Organic acids including monocarboxylic acids, dicarboxylic acids and aromatic acids in atmospheric aerosols have been studied owing to their potential roles in affecting the global climate. These acids can reduce the surface tension of particles to form cloud condensation nuclei and are involved in a series of atmospheric chemical reactions occurring in the gas, water and particle phases. As influenced by urbanization and industrialization, air pollution has been becoming more and more severe in PRD, which is one of the four heaviest haze regions in China, together with the Yangtze River Delta, Beijing-Tianjin-Tangshan and Chongqing. The seasonal and spatial variations of organic acids were not studied. To better understand the organic compositions in the PRD region, PM_2.5 samples were acquired at four sampling sites(Guangzhou, Zhaoqing, The Hong Kong Polytechnic University and Hok Tsui) simultaneously during winter and summer. Through careful analysis, they have gotten the spatial and seasonal variations of selected organic species and to explore their implications for sources and photochemical reactions.

The paper has been published in Atmospheric Chemistry and Physics recently.

K. F. Ho et al., Summer and winter variations of dicarboxylic acids, fatty acids and benzoic acid in PM_2.5 in Pearl Delta River Region, China, Atmospheric Chemistry and Physics 11 (2011) 2197-2208