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Redox processes controlling Fe OXIDE-ASSOCIATED metals dynamics in Rio Doce estuary sediments after the Mariana dam disaster

Grant number: 19/17413-2
Support type:Scholarships abroad - Research Internship - Doctorate
Effective date (Start): October 07, 2019
Effective date (End): June 21, 2020
Field of knowledge:Agronomical Sciences - Agronomy - Soil Science
Principal Investigator:Tiago Osório Ferreira
Grantee:Hermano Melo Queiroz
Supervisor abroad: Samantha Ying
Home Institution: Escola Superior de Agricultura Luiz de Queiroz (ESALQ). Universidade de São Paulo (USP). Piracicaba , SP, Brazil
Local de pesquisa : University of California, Riverside (UCR), United States  
Associated to the scholarship:18/04259-2 - Iron biogeochemistry and its control on dynamics of trace metals in the soils of Doce River estuary after the "Mariana disaster", BP.DR

Abstract

This project aims to examine the dynamics of iron oxyhydroxides and associated toxic metals sourced from mine tailings deposited in the Rio Doce estuary as a result of the Fundão Dam disaster in 2015. Recently, studies have reported an increase in the total iron and trace metal content in soils of the Rio Doce estuary; however, few studies have determined the mechanisms that control trace metal fate and transport. Iron(III) oxyhydroxides are considered one of the most important mineral groups in attenuating the mobility of trace metals in estuarine ecosystems. The retention capacity of Fe(III)oxyhydroxides for toxic metals depends on particle size, morphology, crystallinity, and sensitivity of both Fe(III) minerals and trace metals to redox changes. Tailings of the Fundão Dam disaster have deposited in an estuarine environment that undergoes frequent redox fluctuations from natural diurnal water-level water changes or due to the seasonal effect (seasons wet and dry). Within these dynamic soils, redox changes will occur in different ways as reducing and oxidizing conditions. Thus, the objectives of this project will be to (i) to determine the seasonal effect on control of Fe and metals concentrations due to biogeochemical shifts as redox conditions; and (ii) determine the effect of iron reduction processes on transformation of tailings materials and effect on release rate and transport of associated toxic metals. The results of this study will provide foundational knowledge of metals behavior under estuarine conditions, mechanisms iron oxyhydroxides to control the bioavailability of metals in soils and an assessment of the potential for trace metal release from tailings to the surrounding environment.