Influence of heavy organic pollutants of anthropic origin on PAH retention by kaolinite.

The adsorption of heavy fuel oil No. 2 (F2) on a reference kaolinite (Arvor kaolin, France), and the influence of this anthropic organic matter on the phenanthrene (PHEN) retention capacity of a kaolinite were investigated in the laboratory. The heaviest and most polar compounds of F2 are adsorbed on kaolinite preferentially to the other compounds and also partly irreversibly. The precoating of kaolinite by F2 significantly increases the sorption of PHEN in the range of concentrations studied (10-500 microg l(-1)). The partition coefficients normalized to organic carbon content (Koc) of kaolin precoated with fuel oil (5.2 < log Koc < 5.5) are one order of magnitude higher than those of the original kaolin (4.2 < logKoc < 4.5), and show very good agreement with the literature for polluted industrial soils. The Koc measured on the uncoated kaolin are in close agreement with the values determined for natural soils in which humic substances represent the organic component. This demonstrates that the composition of organic matter is the primary factor in PHEN retention by the soils. Therefore, in predicting the transport of PHEN, and other Polycyclic aromatic hydrocarbons (PAHs) in general, in soils of industrial sites containing heavy hydrocarbons or tars requires that the specific nature of the organic matter contained in these soils be taken into consideration.