京津冀区域气溶胶中无机水溶性离子污染特征分析

Characteristics of Inorganic Water-soluble Ions from Aerosols in Beijing-Tianjin-Hebei Area

在北京、天津、石家庄、承德城区和北京上甸子区域本底站共设置5个采样点,2009～2010年分季节采集环境PM2.5,并分析其中的无机水溶性离子,进而研究京津冀区域气溶胶中离子组分的污染特征.研究表明,京津冀PM2.5污染较重,北京、天津和石家庄年均浓度均超过了100μg/m3;5个站点二次离子(SO42-、NO 3-、NH 4+)总年均浓度为22～75μg/m3,二次离子春夏两季浓度较高,且夏季SO24-浓度水平远远高于NO 3-.反映地壳组分的Mg2+和Ca2+春季浓度较高,其中天津和石家庄2个城市地壳组分的污染相对较重;北京市区PM2.5和二次离子污染特征与2004前相比有较大变化,PM2.5浓度四季较稳定,二次离子夏季明显高于其它季节,NO 3-/SO24-比值较以往明显升高;上甸子PM2.5和二次离子污染受到北京城区的影响较大.

PM2.5 samples were collected at five sites in BTH（Beijing Tianjin and Hebei） area（four urban sites of Beijing,Tianjin,Shijiazhuang,Chengde,and one site of Shangdianzi background station） from 2009 to 2010.The inorganic water-soluble ions were analyzed and spatio-temporal characteristics of ions were concluded.The concentrations of PM2.5 were quite high,with annual average more than 100μg/m3 in Beijing,Tianjin and Shijiazhuang.The annual average concentrations of secondary ions（SO2-4,NO-3,NH＋4） were 22-75 μg/m3 at five sites,and higher in the spring and summer.In BTH,SO2-4 concentrations were much higher than NO-3 in the summer,and Mg2＋ and Ca2＋ were higher in the spring.Mg2＋ and Ca2＋ were much higher in Tianjin and Shijiazhuang,reflecting more crust materials pollution.The characteristics of PM2.5 and water-soluble ions for Beijing in this paper were very different from the similar studies before 2004,showing more stable PM2.5 concentrations in four seasons,higher secondary ions in summer,and higher NO-3/SO2-4 than before.The results of Shangdianzi background station（SDZ） also showed that the aerosol pollution of SDZ was largely influenced by Beijing urban area.