ALBERT

Description: [1]  Pollutants during haze and Asian dust storms are transported out of the Asian continent, affecting the regional climate and the hydrological and biogeochemical cycles. Understanding the physical and chemical properties of such aerosol particles is essential to quantify their impacts. In order to determine physical and chemical properties of aerosol particles before leaving the Asian continent, we carried out a field campaign from 14 April to 2 May, 2011 at a background site in the path of Asian dust and haze outflows. We measured concentrations of gaseous pollutants (SO 2 , NO 2 , NO, O 3 , and CO), black carbon (BC), and particle number in-situ and collected airborne particles for microscopic analysis. Pollutant concentrations (BC, 4 µg m -3 ; CO, 808 ppb; SO 2 , 24 ppb; NO 2 , 37 ppb) were highest during haze periods, except for the PM 2.5 mass, which was highest (162 µg m -3 ) during a dust storm. 71% of haze particles were coated with organic films and 32% were internal mixtures of sulfates and refractory fine particles (e.g., soot, metal/fly ash, and mineral particles). 79% of the haze particles have a deliquescence relative humidity at 68-70%. During a dust storm, soot particles were observed among dust particles. Most dust particles were hydrophobic and no Ca(NO 3 ) 2 was observed in dust particles collected during the dust storms but up to 32% of dust particles were found to be coated with Ca(NO 3 ) 2 after the main dust storm moved out of the sampling area. These results indicated that both natural and anthropogenic aerosol particles in Asian outflow can undergo significant physical and chemical processes before leaving the Asian continent.