Measurements of H2O2, major ions and meteorological parameters were made in rain events occurred in downtown Sao Paulo City, Brazil between July 2001 and January 2006. The H2O2 concentration ranged from 0.5 to 78 μmol L-1 with an average of 14.5 μmol L-1. The SO4(2-) and HCOO- concentrations mean were of 13.5 and 9.62 μmol L-1, respectively. The H2O2 concentrations showed a positive and significant correlation with HCOO- (r = 0.70, n = 129, p < 0.0001) suggesting that the production of H2O2 in aqueous phase by consumption of formaldehyde by reaction with OH• radical is a factor which may control the H2O2 levels in the rainwater samples. Estimation of rate of wet deposition of H2O2 shows that nearly 70% of hydrogen peroxide is annually removed from the atmosphere by wet deposition in spring and summer. Sequential rainstorm analyses indicated that lightning activity and rainfall rate can influence the H2O2 contents in rainwater in this area.
hydrogen peroxide; rainwater; air pollution; megacity
