郑州市某城区冬季不同污染水平大气VOCs特征及源解析

于2019年1月3～23日,在郑州市某城市站点对挥发性有机物(VOCs)进行观测,研究不同污染水平下VOCs组成、变化特征、来源及其对二次有机气溶胶(SOA)生成的影响.结果表明,观测期间含氧VOCs和烷烃为VOCs的主要组分,乙酸乙酯和丙酮为最丰富的物种.清洁天演变至重度污染过程中,VOCs体积分数增高约1倍,大部分物种体积分数随污染程度加重而增高.基于正交矩阵因子模型(PMF),观测期间VOCs主要来源于机动车排放、工业排放、燃烧源、溶剂使用和液化石油气(LPG)使用,且不同污染水平下来源贡献差异明显,重污染期间工业排放和溶剂使用的源贡献分别增高至约清洁天的9倍和3倍.芳香烃为SOA生成潜势(SOA_p)贡献最大的组分,甲苯和间/对-二甲苯为贡献最大的物种,溶剂使用源为贡献最大的来源,重度污染期间总SOA_p增大至约清洁天的2.6倍.加强管控芳香烃类化合物及溶剂使用等相关源的排放对改善郑州市冬季霾污染具有重要意义.

Characteristics and Source Apportionment of VOCs at Different Pollution Levels During the Winter in an Urban Area in Zhengzhou

In this study, volatile organic compound (VOC) species were measured at an urban site in Zhengzhou from January 3 to 23, 2019, to investigate the composition, variation characteristics, sources, and effects on secondary organic aerosol (SOA) formation of VOCs at different pollution levels. Results showed that oxygenated VOCs and alkanes were the main components of VOCs, while ethyl acetate and acetone were the most abundant species. During the process from clean days to heavy pollution days, the mixing ratio of VOCs approximately doubled, and the mixing ratios of most species continued to increase as the pollution level increased. Based on the positive matrix factorization (PMF) model, during the observation period, VOCs mainly originated from vehicle emissions, industrial emissions, combustion sources, solvent utilization, and liquefied petroleum gas (LPG) utilization. There were significant differences in the source contribution at different pollution levels, and the contributions of industrial emissions and solvent utilization during the heavy pollution days increased to 9 times and 3 times that of the clean days, respectively. With respect to the SOA formation potential (SOA_p), aromatics were the component that contributed the most, and toluene and m/p-xylene were the species that contributed the most, while solvent utilization was the greatest source contributor. During the heavy pollution period, the total SOA_p increased to approximately 2.6 times that of clean days. There is a great need to reduce winter haze pollution in Zhengzhou by strengthening the control of aromatic emissions and related sources such as solvent utilization.