Phytoremediation
Potentially toxic metals first interact with plants at the roots, where they are taken up by mass flow and diffusion. These metal pollutants are made bioavailable for plants through root secretion of metal-chelating molecules into the surrounding rhizosphere [30], metal reductase in the plasma membrane, and proton extrusion from roots [26]. Several mechanisms of phytoremediation exist [2,9,31,32]. In phytoextraction, soil contaminants are taken up through the roots and accumulate in the shoots [33,34]. In general, higher concentrations of metal in the growth environment result in higher accumulations in plant tissue [35–40]. Then, the contaminated shoot tissues are processed using a variety of disposal methods, such as heat and extraction treatments [41]. For instance, the tissues may be harvested and incinerated as hazardous waste, with the ash being discarded in landfills [42,43], or utilized for the re-extraction of trace elements [44,45]. The harvested biomass can alternatively be used as feedstock for biofuel production or pyrolyzed to form biochar [46–49]. Phytostabilization is a process in which metallic contaminants are immobilized through root adsorption and metal precipitation and stabilized through complex formation or reduction [50]. The immobilization and stabilization of metals to a nontoxic form within the plant prevents interference with cellular metabolism [51]. Phytovolatilization converts potentially toxic metals to more-volatile forms that are removed to the atmosphere through transpiration [44].[1]
- ↑ Placido, D.F.; Lee, C.C. "Potential of Industrial Hemp for Phytoremediation of Heavy Metals." Plants 2022, 11, 595. https://doi.org/10.3390/plants11050595