Atmospheric precipitation and chemical composition of an urban site, Guaíba hydrographic basin, Brazil

The purpose of the present work was to study the chemical composition of bulk and wet atmospheric precipitation in the Guaíba Hydrographic Basin, in South Brazil. The samples were analyzed from January to December 2002 at three different stations, i.e., 8° Distrito and CEASA stations in the city of Porto Alegre, and Charqueadas station, located in the city of same name. The bulk and wet precipitation were analyzed for conductivity, pH, Cl−, NO3−, F−, SO42−, Na+, K+, Mg2+, NH4+, Ca2+, Cu, Zn, Mn, Fe and Al. The pH values in the samples of atmospheric precipitation ranged between 4.75 and 7.45. The analysis of linear regression applied to the set of studied variables showed that neutralization occurred in samples of bulk and wet precipitation. It was found that the Cl present in samples of atmospheric precipitation originated from sea salts and anthropogenic sources. The principal components analysis (PCA) identified the main anthropogenic sources within the Guaíba Hydrographic Basin (GHB). Cluster analysis grouped the events identified for each station in the PCA in association with the meteorological data.