This study adopts a life cycle assessment (LCA) framework to define the system boundary for greenhouse gas (GHG) emission accounting across the entire food waste collection, transportation, and treatment process. Emission sources and gas types were identified to establish a comprehensive emission inventory, upon which a modular and decomposable GHG emission accounting model was developed based on the emission factor method. The results indicate that the full-process system boundary encompasses nine accounting units and seven major categories of GHG emission sources. Compared to conventional models, the proposed model demonstrates distinct advantages in accounting accuracy, modularity, flexibility, and scenario adaptability. A case study was conducted for the Chaoyang District of Beijing to validate the model. The findings show that GHG emissions are particularly significant at the waste disposal sites and during vehicle transportation, with emission rates of 1.38 and 1.32 tCO₂e/d, respectively. Fossil fuel combustion was identified as the dominant emission source, contributing 24.4% of total emissions. In the treatment and disposal phase, wastewater treatment exhibited the highest emissions, reaching 4.05tCO₂e/d, or 32.3% of the total. Carbon offsetting efforts achieved a reduction of 53.2tCO₂e/d. Sensitivity analysis revealed that food waste generation volume and biogas yield have the most significant impact on total GHG emissions, while the influence of total vehicle kilometers traveled and electricity emission factors was comparatively minor.

A power system flexibility optimization model, NEMO-China-Flexibility, was constructed in this study, integrating power system flexibility enhancement into a carbon-neutral framework for China's regional power grids. Based on regional economic development levels, energy demand intensity, renewable resource development potential, and flexibility enhancement, four distinct scenarios were designed: baseline scenario, high-penetration variable renewable energy scenario, flexibility enhancement scenario, and comprehensive scenario. The effects of flexibility enhancement were analyzed through scenario comparison. The results showed that integrated source-grid-load-storage flexibility enhancement could significantly enhance the power system's capability to address supply-demand fluctuations and improve renewable energy consumption. Among various flexibility resources, coal power was the foundational flexibility resource, while energy storage exhibited the greatest development potential. Additionally, flexibility enhancement delivered co-benefits such as reducing carbon emissions and lowering power system operational costs.

Regional-scale mobile observations of atmospheric isoprene were conducted along a 2000km east-west transect in China's subtropical forest region using a mobile laboratory equipped with a high-resolution proton transfer reaction time-of-flight mass spectrometer (PTR-TOF-MS). The objective of this study was to elucidate the spatial distribution patterns of isoprene in this area. The results revealed significant spatial heterogeneity in isoprene concentrations, with an average value of (0.635 ± 0.204) μg/m³. The isoprene concentration in the Jiangnan forests, characterized by widespread bamboo and predominantly subtropical evergreen broadleaf species, was (0.629 ± 0.116) μg/m³, which was approximately 32.8% higher than the (0.474 ± 0.155) μg/m³observed in the Guizhou forests, primarily composed of conifers. These findings indicate that the spatial distribution and emission intensity of isoprene in forested areas are significantly influenced by vegetation composition. Moreover, in the industrially dense Zhejiang region, the isoprene concentration reached (0.881 ± 0.155) μg/m³, representing increases of 86.2% and 40.1% compared to the Guizhou and Jiangnan forests, respectively. These results suggest that in addition to the rich diversity of plant species, anthropogenic factors such as industrial and traffic activities also likely contribute to the elevated isoprene concentrations observed in this region.

