Journal of Environmental Sciences-china最新文献

Pretreatment of Low-Density Polyethylene (LDPE) with physicochemical methods before biodegradation has been demonstrated as an effective strategy. The pretreatment of LDPE exhibited alterations in molecular structure, reducing hydrophobicity and decreasing tensile strength. Additionally, pretreating LDPE enhanced microbial biodegradability to improve biofilm formation and significantly reduced the physical weight of LDPE film. AS3-8 consortia exhibited a maximum weight loss of 8.0 % ± 0.5 % after 45 days of incubation. While Bacillus sp. AS3 and Sphingobacterium sp. AS8 demonstrated LDPE weight loss of 5.03 % ± 1.6 % and 1.6 % ± 0.5 %, respectively. The structure of LDPE was altered after incubation with the bacterial strains, resulting in a reduction in the intensity of functional groups, including C=O, C=C, N-H, and C-N. The carbonyl index (CI) of LDPE also decreased by 7.17 % after the consortia AS3-8 degradation. Consortia AS3-8 significantly impacted the physical properties of LDPE by reducing the water contact angle (WCA), decreasing to 64.21° ± 3.69°, and tensile strength (TS), decreasing to 17.97 ± 0.3 MPa. Moreover, the esterase activity was measured through 45 days of incubation. SDS-PAGE analysis of the AS3-8 consortia revealed bands at 35, 48, and 70 kDa molecular weights, similar to known enzymes like laccase and esterase. Furthermore, SEM observations showed rough, cracked surfaces on pretreated LDPE, with biofilms present after incubation with the bacterial strains. GC-MS analysis revealed that AS3-8 consortia produced depolymerized chemicals, including alkanes, aldehydes, and esters. The LDPE biodegradation pathway was elucidated. This study addresses critical knowledge gaps in improving plastic degradation efficiency.

Rural domestic sewage treatment is critical for environmental protection. This study defines the spatial pattern of villages from the perspective of rural sewage treatment and develops an integrated decision-making system to propose a sewage treatment mode and scheme suitable for local conditions. By considering the village spatial layout and terrain factors, a decision tree model of residential density and terrain type was constructed with accuracies of 76.47 % and 96.00 %, respectively. Combined with binary classification probability unit regression, an appropriate sewage treatment mode for the village was determined with 87.00 % accuracy. The Analytic Hierarchy Process (AHP), combined with the Technique for Order Preference (TOPSIS) by Similarity to an Ideal Solution model, formed the basis for optimal treatment process selection under different emission standards. Verification was conducted in 542 villages across three counties of the Inner Mongolia Autonomous Region, focusing on the standard effluent effect (0.3773), low investment cost (0.3196), and high standard effluent effect (0.5115) to determine the best treatment process for the same emission standard under different needs. The annual environmental and carbon emission benefits of sewage treatment in these villages were estimated. This model matches village density, geographic feature, and social development level, and provides scientific support and a theoretical basis for rural sewage treatment decision-making.

To address the problems with catalytic degradation, such as poisoning and inactivation, a simple and efficient gas purging regeneration technique was developed for iron-based catalyst in-situ regeneration. Specifically, the effects of carrier gas types, regeneration temperatures, and granular activated carbon (GAC) addition on iron-based catalyst regeneration were investigated. The Fe₃O₄/γ-Al₂O₃ regenerated at 550 °C with additional GAC and 15 % water vapor exhibited the optimal degradation efficiency towards polychlorinated biphenyls (PCBs), with an increase from 41.2 % to 93.5 %, compared with non-regenerated Fe₃O₄/γ-Al₂O₃. In addition, the 60-hour stability test revealed a well-recovered catalytic activity. During the Fe₃O₄/γ-Al₂O₃ regeneration, the coke on the catalyst surface was oxidized and removed in the form of CO₂, and meanwhile the oxidized Fe(III) was reduced into Fe(II) in the catalyst. This study provides a safe and efficient iron-based catalyst regeneration technology for PCB off-gas degradation and reveals the catalytic activity recovery mechanism during catalyst regeneration.

The issue of microplastic (MPs) pollution has received increased attention in recent years. Studies have indicated that inhalation of microplastics may result in the cardiovascular harm. However, the specific mechanism remains to be elucidated. In this study, 5 µm polystyrene microplastics (PS-MPs) were employed to construct in vivo and in vitro exposure models to investigate the potential mechanisms of microplastic-induced cardiac fibrosis. In vivo model of respiratory exposure to MPs, echocardiography observed a decrease in systolic-diastolic function of the mouse heart, and myocardial tissue showed significant mitochondrial morphological abnormalities and myocardial fibrosis. In vitro models also revealed upregulation of fibrosis indicators in human cardiomyocytes AC16 cells. Transcriptome and RT-qPCR assay exposed that ferroptosis-related pathways were significantly gathered in the MPs group, with decreased expression of ferroptosis related genes SLC7A11 and GPX4. Liproxstatin-1 (Lip-1), a ferroptosis inhibitor, significantly ameliorated MPs-induced cardiomyocyte fibrosis and ferroptosis. We further demonstrated that inhibition of hypoxia-inducible factor α (HIF-α) and oxidative stress ameliorated PS-MPs-induced cardiomyocyte ferroptosis, and thus upregulation of the HIF pathway and oxidative stress may be the upstream mechanism of MPs-induced ferroptosis in myocardial fibrosis. Above all, our study demonstrated that MPs exposure resulted in cardiac fibrosis via the HIF-ROS-SLC7A11/GPX4 signaling pathway.