福建九仙山大气PM10及部分化学组成的季节变化

于2011年3月~2012年1月期间在福建德化县九仙山气象站采集大气PM_(10)样品,分析了九仙山大气PM_(10)中水溶性离子及二元羧酸,对其季节分布与来源进行了探讨.结果表明,九仙山大气PM_(10)、水溶性无机离子和有机二元羧酸的季节分布规律较为接近,都表现为春季的浓度显著高于其它季节,但9种二元羧酸对PM_(10)的贡献(0.51%±0.41%)显著低于水溶性离子(18.07%±8.73%).其中,水溶性离子组成以NO_3~-和SO_4~(2-)的浓度为最高,其次为Na~+和NH_4~+;阴离子与阳离子当量浓度、NH_4~+与SO_4~(2-)当量浓度,以及NH_4~+与NO_3~-当量浓度之间都存在显著正相关关系.有机二元羧酸的组成以乙二酸的浓度为最高,占测量二元羧酸总量的75%左右,且随碳数增加呈逐渐递减趋势;来源特征比值(丙二酸/丁二酸、己二酸/壬二酸)、MODIS火点图及后向轨迹图显示,有机二元羧酸主要来自大气二次化学反应过程,生物质燃烧的直接贡献很小.

Seasonal Variations in PM10 and Associated Chemical Species in Jiuxian Mountain in Fujian Province

PM₁₀ 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 PM₁₀ 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 PM₁₀ (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 SO₄^2- and NO₃^-, followed by Na⁺ and NH₄⁺. Significant positive correlations were observed between cation and anion equivalents, as well as between NH₄⁺ and SO₄^2- or NO₃^- 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.