Evaluation of violations in water quality standards in the monitoring network of São Francisco River basin, the third largest in Brazil

Abstract

The São Francisco River is the largest river located entirely within Brazil, and water scarcity problems have been a major concern of Brazilian society and government. Water quality issues are also a concern and have worsened with the recent intensification of urbanization and industrialization. In this study, violations to water quality standards established by local legislation were calculated as a percentage for 26 selected parameters over a monitoring period of 14 years. The violation percentages were analyzed spatially using the Kruskal-Wallis test, followed by multiple comparison analysis. Temporal analysis was performed using the Mann-Kendall test and Spearman correlation. Some parameters could be identified as cause for concern due to high violation levels, such as the fecal coliform indicator (FCI) and phosphorus-both related to domestic and effluent disposal without treatment or with insufficient treatment-and color, turbidity, manganese, and total suspended solids-which can be affected by erosive processes of natural and anthropogenic causes. The study found that these violations are concentrated in the most urbanized and industrialized areas of the basin. Some metallic parameters, such as iron and arsenic violations, may be related to mining activities in the rich soil of the Iron Quadrangle area located within the Minas Gerais State. Trend analysis results indicated that most monitoring stations did not have significant modification (elevation or reduction) trends over time, which, together with the high violation percentages, might indicate the maintenance of a scenario of constant pressure upon water resources, in particular in those more urbanized areas.

Spatial-temporal analysis of the surface water quality of the Pará River Basin through statistical techniques

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Zooplankton richness at the inlet of the La Mancha lagoon, during monthly and diel samplings

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Avaliação Espacial da Qualidade da Água da Bacia Hidrográfica do Rio Araçuaí - Minas Gerais

“…Com o passar do tempo, os programas de monitoramento geram extensos bancos de dados, cuja análise pode ser morosa e complexa (TRINDADE et al, 2016). Nesse contexto, o uso de técnicasestatísticas pode contribuir para um melhor aproveitamento dos resultados do monitoramento, contribuindo para a gestão dos recursos hídricos (COSTA et al, 2017). A qualidade das águas da bacia do Rio Araçuaí, localizada na região nordeste do estado de Minas Gerais, vem sendo monitorada em diversos pontos, desde o ano de 1997, no âmbito do Projeto "Águas de Minas" (IGAM, 2017).…”