scholarly journals Contrasting effects of secondary organic aerosol formations on organic aerosol hygroscopicity

2021 ◽  
Author(s):  
Ye Kuang ◽  
Shan Huang ◽  
Biao Xue ◽  
Biao Luo ◽  
Qicong Song ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Climate Models ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Pearl River Delta Region ◽  
Oxidation Level ◽  
Positive Effects ◽  
Aerosol Mass ◽  
Mass Fractions ◽  
Aerosol Hygroscopicity

Abstract. Water uptake abilities of organic aerosol under sub-saturated conditions play critical roles in direct aerosol radiative effects and atmospheric chemistry, however, field characterizations of organic aerosol hygroscopicity parameter κOA under sub-saturated conditions remain limited. In this study, a field campaign was conducted to characterize κOA at relative humidity of 80 % with hourly time resolution for the first time in the Pearl River Delta region of China. Observation results show that during this campaign secondary organic aerosol (SOA) dominated total organic aerosol mass (mass fraction >70 % on average), which provides us a unique opportunity to investigate influences of SOA formation on κOA. Results demonstrate that the commonly used organic aerosol oxidation level parameter O / C was weakly correlated with κOA and failed in describing the variations of κOA. However, the variations in κOA were well reproduced by mass fractions of organic aerosol factor resolved based on aerosol mass spectrometer measurements. The more oxygenated organic aerosol (MOOA) factor, exhibiting the highest average O / C (~1) among all organic aerosol factors, was the most important factor driving the increase of κOA and was commonly associated with regional air masses. The less oxygenated organic aerosol (LOOA, average O / C of 0.72) factor, revealed strong daytime production, exerting negative effects on κOA. Surprisingly, the aged biomass burning organic aerosol (aBBOA) factor also formed quickly during daytime and shared a similar diurnal pattern with LOOA, but had much lower O / C (0.39) and had positive effects on κOA. The correlation coefficient between κOA and mass fractions of aBBOA and MOOA in total organic aerosol mass reached above 0.8. The contrasting effects of LOOA and aBBOA formation on κOA demonstrates that volatile organic compound (VOC) precursors from diverse sources and different SOA formation processes may result in SOA with different chemical composition, functional properties as well as microphysical structure, consequently, exert distinct influences on κOA and render single oxidation level parameters (such as O / C) unable to capture those differences. Aside from that, distinct effects of aBBOA on κOA was observed during different episodes, suggesting that the hygroscopicity of SOA associated with similar sources might also differ much under different emission and atmospheric conditions. Overall, these results highlight that it is imperative to conduct more researches on κOA characterization under different meteorological and source conditions, and examine its relationship with VOC precursor profiles and formation pathways to formulate a better characterization and develop more appropriate parameterization approaches in chemical and climate models.

scholarly journals Contrasting effects of secondary organic aerosol formations on organic aerosol hygroscopicity

2021 ◽  
Vol 21 (13) ◽  
pp. 10375-10391
Author(s):  
Ye Kuang ◽  
Shan Huang ◽  
Biao Xue ◽  
Biao Luo ◽  
Qicong Song ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Climate Models ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Pearl River Delta Region ◽  
Oxidation Level ◽  
Positive Effects ◽  
Aerosol Mass ◽  
Mass Fractions ◽  
Aerosol Hygroscopicity

Abstract. Water uptake abilities of organic aerosol under sub-saturated conditions play critical roles in direct aerosol radiative effects and atmospheric chemistry; however, field characterizations of the organic aerosol hygroscopicity parameter κOA under sub-saturated conditions remain limited. In this study, a field campaign was conducted to characterize κOA at a relative humidity of 80 % with hourly time resolution for the first time in the Pearl River Delta region of China. Observation results show that, during this campaign, secondary organic aerosol (SOA) dominated total organic aerosol mass (mass fraction > 70 % on average), which provides a unique opportunity to investigate influences of SOA formation on κOA. Results demonstrate that the commonly used organic aerosol oxidation level parameter O/C was weakly correlated with κOA and failed to describe the variations in κOA. However, the variations in κOA were well reproduced by mass fractions of organic aerosol factor resolved based on aerosol mass spectrometer measurements. The more oxygenated organic aerosol (MOOA) factor, exhibiting the highest average O/C (∼ 1) among all organic aerosol factors, was the most important factor driving the increase in κOA and was commonly associated with regional air masses. The less oxygenated organic aerosol (LOOA; average O/C of 0.72) factor revealed strong daytime production, exerting negative effects on κOA. Surprisingly, the aged biomass burning organic aerosol (aBBOA) factor also formed quickly during daytime and shared a similar diurnal pattern with LOOA but had much lower O/C (0.39) and had positive effects on κOA. The correlation coefficient between κOA and mass fractions of aBBOA and MOOA in total organic aerosol mass reached above 0.8. The contrasting effects of LOOA and aBBOA formation on κOA demonstrate that volatile organic compound (VOC) precursors from diverse sources and different SOA formation processes may result in SOA with different chemical composition, functional properties and microphysical structure, consequently exerting distinct influences on κOA and rendering single oxidation level parameters (such as O/C) unable to capture those differences. Aside from that, distinct effects of aBBOA on κOA were observed during different episodes, suggesting that the hygroscopicity of SOA associated with similar sources might also differ much under different emission and atmospheric conditions. Overall, these results highlight that it is imperative to conduct more research on κOA characterization under different meteorological and source conditions and examine its relationship with VOC precursor profiles and formation pathways to formulate a better characterization and develop more appropriate parameterization approaches in chemical and climate models.

