Volatile organic compounds (VOCs) are considered as important precursors of ozone in the air, while the contribution of VOCs from pesticide application (PVOCs) to ozone production is unknown. Utilizing data from the Ministry of Agriculture and Rural Affairs of the People's Republic of China and ChinaCropPhen1km, this paper developed PVOC emission inventories with a resolution of 1 km for the main crops (rice, maize, and wheat) from 2012 to 2019 in China. The results revealed that pesticide application is an important VOC emission source in China. Specially, the PVOC emissions from the major grain-producing regions in June accounted for approximately 30% of the annual total PVOC emissions in the local regions. The simulation with the Weather Research and Forecasting Community Multiscale Air Quality model (WRF-CMAQ) indicated that the PVOC emissions increased the mean maximum daily 8-hour average (MDA8) ozone concentration across China by 2.5 ppb in June 2019. During the same period, PVOCs in the parts of North China Plain contributed 10% of the ozone formation. Under the comprehensive emission reduction scenario, it is anticipated that by 2025, the joint implementation of measures including reducing pesticide application, improving pesticide utilization efficiency and promoting solvent substitution will decrease PVOC emissions by 60% compared with 2019, thereby mitigating ozone pollution.

The widespread application of pesticides in China has led to the accumulation of residues in soil. However, few regional studies have fully elucidated the characteristics of pesticide residues in soil (PRS) and the associated risks to the ecosystem and human health on a national level. Therefore, this study aims to compile a dataset on PRS in China from 2006 to 2020 and analyze the interactions and impacts between PRS and the environment. The average concentration of PRS in China was 243.96 μg/kg which was lower than the levels reported in Euro-Americans and other nations. This study revealed PRS in China predominantly originates from organochlorine pesticide residues, with DDTs and HCHs being significant contributors. Despite the high intensity of pesticide application in the Southeast China, PRS concentrations were comparable to those in the Northeast, due to environmental factors that favor pesticide degradation in the Southeast. Both legacy and in-use pesticides were transported by surface runoff or air current, resulting in their accumulation in soil of the lower Yangtze River basin or the piedmont soil of Qinling Mountains, respectively. The average soil environment carrying capacity of PRS in China was -69.5 kg. The ecological risk contributed by PRS in China was mainly at a negligible level. Carcinogenic risks of PRS to adults (4.6 ×10-4) and children (6 ×10-4) exceeded the tolerable thresholds (10-5) by a small margin.

Chlorinated volatile organic compounds (Cl-VOCs) are highly toxic and difficult to degrade. Unregulated release of pollutants presents a grave danger to both the health of humans and the natural environment. Catalytic ozonation is a low-cost and energy-efficient method to degrade Cl-VOCs. Treating readily volatile, highly toxic, and hardly degradable Cl-VOCs required a catalyst with high activity and resistance to chlorine. In this paper, recent advances in the catalytic ozonation of Cl-VOCs at low temperatures are systematically reviewed, including single Cl-VOCs and gas mixtures with Cl-VOCs. The microstructure, morphology, active components, support materials, surface acidity, oxygen vacancy, water and chlorine resistance of various catalysts for catalytic ozonation of Cl-VOCs are thoroughly discussed. It is possible to regulate surface acidity and oxygen vacancy density by Cu and Ce doping and vacuum drying treatment. The hollow structure, nanorod structure, and strong electronic metal-metal interaction (EMMI) coordination structures enhance catalyst chlorine resistance. It is emphasized that the doping of Ce on Mn-based catalysts can simultaneously modulate the catalyst surface acidity and oxygen vacancy, and enhance the chlorine resistance. Finally, the challenges of catalytic ozonation of ClVOCs are presented, and suggestions are provided for the future design of catalysts for catalytic ozonation by Cl-VOCs.

