北京大气颗粒物中一元羧酸的季节变化和来源分析

Seasonal variations and sources of monocarboxylic acids in the atmospheric PM_(10) and PM_(2.5) of Beijing

通过膜采样溶剂提取、衍生化GC/MS分析,对2006年9月～2007年8月间北京大气PM10和PM2.5中的一元羧酸进行了观测研究.结果表明,可检出C10～C30的烷酸以及油酸、亚油酸和桐油酸3种烯酸,其中含量最高的是C16和C182种烷酸.PM10中,一元羧酸总浓度为61.7～1652.3ng/m3,年平均为426.2ng/m3;PM2.5中,一元羧酸总浓度为34.5～992.1ng/m3,年平均为319.6ng/m3.75%的一元羧酸分布在细粒子中,且冬、春季浓度明显高于夏、秋季.春、夏、秋、冬4个季节PM10中一元羧酸浓度分别为(625.1±403.8),(200.0±95.3),(263.0±201.1),(659.9±433.5)ng/m3;PM2.5中一元羧酸浓度为(431.7±211.0),(194.4±95.8),(207.9±160.8),(463.6±262.1)ng/m3.源解析显示,燃煤排放是冬季最主要的人为污染源;机动车排放则在其他季节贡献最大.

Monocarboxylic acids in the atmoshperic PMIo and PM2.5 of Beijing were determined by GC-MS from September 2006 to August 2007.21 n-alkanoic acids （C10-C30） and 3 alkenoic acids including oleic（C18：0, linoleic（C18：2） and eleostearic acid（C18：3） were detected, among which C16 and C18 were the most abundant. Total concentrations of monocarboxylic acids in PM10 varied from 61.7 to 1652.3ng/m^3, annual averaged 426.2ng/m^3, while in PM2.5 the concentrations ranged from 34.5 to 992.1ng/m^3, annual averaged 319.6ng/m^3. 75% of those monocarboxylic acids distributed in the fine particle. Concentrations of monocarboxylic acids in spring, summer, autumn and winter were （625.1±403.8）, （200.0±95.3）, （263.0±201.1）, （659.9± 433.5）ng/m^3 （PM10） and （431.7±211.0）, （194.4±95.8）, （207.9±160.8）, （463.6±262.1）ng/m^3 （PM25）, respectively. They were apparently higher in winter and spring than in summer and autumn.Source apportionments implied that coal burning for heating was the most important anthropogenic source in winter, while automobile exhaust contributed most in other seasons.