Characteristics and Formation Mechanism of Secondary Organic Aerosol

The formation of secondary organic aerosol(SOA)is one of the research focuses in atmospheric chemical process.In urban atmosphere,secondary organic carbon constitutes about 17%～65%of the total particulate organic carbon.Monoterpene and aromatics are the most important natural and anthropogenic precursors of SOA,respectively.The volatile precursors react with atmospheric oxidants such as hydroxyl(·OH),nitrate radical(NO 3-)and O3 through multiple reaction pathways,producing semi-volatile secondary organics including diacids,multifunctional carbonyls and nitrate organics,etc.Theses compounds can distribute into particulate phase via adsorption and absorption processes,and will alter the property and environmental effects of ambient aerosols.Organic molecular markers are utilized to apportion the sources of atmospheric ambient aerosols,and organic diacids are potential tracers for SOA.In this article,the advances and problems in SOA research are reviewed,and future research recommendations are presented.