Monitoring and Analysis of PAN and PPN in the Air of Beijing During the Summer of 2005
夏季北京市大气中PAN与PPN的监测分析

PAN and PPN in the urban air of Beijing were monitored by using a online instrument from Aug.15th to Aug.28th, 2005. The results show that the concentrations of PAN and PPN are extremely high in the air of the city area of Beijing, the highest concentrations of PAN and PPN during the daytime are 2493.2×10-12 and 509.2 ×10-12 respectively. A strong correlation was found between PAN and PPN, R2=0.9495, and the average ratio of PPN]/PAN] is about 20.2%, which suggests anthropogenic VOCs are dominant when compared to biogenic ones in the urban air. The precipitation has strong negative effects on the formation and accumulation of PAN and PPN. High concentrations of PAN and PPN occur every midnight. During day time, high concentrations of PAN and PPN occurred with high concentrations of NO2 when NO concentrations are fairly low. Diurnal variations of O3 and PAN are very similar to each other, and a correlation has been indicated between PAN and O3.