Xylene with high photochemical activity is commonly used as a raw material and organic solvent. The treatment of waste gases containing xylene is a necessary measure to ensure the air quality. Mn/Ce oxide nanorods were prepared using SBA-15 as a template and subjected to vacuum deoxidation for catalytic ozonation of p-xylene. Hydrothermal demolding conduced to detach the nanorods to improve the surface area and porosity, providing massive active sites for catalytic ozonation. The results indicated that numerous Mn-O-Ce solid solution structures formed in Mn/Ce composite oxides, especially Mn0.5Ce0.5Ox, to enhance weak- and medium-acid sites and oxygen vacancies (OVs) on the catalysts. Vacuum deoxidation effectively and facilely raised OVs for the catalysts. Vacuum-deoxidated Mn0.5Ce0.5Ox with the most Mn-O-Ce structures achieved the highest removal rate of pxylene and CO2 selectivity since the most OVs and weak- and medium-acid sites appeared in it compared with the other catalysts. The mechanism of catalytic ozonation may be that p-xylene adsorbed on the acid site of vacuumdeoxidized Mn0.5Ce0.5Ox is attacked by the reactive oxygen species (ROS) generated by the dissociation of O3 on OVs. The degraded p-xylene and its intermediate are finally oxidized by ROS to CO2 and H2O.

Achieving efficient and stable catalysts with chlorine resistance is of great importance for chlorinated volatile organic compounds (CVOCs) degradation. This study developed catalysts containing abundant Ce-O-Cu bonds anchored on titanium nanotubes (TNTs) to form strong electronic metal-metal interaction (EMMI) coordination structure for efficiently catalytic ozonation of 1,2-dichloroethane (1,2-DCE). The occurrence of EMMI resulted in the formation of electron-poor/rich centers and a high proportion of weak-acidity sites over Ce-Cu/TNTs cata-lysts. Among various catalysts, 1Ce1Cu/TNTs exhibited the optimum catalytic performance with 92.5 % of 1,2-DCE conversion and 85.4 % of CO2 selectivity, the long-term stability of 24 h and the good water resistance to 50 % relative humidity (RH). Importantly, the XPS results and DFT calculations suggested Ce drove the Cl atom off Cu species, thus alleviating the chloridion deposit on Cu sites, accelerating the migration of chlorine and offering more redox sites for O3 activation. Electron paramagnetic resonance (EPR) and radical quenching tests identified that center dot OH was a key reactive oxygen species to achieve efficient degradation of 1,2-DCE. The possible reaction pathways for the catalytic ozonation of 1,2-DCE included three parts, including O3 activation, 1,2-DCE pre-liminary degradation and deep oxidation, which obeyed the L-H mechanism.

China has successively put forward ultra-low emission (ULE) transformation plans to reduce the air pollutant emissions of industrial pollutants since 2014. To assess the benefits of the ULE policy on regional air quality for Qinhuangdao, this study developed an emission inventory of nine atmospheric pollutants in 2016 and evaluated the effectiveness of the emission policy in Qinhuangdao's key industries under different scenarios with an air quality model (CALPUFF). The emissions of air pollutants in 2016 were as follows: Sulfur dioxide (SO2) emitted 48.91 kt/year, nitrogen oxide (NOx) emitted 86.83 kt/year, volatile organic compounds (VOCs) emitted 52.69 kt/year, particulate matter (PM10 and PM2.5) emitted 302.01 and 116.85 kt/year, carbon monoxide (CO) emitted 1208.80 kt/year, ammonia (NH3) emitted 62.87 kt/year, black carbon (BC) emitted 3.79 kt/year, and organic carbon (OC) emitted 2.72 kt/year, respectively. The results showed that at the regional level in 2025, the iron and steel industry under the PPC (Peak Production Capacity) scenario had the highest potential for reducing SO2 and NOx emissions, while the cement industry under the PPC scenario excelled in reducing PM10 emissions. As for the industrial level in 2025, the flat glass industry under the ULE scenario would reduce the most SO2 emitted, while the iron and steel industry and the cement industry under the PPC scenario demonstrated the best reduction in NOx and PM10 emissions, respectively. Furthermore, the average annual contribution concentration of SO2, NOx, and PM10 in the air monitoring stations of Qinhuangdao under the PPC scenario was significantly lower than that under the BAU scenario revealed by air quality simulation. It can be concluded that the emission policy in Qinhuangdao will help improve the air quality. This study can provide scientific support for policymakers to implement the ULE policy in industrial undeveloped cities and tourist cities such as Qinhuangdao in the future.

