运用单颗粒气溶胶质谱技术表征广州市大气含铅颗粒的污染特征

摘要

A single particle aerosol mass spectrometer was used to characterize the particle types,mixing state,and sources of lead-containing particles in different seasons in Guangzhou,China.The results showed that the seasonal average number fraction of lead-containing particles followed the order summer (3.6％) ＞ fall (2.4％) ＞ winter (1.8％) ＞ spring (1.0％).The lead-containing particles were classified as K-Pb,EC-Pb,Pb-rich,Metal-Pb,and Dust-Pb,which may have originated from coal combustion,steel and metal smelting,and dust.The different types of lead-containing particles had distinct mixing states with secondary species,such as sulfate and nitrate.Pb-rich and Dust-Pb particles were mainly mixed with nitrate,while the other three types were mixed with both sulfate and nitrate.The main type was K-Pb,which accounted for ＞ 50％ of the lead-containing particles,followed by Pb-rich (～15％) and Metal-Pb (5％～10％) in all four seasons.Notably,the contribution of EC-Pb was much higher in spring than in the other seasons.Dust-Pb was only detected in winter due to long-range transport of air carrying dust particles from northern China.A Pb contamination event was observed during which the daily number fraction of lead-containing particles approached 14％.This event could be explained by particle transport from steel and metal smelter emissions in northern and northeastern Guangzhou.This study provides a reference for the assessment of the effects of atmospheric lead on the ecological environment and human health.%运用单颗粒气溶胶质谱仪研究了广州市不同季节大气中含铅颗粒的类型、混合状态和来源.结果表明,广州市大气含铅颗粒不同季节的占比分别为:3.6％(夏季)、2.4％(冬季)、1.8％(秋季)、1.0％(春季).基于质谱特征,将含铅颗粒分为K-Pb、EC-Pb、Pb-rich、Metal-Pb和Dust-Pb五种类型,主要来源是燃煤、钢铁和金属冶炼厂以及沙尘.不同类别颗粒物与二次气溶胶的混合状态不同.Pb-rich和Dust-Pb主要与硝酸盐混合,而其余三类与硫酸盐和硝酸盐均有混合.四个季节中含铅颗粒都是K-Pb占比最大(超过50％),其次是Pb-rich(约15％)和Metal-Pb(5％～10％).比较特别的是EC类型在春季的比重远高于其余季节.在冬季存在含量较低的Dust类型,主要受携带沙尘的中国北部气流的影响.采样期间发生过一次含铅颗粒的污染事件(日均占比最高达14％),主要是受来自广州北部和东北部的钢铁和金属冶炼厂排放的铅颗粒影响.本研究为评估大气中含铅颗粒的生态健康效应提供了参考依据.