Florencia González

Phytoextraction is a sustainable strategy for removing potentially valuable elements from contaminated substrates while contributing to site remediation. However, the effectiveness of repeated phytoextractive cycles remains poorly investigated. This study evaluated the phytoextraction performance of Helianthus annuus (HA) cultivated on mining soil from Complejo Minero Fabril Sierra Pintada (Argentina) containing elevated concentrations of Ni, Zn, Sr, P, and Cu over three successive three-month cultivation cycles in TRL-4 bioreactors (BRs). The scalability of the process was subsequently assessed through projection to TRL 6 using a Vegetable Depuration Module (VDM). Elemental concentrations in soil and biomass were determined by X-ray fluorescence, while bioaccumulation coefficients, translocation factors, arbuscular mycorrhizal colonization and glomalin-related soil proteins (GRSP) were assessed to identify biological factors associated with phytoextraction performance. Projected bioextractive potential at TRL 6 (VDM) during the first cycle reached 16.15 ± 2.40 g Cu, 20.81 ± 2.19 g Zn, 7.43 ± 1.15 g Ni, 11.39 ± 1.19 g Sr, and 126.87 ± 15.42 g P. Phytoextractive efficiency declined substantially after the first cultivation cycle, indicating that a single crop harvested at the flowering stage maximized element removal under the tested conditions. The accumulation of economically relevant elements in sunflower biomass could be integrated with downstream metal recovery processes, highlighting the potential of HA for phytomining applications.

Phytoextraction is a sustainable strategy for removing potentially valuable elements from contaminated substrates while contributing to site remediation. However, the effectiveness of repeated phytoextractive cycles remains poorly investigated. This study evaluated the phytoextractive performance of Helianthus annuus (HA) cultivated on mining soil from Complejo Minero Fabril Sierra Pintada (Argentina) containing elevated concentrations of Ni, Zn, Sr, P, and Cu over three successive three-month cultivation cycles in TRL-4 bioreactors (BRs). The scalability of process was subsequently assessed throught projection to TRL 6 using a Vegetable Depuration Module (VDM). Elemental concentrations in soil and biomass were determined by X-ray fluorescence, while bioaccumulation coefficients, translocation factors, arbuscular mycorrhizal colonization, and glomalin-related soil proteins (GRSP) were assessed. Projected bioextractive potential in the TRL6 (VDM) during the first cycle reached 3.16 g Cu, 10.82 g Zn, 1.13 g Ni, 13.36 g Sr, and 136.91 g P. Phytoextractive efficiency declined markedly after the first cultivation cycle, indicat-ing that a single crop harvested at the flowering stage maximized element removal under the tested conditions. The accumulation of economically relevant elements in sunflower biomass could be integrated with downstream metal recovery processes, supporting the potential of HA for phytomining applications.

Mining activities cause strong soil alterations, such as heavy metal (HM) pollution, which decreases the diversity of plant communities and rhizospheric microorganisms, including arbuscular mycorrhizal (AM) fungi. The polymetallic Paramillos de Uspallata mine in the Andes Mountains, the first mining exploitation in Argentina, provides a unique scenario to study AM fungal resilience after long-term disturbance following over 40 years of inactivity. This study aimed to analyze mycorrhizal status and AM fungal communities in the mine and a nearby unexploited area and to evaluate their associations with soil parameters to elucidate life history strategies. Long-term exposure to elevated Fe, Pb, Zn, and Ag concentrations and high electrical conductivity (EC, 5.46 mS/cm) led to the dominance of Entrophospora infrequens in association with Pappostipa speciosa, demonstrating that this AM species is a stress-tolerant strategist in symbiosis with a pioneer perennial plant, resilient in the most impacted mine areas. In contrast, the unexploited area, with an EC of 0.48 mS/cm and low HM contents, supported competitive and ruderal species, revealing distinct ecological strategies of AM fungi in disturbed versus undisturbed environments. These findings highlight the potential of E. infrequens for bioremediation and ecological restoration in post-mining landscapes.