The aerosol size distribution is important to understand its sources, secondary formation and removal processes and also to access the effects on atmospheric visibility. From 2007 to 2009, aerosol samples were collected at four urban, rural and elevation sites in Beijing, Jinan and Mt. Heng in China via a micro-orifice uniform deposit impactor, followed by subsequent chemical analysis in laboratory. Generally, the sulfate, ammonium and potassium ions mostly appeared in fine particles, and the concentration peaks primarily appeared in the droplet mode (0.56~1.8 �m). The nitrate, sodium and chlorides ions existed both in fine and coarse particles, with concentration peaks appearing in size ranges of 0.56~1.8 �m and 3.2~5.6 �m, respectively. The organic carbons, formic acid and acetic acid were evenly produced in fine and coarse particles. The element carbons, oxalic acid and methaesulfonic acid mostly existed in fine particles. The above characteristics of size distributions of aerosol components indicates vast influences of anthropogenic emissions and atmospheric physicochemical processes on atmospheric aerosols in the study region. Fine particles, particularly the droplet- mode aerosols, contributed a very large fraction to the light extinction coefficient. The droplet mode aerosol concentration showed strong negative correlation with the atmospheric visibility. The high concentrations of sulfates and nitrates in the droplet mode were the most important pollutants to lead an increase in light extinction coefficient and the occurrence of haze pollution. In urban Jinan where highest aerosol mass concentration was observed, the liquid water content in aerosols was the key factor to govern the heterogeneous aqueous reactions on aerosol surfaces. High humidity in haze episode was favorable for fast production of sulfates and nitrates in the droplet mode.

Characteristics and implications of aerosol mass size distributions in typical cities and mountain in China

247th National Meeting (2014)

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