Characteristics of individual particles in the atmosphere of Guangzhou by single particle mass spectrometry

Continuous ambient measurement of atmospheric aerosols was performed with a single particle aerosol mass spectrometer (SPAMS) in Guangzhou during summer of 2012. The aerosols mainly consisted of carbonaceous particles as major compositions in submicrometer range, including K-rich (29.8%), internally mixed organics and elemental carbon (ECOC, 13.5%), organic carbon-rich (OC, 18.5%), elemental carbon (EC, 12.3%) and high molecular OC (HMOC, 3.2%), and inorganic types (e.g., Na-rich Na-K, Fe-rich, V-rich, and Cu-rich) as major ones in supermicrometer range. Results show that carbonaceous particles were commonly internally mixed with sulfate and nitrate through atmospheric processing, in particular, with sulfate; inorganic types were dominantly internally mixed with nitrate rather than sulfate, indicative of different evolution processes for carbonaceous and inorganic particles in the atmosphere. It was observed that variations of these particle types were significantly influenced by air mass back trajectories (BTs). Under the influence of continental BTs, carbonaceous types were prevalent, while Na-K and Na-rich types considerably increased when the BTs originated from south marine regions. Number fraction of carbonaceous types exhibited obvious diurnal variation throughout the sampling period, which reflects their relatively stable emission and atmospheric processes. Two EC particle types LC-EC and NaK-EC showed different diurnal distributions, suggesting their different origins. The obtained information on the mixing state and the temporal variation of particle types is essential for developing an understanding on the origin and evolution processes of atmospheric aerosols.