Evaluating the Water Quality of Springs in Paracatu de Baixo after the Fundão Dam Collapse

Resumo

The collapse of the Fundão Dam in Mariana municipality (MG, Brazil), in 2015, resulted in approximately
60 million cubic meters of iron ore tailings being directly released into the Doce River watershed. Although
it is presumed that the dam sludge is primarily composed of Si, Fe, and Mn, the accident occurred in an
area with a geochemical source of arsenic, an anthropogenic source of mercury, and contaminated by
other potentially toxic metals and metalloids (also with geochemical and anthropogenic sources); their
mobilization along the river course is therefore highly probable. Therefore, this study aimed to analyze
the water of Paracatu de Baixo, a sub-district of Mariana that was devastated by the Fundão Dam sludge,
to evaluate the influence of sludge dust on the spring waters used by the few remaining residents who use
this water for consumption and for irrigating vegetables they consume and sell. In this study, samples of
rainwater and spring water were collected during both the rainy and sunny seasons in different locations
in Paracatu de Baixo. On both dates, the physicochemical parameters studied (pH, turbidity, conductivity,
hardness, nitrate, nitrite, total solids, and dissolved oxygen) were within the limits allowed by Resolution
357/05 of CONAMA and Portaria 1469. Ba, Cu, Zn, Al, Fe, and Mn metals were determined in the
samples, but only the Al and Fe elements exceed the value recommended by the Brazilian legislation.
Several of the metals found showed higher concentrations during the rainy season, which indicates that
they are becoming available due to lithological issues rather than being caused by sludge dust.