Environmental Science: Processes & Impacts最新文献

The widespread use of plastics and their improper disposal have released a large number of micro- and nano-plastics (MNPs) into various environmental media. Although the release of MNPs from individual plastic products has been widely reported, there is a lack of a holistic assessment framework to determine the overall release of plastic products to soil, water, and air during their life cycle. Therefore, based on big data, neural network algorithms, and material flows, a new open platform for the comprehensive assessment of the release of MNPs from plastic products will be developed. The proposed emission inventory platform consists of three main modules: a global polymer product production dataset, an assessment of the emission processes, influencing factors, and emission factors of MNPs, and an emission inventory of MNP releases to the environment. The global data on polymer production, use, and waste disposal, and collate data on the degradation behavior of different plastic types under various environmental conditions will be collected. Next, big data analysis will be applied to train the patterns of MNP production and emissions, and algorithms such as neural networks will be used to simulate the complex processes and mechanisms of MNP emissions. Finally, a comprehensive emission inventory model will be established. The proposed dynamic MNPs emission assessment platform integrates material flow analysis and experimentally validated release kinetics. Utilizing machine learning techniques and laboratory and field datasets, the platform can derive dynamic, environment-specific emission factors to support specific emission estimates, source prioritization, and targeted emission reduction strategies.

As compelling evidence of global warming, heatwaves are expected to elevate O₃ mixing ratios in highly polluted urban areas. In summer 2018, Seoul, an Asian megacity, experienced elevated O₃ levels in conjunction with a temperature surge (maximum of 38.9 °C). This study quantitatively estimates the O₃-climate penalty through measurements of nitrogen oxide species, volatile organic compounds (VOCs), and the boundary-layer height, as well as model simulations. The results highlight an acceleration of O₃ concentration increment with increased temperature and elevated ozone production efficiency in NO_x-saturated conditions. Furthermore, it emphasizes the importance of dynamic boundary-layer processes and increased VOC concentrations resulting from fugitive emissions during the heatwave.

Brown carbon (BrC) plays a crucial role in altering radiative forcing and impacting human health. However, comprehensive knowledge of BrC in megacities remains limited. This study systematically examined the optical properties, oxidative potential (OP) and chemical composition of BrC in the megacity Shenyang of Northeast China. Methanol-soluble BrC (MSBrC) and humic-like substances (HULIS) were the most important components of total BrC and water-soluble BrC (WSBrC), respectively. For different BrC fractions, the mass absorption efficiency at 365 nm (MAE₃₆₅) varied in the range of 0.16-0.96 m² g^-1, and the absorption Ångström exponent (AAE) ranged from 4.25 to 12.10, which were dependent on the chemical composition of BrC. The contribution of polycyclic aromatic hydrocarbons (PAHs) and their derivatives to the MSBrC light absorption was up to 2.93%. Water-insoluble BrC (WISBrC) showed a relatively higher OP value, which can be largely related to the content of C-H groups with strong electron transfer capacity.

Nanoplastics, typically smaller than thousand nanometers, originate from the degradation of plastic waste and pose significant threat to aquatic ecosystems by acting both as pollutants and as carriers for harmful contaminants. Understanding their colloidal behavior in aquatic environments is therefore critical. Unlike previous studies that used synthetic particles, this research examines nanoplastics generated from real-world plastic waste, providing a realistic representation of their environmental behavior. Polyethylene terephthalate (PET) and polystyrene (PS) nanoplastics, sourced from discarded water bottles and packaging, were synthesized (∼464 nm for PET; ∼483 nm for PS) and characterized using DLS, SEM, FTIR, and Raman spectroscopy. Aggregation behavior was evaluated via time-resolved DLS in NaCl and MgCl₂ solutions, revealing critical coagulation concentrations (CCCs) of 44.50 mM NaCl and 2.17 mM MgCl₂ for PET, and 33.82 mM NaCl and 2.21 mM MgCl₂ for PS. Aggregation was faster in the presence of divalent Mg²⁺ compared to monovalent Na⁺, and PS exhibited lower CCC values than PET, attributed to differences in hydrophobicity and surface chemistry. As predicted by Derjaguin-Landau-Verwey-Overbeek (DLVO) theory, the nanoplastics would remain stable in freshwater but would aggregate rapidly in saline environments. This dependence on electrolyte concentration indicates potentially enhanced mobility and persistence in rivers and lakes, while promoting sedimentation and pollutant accumulation in estuarine and marine systems. These shifts in aggregation behavior in aquatic environments have direct implications for nanoplastic transport pathways, ecological exposure, and long-term environmental risks.

