Qualidade da água durante a IV expedição ao baixo rio São Francisco para fins de preservação e abastecimento dos municípios ribeirinhos

Abstract

The São Francisco River, stretching 2,800 km, is divided into upper, middle, sub- middle, and lower regions, with the lower region accounting for 5% of the basin. The objective of this study was to evaluate water quality along the lower river and understand the impact of variations in flow and climatic conditions, as well as to suggest improvements for its preservation. The research adopted a quantitative and descriptive approach, collecting water samples at various points along the river, in several municipalities up to its mouth. Physical/chemical parameters and microbiological parameters were analyzed. The analysis compared the results with the standards set by CONAMA Resolution No. 357/2005 and assessed variations due to changes in flow and climate. The results revealed significant variations in water quality, with high levels of fecal coliforms and Escherichia coli in several locations, such as Pão de Açúcar and Penedo, indicating severe pollution associated with improper sewage disposal. The analysis showed that water retention during dry periods and release during wet periods affect pollutant concentrations, exacerbating pollution. Parameters such as potassium and nitrite exhibited concerning variations, especially near the river’s mouth, suggesting the presence of additional contaminants. Although some parameters, like pH and ammonia, met potability standards, electrical conductivity and total dissolved solids (TDS) increased towards the river’s mouth, indicating the presence of pollutants. The conclusions highlight the urgent need for improvements in sanitation infrastructure and sewage treatment in riparian areas. The persistence of high contamination levels and variations in pollutant concentrations underscore the inadequacy of current control measures. It is recommended to expand and modernize sanitation networks and conduct continuous water quality monitoring to identify and address emerging problems.