Radiometric signature as an indicator of the level of environmental radiological pollution occurred on the banks of the Rio Doce after the disaster in the Samarco tailings basin in Mariana-MG

The monitoring of the activity concentrations of radionuclides of natural occurrence as ²³⁸U, ²³²Th and ⁴⁰K has been presented in the literature as a means to assess the radiological impact and human exposure in relation to potential sources of radioactivity naturally in estuaries. The rivers Gualaxo, Carmo and Doce suffered major environmental impacts throughout their courses due to the disruption of the tailings dam of the mining company Samarco, Mariana-MG, characterizing it as the biggest accident in the mineral area of this nature throughout the southern hemisphere. The radiometric signature obtained through the activity concentrations of radionuclides of natural occurrence such as ⁴⁰K, ²³⁸U, ²³²Th and sons in sediment or soil is an important indicator of radiological environmental pollution caused by accidents in basins of tailings. This work aimed to determine by gamma spectrometry natural radioactivity levels in sediments of the estuary of the Doce River, from samples collected in the same localities before (10/09/2014) and after the accident (27/11/2015), to obtain the variation on the indicators of the level of pollution environmental radiometric, namely radio equivalent (Ra_eq) and external radiological risk indices (H_externo) and (H_interno) and compare them with the global reference levels. Concentration values for ²³⁸U, ²³²Th in sediments, after the breaking of the dam of Fundão, had increased 30% and 60%, respectively, and 17% reduction to ⁴⁰K. The results suggest that soil and sediments on the banks of the rivers Gualaxo, Carmo and Doce were contaminated with TENORM material released by the tailings basin, reflecting the extent of radiological environmental pollution level this after the disaster. (author)