in the long term; however, this involves continued reliance on primary feedstock. A circular economy approach without an additional bioeconomy push reduces resource consumption by 30% and achieves 10% greater emission reductions before 2050 while reducing the potential of negative emissions in the long term. A circular bioeconomy approach combining recycling with higher biomass use could ultimately turn the sector into a net carbon sink, while at the same time phasing out landfilling and reducing resource consumption. Our work improves the representation of material flows and the circular economy in global energy and emission models, and provides insight into long-term dynamics in the plastics sector.

How far are we from robust estimates of plastic litter leakage to the environment?

Litter pollution is a global concern, and identifying sources and pathways is crucial for proposing preventative actions. Existing models of plastic litter leakage to the environment have provided worldwide estimates at a country-based level, but only a few initiatives address subnational scales. Adding relevant parameters and improving models is needed to reduce the limitations of global estimates. However, availability of information, which varies among countries and is critical in the Global South, may preclude such improvements. To understand the potentialities and limitations of subnational estimates of plastic litter leakage to the environment, we reviewed the parameters used in the literature and addressed data usability, considering Brazil as a case study. We gathered data on parameters identified for all 5570 Brazilian municipalities and evaluated their usability considering reliability and temporal and geographic granularity. We identified 51 parameters that are either currently used in models or could improve estimates, including parameters regarding territory, population density, socioeconomic condition, and solid waste generation, composition, collection, and final destination, selective waste collection, recycling, and hydrology. Only 29.4% of parameters were linked to data sources with good or very good usability, while most of them presented average usability (45.1%) and 7.8% were not linked to any data source. This panorama of low data usability reveals uncertainties and explicit difficulties of estimating plastic litter leakage to the environment, including mobilization from the terrestrial environment to the ocean. The Brazilian scenario reflects current data availability conditions and the difficulties of countries in the Global South to robustly understand plastic litter leakage and face land-based sources of marine litter.

The ecological impact of plastic pollution in a changing climate

Assessing three interlinked issues, plastic pollution, climate change and biodiversity loss separately can overlook potential interactions that may lead to positive or negative impacts on global ecosystem processes. Recent studies suggest that threatened species and ecosystems are vulnerable to both plastic pollution and climate change stressors. Here we consider the connectivity and state of knowledge between these three environmental issues with a focus on the Global South. Nine out of top ten Long-Term Climate Risk Index (CRI) (2000-2019) ranked countries are located within the Global South, yet research is focused in the Global North. A literature search for the top ten Long-Term Climate Risk Index (CRI) (2000-2019) ranked countries matched a total of 2416 (3.3% of global publications) search results on climate change, with 56 (4% of the global publications) on plastic pollution, and seven (7.7% of the global publications) on both climate change and plastic pollution. There is a strong correlation between the Global South and high biodiversity hotspots, high food insecurity and low environmental performance. Using Bangladesh as a case study, we show the erosion rates and sea level rise scenarios that will increase ocean-bound plastic pollution and impact high biodiversity areas. Poverty alleviation and promoting renewable energy and green practices can significantly reduce the stress on the environment. We recommend that these connected planetary threats can be best addressed through a holistic and collaborative approach to research, a focus on the Global South, and an ambitious policy agenda.

Plastic pollution requires an integrative systems approach to understand and mitigate risk

To date, much effort has been placed on quantifying plastic pollution and understanding its negative environmental effects, arguably to the detriment of research and evaluation of potential interventions. This has led to piecemeal progress in interventions to reduce plastic pollution, which do not correspond to the pace of emissions. For substances that are used on a global scale and identified as hazardous, there is a need to act before irreversible damage is done. For example, the history of dichlorodiphenyltrichloethane's (DDT) use has demonstrated that legacy chemicals with properties of persistence can still be found in the environment despite being first prohibited 50 years ago. Despite the growing evidence of harm, evidence to inform actions to abate plastic pollution lag behind. In part, this is because of the multifaceted nature of plastic pollution and understanding the connections between social, economic and environmental dimensions are complex. As such we highlight the utility of integrative systems approaches for addressing such complex issues, which unites a diversity of stakeholders (including policy, industry, academia and society), and provides a framework to identify to develop specific, measurable and time-bound international policies on plastic pollution and meet the ambitious yet necessary goals of the UN Plastic Treaty.

