River Doce estuary soil remediation through metals immobilization through pyritization with gypsum and vinasse

• Grant number: 20/06224-1
• Support type: Scholarships in Brazil - Scientific Initiation
• Effective date (Start): August 01, 2020
• Effective date (End): July 31, 2021
• Field of knowledge: Agronomical Sciences - Agronomy - Soil Science
• Principal researcher: Tiago Osório Ferreira
• Grantee: Maíra Pereira Kanegae
• Home Institution: Escola Superior de Agricultura Luiz de Queiroz (ESALQ). Universidade de São Paulo (USP). Piracicaba , SP, Brazil

Abstract

The Fundão dam rupture in Mariana (MG) in 2015, one of the biggest global environmental disasters, launched mining tailings in the river "Doce" estuary. These mining tailings are composed predominantly of iron oxides, which are susceptible to reduction and oxidation in estuarine conditions, releasing the associated trace metals. The river "Doce" estuary differs from most estuaries in that it does not receive large amounts of seawater. This results in low availability of sulfate, disfavoring sulfate reduction, and consequently the immobilization of metals via pyritization. The immobilization of metals via sulfidation - reduction of sulfate to sulfide - and immobilization of metals in the acid-volatile sulfide (AVS) and pyrite fractions is a process that occurs naturally in estuarine environments and is extremely important in the immobilization of metals. Thus, it is proposed to test the hypothesis that the addition of sulfate, in the presence of a labile C source, will promote an increase in the degree of pyritization (DOP) and an increase in the immobilization of trace metals, measured through the degree of pyritization of trace metals (DTMP). To test this hypothesis, the tailings deposited in the river Doce estuary will be incubated for five weeks in an experiment. The experiment will be carried out in a completely randomized design with three replications. The plot will consist of six treatments: two control treatments (incubation only with water and only with the addition of C) and four doses of sulfate + addition of C. The subplots will be the evaluation times (5 weeks). The pH, Eh, and electrical conductivity of the solution will be determined weekly. In the solution, the levels of metals, sulfate, sulfide, and Fe 2+ will be determined. In the solid phase, sequential extraction of the iron and metal fractions will be carried out in order to determine the DOP and DTMP in each treatment. The extraction of volatile sulfides in an acid medium (AVS) will also be carried out. The addition of sulfate and a labile C source is expected to increase DOP, DTMP and the immobilization of metals in AVS, reducing the availability of metals in the solution that can become risk contaminants for the entire food chain.

Scientific publications

(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)

FERREIRA, AMANDA D.; QUEIROZ, HERMANO M.; KANEAGAE, MAIRA P.; NOBREGA, GABRIEL N.; OTERO, XOSE L.; BERNARDINO, ANGELO F.; FERREIRA, TIAGO O. Gypsum Amendment Induced Rapid Pyritization in Fe-Rich Mine Tailings from Doce River Estuary after the Fundao Dam Collapse. MINERALS, v. 11, n. 2 FEB 2021. Web of Science Citations: 0.