scholarly journals Exploring the composition and volatility of secondary organic aerosols in mixed anthropogenic and biogenic precursor systems

2021 ◽  
Vol 21 (18) ◽  
pp. 14251-14273
Author(s):  
Aristeidis Voliotis ◽  
Yu Wang ◽  
Yunqi Shao ◽  
Mao Du ◽  
Thomas J. Bannan ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Chemical Ionization ◽  
Organic Aerosol ◽  
Ionization Mass ◽  
Resolution Time ◽  
Photo Oxidation ◽  
Single Precursor ◽  
Thermal Techniques ◽  
The Individual ◽  
Volatile Precursors

Abstract. Secondary organic aerosol (SOA) formation from mixtures of volatile precursors may be influenced by the molecular interactions of the components of the mixture. Here, we report measurements of the volatility distribution of SOA formed from the photo-oxidation of o-cresol, α-pinene, and their mixtures, representative anthropogenic and biogenic precursors, in an atmospheric simulation chamber. The combination of two independent thermal techniques (thermal denuder, TD, and the Filter Inlet for Gases and Aerosols coupled to a high-resolution time-of-flight chemical ionization mass spectrometer, FIGAERO-CIMS) to measure the particle volatility, along with detailed gas- and particle-phase composition measurements, provides links between the chemical composition of the mixture and the resultant SOA particle volatility. The SOA particle volatility obtained by the two independent techniques showed substantial discrepancies. The particle volatility obtained by the TD was wider, spanning across the LVOC and SVOC range, while the respective FIGAERO-CIMS derived using two different methods (i.e. calibrated Tmax and partitioning calculations) was substantially higher (mainly in the SVOC and IVOC, respectively) and narrow. Although the quantification of the SOA particle volatility was challenging, both techniques and methods showed similar trends, with the volatility of the SOA formed from the photo-oxidation of α-pinene being higher than that measured in the o-cresol system, while the volatility of the SOA particles of the mixture was between those measured at the single-precursor systems. This behaviour could be explained by two opposite effects, the scavenging of the larger molecules with lower volatility produced in the single-precursor experiments that led to an increase in the average volatility and the formation of unique-to-the-mixture products that had higher O:C, MW, OSc‾ and, consequently, lower volatility compared to those derived from the individual precursors. We further discuss the potential limitations of FIGAERO-CIMS to report quantitative volatilities and their implications for the reported results, and we show that the particle volatility changes can be qualitatively assessed, while caution should be taken when linking the chemical composition to the particle volatility. These results present the first detailed observations of SOA particle volatility and composition in mixed anthropogenic and biogenic systems and provide an analytical context that can be used to explore particle volatility in chamber experiments.

scholarly journals Exploring the composition and volatility of secondary organic aerosols in mixed anthropogenic and biogenic precursor systems

2021 ◽  
Author(s):  
Aristeidis Voliotis ◽  
Yu Wang ◽  
Yunqi Shao ◽  
Mao Du ◽  
Thomas J. Bannan ◽  
...  
Keyword(s):  
Chemical Composition ◽  
New Product ◽  
Organic Aerosol ◽  
Product Formation ◽  
Particle Phase ◽  
Resolution Time ◽  
Effective Saturation ◽  
Thermal Techniques ◽  
The Individual ◽  
Volatile Precursors

Abstract. Secondary organic aerosol (SOA) formation from mixtures of volatile precursors may be influenced by the molecular interactions of the products of the components of the mixture. Here, we report measurements of the volatility distribution of SOA formed from the photo-oxidation o-cresol, α-pinene and their mixtures, representative anthropogenic and biogenic precursors, in an atmospheric simulation chamber. The combination of two independent thermal techniques (thermal denuder and the Filter Inlet for Gases and Aerosols coupled to a high resolution time of flight chemical ionisation mass spectrometer) to measure the particle volatility, along with detailed gas and particle phase composition measurements provides links between the chemical composition of the mixture and the resultant SOA volatility. The products that were only present in the SOA of the mixture had higher O:C and lower volatility compared to those deriving from the individual precursors. This suggests that new product formation can reduce the volatility in mixtures. At the same time, some of the larger molecules with lower volatility produced in the single α-pinene and o-cresol system were not present in the mixture leading to an increase of the average volatility. These opposite effects resulted the volatility distribution of the SOA of the mixture to be between those of the individual precursors. For example, compounds with effective saturation concentration less or equal than 0.01 μg m−3 represented 28, 39 and 37 % of the SOA mass in the α-pinene, o-cresol and mixed precursor experiments, respectively. We further explore the sensitivity limitations of our technique to the reported results and we show that the particle volatility can be qualitatively assessed, while caution should be held when linking the chemical composition to the particle volatility. These results provide the first detailed observations of SOA particle volatility and composition in mixed anthropogenic and biogenic systems and provides an analytical context that can be used to explore particle volatility in chamber experiments.

