Single particle diversity and mixing state of carbonaceous aerosols in Guangzhou, China.

Many field studies have investigated the formation mechanisms of organic aerosol (OA) based on bulk analysis, yet the source and formation process of individual organic particles may be quite different due to the diversity of chemical composition and mixing state in single particles. Here we present the observation results of chemical composition and mixing state of carbonaceous single particles at an urban site in Guangzhou. The carbonaceous particles accounted for 74.

Secondary Organic Aerosol Formation from Urban Roadside Air in Hong Kong.

Motor vehicle emissions are an important but poorly constrained source of secondary organic aerosol (SOA). Here, we investigated in situ SOA formation from urban roadside air in Hong Kong during winter time using an oxidation flow reactor (OFR), with equivalent atmospheric oxidation ranging from several hours to several days. The campaign-average mass enhancement of OA, nitrate, sulfate, and ammonium upon OFR aging was 7.

Comparison of daytime and nighttime new particle growth at the HKUST supersite in Hong Kong.

Particles larger than 50-100 nm in diameter have been considered to be effective cloud condensation nuclei (CCN) under typical atmospheric conditions. We studied the growth of newly formed particles (NPs) in the atmosphere and the conditions for these particles to grow beyond 50 nm at a suburban coastal site in Hong Kong. Altogether, 17 new particle formation events each lasting over 1 h were observed in 17 days during 8 Mar-28 Apr and 1 Nov-30 Dec 2011.

Analysis of organic sulfur compounds in atmospheric aerosols at the HKUST supersite in Hong Kong using HR-ToF-AMS.

Organic sulfur compounds have been identified in ambient secondary organic aerosols, but their contribution to organic mass is not well quantified. In this study, using a high-resolution time-of-flight aerosol mass spectrometer (AMS), concentrations of organic sulfur compounds were estimated based on the high-resolution fragmentation patterns of methanesulfonic acid (MSA), and organosulfates (OS), including alkyl, phenyl, and cycloalkyl sulfates, obtained in laboratory experiments. Mass concentrations of MSA and minimum mass concentrations of OS were determined in a field campaign conducted at a coastal site of Hong Kong in September 2011.