Measurements of Heavy Metals in Dry and Wet Deposition in São Paulo City

Abstract

Dry and wet deposition samples were collected and analyzed for copper, lead, cadmium, and zinc in downtown Sao Paulo. The fine and coarse aerosol particles were sampled in winter season while the rainwater samples were collected between February and December 2003. A flow injection analysis system with differential pulse anodic stripping voltammetry detection was used for heavy metals determinations. In wet deposition, the trace metal concentrations (μg/L) showed predominance of zinc (9.8 ± 9.9), followed by Cu (3.6 ± 3.4), Pb (1.7 ± 1.2) and Cd (0.17 ± 0.19). The metal concentrations showed high variability between rain events and larger concentrations were obtained from rainwater samples collected after a long dry period, suggesting an accumulation of pollutants in the atmosphere during the period without precipitation. In fine aerosol particles, lead (38 ng/m3) was the predominant metal while in coarse fraction particles, copper (29 ng/m3) was the trace metal in higher concentration. The results of these measurements indicated that wet deposition was the dominant transport route for heavy metal deposition in this urban area.