*2.3.3 Phytostabilization*

Phytostabilization aims to contain contaminants within the vadose zone through accumulation by roots or precipitation within the rhizosphere. As a result of phytostabilization, heavy metals concentrations in contaminated soil are not reduced, but their movement is prevented [49]. When phytoextraction is not feasible or desirable, phytostabilization is used. In addition, phytostabilization can be used at sites with technical or regulatory limitations that make the selection and implementation of more appropriate remediation techniques difficult [50]. In abandoned contaminated sites such as mine wastelands, urban landfills, and sewage treatment plants, phytostabilization is commonly used. In tailings areas, pioneer plants are typically used to enhance physicochemical properties, provide cover, and establish a vegetation cap for long-term stability [51]. To maintain optimal stabilizing conditions, the site must be monitored regularly since heavy metals are stabilized within soil. A hyperaccumulator plant with the best phytostabilization properties (a) reduces heavy metals leaching by reducing water percolation through the soil matrix, (b) inhibits soil erosion and moves heavy metals to other areas, and (c) prevents direct contact with soil contaminated with heavy metals [52]. The most commonly used plant species for phytostabilization of Pb, Zn, and Cu polluted soils in Europe are Festuca spp. and Agrostis spp. [53].
