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<p>The collapse of the Fundão tailings dam in 2015 triggered widespread contamination across the Doce River basin, yet its long-term effects on lacustrine environments remain poorly understood. This study investigates how sediment mineralogy influences the retention and mobility of potentially toxic elements (PTEs) in shallow and deep lakes of the Lower Doce River. Between 2018 and 2019, bottom sediment samples (0–5&#xa0;cm) were collected from three deep lakes (Limão, Nova, and Juparanã) and three shallow lakes (Areão, Areal, and Monsarás). Twenty-four sediment samples were analyzed for mineralogy (X-ray diffraction and Fourier-transform infrared spectroscopy) and PTE concentrations using sequential extraction followed by ICP-MS/MS. PTEs were fractionated through a six-step sequential chemical extraction designed to isolate soluble/exchangeable, carbonate-bound, Fe oxide-bound (including poorly crystalline and crystalline phases), and pyrite-associated fractions. The results show that goethite and hematite are the main Fe oxyhydroxides in lake sediments, suggesting the legacy of deposited tailings. Deep lakes contain well-crystallized, Al-substituted goethites that enhance the retention of As, Cr, and V in more stable geochemical fractions. In contrast, shallow lakes, especially Areal and Monsarás, exhibit slightly higher hematite content and goethites with lower Al substitution and specific surface area, indicating reduced stability and greater susceptibility to redox-driven dissolution. Additionally, PTEs such as Co, Cu, Ni, Pb, and Zn are primarily associated with poorly crystalline Fe phases like ferrihydrite and lepidocrocite, which are prone to dissolution under anoxic conditions. Risk assessments indicate higher carcinogenic risks from As, Cr, and Ni exposure in shallow lakes, especially for children.</p>

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Mineralogical insights into the potentially toxic elements and health risks in lacustrine environments in the Lower Doce River, Southeastern Brazil

  • 期刊论文

  • 发表日期：

    2025年8月24日

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  • David Lukas de Arruda,
  • Luiz Aníbal da Silva Filho,
  • Sara Ramos dos Santos,
  • Gilberto Fonseca Barroso,
  • Marcelo Metri Corrêa,
  • Paulo Jorge Sanches Barbeira,
  • Danniel Brandão Mendes,
  • Vânya Márcia Duarte Pasa,
  • Danilo de Lima Camêlo

摘要

The collapse of the Fundão tailings dam in 2015 triggered widespread contamination across the Doce River basin, yet its long-term effects on lacustrine environments remain poorly understood. This study investigates how sediment mineralogy influences the retention and mobility of potentially toxic elements (PTEs) in shallow and deep lakes of the Lower Doce River. Between 2018 and 2019, bottom sediment samples (0–5 cm) were collected from three deep lakes (Limão, Nova, and Juparanã) and three shallow lakes (Areão, Areal, and Monsarás). Twenty-four sediment samples were analyzed for mineralogy (X-ray diffraction and Fourier-transform infrared spectroscopy) and PTE concentrations using sequential extraction followed by ICP-MS/MS. PTEs were fractionated through a six-step sequential chemical extraction designed to isolate soluble/exchangeable, carbonate-bound, Fe oxide-bound (including poorly crystalline and crystalline phases), and pyrite-associated fractions. The results show that goethite and hematite are the main Fe oxyhydroxides in lake sediments, suggesting the legacy of deposited tailings. Deep lakes contain well-crystallized, Al-substituted goethites that enhance the retention of As, Cr, and V in more stable geochemical fractions. In contrast, shallow lakes, especially Areal and Monsarás, exhibit slightly higher hematite content and goethites with lower Al substitution and specific surface area, indicating reduced stability and greater susceptibility to redox-driven dissolution. Additionally, PTEs such as Co, Cu, Ni, Pb, and Zn are primarily associated with poorly crystalline Fe phases like ferrihydrite and lepidocrocite, which are prone to dissolution under anoxic conditions. Risk assessments indicate higher carcinogenic risks from As, Cr, and Ni exposure in shallow lakes, especially for children.