scholarly journals Seasonal characteristics of organic aerosol chemical composition and volatility in Stuttgart, Germany

2019 ◽  
Vol 19 (18) ◽  
pp. 11687-11700 ◽  
Author(s):  
Wei Huang ◽  
Harald Saathoff ◽  
Xiaoli Shen ◽  
Ramakrishna Ramisetty ◽  
Thomas Leisner ◽  
...  
Keyword(s):  
Chemical Composition ◽  
High Resolution ◽  
Organic Compounds ◽  
Mass Spectrometer ◽  
Time Of Flight ◽  
Organic Aerosol ◽  
Molecular Composition ◽  
Winter Period ◽  
Ionization Mass ◽  
Resolution Time

Abstract. The chemical composition and volatility of organic aerosol (OA) particles were investigated during July–August 2017 and February–March 2018 in the city of Stuttgart, one of the most polluted cities in Germany. Total non-refractory particle mass was measured with a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS; hereafter AMS). Aerosol particles were collected on filters and analyzed in the laboratory with a filter inlet for gases and aerosols coupled to a high-resolution time-of-flight chemical ionization mass spectrometer (FIGAERO-HR-ToF-CIMS; hereafter CIMS), yielding the molecular composition of oxygenated OA (OOA) compounds. While the average organic mass loadings are lower in the summer period (5.1±3.2 µg m−3) than in the winter period (8.4±5.6 µg m−3), we find relatively larger mass contributions of organics measured by AMS in summer (68.8±13.4 %) compared to winter (34.8±9.5 %). CIMS mass spectra show OOA compounds in summer have O : C of 0.82±0.02 and are more influenced by biogenic emissions, while OOA compounds in winter have O : C of 0.89±0.06 and are more influenced by biomass burning emissions. Volatility parametrization analysis shows that OOA in winter is less volatile with higher contributions of low-volatility organic compounds (LVOCs) and extremely low-volatility organic compounds (ELVOCs). We partially explain this by the higher contributions of compounds with shorter carbon chain lengths and a higher number of oxygen atoms, i.e., higher O : C in winter. Organic compounds desorbing from the particles deposited on the filter samples also exhibit a shift of signal to higher desorption temperatures (i.e., lower apparent volatility) in winter. This is consistent with the relatively higher O : C in winter but may also be related to higher particle viscosity due to the higher contributions of larger-molecular-weight LVOCs and ELVOCs, interactions between different species and/or particles (particle matrix), and/or thermal decomposition of larger molecules. The results suggest that whereas lower temperature in winter may lead to increased partitioning of semi-volatile organic compounds (SVOCs) into the particle phase, this does not result in a higher overall volatility of OOA in winter and that the difference in sources and/or chemistry between the seasons plays a more important role. Our study provides insights into the seasonal variation of the molecular composition and volatility of ambient OA particles and into their potential sources.

scholarly journals Chemical characterization of secondary organic aerosol at a rural site in the southeastern US: insights from simultaneous high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) and FIGAERO chemical ionization mass spectrometer (CIMS) measurements

2020 ◽  
Vol 20 (14) ◽  
pp. 8421-8440
Author(s):  
Yunle Chen ◽  
Masayuki Takeuchi ◽  
Theodora Nah ◽  
Lu Xu ◽  
Manjula R. Canagaratna ◽  
...  
Keyword(s):  
High Resolution ◽  
Mass Spectrometer ◽  
Chemical Ionization ◽  
Secondary Organic Aerosol ◽  
Time Of Flight ◽  
Organic Aerosol ◽  
Ionization Mass ◽  
Resolution Time ◽  
Aerosol Mass Spectrometer ◽  
Aerosol Mass

