TY - JOUR
T1 - Seasonal characteristics of oxalic acid and related SOA in the free troposphere of Mt. Hua, central China
T2 - Implications for sources and formation mechanisms
AU - Meng, Jingjing
AU - Wang, Gehui
AU - Li, Jianjun
AU - Cheng, Chunlei
AU - Ren, Yanqin
AU - Huang, Yao
AU - Cheng, Yuting
AU - Cao, Junji
AU - Zhang, Ting
N1 - Publisher Copyright:
© 2014 Elsevier B.V.
PY - 2014/9/5
Y1 - 2014/9/5
N2 - PM10 aerosols from the summit of Mt. Hua (2060ma.s.l) in central China during the winter and summer of 2009 were analyzed for dicarboxylic acids, ketocarboxylic acids and α-dicarbonyls. Molecular composition of dicarboxylic acids (C2-C11) in the free tropospheric aerosols reveals that oxalic acid (C2, 399±261ngm-3 in winter and 522±261ngm-3 in summer) is the most abundant species in both seasons, followed by malonic (C3) and succinic (C4) acids, being consistent with that on ground levels. Most of the diacids are more abundant in summer than in winter, but adipic (C6) and phthalic (Ph) acids are twice lower in summer, suggesting more significant impact of anthropogenic pollution on the wintertime alpine atmosphere. Moreover, glyoxal (Gly) and methylglyoxal (mGly) are also lower in summer (12±6.1ngm-3) than in winter (22±13ngm-3). As both dicarbonyls are a major precursor of C2, their seasonal variation patterns, which are opposite to those of the diacids, indicate that the mountain troposphere is more oxidative in summer.C2 showed strong linear correlations with levoglucosan in winter and oxidation products of isoprene and monoterpene in summer. PCA analysis further suggested that the wintertime C2 and related SOA in the Mt. Hua troposphere mostly originate from photochemical oxidations of anthropogenic pollutants emitted from biofuel and coal combustion in lowland regions. On contrast, the summertime C2 and related SOA mostly originate from further oxidation of the mountainous isoprene and monoterpene oxidation products. The AIM model calculation results showed that oxalic acid concentration well correlated with particle acidity (R2=0.60) but not correlated with particle liquid water content, indicating that particle acidity favors the organic acid formation because aqueous-phase C2 production is the primary mechanism of C2 formation in ambient aerosols and is driven by acid-catalyzed oxidation.
AB - PM10 aerosols from the summit of Mt. Hua (2060ma.s.l) in central China during the winter and summer of 2009 were analyzed for dicarboxylic acids, ketocarboxylic acids and α-dicarbonyls. Molecular composition of dicarboxylic acids (C2-C11) in the free tropospheric aerosols reveals that oxalic acid (C2, 399±261ngm-3 in winter and 522±261ngm-3 in summer) is the most abundant species in both seasons, followed by malonic (C3) and succinic (C4) acids, being consistent with that on ground levels. Most of the diacids are more abundant in summer than in winter, but adipic (C6) and phthalic (Ph) acids are twice lower in summer, suggesting more significant impact of anthropogenic pollution on the wintertime alpine atmosphere. Moreover, glyoxal (Gly) and methylglyoxal (mGly) are also lower in summer (12±6.1ngm-3) than in winter (22±13ngm-3). As both dicarbonyls are a major precursor of C2, their seasonal variation patterns, which are opposite to those of the diacids, indicate that the mountain troposphere is more oxidative in summer.C2 showed strong linear correlations with levoglucosan in winter and oxidation products of isoprene and monoterpene in summer. PCA analysis further suggested that the wintertime C2 and related SOA in the Mt. Hua troposphere mostly originate from photochemical oxidations of anthropogenic pollutants emitted from biofuel and coal combustion in lowland regions. On contrast, the summertime C2 and related SOA mostly originate from further oxidation of the mountainous isoprene and monoterpene oxidation products. The AIM model calculation results showed that oxalic acid concentration well correlated with particle acidity (R2=0.60) but not correlated with particle liquid water content, indicating that particle acidity favors the organic acid formation because aqueous-phase C2 production is the primary mechanism of C2 formation in ambient aerosols and is driven by acid-catalyzed oxidation.
KW - Dicarboxylic acids
KW - Free troposphere
KW - Glyoxal and methylglyoxal
KW - Seasonality
KW - Secondary organic aerosols
KW - Sources and formation mechanisms
UR - https://www.scopus.com/pages/publications/84904745863
U2 - 10.1016/j.scitotenv.2014.04.086
DO - 10.1016/j.scitotenv.2014.04.086
M3 - 文章
C2 - 24925591
AN - SCOPUS:84904745863
SN - 0048-9697
VL - 493
SP - 1088
EP - 1097
JO - Science of the Total Environment
JF - Science of the Total Environment
ER -