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- Title
On the volatility and production mechanisms of newly formed nitrate and water soluble organic aerosol in Mexico City.
- Authors
Hennigan, C. J.; Sullivan, A. P.; Fountoukis, C. I.; Nenes, A.; Hecobian, A.; Vargas, O.; Peltier, R. E.; Case Hanks, A. T.; Huey, L. G.; Lefer, B. L.; Russell, A. G.; Weber, R. J.
- Abstract
Measurements of atmospheric gases and fine particle chemistry were made in the Mexico City Metropolitan Area (MCMA) at a site ~30 km down wind of the city center. Ammonium nitrate (NH4NO3) dominated the inorganic aerosol fraction and showed a distinct diurnal signature characterized by rapid morning production and a rapid mid-day concentration decrease. Between the hours of 08:00-12:45, particulate water-soluble organic carbon (WSOC) concentrations increased and decreased in a manner consistent with that of NO-3 , and the two were highly correlated (R2=0.88) during this time. A box model was used to analyze these behaviors and showed that, for both NO-3 and WSOC, the concentration increase was caused primarily (~75-85%) by secondary formation, with a smaller contribution (~15-25%) from the entrainment of air from the free troposphere. For NO-3 , a majority (~60%) of the midday concentration decrease was caused by dilution from boundary layer expansion, though a significant fraction (~40%) of the NO-3 loss was due to particle evaporation. The WSOC concentration decrease was due largely to dilution (~75%), but volatilization did have a meaningful impact (~25%) on the decrease, as well. The results provide an estimate of ambient SOA evaporation losses and suggest that a significant fraction (~35%) of the fresh MCMA secondary organic aerosol (SOA) measured at the surface volatilized.
- Subjects
MEXICO City (Mexico); MEXICO; ATMOSPHERIC carbon dioxide; ORGANIC synthesis; AEROSOLS; SCIENTIFIC method
- Publication
Atmospheric Chemistry & Physics, 2008, Vol 8, Issue 14, p3761
- ISSN
1680-7316
- Publication type
Article
- DOI
10.5194/acp-8-3761-2008