Metals in airborne particulate matter at two sampling stations in Mexico City

The metal concentrations of acid and water soluble fractions of PM_2.5 and PM₁₀ at two sampling stations, i.e., Merced and Xalostoc, from the Automatic Monitoring Network in the Mexico city metropolitan Area were studied. Northeast Xalostoc represented a large and complex industrial area with high traffic and poor vegetation, while Merced is an area with high vehicular emissions and high commercial activity. Many of the metals were mainly derived from combustion residues from fuels, tire abrasion, engine, and transmission oils, gasoline, diesel, road pavements, brake lining, and protection barriers. In reference to gaseous pollutants levels, the highest average SO₂ concentrations were observed in Xalostoc and O₃ in the Merced station. Metals were found in both PM₁₀ and PM_2.5, but they occurred extensively in the finer fraction, which was characteristic of anthropogenic pollution sources. pH was a major controlling factor in PM metal solubility. Variability in the quantities of PM soluble metals in acid and water fractions was indicative of the environmentally mobility of the elements. This is an abstract of a paper presented at the 101st AWMA Annual Conference and Exhibition (Portland, OR 6/24-27/2008).