石家庄夏季典型时段臭氧污染特征及来源解析

Pollution Characteristic and Source Apportionment of VOCs During Summer Typical Periods in Shijiazhuang

在石家庄臭氧(O3)污染较重的7月,开展连续10 d(2018年7月6-15日),8次/d的加密监测,获得大气挥发性有机物(VOCs)苏玛罐样品数据及O3在线监测数据,分析了采样期间O3污染特征、VOCs组成及O3生成潜势(OFP)特征,并对VOCs来源进行了研究。结果表明,采样期间O3-3 h浓度最高为243μg/m^3,与相对湿度存在明显的反相关关系,与温度和风速存在良好的正相关关系。VOCs平均体积分数为(75.28±5.81)×10^-9,各组分浓度所占比例为OVOCs>烷烃>卤代烃>烯炔烃>芳香烃>其他组分。各类VOCs中,OVOCs对OFP的贡献最大,占64.12%。作为光化学反应的中间产物,OVOCs的一次来源较少,表明二次污染物对石家庄大气O3生成有重要贡献。从具体组分来看,OFP值排名前十的组分以OVOCs为主,其中最高的为甲基丙烯酸甲酯。采样期间,VOCs一次来源主要为汽油车和柴油车尾气排放,贡献率分别为38%与32%;溶剂使用、汽油挥发、生物排放分别占13%、11%、6%。VOCs主要受本地排放影响。

During a serious ozone pollution period, a 10 days(July 6-15, 2018) consecutive sampling campaign of VOCs with suma canister and on-line monitoring of O3 was carried out with 8 times per day in Shijiazhuang. The characteristics of O3 pollution, VOCs composition and Ozone Formation Potential(OFP) during the sampling period were analyzed, and the sources of VOCs were analyzed. The results shows that the highest concentration of O3-3 h is 243 μg/m^3 during sampling, which has a strong inverse correlation with relative humidity and a strong positive correlation with temperature and wind speed. The average volume fraction of VOCs is 75.28±5.81×10^-9, with the concentrations of various substances of OVOCs>alkanes>halogenated hydrocarbons>alkynes>aromatic hydrocarbons > other components. OVOCs was the primary contributor of OFP with 64.12%. The top 10 species of OFP value were mainly OVOCs, and the highest was methyl methacrylate. Secondary pollutants played an important role in ozone generation in Shijiazhuang. During the sampling period, the primary source of VOCs mainly comes from the exhaust emissions of gasoline and diesel vehicles, accounting for 38% and 32% respectively. Solvent use, gasoline volatilization and biological emissions accounted for 13%, 11% and 6% respectively. And, VOCs are mainly affected by local emissions.