[Compositions and Sources of Summertime Dicarboxylic Acids and Related SOA in PM_2.5 from Mt. Taishan]

To identify the compositions and sources of dicarboxylic acids and related SOA in Mt. Taishan, PM_2.5 samples were collected from July to August, 2004, and analyzed for dicarboxylic acids and related compounds, the tracers of biogenic secondary organic aerosol (SOA) (Isopene, α-/β-Pinene and β-caryophyllene SOA tracers), water-soluble organic carbon (WSOC) and inorganic ions. The results showed that total dicarboxylic acids were (376±189) ng·m^-3, and C₂ was the most abundant dicarboxylic acid, followed by C₃, C₄ and C₉. The concentrations of diacids were more abundant than those in marine regions, but lower than those in urban and other mountainous areas, indicating that the atmosphere in Mt. Taishan was less influenced by anthropogenic pollution. C₂/C₄, C₃/C₄ and F/M ratios indicated that diacids were mostly produced by more intensive photochemical oxidation. The relative abundance of C₉ to the total diacids, C₉/C₆ and C₉/Ph ratios were higher than those in urban, marine and mountainous regions, further suggesting that SOA in Mt. Taishan atmosphere were mostly derived from biogenic sources rather than anthropogenic sources. Compared to the budgets of model and correlation analysis, it suggested that diacids and related SOA in Mt. Taishan were mostly derived from photochemical oxidation of local biogenic sources.