RESUMO: Projetos de descaracterização de barragens apresentam uma série de questões técnicas que devem ser avaliadas com cautela. Uma dessas questões está relacionada à velocidade de rebaixamento do reservatório de uma barragem de acumulação de água, que pode gerar rupturas do talude de montante. Neste trabalho, estudou-se o rebaixamento do reservatório de uma barragem convencional de mineração, para a etapa conceitual do projeto de descaracterização da estrutura. Por meio de análises transientes de fluxo, utilizandose o programa de elementos finitos Rocscience Slide2 2018, estimou-se o tempo total necessário para se esgotar o reservatório, de forma a atender ao critério de estabilidade da norma NBR 13028, para o talude de montante. A velocidade média encontrada para o completo rebaixamento do reservatório foi considerada aceitável, ficando próxima de valores apresentados na literatura.
Anthropic activities are responsible for the increase in environmental contamination, especially in aquatic systems, demanding studies to assess and monitor contamination levels in different water bodies. We have done a chemical characterization of eleven sediments in order to evaluate the level of contamination by domestic sewage from the Capibaribe River, between the cities of Santa Cruz do Capibaribe and Toritama in the state of Pernambuco, Brazil. The classical analyses were performed, as well as the determination of sterol biomarkers using liquid chromatography coupled to tandem mass spectrometry. Sterol ratios corroborated the presence of fecal-derived organic matter, mainly in the sediments collected in regions of higher population occupation. The multivariate statistical analysis clearly showed the regions from the most contaminated to the least contaminated, indicating the severe contamination by domestic sewage in the region. To the best of our knowledge, this is the first study to assess anthropic contamination of the Capibaribe River by using sterol biomarkers and classical analyses in an integrative data interpretation. This can be helpful when making decisions about preventive and corrective actions for human health concerns.
The Ipojuca River is considered the third most polluted river in Brazil due to the intense anthropogenic activities in the surrounding urban areas. The most important effluent is sewage discharge, which is responsible for considerable contamination. Traditional analyses (infrared spectroscopy, organic matter (OM), elemental analysis and granulometry) and advanced analysis of sterols by liquid chromatography-tandem mass spectrometry (LC-MS/MS) were applied to evaluate the levels of urban contamination from sewage in 10 surface sediment samples from the Ipojuca River, in a stretch located in the Caruaru city, Pernambuco, Brazil. The results pointed to sandy sediments, rich in OM from anthropogenic sources (predominant). Eight different sterols were detected with a total concentration in a range between < limit of quantification (LOQ) and 1,634.4 µg g-1. Coprostanol (fecal biomarker) was detected in high concentrations (557.3 µg g-1) in the sediment collected close to an open-air market (considered the largest in the world), making it the most contaminated in the region. Multivariate statistical analysis revealed areas tending towards contamination and that 90% of sediments were contaminated by sewage. These results can be considered useful for preventive and remedial actions toward promoting human health in this region.
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