Summertime and wintertime atmospheric processes of secondary aerosol in Beijing

2020 ◽  
Author(s):  
Jing Duan ◽  
Rujin Huang ◽  
Chunshui Lin ◽  
Haiyan Ni ◽  
Meng Wang
Keyword(s):  
Aqueous Phase ◽  
Liquid Water ◽  
Fine Particles ◽  
Photochemical Oxidation ◽  
Formation Mechanisms ◽  
Phase Reaction ◽  
Aerosol Formation ◽  
Secondary Aerosol ◽  
Atmospheric Processes ◽  
Sulfate Formation

<p>Secondary aerosol constitutes a large fraction of fine particles in urban air of China. However, its formation mechanisms and atmospheric processes remain largely uncertain despite considerable studies in recent years. To elucidate the seasonal variations of fine particles composition and secondary aerosol formation, an Aerodyne quadrupole aerosol chemical speciation monitor (Q-ACSM) combined with other online instruments were used to characterize the submicron particulate matter (diameter < 1 μm, PM<sub>1</sub>) in Beijing during summer and winter 2015. Our results suggest that the photochemical oxidation was the major pathway for sulfate formation during summer, whereas aqueous-phase reaction became an important process for sulfate formation during winter. High concentration of nitrate (17% of the PM<sub>1</sub> mass) was found during winter explained by enhanced gas-to-particle partitioning at low temperature, while high nitrate concentration (19%) was also observed under the conditions of high relative humidity (RH) during summer likely due to the hydrophilic property of NH<sub>4</sub>NO<sub>3</sub> and hydrolysis of N<sub>2</sub>O<sub>5</sub>. As for SOA formation, photochemical oxidation perhaps played an important role for summertime oxygenated OA (OOA) formation and wintertime less oxidized OOA (LO-OOA) formation. The wintertime more oxidized OOA (MO-OOA) showed a good correlation with aerosol liquid water content (ALWC), indicating more important contribution of aqueous-phase processing than photochemical production to MO-OOA. Meanwhile, the dependence of LO-OOA and the mass ratio of LO-OOA to MO-OOA on atmospheric oxidative tracer (i.e., O<sub>x</sub>) both degraded when RH were greater than 60%, suggesting that RH or aerosol liquid water may also affect the LO-OOA formation.</p>

scholarly journals Summertime and wintertime atmospheric processes of secondary aerosol in Beijing

2020 ◽  
Vol 20 (6) ◽  
pp. 3793-3807 ◽  
Author(s):  
Jing Duan ◽  
Ru-Jin Huang ◽  
Yongjie Li ◽  
Qi Chen ◽  
Yan Zheng ◽  
...  
Keyword(s):  
Aqueous Phase ◽  
Liquid Water ◽  
Fine Particles ◽  
Photochemical Oxidation ◽  
Formation Mechanisms ◽  
Phase Reaction ◽  
Aerosol Formation ◽  
Secondary Aerosol ◽  
Atmospheric Processes ◽  
Sulfate Formation

Abstract. Secondary aerosol constitutes a large fraction of fine particles in urban air of China. However, its formation mechanisms and atmospheric processes remain largely uncertain despite considerable study in recent years. To elucidate the seasonal variations in fine-particle composition and secondary aerosol formation, an Aerodyne quadrupole aerosol chemical speciation monitor (Q-ACSM), combined with other online instruments, was used to characterize the sub-micrometer particulate matter (diameter < 1 µm, PM1) in Beijing during summer and winter 2015. Our results suggest that photochemical oxidation was the major pathway for sulfate formation during summer, whereas aqueous-phase reaction became an important process for sulfate formation during winter. High concentrations of nitrate (17 % of the PM1 mass) were found during winter, explained by enhanced gas-to-particle partitioning at low temperature, while high nitrate concentrations (19 %) were also observed under the conditions of high relative humidity (RH) during summer, likely due to the hydrophilic property of NH4NO3 and hydrolysis of N2O5. As for organic aerosol (OA) sources, secondary OA (SOA) dominated the OA mass (74 %) during summer, while the SOA contribution decreased to 39 % during winter due to enhanced primary emissions in the heating season. In terms of the SOA formation, photochemical oxidation perhaps played an important role for summertime oxygenated OA (OOA) formation and less-oxidized wintertime OOA (LO-OOA) formation. The wintertime more-oxidized OOA (MO-OOA) showed a good correlation with aerosol liquid water content (ALWC), indicating a more important contribution of aqueous-phase processing over photochemical production to MO-OOA. Meanwhile, the dependence of LO-OOA and the mass ratio of LO-OOA to MO-OOA on atmospheric oxidative tracer (i.e., Ox) both degraded when RH was greater than 60 %, suggesting that RH or aerosol liquid water may also affect LO-OOA formation.

