Based on observational data of carbonaceous aerosols collected in Chengdu from June 15, 2020 to April 15, 2022, this study analyzed the temporal variation characteristics of their concentrations and optical properties, and explored the influence of different pollution processes on carbonaceous aerosol levels. The results show that the diurnal variations of carbonaceous aerosol components exhibited distinct bimodal patterns, primarily influenced by traffic rush hours and the development of the planetary boundary layer. The mass concentrations of total carbon (m_TC), elemental carbon (m_EC), and organic carbon (m_OC) peaked in winter, with average values of 8.8 ± 6.4, 2.8 ± 2.1, and 6.0 ± 4.5 μg/m³, respectively, and were lowest in summer. During winter, the mean values of the mass ratio of OC to EC (m_OC/m_EC:2.8 ± 0.9), the absorption Ångström exponent (α:1.5), and the contribution of brown carbon (BrC) to total absorption at 370nm (P_ErC:34 ± 19%) all reached their seasonal maxima. Statistical analysis of the relationship between carbonaceous aerosol components and pollution levels indicates that air pollution in Chengdu is mainly driven by the accumulation and aging of primary emissions under stagnant meteorological conditions. As pollution becomes more severe, the proportion of primary components in carbonaceous aerosols increases. Firework emissions during the Spring Festival were found to increase the contribution of BrC, while emissions and accumulation from motor vehicles led to an increased contribution of black carbon (BC). The relative contribution of BC can serve as an indicator of primary emission accumulation and subsequent aging processes during pollution events. This study provides valuable data support for expanding the carbonaceous aerosol database in Chengdu and for understanding the formation mechanism of wintertime compound pollution in the region.

Based on the environmental statistics data and departmental survey data of Shaanxi Province in 2022, the emission inventory of atmospheric pollutants and CO₂ of Shaanxi Province in 2022 was established by a combination method of bottom-up and top-down. The results indicate that the total emissions of SO₂, NO_x, CO, VOCs, NH₃, PM₁₀, PM_2.5, BC, OC and CO₂ were 64.0×10³, 31.2×10⁴, 19.3×10⁵, 21.5×10⁴, 34.0×10⁴, 67.9×10⁴, 20.8×10⁴, 11.7×10³, 24.0×10³, 33.1×10⁷ tons, respectively. The primary source of SO₂ was electricity generation and heating supply; the primary source of NO_x and BC was diesel vehicles; the primary source of CO was the iron and steel industry; the primary source of VOCs was the coking industry; the primary source of NH₃ was livestock and poultry farming; the primary source of PM₁₀ and PM_2.5 was the road dust; and the primary source of OC was biomass stoves. Yulin, Xi'an and Weinan were the major cities with SO₂ and PM₁₀ emissions; Yulin, Xi'an and Hancheng were the major cities with PM_2.5 emissions; Xi'an, Yulin and Xianyang were the major cities with NO_x emissions; Xi'an, Yulin and Yan'an were the major cities with VOCs emissions; Hancheng, Yulin and Xi'an were the major cities with CO emissions; Yulin, Weinan and Baoji were the major cities with NH₃ emissions; Yulin, Xi'an and Xianyang were the major cities with BC emissions; Yulin, Xi'an and Weinan were the major cities with OC emissions. On this basis, the pollution and carbon reduction effects of air pollutants and CO₂ emission reduction measures were analyzed, and it was found that the cleanification of civil energy, the electricity generation of cleaner power energyin power plants and the renovation of coal-fired boilers all have pollution and carbon reduction effects,while the electricity generation of cleaner power energyin power plants have the highest synergistic effect.

Taking the well-structured rod-like SBA-15 as support, Pd₁Co_x/SBA-15 bimetallic catalysts with different palladium(Pd) and cobalt(Co) molar ratios were prepared by adjusting the Co content for acetone (C₃H₆O) catalytic oxidation. Among these, the Pd₁Co₁/SBA-15 catalyst was found to exhibit superior performance for the low-temperature oxidation of C₃H₆O, achieving 90% conversion at 220℃, along with high CO₂ selectivity and thermal stability. Characterization by SEM, XRD, FT-IR, and N₂ adsorption-desorption was conducted, and it was revealed that Pd₁Co₁/SBA-15 possessed the optimal Pd/Co ratio and a higher specific surface area, which were crucial for the stabilization and exposure of active sites. Further investigations using H₂-TPR, O₂-TPD, and XPS indicated that the primary active oxygen species in Pd₁Co_0.5/SBA-15 and Pd₁Co₃/SBA-15 were chemisorbed oxygen, while surface lattice oxygen was predominantly present in Pd₁Co₁/SBA-15. Moreover, the transformation of abundant active oxygen species in Pd₁Co₁/SBA-15 was significantly promoted. The reaction mechanism of acetone oxidation over Pd₁Co₁/SBA-15 was elucidated by in-situ infrared spectroscopy. The decomposition path of acetone molecules over Pd₁Co₁/SBA-15 catalyst was determined as C₃H₆O→CH₃CH₂OH→CH₃COO^-→COO^-→CO₂, which further indicated that enhanced surface lattice oxygen can significantly accelerate activation and cleavage during the acetone oxidation process.