Abstract. The formation and evolution of secondary organic aerosol (SOA) were investigated at Yorkville, GA, in late summer (mid-August to mid-October 2016). The organic aerosol (OA) composition was measured using two online mass spectrometry instruments, the high-resolution time-of-flight aerosol mass spectrometer (AMS) and the Filter Inlet for Gases and AEROsols coupled to a high-resolution time-of-flight iodide-adduct chemical ionization mass spectrometer (FIGAERO-CIMS). Through analysis of speciated organics data from FIGAERO-CIMS and factorization analysis of data obtained from both instruments, we observed notable SOA formation from isoprene and monoterpenes during both day and night. Specifically, in addition to isoprene epoxydiol (IEPOX) uptake, we identified isoprene SOA formation from non-IEPOX pathways and isoprene organic nitrate formation via photooxidation in the presence of NOx and nitrate radical oxidation. Monoterpenes were found to be the most important SOA precursors at night. We observed significant contributions from highly oxidized acid-like compounds to the aged OA factor from FIGAERO-CIMS. Taken together, our results showed that FIGAERO-CIMS measurements are highly complementary to the extensively used AMS factorization analysis, and together they provide more comprehensive insights into OA sources and composition.

scholarly journals Hygroscopicity and composition of Alaskan Arctic CCN during April 2008

2011 ◽  
Vol 11 (8) ◽  
pp. 21789-21834
Author(s):  
R. H. Moore ◽  
R. Bahreini ◽  
C. A. Brock ◽  
K. D. Froyd ◽  
J. Cozic ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Cloud Condensation Nuclei ◽  
Anthropogenic Pollution ◽  
Organic Aerosol ◽  
International Polar Year ◽  
Mass Spectral ◽  
Aerosol Mass ◽  
Alaskan Arctic ◽  
Air Mass Types ◽  
The Individual

Abstract. We present a comprehensive characterization of cloud condensation nuclei (CCN) sampled in the Alaskan Arctic during the 2008 Aerosol, Radiation, and Cloud Processes affecting Arctic Climate (ARCPAC) project, a component of the POLARCAT and International Polar Year (IPY) initiatives. Four distinct air mass types were sampled including relatively pristine Arctic background conditions as well as biomass burning and anthropogenic pollution plumes. Despite differences in chemical composition, inferred aerosol hygroscopicities were fairly invariant and ranged from κ = 0.1–0.3 over the atmospherically-relevant range of water vapor supersaturations studied. Analysis of the individual mass spectral m/z 43 and 44 peaks from an aerosol mass spectrometer show the organic aerosols sampled to be well-oxygenated, consistent with with long-range transport and aerosol aging processes. However, inferred hygroscopicities are less than would be predicted based on previous parameterizations of biogenic oxygenated organic aerosol, suggesting an upper limit on organic aerosol hygroscopicity above which κ is less sensitive to the O:C ratio. Most Arctic aerosol act as CCN above 0.1 % supersaturation, although the data suggest the presence of an externally-mixed, non-CCN-active mode comprising approximately 0–20 % of the aerosol number. CCN closure was assessed using measured size distributions, bulk chemical composition measurements, and assumed aerosol mixing states; CCN predictions tended toward overprediction, with the best agreement (± 0–20 %) obtained by assuming the aerosol to be externally-mixed with soluble organics. Closure also varied with CCN concentration, and the best agreement was found for CCN concentrations above 100 cm−3 with a 1.5- to 3-fold overprediction at lower concentrations.

scholarly journals Chemical Characterization of Secondary Organic Aerosol at a Rural Site in the Southeastern U.S.: Insights from Simultaneous HR-ToF-AMS and FIGAERO-CIMS Measurements

2020 ◽  
Author(s):  
Yunle Chen ◽  
Masayuki Takeuchi ◽  
Theodora Nah ◽  
Lu Xu ◽  
Manjula R. Canagaratna ◽  
...  
Keyword(s):  
High Resolution ◽  
Mass Spectrometer ◽  
Secondary Organic Aerosol ◽  
Time Of Flight ◽  
Organic Aerosol ◽  
Rural Site ◽  
Organic Nitrate ◽  
Ionization Mass ◽  
Resolution Time ◽  
Radical Oxidation

