HOCl Formation Driven by Photochemical Processes Enhanced Atmospheric Oxidation Capacity in a Coastal Atmosphere.

Chlorine (Cl) radicals can profoundly affect the atmospheric oxidation capacity and the fates of pollutants. Hypochlorous acid (HOCl) is a potentially crucial Cl precursor, yet the understanding of its formation mechanisms and atmospheric impacts is still limited. Here, we observed high concentrations of HOCl in a coastal city of Southeast China during the autumn of 2022, with an average daytime peak of 181 ppt.

Effects of nocturnal boundary layer subsidence and long-distance transports on PM vertical profiles in the Yangtze River Delta of China measured by PM sensor on unmanned aerial vehicle and PM Lidar.

Atmospheric boundary layer structures and long-distance transports significantly affect fine particulate matter (PM) vertical profiles. In this study, the PM vertical profiles in the Yangtze River Delta (YRD) of China were measured by PM sensor on unmanned aerial vehicle (UAV) and PM Lidar in 2022 (April, June, October) and 2023 (February). The results showed that the PM vertical profiles appeared obvious stratification on the top of nocturnal boundary layer (NBL).

Ground ozone rise during the 2022 Shanghai lockdown caused by the unfavorable emission reduction ratio of nitrogen oxides and volatile organic compounds.

Ground-level ozone (O) pollution has shifted from a scientific issue to a key focus of governmental action in China. In recent years, the concentration of NO in Shanghai has shown a decreasing trend of 3.7% annually, but ozone concentrations have exhibited significant interannual variability, particularly with a noticeable increase in 2022.

Boosting chlorobenzene oxidation over MIL-101(Cr) derived CrO catalysts: The stepwise regulation of CrO clusters and oxygen species by calcination atmospheres.

In this work, CrO catalysts derived from MIL-101(Cr) were prepared for the oxidation of chlorobenzene (CB). The atmosphere of calcination had great effect on the physical and chemical properties of the catalysts. Only the atmosphere of Ar could carbonize and preserve the organic ligands in the structure, retaining the micropore structure and high surface area of MIL-101(Cr).

Simultaneous removal of naphthalene and NO over V-Ce/Ti catalyst: Design of separated active sites for naphthalene degradation and SCR reaction.

V-Ce/Ti catalysts were prepared for the removal of naphthalene and NO in the flue gas. The adverse effects of NH and NO on the naphthalene degradation were weakened on V-Ce/Ti, resulting in a decrease of only 2.5 % in CO selectivity.

Relaxation of Spring Festival Firework Regulations Leads to a Deterioration in Air Quality.

The relaxation of restrictions on Chinese Spring Festival (SF) firework displays in certain regions has raised concerns due to intensive emissions exacerbating air quality deterioration. To evaluate the impacts of fireworks on air quality, a comparative investigation was conducted in a city between 2022 (restricted fireworks) and 2023 SF (unrestricted), utilizing high time-resolution field observations of particle chemical components and air quality model simulations. We observed two severe PM pollution episodes primarily triggered by firework emissions and exacerbated by static meteorology (contributing approximately 30%) during 2023 SF, contrasting with its absence in 2022.

Abundant nitrogenous secondary organic aerosol formation accelerated by cloud processing.

Nitrogenous organic (CHON), crucial for secondary organic aerosol (SOA), forms through poorly studied mechanisms in clouds. Our study explores CHON transformation during cloud processes (CPs). These processes play a vital role in enhancing the variety of CHONs, leading to the formation of CHONs with oxygen atom counts ranging from 1 to 10 and double bond equivalent (DBE) values spanning from 2 to 10.

Large contributions of emission reductions and meteorological conditions to the abatement of PM in Beijing during the 24th Winter Olympic Games in 2022.

To guarantee the blue skies for the 2022 Winter Olympics held in Beijing and Zhangjiakou from February 4 to 20, Beijing and its surrounding areas adopted a series of emission control measures. This provides an opportunity to determine the impacts of large-scale temporary control measures on the air quality in Beijing during this special period. Here, we applied the WRF-CMAQ model to quantify the contributions of emission reduction measures and meteorological conditions.

Photochemistry in the urban agglomeration along the coastline of southeastern China: Pollution mechanism and control implication.

The concentrations of ground-level ozone (O) in China have undergone a rapid increase in recent years, resulting in adverse impacts on the air quality and climate change. However, limited research has been conducted on the coastal urban agglomerations with increasingly serious O pollution. Therefore, in order to better understand in situ photochemistry, comprehensive field observations of O and its precursors, coupled with the model simulation, were conducted in autumn of 2019 at six sites in an urban agglomeration along the coastline of southeastern China.

Widespread missing super-emitters of nitrogen oxides across China inferred from year-round satellite observations.

