Induced Phytoextraction of Mercury

ABSTRACT Extraction of hazardous compounds by plants (phytoextraction) is considered a green technology for the remediation of soils and water bodies. Phytoextraction of mercury is very challenging due to the specific chemical/biochemical properties of this element and its low plant uptake. In this review, mechanisms and processes of enhancing phytoextraction of mercury are summarized. Plants that look promising for induced phytoextraction of mercury are described. Additives of various types that may significantly increase the efficiency of mercury phytoextraction are critically evaluated. Thiosulfates and other sulfur-containing compounds, aminopolycarboxylic acids, low-molecular-weight organic acids and enzymes are considered in detail. The important role of selective chemical inductors, primarily thiosulfates, is demonstrated. It is shown that synthetic aminopolycarboxylic acids have the potential for increasing bioavailability of mercury in soils and its translocation to above-ground organs of plants-phytoextractors. Non-chemical methods of inducing mercury phytoextraction are also addressed. Abbreviations: APCA: aminopolycarboxylic acid, BAF: bioaccumulation factor, BDL: below detection limit Cys: cysteine, DTPA: diethylenetriaminepentaacetic acid, DW: dry weight, EDDHA: ethylenediamine-N,N′-bis(2-hydroxyphenylacetic) acid, HEDTA: hydroxyethylethylenediaminetriacetic acid, IPEN: International Pollutants Elimination Network (https://ipen.org/), LMWOA: low-molecular-weight organic acid, MPC: below maximum permission concentration, ND: not detectable, NTA: nitrilotriacetic acid, PGPR: plant growth-promoting rhizobacteria, TF: translocation factor