Decadal increase of organic compounds in winter and spring atmospheric aerosols in East Asia

Monday, 15 December 2014
Shuvashish Kundu1, Kimitaka Kawamura1, Minoru Kobayashi1, Eri Tachibana1, Meehye Lee2 and Jinsang Jung1,3, (1)Hokkaido University, Institute of Low Temperature Science, Sapporo, Japan, (2)Korea University, Department of Earth and Environmental Science, Seoul, South Korea, (3)Korea Research Institute of Standards and Science, Center for Gas Analysis Division of Meteorology for Quality of Life, Daejeon, South Korea
A rapid economic growth in China and other East Asian countries may have changed molecular level organic composition of atmospheric aerosols in East Asia. Molecular level composition is required to better evaluate the roles of organic aersols on climate, air quality and public health. Diacids and oxoacids account for a significant fraction of atmospheric organic matter and their secondary sources are more important than their primary sources. Atmospheric aerosol samples (n = 698) were collected during 2001-2008 at Gosan site in Jeju Island, South Korea. They were analyzed for saturated (C2-C10), unsaturated aliphatic (C4-C5), multifunctional (C3-C7) and aromatic (C8) diacids and oxoacids (C2-C9). According to monthly average concentration, oxalic acid (C2) is the most abundant followed by malonic acid (C3) and succinic acid (C4) in the homologous series of saturated diacids (C2-C10) whereas glyoxylic acid (ωC2) is most abundant in the homologous series of oxoacids (C2-C9). The monthly median, 25th percentile and 75th percentile concentrations of saturated and multifunctional diacids and oxoacids showed the highest in spring (March-May). In contrast, those concentrations for unsaturated aliphatic and aromatic diacids were observed the highest in winter (December-February). The monthly median and percentile (25th and 75th) concentrations of all diacids and oxoacids showed the second peak in the autumn (September-November) while those concentrations were recorded lowest in summer (June-August). A steady increment or decrement was not found in the monthly median and percentile (25th and 75th) concentrations of diacids and oxoacids in any month. However, the curve fitting of those concentrations over the study period shows an incremental trend for major diacids and oxoacids in winter and spring. For example, the monthly median, 25th percentile and 75th percentile concentrations of all major diacids and oxoacids increased up to 3 times from 2001 to 2008 in winter and spring. This study for the first time demonstrates the decadal increase of organic aerosols in East Asia and we discuss the bimodal seasonal variations and incremental trend of organic aerosols based on the annual behavior of ozone, carbon monoxide, and air mass transport pattern in East Asia.