PM2.5 concentrations have decreased remarkably in China recent years, coinciding with a more rapid decrease SO2 and slower NO2 concentrations, while O3 increased. Correlations between key gaseous pollutants were studied to identify linked trends as means of understanding the impacts air pollution control China. In most cities, PM2.5–NO2 correlation coefficients higher than PM2.5–SO2 coefficients, gap tended expand quality improved. Multiple linear regression also indicated that sensitive...

We present a novel mechanism for the formation of photocatalytic oxidants in deliquescent NaCl particles, which can greatly promote multiphase photo-oxidation SO2 to produce sulfate. The photoexcitation [Cl––H3O+–O2] complex leads generation Cl and OH radicals, is key reason enhancing aqueous-phase oxidation accelerating oxidation. mass normalization rate sulfate production from photoreaction on droplets could be estimated 0.80 × 10–4 μg·h–1 at 72% RH 1.33 81% RH, equivalent known O3...

The sandy subterranean estuary (STE) connecting fresh groundwater to saline sea water is characterized by strong geochemical (salinity, redox, and pH) gradients, with evidence emerging for its role as a hot spot consumption of labile substrates. This inspired us conduct study evaluate whether this holds true dissolved organic matter (DOM), especially given the still mysterious origin marine recalcitrant DOM. Here, characterization DOM 21 samples (depth 1-13 m, salinity 3.9‰ 32.4‰) across 65...

Secondary organic aerosol (SOA) plays a critical role in sustained haze pollution megacities. Traditional observation of atmospheric aerosols usually analyzes the ambient (OA) but neglects SOA formation potential (SOAFP) precursors remaining air. Knowledge on SOAFP is still limited, especially megacities suffering from frequent haze. In this study, air urban Beijing was characterized at different levels based two-year field using an oxidation flow reactor (OFR) system. Both OA and increased...

Nitrates formed on mineral dust through heterogeneous reactions in high NOx areas can undergo photolysis to regenerate and potentially interfere the photochemistry downwind low areas. However, little is known about such renoxification processes. In this study, of various nitrates different oxides was comprehensively investigated a flow reactor situ diffuse reflectance Fourier-transform infrared spectroscopy (in DRIFTS). TiO2 found much more reactive than Al2O3 SiO2 with both NO2 HONO as two...

China is facing dual pressures to reduce both PM2.5 and O3 pollution, the crucial precursors of which are NOx VOCs. In our study, role in secondary organic aerosol (SOA, important constituent PM2.5) formation was examined 30 m3 indoor smog chamber. As revealed present level can obviously affect OH concentration volatility distribution gas-phase oxidation products thus SOA formation. Reducing NOx-sensitive regime inhibit (by 42%), resulting reduction capacity, suppresses 45%) by inhibiting O-...

Nitrous acid (HONO), a key precursor of hydroxyl radicals (OH), is one the factors affecting atmospheric chemistry and air quality. Currently, proposed sources HONO are not able to fully explain observed concentrations. In this study, comprehensive field observation was conducted in autumn 2021 urban Beijing. The box model using default Master Chemical Mechanism (MCM) unable reproduce concentrations with normalized mean bias (NMB) −92.8%. NMB improved −46.1% after inclusion seven additional...

Alkyl vinyl ethers are widely used as fuel additives. Despite this, their atmospheric chemistry and secondary organic aerosol (SOA) formation potentials still not well-known under complex pollution conditions. In this work, we examined the impact of SO2, relative humidity (RH), particle acidity on oxidation state (OSc) SOA from butyl ether (BVE) ozonolysis. Increasing SO2 concentration produced a notable promotion OSc due to significant increase in H2SO4 particles more highly oxidized...

Vehicular evaporative emissions make an increasing contribution to anthropogenic sources of volatile organic compounds (VOCs), thus contributing secondary aerosol (SOA) formation. However, few studies have been conducted on SOA formation from vehicle VOCs under complex pollution conditions with the coexistence NOx, SO2, and NH3. In this study, synergistic effects SO2 NH3 gasoline NOx were examined using a 30 m3 smog chamber aid series mass spectrometers. Compared systems involving or alone,...