scholarly journals Summertime and wintertime atmospheric processes of secondary aerosol in Beijing

2019 ◽  
Author(s):  
Jing Duan ◽  
Ru-Jin Huang ◽  
Yongjie Li ◽  
Qi Chen ◽  
Yan Zheng ◽  
...  
Keyword(s):  
Particulate Matter ◽  
Seasonal Variations ◽  
Chemical Speciation ◽  
Fine Particles ◽  
Large Fraction ◽  
Formation Mechanisms ◽  
Urban Air ◽  
Aerosol Formation ◽  
Secondary Aerosol ◽  
Atmospheric Processes

Abstract. Secondary aerosol constitutes a large fraction of fine particles in urban air of China. However, its formation mechanisms and atmospheric processes remain largely uncertain despite considerable studies in recent years. To elucidate the seasonal variations of fine particles composition and secondary aerosol formation, an Aerodyne quadrupole aerosol chemical speciation monitor (Q-ACSM) combined with other online instruments were used to characterize the submicron particulate matter (diameter 

scholarly journals Distinctions in source regions and formation mechanisms of secondary aerosol in Beijing from summer to winter

2019 ◽  
Vol 19 (15) ◽  
pp. 10319-10334 ◽  
Author(s):  
Jing Duan ◽  
Ru-Jin Huang ◽  
Chunshui Lin ◽  
Wenting Dai ◽  
Meng Wang ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Aqueous Phase ◽  
Regional Scale ◽  
Late Summer ◽  
Photochemical Oxidation ◽  
Formation Mechanisms ◽  
Early Winter ◽  
Secondary Aerosol ◽  
Haze Pollution ◽  
Sulfate Formation

Abstract. To investigate the sources and evolution of haze pollution in different seasons, long-term (from 15 August to 4 December 2015) variations in chemical composition of PM1 were characterized in Beijing, China. Positive matrix factorization (PMF) analysis with a multi-linear engine (ME-2) resolved three primary and two secondary organic aerosol (OA) sources, including hydrocarbon-like OA (HOA), cooking OA (COA), coal combustion OA (CCOA), local secondary OA (LSOA) and regional SOA (RSOA). The sulfate source region analysis implies that sulfate was mainly transported at a large regional scale in late summer, while local and/or nearby sulfate formation may be more important in winter. Meanwhile, distinctly different correlations between sulfate and RSOA or LSOA (i.e., better correlation with RSOA in late summer, similar correlations with RSOA and LSOA in autumn, and close correlation with LSOA in early winter) confirmed the regional characteristic of RSOA and local property of LSOA. Secondary aerosol species including secondary inorganic aerosol (SIA – sulfate, nitrate, and ammonium) and SOA (LSOA and RSOA) dominated PM1 during all three seasons. In particular, SOA contributed 46 % to total PM1 (with 31 % as RSOA) in late summer, whereas SIA contributed 41 % and 45 % to total PM1 in autumn and early winter, respectively. Enhanced contributions of secondary species (66 %–76 % of PM1) were also observed in pollution episodes during all three seasons, further emphasizing the importance of secondary formation processes in haze pollution in Beijing. Combining chemical composition and meteorological data, our analyses suggest that both photochemical oxidation and aqueous-phase processing played important roles in SOA formation during all three seasons, while for sulfate formation, gas-phase photochemical oxidation was the major pathway in late summer, aqueous-phase reactions were more responsible during early winter and both processes had contributions during autumn.

