scholarly journals <i>α</i>-Pinene secondary organic aerosol at low temperature: chemical composition and implications for particle viscosity

2018 ◽  
Vol 18 (4) ◽  
pp. 2883-2898 ◽  
Author(s):  
Wei Huang ◽  
Harald Saathoff ◽  
Aki Pajunoja ◽  
Xiaoli Shen ◽  
Karl-Heinz Naumann ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Low Temperature ◽  
Physicochemical Properties ◽  
Mass Fraction ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Formation Temperature ◽  
Mass Fractions

Abstract. Chemical composition, size distributions, and degree of oligomerization of secondary organic aerosol (SOA) from α-pinene (C10H16) ozonolysis were investigated for low-temperature conditions (223 K). Two types of experiments were performed using two simulation chambers at the Karlsruhe Institute of Technology: the Aerosol Preparation and Characterization (APC) chamber, and the Aerosol Interaction and Dynamics in the Atmosphere (AIDA) chamber. Experiment type 1 simulated SOA formation at upper tropospheric conditions: SOA was generated in the AIDA chamber directly at 223 K at 61 % relative humidity (RH; experiment termed “cold humid”, CH) and for comparison at 6 % RH (experiment termed “cold dry”, CD) conditions. Experiment type 2 simulated SOA uplifting: SOA was formed in the APC chamber at room temperature (296 K) and < 1 % RH (experiment termed “warm dry”, WD) or 21 % RH (experiment termed “warm humid”, WH) conditions, and then partially transferred to the AIDA chamber kept at 223 K, and 61 % RH (WDtoCH) or 30 % RH (WHtoCH), respectively. Precursor concentrations varied between 0.7 and 2.2 ppm α-pinene, and between 2.3 and 1.8 ppm ozone for type 1 and type 2 experiments, respectively. Among other instrumentation, a chemical ionization mass spectrometer (CIMS) coupled to a filter inlet for gases and aerosols (FIGAERO), deploying I− as reagent ion, was used for SOA chemical composition analysis. For type 1 experiments with lower α-pinene concentrations and cold SOA formation temperature (223 K), smaller particles of 100–300 nm vacuum aerodynamic diameter (dva) and higher mass fractions (> 40 %) of adducts (molecules with more than 10 carbon atoms) of α-pinene oxidation products were observed. For type 2 experiments with higher α-pinene concentrations and warm SOA formation temperature (296 K), larger particles (∼ 500 nm dva) with smaller mass fractions of adducts (< 35 %) were produced. We also observed differences (up to 20 ∘C) in maximum desorption temperature (Tmax) of individual compounds desorbing from the particles deposited on the FIGAERO Teflon filter for different experiments, indicating that Tmax is not purely a function of a compound's vapor pressure or volatility, but is also influenced by diffusion limitations within the particles (particle viscosity), interactions between particles deposited on the filter (particle matrix), and/or particle mass on the filter. Highest Tmax were observed for SOA under dry conditions and with higher adduct mass fraction; lowest Tmax were observed for SOA under humid conditions and with lower adduct mass fraction. The observations indicate that particle viscosity may be influenced by intra- and inter-molecular hydrogen bonding between oligomers, and particle water uptake, even under such low-temperature conditions. Our results suggest that particle physicochemical properties such as viscosity and oligomer content mutually influence each other, and that variation in Tmax of particle desorptions may have implications for particle viscosity and particle matrix effects. The differences in particle physicochemical properties observed between our different experiments demonstrate the importance of taking experimental conditions into consideration when interpreting data from laboratory studies or using them as input in climate models.

scholarly journals α-pinene secondary organic aerosol at low temperature: Chemical composition and implications for particle viscosity

2017 ◽  
Author(s):  
Wei Huang ◽  
Harald Saathoff ◽  
Aki Pajunoja ◽  
Xiaoli Shen ◽  
Karl-Heinz Naumann ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Low Temperature ◽  
Physicochemical Properties ◽  
Mass Fraction ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Formation Temperature ◽  
Mass Fractions

