Total organic carbon content as an index to estimate the sorption capacity of micro- and nano-plastics for hydrophobic organic contaminants

Aging behavior and leaching characteristics of microfibers in landfill leachate: Important role of surface mesh structure

Mesh-structured films formed by the post-processing of microfibers improves their permeability and dexterity, such as disposable masks. However, the aging behavior and potential risks of mesh-structured microfibers (MS-MFs) in landfill leachate remain poorly understood. Herein, the aging behavior and mechanisms of MS-MFs and ordinary polypropylene-films (PP-films) microplastics, as well as their leaching concerning dissolved organic matter (DOM) in landfill leachate were investigated. Results revealed that MS-MFs underwent more significant physicochemical changes than PP-films during the aging process in landfill leachate, due to their rich porous habitats. An important factor in the photoaging of MS-MFs was related to reactive oxygen species produced by DOM, and this process was promoted by photoelectrons under UV irradiation. Compared with PP-films, MS-MFs released more DOM and nano-plastics fragments into landfill leachate, altering the composition and molecular weight of DOM. Aged MS-MFs-DOM generated new components, and humus-like substances produced by photochemistry showed the largest increase. Correlation analysis revealed that leached DOM was positively correlated with oxygen-containing groups accumulated in aged MS-MFs. Overall, MS-MFs will bring higher environmental risks and become a new long-term source of DOM contaminants in landfill leachate. This study provides new insights into the impact of novel microfibers on landfill leachate carbon dynamics.

Sustainable use of plastic-derived nanocarbons as a promising larvicidal and growth inhibitor agent towards control of mosquitoes

Nanoscale carbon was obtained from six widely used plastics (PET, HDPE, PVC, LDPE, PP and PP) via thermal degradation (600 °C) under inert atmosphere. The thermally degraded products were processed through bath sonication followed by lyophilisation and the same was characterized through proximate analysis, UV-Vis spectroscopy, Scanning electron micrograph (SEM) with energy dispersive X-ray (EDX) analysis, Transmission electron micrograph (TEM), Dynamic light scattering (DLS) and Fourier transform infrared spectroscopy (FTIR). A series of aqueous solution of nanoscale carbon (5-30 mg/L) were prepared and same were used as both mosquito growth inhibitor and larvicidal agent against 3rd and 4th instar larvae of Culex pipiens. The significant percent mortality results were recorded for LDPE (p < 0.007) with average particle size of 3.01 nm and 62.95 W% of carbon and PS (p < 0.002) with average particle size of 12.80 nm and 58.73 W% of carbon against 3rd instar larvae, respectively. Similarly, for 4th instar larvae, both significant pupicidal and adulticidal activity were also recorded for PET (F = 24.0, p < 0.0001 and F = 5.73, p < 0.006), and HDPE (F = 26.0, p < 0.0001) and F = 5.30, p < 0.008). However, significant pupicidal activity were observed for PVC (F = 6.90, p < 0.003), and PS (F = 21.30, p < 0.0001). Histological, bio-chemical and microscopic studies were revealed that nanoscale carbon causes mild to severe damage of external and internal cellular integrity of larvae. However, nanoscale carbon does not exhibit any chromosomal abnormality and anatomical irregularities in Allium cepa and Cicer arietinum, respectively. Similarly, non-significant results with respect to blood cell deformation were also recorded from blood smear of Poecilia reticulata. Therefore, it can be concluded that plastic origin nanoscale carbon could be a viable sustainable nano-weapon towards control of insects.

Detection of nanoplastics released from consumer plastic food containers by electromagnetic heating pyrolysis mass spectrometry

Nanoplastics released from consumer plastic food containers are emerging environmental pollutants and directly ingested as part of the diet. However, quantification methods for nanoplastics are still lacking. Herein, a rapid identification and mass quantification approach was developed for nanoplastics analysis by combining electromagnetic heating with pyrolysis mass spectrometry (Eh-Py-MS). The pyrolysis products directly entered into the MS, which omits the gas phase separation process and shortens the detection time. A compact pyrolysis chamber was used and this increased the sample transfer efficiency and lowered power requirement. The operational parameters were systematically examined. The influence of nanoplastic size, additive, humic acid, and aging on detection was investigated, and it was concluded that environmental factors (humic acid, aging) and plastic properties (size, additives) did not influence the detection. The developed chamber showed that the limit of detection of polystyrene (PS) nanoplastics was 15.72 ng. Several typical food packages were demonstrated with satisfactory recovery rates (87.5-110%) and precision (RSD ≤11.36%). These results suggested that the consumer plastic food containers are a significant source of direct exposure to nanoplastics in humans from the environment.

