杭州秋季大气VOCs变化特征及化学反应活性研究

2017年9月1日至11月30日采用Syntech Spectras GC955在线气相色谱仪对杭州市不同功能区大气环境中的挥发性有机化合物(VOCs)进行了在线连续监测,分析了不同功能区VOCs及各组分的体积分数、日变化规律及大气化学反应活性。结果显示,下沙周边工业区总VOCs浓度整体高于朝晖周边居民区,其中夜间更为显著。烷烃和芳香烃浓度在夜间时段工业区较居民区高得更为明显,其中芳香烃组分表现尤为突出,2个功能区烯烃体积分数相差不大。杭州市主要VOCs体积分数总体上在国内处于中间水平。不同功能区烷烃和芳香烃均呈现夜间浓度高于白天的日变化特征,居民区各VOCs组分日变化基本呈现双峰结构,工业区烷烃和芳香烃体积分数日变化呈现单峰结构,烯烃体积分数没有明显的日变化特征。不同功能区中芳香烃对臭氧生成潜势贡献最大,烯烃次之,烷烃贡献最小。下沙周边工业区大气化学活性(尤其是芳香烃组分)较朝晖周边居民区强。同种VOCs物质在不同功能区对臭氧生成潜势的贡献大小不同,但关键贡献物质均为低碳烷烃、低碳烯烃及苯系物。

Variation Characteristics and Chemical Reactivity of VOCs in Different Functional Zones of Hangzhou in Autumn

A continuous observation campaign was carried out with the Syntech Spectras GC955 volatile organics online monitoring system from September 1,2017 to November 30,2017 in the different functional zones of Hangzhou. Volume fraction,diurnal variation and atmospheric chemical reactivity of VOCs and their components in different functional areas were analyzed. The results showed that the hourly average mixing ratio of the TVOCs in the industrial zones around Xiasha Station was higher than residential zones around Zhaohui Station,especially at night. The hourly average mixing ratio of alkanes and aromatics in the industrial zones was significantly higher than that in the residential zones at night,especially in aromatic hydrocarbons,and the hourly average mixing ratio of olefins in the two functional zones was not much different. The volume concentration of major VOCs in Hangzhou was generally at the intermediate level in China. The diurnal variations of alkanes and aromatics in different functional zones were higher at night than at daytime. The diurnal variation of VOCs in residential zones basically showed a bimodal structure. The diurnal variation of alkanes and aromatics in industrial zones showed a unimodal structure,and there was no obvious diurnal variation of olefin. The contribution of aromatics to ozone formation potential was the greatest in different functional zones,followed by olefins and alkanes. The atmospheric chemical activity in the industrial zones around Xiasha was stronger than that in the residential zones around Zhaohui,especially the aromatic hydrocarbons. The contribution of the same VOCs to OFP in different functional zones was different,and the key contributors were low-carbon alkanes,low-carbon olefins and benzene series.