Evaluation of the Capacity of Eleven Plant Species to Accumulate Potential Toxic Elements and Macronutrients in a Lead-Zinc Mining Area for the Purpose of Remediating Contaminated Soils

Abstract

The presence of potential toxic elements (PTEs) in water, soil, and plant resources poses a significant risk to human health. A field investigation on the content of PTEs and macronutrients in soils and 11 dominant plants (roots and shoots) from Ahangaran, a Pb–Zn mine in western Iran was carried out. The bioconcentration factors (BCF) for roots and shoots (BCF root, BCF shoot) based on both total and available PTEs and macronutrients in soils and translocation factors (TF) of 11 plant species were calculated. The average contents of total soil Cd, Cu, Ni, Pb, and Zn were 198, 124, 86, 38, and 5 times higher than their corresponding background values, respectively. The high and variable contents of P, K, Ca, and Mg, with lower Na, were observed across the plant species. Potential toxic elements like Pb, and Zn have high mobility indices in the soils, meaning these PTEs are more likely to be taken up by plants, potentially causing toxicity. Simultaneous presence of elevated levels of Pb, Fe, and Cd characterizes the contamination profile of the plants at the study locations. When various BCF values based on available PTEs in soils were taken into account, Stachys inflata and Senecio gallicus consistently function as effective phytostabilizers, exhibiting higher root accumulation than shoot accumulation and TF below 1 for all PTEs except Stachys inflata for Zn, making them the most reliable candidates for PTEs retention in roots. Conversely, Phlomis olivieri, Euphorbia szovitsii, and particularly Achillea millefolium consistently perform as phytoextractors across all six PTEs, displaying TF above 1 and high shoot bioconcentration factors, with Achillea millefolium showing exceptional TF (up to 3.03 for Fe). The native plant species identified in this study offer practical applicability for large-scale phytoremediation in similar semi-arid mining environments, enabling evidence-based selection of stabilizers for long-term PTEs containment and accumulators for active PTEs removal.