北京PM2.5浓度的变化特征及其与PM10、TSP的关系

在连续2年进行累积1周同步采样的基础上,对北京市城区和居住区2个采样点环境空气中PM2.5的浓度及其时间变化特征进行了分析.PM2.5周平均浓度的变化范围为37~346靏/m3,年均浓度接近或超过PM10的二级年均标准.PM2.5浓度具有明显的季节变化特征,即冬季最高,夏季最低.2个采样点PM2.5浓度的周变化与季节变化均相似.PM2.5与PM10、TSP的比值均在冬季最高,春季最低,反映采暖燃烧源对细颗粒物的贡献较大,而沙尘天气对粗颗粒物的贡献较大;其年均值分别为55%和29%.

Variation characteristics of PM2.5 concentration and its relationship with PM10 and TSP in Beijing

Based on two years simultaneous one-week integrated sampling, in two downtown/residential sampling sites in Beijing, PM2.5 concentration and its temporal variation feature in ambient air were analyzed. Weekly PM2.5 average concentrations ranged from 37 to 346mg/m3 and the annual average was near or over the second class annual average standard of PM10. PM2.5 concentration possessed markedly the variation feature with highest in winter and lowest in summer. Weekly and seasonal variations of PM2.5 concentrations were similar between the two sampling sites. Both PM2.5 to PM10 and PM2.5 to TSP ratios were highest in winter and lowest in spring, reflecting heating combustion sources contributed more to fine particles, while dust weather did more to coarse particles. Annul averages of PM2.5/PM10 and PM2.5/TSP were 55% and 29% respectively.