郑州市冬春季大气VOCs污染特征及源解析

Pollution Characteristics and Source Apportionment of Ambient VOCs in Winter and Spring in Zhengzhou

为摸清郑州市冬春季大气挥发性有机物(VOCs)污染特征及来源,对VOCs的浓度变化、SOAP(二次有机气溶胶生成潜势)及来源进行探究。结果表明,郑州冬春季VOCs平均浓度为45.05×10^(-9),其中烷烃20.62×10^(-9),含氧有机物(OVOCs)5.50×10^(-9),炔烃5.27×10^(-9),卤代烃5.15×10^(-9),烯烃5.05×10^(-9),芳香烃3.46×10^(-9);浓度排名前5物种为乙烷8.72×10^(-9)、乙炔5.27×10^(-9)、丙烷4.57×10^(-9)、乙烯3.77×10^(-9)、丙酮3.52×10^(-9)。观测期间上午09时VOCs浓度高于下午14时,VOCs与PM2.5呈明显正相关,冬春季高湿、高温、静稳等天气条件易引起本地VOCs和PM2.5累积和转化。郑州市SOAP为0.74μg/m^3,芳香烃占97.92%,对SOAP贡献较大的前5物种为甲苯、乙苯、间/对二甲苯、苯和邻二甲苯。运用正交矩阵因子(PMF)模型解析出郑州市冬春季VOCs来源为燃煤+生物质燃烧占27.1%、工业溶剂占12.6%、溶剂涂料使用占6.3%、机动车尾气排放占38.2%、燃料挥发占15.8%。建议后期郑州市冬春季重点关注机动车、燃煤及生物质燃烧源排放。

To shed lights on the concentration level, potential of secondary organic aerosol(SOAP) and major sources of at-mospheric volatile organic compounds(VOCs) in winter and spring in Zhengzhou, a sampling campaign has been conducted at different districts. The results showed that the average concentration of VOCs was 45.05 ×10^(-9), of which 20.62 ×10^(-9) for alkanes, 5.50×10^(-9) for OVOCs, 5.27×10^(-9) for alkynes, 5.15×10^(-9) for halocarbons, 5.05×10^(-9) for alkenes and 3.46×10^(-9) for aromatic hydrocarbons. The top five species in concentrations were ethane 8.72 ×10^(-9), acetylene 5.27 ×10^(-9), propane 4.57 ×10^(-9),ethylene 3.77×10^(-9), acetone 3.52×10^(-9), respectively. The mixing ratios of VOCs at 9 am was higher than that at 14 pm during the sampling period, and there was a significant positive correlation between VOCs and PM2.5; stagnant conditions with high humidity, high temperature and low wind speed in winter and spring would favorable for the accumulation of VOCs. In Zhengzhou, concentration of SOAP was 0.74 μg/m^3 and aromatic hydrocarbons contributed 97.92% to the total SOAP. And the top five species that contributed most to SOAP were toluene, ethylbenzene, m/p-xylene, benzene and o-xylene. Positive matrix factor model has been used for source apportionment in this study, and five emission sources, including coal and biomass burning(27.1%), industrial solvents(12.6%), painting and coatings(6.3%), motor vehicle exhaust(38.2%), fuel volatilization(15.8%), has been identified finally. In the future, strict measures aiming at motor vehicles, coal and biomass burning should be executed to reduce emissions of relevant air pollutants during the transitional period from winter to spring in Zhengzhou.