This work aims to quantify the wet precipitation the Metropolitan Area of Porto Alegre (MAPA), in southern Brazil, through the analysis of major ions (by ion chromatography) and metallic elements (ICP/AES). By principal components analysis and cluster analysis was possible to identify the influence of natural and anthropic sources in wet precipitation. The results indicated of the higher contribution to the ions NH4+, SO4(2-) and Ca2+. Thus it was possible to identify the contribution of anthropogenic sources in wet precipitation in the study area, such as power plants, oil refineries, steel and vehicle emissions.

O objetivo deste estudo é analisar a composição química da precipitação úmida em amostras coletadas em três estações na região de Candiota no Estado do Rio Grande do Sul (RS) Brasil. Amostras foram coletadas em 2004. Variáveis analisadas na precipitação úmida foram pH, condutividade e concentração de Cl-, NO3-, SO4(2-) F-, Na+, Ca2+, Mg2+, K+, NH4+, Cu, Zn, Fe, Mn, Pb, Ni, Cd, Co e Cr. Distribuição no tempo de SO2 e NO2 também foi avaliada. Resultados mostraram que pH < 5,6 são encontrados em sua maioria no aeroporto de Candiota (85%), seguidos pelo Aceguá (72%) e Três Lagoas (65%). Fator de Enriquecimento dos íons estudados na deposição úmida revelou maior enriquecimento de Ca2+ e SO4² em Três Lagoas. Análise Fatorial aplicada aos metais e íons maiores permitiu identificação de fontes maiores. Enquanto Cl-, Na+, Mg2+ são de origem marinha, SO4(2-), NO3-, NH4+, F- são provenientes de fontes antropogênicas. Exceto Fe e Mn originários de poeira do solo, os metais estudados mostraram ter influência antropogênica. A média da concentração de SO2 e NO2, bem como SO4(2-) e NO3- na precipitação úmida na região de Candiota mostrou maiores concentrações durante os meses mais quentes.

The purpose of this study is to analyze the chemical composition of wet precipitation in samples collected at three stations in the Candiota region in the Brazilian state of Rio Grande do Sul (RS). Samples were collected in 2004. Variables analyzed in wet precipitation were pH, conductivity, and concentration of Cl-, NO3-, SO4(2-) F-, Na+, Ca2+, Mg2+, K+, NH4+, Cu, Zn, Fe, Mn, Pb, Ni, Cd, Co, and Cr. SO2 and NO2 distribution over the time were also evaluated. Results have showed that pH < 5.6 are found mostly at Candiota airport (85%), followed by Aceguá (72%) and Três Lagoas (65%). Enrichment Factor of the studied ions in wet deposition revealed higher Ca2+ and SO4(2-) enrichment in Três Lagoas. Factor Analysis applied to metals and major ions allowed identifying the major sources. While Cl-, Na+, Mg2+ are of marine origin, SO4(2-), NO3-, NH4+ ,F- come from anthropogenic sources. Except for Fe and Mn originating from the soil dust, the metals studied showed to have anthropogenic influence The average SO2 and NO2 concentration, as well as SO4(2-) and NO3- in wet precipitation in the Candiota region showed higher concentrations during the warmer months.

The present work is a preliminary study of total and wet precipitation in the Candiota region, RS. The samples were collected from January to June 2001 at four different sites. The following variables were analysed: pH, conductivity, alkalinity, Cl-, NO3-, F-, SO4(2-), Na+, K+, Mg2+, NH4+, Ca2+ and Zn, Cu, Fe, Al, Mn. The results showed slightly acidic precipitation and higher concentrations of NH4+, Na+, Cl- and SO4(2-). Factor analysis applied to the variables studied allowed identifying the major sources. Na+, Cl- and Mg2+ have their origin in sea salts and NH4+, Ca2+, K+, SO4(2-) and NO3- are from local anthropogenic sources.

The present paper has as objective to apply a sequential Cluster Analysis to the atmospheric particles: Hierarchical Cluster Analysis followed by Nonhierarchical Cluster Analysis. The hierarchical cluster analysis results were used as start point for the nonhierarchical cluster analysis as an agglomerative technique. These particles were taken from two areas of the metropolitan region of Porto Alegre, Charqueadas and Sapucaia do Sul., from may /97 to may/98, using a High Volume Sampler (Hi-Vol). Around 10,000 particles were analysed by Scanning Electron Microscope with Energy-Dispersive X-Ray microanalysis (SEM-EDS). The Hierarchical Cluster Analysis allowed the identification of five groups of particles, whose amounts were differentiated according to the summer and the winter campaigns. The abundance of each type of particles inside each group according to the different sections was verified by the Nonhierarchical Cluster Analysis, resulting in information about the emissions sources. The groups of particles of Si/Al and Si and of Fe/Zn and Fe for Charqueadas were more significant in section 2 and 3 (NW and W wind directions) and in section 1 (SE wind direction), evidencing the influence of the coal power plant and steel industry, respectively located in these quadrants. In Sapucaia do Sul the data were more heterogeneous, causing a certain difficulty to identify the source as anthropogenic. Nevertheless the group of particles containing Fe was found in sectors of NW/W wind directions which shows the influence of the steel plant.