Advances in phytoremediation

Phytoremediation is the use of plants to remedy contaminated soils, sedimen ts, and/or groundwater. Sorption and uptake are governed by physicochemical properties of the compounds, and moderately hydrophobic chemicals (logarit hm octanol-water coefficients = 1.0-3.5) are most likely to be bioavailable to rooted, vascular plants. Some hydrophilic compounds, such as methyl-ter t-butylether and 1,4-dioxane, may also be taken up by plants via hydrogen b onding with transpiration water. Organic chemicals that pass through membra nes and are translocated to stem and leaf tissues may be converted (e.g., o xidized by cytochrome P450s), conjugated by glutathione or amino acids, and compartmentalized in plant tissues as bound residue. The relationship betw een metabolism of organic xenabiotics and toxicity to plant tissues is not well understood. A series of chlorinated ethenes is more toxic to hybrid po plar trees (Populus deltoides x nigra, DN-34) than are the corresponding ch lorinated ethanes. Toxicity correlates best with the number of chlorine ato ms in each homologous series. Transgenic plants have been engineered to rap idly detoxify and transform such xenobiotic chemicals. These could be used in phytoremediation applications ii issues of cost and public acceptability are overcome.