Characterized by the small size and extensive distribution, micro green spaces are vital for urban environmental quality and resident well-being. Yet, they are increasingly recognized as hotspots for the convergence of antibiotic resistance genes (ARGs); systematic research on ARG pollution in these areas remains limited. This study investigated the distribution and sources of ARGs in soils from 21 micro green spaces in Tianjin, China. The results indicated a high prevalence of ARGs, with a predominance of aminoglycoside, β-lactam, fluoroquinolone and multidrug resistance genes. Their dissemination was primarily facilitated by protection mechanisms and horizontal gene transfer (HGT) mediated by mobile genetic elements (MGEs). Source analysis indicated that in intra-urban areas, ARGs were mainly contributed by trash (46.9%), followed by irrigation water (37.3%) and pet/bird feces (15.8%). In extra-urban areas, irrigation water was the dominant source (72.8%), demonstrating considerable spatial heterogeneity. Mechanistic analysis revealed soil total phosphorus (TP) as the strongest driver of ARG enrichment (p < 0.001). Furthermore, specific phyla like Cloacimonadota and Myxococcota were linked to ARG diffusion through their correlation with MGEs. This study fills a key knowledge gap on ARGs in micro green spaces, providing a scientific basis for interventions aimed at safeguarding urban ecological security and public health.

Microplastics (MPs) present widespread and persistent threats to terrestrial ecosystems by compromising ecosystem integrity, contaminating food webs, and posing significant risks to human health. This review systematically discusses the current knowledge on MPs resulting from legacy waste and landfills in India. Spatio-temporal dynamics and matrix-wise occurrence of MPs across landfill leachate, soils, sediments, compost, and air are presented. The literature indicates that MP migration is influenced by seasonal hydrology, atmospheric deposition, landfill leachate infiltration, and agricultural amendments, leading to their complex vertical and lateral distributions. Various studies indicate that MPs belong to diverse polymer types, predominantly polyethylene (PE), polypropylene (PP), and polyethylene terephthalate (PET), with fibers and fragments as the most common morphologies of MPs. The widespread presence of MPs in various matrices further highlights the under-explored pathways of terrestrial contamination and potential food chain transfer. Despite policy advancements through frameworks such as the Plastic Waste Management Rules and Swachh Bharat Mission-Urban 2.0, the integration of MPs monitoring and mitigation into national waste and soil health guidelines is still evolving. There remains an opportunity to generate comprehensive long-term field data, establish specific standardized protocols, and fully incorporate MPs considerations into remediation and circular economy initiatives. This review signifies the importance of transdisciplinary research, improved technological interventions, and targeted policy actions to address MPs contamination in India's terrestrial ecosystems. The findings aim to inform decision-makers and researchers in developing robust, context-sensitive strategies to mitigate MPs pollution, safeguard environmental quality, and protect public health.

Pyrene belongs to the highly toxic class of polycyclic aromatic hydrocarbons and has carcinogenic properties; thus, the kinetics of its OH-initiated oxidation is theoretically investigated in a wide range of conditions (T = 200-2000 K and P = 7.6-76,000 Torr). The T & P-dependent kinetic behaviors were studied within the stochastic RRKM-based master equation framework with the potential energy profile constructed at the ROCBS-QB3//M06-2X/aug-cc-pVTZ level. The computed total rate constants k_total are in good agreement with the laboratory values, thus helping resolve the discrepancy between the prior calculations and the measured values. The model reveals detailed mechanistic insights: (i) the OH-addition channels from the Cα and Cγ atoms of pyrene (to form the adducts 5-hydroxy-4,5-dihydropyren-4-yl (I1) and 1-hydroxy-1H-pyren-10a-yl (I2)) predominate under atmospheric conditions, while the direct H-abstraction pathways become dominating at T > 500 K; (ii) the U-shaped T-dependent behaviors of k_total and its slightly positive P-dependence at low T (e.g., T ≤ 500 K and P = 760 Torr) are due to the T-dependent mechanism shift. Additionally, pyrene should not be considered a persistent organic pollutant (POP) due to its short calculated atmospheric lifetime (∼4.1 hours toward OH), which is significantly shorter than those resulting from degradation by other abundant oxidants (i.e., Cl, NO₃, and O₃) present in the atmosphere. Moreover, pyren-4-ol (and pyrene-4,5-dione) and pyren-1-ol (and pyrene-1,2-dione) are suggested as the primary products of I1 and I2, respectively, when further oxidized by O₂/NO. The results reveal that both short and long-term pyrene exposure is highly toxic to aquatic organisms; while its main degradation products, namely, I1 and I2, show lower toxicity, they still pose a significant threat to marine organisms and the ecosystem.