Abstract. Chemical composition and viscosity of secondary organic aerosol (SOA) from α-pinene (C10H16) ozonolysis were investigated for low temperature conditions (223 K). Two types of experiments were performed using two simulation chambers at the Karlsruhe Institute of Technology, the Aerosol Preparation and Characterization chamber (APC), and the Aerosol Interaction and Dynamics in the Atmosphere chamber (AIDA). Experiment type 1 simulated SOA formation at upper tropospheric conditions: SOA was generated in the AIDA chamber directly at 223 K, 61 % relative humidity (RH) (experiment termed cold humid, CH), or for comparison at 6 % RH (experiment termed cold dry, CD) conditions. Experiment type 2 simulated SOA uplifting: SOA was formed in the APC chamber at room temperature (296 K), <1 % RH (experiment termed warm dry, WD) or 21 % RH (experiment termed warm humid, WH) conditions, and then partially transferred to the AIDA chamber kept at 223 K, and 61 % RH (WDtoCH) or 30 % RH (WHtoCH), respectively. Precursor concentrations varied between 0.7 and 2.2 ppm α-pinene, and 2.3 and 1.8 ppm ozone for type 1 and type 2 experiments, respectively. Among other instrumentation, a chemical ionization mass spectrometer (CIMS) with filter inlet for gases and aerosols (FIGAERO), deploying I- as reagent ion, was used for SOA chemical composition analysis. For type 1 experiments with lower α-pinene concentration and cold SOA formation temperature (223 K), smaller particles of 100–300 nm vacuum aerodynamic diameter (dva) and higher mass fractions (>40 %) of adducts (molecules with more than 10 carbon atoms) of α-pinene oxidation products were observed. For type 2 experiments with higher α-pinene concentration and warm SOA formation temperature (296 K), larger particles (~500 nm dva) with smaller mass fractions of adducts (<35 %) were produced. We also observed differences (up to 20 ºC) in maximum desorption temperature (Tmax) of individual compounds desorbing from the particles deposited on the FIGAERO Teflon filter for different experiments, indicating that Tmax is not purely a function of a compound's vapor pressure or volatility, but is also influenced by diffusion limitations within the particles (particle viscosity), interactions between particles deposited on the filter (particle matrix), and/or particle mass on the filter. Highest Tmax were observed for SOA under dry conditions and with higher adduct mass fraction; lowest Tmax for SOA under humid conditions and with lowest adduct mass fraction. The observations indicate that particle viscosity may be influenced by intra- and inter-molecular hydrogen bonding between oligomers, and particle water uptake, even under such low temperature conditions. Our results suggest that particle physicochemical properties such as viscosity and oligomer content mutually influence each other, and that variation in Tmax of particle desorptions may provide implications for particle viscosity and particle matrix effects. The differences in particle physicochemical properties observed between our different experiments demonstrate the importance of taking experimental conditions into consideration when interpreting data from laboratory studies or using them as input in climate models.

scholarly journals Temperature Effects on Optical Properties and Chemical Composition of Secondary Organic Aerosol Derived from <i>n</i>-Dodecane

2020 ◽  
Author(s):  
Junling Li ◽  
Weigang Wang ◽  
Kun Li ◽  
Wenyu Zhang ◽  
Chao Peng ◽  
...  
Keyword(s):  
Optical Properties ◽  
Chemical Composition ◽  
Low Temperature ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Vital Role ◽  
Mass Spectrometry Analysis ◽  
Chemical Transformations ◽  
Spectrometry Analysis ◽  
Temperature Conditions

Abstract. Environmental temperature plays a vital role in controlling chemical transformations that lead to the formation of secondary organic aerosol (SOA), and ultimately impact composition and optical properties of the aerosol particles. In this study, we investigate optical properties of n-dodecane secondary organic aerosol under two temperature conditions: 5 °C and 25 °C. It is shown that low temperature can enhance the real part of refractive index (RI) of the SOA at the wavelengths of 532 nm and 375 nm. Mass spectrometry analysis reveals that molecular composition of n-dodecane SOA is significantly modified by temperature: a large amount of oligomers are formed under low temperature condition, which lead to higher RI values. These findings will help improve our understanding of the chemical composition and optical properties of SOA under different temperature conditions, and provide another possible explanation of the low visibility during winter.

scholarly journals Temperature effects on optical properties and chemical composition of secondary organic aerosol derived from <i>n</i>-dodecane

2020 ◽  
Vol 20 (13) ◽  
pp. 8123-8137 ◽  
Author(s):  
Junling Li ◽  
Weigang Wang ◽  
Kun Li ◽  
Wenyu Zhang ◽  
Chao Peng ◽  
...  
Keyword(s):  
Optical Properties ◽  
Chemical Composition ◽  
Low Temperature ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Vital Role ◽  
Mass Spectrometry Analysis ◽  
Chemical Transformations ◽  
Spectrometry Analysis ◽  
Temperature Conditions