The gut microbiota, a key to understanding the health implications of micro(nano)plastics and their biodegradation

The effects of plastic debris on the environment and plant, animal, and human health are a global challenge, with micro(nano)plastics (MNPs) being the main focus. MNPs are found so often in the food chain that they are provoking an increase in human intake. They have been detected in most categories of consumed foods, drinking water, and even human feces. Therefore, oral ingestion becomes the main source of exposure to MNPs, and the gastrointestinal tract, primarily the gut, constantly interacts with these small particles. The consequences of human exposure to MNPs remain unclear. However, current in vivo studies and in vitro gastrointestinal tract models have shown that MNPs of several types and sizes impact gut intestinal bacteria, affecting gut homeostasis. The typical microbiome signature of MNP ingestion is often associated with dysbiosis and loss of resilience, leads to frequent pathogen outbreaks, and local and systemic metabolic disorders. Moreover, the small micro- and nano-plastic particles found in animal tissues with accumulated evidence of microbial degradation of plastics/MNPs by bacteria and insect gut microbiota raise the issue of whether human gut bacteria make key contributions to the bio-transformation of ingested MNPs. Here, we discuss these issues and unveil the complex interplay between MNPs and the human gut microbiome. Therefore, the elucidation of the biological consequences of this interaction on both host and microbiota is undoubtedly challenging. It is expected that microbial biotechnology and microbiome research could help decipher the extent to which gut microorganisms diversify and MNP-determinant species, mechanisms, and enzymatic systems, as well as become important to understand our response to MNP exposure and provide background information to inspire future holistic studies.

Voluntary commitments made by the world's largest companies focus on recycling and packaging over other actions to address the plastics crisis

Plastic pollution has caused significant environmental and health challenges. Corporations that contribute to the make, use, and distribution of plastics can play a vital role in addressing global plastic pollution and many are committing to voluntary pledges. However, the extent to which corporation voluntary commitments are helping solve the problem remains underexplored. Here we develop a novel typology to characterize voluntary commitments to reduce plastic pollution made between 2015-2020 by 974 companies including the top 300 of the Fortune Global. We find that 72% of these companies have made commitments to reduce plastic pollution. About 67% of companies participating in voluntary environmental programs (VEPs) and 17% of non-VEPs participants made measurable and timebound commitments. However, rather than tackle virgin plastics, most companies target general plastics and frequently emphasize end-of-life controls with a primary focus on recycling. Growing commitments on plastic pollution are made by large and important companies, but significantly more efforts beyond plastic recycling are required to effectively address plastic pollution challenges.

Remediation technology towards zero plastic pollution: Recent advance and perspectives

The rapid growth of plastic wastes exceeds efforts to eliminate plastic pollution owing to the outbreak of COVID-19 in 2020 and then aggravates inherent environmental threats to the ecosystem. The paper provided a short introduction relating to the hazards of plastic wastes on environment and a detailed statement about plastic toxicity on human. The article stated on plastic how to enter the body and cause harm for us step by step. Given the toxicity and harm of plastic wastes on human, the degradation of plastic wastes via the physical, chemical and biotic methodologies is looked back. The advanced physical techniques are introduced briefly at firstly. Additionally, evaluate on chemical method for plastic decomposition and review on biotic degradation of plastic. The reactive oxygen species and the enzymes play a crucial role in chemical and biotic degradation processes, respectively. The reactive oxygen species are derived from the activated state of oxides, and the enzymes that aid the microorganism to ingest plastic through its metabolic mechanism are secreted by the microorganism. Subsequently, the potential possibility of upcycling plastic is analyzed from two aspects of the technology and application. The innovative technology utilizes sunlight as driver-power of plastic upcycling. And the carbon capture, utilization and sequestration and the growth substrate provided the novel guided directions for plastic recycle. Lastly, the three suggestions on plastic waste management are expected to establish an economy and efficient plastic sorting system, and two engineering solutions on plastic recycle are to make a contribution for sustainable upcycling of plastic.

