[Seasonal Variations in PM 10 and Associated Chemical Species in Jiuxian Mountain in Fujian Province].

PM samples were collected at the top of Jiuxian Mountain in Fujian Province from March 2011 to January 2012 and were analyzed for inorganic water-soluble ions and dicarboxylic acids to investigate their seasonal variations and sources. The results showed that PM and its associated species exhibited much higher levels in the spring than those in other seasons but the total contribution of the nine species of dicarboxylic acids to PM (0.51%±0.41%) was significantly lower than that of the water-soluble ions (18.07%±8.73%). The water-soluble ions were characterized by the highest concentrations of SO and NO, followed by Na and NH. Significant positive correlations were observed between cation and anion equivalents, as well as between NH and SO or NO equivalents. Individual dicarboxylic acid showed a monotonically decreasing trend with increasing carbon number in which oxalic acid accounted for approximately 75% of the total dicarboxylic acids. Characteristic ratios of malonic acid to succinic acid and adipic acid to azelaic acid, MODIS fire spots, and backward trajectories showed that dicarboxylic acids mainly originated from secondary reactions in the atmosphere and that the direct contributions of open biomass burning to dicarboxylic acid concentrations were negligible.