Water soluble dicarboxylic acids and related compounds in Antarctic aerosols

Antarctic aerosols collected at Syowa Station were studied for water soluble organic compounds by employing a water extraction and dibutyl ester derivatization and using a capillary gas chromatography (GC) and GC/mass spectrometry (GC/MS). Total carbon and nitrogen were also determined. A homologous series of alpha,omega-dicarboxylic acids (C-2-C-11), omega-oxocarboxylic acids (C-2-C-9), and alpha-dicarbonyls (C-2-C-3) were detected, as well as pyruvic acid and aromatic (phthalic) diacid. Succinic (C-4) or oxalic (C-2) acid was found to be the dominant diacid species, followed by azelaic (C-9), adipic (C-6), or malonic (C-3) acid, Concentration range of the total diacids was 5.9-88 ng m(-3), with an average of 29 ng m(-3). Highest concentrations were observed in the summer sample with a predominance of succinic acid (61.5 ng m(-3)), which comprised approximately 70% of the total diacids and accounted for 3.5% of total aerosol carbon (1020 ng m(-3)). The succinic acid (C-4) is likely produced by photooxidation of 4-oxocarboxylic acids, which are present in the atmosphere as intermediates of the photooxidation of unsaturated fatty acids. These results indicate that the Antarctic organic aerosols originate from marine-derived lipids and are transformed largely by photochemical oxidations. omega-Oxocarboxylic acids (C-2-C-9, 0.36-3.0 ng m(-3)) also showed the highest concentration in the summer sample, again suggesting a secondary production in the atmosphere of the Antarctic and in the Southern Ocean.