Transport of chlorinated dioxins and furans in soil columns: modeling pentachlorophenol pole-treating oil influence

Column experiments were conducted to validate a screening model predicting the influence of pentachlorophenol (PCP) pole-treating oil on the vertical migration of its impurities, chlorinated dioxins and furans (PCDD/Fs). PCP pole-treating oil (15 mL d(-1)) and water (20 mL d(-1)) were added daily to the top of sand and organic soil columns during 35d. Column soil samples were analyzed to determine concentrations of hydrocarbons and PCDD/Fs at several depths in the columns (0-30cm) and their evolution in time (7, 14, 21 and 35d). The model predicted a significant vertical migration of PCDD/Fs due to the presence of oil as a free phase and PCDD/Fs were found in the different column layers at concentrations consistent with model predictions (same order of magnitude). Measured PCDD/Fs concentrations are in total disagreement with literature data and with model prediction in the absence of oil free phase, which implies PCDD/F properties alone cannot be used to predict their fate in the current context: the influence of PCP pole-treating oil must be accounted for to properly explain their migration.