中文摘要：

2004年和2005年秋季，在北京325m气象塔的8，80，240m 3个不同高度，对PM10和PM2.5的质量浓度分别进行了实时观测．结果表明，2004年10月1日-11月30日PM10和PM2.5的平均浓度分别为155，97μg／m^3，PM2.5/PM10为62％；2005年10月1日-11月30日PM10和PM2．5的平均浓度分别为174，87μg／m^3，PM2.5/PM10为50％．超过国家二级标准150μg／m^3（日平均值）的天数，2004年为27d,2005年为32d；超标日中,PM2.5/PM10为60％，距地面8-80m的气溶胶混合均一，但与240m相比，浓度有明显分层结构，特别是夜晚，240m的PM2.5和PM10分别低于80m以下15％和29％．夜晚100,200m附近强逆温层、风速和风向的变化是气溶胶近地层垂直分层结构形成的重要原因．

英文摘要：

In autumn of 2004 and 2005 there are 3 different heights 8, 80, 240m in 325m meteorological tower in Beijing, actual time variation was carried out on mass concentration of PM10 and PM2.5 respectively. From October to November, 2004, the average PM10 and PM2.5 concentrations were 155,97μg/m^3, and PM2.5/PM10 were 62%; while those were 174, 87μg/m^3 from October to November, 2005, and PM2.5/PM10 were 50%. Exceeding the national second degree standard 150μg/m^3 （daily average value） was 27 days in 2004, 32 days in 2005. In exceeding standard day, PM2.5/PM10 was 60%, 8-80m the Beijing atmospheric aerosol mixed uniform, but compared with 240m, the concentration had obvious layer separation structure, especially at night. PM2.5 and PM10 of 240m were lower than 80m 15% and 29% respectively. At night, near 100, 200m, the change of strong inversion layer, wind speed and wind direction were the important reason of forming the aerosol near land stratum vertical layer separation structure.