Nitrogen oxides (NO ≡ NO + NO) play a central role in air pollution and are targeted for emission mitigation by environmental protection agencies globally. Unique challenges for mitigation are presented by super-emitters, typically with the potential to dominate localized NO budgets. Nevertheless, identifying super-emitters still challenges emission mitigation, while the spatial resolution of emission monitoring rises continuously.

Impacts of condensable particulate matter on atmospheric organic aerosols and fine particulate matter (PM) in China.

Condensable particulate matter (CPM) emitted from stationary combustion and mobile sources exhibits high emissions and a large proportion of organic components. However, CPM is not generally measured when conducting emission surveys of PM in most countries, including China. Consequently, previous emission inventories have not included emission rates for CPM.

Quantifying on-road vehicle emissions during traffic congestion using updated emission factors of light-duty gasoline vehicles and real-world traffic monitoring big data.

Light-duty gasoline vehicles (LDGVs) have made up >90 % of vehicle fleets in China since 2019, moreover, with a high annual growth rate (> 10 %) since 2017. Hence, accurate estimates of air pollutant emissions of these fast-changing LDGVs are vital for air quality management, human healthcare, and ecological protection. However, this issue is poorly quantified due to insufficient reserves of timely updated LDGV emission factors, which are dependent on real-world activity levels.

A comparative study of two-way and offline coupled WRF v3.4 and CMAQ v5.0.2 over the contiguous US: performance evaluation and impacts of chemistry-meteorology feedbacks on air quality.

The two-way coupled Weather Research and Forecasting and Community Multiscale Air Quality (WRF-CMAQ) model has been developed to more realistically represent the atmosphere by accounting for complex chemistry-meteorology feedbacks. In this study, we present a comparative analysis of two-way (with consideration of both aerosol direct and indirect effects) and offline coupled WRF v3.4 and CMAQ v5.

Rapid assessments of light-duty gasoline vehicle emissions using on-road remote sensing and machine learning.

In-time and accurate assessments of on-road vehicle emissions play a central role in urban air quality and health policymaking. However, official insight is hampered by the Inspection/Maintenance (I/M) procedure conducted in the laboratory annually. It not only has a large gap to real-world situations (e.

Non-stop industries were the main source of air pollution during the 2020 coronavirus lockdown in the North China Plain.

Unlabelled: Despite large decreases of emissions of air pollution during the coronavirus disease 2019 (COVID-19) lockdown in 2020, an unexpected regional severe haze has still occurred over the North China Plain. To clarify the origin of this pollution, we studied air concentrations of fine particulate matter (PM), NO, O, PM, SO, and CO in Beijing, Hengshui and Baoding during the lockdown period from January 24 to 29, 2020. Variations of PM composition in inorganic ions, elemental carbon and organic matter were also investigated.

City-level air quality improvement in the Beijing-Tianjin-Hebei region from 2016/17 to 2017/18 heating seasons: Attributions and process analysis.

With the implementation of clean air strategies, PM pollution abatement has been observed in the "2 + 26" cities in the Beijing-Tianjin-Hebei (BTH) region (referred to as the BTH2+26) and their surrounding areas. To identify the drivers for PM concentration decreases in the BTH2+26 cites from the 2016/17 heating season (HS1617) to the 2017/18 heating season (HS1718), we investigated the contributions of meteorological conditions and emission-reduction measures by Community Multi-Scale Air Quality (CMAQ) model simulations. The source apportionments of five sector sources (i.

The characteristics of air pollution induced by the quasi-stationary front: Formation processes and influencing factors.

The quasi-stationary front is a significant weather system which influences East Asia in spring. The air quality deteriorated along with the moist circumstance when the quasi stationary front dominated the area. Surface meteorological parameters, air pollutants and PM chemical species were observed during the air pollution episode.

[Source Apportionment of Air Pollutants for a Typical Pollution Event in Zhaoqing].

Based on observational data for pollutants and meteorology, this study analyzed the pollution episode that occurred during Dec 17th to 23th in 2018 in Zhaoqing, Guangdong Province, China. Using the source apportionment model CMAQ-ISAM and the hybrid receptor model, the regional contributions to air pollution were examined. The results showed that low-pressure conditions had an adverse effect on the diffusion of pollutants during this pollution episode in Zhaoqing.

Aerosol-driven droplet concentrations dominate coverage and water of oceanic low-level clouds.

A lack of reliable estimates of cloud condensation nuclei (CCN) aerosols over oceans has severely limited our ability to quantify their effects on cloud properties and extent of cooling by reflecting solar radiation-a key uncertainty in anthropogenic climate forcing. We introduce a methodology for ascribing cloud properties to CCN and isolating the aerosol effects from meteorological effects. Its application showed that for a given meteorology, CCN explains three-fourths of the variability in the radiative cooling effect of clouds, mainly through affecting shallow cloud cover and water path.