WATER SOLUBLE DICARBOXYLIC ACIDS IN THE AEROSOLS FROM ASIAN REGIONS

Aerosol particles were collected on a quartz fiber filters using a high-volume air sampler during Asian Regional Aerosol Characterization Experiment (ACE-Asia) in spring to autumn 2001 at two sites; Kosan site on Cheju Island, South Korea, and Sapporo, Hokkaido Island, Japan. Dicarboxylic acids were extracted from the filters with pure water, derivatized with 14% BF3/n-butanol to dicarboxylic acid dibutyl esters, and then analyzed using a capillary GC and GC/MS. The samples were also analyzed for total organic carbon and total nitrogen as well as their stable isotopic compositions. Thirteen dicarboxylic acids (C2-C11) including unsaturated structures were detected in the aerosol samples, with oxalic (C2) acid being the most abundant species followed by malonic (C3) or succinic (C4) acids. The total concentrations (130-1300 ng m-3) are equivalent to those reported for urban Tokyo aerosols, but are much greater than those reported for marine aerosols in the North Pacific. Throughout the campaign, very high concentration of dusts (up to 440 mg m-3) and water-soluble dicarboxylic acids were often observed in early spring (e.g., April 10-11 and 24-25) at both Kosan and Sapporo. However, their concentrations did not show a very good correlation. Although both dusts and diacids are derived from the Asian continent, they originate from different sources and source regions. Diacids and their precursors are probably emitted from urban areas in East Asia whereas dusts are derived from the arid regions. This study suggests that a photochemical production of water-soluble organic acids is significant in the East Asia/North Pacific rim.