Assessing the bioavailability of PAHs in field-contaminated sediment using XAD-2 assisted desorption.

An XAD-2 assisted desorption assay was evaluated to assess its functionality in determining the bioavailability of polycyclic aromatic hydrocarbons (PAHs) in an aged field-contaminated sediment. In the study, various dosages of XAD-2 resin were added to abiotic sediment-water slurry systems to adsorb the PAHs from the aqueous phase thus accelerating the desorbability of these contaminants from the sediment. A parallel experiment on the biodegradation of these PAHs by microorganisms indigenous to the sediment was also conducted. Both the desorbability of the PAHs in the XAD-2 assisted desorption assay and their biodegradability decreased with time and eventually approached constant values. The two procedures showed very similar residual concentrations of PAHs for compounds with less than five benzene rings. This suggests that the XAD-2 assisted desorption assay shows promise in measuring the bioavailability of PAHs in field-contaminated sediments and could be used for predicting the end point of PAH bioremediation.