scholarly journals Simulating secondary organic aerosol from missing diesel-related intermediate-volatility organic compound emissions during the Clean Air for London (ClearfLo) campaign

2016 ◽  
Author(s):  
R. Ots ◽  
D. E. Young ◽  
M. Vieno ◽  
L. Xu ◽  
R. E. Dunmore ◽  
...  
Keyword(s):  
Organic Compound ◽  
Atmospheric Chemistry ◽  
Secondary Organic Aerosol ◽  
Transport Model ◽  
Field Measurements ◽  
Organic Aerosol ◽  
Total Particulate Matter ◽  
Aerosol Mass ◽  
Clean Air ◽  
The Uk

Abstract. We present high-resolution atmospheric chemistry transport model (ACTM) simulations of secondary organic aerosol (SOA) formation over the UK for 2012. Our simulations include additional diesel-related intermediate volatility organic compound (IVOC) emissions derived directly from comprehensive field measurements at an urban background site in London during the 2012 Clean Air for London (ClearfLo) campaign. Our IVOC emissions are added proportionally to VOC emissions, as opposed to proportionally to primary organic aerosol (POA) as has been done by previous ACTM studies seeking to simulate the effects of these missing emissions. Modelled concentrations are evaluated against hourly and daily measurements of organic aerosol (OA) components derived from aerosol mass spectrometer (AMS) measurements also made during the ClearfLo campaign at three sites in the London area. Good hourly performance in comparison to the measurements was shown, giving confidence in the SOA prediction skill of the ACTM system used. According to the model simulations, diesel-related IVOCs can explain on average ~30% of the annual SOA in and around London. Furthermore, the 90-th percentile of modelled daily SOA concentrations for the whole year is 3.8 μg m−3 (more than 40% of which is produced from the missing diesel precursors), constituting a notable addition to total particulate matter. More measurements of these precursors (currently not included in official emissions inventories) is recommended. During the period of concurrent measurements, SOA concentrations at the Detling rural background location east of London were greater than at the central London location. The model shows that this was caused by an intense pollution plume with a strong gradient of imported SOA passing over the rural location. This demonstrates the value of modelling for supporting the interpretation of measurements taken at different sites or for short durations.

scholarly journals A technique for the measurement of organic aerosol hygroscopicity, oxidation level, and volatility distributions

2017 ◽  
Vol 10 (12) ◽  
pp. 4865-4876 ◽  
Author(s):  
Kerrigan P. Cain ◽  
Spyros N. Pandis
Keyword(s):  
Cloud Condensation Nuclei ◽  
Organic Aerosol ◽  
Experimental Setup ◽  
Aerosol Mass Spectrometer ◽  
Oxidation Level ◽  
Aerosol Mass ◽  
Analysis Technique ◽  
Measurement And Analysis ◽  
High Volatility ◽  
Aerosol Hygroscopicity

Abstract. Hygroscopicity, oxidation level, and volatility are three crucial properties of organic pollutants. This study assesses the feasibility of a novel measurement and analysis technique to determine these properties and establish their relationship. The proposed experimental setup utilizes a cloud condensation nuclei (CCN) counter to quantify hygroscopic activity, an aerosol mass spectrometer to measure the oxidation level, and a thermodenuder to evaluate the volatility. The setup was first tested with secondary organic aerosol (SOA) formed from the ozonolysis of α-pinene. The results of the first experiments indicated that, for this system, the less volatile SOA contained species that had on average lower O : C ratios and hygroscopicities. In this SOA system, both low- and high-volatility components can have comparable oxidation levels and hygroscopicities. The method developed here can be used to provide valuable insights about the relationships among organic aerosol hygroscopicity, oxidation level, and volatility.

