Atmospheric H2O2 field measurements in a tropical environment: Bahia, Brazil

Abstract

Concentrations of H202 in atmospheric gas and liquid phases were determined for the first time in the tropical Southern Hemisphere. Measurements were carried out in the Salvador area, Bahia, 13°S, 38 ° W) both at the seaside and 500 m away from it as well as at 270 km inland, in a rural area, during March-April 1988. Gaseous H20 2 was collected by cryogenic and rain by wet only sampling. Analyses were performed with the peroxyoxalate chemiluminescence method, employing a compact field apparatus. The measured gas phase concentrations ranged from 0.2 to 3.9 ppbv compared to 0.01-0.6 ppbv obtained from measurements with similar methodology in Dortmund (51°30'N, 7°30'E), F.R.G, during summer. The corresponding concentration ranges in rainwater are 0.9-6.8 ppmw (Bahia) and 0.1-2.2 ppmw (Dortmund, summertime). Gas/liquid H202 equilibrium during rain events is only attained at precipitation rates below 1 mmh -1.