昆明城区夏季单颗粒气溶胶质谱特征及来源分析

Mass spectra characteristics and source apportionment of single particle aerosols in Kunming during summer

使用单颗粒气溶胶质谱仪(SPAMS)于2015年8月1日至7日,对大气中细颗粒连续监测,有8万多个颗粒具有测径和电离信息,SPAMS所捕获的颗粒数与PM_(2.5)浓度的相关性达到0.78,表明在一定程度上颗粒物数浓度能够反映大气污染变化趋势.分析表明,捕集到的大气颗粒物可分为具有代表性的8类:元素碳(EC)、混合碳(ECOC)、有机碳(OC)、高分子有机碳(HOC)、富钾(K-rich)、矿物质(KWZ)、左旋葡聚糖(LEV)和重金属(Metal)颗粒,不同类型颗粒粒径分布差异较为明显.颗粒类型以ECOC和OC颗粒为主,约占到电离颗粒数的50%以上.ECOC和OC颗粒数百分比在1:00 am至12:00 am左右,先上升后下降;EC颗粒主要受到机动车尾气排放影响,所占比例白天高于夜间;燃烧源排放颗粒物的增加和低风速是造成PM_(2.5)浓度上升阶段的主要原因;源解析结果表明,拓东体育馆周围大气污染源以机动车尾气为主,贡献率为28.5%;其次为燃煤源,贡献率为23.8%.

Single particle aerosol mass spectrometry（SPAMS） was used to analyze the single particle characteristics of aerosols at Tuodong stadium from August 1 to 7,2015. Over 80000 particles were sized and ionized. The correlation（R2） between the SPAMS particle number and PM2.5 concentration was 0. 78,showing that the particle number could reflect the variation trend of atmospheric pollution. The collected atmospheric particulates could be divided into 8 representative groups,including elemental carbon（EC）,mixture of elemental and organic carbon（ECOC）,organic carbon（OC）, high mass organic carbon（HOC）, potassium rich（K-rich）, mineral substance（KWZ）,levoglucosan（LEV） and heavy metal particle. Size distribution of different groups of particles was obviously different. The atmospheric particulates were dominated by ECOC and OC,which accounted for more than 50% of the ionized particles. The particle number of ECOC and OC increased and then decreased from 1 am. to 12 am. Because EC particles were mainly affected byvehicle emissions,the proportion druing the day was higher than that at night. Increase of the particles from combustion source and low wind speed mainly caused the increase of PM2.5 concentration. Moreover,the source apportionment result manifested that vehicle emission was the primary pollution source around Tuodong Stadium,accounting for 28.52%,and the second was coal combustion which contributed 23.79%.