scholarly journals Distinctions in source regions and formation mechanisms of secondary aerosol in Beijing from summer to winter

2019 ◽  
Author(s):  
Jing Duan ◽  
Ru-Jin Huang ◽  
Chunshui Lin ◽  
Wenting Dai ◽  
Meng Wang ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Meteorological Data ◽  
Regional Scale ◽  
Late Summer ◽  
Photochemical Oxidation ◽  
Formation Mechanisms ◽  
Early Winter ◽  
Secondary Aerosol ◽  
Haze Pollution ◽  
Sulfate Formation

Abstract. To investigate the sources and evolution of haze pollution in different seasons, long-term (from 15 August to 4 December 2015) variations of chemical composition of PM1 were characterized in Beijing, China. Positive matrix factorization (PMF) analysis with multi-linear engine (ME-2) resolved three primary and two secondary OA sources, including hydrocarbon-like OA (HOA), cooking OA (COA), coal combustion OA (CCOA), local secondary OA (LSOA) and regional SOA (RSOA). Distinctly different correlations between RSOA and sulfate were found in our study, with tight correlation (R2 = 0.71) in late summer, decreased correlation (R2 = 0.62) in autumn and almost no correlation (R2 = 0.02) in early winter. This difference implies that sulfate was mainly transported at a large regional scale in late summer, while local and/or nearby sulfate formation may be more important in winter. Secondary aerosol species including SIA (sulfate, nitrate and ammonium) and SOA (LSOA and RSOA) dominated PM1 during all three seasons. In particular, SOA contributed 46 % to total PM1 (with 31 % as RSOA) in late summer, whereas SIA contributed 41 % and 45 % to total PM1 in autumn and early winter, respectively. Enhanced contributions of secondary species (66–76 % of PM1) were also observed in pollution episodes during all three seasons, further emphasizing the importance of secondary formation processes in haze pollution in Beijing. Combining chemical composition and meteorological data, our analyses suggest that photochemical oxidation dominated SOA formation during all three seasons, while for sulfate formation, gas-phase photochemical oxidation was the major pathway in late summer and heterogeneous processes were likely more important in autumn and early winter.

scholarly journals SO<sub>2</sub> and NH<sub>3</sub> emissions enhance organosulfur compounds and fine particles formation from the photooxidation of a typical aromatic hydrocarbon

2021 ◽  
Author(s):  
Zhaomin Yang ◽  
Li Xu ◽  
Narcisse T. Tsona ◽  
Jianlong Li ◽  
Xin Luo ◽  
...  
Keyword(s):  
Fine Particles ◽  
Heterogeneous Reaction ◽  
Oxidation Mechanism ◽  
Unknown Origin ◽  
Formation Mechanisms ◽  
Chemical Compositions ◽  
Organosulfur Compounds ◽  
Aerosol Formation ◽  
Particle Volume ◽  
Secondary Aerosol

Abstract. Although atmospheric SO2 and NH3 levels can affect secondary aerosol formation, the influenced extent of their impact and their detailed driving mechanisms are not well understood. The focus of the present study is to examine the chemical compositions and formation mechanisms of secondary organic aerosols (SOA) from 1,2,4-trimethylbenzene (TMB) photooxidation influenced by SO2 and/or NH3. Here, we showed that SO2 emission could considerably enhance aerosol particle formation due to SO2-induced sulfates generation and acid-catalyzed heterogeneous reaction. Orbitrap mass spectrometry (MS) measurements revealed the generation of not only typical TMB products but also hitherto unidentified organosulfates (OSs) in SO2-added experiments. The OSs designated as unknown origin in earlier field measurements were also detected in TMB SOA, indicating that atmospheric OSs might be also originated from TMB photooxidation. For NH3-involved experiments, results demonstrated a positive correlation between NH3 levels and particle volume as well as number concentrations. The effects of NH3 on SOA composition was slight under SO2-free conditions but stronger in the presence of SO2. A series of multifunctional products with carbonyl, alcohols, and nitrate functional groups were tentatively characterized in NH3-involved experiments based on infrared spectra and HRMS analysis. Plausible formation pathways were proposed for detected products in the particle-phase. The volatility distributions of products, estimated using parameterization methods, suggested that the detected products gradually condense onto the nucleation particles to contribute to aerosol formation and growth. Our results suggest that strict control of SO2 and NH3 emissions might remarkably reduce organosulfates and secondary aerosol burden in the atmosphere. Updating the aromatic oxidation mechanism in models could result in more accurate treatment of particles formation for urban regions with considerable SO2, NH3, and aromatics emissions.

