PM1 Chemical Characterization during the ACU15 Campaign, South of Mexico City

The “Aerosoles en Ciudad Universitaria 2015” (ACU15) campaign was an intensive experiment measuring chemical and optical properties of aerosols in the winter of 2015, from 19 January to 19 March on a site in the south of Mexico City. The mass concentration and chemical composition of the non-refractory submicron particulate matter (NR-PM1) was determined using an Aerodyne Aerosol Chemical Speciation Monitor (ACSM). The total NR-PM1 mass concentration measured was lower than reported in previous campaigns that took place north and east of the city. This difference might be explained by the natural variability of the atmospheric conditions, as well as the different sources impacting each site. However, the composition of the aerosol indicates that the aerosol is more aged (a larger fraction of the mass corresponds to sulfate and to low-volatility organic aerosol (LV-OOA)) in the south than the north and east areas; this is consistent with the location of the sources of PM and their precursors in the city, as well as the meteorological patterns usually observed in the metropolitan area.