南京城区夏季大气VOCs的来源及对SOA的生成研究——以亚青和青奥期间为例

运用大气挥发性有机物快速在线连续自动监测系统，于2013年和2014年的8月对南京市区大气中VOCs进行观测，结果表明，VOCs的浓度分别为51.73×10^-9和77.47×10^-9.利用OH消耗速率（L^OH）有效评估VOCs的大气化学反应活性.烯烃和芳香烃是这2年夏季南京市大气VOCs中对L^OH贡献最大的关键活性组分.用FAC法估算南京SOA生成潜势，得到2013和2014年夏季SOA浓度分别为1.95μg/m³和1.01μg/m³；烷烃和芳香烃对SOA的生成潜势分别占4.01%、94.8%和4.46%、94.57%.用PMF模型对南京VOCs进行来源解析，结果表明，2013年夏季南京大气VOCs的最大来源为燃料挥发（22.7%）、其次为天然气和液化石油气泄漏（19.5%）、石油化工业（13.5%）、汽车尾气排放（17.7%）、天然源排放（13.4%）和涂料/溶剂的使用（13.2%），而2014年夏季南京大气VOCs的最大来源为天然气和液化石油气泄漏（35.2%）、其次为石油化工业（20.6%）、不完全燃烧（20.5%）、燃料挥发（15.7%）和汽车尾气排放（8.1%）.

Sources apportionment of volatile organic compounds VOCs in summertime Nanjing and their potential contribution to secondary organic aerosols (SOA)

In this study, VOCs were continuously measured using an online GC system in Nanjing during August 2013 and 2014, with the mean concentrations of 51.73×10^-9 and 77.47×10^-9. The OH radical loss rate (L^OH) method were applied to assess the chemical reactivity of VOCs. The results showed that alkene and aromatics were the key active components, and dominated the L^OH in summertime Nanjing. Fractional aerosol coefficients (FAC) method was used to estimate the formation potentials of secondary organic aerosols (SOA) in Nanjing. The calculated SOA concentrations were 1.95μg/m³ in August of 2013 and 1.01μg/m³ in August of 2014. Aromatics and alkanes contributed about 95% and 4% to the SOA formation. Positive matrix factorization (PMF) model was deployed to identify the sources of VOCs in Nanjing. In the summer of 2013, fossil fuel evaporation was identified as the largest source and accounted for 22.7% of the measured VOCs, followed by natural gas and liquid gasoline (19.5%), petroleum chemical industry (13.5%), vehicle emissions (17.7%), natural sources (13.4%) and paint/solvent usages (13.2%). In 2014, the largest VOCs source was natural gas and liquid gasoline (35.2%), followed by oil and chemical industries (20.6%), incomplete combustion (20.5%), fossil fuel evaporation (15.7%) and vehicle emissions (8.1%).