Abstract. Environmental temperature plays a vital role in controlling chemical transformations that lead to the formation of secondary organic aerosol (SOA) and ultimately impact the composition and optical properties of the aerosol particles. In this study, we investigated optical properties of n-dodecane SOA under two temperature conditions: 5 and 25 ∘C. It was shown that low-temperature conditions could enhance the real part of the refractive index (RI) of the SOA at wavelengths of 532 and 375 nm. Mass spectrometry analysis revealed that the molecular composition of n-dodecane SOA was significantly modified by temperature: a large amount of oligomers were formed under low-temperature conditions, which led to higher RI values. These findings will help improve our understanding of the chemical composition and optical properties of SOA under different temperature conditions and will provide one possible explanation for the low visibility in suburban areas during winter.

scholarly journals The formation of SOA and chemical tracer compounds from the photooxidation of naphthalene and its methyl analogs in the presence and absence of nitrogen oxides

2012 ◽  
Vol 12 (18) ◽  
pp. 8711-8726 ◽  
Author(s):  
T. E. Kleindienst ◽  
M. Jaoui ◽  
M. Lewandowski ◽  
J. H. Offenberg ◽  
K. S. Docherty
Keyword(s):  
Nitrogen Oxides ◽  
Phthalic Anhydride ◽  
Mass Fraction ◽  
Phthalic Acid ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Primary Sources ◽  
Smog Chamber ◽  
Mass Fractions ◽  
Presence And Absence

Abstract. Laboratory smog chamber experiments have been carried out to investigate secondary organic aerosol (SOA) formation from the photooxidation of naphthalene and its methyl analogs, 1- and 2-methylnaphthalene (1-MN and 2-MN, respectively). Laboratory smog chamber irradiations were conducted in a flow mode to ensure adequate collection of the aerosol at reasonably low reactant concentrations and in the presence and absence of nitrogen oxides. Phthalic acid and methyl analogs were identified following BSTFA derivatization of the aerosol extract. These compounds were examined to determine whether they could serve as reasonable molecular tracers to estimate the contributions of these precursors to ambient PM2.5. Measurements were also made to determine aerosol parameters from secondary organic aerosol from naphthalene, 1-MN, and 2-MN. A mass fraction approach was used to establish factors which could be applied to phthalic acid concentrations in ambient aerosols, assuming a negligible contribution from primary sources. Phthalic anhydride uptake (and hydrolysis) was tested and found to represent a moderate filter artifact in filter measurements with and without in-line denuders. This study provided the opportunity to examine differences using authentic standards for phthalic acid compared to surrogate standards. While the mass fraction based on a surrogate compounds was somewhat lower, the differences are largely unimportant. For naphthalene, mass fractions of 0.0199 (recommended for ambient samples) and 0.0206 were determined in the presence and absence of nitrogen oxides, respectively, based on phthalic acid standards. The mass fractions determined from the laboratory data were applied to ambient samples where phthalic acid was found and expressed "as naphthalene" since phthalic acid was found to be produced in the particle phase from other methylnaphthalenes. The mass fraction values were applied to samples taken during the 2005 SOAR Study in Riverside, CA and 2010 CalNex Study in Pasadena. In both studies an undetermined isomer of methylphthalic acid was detected in addition to phthalic acid. Laboratory experiment retention times and mass spectra suggest that the major precursor for this compound is 2-MN. For the CalNex Study, SOC values for the 2-ring precursor PAHs (as naphthalene) were found to range from below the detection limit to 20 ngC m−3 which with the laboratory mass fraction data suggests an upper limit of approximately 1 μg m−3 for SOA due to 2-ring PAHs. Temporal data over the course of the one-month CalNex study suggest that primary sources of phthalic acid were probably negligible during this study period. However, the values must still be considered upper limits given a potential hydrolysis reaction or uptake of phthalic anhydride (subsequently hydrolyzed) onto the collection media.