A whale of a plastic tale: A plea for interdisciplinary studies to tackle micro- and nanoplastic pollution in the marine realm

Plastic is one of the most ubiquitous sources of both contamination and pollution of the Anthropocene, and accumulates virtually everywhere on the planet. As such, plastic threatens the environment, the economy and human well-being globally. The related potential threats have been identified as a major global conservation issue and a key research priority. As a consequence, plastic pollution has become one of the most prolific fields of research in research areas including chemistry, physics, oceanography, biology, ecology, ecotoxicology, molecular biology, sociology, economy, conservation, management, and even politics. In this context, one may legitimately expect plastic pollution research to be highly interdisciplinary. However, using the emerging topic of microplastic and nanoplastic leachate (i.e., the desorption of molecules that are adsorbed onto the surface of a polymer and/or absorbed into the polymer matrix in the absence of plastic ingestion) in the ocean as a case study, we argue that this is still far from being the case. Instead, we highlight that plastic pollution research rather seems to remain structured in mostly isolated monodisciplinary studies. A plethora of analytical methods are now available to qualify and quantify plastic monomers, polymers and the related additives. We nevertheless show though a survey of the literature that most studies addressing the effects of leachates on marine organisms essentially still lack of a quantitative assessment of the chemical nature and content of both plastic items and their leachates. In the context of the ever-increasing research effort devoted to assess the biological and ecological effects of plastic waste, we subsequently argue that the lack of a true interdisciplinary approach is likely to hamper the development of this research field. We finally introduce a roadmap for future research which has to evolve through the development of a sound and systematic ability to chemically define what we biologically compare.

Anthropocene microplastic stratigraphy of Xiamen Bay, China: A history of plastic production and waste management

Microplastics (MPs) are considered one of the significant stratigraphic markers of the onset of the Anthropocene Epoch; however, the interconnections between historic plastic production, waste management as well as social-economic and timing of MP accumulation are not well understood. Here, stratigraphic data of MPs from a sediment core from Xiamen Bay, China, was used to reconstruct the history of plastic pollution. Generalized Additive Modeling indicates a complex temporal evolution of MP accumulation. The oldest MPs deposited in 1952 was 30,332 ± 31,457 items/kg•dw, coincide with the infancy of the plastic industry and onset of the Anthropocene. The Cultural Revolution (1966-1976) curtailed these initial increases. Subsequent rapid growth in MPs during the late 1970s was peaked at 189,241 ± 29,495 items/kg•dw in 1988 and was followed by a drastic decline in the late 1980s to a low value in 1996 (16,626 ± 26,371 items/kg•dw), coinciding with proliferation of MP sources, coupled with evolution of plastic production, consumption, and regulation. Increasing MPs over the past decades implies that previous mitigation measures have been compromised by the escalated influx of MPs from increasing plastics production, legacy MPs remaining in circulation and insufficient waste management for a growing population. The present methodology and results represent a conceptual advance in understanding how changes in policy and economics over time correlate to changes in MP records in Anthropocene strata, which may help make decisions on plastic pollution mitigation strategies worldwide.

The quest for the missing plastics: Large uncertainties in river plastic export into the sea

Plastic pollution in the natural environment is causing increasing concern at both the local and global scale. Understanding the dispersion of plastic through the environment is of key importance for the effective implementation of preventive measures and cleanup strategies. Over the past few years, various models have been developed to estimate the transport of plastics in rivers, using limited plastic observations in river systems. However, there is a large discrepancy between the amount of plastic being modelled to leave the river systems, and the amount of plastic that has been found in the seas and oceans. Here, we investigate one of the possible causes of this mismatch by performing an extensive uncertainty analysis of the riverine plastic export estimates. We examine the uncertainty from the homogenisation of observations, model parameter uncertainty, and underlying assumptions in models. To this end, we use the to-date most complete time-series of macroplastic observations (macroplastics have been found to contain most of the plastic mass transported by rivers), coming from three European rivers. The results show that model structure and parameter uncertainty causes up to four orders of magnitude, while the homogenisation of plastic observations introduces an additional three orders of magnitude uncertainty in the estimates. Additionally, most global models assume that variations in the plastic flux are primarily driven by river discharge. However, we show that correlations between river discharge (and other environmental drivers) and the plastic flux are never above 0.5, and strongly vary between catchments. Overall, we conclude that the yearly plastic load in rivers remains poorly constrained.

