Effect of EDTA and Zero-Valent Iron Nanoparticles on Phytoremediation Capacity of Cistanthe grandiflora

Mining activities in Chile generate massive amounts of tailings, creating significant environmental risks due to heavy metal contamination. Phytoremediation offers an eco-friendly solution, yet studies on native Chilean species are scarce. This study evaluates the effects of ethylenediamine tetraacetic acid (EDTA) and nanoscale zero-valent iron (nZVI) on the potential of the native Cistanthe grandiflora for the phytoremediation of copper mine tailings. A six-month pot experiment was conducted with four treatments: EDTA 300 mg·kg⁻¹, EDTA 600 mg·kg⁻¹, nZVI 500 mg·kg⁻¹, and a control group without additions. The results indicate that Cistanthe grandiflora primarily acts as a phytostabilizer, accumulating higher metal concentrations in roots than in aerial parts. The application of EDTA significantly enhanced the Bioconcentration Factor for Cu, Ni, Pb, and Mo, increasing BCF values from 0.5 to 1.0 or more in several cases. Specifically, a lower dose of EDTA (300 mg·kg⁻¹) successfully increased the Translocation Factor (TF) of cadmium to 1.3, suggesting a potential for phytoextraction for this element. Conversely, nZVI application showed a limited impact, slightly improving the Translocation factor for copper and chromium but without exceeding unity. These findings demonstrate that Cistanthe grandiflora, assisted by EDTA, is a promising candidate for the phytostabilization of heavy metals in mine tailings.