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Published December 16, 2006 | Published + Supplemental Material
Journal Article Open

Oxalic acid in clear and cloudy atmospheres: Analysis of data from International Consortium for Atmospheric Research on Transport and Transformation 2004


Oxalic acid is often the leading contributor to the total dicarboxylic acid mass in ambient organic aerosol particles. During the 2004 International Consortium for Atmospheric Research on Transport and Transformation (ICARTT) field campaign, nine inorganic ions (including SO_4^(2−)) and five organic acid ions (including oxalate) were measured on board the Center for Interdisciplinary Remotely Piloted Aircraft Studies (CIRPAS) Twin Otter research aircraft by a particle-into-liquid sampler (PILS) during flights over Ohio and surrounding areas. Five local atmospheric conditions were studied: (1) cloud-free air, (2) power plant plume in cloud-free air with precipitation from scattered clouds overhead, (3) power plant plume in cloud-free air, (4) power plant plume in cloud, and (5) clouds uninfluenced by local pollution sources. The aircraft sampled from two inlets: a counterflow virtual impactor (CVI) to isolate droplet residuals in clouds and a second inlet for sampling total aerosol. A strong correlation was observed between oxalate and SO_4^(2−) when sampling through both inlets in clouds. Predictions from a chemical cloud parcel model considering the aqueous-phase production of dicarboxylic acids and SO_4^(2−) show good agreement for the relative magnitude of SO_4^(2−) and oxalate growth for two scenarios: power plant plume in clouds and clouds uninfluenced by local pollution sources. The relative contributions of the two aqueous-phase routes responsible for oxalic acid formation were examined; the oxidation of glyoxylic acid was predicted to dominate over the decay of longer-chain dicarboxylic acids. Clear evidence is presented for aqueous-phase oxalic acid production as the primary mechanism for oxalic acid formation in ambient aerosols.

Additional Information

© 2006 American Geophysical Union. Received 10 November 2005; revised 11 February 2006; accepted 22 March 2006; published 26 August 2006. This work was supported by the National Science Foundation grant ATM-0340832. Graham Feingold and Barbara Ervens were supported by NOAA's Climate Goal. Elliot L. Atlas acknowledges support from the NOAA Office of Global Programs and NOAA Health of the Atmosphere Program. We thank Kurt Anlauf, Art Tham, and Maurice Watt of the Meteorological Service of Canada for providing hydrogen peroxide measurements. Appreciation is extended to William C. Conant for helpful discussions.

Attached Files

Published - 249-Sorooshian-2006.pdf

Supplemental Material - jgrd12789-sup-0001-t01.txt

Supplemental Material - jgrd12789-sup-0002-t02.txt

Supplemental Material - jgrd12789-sup-0003-t03.txt

Supplemental Material - jgrd12789-sup-0004-t04.txt


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