Trace metals in the water and margin sediments of the Rio Doce Basin in Linhares municipality, ES, Brazil

Abstract

The Rio Doce Basin (DRB) is the largest freshwater source in Espírito Santo (ES) state, Brazil. In November 2015, the disruption of the iron tailings dam in the Mariana municipality, Minas Gerais state, Brazil, severely affected this river. In this study, we showed the trace metals concentrations in the water and margin sediments of the DRB during the dry and wet seasons. This new data was obtained in 2011, prior to the environmental disaster caused by disruption of the dams. We observed Cr, Ni and Pb contaminations in the sediments. The concentrations of these elements in the high river flow (wet season) were higher than the guideline values (GV) of level II and geoacumulation Index (I_geo). However, Fe and Mn concentrations were well above the GV in the wet season. The levels of these two elements were lower than the values found in the region's Haplic Cambisol. Furthermore, the comparison between our data and those of the technical reports released after the dams rupture shows that iron ore mine tailings greatly alter the trace metals concentration in water and sediments. However, we have observed a trend of resilience that requires more systematic and careful studies in DRB.