Advances in phytoremediation.

Abstract

Phytoremediation is the use of plants to remedy contaminated soils, sediments, and/or groundwater. Sorption and uptake are governed by physicochemical properties of the compounds, and moderately hydrophobic chemicals (logarithm octanol--water coefficients = 1.0--3.5) are most likely to be bioavailable to rooted, vascular plants. Some hydrophilic compounds, such as methyl-tert-butylether and 1,4-dioxane, may also be taken up by plants via hydrogen bonding with transpiration water. Organic chemicals that pass through membranes and are translocated to stem and leaf tissues may be converted (e.g., oxidized by cytochrome P450s), conjugated by glutathione or amino acids, and compartmentalized in plant tissues as bound residue. The relationship between metabolism of organic xenobiotics and toxicity to plant tissues is not well understood. A series of chlorinated ethenes is more toxic to hybrid poplar trees (Populus deltoides x nigra, DN-34) than are the corresponding chlorinated ethanes. Toxicity correlates best with the number of chlorine atoms in each homologous series. Transgenic plants have been engineered to rapidly detoxify and transform such xenobiotic chemicals. These could be used in phytoremediation applications if issues of cost and public acceptability are overcome.

Removal of pharmaceuticals and personal care products from wastewater using algae-based technologies: a review

“…Xenobiotics with -COOH, -OH or -NH 2 in their structures and metabolites from phase-I can be conjugated with glutathione (GSH) or glucuronic acid catalyzed by glutathione S-transferases (GSTs) or glucosyltransferases (Nakajima et al 2007;Pflugmacher et al 1999;Yang et al 2002). Phase-III involves compartmentation of xenobiotics in vacuoles or cell wall fractions (Dietz and Schnoor 2001;Petroutsos et al 2008). The ability of algae to detoxicate xenobiotics is similar to that of mammalian liver and thus algae are considered as ''green livers'' for the detoxification of environmental contaminants (Torres et al 2008).…”

Constructed wetlands with light expanded clay aggregates for agricultural wastewater treatment

“…Due to the moderate lipophilicity of MCPA, as expressed by its octanol-water partition coefficient (log K ow = 1.37-1.43 (Montgomery, 1993)), it is likely that plants have an active role in the removal of this compound through direct uptake. In fact, it is widely considered that organic compounds with 0.5 b log K ow b 3 have adequate properties to move through cell membranes and enter the plant's transpiration stream, thereby being easily taken up by the plants (Dietz and Schnoor, 2001;Pilon-Smits, 2005).…”

Efficiency of Rye Biomass on Oil Hydrocarbon Biodegradation

“…Many of the plant xenobiotic enzymes are constitutive, unlike microbial enzymes, which are inductive, requiring prior induction for action, since extensive metabolism of numerous xenobiotics was observed in plant cell cultures without any prior induction treatment [4]. Thus plants as tools of bioremediation of contaminants have gained importance.…”

“…There are numerous mechanisms by which plants may remediate contaminated sites. Many plant enzymes appear to play an important role in xenobiotic degradation, including dehydrogenases, peroxidases, nitroreductases, dehalogenases and others mono-and dioxygenases [4,11,15]. The majority of these plants secrete their enzymes in the soil, where they can decompose various organic compounds.…”