Horseradish-Mediated Binding of 2,4-Dichlorophenol to Soil

Applying minced horseradish roots enhanced the binding of ¹⁴C-labeled 2,4-dichlorophenol (2,4-DCP) to soil. The presence of peroxides was necessary to activate the oxidation reactions mediated by peroxidases present in the plant tissues. The transformation of 2,4-DCP was completed in 30 min, and the extent of binding depended on the amount of horseradish added to the polluted soil, the concentration and type of peroxide applied as an electron acceptor, and the soil moisture. In reactions with H₂O₂, binding increased from 8 to 50% of the initial radioactivity as the amount of horseradish increased from 0 to 0.5 g per 5 g of soil when the soil was completely saturated with water. The rate of binding was enhanced by a factor of two when calcium peroxide was substituted for hydrogen peroxide. After extraction with water, less than 15% of the initial radioactivity was released from the horseradish-treated soil, compared with 90% released from the untreated control. Most of the radioactivity extracted from treated soil with 0.5 M sodium hydroxide (48%) was associated with humic and fulvic acids (34%). The results obtained provide clear evidence that horseradish treatment of soil polluted with chlorophenols may be an effective means of remediation.