Abstract. The formation and evolution of secondary organic aerosol (SOA) was investigated at Yorkville, GA, in late summer (mid-August ~ mid-October, 2016). Organic aerosol (OA) composition was measured using two on-line mass spectrometry instruments, the high-resolution time-of-flight aerosol mass spectrometer (AMS) and the Filter Inlet for Gases and AEROsols coupled to a high-resolution time-of-flight iodide-adduct chemical ionization mass spectrometer (FIGAERO-CIMS). Through analysis of speciated organics data from FIGAERO-CIMS and factorization analysis of data obtained from both instruments, we observed notable SOA formation from isoprene and monoterpenes during both day and night. Specifically, in addition to isoprene epoxydiols (IEPOX) uptake, we identified isoprene SOA formation via hydroxyl hydroperoxide oxidation (ISOPOOH oxidation via non-IEPOX pathways) and isoprene organic nitrate formation via photooxidation in the presence of NOx and nitrate radical oxidation. Monoterpenes were found to be the most important SOA precursors at night. We observed significant contributions from highly-oxidized acid-like compounds to the aged OA factor from FIGAERO-CIMS. Taken together, our results showed that FIGAERO-CIMS measurements are highly complementary to the extensively used AMS factorization analysis, and together they provide more comprehensive insights into OA sources and composition.

Quantitation of Polychlorinated Biphenyl Residues by Electron Capture Gas-Liquid Chromatography: Reference Material Characterization and Preliminary Study

1978 ◽  
Vol 61 (2) ◽  
pp. 272-281
Author(s):  
Leon D Sawyer
Keyword(s):  
Electron Capture ◽  
Material Characterization ◽  
Chemical Ionization ◽  
Polychlorinated Biphenyl ◽  
Collaborative Study ◽  
Gas Liquid Chromatography ◽  
Ionization Mass ◽  
Preliminary Study ◽  
The Individual ◽  
Liquid Chromatographic

Abstract Weight per cent compositions of individual peaks of Aroclors 1016, 1242, 1248, 1254, and 1260 were determined under standard gas-liquid chromatographic (GLC) conditions. The GLC peak compositions were determined by using a Hall electrolytic conductivity detector for chlorine measurement and chemical ionization mass spectrometry with single ion monitoring for molecular weight characterization. The Aroclors used are available as reference materials for individual peak quantitation of polychlorinated biphenyl (PCB) residues by electron capture GLC. On the basis of a limited interlaboratory study and a collaborative study, the individual peak method shows improved interlaboratory precision and/or accuracy in PCB quantitation over existing methods.

scholarly journals Formation of Highly Oxygenated Low-Volatility Products from Cresol Oxidation

2016 ◽  
Author(s):  
Rebecca H. Schwantes ◽  
Katherine A. Schilling ◽  
Renee C. McVay ◽  
Hanna Lignell ◽  
Matthew M. Coggon ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Gas Phase ◽  
Ring Opening ◽  
Chemical Ionization ◽  
First Generation ◽  
Direct Analysis ◽  
Organic Aerosol ◽  
Oxidation Products ◽  
Ionization Mass ◽  
Particle Phase

Abstract. Hydroxyl radical (OH) oxidation of toluene produces the ring-retaining products cresol and benzaldehyde, and the ring-opening products bicyclic intermediate compounds and epoxides. Here, first- and later-generation OH oxidation products from cresol and benzaldehyde are identified in laboratory chamber experiments. For benzaldehyde, first-generation ring-retaining products are identified, but later-generation products are not detected. For cresol, low-volatility (saturation mass concentration, C* ~ 3.5 × 104–7.7 × 10−3 μg m−3) first- and later-generation ring-retaining products are identified. Subsequent OH addition to the aromatic ring of o-cresol leads to compounds such as hydroxy, dihydroxy, and trihydroxy methyl benzoquinones and dihydroxy, trihydroxy, tetrahydroxy, and pentahydroxy toluenes. These products are detected in the gas phase by chemical ionization mass spectrometry (CIMS) and in the particle phase using offline direct analysis in real time mass spectrometry (DART-MS). Our data suggest that the yield of trihydroxy toluene from dihydroxy toluene is substantial. While an exact yield cannot be reported as authentic standards are unavailable, we find that a yield for trihydroxy toluene from dihydroxy toluene of ~ 0.7 (equal to the yield of dihydroxy toluene from o-cresol) is consistent with experimental results for o-cresol oxidation under low-NO conditions. These results suggest that even though the cresol pathway accounts for only ~ 20 % of the oxidation products of toluene, it is the source of a significant fraction (~ 20–40 %) of toluene secondary organic aerosol (SOA) due to the formation of low-volatility products.

