期刊
ENVIRONMENTAL SCIENCE & TECHNOLOGY
卷 46, 期 9, 页码 4783-4791出版社
AMER CHEMICAL SOC
DOI: 10.1021/es204322c
关键词
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资金
- China Natural Science Foundation [40873083]
- Chinese Academy of Sciences [KZCX2-YW-148]
- Ministry of Environment, Japan [B-0903]
- Institute of Low Temperature Science of Hokkaido University, Japan
Size-resolved airborne particles (9-stages) in urban Xi'an, China, during summer and winter were measured for molecular distributions and stable carbon isotopic compositions of dicarboxylic acids, ketocarboxylic acids, and alpha-dicarbonyls. To our best knowledge, we report for the first time the size-resolved differences in stable carbon isotopic compositions of diacids and related compounds in continental organic aerosols. High ambient concentrations of terephthalic (tPh, 379 +/- 200 ng m(-3)) and glyoxylic acids (omega C-2, 235 +/- 134 ng m(-3)) in Xi'an aerosols during winter compared to those in other Chinese cities suggest significant emissions from plastic waste burning and coal combustions. Most of the target compounds are enriched in the fine mode (<2.1 mu m) in both seasons peaking at 0.7-2.1 mu m. However, summertime concentrations of malonic (C-3), succinic (C-4), azelaic (C-9), phthalic (Ph), pyruvic (Pyr), 4-oxobutanoic (omega C-4), and 9-oxononanoic (omega C-9) acids, and glyoxal (Gly) in the coarse mode (>2.1 mu m) are comparable to and even higher than those in the fine mode (<2.1 mu m). Stable carbon isotopic compositions of the major organics are higher in winter than in summer, except oxalic acid (C-2), omega C-4, and Ph. delta C-13 of C-2 showed a clear difference in sizes during summer, with higher values in fine mode (ranging from -22.8 parts per thousand to -21.9 parts per thousand) and lower values in coarse mode (-27.1 parts per thousand to -23.6 parts per thousand). The lower delta C-13 of C-2 in coarse particles indicate that coarse mode of the compound originates from evaporation from fine mode and subsequent condensation/adsorption onto pre-existing coarse particles. Positive linear correlations of C-2, sulfate and omega C-2 and their delta C-13 values suggest that omega C-2 is a key intermediate, which is formed in aqueous-phase via photooxidation of precursors (e.g., Gly and Pyr), followed by a further oxidation to produce C-2.
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