scholarly journals Multiphase MCM/CAPRAMmodeling of formation and processing of secondary aerosol constituents observed at the Mt. Tai summer campaign 2014

2019 ◽  
Author(s):  
Yanhong Zhu ◽  
Andreas Tilgner ◽  
Erik Hans Hoffmann ◽  
Hartmut Herrmann ◽  
Kimitaka Kawamura ◽  
...  
Keyword(s):  
Oxalic Acid ◽  
Aqueous Phase ◽  
Glyoxylic Acid ◽  
Formation Mechanisms ◽  
Major Pathway ◽  
Voc Emissions ◽  
Secondary Aerosol ◽  
Model Studies ◽  
Huge Impact ◽  
Sensitivity Studies

Abstract. Despite the high abundance of secondary aerosols in the atmosphere, their formation mechanisms remain poorly understood. In this study, MCM/CAPRAM mechanism is 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 North 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 sub-urban oxidants budget. The modeled maximum gas-phase concentrations of OH radical are 3.2 × 106 molecules cm−3 and 3.5 × 106 molecules cm−3 in simulations with and without cloud passages in the air parcel, respectively. Different to 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 to 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 at daytime. The major pathway is aqueous-phase N2O5 hydrolysis, with a contribution of 72 % when cloud passages are considered and 70 % when 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 VOC emissions have a huge impact on the concentrations of modeled secondary aerosol compounds. Increasing the VOC emissions by a factor of two 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.

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.

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.

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 Oxidation of Glyoxylic Acid to Oxalic Acid by Glycolic Acid Oxidase

1961 ◽  
Vol 236 (5) ◽  
pp. 1280-1284
Author(s):  
K.E. Richardson ◽  
N.E. Tolbert
Keyword(s):  
Oxalic Acid ◽  
Glycolic Acid ◽  
Glyoxylic Acid ◽  
Acid Oxidase

Oxidation of substituted aromatic hydrocarbons in the tropospheric aqueous phase: kinetic mechanism development and modelling

2018 ◽  
Vol 20 (16) ◽  
pp. 10960-10977 ◽  
Author(s):  
Erik H. Hoffmann ◽  
Andreas Tilgner ◽  
Ralf Wolke ◽  
Olaf Böge ◽  
Arno Walter ◽  
...  
Keyword(s):  
Aqueous Phase ◽  
Aromatic Hydrocarbons ◽  
Aromatic Compounds ◽  
Kinetic Data ◽  
Kinetic Mechanism ◽  
Detailed Model ◽  
Model Studies ◽  
Phase Chemistry

An aqueous-phase chemistry mechanism for the oxidation of aromatic compounds in the atmosphere is developed based on available kinetic data. Detailed model studies successfully describe the oxidation and functionalization of monoaromatic compounds in the atmosphere.

scholarly journals Properties of aerosols and formation mechanisms over southern China during the monsoon season

2016 ◽  
Author(s):  
Weihua Chen ◽  
Xuemei Wang ◽  
Jason Blake Cohen ◽  
Shengzhen Zhou ◽  
Zhisheng Zhang ◽  
...  
Keyword(s):  
Aqueous Phase ◽  
Atmospheric Aerosols ◽  
Transport Model ◽  
Atmospheric Transport ◽  
Southern China ◽  
Monsoon Season ◽  
Sea Salt ◽  
Urban Site ◽  
Chemical Components ◽  
Formation Mechanisms

Abstract. Measurements of size-resolved aerosols from 0.25 to 18 μm were conducted at three sites (urban, suburban and background sites) and used in tandem with an atmospheric transport model to study the size distribution and formation of atmospheric aerosols in southern China during the monsoon season (May–June) in 2010. The mass distribution showed the majority of chemical components were found in the smaller size bins (< 2.5 μm). Sulfate, was found to be strongly correlated with aerosol water, and anti-correlated with atmospheric SO2, hinting at aqueous-phase reactions being the main formation pathway. Nitrate was the only major species that showed a bi-modal distribution at the urban site, and was dominated by the coarse mode in the other two sites, suggesting that an important component of nitrate formation is chloride depletion of sea salt transported from the South China Sea. In addition to these aqueous-phase reactions and interactions with sea salt aerosols, new particle formation, chemical aging, and long-range transport from upwind urban or biomass burning regions were also found to be important in at least some of the sights on some of the days. This work therefore summarizes the different mechanisms that significantly impact the aerosol chemical composition during the Monsoon over southern China.

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.

Modelling the Tropospheric Multiphase Chemistry of Biomass Burning Trace Compounds Using the Chemical Aqueous Phase Radical Mechanism (CAPRAM)

2021 ◽  
Author(s):  
Lin He ◽  
Erik Hans Hoffmann ◽  
Andreas Tilgner ◽  
Hartmut Herrmann
Keyword(s):  
Aqueous Phase ◽  
Biomass Burning ◽  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Laser Flash ◽  
Radical Mechanism ◽  
Aerosol Formation ◽  
Detailed Model ◽  
Model Studies ◽  
Trace Species

&lt;p&gt;Biomass burning (BB) is a significant contributor to air pollution on global, regional and local scale with impacts on air quality, public health and climate. Anhydrosugars (levoglucosan, mannosan and galactocan) and methoxyphenols (guaiacol, creosol, etc.) are important tracer compounds emitted through biomass burning. Once emitted, they can undergo complex multiphase chemistry in the atmosphere contributing to secondary organic aerosol formation. However, their chemical multiphase processing is not yet well understood and investigated by models. Therefore, the present study aimed at a better understanding of the multiphase chemistry of these BB trace species by means of detailed model studies with a new developed detailed chemical CAPRAM biomass burning module (CAPRAM-BB). This module was developed based on the kinetic data from the laser flash photolysis measurements in our lab at TROPOS and other literature studies. The developed CAPRAM-BB module includes 2991 reactions (thereof 9 phase transfers and 2982 aqueous-phase reactions). By coupling with the multiphase chemistry mechanism MCMv3.2/CAPRAM4.0 and the extended CAPRAM aromatics (CAPRAM-AM1.0) and halogen modules (CAPRAM-HM3.0), it is being applied for some residential wood burning cases in Europe and wildfire cases in the US. Our model results show that the BB chemistry could significantly affect the budgets of important atmospheric oxidants such as H&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;2&lt;/sub&gt; and HONO, and contribute to the SOA formation especially the fraction of brown carbon and substituted organic acids.&lt;/p&gt;

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