深圳臭氧污染日的VOCs组成与来源特征

由于挥发性有机物（VOCs）是O₃生成的关键前体物，因此了解VOCs的污染特征以及主要来源对控制O₃污染具有重要的意义.本研究于2019年9~10月在深圳市开展了在线VOCs观测，共计监测104个物种.观测期间，臭氧超标率达17.8%.TVOCs总浓度为38.9×10^-9，污染日浓度明显高于非污染日.从大类物种来看，浓度从高到低依次为烷烃>含氧有机物（OVOCs）>卤代烃>芳香烃>烯烃>乙炔>乙腈，臭氧生成潜势（OFP）中芳香烃、OVOCs以及烯烃贡献较大.由PMF源解析模型分析结果可知，VOCs主要来源包括生物质燃烧、汽油挥发、机动车尾气、工业过程以及溶剂使用等，而其中对OFP贡献较大的排放源为溶剂使用（45.8%）、机动车尾气（27.3%）.臭氧污染日发生时，清晨低风速可能导致了机动车尾气与汽油挥发源在交通早高峰快速积累，而当日高温亦会加快汽油源与溶剂源组分挥发并促进光化学反应.

The characterization and source apportionment of VOCs in Shenzhen during ozone polluted period

Since volatile organic compounds (VOCs) are the key precursors of O₃ formation, it's important to study on the characteristic and major source of VOCs for controlling O₃ pollution. The research conducted an online VOCs observation from 6^th September to 31^th October in 2019, accounting for 104species was monitored. During the observation, the Over-standard rate of ozone was up to 17.8%. The mixing ratio of TVOCs was about 38.9×10^-9, and polluted period was much higher than non-polluted period. Alkane was the most abundant species at the observation set, followed by OVOC, halohydrocarbon, aromatic, alkene, acetylene and acetonitrile, while aromatic, oxygenated volatile organic compounds (OVOCs) and alkene contributed most for ozone formation potential(OFP). Based on the analysis of PMF source apportionment model, the main sources of VOCs in Shenzhen were biomass burning, gasoline volatilization, vehicle exhaust, industry process and solvent usage, while solvent usage (45.8%) and vehicle exhaust (27.3%) contributed most to the OFP. During the polluted ozone period, weak wind speed may enhance the accumulation of vehicle exhaust and gasoline volatilization source at morning traffic rush time, while the high temperature will also accelerate the evaporation of components in gasoline source and solvent source and promote the photochemical reaction.