Effects of Molecular-Level Compositional Variability in Organic Aerosol on Phase State and Thermodynamic Mixing Behavior

2019 ◽  
Vol 53 (22) ◽  
pp. 13009-13018 ◽  
Author(s):  
Jenna C. Ditto ◽  
Taekyu Joo ◽  
Peeyush Khare ◽  
Roger Sheu ◽  
Masayuki Takeuchi ◽  
...  
Keyword(s):  
Phase State ◽  
Molecular Level ◽  
Organic Aerosol ◽  
Mixing Behavior ◽  
Compositional Variability

Rising Importance of Organosulfur Species for Aerosol Properties and Future Air Quality

2019 ◽  
Author(s):  
Matthieu Riva ◽  
Yuzhi Chen ◽  
Zhang, Yue ◽  
Ziying Lei ◽  
Nicole Olson ◽  
...  
Keyword(s):  
Air Quality ◽  
Physicochemical Properties ◽  
Phase State ◽  
Global Climate ◽  
Field Measurements ◽  
Organic Aerosol ◽  
Organic Sulfate ◽  
Isoprene Oxidation ◽  
Aerosol Properties ◽  
Inorganic Sulfate

<div>Acid-driven multiphase chemistry of isoprene epoxydiols (IEPOX), a key isoprene oxidation product, with inorganic sulfate aerosol yields substantial amounts of secondary organic aerosol (SOA) through the formation of organosulfur. The extent and implications of inorganic-to-organic sulfate conversion, however, are unknown. Herein, we reveal that extensive consumption of inorganic sulfate occurs, which increases with the IEPOX-to-inorganic sulfate ratio (IEPOX:Sulf<sub>inorg</sub>), as determined by laboratory and field measurements. We further demonstrate that organosulfur greatly modifies critical aerosol properties, such as acidity, morphology, viscosity, and phase state. These new mechanistic insights reveal that changes in SO<sub>2</sub> emissions, especially in isoprene-dominated environments, will significantly alter biogenic SOA physicochemical properties. Consequently, IEPOX:Sulf<sub>inorg</sub> will play a central role in understanding historical climate and determining future impacts of biogenic SOA on global climate and air quality.</div>

scholarly journals Cloud droplet activation through oxidation of organic aerosol influenced by temperature and particle phase state

2017 ◽  
Vol 44 (3) ◽  
pp. 1583-1591 ◽  
Author(s):  
Jonathan H. Slade ◽  
Manabu Shiraiwa ◽  
Andrea Arangio ◽  
Hang Su ◽  
Ulrich Pöschl ◽  
...  
Keyword(s):  
Phase State ◽  
Cloud Droplet ◽  
Organic Aerosol ◽  
Particle Phase ◽  
Droplet Activation

scholarly journals A robust clustering algorithm for analysis of composition‐dependent organic aerosol thermal desorption measurements

2019 ◽  
Author(s):  
Ziyue Li ◽  
Emma L. D'Ambro ◽  
Siegfried Schobesberger ◽  
Cassandra J. Gaston ◽  
Felipe D. Lopez-Hilfiker ◽  
...  
Keyword(s):  
Thermal Properties ◽  
Spectral Data ◽  
Thermal Desorption ◽  
Clustering Algorithm ◽  
Organic Aerosol ◽  
Relative Mass ◽  
Molecular Formula ◽  
Mass Spectral Data ◽  
Mass Spectral ◽  
Compositional Variability

Abstract. One of the challenges of understanding atmospheric organic aerosol (OA) stems from its complex composition. Mass spectrometry is commonly used to characterize the compositional variability of OA. Clustering of a mass spectral data set helps identify components that exhibit similar behavior or have similar properties, facilitating understanding of sources and processes that govern compositional variability. Here, we developed a novel clustering algorithm, Noise-Sorted Scanning Clustering (NSSC), and apply it to thermal desorption measurements from the Filter Inlet for Gases and AEROsols coupled to a chemical ionization mass spectrometer (FIGAERO CIMS). NSSC provides a robust, reproducible analysis of the FIGAERO temperature-dependent mass spectral data. The NSSC allows for determination of thermal profiles for compositionally distinct clusters, increasing the accessibility and enhancing the interpretation of FIGAERO data. Applications of NSSC to several laboratory biogenic secondary organic aerosol (BSOA) systems demonstrate the ability of NSSC to distinguish different types of thermal behaviors for the components comprising the particles along with the relative mass contributions and chemical properties (e.g. average molecular formula) of each cluster. For each of the systems examined, more than 80 % of the total mass is clustered into 9–13 clusters. Comparison of the average thermograms of the clusters between systems indicate some commonalty in terms of the thermal properties of different BSOA, although with some system-specific behavior. Application of NSSC to sets of experiments in which one experimental parameter, such as the concentration of NO, is varied demonstrates the potential for clustering to elucidate the chemical factors that drive changes in the thermal properties of OA. Further quantitative interpretation of the clustered thermograms followed by clustering will allow for more comprehensive understanding of the thermochemical properties of OA.