To clarify the concentration characteristics and sources of volatile organic compounds (VOCs) in a typical northwestern petrochemical park during summer, continuous monitoring of 116 VOCs was conducted from June to July 2024. The measured VOC (MVOCs) concentrations were obtained, and the initial VOC (InVOCs) and consumed VOC (CVOCs) concentrations were calculated. Whereafter, the positive matrix factorization (PMF) was used to analyze the sources of MVOCs and InVOCs, the principal component analysis (PCA) was employed to identify the sources of CVOCs, and the contribution of the major factors of each VOC source to ozone (O₃) formation was also calculated. The results indicated that during the observation period, oxygenated VOCs (OVOCs) and alkanes exhibited the highest concentration contributions among both the measured total VOCs (M-TVOC) and the initial total VOCs (In-TVOC), with a diurnal variation characterized by bimodal peaks in the morning and evening. The consumed total VOCs (C-TVOC) exhibited a strong correlation (r = 0.89) with the diurnal variation of O₃ concentrations, with alkenes and OVOCs being the dominant contributing species. Among the top ten ozone formation potential (OFP) species for all three VOCs categories, alkenes and aldehydes were predominant. .The sources of MVOCs and InVOCs were ranked as follows: petrochemical sources > combustion sources > vehicle emissions > biogenic emissions > solvent utilization sources.. As for CVOCs, the sources were identified aspetrochemical sources (51.1%) > gasoline evaporation (26.0%) > biogenic emissions (18.2%) > solvent utilization sources (4.8%). Among these, petrochemical sources were identified as the largest contributor to O₃formation. The results indicated that reducing emissions from petrochemical sources, combustion sources, and vehicle emissions is an effective strategy for controlling summer VOCs around the park. Additionally, cutting emissions from petrochemical sources and solvent utilization sources can significantly decrease the contribution of VOCs to O₃ formation.

Dominated crops Triticum aestivum, Zea mays, Glycine max, and Arachis hypogaea were selected to study the Volatile Organic Compounds (VOCs) emission characteristics and their atmospheric reactivity of crop. The dynamic enclosure system and the thermal desorption and gas chromatography-mass spectrometry (TD-GC-MS) technique were used for the quantitative analysis of VOCs emission. The VOCs emission rate and chemical composition characteristics of four crops were studied, and their hydroxyl radical consumption rate (L_OH) and O₃ formation potential (OFP) were calculated. The results showed that the total VOCs emission rates of four crops were ranked as Arachis hypogaea ((43.27 ± 18.8) μg/(g·h)) > Triticum aestivum ((21.63 ± 8.24) μg/(g·h)) >Glycine max ((2.97 ± 0.67) μg/(g·h)) > Zea mays ((0.36 ± 0.15) μg/(g·h)). The major emission contributing components of each crop included isoprene, n-heptane, cyclopentane, p-xylene, and m-xylene. The composition of VOCs emitted by the four crops were different. Triticum aestivum mainly emitted alkanes and aromatics, Zea mays mainly emitted monoterpenes, Glycine max mainly emitted alkanes, and Arachis hypogaea mainly emitted isoprene. Alkenes were detected only in VOCs emitted from Glycine max. The L_OH and OFP of VOCs emitted by different crops also followed the same ranking: Arachis hypogaea > Triticum aestivum >Glycine max > Zea mays. Isoprene, limonene, trans-β-ocimene, β-caryophyllene, and cyclopentane were the key active components of VOCs emitted by the four crops.

As a typical photochemical product, atmospheric peroxyacetyl nitrate (PAN), which has received widespread attention for the important role it plays in atmospheric photochemical processes, has been studied relatively late due to difficulties in monitoring. In order to deeply investigate the concentration level of PAN and its generation mechanism in industrial cities, this study conducted online observations of PAN and other pollutants for one year from March 2023 to February 2024 in Zibo City, North China Plain. The average concentration of PAN during the study period was 1.09×10^-9 (0.03~10.07×10^-9), and the four-seasonal concentration ranking showed a pattern of winter (2.07×10^-9) > autumn (0.98×10^-9) > spring (0.64×10^-9) > summer (0.61×10^-9). There was a significant difference in the time of occurrence of the peak daily change concentration, with the peak occurring at midday (12:00) in summer and delayed to the afternoon (17:00) in winter. The results of the generalised additive model (GAM) showed that the PAN concentration was significantly affected by temperature and atmospheric oxidability. Calculations based on the zero-dimensional box model (F0AM) showed that acetaldehyde contributed the most to peroxyacetyl (PA) (69%), followed by photolysis (18%) and oxidation (11%) of methylglyoxal, and that the loss of PA was dominated by the interaction of nitric oxide (NO) (18%) and nitrogen dioxide (NO₂) (81%) with PA. The relative incremental reactivity (RIR) showed that PAN generation was sensitive to NO_x. This study enriches the understanding of the characteristics of atmospheric PAN pollution and its formation mechanism in North China and provides scientific and technological support for air pollution control.

