Trans-hemispheric contribution of C 2 -C 10 α, ω-dicarboxylic acids, and related polar compounds to water-soluble organic carbon in the western Pacific aerosols in relation to photochemical oxidation reactions

Richard Sempere (1) , Kimitaka Kawamura (2)

1 MIO - Institut méditerranéen d'océanologie
2 Institute of Low-Temperature Science

Marine aerosol samples were collected during a western Pacific cruise covering the latitude range between 35°N and 40°S (140°E-180°E). They were analyzed for total carbon (TC), total nitrogen (TN), water-soluble organic carbon (WSOC) along with the molecular distributions of C 2-C 10 a, w-dicarboxylic acids, and related polar compounds, mainly, w-oxocarboxylic acids (C 2-C 9) and a-dicarbonyls (C 2-C 3). Oxalic acid (C 2) was the most abundant followed by malonic (C 3) and succinic (C 4) acids. The total diacid concentration range was 7-605 ng m À3 (av. 85 ng m À3) and the diacid-carbon accounted for 2-15% (average 8%) of WSOC which comprised 29-55% (average 40%) of TC. Dry depositions of total diacids over the northern and southern Pacific Ocean were estimated to be 256-1907 mg m À2 yr À1 (average 735; n = 4) and 22-396 mg m À2 yr À1 (average 134; n = 14), respectively, whereas the air-to-sea flux of oxalic acid was 18-1351 mg m À2 yr À1 (average 466 mg m À2 yr À1) and 7.5-275 mg m À2 yr À1 (average 75 mg m À2 yr À1) in the Northern and Southern Hemispheres. We observed that the concentration ratios of diacid-C/WSOC, azelaic acid (C 9)/w-oxononanoic acid, maleic acid (iC 4 cis)/fumaric (iC 4 trans) acid and succinic acid (C 4)/ total diacids were correlated with air temperature. These findings showed that the intensity of photochemical oxidation reactions and thus the variation in sunlight intensity characterized here by air temperature, significantly control the molecular distribution of water-soluble organic compounds during the long-range transport of anthropogenic and/or biogenic higher molecular weight organic compounds. Citation: Sempéré, R., and K. Kawamura, Trans-hemispheric contribution of C 2-C 10 a, w-dicarboxylic acids, and related polar compounds to water-soluble organic carbon in the western Pacific aerosols in relation to photochemical oxidation reactions,

Mots clés: diacids; water-soluble organic compounds; atmospheric chemistry; aerosols; Atmospheric Composition and Structure: Aerosols and particles; Atmospheric Composition and Structure: Air/sea constituent fluxes; Atmospheric Composition and Structure: Chemical kinetic and photochemical properties; Atmospheric Composition and Structure: Cloud physics and chemistry; western Pacific

Domaines: Océan, Atmosphère

Richard Sempere, Kimitaka Kawamura. Trans-hemispheric contribution of C 2 -C 10 α, ω-dicarboxylic acids, and related polar compounds to water-soluble organic carbon in the western Pacific aerosols in relation to photochemical oxidation reactions. Global Biogeochemical Cycles, 2003, 17 (2), pp.n/a-n/a. ⟨10.1029/2002gb001980⟩. ⟨hal-01999294⟩