This study investigated the advection and diffusion patterns of hydrogen sulfide (H₂S) in a prototype sewer network of a residential area in Xi'an, using Ventsim to simulate both natural and forced ventilation conditions. The results show that the simulated and measured values are within 10% difference, which confirms the reliability of the Ventsim simulation method. Forced ventilation increased the air velocity in sewer pipes by 8.8% compared to natural ventilation conditions. It was further found that utilizing only an intake or exhaust fan required 108s and 105s, respectively to completely expel hazardous gases from the sewage network. Simultaneous operation of both intake and exhaust fans significantly enhanced the migration rate of harmful gases, reducing the expulsion time to 55s. Nevertheless, using only an intake fan may cause H₂S to escape through small openings on manhole covers. These findings provide technical support for predicting and controlling hazardous gases within sanitary sewer networks, contributing to infrastructure safety and operational maintenance.

Cr (VI) typically exists as a negatively charged anion, whereas Cr (III) is positively charged as a cation. The positively charged Cr (III) obtained through the reduction of Cr (VI) can further adsorb Cr (VI), thereby enabling cyclic adsorption and enrichment of chromium species. In this study, polypyrrole (PPy) was dispersed in chitosan/polyethyleneimine (CS/PEI) hydrogel network to prepare a composite aerogel named CS/PPy/PEI. The composition and structure of CS/PPy/PEI were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), Zeta potential and UV-vis-NIR spectroscopy. Based on the valence transformation of Cr (VI)/Cr (III), the cyclic enrichment process of Cr (VI) adsorption-photoreduction-immobilization-re-adsorption is established in CS/PPy/PEI aerogel. The results showed that the introduction of ascorbic acid as a co-catalyst during the photocatalytic reduction process could further enhance the enrichment of chromium by CS/PPy/PEI, and the adsorption capacity of CS/PPy/PEI could reach 279.69mg/g after 6cycles of enrichment. Since CS/PPy/PEI aerogels do not contain any other metals, high-purity chromium can be effectively recovered through simple calcination.

This study addresses challenges in conventional advanced oxidation processes (AOPs), including mass transfer limitations of endogenous mediators, and reliance on energy-intensive/sacrificial agents' consumption to maintain the catalytic activity, by proposing an innovative strategy that employs trace H₂O₂ to micro-regulate dual-reaction center (DRC) catalysts for enhanced water self-purification. DRC catalyst (FZSO) with surface electron-polarized distribution can effectively enhance interactions between naturally dissolved oxygen and pollutants, thereby overcomes mass transfer limitations and obviously enhances water self-purification. This process radically changes the role of H₂O₂—innovatively repurposed from the sacrificial agent in AOPs to the precision micro-regulator in DRC system, largely reducing consumption in water treatment. Experimental results demonstrate that under micro-regulation with only 1mmol/L H₂O₂, the FZSO-DRC system achieved complete ciprofloxacin removal within 15min, with less than 10% H₂O₂ consumption. FZSO system also exhibits strong adaptability and stability for complex water matrices (pH or salinity ions). This study proposes a breakthrough in energy-efficient water purification by amplifying natural water self-purification capacity through the FZSO-DRC system, providing new technical perspective for developing high-efficiency, low-consumption water treatment processes.

To efficiently remove Cd (II) from water, this study prepared a novel adsorbent by compositing hydrochloric acid-activated attapulgite with hydrochar and in-situ loading iron-manganese bimetallic oxides. The material was characterized by SEM-EDS, XPS, XRD, FTIR, and BET, revealing the synergistic chemisorption of Cd (II) by iron-manganese oxides and functional groups such as hydroxyl and carboxyl groups. The optimally proportioned adsorbent exhibited a maximum Cd (II) adsorption capacity of 66.8mg/g. The adsorption process followed pseudo-second-order kinetics and the Langmuir model, indicating predominantly monolayer chemisorption. After five adsorption-desorption cycles, the material retained approximately 75% of its initial adsorption capacity, demonstrating excellent regeneration performance. These experimental results provide a reliable technical basis for low-cost, highly efficient, and reusable remediation of heavy metals in water bodies.

