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Particulate organic acids and overall water-soluble aerosol composition measurements from the 2006 Gulf of Mexico Atmospheric Composition and Climate Study (GoMACCS)

Sorooshian, Armin and Ng, Nga L. and Chan, Arthur W. H. and Feingold, Graham and Flagan, Richard C. and Seinfeld, John H. (2007) Particulate organic acids and overall water-soluble aerosol composition measurements from the 2006 Gulf of Mexico Atmospheric Composition and Climate Study (GoMACCS). Journal of Geophysical Research. Atmospheres, 112 (D3). Art. No. D13201. ISSN 2169-897X. doi:10.1029/2007JD008537. https://resolver.caltech.edu/CaltechAUTHORS:20141028-151856371

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Abstract

The Center for Interdisciplinary Remotely-Piloted Aircraft Studies (CIRPAS) Twin Otter participated in the Gulf of Mexico Atmospheric Composition and Climate Study (GoMACCS) mission during August–September 2006. A particle-into-liquid sampler (PILS) coupled to ion chromatography was used to characterize the water-soluble ion composition of aerosol and cloud droplet residual particles (976 5-min PM_(1.0) samples in total). Sulfate and ammonium dominated the water-soluble mass (NH_4+ + SO_4^(2−) = 84 ± 14%), while organic acids contributed 3.4 ± 3.7%. The average NH_4^+:SO_4^(2−) molar ratio was 1.77 ± 0.85. Particulate concentrations of organic acids increased with decreasing carbon number from C_9 to C_2. Organic acids were most abundant above cloud, presumably as a result of aqueous phase chemistry in cloud droplets, followed by subsequent droplet evaporation above cloud tops; the main product of this chemistry was oxalic acid. The evolution of organic acids with increasing altitude in cloud provides evidence for the multistep nature of oxalic acid production; predictions from a cloud parcel model are consistent with the observed oxalate:glyoxylate ratio as a function of altitude in GoMACCS cumuli. Suppressed organic acid formation was observed in clouds with relatively acidic droplets, as determined by high particulate nitrate concentrations (presumably high HNO_3 levels too) and lower liquid water content, as compared to other cloud fields probed. In the Houston Ship Channel region, an area with significant volatile organic compound emissions, oxalate, acetate, formate, benzoate, and pyruvate, in decreasing order, were the most abundant organic acids. Photo-oxidation of m-xylene in laboratory chamber experiments leads to a particulate organic acid product distribution consistent with the Ship Channel area observations.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1029/2007JD008537DOIArticle
http://onlinelibrary.wiley.com/doi/10.1029/2007JD008537/abstractPublisherArticle
http://onlinelibrary.wiley.com/doi/10.1029/2007JD008537/suppinfoPublisherSupporting Information
ORCID:
AuthorORCID
Sorooshian, Armin0000-0002-2243-2264
Ng, Nga L.0000-0001-8460-4765
Chan, Arthur W. H.0000-0001-7392-4237
Flagan, Richard C.0000-0001-5690-770X
Seinfeld, John H.0000-0003-1344-4068
Additional Information:Copyright 2007 by the American Geophysical Union. Received 12 February 2007; revised 17 April 2007; accepted 26 April 2007; published 3 July 2007. This work was supported by NOAA grant NA06OAR4310082.
Funders:
Funding AgencyGrant Number
National Oceanic and Atmospheric Administration (NOAA)NA06OAR4310082
Subject Keywords:organic aerosols; organic acids; clouds
Issue or Number:D3
DOI:10.1029/2007JD008537
Record Number:CaltechAUTHORS:20141028-151856371
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20141028-151856371
Official Citation:Sorooshian, A., N. L. Ng, A. W. H. Chan, G. Feingold, R. C. Flagan, and J. H. Seinfeld (2007), Particulate organic acids and overall water-soluble aerosol composition measurements from the 2006 Gulf of Mexico Atmospheric Composition and Climate Study (GoMACCS), J. Geophys. Res., 112, D13201, doi:10.1029/2007JD008537.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:50958
Collection:CaltechAUTHORS
Deposited By: George Porter
Deposited On:28 Oct 2014 23:37
Last Modified:10 Nov 2021 19:03

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