Studies on the Properties of Root Exudates and Their Effects on Solubility of Pentachlorophenol (PCP)

The properties of plant root exudates and their effects on the water solubility of PCP were investigated in this paper. The results showed that the hydrophobic and the high-molecular-weight fractions of sunflower(Helianthus annuus) root exudates were more than those of lucerne(Medicago sativa) root exudates. With time elapsed, the biodegradation rate of lucerne root exudates was higher than sunflower root exudates. The UV adsorption value of root exudates decreased with increasing wavelengths, and the adsorption value of sunflower root exudates were higher than lucerne root exudates. Root exudates may enhance the water solubility of PCP. The solubilization of PCP increased with increasing concentrations of root exudates, and there was excellent linearity between them. The solubilization of sunflower root exudates was stronger than that of lucerne root exudates. Root exudates may enhance water solubility of organic pollutants, because they belong to surface active substance; and the solubilization mechanism was partition effect whose intensity closely correlated with hydrophobic components in the high-molecular-weight fractions of root exudates.