Abstract
The assessment of risks and remediation of oil sands process-affected water (OSPW) requires an understanding of possible interactions of naturally occurring surfactants with hydrophobic organic compounds, such as polycyclic aromatic hydrocarbons (PAHs). In this study, effects of the extractable organic fraction of OSPW (OF-OSPW) on rates of release and freely dissolved aqueous concentration of several PAHs were investigated using a passive dosing approach, in which a poly(dimethylsiloxane) (PDMS) film was loaded with PAHs of interest. The concentrations of PAHs released from PDMS into aqueous solutions were directly proportional to concentrations of OF-OSPW. PAHs reached equilibrium partitioning 1-4 h faster when the aqueous phase was OF-OSPW than when it was freshwater. Greater concentrations of PAHs were released from PDMS when OF-OSPW was reconstituted in saline water compared to when it was reconstituted in freshwater. Apparent aqueous solubilities of PAHs were greater in intact OSPW than in OF-OSPW. Measured concentrations of PAHs in various aqueous solutions of OSPW and salts correlated with log K-ow of PAHs. This might be because of disruption of PAHs sorbed into PDMS. These results suggest that the bioavailability of PAHs can be greater in the presence of more polar organic compounds in OSPW.