Phytoremediation Strategies for Rehabilitation of Soils Affected by Red Mud: the Mariana Tailing Dam Collapse (Minas Gerais, Brazil)

Abstract

Brazil has a large number of degraded areas due to iron mining and other elements. In 2015, an iron mining tailings dam belonging to “Samarco Mineração SA”, located in the municipality of Mariana, state of Minas Gerais, collapsed, causing the greatest environmental disaster in the country’s history, due to the spill of 62 million m3 of red mud. The red mud was deposited on slopes, foothills of mountains, intermountain depressions and floodplains, contaminating soils and waters with amines, amides and sodium from the flotation of iron mining residues and causing the formation of surface crusts on the land and hard-setting formation. Different researches were carried out to evaluate and recover degraded soils—Leptosols, Cambisols, Ferralsols, Gleysols and Fluvisols, however the problems are still present and phytoremediation techniques were practically not applied. Phytoremediation is the use of plants to extract, filter, degrade, stabilize, or otherwise reduce mobility, bioavailability, or concentrations of pollutants and stands out as an example of a low cost, minimally invasive approach for the remediation of large-scale contaminated areas. In view of the degraded areas due to the collapse of the “Samarco Mineração SA” tailings dam, this article suggests phytoremediation strategies to rehabilitate the soils in different geomorphological units and the challenges to be faced in the future, pointing out research and the need for the involvement of professionals from different areas of knowledge.