减排管控期厦门市大气中挥发性有机物浓度变化特征及来源分析

Characteristics and Source Apportionment of Atmospheric Volatile Organic Compounds During Emission Control Period in Xiamen

为研究大气减排管控措施对厦门市大气中挥发性有机物(Volatile organic compounds,VOCs)浓度及来源的影响,评估VOCs减排效果,于2017年8月28日至9月13日在厦门市中国科学院城市环境研究所(郊区站)使用VOCs在线监测仪器(AC-GCMS 1000)对金砖会议期间及前后厦门市大气挥发性有机物进行监测和分析。结果表明,金砖会议前、中、后时间段的总挥发性有机物(TVOCs)体积浓度分别为(19.09±9.65)×10^(-9)(V/V)、(9.39±3.35)×10^(-9)(V/V)和(14.88±9.68)×10^(-9)(V/V)。会议期间TVOCs较会议前分别下降51%和37%,其中含氧挥发性有机物(OVOCs)下降比例为90%,芳香烃与烯烃分别下降53%和38%,这3类VOCs均下降超过30%。会议前、中、后时间段总臭氧生成潜势(OFP)分别为162.06、77.14和121.45μg/m^3,二次有机气溶胶生成潜势(SOAP)分别为2.14、1.65和1.93 ng/m^3,会议期间OFP与SOAP较会议前分别下降52%和23%,芳香烃和烯烃为生成OFP的关键物种,芳香烃对SOA的生成起主导作用。PMF模型共解析出5个污染源,分别为机动车尾气源、植物排放源、溶剂使用源、油品挥发源和背景源,溶剂使用源为整个监测期间VOCs最大贡献源(32%),其质量浓度较会议前下降76%。本研究结果表明,控制溶剂使用源和机动车尾气排放源,会显著降低主要VOCs物种的浓度,对后续控制O_3生成及潜在SOA的产量有显著效果。本研究为厦门市及其它地区的VOCs污染控制提供了合理有效的参考。

To investigate the characteristics and source apportionment of volatile organic compounds(VOCs) during the BRICS Conference in Xiamen and evaluate the effects of source control and mitigation policies, a online monitoring instrument(AC-GCMS 1000) was used to monitor VOCs, from August 28, 2017 to September 13 in the institute of Xiamen City, Chinese Academy of Sciences. The results showed that the concentrations of total volatile organic compounds(TVOCs) were(19.09±9.65)×10-9(V/V),(9.39±3.35)×10-9(V/V),(14.88±9.68)×10-9(V/V) before, during and after the conference, respectively. During the BRICS Conference, TVOCs decreased by 51% and 37% compared with that of before and after the conference. Specifically, the oxygen volatile organic compounds(OVOCs), aromatics and alkenes, were decreased by 90%, 53% and 38% respectively. The ozone formation potential(OFP) was the highest before the conference(162.06 μg/m3), followed by that after(121.45 μg/m3) and during(77.14 μg/m3) conference. The same pattern was identified for the secondary organic aerosols potential(SOAP), which was calculated as 2.14, 1.65 and 1.93 mg/m3, respectively. Overall, both OFP and SOAP were decreased by 52% and 23%, respectively. Aromatics and Alkenes were the key contributors of OFP. Aromatics played a leading role in the formation of SOA. Five emission sources of VOCs were identified by PMF model, including vehicle exhaust, biogenic VOCs, solvent utilization, gasoline evaporation and the background VOCs. The solvent utilization source was the largest contributor of VOCs during the Xiamen BRICS Conference(32%), which was decreased by 76% compared with that before the conference. The results of this study show that the mitigation of solvent utilization and vehicle exhaust can significantly reduce the concentrations of major VOCs species, and have a great effect on the subsequent control of O3 and SOA production. This work suggests an effective direction to control VOCs emission in Xiamen and other areas.