郑州市PM_(2.5)组分、来源及其演变特征

Chemical Components and Sources of PM_(2.5) and Their Evolutive Characteristics in Zhengzhou

为探究郑州市PM_(2.5)主要来源以及季节差异特征,本研究于2019年进行PM_(2.5)周期采样,并分析PM_(2.5)中的无机水溶性离子、碳组分和元素浓度.结果表明,郑州市2019年采样膜样品的PM_(2.5)平均浓度为(67.0±37.2)μg·m^(-3),冬季浓度最高,夏季最低.PM_(2.5)中主要组分依次为:硝酸根、铵根、硫酸根、有机物(OM)、地壳物质和元素碳,春秋季节受地壳物质影响较大,夏季主要受硫酸盐影响,冬季有机物与硝酸盐浓度显著增高.二次转化是硫酸盐和硝酸盐的主要来源,夏季受光化学反应贡献显著,冬季受高湿条件下的液相反应影响明显.NO_(3)^(-)/SO_(4)^(2-)和OC/EC的值表明郑州市PM_(2.5)受汽车尾气排放、煤炭燃烧以及生物质燃烧影响较大.源解析结果表明,2019年二次源贡献最高(49.8%),其中在冬季贡献达到56.5%;一次源中,扬尘在春季(15.2%)和秋季(11.4%)占比略高,机动车源在夏季贡献最大(12.3%),冬季受燃煤源影响较大(13.2%).2014~2019年郑州市PM_(2.5)受二次源影响逐年升高;工业源、生物质燃烧源和燃煤源整体呈下降趋势.

To explore the main sources of PM_(2.5) and the characteristics of seasonal differences in Zhengzhou,PM_(2.5) sampling was conducted in 2019 and the concentrations of inorganic water-soluble ions,carbon components,and various elements were analyzed.Results showed that the average mass concentration of PM_(2.5) in 2019 was(67.0 ± 37.2) μg·m^(-3) with the highest concentration in winter and the lowest in summer.The main components of PM_(2.5) were nitrate,ammonium,sulfate,organic matter,crustal matter,and elemental carbon.In spring and autumn,PM_(2.5) was greatly affected by crustal matter and elemental carbon,and In summer,concentrations were mainly affected by sulfate.In winter,the concentrations of organic matter and nitrate increased significantly,produced by photochemical reactions in summer and aqueous-phase reactions under high humidity in winter.Carbonaceous aerosols were greatly influenced by automobile exhaust emission,coal combustion,and biomass combustion.Source apportionment showed that secondary sources were the greatest contributors in all four seasons,particularly in in winter(56.5%).Among the primary sources,the proportion of dust in spring(15.2%) and autumn(11.4%) was slightly higher,and the contribution of motor vehicle pollution was the largest(12.3%) in summer.In winter,PM_(2.5) was greatly affected by coal combustion(13.2%).From 2014 to 2019,PM_(2.5) in Zhengzhou increased annually under the influence of secondary sources.The contribution of industrial sources,biomass combustion sources,and coal combustion sources exhibited a downward trend over this period.