Sorption of selected polycyclic aromatic hydrocarbons on soils in oil-contaminated systems

The adsorption and desorption behaviour of selected polycyclic aromatic hydrocarbons (PAHs) on different soils was investigated by static and dynamic methods. On the basis of a system including the four phases of soil, water, oil adsorbed and oil in emulsion, a model for the description of the adsorption behaviour in the presence of oil was developed. In systems without oil a similar partitioning behaviour in the batch and column experiments was observed for all PAHs. Thus the distribution coefficients can be calculated from the octanol / water coefficient of the aromatic compounds and the organic carbon content of the soils. The presence of a lipophilic phase had a significant influence on the sorption of the PAHs, usually resulting in a drastic decrease of adsorption with increasing oil content in the system. For the oil-contaminated system the modelling of the adsorption behaviour enabled a more detailed interpretation of the experimental observations as well as the calculation of the sorption behaviour for the PAHs from characteristic parameters of the components involved.