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
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摘要: 为研究煤化工产业园区VOCs污染特征及其对大气细颗粒物(PM2.5)和臭氧(O3)的贡献,该研究于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种挥发性有机物(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O3和PM2.5二次组分(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±50.57)×10-9,显著高于该园区所在城市的城区站点VOCs浓度. ②含氧VOCs(OVOCs)是该园区VOCs的主要特征污染物,占总VOCs浓度的32.6%,乙醇、丙醛和甲醛是浓度前三的物种. ③VOCs的臭氧生成潜势(OFP)为595.64 μg/m3. 各组分对O3贡献潜势的大小依次为:OVOCs>烯烃>芳香烃>烷烃>卤代烃>含硫VOC>炔烃. OFP前十物种均为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%. ④1,2,3-三甲苯、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1,2,3-三甲苯的SOAFP最大,占总SOAFP的55.7%,主导了SOA生成. 研究显示,煤化工产业园区中丙醛、甲醛等OVOCs及1,2,3-三甲苯、间/对-二甲苯等芳香烃对大气复合污染贡献较大,是开展PM2.5和O3协同控制重点关注的物种.Abstract: To study the characteristics of volatile organic compounds (VOCs) and their contribution to atmospheric fine particulate matter (PM2.5) and ozone (O3), the measurements of 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 O3 and secondary organic aerosols (SOA) were analyzed. The results were shown as followed: ①The total mixing ratio of VOCs was (89.21±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. ②Oxygenated VOCs (OVOCs) were the most abundant VOCs, accounting for 32.6% of the total VOCs. Ethanol, propionaldehyde and formaldehyde were the top three OVOCs species. ③The total ozone formation potential (OFP) of VOCs was 595.64 μg/m3. 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%). ④The top VOCs contributing to SOA formation potential (SOAFP) were 1,2,3-trimethylbenzene, m/p-xylene, o-xylene and ethylbenzene , of which 1,2,3-trimethylbenzene contributed the most (55.7%). Overall, OVOCs and aromatic hydrocarbons (propionaldehyde, formaldehyde, 1,2,3-trimethyl benzene and m/p-xylene) in coal chemical industrial park contribute significantly to the complex air pollution, and should be the key species to carry out the joint control of PM2.5 and O3.
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