南京工业区秋季大气挥发性有机物污染特征及来源解析

Characteristics and Source Apportionment of Atmospheric VOCs in the Nanjing Industrial Area in Autumn

2018年秋季在南京利用大气挥发性有机物(volatile organic compounds,VOCs)吸附浓缩在线监测系统(AC-GCMS 1000)对大气VOCs进行连续观测,以了解其化学特征、臭氧生成潜势和污染来源.结果表明,南京秋季大气VOCs体积分数为(64.3±45.6)×10^-9,以烷烃(33.1%)、含氧挥发性有机物(OVOCs)(22.3%)及卤代烃(21.8%)为主.VOCs的昼夜变化呈"双峰型"变化特征,高值主要出现在清晨的06:00~07:00及夜间的18:00~20:00,主要受机动车排放及气象要素的共同影响.秋季南京VOCs的臭氧生成潜势(ozone formation potential,OFP)为267.1μg·m^-3,主要贡献物种是芳香烃类化合物(55.2%)和烯烃类化合物(20.8%).PMF受体模型源解析确定5个VOCs来源,分别是交通排放(34%)、工业排放(19%)、LPG排放(17%)、涂料及有机溶剂挥发(16%)以及生物质燃烧和燃煤排放(14%),因此控制南京工业区秋季大气污染应主要着力于交通及工业排放的治理.

Atmospheric volatile organic compounds(VOCs)were continuously monitored via an online GC-FID/MS system in Nanjing during the autumn of 2018 to analyze the chemical characteristics,ozone formation potential(OFP),and potential sources of VOCs in this industrial region.During the sampling period,the average concentration of atmospheric total VOCs(TVOCs)was(64.3±45.6)×10^-9.Alkanes were the most predominant VOC compound,accounting for 33.1%of the TVOC mass,followed by oxygenated volatile organic compounds(OVOCs,22.3%)and halogenated hydrocarbons(21.8%).The diurnal cycles of VOCs revealed"bimodal"distributions.The higher concentrations of VOCs observed at 06:00-07:00 and 18:00-20:00 were attributed to the intense traffic emissions and meteorological conditions.Furthermore,maximum incremental reaction(MIR)analysis was used to estimate OFP of VOCs.The results showed that the calculated OFP in Nanjing was 267.1μg·m^-3.Aromatic hydrocarbons and alkenes were the dominant contributors to OFPs,which accounted for 55.2%and 20.8%to the total OFPs,respectively.Finally,five potential sources of VOCs were quantified by the positive matrix factorization model,including traffic emissions(34%),industrial emissions(19%),liquefied petroleum gas(LPG)emissions(17%),usage of paints and solvents(16%),coal combustion,and biomass burning(14%).These findings suggested that control of vehicle emissions and industrial sources would be an important way to reduce VOC concentrations and improve air quality in Nanjing.