Special session of California 2000 field study - Air Pollution Modeling and Its Application - page 543

4. Conclusions
The quantity and origin of SOA formation in the SJV between December 15, 2000
and January 7, 2001 were predicted using a state of the science SOA formation
mechanism. While the majority of predicted OA in the SJV during the winter
episode was of primary origin, SOA concentrations were not negligible. Averaged
over December 25, 2000 to January 7, 2001, the dominant sources of SOA in the
SJV were solvent use (28%), catalyst-gasoline engines (25%), wood smoke (16%),
non-catalyst gasoline engines (13%), and other anthropogenic sources (11%).
Acknowledgments We would like to thank Robert Griffin for helpful comments. This research
was supported by the California Air Resources Board and the San Joaquin Valleywide Air
Pollution Study Agency under contract 2000-05PM. The statements, opinions, findings, and
conclusions of this paper are those of the authors and do not necessarily represent the views of
the California Air Resources Board.
References
Chow JC, Chen LWA, Watson JG et al. (2006) P M 2.5 chemical composition and spatiotemporal
variability during the California Regional PM 10 /PM 2.5 Air Quality Study (CRPAQS). Journal
of Geophysical Research. doi:10.1029/2005JD006457
Kleeman MJ, Ying Q, Lu J et al. (2007) Source apportionment of secondary organic aerosol
during a severe photochemical smog episode. Atmospheric Environment 41: 576-591.
Kleeman MJ, Riddle SG, Robert MA et al. (2009) Source apportionment of fine (PM 1.8 ) and
ultrafine (PM 0.1 ) airborne particulate matter during a severe winter pollution episode.
Environmental Science & Technology 43: 272-279.
Kroll JH, Seinfeld JH (2008) Chemistry of secondary organic aerosol: Formation and evolution
of low-volatility organic in the atmosphere. Atmospheric Environment 42: 3593-3624.
5. Questions and Answers
Question: Saffett Tanrikulu at Bay Area Air Quality Management District stated
that the SJV acts as a source of nitrate aerosol to the Bay Area. He stated that
the highest concentrations in the SJV and the Bay Area occur during periods of
northward flow.
Answer: These trends were not evident in the current episode. Each region pro-
duces most of its own nitrate and we were confident in our model results.
Question: Ron Cohen from UC, Berkeley asked if any of the unknown OC at
Angiola could be related to agricultural sources.
Answer: This was certainly a possibility. However, we also had unknown sources
of NOx and elemental carbon at Angiola that suggested an anthropogenic
influence.