Environmental Chemistry Letters最新文献

Substantial amounts of microplastics are ingested by living organisms, in particular by humans; yet, the fate of microplastics through digestion is poorly known. Here, we administrated 1–2 mm polystyrene microplastics to quails to monitor their dynamics of fecal excretion. We quantified small-sized polystyrene microplastics, lower than 500 µm, by pyrolysis-assisted thermal desorption gas chromatography-mass spectrometry. The surface morphology of parent microplastics was also characterized. Results show that 90 wt% of parent particles were excreted within 10 days, mostly in the first 24 h, whereas fragmented microplastics persisted for up to 20-day post-ingestion. Aged polystyrene and sand co-administered particles exhibited greater fragmentation than those in other groups. Parent microplastics were significantly oxidized after digestion.

Cooking with polytetrafluoroethylene-coated pans releases thousands to millions of microplastic and nanoplastic particles per use, directly contaminating food and the environment. Here we review polytetrafluoroethylene microplastics with emphasis on polytetrafluoroethylene characteristics, environmental occurrence, and detection methods. Polytetrafluoroethylene has high chemical stability and is used in medical devices, clothes and protective suits, aerospace, non-sticking pans, cables and insulation, filtration, irrigation and electronics. We discuss plastic utensils as microplastic sources, and the influence of temperature and aging on microplastic release. The presence of microplastics in humans, wild animals, sediments, water and the atmosphere is described. Limitations of actual analytical methods such as density separation are detailed. Polytetrafluoroethylene accounts for about 60% of the global fluoropolymer market, and is a major contributor to microplastic pollution, accounting for up to 44% of microplastics in sediments, 74% in benthic fish, and 60% in human organs. Our meta-analysis shows that polytetrafluoroethylene microplastic concentrations average 7.3 ± 13.3 particles per L in water, 3,685.7 ± 4,832.0 particles per kg in sediment, 24.9 ± 37.1 particles per individual in fish, and 482.5 ± 554.1 particles per kg in human tissues. Polytetrafluoroethylene microplastics may impair physiological homeostasis by inducing oxidative stress, inflammation, necrosis, and disruption of key cellular signaling pathways.

Health impact of atmospheric particulate matter is traditionally assessed using mass concentrations of particulate matter, yet epidemiological findings reveal inconsistencies, and respiratory and cardiovascular diseases often correlate more strongly with the oxidative potential of particulate matter, which reflects its ability to generate reactive oxygen species and induce oxidative stress. Here we review the oxidative potential of particulate matter in more than 200 field studies, with focus on epidemiological evidence, methods, influencing factors, and the contribution of the emission sources. Methods to assess the oxidative potential include electron spin resonance, the dithiothreitol and dichlorofluorescein assays, antioxidant depletion, and hydroxyl radical production. Major influencing factors comprise particle size and the presence of metals and carbonaceous aerosols. We observed that the oxidative potential varies substantially depending on particle size, the presence of transition metals and quinones, and emission sources such as biomass burning and traffic. Existing assays vary in their sensitivity to specific components of particulate matter, making comparisons between studies challenging. Methodological decisions such as the choice of extraction solvents and filter types can significantly change the measured oxidative potential. Overall, there is a need for standardized protocols and longitudinal studies linking oxidative potential to health outcomes.

Halogenated organic compounds are widely occurring persistent pollutants originating from herbicides, insecticides, and other industrial products, calling for advanced methods of environmental remediation. Here, we review the microbial processes allowing to remove the halogen atoms, namely, fluorine, bromine, and chlorine, from the pollutants. We discuss the fate of halogenated organic compounds, the microbial halogen cycle, bacterial dehalogenases, and the mechanisms of dehalogenation, metagenomics, and genetic modifications. Bacterial dehalogenases include hydrolytic, reductive, oxidative, and glutathione-dependent dehalogenases. Dehalogenation mechanisms comprise hydrolytic, reductive, and oxygenolytic dehalogenation.

Global warming, pollution, and industrial agriculture are degrading soils worldwide and threatening food security, thus calling for advanced methods to improve soil quality and fertility, and to sequester carbon. Here, we review the use of artificial humus with focus on the synthesis of artificial humus by hydrothermal carbonization of biomass. We detail the reaction mechanism, parameters controlling the reaction, differences between artificial and natural humus, laboratory and industrial production, biomass components, effects on soil nutrients and microbial biomass, remediation of saline-alkali land, and life cycle assessment. After reaction at 150–230 °C, the conversion rate is high, and the properties of artificial humus are very similar to those of natural humus. The application of this artificial humus improves soil nutrient availability, saline-alkali land, microbial characteristics, and the overall soil health. In saline-alkali soils, the application of artificial humus increases the cation exchange capacity up to 1.78 times, with a short-term pH decrease of 0.26–1.0 and an electrical conductivity decrease of 37–60 µS·cm⁻¹. Nevertheless, large-scale application of this technology still faces challenges such as high equipment investment costs, fluctuations in product characteristics between batches, and the lack of unified quality assessment standards.

Antimicrobial resistance is a major health issue that rapidly decreases the number of marketed chemical antibiotics that can cure microbial diseases, calling for alternative solutions. Here we review bacteriophage therapy using nanotechnological delivery with focus on definition and classification, dry powder formation, liposome encapsulation of bacteriophages, hydrogels, electrospinning of phages into nanofibers, and phage emulsions. Dry powder can be done by spray drying and lyophilization. Hydrogels include alginate, polyethylene glycol, polyvinyl glycol, nanocellulose, agarose, hyaluronan and poloxamer. We observed that bacteriophage therapy displays advantages such as self-replicating properties, and minimal disruption to the host microbiota. Recently developed lipid-based nanocarriers, hydrogels, and electrospun core–shell nanofibers have improved phage protection under harsh physiological conditions. Encapsulation using microfluidics-derived nanoemulsions and natural polymers allows for controlled, site-specific phage release and enhanced biofilm penetration. Surface modification using biomimetic coatings and biodegradable materials reduces immunogenicity and extends systemic circulation. Limitations of bacteriophage therapy comprise poor phage stability in physiological conditions, rapid removal by the immune system, limited penetration into biofilms, and the absence of standardized, scalable delivery systems. Clinical studies often focus solely on bacterial reduction while overlooking formulation integrity, delivery efficiency, and pharmacokinetics.