Aging of plastics in aquatic environments: Pathways, environmental behavior, ecological impacts, analyses and quantifications

The ubiquity of plastics in our environment has brought about pressing concerns, with their aging processes, photo-oxidation, mechanical abrasion, and biodegradation, being at the forefront. Microplastics (MPs), whether originating from plastic degradation or direct anthropogenic sources, further complicate this landscape. This review delves into the intricate aging dynamics of plastics in aquatic environments under various influential factors. We discuss the physicochemical changes that occur in aged plastics and the release of oxidation products during their degradation. Particular attention is given to their evolving environmental interactions and the resulting ecotoxicological implications. A rigorous evaluation is also conducted for methodologies in the analysis and quantification of plastics aging, identifying their merits and limitations and suggesting potential avenues for future research. This comprehensive review is able to illuminate the complexities of plastics aging, charting a path for future research and aiding in the formulation of informed policy decisions.

Characterization and source apportionment of microplastics in Indian composts

Microplastics (MP), small plastic particles under 5 mm, are pollutants known to carry heavy metals in ecosystems. Composts are a significant source of soil microplastics. This study examined MSW composts from Kochi and Kozhikode in India for microplastic concentrations and heavy metals' accumulation thereon. Microplastics were isolated using zinc chloride density separation, with Fenton's reagent used for organic matter oxidation. Resin types were identified using FTIR analysis that showed the presence of PE, PP, PS, nylon, PET, and allyl alcohol copolymer. In Kozhikode's compost, the average concentration of microplastics was 840 ± 30 items/kg, while Kochi had 1600 ± 111 items/kg, mainly polyethylene films. PE was the most prevalent resin, comprising 58.3% in Kozhikode and 73.37% in Kochi. Heavy metal analysis of MP showed significant concentrations of lead, cadmium, zinc, copper, and manganese adsorbed on the surface of microplastics. The concentrations of heavy metals in the MP before Fenton oxidation ranged from 1.02 to 2.02 times the corresponding concentrations in compost for Kozhikode and 1.23 to 2.85 times for Kochi. Source apportionment studies revealed that 64% of microplastics in Kozhikode and 77% in Kochi originated from single-use plastics. Ecological risk indices, PLI and PHI, showed that composts from both locations fall under hazard level V. The study revealed that compost from unsegregated MSW can act as a significant source of microplastics and heavy metals in the soil environment, with single-use plastics contributing major share of the issue.

Elucidating the characteristic of leachates released from microplastics under different aging conditions: Perspectives of dissolved organic carbon fingerprints and nano-plastics

Despite numerous studies that have been devoted to investigating the aging behaviors of microplastics (MPs), dissolved organic carbon (DOC) and nano-plastics (NPs) released from MPs under different aging conditions were limited. Herein, the characterizations and underlying mechanisms of DOC and NPs leaching from MPs (PVC and PS) in the aquatic environment for 130 days under different aging conditions were investigated. The results showed that aging could reduce the abundance of MPs, and high temperature and UV aging generated small-sized MPs (< 100 μm), especially UV aging. DOC-releasing characteristics were related to MP type and aging condition. Meanwhile, MPs were prone to release protein-like and hydrophilic substances except for 60 °C aging of PS MPs. Additionally, 8.77 × 10⁹-8.87 × 10¹⁰ and 4.06 × 10⁹-3.94 × 10¹⁰ NPs/L were detected in leachates from PVC and PS MPs-aged treatments, respectively. High temperature and UV promoted the release of NPs, especially UV irradiation. Meanwhile, smaller sizes and rougher NPs were observed in UV-aged treatments, implying higher ecological risks of leachates from MPs under UV aging. This study highlights the leachate released from MPs under different aging conditions comprehensively, which could offset the knowledge gap between the MPs' aging and their potential threats.