The long-term positioning test for biochar for saline-alkali land improvement was carried out for four treatments, CK (0%), and 20 (C1), 40 (C2) and 60 (C3) t ha^-1, to clarify the characteristics of the organic carbon components and the carbon sequestration potential. Compared to the control sample, the soil water holding capacity was significantly increased by 35.6-39.2% when biochar was applied. The average data from a ten-year field study demonstrated that biochar incorporation significantly increased the total soil organic carbon (TOC) by 11.2-54.4%. The amounts of dissolved organic carbon in the soil (DOC), easily oxidizable carbon (EOC), and mineral-bound organic carbon (MOC) were the highest in the 0-20 cm layer and then decreased with increasing soil depth with ranges of change of -11.3-61.8, 29.6-186.7 and -20.6-105.3%. In addition, the concentrations increased with increasing biochar addition rates, and the DOC, EOC, and MOC were significantly more positive than the TOC. In general, the ten-year application of biochar in saline-alkali soil considerably increased the soil organic carbon and carbon component content, which was conducive to improving the soil carbon sequestration capacity and the stability of the soil carbon pool. The biochar improved the saline-alkali soil with long term effects, which could increase soil carbon fixation and help emission reduction in the future.

Extracellular reductive dechlorination of chlorinated aliphatic hydrocarbons (CAHs) by non-electroactive bacteria is rarely investigated. In this study, we demonstrated that common bacteria Gram-positive Bacillus subtilis (B. subtilis) and Gram-negative Escherichia coli (E. coli) in aqueous suspensions (1.2 × 10⁸ cells per mL) could dechlorinate a model CAH compound hexachloroethane (HCE, initial 40 µmol L^-1) at ratios of 83.7% and 54.1% respectively to pentachloroethane (PCE) and tetrachloroethylene (TCE) after 56 h incubation at pH 7.0 and 30 °C. The majority of the parent compound (HCE) and reaction products (PCE and TCE) present in the extracellular matrix indicated the predominance of extracellular reduction. Removing EPS from bacteria suppressed HCE reduction, while adding extra dissolved EPS slightly enhanced HCE reduction. The enhanced reduction of HCE by low-molecular-weight EPS (<3 kDa) relative to bulk EPS of B. subtilis and its counterpart high-molecular-weight EPS (>3 kDa) indicated that low-molecular-weight EPS were more enriched in active reducing agents. Additionally, dechlorination of HCE by electrochemically reduced glutathione and disodium anthraquinone-2,6-disulfonate or juglone suggested that thiol groups and quinones were involved as reducing agents and electron mediators, respectively. These findings underscore a previously unknown process of extracellular reductive dechlorination of CAHs by common non-electroactive bacteria and the key role played by EPS.

Bioplastics are widely promoted as environmentally safer alternatives to conventional polymers; however, their ecotoxicological implications across trophic levels remain poorly understood. In terrestrial detritivore networks, where trophic interactions involve decomposers and necrophagous insects, the ingestion and transfer of microplastics (MPs) derived from bioplastics may induce systemic dysfunctions in organisms with key ecological functions. Here, we investigated the trophic transfer and physiological impacts of polylactic acid microplastics (PLA-MPs) in a simulated terrestrial food chain, from Chrysomya megacephala to Tribolium castaneum. We hypothesized that PLA-MPs would be retained across metamorphosis and transferred between trophic levels, inducing multisystemic effects in secondary consumers. Our findings confirm the transstadial retention of PLA-MPs in C. megacephala and their effective trophic transfer to T. castaneum. Despite a reduction in MP burden across trophic transitions, exposed beetles exhibited behavioral alterations, including hyperactivity and spatial disorganization, alongside decreased levels of serotonin, dopamine, and acetylcholinesterase activity. These neurofunctional impairments were accompanied by redox imbalance, collapse of digestive enzyme activities (including chymotrypsin, trypsin, and alkaline phosphatase), and reduced biomass, despite elevated levels of total proteins, triglycerides, and carbohydrates. Network analysis revealed a systemic reorganization, characterized by the loss of central physiological hubs and the emergence of stress-related biomarkers. Random forest modeling identified nine key variables spanning neurochemical, oxidative, and digestive axes as robust predictors of internal PLA-MP burden. This study provides the first evidence that PLA-MPs can be effectively transferred through a terrestrial detritivore chain via necrophagy, inducing multisystemic physiological disruptions in secondary consumers. Thus, our findings expand current bioplastic risk assessment paradigms by advocating the integration of systemic biomarkers, trophic dynamics, and underexplored exposure pathways in terrestrial scenarios.