China is the largest producer and exporter of coke globally, which means that it is very important to understand the characteristics of air pollutants and carbon emissions from China’s independent coking industry. This study was the first to establish a bottom-up inventory of the air pollutants and carbon emissions of China’s independent coking industry during 2001–2018 based on continuous emission monitoring system online monitoring data and unit-based corporate information. Based on the developed emission inventory, four scenarios were established to analyze potential emissions reduction of air pollutants and carbon dioxide (CO2) in future. The emissions of particulate matter (PM10 and PM2.5), sulfur dioxide (SO2), black carbon (BC) and organic carbon (OC) decreased by 62.11%, 63.41%, 72.85%, 63.41% and 63.41%, respectively. CO2, carbon monoxide (CO), volatile organic compounds (VOCs) and nitrogen oxides (NOX) emissions increased by 355.51%, 355.51%, 355.51% and 99.74%, respectively. In 2018, PM10, PM2.5, SO2, NOx, BC, OC, CO, VOCs and CO2 emissions were, respectively. 45.20, 16.91, 63.84, 117.71, 5.07, 5.92, 554.91, 1026.58 Gg, and 176.88 Tg. Shanxi province made the greatest contributions to the total emissions of air pollutants and CO2 from this industry by 25.01%. The emission source that contributed most to PM2.5 (SO2 and NOX) emissions was coke pushing (quenching and the coke oven chimney respectively) in 2018. Under the ULE scenario (2018–2035), PM2.5 and SO2 emissions will reduce by more than 30%. Under the PCP scenario, PM2.5 and SO2 emissions will reduce by more than 55%. Under the CBP scenario, CO2 emissions will peak at 197.99 Tg in 2025 and decrease to 70% of the peak in 2035. The results showed the emission characteristics of air pollutants and CO2, future emission with several scenarios and cooperative reduction potential in China’s independent coking industry, which provides scientific support for the development of pollution control strategies.

In response to environmental problems, China has implemented many policies to control its emission of air pollutants and CO2. As a significant source of pollutant emissions, energy use has received special attention. Shaanxi Province is a region of China with major thermal power generation, which consumes a large amount of fossil fuel and causes severe deterioration in ambient air quality. However, it is rich in natural resources that could support the development of solar energy, wind energy, and other renewable clean energies, making it a typical example of a region suitable for energy structure transformation. On the basis of environmental statistical data, field surveys, and data from the Shaanxi Provincial Bureau of Statistics, this study developed an inventory of anthropogenic source emissions of seven pollutants in 2017 in Shaanxi Province. In accordance with the established inventory, various scenarios were considered to analyze the impact of energy structure transformation on air pollutant emissions. In comparison with the Business-as-Usual scenario, the comprehensive clean energy use scenario reduced SO2, NOx, CO, PM10, PM2.5, VOCs, NH3 and CO2 emissions by 32.50%, 33.10%, 14.56%, 26.64%, 16.72%, 2.88%, 4.36% and 36.85%, respectively. Ambitious development of clean energy, such as wind and solar, could greatly reduce the emission of air pollutants, especially CO2, SO2 and NOx, that are derived mainly from fossil fuel combustion, showing that strict control of the energy structure could reduce pollutant emissions. This work is important for quantifying the impact of energy restructuring on regional air quality and providing pollution control policies for environmental managers.

Currently, Tangshan confronts the dual challenge of elevated carbon emissions and substantial pollution discharge from the iron and steel industries (ISIs). While significant efforts have been made to mitigate air pollutants and carbon emissions within the ISIs, there remains a gap in comprehending the control of carbon emissions, air pollutant emissions, and their contributions to air pollutant concentrations at the enterprise level. In this study, we devised the Air Pollutant and Carbon Emission and Air Quality (ACEA) model to identify enterprises with noteworthy air pollution and carbon emissions, as well as substantial contributions to air pollutant concentrations. We constructed a detailed inventory of air pollutants and CO2 emissions from the iron and steel industry in Tangshan for the year 2019. The findings reveal that in 2019, Tangshan emitted 5.75 × 104 t of SO2, 13.47 × 104 t of NOx, 3.55 × 104 t of PM10, 1.80 × 104 t of PM2.5, 5.79 × 106 t of CO and 219.62 Mt of CO2. The ACEA model effectively pinpointed key links between ISI enterprises emitting air pollutants and carbon dioxide, notably in pre-iron-making processes (coking, sintering, pelletizing) and the Blast furnace. By utilizing the developed air pollutant emission inventory, the CALPUFF model assessed the impact of ISI enterprises on air quality in the Tangshan region. Subsequently, we graded the performance of air pollutant and CO2 emissions following established criteria. The ACEA model successfully identified eight enterprises with significant air pollution and carbon emissions, exerting notable influence on air pollutant concentrations. Furthermore, the ACEA outcomes offer the potential for enhancing regional air quality in Tangshan and provide a scientific instrument for mitigating air pollutants and carbon emissions. The effective application of the ACEA model in Tangshan’s steel industry holds promise for supporting carbon reduction initiatives and elevating environmental standards in other industrial cities across China.

