84th AMS Annual Meeting

Monday, 12 January 2004: 10:30 AM
Oxalic acid production in the coastal marine atmosphere
Room 612
Kathleen K. Crahan, University of Washington, Seattle, WA; and D. Hegg, D. S. Covert, and H. Jonsson
Poster PDF (280.7 kB)
Oxalic acid is the most abundant dicarboxylic acid found in the troposphere, yet there is still no scientific consensus concerning its origins nor its formation process. Recent studies have suggested mechanisms for its formation in cloud water from gaseous precursors. Filter samples and cloud water samples were taken from the Twin Otter aircraft during CARMA, a field campaign designed to study the marine stratocumulus off the coast of the Monterey, CA in August and September of 2002. Analysis of the filters collected by a five stage Micro-Orifice Uniform Deposit Impactor (MOUDI) revealed a peak in the concentration distribution at a diameter of 0.26 to 0.44 micrometers, similar to the size distribution found for non sea salt sulfate. Further supporting the idea that oxalate is formed through reactions in cloud liquid water in a manner similar to nss sulfate is that both anions were found in excess in cloud water as compared to below cloud filter samples, at cloud water to filter ratios of 2.4 0.5 for nss sulfate mass, and 3.0 0.4 for oxalate mass. Model calculations will be presented demonstrating the feasibility of cloud water production of oxalate.

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