Sublethal effects of mining tailings on Folsomia candida: Insights from oxidative stress and damage biomarkers

This study investigated whether Brumadinho mining tailings still induce sublethal oxidative stress and oxidative damage in Folsomia candida three years after the dam collapse. Springtails were exposed for 10 days to control soil or to 25, 50, 75, and 100% tailings, and antioxidant system, (superoxide dismutase - SOD, catalase - CAT, reduced glutathione - GSH, metallothionein - MT, and total antioxidant capacity - TAC and oxidative damage (lipid peroxide in the form of malondialdehyde - MDA and protein carbonylation - PC. Exposure the tailings induced responses varied among treatments, with observed modulation of SOD (69% inhibition and 552% induction at 25% and 75%, respectively), CAT (increases at 25% and 75% and reductions at 50% and 100%), and a significant reduction of 21% and 25% in GSH at 25-50% tailings exposure, respectively. Metallothionein increased significantly by 531% and 557% at 75% and 100% compared to the control. Increased TAC levels were observed at 75%, reaching 0.7133 mmol L^-1 g ptn^-1, indicating intensification of defense responses associated with increasing tailings concentrations. An increasing MDA trend at 75-100% tailings concentrations (p = 0.0923) was observed, while PC increased significantly from 115% compared to the control at 50%. Biomarker integration using the IBRv2 method indicated that the 75% tailings treatment elicited the highest integrated response among the tested conditions. Overall, exposure to Brumadinho tailings collected three years after the dam collapse altered redox-related biomarkers and induced oxidative damage in F. candida, highlighting the usefulness of biomarkers and integrative indices for detecting sublethal effects in mining-impacted soils.