scholarly journals SO<sub>2</sub> and NH<sub>3</sub> emissions enhance organosulfur compounds and fine particle formation from the photooxidation of a typical aromatic hydrocarbon

2021 ◽  
Vol 21 (10) ◽  
pp. 7963-7981
Author(s):  
Zhaomin Yang ◽  
Li Xu ◽  
Narcisse T. Tsona ◽  
Jianlong Li ◽  
Xin Luo ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Oxidation Mechanism ◽  
Particle Formation ◽  
Urban Atmosphere ◽  
Mass Spectrometry Analysis ◽  
Formation Mechanisms ◽  
Chemical Compositions ◽  
Organosulfur Compounds ◽  
Aerosol Formation ◽  
Secondary Aerosol

Abstract. Aromatic hydrocarbons can dominate the volatile organic compound budget in the urban atmosphere. Among them, 1,2,4-trimethylbenzene (TMB), mainly emitted from solvent use, is one of the most important secondary organic aerosol (SOA) precursors. Although atmospheric SO2 and NH3 levels can affect secondary aerosol formation, the influenced extent of their impact and their detailed driving mechanisms are not well understood. The focus of the present study is to examine the chemical compositions and formation mechanisms of SOA from TMB photooxidation influenced by SO2 and/or NH3. Here, we show that SO2 emission could considerably enhance aerosol particle formation due to SO2-induced sulfate generation and acid-catalyzed heterogeneous reactions. Orbitrap mass spectrometry measurements revealed the generation of not only typical TMB products but also hitherto unidentified organosulfates (OSs) in SO2-added experiments. The OSs designated as being of unknown origin in earlier field measurements were also detected in TMB SOA, indicating that atmospheric OSs might also be originated from TMB photooxidation. For NH3-involved experiments, results demonstrated a positive correlation between NH3 levels and particle volume as well as number concentrations. The effects of NH3 on SOA composition were slight under SO2-free conditions but stronger in the presence of SO2. A series of multifunctional products with carbonyl, alcohols, and nitrate functional groups were tentatively characterized in NH3-involved experiments based on infrared spectra and mass spectrometry analysis. Plausible formation pathways were proposed for detected products in the particle phase. The volatility distributions of products, estimated using parameterization methods, suggested that the detected products gradually condense onto the nucleation particles to contribute to aerosol formation and growth. Our results suggest that strict control of SO2 and NH3 emissions might remarkably reduce organosulfates and secondary aerosol burden in the atmosphere. Updating the aromatic oxidation mechanism in models could result in more accurate treatment of particle formation for urban regions with considerable SO2, NH3, and aromatics emissions.

scholarly journals Heterogeneous sulfate aerosol formation mechanisms during wintertime Chinese haze events: Air quality model assessment using observations of sulfate oxygen isotopes in Beijing

2019 ◽  
Author(s):  
Jingyuan Shao ◽  
Qianjie Chen ◽  
Yuxuan Wang ◽  
Xiao Lu ◽  
Pengzhen He ◽  
...  
Keyword(s):  
Air Quality ◽  
Oxygen Isotopes ◽  
Metal Ion ◽  
Transport Model ◽  
Formation Mechanisms ◽  
Model Assessment ◽  
Aerosol Formation ◽  
Air Quality Model ◽  
Sulfate Production ◽  
Sulfate Formation

