汽车工业区大气挥发性有机物(VOCs)变化特征及来源解析

挥发性有机物（volatile organic compounds，VOCs）作为臭氧和细颗粒物的重要前体物已日益受到关注.鲜有针对汽车工业区大气VOCs长期观测的报道.2019-01-01~2019-12-31期间在上海某汽车工业园区边界，采用在线气相色谱仪对79种VOCs组分定量检测，分析大气VOCs组成和变化特征，并利用最大增量反应活性（MIR）和·OH消耗速率法（L_·OH）估算大气化学反应活性，应用VOCs特征物比值法和主因子分析法对VOCs进行来源解析.园区大气总VOCs体积分数为26.5×10^-9，其中烷烃占比50.2%，烯烃为9.8%，芳香烃为22.4%，卤代烃为10.8%，炔烃占6.8%，呈现冬季高，夏季低的季节变化特征.园区大气VOCs总OFP为73.2×10^-9，烷烃、烯烃和芳香烃的贡献率分别为14.7%、35.9%和45.2%，总L_·OH为165.3 s^-1，其中烯烃和芳香烃的贡献率为30.4%和48.9%.化学反应活性贡献率较高的组分有间/对-二甲苯、乙烯、丙烯、甲苯和邻-二甲苯.甲苯/苯（T/B）比值和乙烷/乙炔（E/E）比值表明观测点气团新鲜，靠近污染源.园区大气VOCs主要来源为汽油尾气源（19.4%）、溶剂使用源（30.8%）、燃烧源（11.0%）、柴油使用源（8.9%）和燃气使用源（4.5%）.

Characteristics and Source Apportionment of Volatile Organic Compounds (VOCs) in the Automobile Industrial Park of Shanghai

Volatile organic compounds (VOCs) are important precursors of ozone and fine particulate matter, and have attracted more and more research attention. There are few long-term observational studies of VOCs in automobile industry parks. From January 1 to December 31,2019, 79 kinds of VOCs were quantitatively detected by on-line gas chromatograph in an automobile industrial park in Shanghai. The composition, seasonal variation, and daily variation of VOCs were analyzed. The chemical reactivity of the atmosphere was estimated using the maximum incremental reactivity (MIR) and·OH radical loss rate. The sources of VOCs were analyzed using specific pollutant ratios and factor analysis. The results showed that the total VOCs concentration was 26.53×10^-9, with alkanes, alkenes, aromatics, halo hydrocarbon, and alkynes accounting for 50.2%, 9.8%, 22.4%, 10.8%, and 6.8%, respectively. There was an obviously seasonal variation in VOCs concentrations, with the maximum occurring in winter and the minimum in summer. Ozone formation potential (OFP) was 73.2×10^-9, of which alkanes accounted for 14.7%, alkenes 35.9%, and aromatics 45.2%. The·OH radical loss rate was 165.3 s^-1, of which alkenes accounted for 30.4% and aromatics 48.9%. The components with the highest contributions to chemical reaction activity were m/p-xylene, ethylene, propylene, toluene, and o-xylene. By estimating toluene/benzene ratios (T/B) and ethane/acetylene ratios (E/E), the air mass at the observation site was fresh, site was close to the pollution source. The main sources of VOCs were gasoline exhaust emissions (19.4%), solvent use (30.8%), combustion processes (11.0%), diesel use (8.9%), and liquefied petroleum gas use (4.5%).