phytostabilisation

Phytostabilisation is a remediation approach within phytoremediation that uses plants to immobilize contaminants in soils, sediments, or water, thereby reducing their mobility and bioavailability. In this strategy, plants establish a root system that stabilizes contaminants through sequestration in roots, adsorption to root surfaces, precipitation, and interactions in the rhizosphere, while limiting uptake and translocation to shoots. This in-situ method aims to lower exposure to humans and wildlife and to reduce erosion and leaching from contaminated sites without removing the pollutants.

Mechanisms include root-mediated immobilization, complexation with organic acids, formation of insoluble metal compounds, and changes in soil physics and chemistry that favor retention of contaminants. Rhizosphere microorganisms can also contribute to immobilization. Phytostabilisation is commonly applied to inorganic contaminants such as heavy metals (lead, arsenic, cadmium, mercury), metalloids, and some radionuclides, at mining tailings, smelter sites, brownfields, and other contaminated soils or sediments. It is generally not suitable for volatile organic compounds or substances that require extraction.

Effective implementation relies on selecting plant species with high tolerance to contaminants, strong root systems, and limited translocation to shoots. Willows (Salix spp.), poplars (Populus spp.), and certain grasses are frequently used. Management may include soil amendments to adjust pH or organic matter to reduce solubility and enhance stabilization, and, when necessary, mycorrhizal associations.

Advantages include low cost, in-situ treatment, and preservation of site structure and habitat. Limitations involve long time frames, dependence on stable site conditions, possible remobilization if pH or redox conditions change, and the need to manage contaminated biomass after harvest. Evaluation uses indicators such as root concentration factors, translocation factors, and measurements of soil bioavailability and contaminant mass balance.