21/06/2016
Samarco mine tailings do not contain any contaminants, consisting basically of silica (sand) and iron oxides, in addition to aluminum oxides in lesser quantity. These are the results of the ongoing studies performed by Samarco under the guidance of the environmental agencies of Minas Gerais and Espírito Santo, with the objective of determining the conditions of the water and the aquatic biota along the Doce River watershed, impacted by the collapse of the Fundão dam.
The results obtained by Samarco with regard to the composition of the tailings are similar to those found by independent studies of the Brazilian Geological Service (CPRM) and the National Water Agency (ANA), which had found that, based on the samplings made, in November of 2015, there was no arsenic, cadmium, lead or similar metal in concentrations above the limits determined by law. In addition, an assessment of the dam break showed that 87% of the tailings were contained within the first 120 kilometers, between the Fundão dam and the Candonga Reservoir (of the Risoleta Neves HPP), in Minas Gerais.
In addition to the chemical and physical analyses of the water and sediments, tests were also made with live organisms to measure the effective impact of the tailings on the aquatic biota. These studies showed that the tailings are not toxic, however the physical impacts related to the large quantity of particulate matter were relevant and are specifically associated with the moment of the passage of the plume.
Studies had been made of the bioaccumulation of metals in the Doce River prior to the passage of the turbidity plume, showing that even before its passage, the fish fillets already had chromium content above the limit established by the National Sanitary Inspection Agency (Anvisa). Tests made after the passage of the plume did not show any changes in the quality of the fish fillets.
As for the marine organisms, the findings pointed to the presence of arsenic, selenium and zinc at levels above those established by Anvisa. Based on scientific studies, one may consider that there are several sources of these elements along the coast close to the mouth of the Doce River, and Samarco’s activities and the collapse of the dam did not affect the concentrations of these elements in the sediment, in the water, and in the fauna analyzed. The studies that focus on the analysis of metals in fish will continue to be developed jointly with Instituto Chico Mendes de Conservação da Biodiversidade (ICMBio).