To improve the ecological environment, provinces in China have set ambitious goals for the electrification of fossil-fuel-powered vehicles (FVs) and the promotion of electric vehicles (EVs). Hainan is the first province to propose a clean energy target that schedules the banning of new FVs sales from 2030. Therefore, Hainan is a good case study to illustrate how this policy might improve regional air quality over the coming years. This study first developed an anthropogenic emission inventory of seven major air pollutants in 2017 in Hainan. The total emissions of CO, NOx, NH3, volatile organic compounds (VOCs), PM10 and PM2.5 and SO2 in 2017 were esti-mated as 247.56, 69.61, 61.87, 41.38, 37.02, 19.82, and 8.55 kt, respectively. Using the developed emission inventory, multiple scenarios of economic development were considered to assess the benefits to air quality from Hainan's goal of electrification. In comparison with 2017, the reductions in emissions of SO2, NOx, CO, PM10, PM2.5, VOCs, and NH3 by 2045 were projected to be 5.45 (11.11%), 275.07 (57.32%), 675.51 (34.07%), 8.39 (5.73%), 7.73 (8.24%), 81.15 (9.76%), and 4.89 (0.91%) kt, respectively, under the all-electric vehicle scenarios. These results indicate that this policy will not only reduce the emission of air pollutants but also avoid complex O3 pollution in the future. The findings of this work elucidate the effects of vehicle electrification policies on regional air quality and provide scientific support for policymakers in developing pollution control strategies.

MnxCe1-xO2 nanorod catalysts were synthesized using SBA-15 as a template. In MnxCe1-xO2, ultrahigh Mn ions entered into the CeO2 lattice, resulting in Mn-O-Ce solid solution generation with increasing surface oxygen vacancies. Mn-O-Ce structure lessened crystalline MnO2 to decrease strong-acidity sites but to increase weak moderate-acidity sites on the surface of MnxCe1-xO2. Vacuum drying deoxidated the surfaces of catalysts to elevate their surface oxygen vacancies. The deoxidation also decreased strong-acidity sites while increasing weak-moderate-acidity sites on the surface of MnxCe1-xO(2). Among MnxCe1-xO2 catalysts, NMn0.4Ce0.6O2 was screened out as the optimal catalyst, with outstanding catalytic performance and long-term stability, whose 1,2dichloroethane (DCE) conversion and CO2 selectivity could reach up to 96% and 82%, respectively. The results indicated that the synergistic effect between surface acidity and oxygen vacancy played a critical role in the catalytic ozonation of DCE. The mechanism analysis indicated that chlorine species from DCE decomposition were easily bound to manganese oxides to form MnOxCly on NMnO2 during catalytic ozonation, leading to the deactivation of NMnO2 and the formation of polychlorinated byproducts. Most of chlorine species were oxidated into ClO(3-)and ClO(4-)and further removed as Cl-2 and HCl on NMn0.4Ce0.6O2 during the catalytic ozonation of DCE.

Solvents, components of pesticide emulsifiable concentrates (ECs), emit quantities of volatile organic compounds (VOCs) into the atmosphere. In the air, their active involvement in oxidative chemical reactions with oxidants exposed to ultraviolet solar radiation can result in the formation of ozone. The quantitative assessment of VOC emissions from agricultural pesticide applications remains hampered by many factors, especially the volatility coefficient of solvents in pesticides. Therefore, this study identified solvents in 20 widely used pesticide products in China. The volatility coefficients of the solvents were investigated based on a spraying test to evaluate VOC emissions from agricultural pesticide applications and their ozone formation potential (OFP). The results suggest that VOC emissions from agricultural pesticide applications amount to 0.60 Mt in 2017, with insecticides, fungicides, and herbicides contributing 0.39 Mt, 0.12 Mt, and 0.09 Mt of VOCs, respectively. Since VOC emission and maximum incremental reactivity (MIR) led to an OFP value (2.1 g ozone/g product) for insecticides, a primary consideration should be to decrease use of solvents with high volatility coefficients and large MIR values in insecticide products. This work could provide valuable insights regarding response options to reduce VOC emissions and ozone formation.