2007年春节期间北京大气细粒子中正构烷烃的污染特征

Pollution Characteristics of n-alkanes in Atmospheric Fine Particles During Spring Festival of 2007 in Beijing

利用大流量颗粒物采样器分昼夜采集了2007年春节前后大气气溶胶中PM2.5样品,并采用气相色谱-质谱技术对PM2.5样品中的正构烷烃进行了检测和分析.结果表明,春节期间大气细粒子平均浓度全部超过WHO阈值,且夜间平均浓度要高于白天.细粒子中检测出C10～C33的正构烷烃,总浓度为201.7～2715.6ng.m-3,夜间正构烷烃的平均总浓度(943.5ng.m-3)要高于白天(581.1ng.m-3),除夕前的平均总浓度(1025.5ng.m-3)要高于除夕后(536.6ng.m-3).主峰碳为23、24和25,CPI值为0.9～1.4,平均为1.15,表明春节期间北京大气细粒子中的正构烷烃主要由化石燃料的不完全燃烧产生,%WaxCn的结果表明生物源对气溶胶中正构烷烃的贡献率为8.5%～47%.

Research PM2.5 aerosols had been carried out with sampler of high-volume sampler during Spring Festival of 2007 in Beijing, and the concentrations of n-alkane in PM2.5 samples were determined via GC-MS. The average concentrations of PM2.5 which were all exceeded WHO threshold values were higher in the night than those in the day time. The n-alkane homolog from C10 to C33 were detected with the major peak carbon numbers ranging from 23 to 25. The total concentrations of n-alkane were higher in the night （943.5 ng·m^-3 ） than those in the day time （581.1 ng·m^-3 ）. And also we found that the average concentrations of n-alkane before New Year＇s Eve（1 025.5 ng·m^-3 ） were higher than those after（536.6 ng·m^-3 ）. The CPI values were 0.9-1.4 with average of 1.15. Those results may mean that primary resource of n-alkane in fine particles was the incomplete combustion of fossil fuel. The percent contribution of leaf ＂Wax＂ n-alkane indicated that about 8.5 %-47% of n-alkane came from waxy leaf surface abrasion.