This study investigated the removal effectiveness and mechanism of mixed surfactant solutions composed of sodium dodecyl sulfate (SDS) and polyethylene glycol octylphenyl ether (TX100) on trichloroethylene (TCE) contamination through column and three-dimensional sand tank experiments, combined with electrical resistivity tomography (ERT). The column experiments revealed a significant synergistic effect of surfactant concentration and mixing ratio on TCE removal. When the mixing ratio α was 0.9, all tested concentrations exhibited optimal removal performance, with the 3.0g/L solution showing the highest resistivity change percentage (91.37%), followed by 1.5g/L (87.07%) and 0.5g/L (81.25%). Resistivity monitoring indicated that most TCE removal occurred during the first pore volume (pv) of surfactant injection, after which the resistivity stabilized, suggesting the completion of the removal process. In the sand tank experiments, the resistivity difference in the TCE-contaminated region increased from an initial value of approximately 60 Ω·m to 120~140 Ω·m during TCE injection, reflecting the accumulation of contaminants. After water injection, the resistivity difference decreased to 30~60 Ω·m with a localized rebound to 80~140 Ω·m, indicating dilution and redistribution of the contaminant. Following the injection of the mixed surfactant solution (3.0g/L, α = 0.9), the resistivity difference in the contaminated area significantly decreased to the initial range (approximately 20~60 Ω·m), demonstrating a remarkable removal effect. ERT effectively visualized the contaminant removal process in real time, revealing spatial distribution changes of TCE across different depths and cross-sections. This non-invasive, real-time, and three-dimensional monitoring approach highlights the unique advantages of ERT in tracking and evaluating contaminant remediation processes.

This study addresses the challenge of low-temperature nitrogen removal in the anaerobic ammonium oxidation (ANAMMOX) process. By using cold shock, the nitrogen removal performance of immobilized ANAMMOX particles (R3) at various low temperatures was successfully improved. The results showed that, at the low temperatures ranging from 23℃ to 6℃, the nitrogen removal efficiency of R3 particles was significantly higher than that of non-cold-shocked immobilized particles (R2) and non-immobilized ANAMMOX sludge (R1), with the advantage being especially pronounced at 12 and 6℃. The higher specific ANAMMOX activity (SAA) and biomass concentration (MLVSS) of R3 particles were key factors in maintaining efficient nitrogen removal at low temperatures. At 12 and 6℃, the SAA of R3 was 20~22 times higher than that of R1 and 12~14 times higher than R2; the MLVSS of R3 reached as high as 6059~4732mg/L. This was attributed to the fact that cold shock improved the metabolic proliferation of functional bacteria, extracellular polymeric substance (EPS) regulation, and the secondary structure of proteins (PN) in EPS. Notably, the relative abundance of Candidatus Brocadia in R3 was significantly increased, enabling it to maintain activity at extremely low temperatures. Additionally, the increase in the abundance of ANAMMOX genera and cold-tolerant bacterial genera within the particles facilitated the regulation of EPS secretion and improved bioaggregation. This study provides an effective approach for promoting the low-temperature application of the ANAMMOX process.

This study employed a partial denitrification-Anammox biofilm system (PDA-Bf) to treat simulated municipal wastewater, with a focus on exploring its nitrogen removal performance under mesophilic conditions (34℃). After 317 days of operation, the results indicated that under an influent carbon-to-nitrogen ratio (C/N) of 2.1, the total nitrogen (TN) concentration in the effluent was reduced to 10.94mg/L, with an average TN removal rate of 82.6%. Moreover, the contribution of the Anammox pathway to TN removal significantly increased over time. The study found that the abundances of the denitrifying genus Thauera and the anammox genus Candidatus Brocadia in the biofilm significantly increased with operation time. Thauera increased from 0.37% on day 250 to 4.11% on day 305, and Ca. Brocadia rose from 0.27% to 3.51%. The two genera worked well in synergy. The outer layer of the biofilm had a high abundance of genes encoding nitrate reduction, such as narG (55152hits), narH (35866hits), and narI (16506hits), indicating that this area was suitable for the growth of denitrifying bacteria and provided nitrite for the Anammox reaction. In contrast, the inner layer of the biofilm had a higher abundance of the Anammox-related hdh gene (1174hits), and lower abundances of nitrite reduction genes nirK (13400hits) and nirS (3954hits), maintaining a higher nitrite concentration and creating a suitable environment for Anammox bacteria (AnAOB). This stratified microbial community structure suggests that the outer and inner layers of the biofilm are respectively suitable for the growth of Thauera and Ca. Brocadia, jointly promoting the efficient nitrogen removal performance of the system.