The interplay between sulfur and iron holds significant importance in their atmospheric cycle, yet a complete understanding of coupling mechanism remains elusive. This investigation delves comprehensively into the evolution reactive oxygen species (ROS) during interfacial reactions involving dioxide (SO

HONO acts as a major OH source, playing vital role in secondary pollutant formation to deteriorate regional air quality. Strong unknown sources of daytime have been widely reported, which significantly limit our understanding radical cycling and atmospheric oxidation capacity. Here, we identify potential source originating from photoexcited phenyl organic nitrates formed during the photoreaction aromatics NOx. Significant (1.56–4.52 ppb) production is observed different kinds with NOx...

Regional transport of air pollutants is a serious challenge to outdoor O3 pollution control. Characterizing the by traditional quality models heavily relies on accurate precursor emission inventories, chemical reaction mechanisms, and meteorological factors. In this study, pollutant concentrations upwind cities were incorporated as features into random forest regression model (Traj-RF) investigate contribution regional local pollution. Hainan island was selected target area in due its being...

The activation of molecular oxygen on transition metal oxide surfaces plays a crucial role in atmospheric chemistry and heterogeneous catalysis; however, understanding the intricate mechanisms remains challenge. In this study, we elucidate for first time sulfur dioxide (SO2) enhancing manganese (γ-MnO2) surface, thereby facilitating oxidation nitric (NO) to nitrogen (NO2). theoretical calculation results further demonstrate that adsorbed SO2 formed sulfate can promote adsorption O2...

TiO2 is a widely used material in building coatings. Many studies have revealed that promotes the heterogeneous oxidation of SO2 and subsequent sulfate formation. However, whether how much contributes to gaseous H2SO4 new particle formation (NPF) still remains unclear. Herein, we 1 m3 quartz smog chamber investigate NPF presence TiO2. The experimental results indicated could greatly promote NPF. increases rate (J) growth due were quantified, promotion effect was attributed production H2SO4....

Chemical interactions between soot and NO2 are believed to play a significant role in the formation of HONO atmosphere. Despite extensive studies, present understanding how chemistry influences remains contentious due rapid deactivation surface reactive sites. In this study, we reveal novel mechanism that photoaging SO2 can notably accelerate reduction functionalized elemental carbon (EC) by rapidly removing hydroxyl functional groups. The reduced EC further drive continuous rejuvenation...

Soot, primarily composed of elemental carbon (EC) and organic (OC), is ubiquitous in PM

The heterogeneous oxidation of SO2 by NO2 has been extensively proposed as an important pathway sulfate production during haze events in China. However, the kinetics and mechanism on surface complex particles remain poorly understood. Here, we systematically explore reaction between diesel black carbon (DBC) under light irradiation. experimental results prove that DBC photochemistry can not only significantly promote reduction to produce HONO via transferring photoinduced electrons but also...

Nitrate photolysis is a vital process in secondary NOx release into the atmosphere. The heterogeneous oxidation of SO2 due to nitrate has been widely reported, while influence on rarely investigated. In this study, different substrates was investigated absence and presence SO2. NH4NO3 membrane without mineral oxides, NO, NO2, HONO, NH3 decreased by 17.1, 6.0, 12.6, 57.1% SO2, respectively. surface also exhibited an inhibitory effect production NOx, its reducibility acidic products, increase...

Secondary organic aerosol (SOA) is a significant component of atmospheric fine particulate matter (PM2.5), and their physicochemical properties can be significantly changed in the aging process. In this study, we used combination consisting smog chamber (SC) oxidation flow reactor (OFR) to investigate continuous process gas-phase intermediates SOA formed from photooxidation toluene, typical aromatic hydrocarbon. Our results showed that as OH exposure increased 2.6 × 1011 6.3 molecules cm-3 s...

Although there was significant advancement on polycyclic aromatic hydrocarbon (PAH) formation, current mechanisms are still limited in providing an integrated and accurate scheme of PAH yield combustion conditions; thus, a more detailed comprehensive understanding is necessary. This work provides systematic investigation growth by phenylacetylene addition. A combination the density functional theory (DFT/B3LYP/6-311+G(d,p)) complete basis set method (CBS-QB3) utilized to calculate potential...