Aerosol and Clouds
Chemical characteristics of water-soluble organic carbon in the Asian outflow
Article first published online: 17 NOV 2007
Copyright 2007 by the American Geophysical Union.
Journal of Geophysical Research: Atmospheres (1984–2012)
Volume 112, Issue D22, 27 November 2007
How to Cite
2007), Chemical characteristics of water-soluble organic carbon in the Asian outflow, J. Geophys. Res., 112, D22S30, doi:10.1029/2007JD009116., , , , , , , and (
- Issue published online: 17 NOV 2007
- Article first published online: 17 NOV 2007
- Manuscript Accepted: 19 OCT 2007
- Manuscript Revised: 20 SEP 2007
- Manuscript Received: 2 JUL 2007
- Asian outflow;
 Semicontinuous measurements of water-soluble organic carbon (WSOC) and organic carbon (OC) in PM2.5 were made at Gosan, Korea, in March-April 2005. On average, the WSOC/OC mass ratio for all air masses observed at Gosan was 0.30 ± 0.12. WSOC correlated well with CO (r2 = 0.54) in Chinese outflow, suggesting that a major part of the observed WSOC and/or their precursors was of combustion origin. The relationship between the increase of WSOC and O3 suggests that the observed WSOC was mostly secondary product. To interpret the measured organic compounds, thermal analyses of organic standards were made in the laboratory. Thermograms of a single standard of water-soluble organic species showed that carbon that evolved at high temperatures (600°–870°C) was generally associated with water-soluble compounds having high molecular weights (MWs) on the order of hundreds, while carbon that evolved at low temperatures (<300°C) generally had MWs of less than ∼180 g mol−1. Positive matrix factorization (PMF) analysis revealed three organic compound groups (low, medium, and highly refractory compounds) based on the OC thermograms. On average, highly and low refractory compound groups accounted for 79% and 21% of the WSOC mass, respectively, at Gosan. Highly refractory compound groups significantly contributed to WSOC regardless of air mass origin. The results of the laboratory experiments imply that a large fraction of these highly refractory compound groups was likely associated with high MW compounds. For water-insoluble organic carbon(=OC–WSOC), medium and low refractory compound groups accounted for 60% and 40%, respectively, consistent with the results of the laboratory experiments.