Journal of environmental sciences最新文献

Hydrothermal stability is crucial for the practical application of deNO_x catalyst on diesel vehicles, for the selective catalytic reduction of NO_x with NH₃ (NH₃-SCR). SnO₂-based materials possess superior hydrothermal stability, which is attractive for the development of NH₃-SCR catalyst. In this work, a series of Ce-Nb/SnO₂ catalysts, with Ce and Nb loading on SnO₂ support, were prepared by impregnation method. It was found that, the NH₃-SCR activities and hydrothermal stabilities of the Ce-Nb/SnO₂ catalysts significantly varied with the impregnation sequences, and the Ce-Nb(f)/SnO₂ catalyst that firstly impregnated Nb and then impregnated Ce exhibited the best performance. The characterization results revealed that Ce-Nb(f)/SnO₂ possessed appropriate acidity and redox capability. Furthermore, the strong synergistic effect between Nb and Sn species stabilized the structure and maintained the dispersion of acid sites. This study may provide a new understanding for the effect of impregnation sequence on activity and hydrothermal stability and a new environmental-friendly NH₃-SCR catalyst with potential applications for NO_x removal from diesel and hydrogen-fueled engines.

Bi₂O₂CO₃(BOC)/Bi₄O₅Br₂(BOB)/reduced graphene oxide (rGO) Z-scheme heterojunction with promising photocatalytic properties was synthesized via a facile one-pot room-temperature method. Ultra-thin nanosheets of BOC and BOB were grown in situ on rGO. The formed 2D/2D direct Z-scheme heterojunction of BOC/BOB with oxygen vacancies (OVs) effectively leads to lower negative electron reduction potential of BOB as well as higher positive hole oxidation potential of BOC, showing improved reduction/oxidation ability. Particularly, rGO is an acceptor of the electrons from the conduction band of BOC. Its dual roles significantly improve the transfer performance of photo-induced charge carriers and accelerate their separation. With layered nanosheet structure, rich OVs, high specific surface area, and increased utilization efficiency of visible light, the multiple synergistic effects of BOC/BOB/rGO can achieve effective generation and separation of the electron-holes, thereby generating more •O₂⁻ and h⁺. The photocatalytic reduction efficiency of CO₂ to CO (12.91 µmol/(g*hr)) is three times higher than that of BOC (4.18 µmol/(g*hr)). Moreover, it also achieved almost 100% removal of Rhodamine B and cyanobacterial cells within 2 hours.

Anaerobic digestion (AD) of waste activated sludge (WAS) is usually limited by the low generation efficiency of methane. Fe(III)-loaded chitosan composite (CTS-Fe) have been reported to effectively enhanced the digestion of WAS, but its role in promoting anaerobic sludge digestion remains unclear. In present study, the effects of CTS-Fe on the hydrolysis and methanogenesis stages of WAS anaerobic digestion were investigated. The addition of CTS-Fe increased methane production potential by 8%–23% under the tested conditions with the addition of 5–20 g/L CTS-Fe. Besides, the results demonstrate that the addition of CTS-Fe could effectively promote the hydrolysis of WAS, evidenced by lower protein or polysaccharides concentration, higher soluble organic carbon in rector adding CTS-Fe, as well as the increased activity of extracellular hydrolase with higher CTS-Fe concentration. Meanwhile, the enrichment of Clostridia abundance (iron-reducing bacteria (IRBs)) was observed in CTS-Fe adding reactor (8.9%–13.8%), which was higher than that in the control reactor (7.9%). The observation further suggesting the acceleration of hydrolysis through dissimilatory iron reduction (DIR) process, thus providing abundant substrates for methanogenesis. However, the presence of CTS-Fe was inhibited the acetoclastic and hydrogenotrophic methanogenesis process, which could be ascribed to the Fe(III) act as electron acceptor coupled to methane for anaerobic oxidation. Furthermore, coenzyme F420 activity in the CTS-Fe added reactor was 34.9% lower than in the blank, also abundance of microorganisms involved in hydrogenotrophic methanogenesis was decreased. Results from this study could provide theoretical support for the practical applications of CTS-Fe.