Based on the chemical components in PM_2.5 and meteorological data from the online monitoring of Zibo Super Station, relevant analyses were conducted for the PM_2.5 pollution period from December 25^th, 2023 to January 6^th, 2024. The results showed that during the observation period, the average concentration of PM_2.5 was (133±67) μg/m³, and the average proportion of secondary inorganic ions (NO₃^-,SO₄^2- and NH₄⁺) was 58.3%. Among them, the concentration of NO₃^- was the highest, accounting for 26.9%. The average values of the sulfur oxidation ratio and nitrogen oxidation ratio were 0.46 and 0.29, respectively, both greater than 0.1, indicating that there was an obvious secondary formation process of SO₄^2- and NO₃^- during this pollution process. The formation of NO₃^- was mainly limited by HNO₃, and the heterogeneous reaction under high-humidity conditions was the main pathway for its formation. The Positive Matrix Factorization (PMF) model identified six main sources of PM_2.5, namely secondary nitrates (30.2%), secondary sulfates (26.8%), coal burning sources (18.4%), motor vehicle sources (15.3%), industrial sources (5.3%), and dust sources (4.0%). Concentration Weighted Trajectory (CWT) analysis further revealed the main contribution path areas of sources with a relatively large contribution to PM_2.5, such as secondary nitrates, which were mainly from the local area and surrounding cities.

The passive NO_x adsorbent, Pd-SSZ-13 with a Pd loading of 1.64wt.%, was prepared by the ion-exchange method. Then, the Pd-SSZ-13 was subjected to thermal and hydrothermal aging treatments separately for 10h under mild conditions: at a temperature of 700℃ and in an atmosphere consisting of 10%O₂, 2%H₂O (for hydrothermal treatment only), and N₂ as the balance. The effects of these treatments on the NO_x adsorption/desorption performance of Pd-SSZ-13 were investigated. The physicochemical properties of adsorbents and the NO adsorption process were characterized using N₂ adsorption-desorption, XRF, ICP-OES, XRD, SSNMR, XPS, TEM, NH₃-TPD and in situ Drifts techniques. The results showed that when the feed gas contained 2%H₂O, the SSZ-13 support was unable to adsorb NO_x, whereas Pd-SSZ-13 exhibited NO_x adsorption during both the adsorption stage and the temperature-programmed stage (100~230℃), demonstrating an adsorption capacity of 81.3μmol/g. The NO_x desorption temperature range (230~493℃) fell within the active temperature window of SCR catalysts, and complete NO_x desorption was achieved. After undergoing thermal and hydrothermal aging treatments, the NO_x adsorption capacity of Pd-SSZ-13 in the presence of H₂O further increased to 113.4 and 126.2μmol/g, respectively, and the thermally aged sample showed better cyclic stability. Although thermal and hydrothermal aging treatments induced partial dealumination of the SSZ-13 framework, they neither altered the micropore characteristics of SSZ-13 nor caused structural collapse or framework destruction. Instead, the aging processes promoted the migration of Pd species from external surfaces to interior pores, enhanced the dispersion of Pd, and increased the amount of Pd²⁺(Z-[Pd²⁺(OH)]⁺ and Z₂-Pd²⁺) sites, thereby improving the NO_x adsorption-storage capability of Pd-SSZ-13. Compared with the hydrothermally-aged Pd-SSZ-13, the thermally-aged sample showed less framework dealumination, a higher specific surface area and a larger micropore volume, and better dispersion of Pd species, all of which likely contributed to its superior cyclic stability. With H₂O in the feed gas, NO was mainly adsorbed and stored at the Pd²⁺ sites in the forms of Pd⁺-NO, Pd²⁺-NO and hydrated Pd²⁺-NO species, with the competitive adsorption of H₂O attenuated at elevated temperatures. During the thermal and hydrothermal aging of Pd-SSZ-13, the abundant Brønsted acid sites likely played an important role in facilitating the migration of Pd species and the formation of Pd²⁺ sites.

