QUANTIFICATION OF A MICROBIOLOGICAL BIOMARKER IN THE TRIBUTARY AFFECTED BY A MAJOR ENVIRONMENTAL DISASTER OCCURRED IN THE DOCE RIVER BASIN

The bacteria Escherichia coli are an indicator of fecal contamination, indicating water pollution, release of domestic sewage without treatment in the waters. In this context, we analyze the spatial distribution of E. coli bacteria in the Gualaxo do Norte River basin. River affected in 2015 by the rupture of the Fundão dam in the district of Bento Rodrigues, Mariana/Brazil, released around 50 million m³ of iron ore tailings. Despite the presence of pathogens water of the Gualaxo do Norte River basin has been used for irrigation, and for animal and human consumption. In this sense, this study was 27 sampling points along the basin that were monitored monthly during a hydrological cycle, from July 2016 to June 2017 for the presence and quantification of E. coli. From there, a quantitative map of these E. coli concentrations was generated using ArcGIS 10.2® software. We discuss our results based on the National Environmental Council (Conselho Nacional de Meio Ambiente or CONAMA) that published the Resolution nº 357 in 2015. Rainy periods presented greater disagreement with the legal limits, about 70%. According to studies, fecal pollution concentrations are increased during periods of higher precipitation, since microorganisms can be carried to the water bodies. The main source of pollution can be the discharge of domestic effluents into bodies of water, since the percentage of sewage treatment is very low in the river basin. Taking into account unplanned indirect reuse, which is characterized by the release of water used in some human activity, in the environment, being captured downstream in an uncontrolled way, this becomes an aggravating factor, since it increases the risks to health human and animal. The spatial distribution of the data will allow, in particular, management to mitigate disease risks at strategic locations, to minimize the impacts caused by bacterial contamination and other pathogens that E. coli can co-indicate, such as viral and parasitic, in view the improvement of human, animal and environmental health. The results of this research constitute a current and systemic study related to the Gualaxo do Norte River basin and more importantly, may serve as a subsidy for the management of the source, in order to ensure the environmental, economic and social sustainability of the region degradation occurred.