中国典型背景站夏季VOCs污染特征及来源解析

选取庞泉沟、神农架、武夷山和长岛4个代表性大气背景站，使用SUMMA罐采样及GC-FID/MS方法分析了4个背景站夏季环境空气中57种挥发性有机污染物浓度水平、物种组成以及日变化特征，并利用PMF模型对背景站VOCs进行来源解析和臭氧生成潜势（OFP）分析.结果表明，采样期间庞泉沟、神农架、武夷山和长岛的VOCs平均浓度分别为（23.06±8.14）×10^-9，（8.25±4.27）×10^-9，（7.95±11.31）×10^-9和（11.98±8.80）×10^-9.除庞泉沟外，背景点烷烃、芳香烃、烯烃和炔烃浓度均明显低于城市地区.背景点烷烃、芳香烃、烯烃占比与城市地区差异不显著，但背景点炔烃占比显著小于城市地区.烷烃和芳香烃的日变化呈现出白天消减，夜间累积的特点，烯烃浓度则在09：00~15：00点出现峰值.PMF源解析及成分分析结果表明，人为排放源对背景站VOCs构成和臭氧生成潜势有重要贡献.汽油挥发、溶剂及涂料使用、机动车尾气等排放源对4个背景站点的VOCs浓度贡献占比在39%~58%之间，对OFP贡献占比在35%~58%之间.燃烧源对4个背景站点的VOCs浓度贡献占比在18%~21%之间，对OFP贡献占比在约为13%..植物源对4个背景站点的VOCs浓度贡献占比在7%~17%之间，对OFP贡献占比在8%~33%之间，植物源贡献占比高于城市地区.

The characteristics and source apportionments of VOCs at typical background sites during summer in China

57 volatile organic pollutants at four representative background stations, namely, Pangquangou, Shennongjia, Wuyishan and Changdao in China, were collected using SUMMA Canisters and analyzed by GC-FID/MS methods during summer of 2019. Concentration, composition and diurnal variation characteristics of VOCs were discussed and the PMF model was used to identify the source of VOCs and its ozone formation potential (OFP). The results showed that the averaged VOCs concentration at Pangquangou, Shennongjia, Wuyishan and Changdao background sites were (23.06±8.14)×10^-9, (8.25±4.27)×10^-9, (7.95±11.31)×10^-9 and (11.98±8.80)×10^-9, respectively. The concentrations of alkane, aromatics, alkenes and alkynes at all background sites but Pangquangou were significantly lower than that in urban sites. The respective proportions of alkane, aromatics, alkenes in background sites were similar with that in urban sites, while the proportions of alkynes at background sites were significantly lower than that in urban sites. The diurnal variations of alkane and aromatics at background sites showed a pattern of declining in the day and accumulating at night, while alkenes reach its peak concentration at 09:00~15:00. Source apportionments by PMF model and components analysis showed that the VOCs concentrations and OFP at four background sites were affected significantly by anthropogenic sources. The contribution from sources of gasoline and organic solvents evaporation, usage of coating material and automobile exhaust at four background sites ranged from 39% to 58% of VOCs and 35% to 58% of OFP. Besides, the sources related to fuel combustions contributed 18% to 21% of VOCs and 13% of OFP, respectively. Sources from plant emission processes contributed 7% to 17% of VOCs and 8% to 33% of OFP at 4 background sites, which were higher than that at urban sites.