| 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, and the highest concentrations of PAN and PPN during the daytime are 2 493.2×10-12 and 509.2×10-12 respectively. A strong correlation is found between PAN and PPN, R2=0.949 5, 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 moderate correlation has been indicated between PAN and O3. |