Parameterization of secondary organic aerosol mass fractions from smog chamber data

2008 ◽  
Vol 42 (10) ◽  
pp. 2276-2299 ◽  
Author(s):  
Charles O. Stanier ◽  
Neil Donahue ◽  
Spyros N. Pandis
Keyword(s):  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Smog Chamber ◽  
Aerosol Mass ◽  
Mass Fractions

scholarly journals A technique for the measurement of organic aerosol hygroscopicity, oxidation level, and volatility distributions

2017 ◽  
Author(s):  
Kerrigan P. Cain ◽  
Spyros N. Pandis
Keyword(s):  
Cloud Condensation Nuclei ◽  
Organic Aerosol ◽  
Experimental Setup ◽  
Aerosol Mass Spectrometer ◽  
Oxidation Level ◽  
Aerosol Mass ◽  
Analysis Technique ◽  
Measurement And Analysis ◽  
High Volatility ◽  
Aerosol Hygroscopicity

Abstract. Hygroscopicity, oxidation level, and volatility of organic pollutants are three crucial properties that determine their fate in the atmosphere. This study assesses the feasibility of a novel measurement and analysis technique to determine these properties of organic aerosol components at the same time and to establish their relationship. The proposed experimental setup utilizes a cloud condensation nuclei counter to quantify hygroscopic activity, an aerosol mass spectrometer to measure the oxidation level, and a thermodenuder to evaluate the volatility. The setup was first tested with secondary organic aerosol (SOA) formed from the ozonolysis of α-pinene. The results of the first experiments indicated that, for this system, the less volatile SOA contained species that had on average lower O : C ratios and hygroscopicities. In this SOA system, both low and high volatility components can have comparable oxidation levels and hygroscopicities. The method developed here can be used to provide valuable insights about the relationships among organic aerosol hygroscopicity, oxidation level, and volatility.

scholarly journals Tiny Particles with Big Impact on Global Climate

Eos ◽  
2017 ◽  
Vol 98 ◽  
Author(s):  
Manishkumar Shrivastava
Keyword(s):  
Atmospheric Chemistry ◽  
Climate Models ◽  
Secondary Organic Aerosol ◽  
Global Climate ◽  
Organic Aerosol

A recent paper in Reviews of Geophysics suggests that new understandings of secondary organic aerosol may require a rethinking of atmospheric chemistry-climate models.

scholarly journals Secondary organic aerosol formation from biomass burning emissions

2019 ◽  
Author(s):  
Christopher Y. Lim ◽  
David H. Hagan ◽  
Matthew M. Coggon ◽  
Abigail R. Koss ◽  
Kanako Sekimoto ◽  
...  
Keyword(s):  
Biomass Burning ◽  
Secondary Organic Aerosol ◽  
Total Concentration ◽  
Organic Aerosol ◽  
Oh Radicals ◽  
Aerosol Formation ◽  
Atmospheric Aging ◽  
Aerosol Mass ◽  
Photochemical Aging ◽  
Organic Gases

Abstract. Biomass burning is an important source of aerosol and trace gases to the atmosphere, but how these emissions change chemically during their lifetimes is not fully understood. As part of the Fire Influence on Regional and Global Environments Experiment (FIREX 2016), we investigated the effect of photochemical aging on biomass burning organic aerosol (BBOA), with a focus on fuels from the western United States. Emissions were sampled into a small (150 L) environmental chamber and photochemically aged via the addition of ozone and irradiation by 254 nm light. While some fraction of species undergoes photolysis, the vast majority of aging occurs via reaction with OH radicals, with total OH exposures corresponding to the equivalent of up to 10 days of atmospheric oxidation. For all fuels burned, large and rapid changes are seen in the ensemble chemical composition of BBOA, as measured by an aerosol mass spectrometer (AMS). Secondary organic aerosol (SOA) formation is seen for all aging experiments and continues to grow with increasing OH exposure, but the magnitude of the SOA formation is highly variable between experiments. This variability can be explained well by a combination of experiment-to-experiment differences in OH exposure and the total concentration of non-methane organic gases (NMOGs) in the chamber before oxidation, measured by PTR-ToF-MS (r2 values from 0.64 to 0.83). From this relationship, we calculate the fraction of carbon from biomass burning NMOGs that is converted to SOA as a function of equivalent atmospheric aging time, with carbon yields ranging from 24 ± 4 % after 6 hours to 56 ± 9 % after 4 days.

scholarly journals Particle-bound reactive oxygen species (PB-ROS) emissions and formation pathways in residential wood smoke under different combustion and aging conditions

