Migration in Soil and Natural Attenuation of Two Hydrocarbons from the Diesel Fraction

To evaluate the risk of transport of two hydrocarbons (HC) from the soil of a former oil refinery to the groundwater, samples from soil profiles were characterized, natural attenuation was evaluated experimentally, and vertical transport was simulated. Due to the important adsorption and consequent low bioavailability, less than 20% of PHE and HXD were degraded within three months, either under aerobic or anoxic conditions. Oxygen and nutrients were not the limiting factors for the degradation of PHE and HXD. According to the results of the one–dimensional reactive transport modeling, the investigated HC would only be transported a few tenths of meters in the subsurface of the contaminated soil. Hence, these HC will probably not reach the groundwater table and will therefore not cause contamination of the principal aquifer. Nevertheless, highly soluble substances, or transport through fractures, can endanger the aquifer, and therefore monitoring of the groundwater is therefore highly recommended.