Observation-based method for O₃ formation sensitivity research is an important tool to analyze the causes of ground-level O₃ pollution, which has broad application potentials in determining the O₃ pollution formation mechanism and developing prevention and control strategies. This paper outlined the development history of research on O₃ formation sensitivity based on observational methods, described the principle and applicability of the methodology, summarized the relative application results in China and provided recommendations on the prevention and control of O₃ pollution in China based on relevant study results, and finally pointed out the shortcomings and future development prospects in this field in China. The overview study showed that the O₃ formation sensitivity in some urban areas in China in recent years presented a gradual shifting tendency from the VOC-limited regime to the transition regime or the NO_x-limited regime due to the implementation of the O₃ precursors emission reduction policies; O₃ pollution control strategies and precursor control countermeasures should be formulated based on local conditions and the dynamic control capability of O₃ pollution control measures should be improved. There are still some current deficiencies in the study field in China. Therefore, it is recommended that a stereoscopic monitoring network for atmospheric photochemical components should be further constructed and improved; the atmospheric chemical mechanisms should be vigorously developed, and standardized methods for determining the O₃ formation sensitivity should be established in China in the near future.

Peroxyacetyl nitrate (PAN) is an important photochemical pollutant in the troposphere, whereas long-term measurements are scarce in rural areas in North China Plain (NCP), resulting in unclear seasonal variations and sources of PAN in rural NCP. In this study, we conducted a 1-year observation of PAN during 2021-2022 at the rural NCP site. The average concentrations of PAN were 1.10, 0.75, 0.65, and 0.88 ppbv in spring, summer, autumn, and winter, respectively, with a 1-year average of 0.81 ± 0.60 ppbv. Calculations indicate that the loss of PAN through thermal decomposition in summer accounts for 43.2% of the total formed PAN, which is an important reason for the low concentration of PAN in summer. We speculate that since the correlation between PAN and O₃ in winter is significantly lower than that in other seasons, the observed regional transport of PAN cannot be ignored in winter. Through budget analysis, regional transport accounted for 12.8% and 55.9% of the observed PAN on the spring and winter pollution days, respectively, which showed that regional transport played key roles during the photochemical pollution of the rural NCP in winter. The potential source contribution function revealed that the transported PAN mainly comes from southern Hebei in spring. In winter, the transported PAN was mainly from Langfang, Hengshui, and southern Beijing. Our findings may aid in understanding PAN variations in different seasons in rural areas and highlight the impact of regional transport on the PAN budget.

As a vital type of light-absorbing aerosol, brown carbon (BrC) presents inherent associations with atmospheric photochemistry and climate change. However, the understanding of the chemical and optical properties of BrC is limited, especially in some resource-dependent cities with long heating periods in northwest China. This study showed that the annual average abundances of Water-soluble BrC (WS-BrC) were 9.33±7.42 and 8.69±6.29 µg/m³ in Baotou and Wuhai and the concentrations, absorption coefficient (Abs₃₆₅), and mass absorption efficiency (MAE₃₆₅) of WS-BrC presented significant seasonal patterns, with high values in the heating season and low values in the non-heating season; while showing opposite seasonal trends for the Absorption Ångström exponent (AAE_300-400). Comparatively, the levels of WS-BrC in developing regions (such as cities in Asia) were higher than those in developed regions (such as cities in Europe and Australia), indicating the significant differences in energy consumption in these regions. By combining fluorescence excitation-emission matrix (EEM) spectra with the parallel factor (PARAFAC) model, humic-like (C1 and C2) and protein-like (C3) substances were identified, and accounted for 61.40%±4.66% and 38.6%±3.78% at Baotou, and 60.33%±6.29% and 39.67%±4.17% at Wuhai, respectively. The results of source apportionment suggested that the potential source regions of WS-BrC varied in heating vs. non-heating seasons and that the properties of WS-BrC significantly depended on primary emissions (e.g., combustion emissions) and secondary formation.

Lipid metabolism play an essential role in occurrence and development of asthma, and it can be disturbed by phthalate esters (PAEs) and organophosphate flame retardants (OPFRs). As a chronic inflammatory respiratory disease, the occurrence risk of childhood asthma is increased by PAEs and OPFRs exposure, but it remains not entirely clear how PAEs and OPFRs contribute the onset and progress of the disease. We have profiled the serum levels of PAEs and OPFRs congeners by liquid chromatography coupled with mass spectrometry, and its relationships with the dysregulation of lipid metabolism in asthmatic, bronchitic (acute inflammation) and healthy (non-inflammation) children. Eight PAEs and nine OPFRs congeners were found in the serum of children (1 – 5 years old) from Shenzhen, and their total median levels were 615.16 ng/mL and 17.06 ng/mL, respectively. Moreover, the serum levels of mono-methyl phthalate (MMP), tri-propyl phosphate (TPP) and tri-n-butyl phosphate (TNBP) were significant higher in asthmatic children than in healthy and bronchitic children as control. Thirty-one characteristic lipids and fatty acids of asthma were screened by machine-learning random forest model based on serum lipidome data, and the alterations of inflammatory characteristic lipids and fatty acids including palmitic acids, 12,13-DiHODE, 14,21-DiHDHA, prostaglandin D2 and LysoPA(18:2) showed significant correlated with high serum levels of MMP, TPP and TNBP. These results imply PAEs and OPFRs promote the occurrence of childhood asthma via disrupting inflammatory lipid and fatty acid metabolism, and provide a novel sight for better understanding the effects of plastic additives on childhood asthma.

