Capacidade fitorremediadora para Fe da espécie cordia superba em rejeito proveniente da mineração de ferro

Abstract

With the advancement of mining activities, the need for effective techniques for environmental recovery of degraded areas grows, ensuring ecological restoration and preservation of natural resources. Phytoremediation, therefore, is an economically viable technique for recovering degraded areas using plant species as a tool for remediation. This study aimed to evaluate the phytoremediation potential of the species Cordia superba (babosa branca) in soils contaminated with iron mining waste from the Quadrilátero Ferrífero in Minas Gerais, Brazil. The research involved four experimental groups with different proportions of material from iron mining waste: 0% (control), 25%, 50%, and 100%. Seedlings of the Cordia superba species were maintained under controlled conditions for seventy days. Soil analyses determined pH, conductivity, moisture, NPK, and iron content, while plant analyses assessed biomass, iron content in plant tissues, and physiomorphological parameters (height and stem diameter, main root length, number of living leaves, and number of secondary roots). Additionally, bioconcentration factors (BCF) and translocation factors (TF) for iron were calculated based on the iron content in plant tissues. The results indicated an increase in iron concentrations proportional to the amount of waste in the soil. Cordia superba showed good development in Groups A (control) and B (25%) with mild signs of iron-induced stress, demonstrating tolerance to the contaminant. In Groups C (50%) and D (100%), the species exhibited a reduction in total biomass and morphological changes, such as spots and leaf deformations, typical of iron toxicity. However, the species maintained basic physiological functionality, suggesting adaptive resistance. The BCF indicated greater accumulation of iron in the roots, with an índex above 1 in Groups A, B, and C, while the TF showed values above 1 in Groups B and D. This suggests that Group B not only accumulated iron in the roots but also translocated it to the aerial parts, while Group D hyperaccumulated iron only in the leaves. In this context, the results highlight the promising potential of Cordia superba as an efficient species for phytoremediation of soils degraded by iron mining waste. At 25% waste, it is considered a Fe phytoextractor; at 50% waste, it is classified as a Fe phytostabilizer; and at 100% waste, it serves as a good Fe hyperaccumulator in leaves. This versatility, adapting to different Fe concentrations with distinct phytoremediation mechanisms, is noteworthy. Cordia superba, therefore, offers a viable, sustainable, and low-cost alternative for environmental recovery.