HR: 08:45h
AN: A41E-04    [Abstracts]
TI: Ambient Aerosols in the Mexico Megacity Measured by Single Particle Mass Spectrometry
AU: * Moffet, R C
EM: rmoffet@ucsd.edu
AF: UC San Diego, 9500 Gilman Dr, La Jolla, Ca 92093-0314, United States
AU: de Foy, B
EM: foy@eas.slu.edu
AF: Molina Center for Energy and the Environment, 3262 Holiday Ct. Suite 201, La Jolla, CA 92037, United States
AU: de Foy, B
EM: foy@eas.slu.edu
AF: Saint Louis University, 3642 Lindell Blvd, St. Louis, MO 63108, United States
AU: Molina, L T
EM: ltmolina@MIT.EDU
AF: Saint Louis University, 3642 Lindell Blvd, St. Louis, MO 63108, United States
AU: Molina, L T
EM: ltmolina@MIT.EDU
AF: Massachusetts Institute of Technology, 77 massachusetts avenue, Cambridge, MA 02139- 4307, United States
AU: Molina, M J
EM: mjmolina@ucsd.edu
AF: UC San Diego, 9500 Gilman Dr, La Jolla, Ca 92093-0314, United States
AU: Prather, K A
EM: kprather@ucsd.edu
AF: UC San Diego, 9500 Gilman Dr, La Jolla, Ca 92093-0314, United States
AB: Continuous ambient measurements with aerosol time-of-flight mass spectrometry (ATOFMS) were carried out in an industrial/residential section in the northern part of Mexico City as part of the Mexico City Metropolitan Area - 2006 campaign (MCMA-2006) between March 7 and 27, 2006. Major particle types were first characterized by size and chemical composition. Then, using temporal profiles and airmass backtrajectories, the most likely source regions for each of the single particle types was obtained. Industrial particle types were found to be constrained to the northern (industrial) portion of Mexico City, while biomass and OC particles exhibited less directional dependence. Biomass and organic carbon (OC) particle types were found to dominate the accumulation mode. The OC and Biomass particle types were the dominant particle types early in the morning. From the late morning until early evening, the biomass type became the largest contributor to accumulation mode mass. The diurnal pattern can be attributed to either coagulational aging or a change in the air mass. A unique nitrogen-containing organic (NOC) particle type was observed, and is hypothesized to be from industrial emissions based on the temporal profile and back trajectory analysis. Particle mixing states during the MCMA-2006 campaign showed that Oxalate was primarily associated with metals and OC. Based on this observation, we hypothesize that the metals are directly bound to Oxalate, which is known to be a strong metal chelator.
DE: 0305 Aerosols and particles (0345, 4801, 4906)
DE: 0345 Pollution: urban and regional (0305, 0478, 4251)
DE: 0365 Troposphere: composition and chemistry
DE: 5405 Atmospheres (0343, 1060)
SC: Atmospheric Sciences [A]
MN: 2007 Joint Assembly