Potentially toxic elements in iron mine tailings: Effects of reducing soil pH on available concentrations of toxic elements

Potentially toxic elements in iron mine tailings: Effects of reducing soil pH on available concentrations of toxic elements

Tailings from iron mining are characterized by high concentrations of iron and manganese oxides, as well as high pH values. With these characteristics, most of the potentially toxic elements (PTE) contained in the tailings are somewhat unavailable. The aim of the present study was to evaluate how a...

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Bibliographic Details
Published in:Environmental research Vol. 215; no. Pt 2; p. 114321
Main Authors: da Silva, Ana Paula Valadares, Silva, Aline Oliveira, Lima, Francielle Roberta Dias de, Benedet, Lucas, Franco, Aline de Jesus, Souza, Josimara Karina de, Ribeiro Júnior, Alexandre Carvalho, Batista, Éder Rodrigues, Inda, Alberto Vasconcellos, Curi, Nilton, Guilherme, Luiz Roberto Guimarães, Carneiro, Marco Aurélio Carbone
Format: Journal Article
Language:English
Published: Netherlands Elsevier Inc 01-12-2022
Subjects:
Cadmium
Environmental degradation
Fundão dam
Hydrogen-Ion Concentration
Iron - analysis
Iron - toxicity
Lead
Manganese
Mining
Oxides
Pentetic Acid
Soil
Soil contamination
Soil extractants
Soil Pollutants - analysis
Soil Pollutants - toxicity
Water
Soil extractants
Fundão dam
Environmental degradation
Soil contamination
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Summary:Tailings from iron mining are characterized by high concentrations of iron and manganese oxides, as well as high pH values. With these characteristics, most of the potentially toxic elements (PTE) contained in the tailings are somewhat unavailable. The aim of the present study was to evaluate how a reduction in the pH of iron mine tailings may affect PTE availabilities. The tailings were collected on the banks of the Gualaxo do Norte River (Mariana, MG, Brazil), one of the main areas impacted by the rupture of the Fundão Dam (Barragem de Fundão). A completely randomized experimental design was used, including five pH values (6.4, 5.4, 4.3, 3.7, and 3.4) and five replications. The concentrations of the PTE (Ba, Cr, Cd, Co, Cu, Fe, Mn, Pb, Ni, and Zn) were determined after extraction following different methodologies: USEPA 3051A, DTPA, Mehlich-1, Mehlich-3, and distilled water. A comparison of the available concentrations of the elements in the tailings with those in a soil not impacted by tailings shows that Cr, Cd, Cu, Fe, Mn, Ni, Ba, and Co were higher in the soil impacted by the tailings. The different methods used for evaluating the availability of PTE in the tailings at various pH exhibited the following decreasing order in relation to the quantity extracted: Mehlich-3 > Mehlich-1 > DTPA > distilled water. However, regarding sensitivity to change in pH, the order was DTPA > water > Mehlich-1 > Mehlich-3. The increases in the concentrations of PTE due to the reduction in the pH of the tailings did not lead to concentrations that exceed the limits of Brazilian regulations. The DTPA extractant exhibited higher coefficients of correlation between the PTE concentrations and the pH of the tailings, proving to be suitable for use in areas affected by the deposition of iron mine tailings. [Display omitted]
ISSN:0013-9351
1096-0953
DOI:10.1016/j.envres.2022.114321