Rainwater composition in northeast Uruguay

Abstract

The chemical composition of rainfall in northeast Uruguay in 1999 and 2000 and the sources that contribute to the rainwater chemistry are assessed in this study, contributing to a limited knowledge base of rainwater quality in South America. Principal factor analysis and cluster analysis indicate that four main source groups influence the rainfall chemistry over a range of spatial scales. Terrigenous sources (e.g. rock, soil and dust) and agricultural sources (e.g. livestock and crop fertilization) contribute to rainwater chemistry on a local and sub-regional scale. Influx of marine air from the Atlantic Ocean has a regional-scale influence while biomass burning contributes at both a local and subregional scale (e.g. fuel wood, and agroindustries) and through long-range transport (forest fires and land clearing). As may be expected in this area dominated by agriculture, the concentrations of ions that are indicative of industrial emissions, NO 3 À and SO 4 2À , are typical of background measurements. The current data are limited, but provide an indication of rain quality and the sources that influence its chemistry in Uruguay. It may be inferred that large-scale biomass burning in the central parts of the continent influence rainwater chemistry on a scale far larger than indicated by the Uruguayan network. Similarly, but to lesser extent, the influx of marine air off the Atlantic Ocean has a greater regional-scale influence than suggested by these data. r

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

“…This result is confirmed by the fact that the highest concentrations for these ions were found at this site. Similar findings were obtained by Migliavacca et al (2005) and Zunckel et al 2003) in studies at the same site. As for Factors 1 and 3 (Fig.…”

“…The pH value found at Aceguá is slightly higher than those determined in previous studies. However, this value is still lower than those found by Zunckel et al (2003) at the border with Uruguay (Aceguá-Uruguay) between 1999 and 2000. The values found at the time were higher than 5.6.…”

“…The source that could explain the enrichment in K + is earth particles, quite significant in the area. Other studies done in the area and in a nearby State showed significant quantities for K + (Migliavacca et al 2004b, Zunckel et al 2003. Table IV and Figures 4a, b and c show the average concentration of metals at the three sampling sites from January to December, 2004.…”

Composição química da chuva e aporte atmosférico na Ilha Grande, RJ

“…A NH 3 não participa expressivamente de reações fotoquímicas 2 e seu principal papel na atmosfera urbana é a neutralização dos ácidos H 2 SO 4 e HNO 3 , produtos da oxidação dos gases SO 2 e NO x (NO + NO 2 ), dando origem a sais de amônio [NH 4 HSO 4 , (NH 4 ) 2 SO 4 e NH 4 NO 3 ] que ocorrem predominantemente associados à faixa de partículas finas (diâmetro aerodinâmico < 2,5 µm) e podem ser transportadas a longas distânci-as 2 . Portanto, estas partículas podem ter como procedência as emissões antrópicas de áreas situadas a centenas ou milhares de quilô-metros de distância [29][30][31] . No caso da RMRJ, localizada a nordeste da Ilha Grande, as potenciais fontes antrópicas emissoras de amônia (NH 3 ) para a atmosfera são os sistemas de esgotamentos sanitários, rios e canais receptores de grandes quantidades de esgotos não tratados, depósi-tos de lixo e aterros sanitários, veículos 32 e queima de biomassa no período de estiagem 33 .…”

Ion input via rainwater in the southwestern region of Rio Grande do Sul, Brazil

“…In a study conducted in Uruguay by Zunckel et al (2003), the authors observed the existence of significant correlations between concentrations of chemical elements in rainwater. A correlation was observed between chlorine, sodium and magnesium due to the marine source contribution to chemical characteristics of rainwater.…”