2018 ◽  
Vol 18 (10) ◽  
pp. 6985-7000 ◽  
Author(s):  
Jun Zhou ◽  
Peter Zotter ◽  
Emily A. Bruns ◽  
Giulia Stefenelli ◽  
Deepika Bhattu ◽  
...  
Keyword(s):  
Reactive Oxygen Species ◽  
Regression Model ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Oxygen Species ◽  
Wood Combustion ◽  
Aerosol Mass ◽  
Combustion Emissions ◽  
Aging Conditions ◽  
Combustion Regimes

Abstract. Wood combustion emissions can induce oxidative stress in the human respiratory tract by reactive oxygen species (ROS) in the aerosol particles, which are emitted either directly or formed through oxidation in the atmosphere. To improve our understanding of the particle-bound ROS (PB-ROS) generation potential of wood combustion emissions, a suite of smog chamber (SC) and potential aerosol mass (PAM) chamber experiments were conducted under well-determined conditions for different combustion devices and technologies, different fuel types, operation methods, combustion regimes, combustion phases, and aging conditions. The PB-ROS content and the chemical properties of the aerosols were quantified by a novel ROS analyzer using the DCFH (2′,7′-dichlorofluorescin) assay and a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS). For all eight combustion devices tested, primary PB-ROS concentrations substantially increased upon aging. The level of primary and aged PB-ROS emission factors (EFROS) were dominated by the combustion device (within different combustion technologies) and to a greater extent by the combustion regimes: the variability within one device was much higher than the variability of EFROS from different devices. Aged EFROS under bad combustion conditions were ∼ 2–80 times higher than under optimum combustion conditions. EFROS from automatically operated combustion devices were on average 1 order of magnitude lower than those from manually operated devices, which indicates that automatic combustion devices operated at optimum conditions to achieve near-complete combustion should be employed to minimize PB-ROS emissions. The use of an electrostatic precipitator decreased the primary and aged ROS emissions by a factor of ∼ 1.5 which is however still within the burn-to-burn variability. The parameters controlling the PB-ROS formation in secondary organic aerosol were investigated by employing a regression model, including the fractions of the mass-to-charge ratios m∕z 44 and 43 in secondary organic aerosol (SOA; f44−SOA and f43−SOA), the OH exposure, and the total organic aerosol mass. The regression model results of the SC and PAM chamber aging experiments indicate that the PB-ROS content in SOA seems to increase with the SOA oxidation state, which initially increases with OH exposure and decreases with the additional partitioning of semi-volatile components with lower PB-ROS content at higher OA concentrations, while further aging seems to result in a decay of PB-ROS. The results and the special data analysis methods deployed in this study could provide a model for PB-ROS analysis of further wood or other combustion studies investigating different combustion conditions and aging methods.

scholarly journals Constraining condensed-phase formation kinetics of secondary organic aerosol components from isoprene epoxydiols

2016 ◽  
Vol 16 (3) ◽  
pp. 1245-1254 ◽  
Author(s):  
T. P. Riedel ◽  
Y.-H. Lin ◽  
Z. Zhang ◽  
K. Chu ◽  
J. A. Thornton ◽  
...  
Keyword(s):  
Aqueous Phase ◽  
Atmospheric Aerosols ◽  
Rate Constants ◽  
Reaction Rate ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Heterogeneous Reactions ◽  
Model Calculations ◽  
Reaction Rate Constants ◽  
Aerosol Mass

Abstract. Isomeric epoxydiols from isoprene photooxidation (IEPOX) have been shown to produce substantial amounts of secondary organic aerosol (SOA) mass and are therefore considered a major isoprene-derived SOA precursor. Heterogeneous reactions of IEPOX on atmospheric aerosols form various aerosol-phase components or "tracers" that contribute to the SOA mass burden. A limited number of the reaction rate constants for these acid-catalyzed aqueous-phase tracer formation reactions have been constrained through bulk laboratory measurements. We have designed a chemical box model with multiple experimental constraints to explicitly simulate gas- and aqueous-phase reactions during chamber experiments of SOA growth from IEPOX uptake onto acidic sulfate aerosol. The model is constrained by measurements of the IEPOX reactive uptake coefficient, IEPOX and aerosol chamber wall losses, chamber-measured aerosol mass and surface area concentrations, aerosol thermodynamic model calculations, and offline filter-based measurements of SOA tracers. By requiring the model output to match the SOA growth and offline filter measurements collected during the chamber experiments, we derive estimates of the tracer formation reaction rate constants that have not yet been measured or estimated for bulk solutions.

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