Mapping the Role of Semivolatile Organics in Aerosol Growth Dynamics
EMSL Project ID
49409
Abstract
Recent theoretical and laboratory studies have revealed that the timescales of secondary organic aerosol (SOA) partitioning and the associated aerosol growth kinetics depend on the complex interplay between SOA volatility, particle phase state/viscosity, and particle-phase reactivity. A proper representation of these physicochemical parameters in the next generation SOA models is therefore needed to reliably predict not only the total SOA mass, but also the composition and number size distributions, all of which together determine the aerosol's climate-relevant properties such as cloud nucleation and radiative balance. The objectives of this project are to: a) Investigate the fundamental role of semivolatile organics formed from oxidation of selected volatile organic compounds (in an environmental chamber) in growing aerosol particles to climate-relevant sizes by observing the evolution of particle size distributions and size-dependent phase/viscosity, morphology, volatility, and molecular composition with EMSL's single particle mass spectrometer (SPLAT II), microscopy, and ultra-high resolution orbitrap mass spectrometry techniques; b) Use the resulting data sets to develop a fundamental molecular-level understanding of SOA formation processes, aerosol growth kinetics, and a compact physicochemical parameterization for use in climate models. At the end of this project, we expect to have improved the representation of particle growth in atmospheric models by studying the fundamental relationship between SOA chemical composition, phase/viscosity, and particle growth kinetics and mechanisms. SPLAT II is uniquely suited for the proposed study because of its multidimensional approach to single particle characterization, high sensitivity to small particles, high temporal resolution, and a sub-nanometer sizing precision. SPLAT II measures in real time particle size, mass, composition, morphology, density, viscosity, shape, and evaporation kinetics. Very recently SPLAT II was equipped with pulsed VUV lamp with an exceptional brilliance and high resolution bipolar mass spectrometer that will be used for IR-laser layer-by-layer evaporation followed by soft VUV ionization to yield quantitative information on morphology and composition of individual particles. To further the online measurements by SPLAT II, we will collect aerosol samples for detailed offline analysis of particle composition and morphology with electron microscopy, micro-spectroscopy, ultra-high resolution orbitrap mass spectrometry, and nuclear magnetic resonance spectroscopy techniques available at EMSL that can provide detailed information on the molecular components present in organic aerosol material.
The detailed data sets will be used to constrain and evaluate a newly developed SOA modeling framework that takes into account the effects of volatility, phase/viscosity, and particle phase reactions on SOA formation mechanisms and growth dynamics. The proposed work addresses EMSL's Atmospheric Aerosol Systems (AAS) Science theme goal of: "characterizing fundamental properties and formation of organic aerosols to determine their climate impact, ... grow to climate-relevant sizes..."
Our work is funded by BER DOE's Atmospheric System Research (ASR) Program and is directly relevant to the three research themes of the "SOA Formation Focus Group": 1) Particle Viscosity/Phase, 2) SOA Growth Mechanisms, and 3) Sulfate as Trigger for SOA (part of ASR Working Group on Aerosol Life Cycle).
Project Details
Project type
Large-Scale EMSL Research
Start Date
2016-10-01
End Date
2019-09-30
Status
Closed
Released Data Link
Team
Principal Investigator
Co-Investigator(s)
Team Members
Related Publications
Gyawali MS, WP Arnott, RA Zaveri, C Song, B Flowers, MK Dubey, A Setyan, Q Zhang, S China, C Mazzoleni, K Gorkowski, R Subramanian, and H Moosmuller. 2017. "Evolution of Multispectral Aerosol Absorption Properties in a Biogenically?Influenced Urban Environment during the CARES Campaign." Atmosphere 8(11):217. doi:10.3390/atmos8110217
Sharma N., S. China, J. Bhandari, K. Gorkowski, M.K. Dubey, R.A. Zaveri, and C. Mazzoleni. 2018. "Physical properties of aerosol internally mixed with soot particles in a biogenically-dominated environment in California." Geophysical Research Letters 45, no. 20:11,473-11,482. PNNL-SA-136202. doi:10.1029/2018GL079404
Wang J., J.E. Shilling, J. Liu, A. Zelenyuk-Imre, D.M. Bell, M.D. Petters, and R.M. Thalman, et al. 2019. "Cloud droplet activation of secondary organic aerosol is mainly controlled by molecular weight, not by solubility." Atmospheric Chemistry and Physics 19, no. 2:941-954. PNNL-SA-140927. doi:10.5194/acp-19-941-2019