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Environmental risk assessment following Brazilian mining dam collapse: A diffusion approach
Leticia A Bertoldo1, Barbara Kroetz1, Cecilia S Dos Reis1
1Department of Chemistry, State University of Londrina, Londrina, Paraná, Brazil.
Chemosphere
|March 22, 2026
Summary
Iron-ore sludge from the 2015 dam collapse in Brazil migrates into soil, posing environmental risks. This study quanties the diffusion of toxic elements like lead and arsenic, crucial for assessing soil contamination.
Area of Science:
- Environmental Science
- Geochemistry
- Soil Science
Background:
- The 2015 Doce River Basin (DRB) dam collapse released iron-ore sludge, impacting the environment.
- Limited research exists on sludge-soil interaction and the diffusion of potentially toxic elements (PTE).
Purpose of the Study:
- To investigate the impact of iron-ore sludge on PTE mobility in soil.
- To quantify the diffusion coefficients of PTE in soil following the DRB dam collapse.
- To evaluate the long-term environmental risks of sludge contamination in soil ecosystems.
Main Methods:
- Soil samples were subjected to diffusion tests using the planar-source method over 7 days.
- Sludge was used as the PTE source (head).
- Diffusion coefficients for Pb, Ni, Cr, and As were determined.
- Diffusion profiles were analyzed using one-diffusion and double Gaussian models.
Main Results:
- Diffusion coefficients for Pb, Ni, Cr, and As were approximately 10-12 m2 s-1, indicating potential sludge-soil migration.
- Ni and Pb diffusion followed a one-diffusion profile, while As and Cr exhibited a double Gaussian diffusion profile.
- 3D-surface tests enabled projection of contamination fronts on long-term scales.
Conclusions:
- Sludge diffusion in soil is a significant pathway for PTE contamination.
- Environmental risk assessments must incorporate diffusion parameters for accurate evaluation.
- This study provides crucial data on PTE diffusion in DRB soils, aiding mitigation strategies.
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