To explore the impact of the increase in new energy vehicles, such as LNG heavy-duty trucks and hybrid vehicles, on tunnel ventilation and to address the issue of ventilation flow calculation discrepancies caused by insufficient consideration of their emission characteristics in current design codes, this study builds a tunnel vehicle baseline emission factor library and a refined tunnel ventilation calculation method based on the emission characteristics of new energy vehicles. Factors such as slope and vehicle fleet composition are taken into account. The study uses the Huayan Tunnel as a case study and calculates the required ventilation flow for different penetration rates of new energy vehicles based on the updated emission factor library. The results are then compared with those obtained using the existing ventilation calculation methods. The results indicate that the refined method significantly improves the accuracy of the required ventilation flow calculation. When the design year is set to 2030, the required ventilation flow for NO₂ dilution is 305.5% higher than that calculated using the International Tunnel Ventilation Report (PIARC 2019) method, while the required ventilation flow for CO and VI dilution decreases by 10% and 6.5%, respectively. Additionally, for every 10% increase in LNG heavy-duty truck penetration, the required ventilation flow for NO₂ dilution increases by approximately 55%. In contrast, the impact of hybrid and pure electric vehicles on the required ventilation flow is negligible. The traditional design codes, which focus on CO and VI as the main control indicators, are no longer applicable to fleet structures with a rapidly increasing proportion of new energy vehicles. The required ventilation flow for NO₂ dilution will become a key control indicator for future tunnel ventilation design.

This study evaluated the interannual variations in the sources, source-specific metals, and health risks of PM_2.5-bound heavy metals (HMs) based on observational data in heating seasons from 2020 to 2022 in Wangdu County, aiming to assess the impact of "coal-to-gas" (CTG) policy on air quality at rural areas. The CTG policy continued to play a positive role, both PM_2.5 and 16HMs (Cr, Pb, Tl, Ba, Sb, Sn, Cd, Sr, As, Zn, Cu, Ni, Co, Fe, Mn, and V) showed a declining trend year by year with annual average reductions of 30.4% and 43.4%, respectively. Positive Matrix Factorization (PMF) model was used to analyze the sources of HMs and results indicated that the contribution of coal combustion (CC) decreased by an average of 11.8% annually. However, biomass burning (BB) increased year by year and leaped the largest contributor (33.7%) in the winter 2022, primarily driving by natural gas shortages and heating cost rises at rural areas. The concentrations of CC marker elements As and Pb decreased by 20.7% and 48.5% annually, and CC fractions declined by 15.6% and 13.5% per year, respectively. Similarly, the concentrations and fractions of BB marker element K increased by 20.6% and 7.4% annually. Industrial emissions (IE), vehicle emissions (VE), and fugitive dust (FD) all exhibited upward trends over the years. For health risk assessment: only As and Cr surpassed threshold of carcinogenic risks, and there were derived from CC and IE, therefore, CC and IE were identified as the main contributors to carcinogenic risks. However, individual elements did not exceed the threshold of non-carcinogenic risks, but the total carcinogenic risks persisted from 2020 to 2022. Specially, the total carcinogenic risks for children were 64%, which was much higher than 36% for adults. Together, adults only have non-carcinogenic risks in 2020, while children were always faced with non-carcinogenic risks. As a main contributor to both carcinogenic and non-carcinogenic risks for As, since the annual average contribution of CC to As emissions has dropped significantly by 15.6%, resulting in a year by year decline for carcinogenic and non-carcinogenic risks.