Aging of Secondary Organic Aerosol in Laboratory Chambers

CHRISTINE L. LOZA (1), Puneet S. Chhabra (1), Lindsay D. Yee (1), Man Nin Chan (1), Arthur W.H. Chan (1), Paul O. Wennberg (1), Richard C. Flagan (1), John H. Seinfeld (1)

(1) California Institute of Technology, Pasadena

     Abstract Number: 192
     Last modified: April 28, 2010

Abstract
Conventional laboratory experiments designed to study secondary organic aerosol formation from hydrocarbon precursors generally do not exceed a duration of about 1 day; this is to be contrasted with atmospheric lifetimes of 5-12 days, during which there is ample evidence that ambient particles undergo additional oxidative processes not accessible in current chamber experiments. In order to identify mechanisms involved in ambient aerosol aging, we report the results of experiments performed in the Caltech laboratory chambers in which hydrocarbon-aerosol systems were subjected to multi-day ambient OH exposure. The evolution of both gas- and aerosol-phase species was measured to determine chemical and physical characteristics of aging processes. O:C and H:C ratios were determined by high resolution AMS measurements to compare the aged aerosol generated to field aerosol measurements.