Abstract. Air quality models have not been able to reproduce the magnitude of the observed concentrations of fine particulate matter (PM2.5) during wintertime Chinese haze events. The discrepancy has been at least partly attributed to low biases in modeled sulfate production rates due to the lack of heterogeneous sulfate production on aerosols in the models. In this study, we explicitly implement four heterogeneous sulfate formation mechanisms into a regional chemical transport model, in addition to gas-phase and in-cloud sulfate production. We compare the model results with observations of sulfate concentrations and oxygen isotopes (Δ17O(SO42−)) in the winter of 2014–2015, the latter of which is highly sensitive to the relative importance of different sulfate production mechanisms. Model results suggest that heterogeneous sulfate production on aerosols accounts for about 20 % of sulfate production in clean and polluted conditions, partially reducing the modeled low bias in sulfate concentrations. Model sensitivity studies in comparison with the Δ17O(SO42−) observations suggest that heterogeneous sulfate formation is dominated by transition metal ion catalyzed oxidation of SO2.

scholarly journals Characterization of aerosol and cloud water at a mountain site during WACS 2010: secondary organic aerosol formation through oxidative cloud processing

2012 ◽  
Vol 12 (2) ◽  
pp. 6019-6047 ◽  
Author(s):  
A. K. Y. Lee ◽  
K. L. Hayden ◽  
P. Herckes ◽  
W. R. Leaitch ◽  
J. Liggio ◽  
...  
Keyword(s):  
Aqueous Phase ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Cloud Water ◽  
Water Soluble ◽  
Photochemical Oxidation ◽  
Aerosol Formation ◽  
Aerosol Mass ◽  
Dissolved Organics ◽  
Organic Spectra

Abstract. The water-soluble fractions of aerosol samples and cloud water collected during Whistler Aerosol and Cloud Study (WACS 2010) were analyzed using an Aerodyne aerosol mass spectrometer (AMS). This is the first study to report AMS organic spectra of re-aerosolized cloud water, and to make direct comparison between the AMS spectra of cloud water and aerosol samples collected at the same location. In general, the aerosol and cloud organic spectra were very similar, indicating that the cloud water organics likely originated from secondary organic aerosol (SOA) formed nearby. By using a photochemical reactor to oxidize both aerosol filter extracts and cloud water, we find evidence that fragmentation of aerosol water-soluble organics increases their volatility during oxidation. By contrast, enhancement of AMS-measurable organic mass by up to 30% was observed during aqueous-phase photochemical oxidation of cloud water organics. We propose that additional SOA material was produced by functionalizing dissolved organics via OH oxidation, where these dissolved organics are sufficiently volatile that they are not usually part of the aerosol. This work points out that water-soluble organic compounds of intermediate volatility (IVOC), such as cis-pinonic acid, produced via gas-phase oxidation of monoterpenes, can be important aqueous-phase SOA precursors in a biogenic-rich environment.

scholarly journals Traffic-originated nanocluster emission exceeds H<sub>2</sub>SO<sub>4</sub>-driven photochemical new particle formation in an urban area

2020 ◽  
Vol 20 (1) ◽  
pp. 1-13 ◽  
Author(s):  
Miska Olin ◽  
Heino Kuuluvainen ◽  
Minna Aurela ◽  
Joni Kalliokoski ◽  
Niina Kuittinen ◽  
...  
Keyword(s):  
Solar Radiation ◽  
Particle Formation ◽  
Urban Environments ◽  
Urban Traffic ◽  
Photochemical Oxidation ◽  
Traffic Density ◽  
Formation Mechanisms ◽  
New Particle Formation ◽  
Aerosol Formation ◽  
Vehicle Exhaust

Abstract. Elevated ambient concentrations of sub-3 nm particles (nanocluster aerosol, NCA) are generally related to atmospheric new particle formation events, usually linked with gaseous sulfuric acid (H2SO4) produced via photochemical oxidation of sulfur dioxide. According to our measurement results of H2SO4 and NCA concentrations, traffic density, and solar irradiance at an urban traffic site in Helsinki, Finland, the view of aerosol formation in traffic-influenced environments is updated by presenting two separate and independent pathways of traffic affecting the atmospheric NCA concentrations: by acting as a direct nanocluster source and by influencing the production of H2SO4. As traffic density in many areas is generally correlated with solar radiation, it is likely that the influence of traffic-related nanoclusters has been hidden in the diurnal variation and is thus underestimated because new particle formation events also follow the diurnal cycle of sunlight. Urban aerosol formation studies should, therefore, be updated to include the proposed formation mechanisms. The formation of H2SO4 in urban environments is here separated into two routes: primary H2SO4 is formed in hot vehicle exhaust and is converted rapidly to the particle phase; secondary H2SO4 results from the combined effect of emitted gaseous precursors and available solar radiation. A rough estimation demonstrates that ∼85 % of the total NCA and ∼68 % of the total H2SO4 in urban air at noontime at the measurement site are contributed by traffic, indicating the importance of traffic emissions.

