phytoextraction

Phytoextraction, also known as phytoaccumulation, is a subset of phytoremediation in which plants remove contaminants from soil or water by absorbing them through the roots and concentrating them in harvestable tissues. The process relies on plant uptake, translocation to shoots via the xylem, and sequestration within leaves and stems. After plants mature, the biomass is harvested and disposed of or processed to recover the metals, thereby reducing the total contaminant mass in the environment.

Hyperaccumulator species, such as certain Brassicaceae, can accumulate unusually high concentrations of metals, enabling practical remediation, especially for low-to-moderate contamination. Common targets include cadmium, zinc, nickel, and copper, with zinc and cadmium often studied together.

Effectiveness depends on many factors: soil pH, organic matter, metal speciation, climate, plant species and growth rate, and agronomic practices. Some approaches use chelating agents (for example EDTA) to increase metal bioavailability and uptake, but this can raise the risk of leaching and groundwater contamination. Beneficial soil microbes and plant breeding or genetic engineering are also explored to improve uptake and tolerance.

Applications include remediation of contaminated industrial sites, mining-impacted lands, and urban soils. Phytoextraction is generally slow and best suited to shallow, moderately contaminated sites with sufficient plant biomass. It is often combined with other remediation strategies and requires safe handling and disposal of contaminated plant material, sometimes with metal recovery via phytomining.