Interrogating the Formation Mechanisms of Secondary Organic Aerosols (SOA) from Aqueous-phase Reactions of Phenolic Compounds
EMSL Project ID
48009
Abstract
Secondary organic aerosol (SOA) is usually a major component of airborne particulate matter (PM). Since PM has large impacts on climate, human health, and visibility, understanding the formation and transformation mechanisms of SOA in the atmosphere is important. This proposed research aims at investigating the chemical mechanisms responsible for the photochemical formation and aging of low volatility species (i.e., SOA) formed from volatile phenolic compounds in atmospheric aqueous phases (e.g., cloud and fog drops and water-containing particles). Phenols are emitted in significant concentrations from biomass burning. They are water soluble and reactive in aqueous phase, forming low volatility products that remain as SOA in the particle phase after droplet evaporation. Recent studies by our group indicate that the aqueous oxidation of volatile phenols can be an important source of SOA. Quantifying this contribution to the atmospheric burden of SOA requires a fundamental understanding of the mechanisms of the aqueous reactions of phenols. This knowledge can be acquired by analyzing the chemical species produced from these reactions. In this project, we propose to conduct thorough analyses of the low volatility SOA species formed as a function of time in the photochemical transformation of phenolic compounds in aqueous solutions. Given the very high complexities of the aqueous reactions of phenols, we propose to take an integrated bottom-up (molecular-level characterization) and top-down (bulk characterization) approach. Specifically, we will partner with EMSL colleagues to use a High-Resolution (~ 100,000 m/delta-m) 'ESI-LTQ-Orbitrap-MS for environmental research' instrument at EMSL for characterizing the molecular composition of phenol-derived, high-molecular-weight organic species from our experiments. At UC Davis we will use High-Resolution (~ 6,000 m/delta-m) Time-of-Flight Aerosol Mass Spectrometry (HR-ToF-AMS) and Fourier transform infrared spectroscopy (FTIR) to determine the bulk chemical composition, such as the average elemental ratios and the functional group distributions of the SOA. We will also use Ion Chromatography (IC) to analyze small organic ionic species and a total organic carbon (TOC) analyzer to quantify the total carbon contents of the SOA. Finally, we will integrate the comprehensive molecular information of the aqueous reaction products of volatile phenolic species with the bulk chemical characterization results to interrogate the reaction mechanisms of phenols in atmospheric aqueous phases.
Project Details
Project type
Large-Scale EMSL Research
Start Date
2013-10-01
End Date
2015-09-30
Status
Closed
Released Data Link
Team
Principal Investigator
Co-Investigator(s)
Team Members
Related Publications
Yu L, J Smith, A Laskin, CN Anastasio, J Laskin, and Q Zhang. 2014. "Chemical characterization of SOA formed from aqueous-phase reactions of phenols with the triplet excited state of carbonyl and hydroxyl radical." Atmospheric Chemistry and Physics 14(24):13801-13816. doi:10.5194/acp-14-13801-2014