Mine tailings in a redox-active environment: Iron geochemistry and potential environmental consequences

Author(s)

Queiroz, Hermano Melo ^[1] ; Ruiz, Francisco ^[1] ; Deng, Youjun ^[2] ; de Souza Junior, Valdomiro S. ^[3] ; Ferreira, Amanda Duim ^[1] ; Luis Otero, Xose ^[4] ; Camelo, Danilo de Lima ^[5] ; Bernardino, Angelo Fraga ^[6] ; Ferreira, Tiago Osorio ^[1]

Affiliation

^[1] Univ Sao Paulo, Luiz de Queiroz Coll Agr, Dept Soil Sci, Piracicaba, SP - Brazil

^[2] Texas A&M Univ, Dept Soil & Crop Sci, College Stn, TX 77843 - USA

^[3] Univ Fed Rural Pernambuco, Dept Agron, Av Dom Manoel de Medeiros S-N, BR-52171900 Recife, PE - Brazil

^[4] Univ Santiago de Compostela, Fac Biol, CRETUS Inst, Dept Edafol & Quim Agr, Santiago De Compostela - Spain

^[5] Univ Fed Espirito Santo, Dept Agron, Alegre, ES - Brazil

^[6] Univ Fed Espirito Santo, Dept Oceanog, BR-29075910 Vitoria, ES - Brazil

• Document type: Journal article
• Source: Science of The Total Environment; v. 807, n. 3 FEB 10 2022.
• Web of Science Citations: 1

Abstract

Iron (Fe) oxyhydroxides provide many functions in soils, mainly owing to their large surface area and high surface charge density. The reactivity of Fe oxyhydroxides is function of their mineralogical characteristics (e.g., crystallinity degree and crystal size). Detailed studies of these features are essential for predicting the stability and reactivity of these minerals within soil and sediments. The present study aimed to evaluate geochemical changes in Fe-rich tailings after the world's largest mining disaster in SE Brazil (in 2015) and to predict the potential environmental implications for the estuary. The mineralogical characteristics of the tailings were studied at three different times (2015, 2107, and 2019) to assess how an active redox environment affects Fe oxyhydroxides and to estimate the time frame within which significant changes occur. The study findings indicate a large decrease in the Fe oxyhydroxides crystallinity, which were initially composed (93%) of highly crystalline Fe oxyhydroxides (i.e., goethite and hematite) and 6.7% of poorly crystalline Fe oxyhydroxides (i.e., lepidocrocite and ferrihydrite). Within 4 years the mineralogical features of Fe oxyhydroxides had shifted, and in 2019 poorly crystalline Fe oxyhydroxides represented 47% of the Fe forms. Scanning electron microscope micrographs and the mean crystal size evidenced a decrease in particle size from 109 nm to 49 nm for goethite in the d111 direction. The changes in mean crystal size increased the reactivity of Fe oxyhydroxides, resulting in a greater number of interactions with cationic and anionic species. The decreased crystallinity and increased reactivity led to the compounds being more susceptible to reductive dissolution. Overall, the findings show that the decrease in crystallinity along with higher susceptibility to reductive dissolution of Fe oxyhydroxides can affect the fate of environmentally detrimental elements (e.g., phosphorus and trace metals) thereby increasing the concentration of these pollutants in estuarine soils and waters. (c) 2021 Elsevier B.V. All rights reserved. (AU)

• FAPESP's process: 19/17413-2 - Redox processes controlling Fe oxide-associated metals dynamics in rio Doce estuary sediments after the Mariana dam disaster
• Grantee: Hermano Melo Queiroz
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate
• FAPESP's process: 19/14800-5 - Estuarine plants and their control in metals biogeochemistry in soils impacted by the `Mariana disaster´
• Grantee: Amanda Duim Ferreira
• Support Opportunities: Scholarships in Brazil - Doctorate
• FAPESP's process: 19/19987-6 - Soils and plants of the Rio Doce estuary controlling the biogeochemistry of iron and metals in response to the Mariana (MG) disaster
• Grantee: Tiago Osório Ferreira
• Support Opportunities: Regular Research Grants
• FAPESP's process: 18/04259-2 - Iron biogeochemistry and its control on dynamics of trace metals in the soils of Doce River estuary after the "Mariana disaster"
• Grantee: Hermano Melo Queiroz
• Support Opportunities: Scholarships in Brazil - Doctorate
• FAPESP's process: 18/08408-2 - Comparative studies of the mineral transformation of iron oxide nanoparticles in mine-tailing affected sediments and soils and their impacts on mobilization and fixation of heavy metals under two contrasting redox environments
• Grantee: Tiago Osório Ferreira
• Support Opportunities: Regular Research Grants
• FAPESP's process: 19/18324-3 - Soil quality and stabilization of organic matter of technosols developed from limestone mine spoils
• Grantee: Francisco Ruiz
• Support Opportunities: Scholarships in Brazil - Doctorate