运用单颗粒气溶胶质谱技术初步研究广州大气矿尘污染

自主研发的单颗粒气溶胶飞行时间质谱仪(Single Particle Aerosol Mass Spectrometer,SPAMS)采用空气动力学透镜、双激光测径系统以及双极飞行时间质量分析器,并用其对广州市大气细颗粒物进行在线分析,实现了矿尘颗粒物的空气动力学直径和化学组成的同时检测.在连续4 d的采样中,共采集到249 057个粒径在0.2～1.2μm且同时含有正负质谱信息的颗粒物,其中矿尘颗粒物占7.9%.结果表明:矿尘颗粒物的正离子成分以Ca2+,K+,Fe2+和Na+为主,同时还含有Li+,Mg2+,V5+,Ba2+和Ti4+等;负离子成分以NO3-和NO2-为主,另外还含有HSO4-,SiO3-和PO3-等.在广州市大气细颗粒物中,矿尘贡献不如含碳颗粒物和生物质燃烧颗粒物,且在矿尘颗粒物中贡献较大的几类(如含钙、含铁、含钠钾颗粒物等)大多是老化的成分.

Preliminary Study of Mineral Dust Particle Pollution Using a Single Particle Aerosol Mass Spectrometer (SPAMS) in Guangzhou

An independent R&D single particle aerosol mass spectrometer(SPAMS),which is mainly composed of an aerodynamic lens,a two-laser beam system and a bipolar time-of-flight mass analyzer,was used for on-line analysis of fine particles in Guangzhou,China.The aerodynamic diameter and chemical composition of the mineral dust aerosol particles were measured simultaneously by the SPAMS.During four days of consecutive days sampling,249 057 particles with diameter between 0.2-1.2 μm in both the positive and negative spectra were detected,in which mineral dust particles accounted for 7.9%.The results showed that for these mineral dust particles,the positive composition ions were mainly Ca2+,K+,Fe2+ and Na+,and that Li+,Mg2+,V5+,Ba2+ and Ti4+ also sometimes appeared.The negative composition ions were mainly NO3-and NO2-,as well as HSO4-,SiO3-,PO3-and others.At the same time,it was observed that the contributions of carbonaceous particles and particles from biomass burning were larger than the contribution from mineral dust particles for fine particles in Guangzhou,and most of mineral dust particles(such as Ca-rich,Fe-rich,NaK-rich) were aged ingredients.