Chemical composition of summertime High Arctic aerosols using chemical ionization mass spectrometry

2020 ◽  
Author(s):  
Karolina Siegel ◽  
Paul Zieger ◽  
Matthew Salter ◽  
Ilona Riipinen ◽  
Annica M.L. Ekman ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Chemical Ionization ◽  
High Arctic ◽  
Cloud Formation ◽  
The Arctic ◽  
Formation Mechanisms ◽  
Ionization Mass ◽  
Potential Contribution ◽  
Pack Ice ◽  
Aerosol Chemical Composition

<p>Low-level clouds and fogs play a key role in the radiative balance over the Arctic pack ice by regulating surface energy fluxes. The radiative features of clouds are dependent on the amount of airborne aerosol particles and their properties, since the particles can act as CCN (cloud condensation nuclei) and INP (ice nucleating particles). As the Arctic climate is currently warming, the local emissions and formation mechanisms of aerosols are expected to change, possibly leading to altered cloud properties.</p><p>We measured aerosol chemical composition using FIGAERO-CIMS (Chemical Ionization Mass Spectrometer coupled to a Filter Inlet for Gases and AEROsols) analysis of samples collected during the MOCCHA campaign (Microbiology-Ocean-Cloud-Coupling in the High Arctic) close to the North Pole in 2018. The goal of the campaign was to investigate natural aerosol emissions from the ocean to the atmosphere during summertime in terms of local sources and potential contribution to cloud formation. The sampling period was therefore around the seasonal sea ice minimum in September. With our CIMS setup, the sample molecules are ionised by iodide ions (I<sup>-</sup>). The negatively charged adducts are then separated by mass, allowing for characterisation on a molecular level. This is the first time aerosol chemical composition of High Arctic aerosols has been measured using this technique. As the current knowledge about the atmospheric composition in this region is low, our results suggest a potential for using this method for further aerosol chemical characterisation in the pristine Arctic environment.</p><p>Our analysis shows that sulphur-containing compounds were most abundant in the aerosol samples, including sulphuric acid, sulphur trioxide, methanesulphonic acid (MSA) and dimethyl sulphoxide (DMSO). MSA and DMSO are oxidation products of dimethyl sulphide (DMS), which is released by marine phytoplankton to the atmosphere under ice-free conditions. Non-sea-salt sulphate (nss-SO<sub>4</sub><sup>2-</sup>) aerosols are known to be efficient CCN. The results will be compared to aerosol samples from the NASCENT campaign (Ny-Ålesund Aerosol and Cloud Experiment), analysed using the same CIMS technique. The campaign runs for a year during 2019-2020 at the Zeppelin station in Svalbard. Our findings are expected to contribute to better understanding of the connection between aerosols and cloud formation in the polar regions and the effects on the ocean and pack ice.</p>

scholarly journals Temperature and VOC concentration as controlling factors for chemical composition of alpha-pinene derived secondary organic aerosol

2020 ◽  
Author(s):  
Louise N. Jensen ◽  
Manjula R. Canagaratna ◽  
Kasper Kristensen ◽  
Lauriane L. J. Quéléver ◽  
Bernadette Rosati ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Organic Acids ◽  
Organic Acid ◽  
Elemental Composition ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Particle Formation ◽  
Composition Analysis ◽  
Oxidation Level ◽  
The Individual

Abstract. This work investigates the individual and combined effects of temperature and volatile organic compound precursor concentration 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 α-pinene concentrations of 10 ppb and 50 ppb, respectively, at constant temperatures of 20 °C, 0 °C, or −15 °C, and at changing temperatures (ramps) from −15 °C to 20 °C and from 20 °C 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 combined HR-ToF-AMS data from experiments conducted under different conditions is presented. The PMF analysis as well as 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). Higher initial α-pinene concentration (50 ppb) and/or lower temperature (0 °C or −15 °C) result in lower oxidation level of the molecules contained in the particles. With respect to 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 or after particle formation result in only minor changes in the elemental composition of the particles. The temperature at which aerosol particle formation is initiated thus seems to be a critical parameter for the particle elemental composition. Comparison of the AMS derived estimates of the content of organic acids in the particles based on m/z 44 in the spectra show good agreement with results from off-line molecular analysis of particle filter samples collected from the same experiments. While higher temperatures are associated with a decrease in the absolute mass concentrations of organic acids (R-COOH) and organic acid functionalities (-COOH), the organic acid functionalities account for an increasing fraction of the measured SOA mass at higher temperatures.

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