Secondary Organic Aerosol Formation from Nitrate Photochemistry
EMSL Project ID
24590
Abstract
Secondary organic aerosols (SOA) in the troposphere are a major component of particulate matter and hence of interest with respect to health effects, visibility and radiative forcing. However, their mechanisms of formation are not well known, with a gap of about an order of magnitude between measured and predicted SOA. One possible contributing pathway is the oxidation of gaseous organics on contact with particles containing nitrate during the day. Nitrate ions have a rich photochemistry which generates both OH free radicals and O(3P), both of which will react with unsaturated alkenes such as the biogenic hydrocarbons. In a DOE-sponsored project, we have observed the formation of trans-sobrerol when deliquesced sodium nitrate is irradiated in the actinic region in the presence of gaseous -pinene. This low-volatility product is not formed from the gas phase oxidation by OH or O3, indicating that it is potentially a unique marker of the nitrate-pinene chemistry. In addition, we have observed the formation of SOA in this system. Working with Dr. Alla Zelenyuk in preliminary experiments at PNNL, these were shown to clearly be organic SOA. Recent studies with Dr. Liz Alexander using the PTR-MS showed that the new particle formation and growth was controlled by the amount of -pinene remaining in the gas phase. This proposal is to greatly expand these initial studies using our newly designed flow system at UCI. Deliquesced nitrate particles will be generated and EMSL user equipment, the SPLAT-MS, PTR-MS and the Aerodyne Time-of-Flight Aerosol Mass Spectrometer (TOF-AMS), applied to follow the chemical composition of both the particle and gas phases in real time. Complementing these measurements by EMSL scientists will be UCI-staff measurement of particle size distributions using SMPS (DMA and nano-DMA) and APS systems. Light scattering is measured using a three wavelength nephelometer. Gases are measured using GC-MS. NOx and O3 are measured using chemiluminescence and UV commercial analyzers respectively. Particles can be collected using a Sioutas impactor and analyzed using conventional GC-MS, MALDI-MS, HPLC-MS, ion chromatography etc. A long path FTIR cell is also available for determining particle composition as well as water uptake by the particles. Initial studies will focus on the -pinene chemistry since we have a great deal of data on this system already, but we plan to extend it to other known SOA precursors such as the aromatic as well. This combined effort will help to assess the potential contribution of the nitrate-induced photoxidation of organics to SOA formation.
Project Details
Project type
Large-Scale EMSL Research
Start Date
2007-05-31
End Date
2010-09-30
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members
Related Publications
Bruns EA, VM Perraud, J Greaves, and BJ Finlayson-Pitts. 2010. "Atmospheric Solids Analysis Probe Mass Spectrometry: A New Approach for Airborne Particle Analysis." Analytical Chemistry 82(14):5922–5927. doi:10.1021/ac101028j
Bruns E, V Perraud, A Zelenyuk, MJ Ezell, SN Johnson, Y Yu, D Imre, BJ Finlayson-Pitts, and ML Alexander. 2010. "Comparison of FTIR and Particle Mass Spectrometry for the Measurement of Paticulate Organic Nitrates." Environmental Science & Technology 44(3):1056-1061. doi:10.1021/es9029864
Ezell MJ, SN Johnson, Y Yu, V Perraud, E Bruns, ML Alexander, A Zelenyuk, D Dabdub, and BJ Finlayson-Pitts. 2010. "A New Aerosol Flow System for Photochemical and Thermal Studies of Tropospheric Aerosols." Aerosol Science and Technology 44(5):329-338. doi:10.1080/02786821003639700
Kamboures MA, JD Raff, Y Miller, LF Phillips, BJ Finlayson-Pitts, and RB Gerber. 2008. "Complexes of HNO? and NO?¯ with NO? and N?O?, and their potential role in atmospheric HONO formation." Physical Chemistry Chemical Physics. PCCP 10:6019–6032. doi:10.1039/b805330h
Perraud VM, EA Bruns, MJ Ezell, SN Johnson, J Greaves, and BJ Finlayson-Pitts. 2010. "Identification of Organic Nitrates in the NO3 Radical Initiated Oxidation of r-Pinene by Atmospheric Pressure Chemical Ionization Mass Spectrometry." Environmental Science & Technology 44(15):5887–5893. doi:10.1021/es1005658
Perraud VM, EA Bruns, MJ Ezell, SN Johnson, Y Yu, ML Alexander, A Zelenyuk, D Imre, WL Chang, D Dabdub, JF Pankow, and BJ Finlayson-Pitts. 2012. "Nonequilibrium Atmospheric Secondary Organic Aerosol Formation and Growth." Proceedings of the National Academy of Sciences of the United States of America 109(8):2836-2841. doi:10.1073/pnas.1119909109
Yu Y, MJ Ezell, A Zelenyuk, DG Imre, ML Alexander, JV Ortega, B D'Anna, CW Harmon, S Johnson, and BJ Finlayson-Pitts. 2008. "Photooxidation of Alpha-Pinene at High Relative Humidity in the Presence of Increasing Concentrations of NOx." Atmospheric Environment 42(20):5044-5060. doi:10.1016/j.atmosenv.2008.02.026
Yu Y, MJ Ezell, A Zelenyuk, DG Imre, ML Alexander, JV Ortega, JL Thomas, K Gogna, DJ Tobias, B D'Anna, CW Harmon, S Johnson, and BJ Finlayson-Pitts. 2008. "Nitrate Ion Photochemistry at Interfaces: A New Mechanism for Oxidation of alpha-Pinene." Physical Chemistry Chemical Physics. PCCP 10(21):3063-3071. doi:10.1039/b719495a
Yu Y, ML Alexander, V Perraud, E Bruns, S Johnson, M Ezell, and BJ Finlayson-Pitts. 2009. "Contamination from electrically conductive silicone tubing during aerosol chemical analysis." Atmospheric Environment 43(17):2836-2839.
Zelenyuk A, J Yang, and DG Imre. 2009. "Comparison Between Mass Spectra of Individual Organic Particles Generated by UV Laser Ablation and in the IR/UV Two-Step Mode." International Journal of Mass Spectrometry 282(1-2):6-12.
Zelenyuk A, J Yang, C Song, RA Zaveri, and DG Imre. 2008. "A New Real-Time Method for Determining Particles Sphericity and Density: Application to Secondary Organic Aerosol Formed by Ozonolysis of alpha-Pinene." Environmental Science & Technology 42(21):8033-8038. doi:10.1021/es8013562
Zelenyuk A, MJ Ezell, V Perraud, SN Johnson, E Bruns, Y Yu, D Imre, ML Alexander, and BJ Finlayson-Pitts. 2010. "Characterization of Organic Coatings on Hygroscopic Salt Particles and their Atmospheric Impacts." Atmospheric Environment 44(9):1209-1218. doi:10.1016/j.atmosenv.2009.11.047