徐州市区O_3浓度与前体物的变化特征分析

Analysis on Variation Characteristics of Ozone Concentration and its Precursors in Urban Atmosphere of Xuzhou

以2013年1月~2016年6月份徐州市区近地层大气中臭氧(O_3)、氮氧化物(NOx)和挥发性有机物(VOCs)的监测数据,探讨徐州市区O_3浓度的变化特征以及与其前体物的关系。研究表明,徐州市区每年在5~8月份O_3浓度较高,6月份浓度最高,春夏季较高于秋冬季;O_(3-8h)浓度超标主要出现在5,6月份。O_3日浓度变化呈现单峰型,在午后达到峰值;太阳辐射强度越大,8∶00~12∶00 O_3浓度上升越明显;受太阳辐射和城市交通的影响,NOx和VOCs浓度日变化呈现双峰型;由于光化学反应的发生,NO_2和VOCs浓度与O_3浓度呈负相关性。运用VOCs/NOx比值法研究表明,在夏季徐州市区O_3的生成对VOCs较敏感,属于VOCs控制区;大气中的烷烃、烯烃和芳香烃化合物是生成O_3的主要物质。

Based on the observational data of the volume fractions of ozone, NOx and VOCs in the near surface layer were over the urban area of Xuzhou from 2013 to 2016. This research studied the characteristics of ozone concentration variation and its relationship with the concentration of the precursors. The result shows that the concentration of ozone from May to August is higher than in other months, and the highest concentration oceurredin June. In general, ozone concentration is higher, in summer and autumn than that in spring and winter, ozone concentration exceeded mainly in May and June. The diurnal variation of ozone concentration has a single peak in afternoon. With higher solar radiation intensity,ozone concentration increased from 8 to 12 in the morning. Affected by solar radiation and city traffic, the diurnal variation of NOx and VOCs has two peaks. Because of photochemical reactions, NOx and VOCs were negatively correlated with ozone concentration. VOCs / NOx discriminant method was used to get the sensitive control factors of ozone, The results showed that the ozone generation in Xuzhou urban district was sensitive to VOCs, and belonged to VOCs control area in summer. Alkanes, olefins and aromatics are the main substances generating ozone in urban atmosphere of Xuzhou.