煤化工产业园区挥发性有机物污染特征及其对大气复合污染的贡献

Characterization of Ambient VOCs in a Coal Chemical Industry Park and Their Contribution to Complex Air Pollution

为研究煤化工产业园区挥发性有机物(VOCs)污染特征及其对大气细颗粒物(PM_(2.5))和臭氧(O_(3))的贡献,本研究于2021年夏季利用气相色谱/质谱联用仪在某大型煤化工产业园区开展了环境空气115种VOCs的在线监测研究,分析了VOCs的浓度水平、组成特征、日变化特征、潜在来源及其对O_(3)和PM_(2.5)中二次有机气溶胶(SOA)的生成贡献.结果表明:(1)观测期间,园区站点VOCs的平均体积分数为89.32×10^(-9)±50.57×10^(-9),显著高于该园区所在城市的城区站点VOCs浓度水平.(2)含氧VOCs(OVOCs)是该园区VOCs的主要特征污染物,占总VOCs体积分数的48.2%,乙醇、丙醛和甲醛是体积分数排名前三的物种.(3)VOCs的臭氧生成潜势(OFP)为595.64μg/m^(3),各组分对O_(3)贡献潜势的大小表现为OVOCs>烯烃>芳香烃>烷烃>卤代烃>含硫VOC>炔烃.OFP排名前十的物种均为OVOCs、烯烃和芳香烃,其中丙醛对OFP的贡献占比最高,占总OFP的22.2%.(4)间/对-二甲苯、邻二甲苯和乙苯等苯系物对二次有机气溶胶生成潜势(SOAFP)的贡献突出,其中间/对-二甲苯的SOAFP最大,占总SOAFP的29.6%,主导了SOA生成.研究显示,煤化工产业园区中丙醛和甲醛等OVOCs、顺-2-丁烯等烯烃以及间/对-二甲苯与邻二甲苯等芳香烃对大气复合污染贡献较大,是开展PM_(2.5)和O_(3)污染协同控制重点关注的物种.

In order to study the characteristics of volatile organic compounds(VOCs)and their contribution to atmospheric fine particulate matter(PM_(2.5))and ozone(O_(3)),the measurements of 115 VOCs in the atmosphere were conducted by a gas chromatography coupled with a mass spectrometry in a large coal chemical industrial park during the summer of 2021.The levels,composition characteristics,diurnal variation,potential sources of VOCs,and their contributions to the formation of O_(3)and secondary organic aerosols(SOA)were analyzed.The results were shown as followed:(1)The total mixing ratio of VOCs was 89.32×10^(-9)±50.57×10^(-9)in the coal chemical industrial park during the observed period,which was significantly higher than that detected at the urban site in the city where the coal chemical industrial park was located.(2)Oxygenated VOCs(OVOCs)were the most abundant VOCs,accounting for 48.2%of the total mixing ratio of VOCs.Ethanol,propionaldehyde and formaldehyde were the top three OVOCs species.(3)The total ozone formation potential(OFP)of VOCs was 595.64μg/m^(3).The contributions of VOCs to OFP were OVOCs>alkenes>aromatics>alkanes>halogenated hydrocarbons>sulphur-containing VOC>alkyne.The top ten VOCs species contributing to OFP were OVOCs,alkenes and aromatics,of which propionaldehyde contributed the most(22.2%).(4)The top VOCs contributing to SOA formation potential(SOAFP)were m/p-xylene,o-xylene and ethylbenzene,of which m/p-xylene contributed the most(29.6%).Overall,OVOCs such as propionaldehyde and formaldehyde,alkenes such as cis-2-butene,and aromatics such as m/p-xylene and o-xylene contribute significant to the complex air pollution in the coal chemical industrial park,and are the VOCs species of key concern for carrying out PM_(2.5)and O_(3)synergistic control.