Chemical Composition of Secondary Organic Aerosol Formed from the Photooxidation of Isoprene

2006 ◽  
Vol 110 (31) ◽  
pp. 9665-9690 ◽  
Author(s):  
Jason D. Surratt ◽  
Shane M. Murphy ◽  
Jesse H. Kroll ◽  
Nga L. Ng ◽  
Lea Hildebrandt ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol

scholarly journals Impact of molecular structure on secondary organic aerosol formation from aromatic hydrocarbon photooxidation under low NO<sub><i>x</i></sub> conditions

2016 ◽  
Author(s):  
L. Li ◽  
P. Tang ◽  
S. Nakao ◽  
D. R. Cocker III
Keyword(s):  
Molecular Structure ◽  
Chemical Composition ◽  
Aromatic Hydrocarbon ◽  
Chain Length ◽  
Aromatic Hydrocarbons ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Ortho Position ◽  
Aerosol Formation ◽  
The Impact

Abstract. The molecular structure of volatile organic compounds (VOC) determines their oxidation pathway, directly impacting secondary organic aerosol (SOA) formation. This study comprehensively investigates the impact of molecular structure on SOA formation from the photooxidation of twelve different eight to nine carbon aromatic hydrocarbons under low NOx conditions. The effects of the alkyl substitute number, location, carbon chain length and branching structure on the photooxidation of aromatic hydrocarbons are demonstrated by analyzing SOA yield, chemical composition and physical properties. Aromatic hydrocarbons, categorized into five groups, show a yield order of ortho (o-xylene and o-ethyltoluene) > one substitute (ethylbenzene, propylbenzene and isopropylbenzene) > meta (m-xylene and m-ethyltoluene) > three substitute (trimethylbenzenes) > para (p-xylene and p-ethyltoluene). SOA yields of aromatic hydrocarbon photooxidation do not monotonically decrease when increasing alkyl substitute number. The ortho position promotes SOA formation while the para position suppresses aromatic oxidation and SOA formation. Observed SOA chemical composition and volatility confirm that higher yield is associated with further oxidation. SOA chemical composition also suggests that aromatic oxidation increases with increasing alkyl substitute chain length and branching structure. Further, carbon dilution theory developed by Li et al. (2015a) is extended in this study to serve as a standard method to determine the extent of oxidation of an alkyl substituted aromatic hydrocarbon.

scholarly journals Temperature and volatile organic compound concentrations as controlling factors for chemical composition of <i>α</i>-pinene-derived secondary organic aerosol

2021 ◽  
Vol 21 (15) ◽  
pp. 11545-11562
Author(s):  
Louise N. Jensen ◽  
Manjula R. Canagaratna ◽  
Kasper Kristensen ◽  
Lauriane L. J. Quéléver ◽  
Bernadette Rosati ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Organic Compound ◽  
Organic Acids ◽  
Organic Acid ◽  
Elemental Composition ◽  
Volatile Organic Compound ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Oxidation Level ◽  
Volatile Organic

Abstract. This work investigates the individual and combined effects of temperature and volatile organic compound precursor concentrations on the chemical composition of particles formed in the dark ozonolysis of α-pinene. All experiments were conducted in a 5 m3 Teflon chamber at an initial ozone concentration of 100 ppb and initial α-pinene concentrations of 10 and 50 ppb, respectively; at constant temperatures of 20, 0, or −15 ∘C; and at changing temperatures (ramps) from −15 to 20 and from 20 to −15 ∘C. The chemical composition of the particles was probed using a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS). A four-factor solution of a positive matrix factorization (PMF) analysis of the combined HR-ToF-AMS data is presented. The PMF analysis and the elemental composition analysis of individual experiments show that secondary organic aerosol particles with the highest oxidation level are formed from the lowest initial α-pinene concentration (10 ppb) and at the highest temperature (20 ∘C). A higher initial α-pinene concentration (50 ppb) and/or lower temperature (0 or −15 ∘C) results in a lower oxidation level of the molecules contained in the particles. With respect to the carbon oxidation state, particles formed at 0 ∘C are more comparable to particles formed at −15 ∘C than to those formed at 20 ∘C. A remarkable observation is that changes in temperature during particle formation result in only minor changes in the elemental composition of the particles. Thus, the temperature at which aerosol particle formation is induced seems to be a critical parameter for the particle elemental composition. Comparison of the HR-ToF-AMS-derived estimates of the content of organic acids in the particles based on m/z 44 in the mass spectra show good agreement with results from off-line molecular analysis of particle filter samples collected from the same experiments. Higher temperatures are associated with a decrease in the absolute mass concentrations of organic acids (R-COOH) and organic acid functionalities (-COOH), while the organic acid functionalities account for an increasing fraction of the measured particle mass.

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