Surface water quality assessment of the main tributaries in the lower São Francisco River, Sergipe

Abstract

Contamination of water body by diffuse and point sources in springs has caused concerns mainly due to restrictions on its quality. The problem becomes more serious when contamination affects water for human consumption, as occurs in the river São Francisco, which supplies several municipalities of Sergipe. In this sense, the objective of the study was to evaluate water quality in eleven tributaries of the São Francisco river in its low course in the period from 2013 to 2014, in order to subsidize decision making by public management bodies operating in the region. For this purpose, it was used the Water Quality Index (WQI) and the Trophic State Index (TSI), as well the hierarchical grouping techniques associated to the samples to compare the different causes of contamination of each source. The lowest WQI values were observed in the rivers Betume and Jacaré and they were associated with high concentrations of coliforms related to the disposal of domestic effluents from the riverside cities. It was observed a tendency to eutrophication in the Jacaré stream, Santo Antônio, Pilões, Papagaio and Capivara rivers demonstrated by the high TSI in the rainy season. The results of the cluster analysis were close to their Euclidean distance, and showed that there were similarity relationships between the different water sources related to their parameters of water quality. In this piece of work, we also used the Factor Analysis resulted in the selection of five factors of water quality indicators which are mainly related to mineral content, organic matter, surface runoff and the level of pollution. Thus, it is concluded that the water quality of the São Francisco river tributaries is at a strong tendency towards contamination and that its tributaries need a constant monitoring for the environmental management decisions to be the most adequate for the sustainable survival of the riverside communities.

Variabilidade espaço-temporal da qualidade da água em área de agricultura irrigada

“…O aumento da DBO durante esse período provavelmente ocorre devido ao aumento dos níveis da matéria orgânica, tal como reportado por Britto et al (2018), onde a maior concentração da matéria orgânica no corpo d'água ocorreu no período seco resultante da evapotranspiração na região. Foram observados valores acima do máximo estabelecido para DBO (até 5 mg L -1 ), apenas para os períodos (P1t¹, P1t² e P2t²).…”

“…Além disso, no período chuvoso, o escoamento superficial das águas das chuvas é somado aos excedentes da irrigação, favorecendo a diluição das concentrações de fósforo. Esses resultados diferem do padrão encontrado por Britto et al (2018), que registraram maiores valores no período chuvoso em que o autor destaca os mecanismos do escoamento superficial.…”

Avaliação da qualidade da água no Rio Grande no segmento entre estação de tratamento de esgoto do município de Barreiras – BA

“…De acordo com a Lei nº 9.433, de 8 de janeiro de 1997, que estabelece a Política Nacional de Recursos de Águas, a água é considerada de domínio público, com recursos naturais limitados, com uso prioritário em caso de escassez, para consumo humano e dessedentação de animais (BRASIL, 1997). Diante disso, a qualidade da água torna-se um parâmetro de grande relevância devido aos diversos contaminantes (poluentes agrícolas, urbanos e industriais) que vem dificultando esse recurso hídrico, causando o surgimento de diversas doenças em todas as formas de vida (BRITTO, 2018).…”

Physical-Chemical Evaluation in Biodisponible Water Samples used for Consumption

“…Fundamental to the life of living beings, water is a vast biomolecule in systems (Brito, 2017). With the increase of the economy and the indiscriminate use of water resources, it can be exhausted since most of this good is unfit for use, 95.1% of which is salt, 4.7% of glaciers and only 0.147% for consumption (Barreto & Bitar, 2011).…”