Dicarboxylic acids and related compounds in PM 2.5 aerosols in Huangshi, central China.

PM2.5 samples were collected in Huangshi (HS), central China from March 2012 to February 2013 and were analyzed for dicarboxylic acids (diacids) and related compounds (DARCs). Oxalic acid (C2 , 416 ng m-3 ) was the most abundant species, followed by phthalic (Ph, 122 ng m-3 ), terephthalic (tPh, 116 ng m-3 ), succinic (C4 , 70.4 ng m-3 ), azelaic (C9 , 67.9 ng m-3 ) and adipic (C6 , 57.8 ng m-3 ) acids . Relatively high abundances of Ph and tPh differed from the distribution in urban and marine aerosols, indicating contributions from nearby anthropogenic sources. Glyoxylic acid (ωC2 , 41.4 ng m-3 ) was the dominant oxoacid, followed by 9-oxononanoic (ωC9 , 40.8 ng m-3 ) and pyruvic (Pyr, 24.1 ng m-3 ) acids. Glyoxal (Gly, 35.5 ng m-3 ) was the dominant α-dicarbonyl. Highest average concentrations were found for C2 , ωC2 and C9 in autumn, for C4 , Pyr and C6 in spring, for Ph, ωC9 and Gly in summer, while the lowest values were observed in winter. Seasonal variations and correlation coefficients of DARCs demonstrate that both primary emissions and secondary production are important sources. Principal component analysis of selected DARCs species suggests that a mixing of air masses from anthropogenic and biogenic sources contribute to the HS aerosols.