Iron hazard in an impacted estuary: Contrasting controls of plants and implications to phytoremediation

• Published in: Journal of hazardous materials Vol. 428; p. 128216
• Main Authors: Ferreira, Amanda Duim, Queiroz, Hermano Melo, Otero, Xosé Luis, Barcellos, Diego, Bernardino, Ângelo Fraga, Ferreira, Tiago Osório
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 15-04-2022
• Subjects: Biodegradation, Environmental; Biogeochemistry; Estuaries; H. tiliaceus; Iron; Mine tailings; Phytoextraction; Plant Roots - chemistry; Soil; Soil Pollutants - analysis; T. domingensis; Typhaceae; Wetlands; T. domingensis; H. tiliaceus; Mine tailings; Biogeochemistry; Phytoextraction
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2022.128216

Due to its abundance and role as a micronutrient for plants iron (Fe) is rarely perceived as a contaminant. However, in redox active environments, Fe bioavailability increases sharply representing an environmental risk. In this study, a recent catastrophic mining dam failure is used as a field framework to evaluate the role of wetland plants on Fe biogeochemistry and assess their potential for phytoremediation programs. To achieve these objectives, a Fe geochemical partitioning and the concentration of Fe in different plant compartments (iron plaque on root surfaces, roots, and leaves) were determined in two sites vegetated by different wetland species. Soils exhibited contrasting Fe biogeochemical dynamics. Lower pseudo-total contents and more reactive Fe oxides were observed in the soil vegetated by Typha domingensis. Iron plaque was present on both species but more concentrated in Fe in T. domingensis. T. domingensis showed Fe shoot concentrations (3874 mg kg−1) 10-fold higher than in Hibiscus tiliaceus, which prevented Fe absorption through iron plaque formation and root accumulation. In conclusion, contrasting biogeochemical effects on Fe (e.g., rhizosphere acidification) lead to different phytoremediation abilities. T. domingensis showed a high potential for Fe phytoremediation on sites affected by Fe-enriched wastes and should be tested in assisted phytoremediation approaches.
[Display omitted]
•Redox conditions and roots acidification drives Fe accumulation in T. domingensis.•Fe plaque have opposite effects on Fe absorption for T. domingensis and H. tiliaceus.•Unmanaged T. domingensis showed the potential to concentrate > 3500 mg kg−1 of Fe.•T. domingensis should be tested in assisted phytoremediation programs.