Amoxicillin, a widely used antibiotic in human and veterinary pharmaceuticals, is now considered as an “emerging contaminant” because it exists widespreadly in the environment and brings a series of adverse outcomes. Currently, systematic studies about the developmental toxicity of amoxicillin are still lacking. We explored the potential effects of amoxicillin exposure on pregnancy outcomes, maternal/fetal serum phenotypes, and fetal multiple organ development in mice, at different doses (75, 150, 300 mg/(kg·day)) during late-pregnancy, or at a dose of 300 mg/(kg·day) during different stages (mid-/late-pregnancy) and courses (single-/multi-course). Results showed that prenatal amoxicillin exposure (PAmE) had no significant influence on the body weights of dams, but it could inhibit the physical development and reduce the survival rate of fetuses, especially during the mid-pregnancy. Meanwhile, PAmE altered multiple maternal/fetal serum phenotypes, especially in fetuses. Fetal multi-organ function results showed that PAmE inhibited testicular/adrenal steroid synthesis, long bone/cartilage and hippocampal development, and enhanced ovarian steroid synthesis and hepatic glycogenesis/lipogenesis, and the order of severity might be gonad (testis, ovary) > liver > others. Further analysis found that PAmE-induced multi-organ developmental and functional alterations had differences in stages, courses and fetal gender, and the most obvious changes might be in high-dose, late-pregnancy and multi-course, but there was no typical rule of a dose-response relationship. In conclusion, this study confirmed that PAmE could cause abnormal development and multi-organ function alterations, which deepens our understanding of the risk of PAmE and provides an experimental basis for further exploration of the long-term harm.

Light-induced electron transfer can broaden the substrate range of metalloenzyme. However, the efficiency of photo-enzyme coupling is limited by the poor combination of photosensitizer or photocatalyst with enzyme. Herein, we prepared the nano-photocatalyst MIL-125-NH₂@Ru(bpy) by in site embedding ruthenium pyridine-diimine complex [Ru(bpy)₃^]2+ into metal organic frameworks MIL-125-NH₂ and associated it with multicopper oxidase (MCO) laccase. Compared to [Ru(bpy)₃]²⁺, the coupling efficiency of MIL-125-NH₂@Ru(bpy)₃ for enzymatic oxygen reduction increased by 35.7%. A series of characterizations confirmed that the amino group of laccase formed chemical bonds with the surface defects or hydrophobic groups of MIL-125-NH₂@Ru(bpy)₃. Consequently, the tight binding accelerated the quenching process and electron transfer between laccase and the immobilized ruthenium pyridine-diimine complex. This work would open an avenue for the synthesis of MOFs photocatalyst towards photo-enzyme coupling.

The development of bio-adsorbents with highly selective immobilization properties for specific heavy metals is a great challenge, but has important application value. Biogenic whewellite (BW) with high selectivity for Pb(II) was synthesized by mineral microbial transformation. The selective immobilization properties and mechanism of BW for Pb(II) were analyzed by combining mineral characterization technology and batch adsorption research methods. The results indicated that BW can efficiently and selectively immobilize Pb(II) in single or composite heavy metal adsorption solutions, and the immobilized Pb(II) is difficult to desorb. BW undergoes monolayer adsorption on Pb(II), Q_max ≈ 1073.17 mg/g. The immobilization of Pb(II) by BW is a physico-chemical adsorption process with spontaneous heat absorption and an accompanying increase in entropy. In addition, the sequestration of Pb(II) by BW remains around 756.99 mg/g even at pH = 1. The excellent selective immobilization properties of BW for Pb(II) are closely related to its smaller K_sp, electrostatic repulsion effect, organic-inorganic composite structure, acid resistance and the formation of Pb(II) oxalate. This study provides beneficial information about the recycling of lead in acidic lead-containing wastewater and composite heavy metal contaminated water bodies.