scholarly journals Viscosity and liquid–liquid phase separation in healthy and stressed plant SOA

2021 ◽  
Author(s):  
Natalie R. Smith ◽  
Giuseppe V. Crescenzo ◽  
Yuanzhou Huang ◽  
Anusha P. S. Hettiyadura ◽  
Kyla Siemens ◽  
...  
Keyword(s):  
Phase Separation ◽  
Liquid Phase ◽  
Volatile Organic Compounds ◽  
Organic Compounds ◽  
Phase State ◽  
Organic Aerosol ◽  
Volatile Organic ◽  
Pine Trees ◽  
Stressed Plant ◽  
Liquid Liquid Phase Separation

Molecular composition, viscosity, and phase state were investigated for secondary organic aerosol derived from synthetic mixtures of volatile organic compounds representing emissions from healthy and aphid-stressed Scots pine trees.

scholarly journals The effects of morphology, mobility size, and secondary organic aerosol (SOA) material coating on the ice nucleation activity of black carbon in the cirrus regime

2020 ◽  
Vol 20 (22) ◽  
pp. 13957-13984
Author(s):  
Cuiqi Zhang ◽  
Yue Zhang ◽  
Martin J. Wolf ◽  
Leonid Nichman ◽  
Chuanyang Shen ◽  
...  
Keyword(s):  
Black Carbon ◽  
State Transition ◽  
Phase State ◽  
Secondary Organic Aerosol ◽  
Global Climate ◽  
Surface Oxidation ◽  
Organic Aerosol ◽  
Ice Nucleation ◽  
Supersaturation Ratio ◽  
Homogeneous Freezing

Abstract. There is evidence that black carbon (BC) particles may affect cirrus formation and, hence, global climate by acting as potential ice nucleating particles (INPs) in the troposphere. Nevertheless, the ice nucleation (IN) ability of bare BC and BC coated with secondary organic aerosol (SOA) material remains uncertain. We have systematically examined the IN ability of 100–400 nm size-selected BC particles with different morphologies and different SOA coatings representative of anthropogenic (toluene and n-dodecane) and biogenic (β-caryophyllene) sources in the cirrus regime (−46 to −38 ∘C). Several BC proxies were selected to represent different particle morphologies and oxidation levels. Atmospheric aging was further replicated with the exposure of SOA-coated BC to OH. The results demonstrate that the 400 nm hydrophobic BC types nucleate ice only at or near the homogeneous freezing threshold. Ice formation at cirrus temperatures below homogeneous freezing thresholds, as opposed to purely homogeneous freezing, was observed to occur for some BC types between 100 and 200 nm within the investigated temperature range. More fractal BC particles did not consistently act as superior INPs over more spherical ones. SOA coating generated by oxidizing β-caryophyllene with O3 did not seem to affect BC IN ability, probably due to an SOA-phase state transition. However, SOA coatings generated from OH oxidation of various organic species did exhibit higher IN-onset supersaturation ratio with respect to ice (SSi), compared with bare BC particles, with the toluene-SOA coating showing an increase in SSi of 0.1–0.15 while still below the homogeneous freezing threshold. Slightly oxidized toluene SOA coating seemed to have a stronger deactivation effect on BC IN ability than highly oxidized toluene SOA, which might be caused by oligomer formation and the phase state transition of toluene SOA under different oxidation levels. n-dodecane and β-caryophyllene-derived SOA-coated BC only froze in the homogeneous regime. We attribute the inhibition of IN ability to the filling of the pores on the BC surface by the SOA material coating. OH exposure levels of n-dodecane and β-caryophyllene SOA coating experiments, from an equivalent atmospheric exposure time from 10 to 90 d, did not render significant differences in the IN potential. Our study of selected BC types and sizes suggests that increases in diameter, compactness, and/or surface oxidation of BC particles lead to more efficient IN via the pore condensation freezing (PCF) pathway, and that coatings of common SOA materials can inhibit the formation of ice.

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