Time variations of lead, copper and cadmium concentrations in aerosols in Ann Arbor, Michigan☆

The atmosphere in Ann Arbor, 50 km west of Detroit, was sampled for aerosol particles for 2-h periods over a 42-h interval Friday to Sunday, April 26-28, 1968, using a mod&d seven-state Andersen cascade impactor and a glass backup filter. The eight particle size fractions from each sampling were analyzed separately for lead, copper, and cadmium by means of anodic stripping voltammetry (ASV) with a composite mercury graphite electrode. Average particle size distributions were similar for the three elements over 0.1 Pb> 600 ng me3, 1000~ Cu> 100 ng rnm3, and 300~ Cd> 100 ng rnm3. Two prominent maxima were observed at 0200-2400 EST, April 27, and suggested a wind shift from north to east. The results imply that some of the Cu and Cd, and much of the Pb at the maximum times came from the Detroit sector by easterly winds and that a 2-h sampling period is adequate for correlating changes in the environment with mesoscale meteorological parameters.