[Variation characteristics of surface ozone and its precursors during summertime in Nanjing northern suburb].

It is not optimistic about current air quality in Nanjing northern suburb, an area with the agglomeration of heavy industry such as steel-making and petrochemical industry. Measurement of ozone and its precursors conducted from May 18th to August 31st, with the Meteorological data recorded simultaneously, were analyzed to characterize the local photochemical pollution in summertime. The results showed that the average volume fraction of ozone (O3), nitrogen oxide (NO(x)) and volatile organic compounds (VOCs) in Nanjing northern suburb was about (32.01 ± 15.20) x 10(-9), (21.50 ± 14.02) x 10(-9) and (33.16 ± 25.20) x 10(-9), respectively, and carbon monoxide (CO) was (0.66 ± 0.44) x 10(-6). For O3, the maximum value reached 146.42 x 10(-9), exceeding the National Ambient Air Quality Standard II by a rate of 14.1%. The background level of O3, NO(x), VOCs and CO were estimated to be (5.71 ± 2.51) x 10(-9), (12.20 ± 0.36) x 10(-9), (22.44 ± 0.38) x 10(-9) and (0.28 ± 0.01) x 10(-6), respectively, from the frequency distribution of their hourly averaged volume fraction. Pollutants were significantly affected by local emission sources near the site. When affected by the southwest wind with the speed of 2-3 m x s(-1), active species of VOCs were easy to reach high level, accompanied by an increased concentration of O3; Under the influence of easterly winds, NO(x), CO and VOCs, mainly emitted from industrial sources and traffic sources, were prone to reach high level. The regulation and control measures were taken on industrial production and some vehicles during the Nanjing Asian Youth Games, but the concentration of O3 was not significantly reduced, and there were 4 days exceeding the National Ambient Air Quality Standard II.