Trans‐hemispheric contribution of C₂–C₁₀α, ω‐dicarboxylic acids, and related polar compounds to water‐soluble organic carbon in the western Pacific aerosols in relation to photochemical oxidation reactions

Abstract

[1] 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 diacidcarbon 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 )/woxononanoic 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,

Photoinduced oxidation of sea salt halides by aromatic ketones: a source of halogenated radicals

“…The k q values are in reasonably good agreement with the values obtained by Hurley et al (1988) and Shizuka et al (1982) in aqueous and acetonitrile media. The difference (20-50%) is probably due to an ionic strength effect (Douglas et al, 1990;Morrison et al, 1996) or to a solvent effect (Burget and Jacques, 1998;Gutierrez, 2008).…”

“…The errors given as 95% confidence intervals estimated from the data fits. (Murov et al, 1993) G ET (eV) IpH=5.5 water pH=11 water acetonitrile/water (8.2±0.8)×10 9 this work 2.3×10 9 (Hurley et al, 1988) 3.5×10 9 (Shizuka and Obuchi, 1982) (…”

“…The predominant anion is chloride (with concentrations approaching 0.5-5.6 M); followed by bromide (∼10 mM) and iodide at least (∼1 µM) (von Glasow et al, 2003;Schweitzer et al, 2000). While halide anions are very stable, their corresponding oxidized forms (i.e., halogen atoms) are highly reactive and play an important role in the oxidation capacity of the MBL as discovered for the Arctic boundary layer (Barrie et al, 1988).…”

“…The ocean's surface microlayer is particularly enriched in organics as revealed by chemical analysis, including amino acids, proteins, fatty acids, lipids, phenols, PAHs, and humic-type components (Cincinelli et al, 2001a, b). Such a complex chemical mixture is naturally reactive with a variety of functional groups, such as carbonyl and carboxylic acids (Sempere and Kawamura, 2003). The sea surface microlayer often has greater…”

Aerosol and snow transfer processes: An investigation on the behavior of water-soluble organic compounds and ionic species

“…S1), they may provide useful information based on their composition and particle size distributions. CA are major contributors to organic aerosol mass (Sempere and Kawamura, 2003). The total mean concentration of CA in our PM 10 samples was 0.8 ± 0.5 ng m À3 , the mean concentrations reported are associated with a high standard deviations due to the very low concentrations in Antarctic samples.…”