Plastic leachates impair picophytoplankton and dramatically reshape the marine microbiome

BACKGROUND

Each year, approximately 9.5 million metric tons of plastic waste enter the ocean with the potential to adversely impact all trophic levels. Until now, our understanding of the impact of plastic pollution on marine microorganisms has been largely restricted to the microbial assemblages that colonize plastic particles. However, plastic debris also leaches considerable amounts of chemical additives into the water, and this has the potential to impact key groups of planktonic marine microbes, not just those organisms attached to plastic surfaces.

RESULTS

To investigate this, we explored the population and genetic level responses of a marine microbial community following exposure to leachate from a common plastic (polyvinyl chloride) or zinc, a specific plastic additive. Both the full mix of substances leached from polyvinyl chloride (PVC) and zinc alone had profound impacts on the taxonomic and functional diversity of our natural planktonic community. Microbial primary producers, both prokaryotic and eukaryotic, which comprise the base of the marine food web, were strongly impaired by exposure to plastic leachates, showing significant declines in photosynthetic efficiency, diversity, and abundance. Key heterotrophic taxa, such as SAR11, which are the most abundant planktonic organisms in the ocean, also exhibited significant declines in relative abundance when exposed to higher levels of PVC leachate. In contrast, many copiotrophic bacteria, including members of the Alteromonadales, dramatically increased in relative abundance under both exposure treatments. Moreover, functional gene and genome analyses, derived from metagenomes, revealed that PVC leachate exposure selects for fast-adapting, motile organisms, along with enrichment in genes usually associated with pathogenicity and an increased capacity to metabolize organic compounds leached from PVC.

CONCLUSIONS

This study shows that substances leached from plastics can restructure marine microbial communities with the potential for significant impacts on trophodynamics and biogeochemical cycling. These findings substantially expand our understanding of the ways by which plastic pollution impact life in our oceans, knowledge which is particularly important given that the burden of plastic pollution in the marine environment is predicted to continue to rise. Video Abstract.

Toward a long-term monitoring program for seawater plastic pollution in the north Pacific Ocean: Review and global comparison

Through a literature survey and meta-data analysis, monitoring methods and contamination levels of marine micro- and macroplastics in seawater were compared between the North Pacific and the world's other ocean basins. The minimum cut-off size in sampling and/or analysis of microplastics was crucial to the comparison of monitoring data. The North Pacific was most actively monitored for microplastics and showed comparatively high levels in the global context, while the Mediterranean Sea was most frequently monitored for macroplastics. Of the 65 extracted mean abundances of microplastics in seawater from the North Pacific, two (3.1%) exceeded the lowest predicted no-effect concentration (PNEC) proposed thus far. However, in the context of business-as-usual conditions, the PNEC exceedance probability may be expected to reach 27.7% in the North Pacific in 2100. The abundance of marine plastics in seawater, which reflects the current pollution status and marine organisms' waterborne exposure levels, is a useful indicator for marine plastic pollution. For regional and global assessments of pollution status across space and time, as well as assessment of ecological risk, two microplastic monitoring approaches are recommended along with their key aspects. Although microplastic pollution is closely linked with macroplastics, the monitoring data available for floating macroplastics and more extent to mesoplastics in most ocean basins are limited. A more specific framework for visual macroplastic survey (e.g. fixed minimum cut-off size, along with survey transect width and length according to survey vessel class) is required to facilitate data comparison. With the implementation of standardised methods, increased efforts are required to gather monitoring data for microplastics and-more importantly-floating macroplastics in seawater worldwide.

