The impact of trace metals in marine sediments after a tailing dam failure: the Fundão dam case (Brazil)

The present study deals with one of the worst environmental disasters in Brazil so far, the failure of the Fundao tailing dam in the city of Mariana (MG) in 2015. The disaster released over 39.2 million cubic meters of iron ore mining tailings into the Doce River, reaching the southeast coast of Brazil. Data from trace metals and iron in seafloor sediments from Espirito Santo Continental Shelf (ESCS) were evaluated before the disaster and 1 year and 6 months after it. Results revealed contamination of shelf sediments with Zn, Pb, Ni, Cr, Cu and Fe before the disaster, and a noticeable increase in concentrations after the dam failure. Post-disaster, values of geoaccumulation index (NIgeo) for Zn and Fe as high as 8 and 25 were reached, respectively, classifying the samples as extremely polluted. The modified degree of contamination (mCd) values surpassed 32 at many stations which are classified as ultrahigh contaminated. The study also documents the increase of fine material deposition in the study area. Grain size trend analysis (GSTA) corroborated the increase of metal concentrations and mCd values toward the north of Doce River mouth and also at MPA—Costa das Algas.