Open AccessStable carbon isotopic compositions of total carbon, dicarboxylic acids and glyoxylic acid in the tropical Indian aerosols: Implications for sources and photochemical processing of organic aerosols
Author(s) -
Pavuluri Chandra Mouli,
Kawamura Kimitaka,
Swaminathan T.,
Tachibana Eri
Publication year - 2011
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2011jd015617
Subject(s) - aerosol , total organic carbon , succinic acid , δ13c , environmental chemistry , dicarboxylic acid , carbon fibers , oxalic acid , phthalic acid , chemistry , stable isotope ratio , organic chemistry , materials science , composite number , composite material , physics , quantum mechanics
The tropical Indian aerosols (PM 10 ) collected on day‐ and nighttime bases in winter and summer, 2007 from Chennai (13.04°N; 80.17°E) were studied for stable carbon isotopic compositions ( δ 13 C) of total carbon (TC), individual dicarboxylic acids (C 2 ‐C 9 ) and glyoxylic acid ( ω C 2 ). δ 13 C values of TC ranged from −23.9‰ to −25.9‰ (−25.0 ± 0.6‰; n = 49). Oxalic (C 2 ) (−17.1 ± 2.5‰), malonic (C 3 ) (−20.8 ± 1.8‰), succinic (C 4 ) (−22.5 ± 1.5‰) and adipic (C 6 ) (−20.6 ± 4.1‰) acids and ω C 2 acid (−22.4 ± 5.5‰) were found to be more enriched with 13 C compared to TC. In contrast, suberic (C 8 ) (−29.4 ± 1.8‰), phthalic (Ph) (−30.1 ± 3.5‰) and azelaic (C 9 ) (−28.4 ± 5.8‰) acids showed smaller δ 13 C values than TC. Based on comparisons of δ 13 C values of TC in Chennai aerosols to those (−24.7 ± 2.2‰) found in unburned cow‐dung samples collected from Chennai and isotopic signatures of the particles emitted from point sources, we found that biofuel/biomass burning are the major sources of carbonaceous aerosols in South and Southeast Asia. The decrease in δ 13 C values of C 9 diacid by about 5‰ from winter to summer suggests that tropical plant emissions also significantly contribute to organic aerosol in this region. Significant increase in δ 13 C values from C 4 to C 2 diacids in Chennai aerosols could be attributed for their photochemical processing in the tropical atmosphere during long‐range transport from source regions.