Evaluation of the Atmospheric Deposition in an Urban Region in South Brazil

Abstract

The purpose of the present study is to analyse the chemical composition of bulk and wet atmospheric deposition samples in the Guaiba Hydrographic Basin (GHB), in south Brazil. Samples of bulk and wet deposition were analysed during a 1-year's period (January to December 2002) at three different stations, i.e., 8∘ Distrito and CEASA stations in the city of Porto Alegre, and Charqueadas station, in Charqueadas city. Conductivity, pH, Cl−, NO3−, F−, SO42 −, Na+, K+, Mg2 +, NH4+ and Ca2 + were determined. The pH presented an average value between 4.75 and 7.45. Enrichment factor was characterised based on groups of acid (pH 5.65) samples. For most of the studied ions, EF in bulk deposition was higher in alkaline samples, while in wet deposition there was little difference between acid and alkaline samples. The Multivariate Analysis technique, i.e. the Canonical Correlation Analysis (CCA), determined relationships between the two different data set (chemical and meteorological), identified the source (anthropogenic or natural) of the studied variables.