scholarly journals Multiphase MCM–CAPRAM modeling of the formation and processing of secondary aerosol constituents observed during the Mt. Tai summer campaign in 2014

2020 ◽  
Vol 20 (11) ◽  
pp. 6725-6747 ◽  
Author(s):  
Yanhong Zhu ◽  
Andreas Tilgner ◽  
Erik Hans Hoffmann ◽  
Hartmut Herrmann ◽  
Kimitaka Kawamura ◽  
...  
Keyword(s):  
Oxalic Acid ◽  
Aqueous Phase ◽  
Glyoxylic Acid ◽  
Northern China ◽  
Chemical Mechanism ◽  
Radical Mechanism ◽  
Formation Mechanisms ◽  
Major Pathway ◽  
Voc Emissions ◽  
Secondary Aerosol

Abstract. Despite the high abundance of secondary aerosols in the atmosphere, their formation mechanisms remain poorly understood. In this study, the Master Chemical Mechanism (MCM) and the Chemical Aqueous-Phase Radical Mechanism (CAPRAM) are used to investigate the multiphase formation and processing of secondary aerosol constituents during the advection of air masses towards the measurement site of Mt. Tai in northern China. Trajectories with and without chemical–cloud interaction are modeled. Modeled radical and non-radical concentrations demonstrate that the summit of Mt. Tai, with an altitude of ∼1.5 km a.m.s.l., is characterized by a suburban oxidants budget. The modeled maximum gas-phase concentrations of the OH radical are 3.2×106 and 3.5×106 molec. cm−3 in simulations with and without cloud passages in the air parcel, respectively. In contrast with previous studies at Mt. Tai, this study has modeled chemical formation processes of secondary aerosol constituents under day vs. night and cloud vs. non-cloud cases along the trajectories towards Mt. Tai in detail. The model studies show that sulfate is mainly produced in simulations where the air parcel is influenced by cloud chemistry. Under the simulated conditions, the aqueous reaction of HSO3- with H2O2 is the major contributor to sulfate formation, contributing 67 % and 60 % in the simulations with cloud and non-cloud passages, respectively. The modeled nitrate formation is higher at nighttime than during daytime. The major pathway is aqueous-phase N2O5 hydrolysis, with a contribution of 72 % when cloud passages are considered and 70 % when they are not. Secondary organic aerosol (SOA) compounds, e.g., glyoxylic, oxalic, pyruvic and malonic acid, are found to be mostly produced from the aqueous oxidations of hydrated glyoxal, hydrated glyoxylic acid, nitro-2-oxopropanoate and hydrated 3-oxopropanoic acid, respectively. Sensitivity studies reveal that gaseous volatile organic compound (VOC) emissions have a huge impact on the concentrations of modeled secondary aerosol compounds. Increasing the VOC emissions by a factor of 2 leads to linearly increased concentrations of the corresponding SOA compounds. Studies using the relative incremental reactivity (RIR) method have identified isoprene, 1,3-butadiene and toluene as the key precursors for glyoxylic and oxalic acid, but only isoprene is found to be a key precursor for pyruvic acid. Additionally, the model investigations demonstrate that an increased aerosol partitioning of glyoxal can play an important role in the aqueous-phase formation of glyoxylic and oxalic acid. Overall, the present study is the first that provides more detailed insights in the formation pathways of secondary aerosol constituents at Mt. Tai and clearly emphasizes the importance of aqueous-phase chemical processes on the production of multifunctional carboxylic acids.

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