Daniela Montanari Migliavacca

Study of wet precipitation and its chemical composition in South of Brazil

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.

Composição química da precipitação atmosférica no sul do Brasil: estudo preliminar

, NO 3 , F , SO 4 2, Na + , K + , Mg 2+ , NH 4 + , Ca 2+ and Zn, Cu, Fe, Al, Mn. The results showed slightly acidic precipitation and higher concentrations of NH 4 + , Na + , Cl and SO 4 2. Factor analysis applied to the variables studied allowed identifying the major sources. Na + , Cl and Mg 2+ + , Ca 2+ , K + , SO 4 2and NO 3 are from local anthropogenic sources.

Composição química da precipitação úmida da região metropolitana de Porto Alegre, Brasil, 2005- 2007

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+, SO42- 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.

Characterization of wet precipitation by X-ray diffraction (XRD) and scanning electron microscopy (SEM) in the metropolitan area of Porto Alegre, Brazil.

The purpose of this study is to assess the composition of wet precipitation in three sites of the metropolitan area of Porto Alegre. Besides the variables usually considered, such as pH, conductivity, major ions (Cl(-), NO(3)(-), F(-), SO(4)(2-), Na(+), K(+), Mg(2+), NH(4)(+) and Ca(2+)) and metallic elements (Cd, Co, Cr, Cu, Fe, Mn and Ni), the suspended matter was examined by X-ray diffraction (XRD) and scanning electron microscopy (SEM), with energy dispersive system (EDS), for better identification of possible anthropogenic material in this wet precipitation. Results showed an alkaline pH in the samples analyzed and higher concentrations for Na(+), Cl(-) and SO(4)(2-). The acidification and neutralization potential between anions (SO(4)(2-)+NO(3)(-)) and cations (Ca(2+)+Mg(2+)+K(+)+NH(4)(+)) showed a good correlation (0.922). The metallic elements with highest values were Zn, Fe and Mn. Results of XRD identified the presence of some minerals such as quartz, feldspar, mica, clay, carbonates and sulfates. In samples analyzed with SEM, we detected pyroxene, biotite, amphibole and oxides. Cluster analysis (CA) was applied to the data matrix to identify potential pollution sources of metals (natural or anthropogenic) and the association with minerals found in the analysis of SEM.

Análises seqüenciais de agrupamentos aplicadas ao estudo de partículas atmosféricas

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.

Analysis of the sulfate aerosol scavenging processes in the metropolitan area of Porto Alegre (MAPA), RS, Brazil

Abstract The present work aims to study the in-cloud and below-cloud sulfate (SO 4 2- ) scavenging processes by applying numerical models. The BRAMS (Brazilian Regional Atmospheric Modeling System) model was used to simulate the vertical structure of clouds in the metropolitan area of Porto Alegre (MAPA), in southern Brazil, together with the B.V.2 (below-cloud Beheng version 2) scavenging model for wet removal processes, which occur in–cloud (rainout) and below-cloud (washout). Six rainfall events between 2005 and 2007 were selected. They occurred at three sites within the MAPA–Porto Alegre, Canoas, and Sapucaia do Sul–where the SO 4 2- concentrations measured experimentally in wet precipitation, as well as the SO 2 concentrations in the air, were measured. The data were used in the modeling. Results of SO 4 2- scavenging process modeling were in good agreement with those observed experimentally, showing a correlation of 0.73. Results also showed a prevalence of in-cloud scavenging processes, which are responsible for about 70 to 90% of the SO 4 2- concentration found in rainwater, corroborating with data found in the literature.