Structure and functional group regulation of plastics for efficient ammonia capture

Activated carbon and metal organic frameworks have been tested as NH₃ recovery adsorbents, however, they are limited due to low NH₃ adsorption capacity and high cost, respectively. In this study, ethylene glycol dimethacrylate (EGDMA) polymers as the representative ester plastics were tested, and their structure and adsorption sites were regulated using HNO₃, HCl, or H₂SO₄ with varied H⁺ concentrations. The results showed that the EGDMA polymers all used hydrolysis which promoted NH₃ adsorption via different mechanisms. With HNO₃ and HCl optimization, an increased surface area promoted NH₃ adsorption via physical forces. H₂SO₄ optimization resulted in -COOH, -OH, and -SO₃H formation, which reacted with NH₃ by chemical adsorption and hydrogen bonds. This significantly increased the NH₃ adsorption capacity (85.99 mg·g^-1) compared to the material before optimization (0.36 mg·g^-1). This study presents a novel low-cost and efficient method to recycle waste plastics as NH₃ adsorbents.

Biodegradation of Biodegradable Polymers in Mesophilic Aerobic Environments

Finding alternatives to diminish plastic pollution has become one of the main challenges of modern life. A few alternatives have gained potential for a shift toward a more circular and sustainable relationship with plastics. Biodegradable polymers derived from bio- and fossil-based sources have emerged as one feasible alternative to overcome inconveniences associated with the use and disposal of non-biodegradable polymers. The biodegradation process depends on the environment's factors, microorganisms and associated enzymes, and the polymer properties, resulting in a plethora of parameters that create a complex process whereby biodegradation times and rates can vary immensely. This review aims to provide a background and a comprehensive, systematic, and critical overview of this complex process with a special focus on the mesophilic range. Activity toward depolymerization by extracellular enzymes, biofilm effect on the dynamic of the degradation process, CO2 evolution evaluating the extent of biodegradation, and metabolic pathways are discussed. Remarks and perspectives for potential future research are provided with a focus on the current knowledge gaps if the goal is to minimize the persistence of plastics across environments. Innovative approaches such as the addition of specific compounds to trigger depolymerization under particular conditions, biostimulation, bioaugmentation, and the addition of natural and/or modified enzymes are state-of-the-art methods that need faster development. Furthermore, methods must be connected to standards and techniques that fully track the biodegradation process. More transdisciplinary research within areas of polymer chemistry/processing and microbiology/biochemistry is needed.

Biodegradable microplastics enhance soil microbial network complexity and ecological stochasticity

Biodegradable plastics have emerged as an ecological alternative to conventional petroleum-based plastics. Despite the recent advances in the effects of conventional microplastic on soil ecosystems, the ecological impact of biodegradable microplastics in soil environments remains poorly understood. Here, we performed soil microcosms with conventional (polyethylene and polystyrene) and biodegradable (polybutylene succinate and polylactic acid) microplastics to estimate their effects on the success patterns, co-occurrence networks, and the assembly mechanisms of soil bacterial communities. Biodegradable microplastics significantly altered the soil bacterial community composition with steeper temporal turnovers (rate: 0.317 - 0.514) compared to the conventional microplastic treatments (rate: 0.211 - 0.220). Network under biodegradable microplastics showed greater network complexity, including network size, connectivity, average clustering coefficient, and the number of keystone species, as compared with the conventional microplastic treatments. Additionally, the biodegradable microplastic network had higher robustness, which may be potentially due to the enhanced dissolved organic carbon contents in the soil treated with biodegradable microplastics. The bacterial community assembly was initially governed by deterministic homogeneous selection (93 - 100 %) under the stress of microplastics, but was progressively structured by increasing stochastic homogeneous dispersal (17.8 - 73.3 %) over time. The normalized stochasticity ratio also revealed that the application of microplastics increased the importance of stochastic processes following incubation. These findings greatly enhanced our understanding of the ecological mechanisms and interactions of soil bacterial communities in response to microplastic stress.