Características físico-químicas e comportamento espectral de águas contaminadas por rejeitos de mineração: o caso de Mariana, MG

Abstract

Mining is an economic activity that has many negative impacts on the environment. Water resources are the most affected by mining, the huge dams are built to store the tailings of the activity, and these, can contain leaks, infiltrations and even break. The rupture of the Fundão dam in Mariana caused the greatest environmental disaster in Brazil. On November 5, 2015, the rejects stored in the dam are violently applied in the rivers downstream, in great concentration of the rivers Gualaxo do Norte and Carmo, until at Risoleta Neves and then down Rio Doce, until the Atlantic Ocean. This work, organized in two chapters, analyzed the physical-chemical characteristics of the water of the Gualaxo do Norte and Carmo Rivers in relation to Resolution 357/05 of CONAMA, after the dam disruption of Fundão and related Sentinel-2A and Lansat-8. 36 physico-chemical samples were collected in six by six samples (without satellite scan day, or near data, and without the same points) in six months (April to September 2016), while The images were approved in April, July, August and September 2016 (as of May and June were discarded by the high cloud cover they presented). Random Forest and Linear Regression prediction methods were applied to satellite bands and spectral indices (NDWI, MNDWI, AWEIsh, AWEInsh, WRI, KT Wetness, NDVI). The results showed that the values of metals, color and turbidity and other variables of the polluted waters of the rivers polluted by the mining waste presented values higher than those allowed in CONAMA Resolution 357/05 and highly correlated with the spectral indices, the band 8 Sentinel – 2A and Lansat-8 band 5. It was concluded that as images of the satellites Landsat 8 and Sentinel-2A, it can be used to estimate and monitor how the physico-chemical characteristics of the waters of the rivers affected by the rupture of the Fundão dam, which can be used to verify if waters of other rivers Come to acquire these characteristics as a form of monitoring and other changes caused by the exploitation of ores in the springs