The potential environmental implications of buckminsterfullerene (C60) and its derivatives have received much attention. In this study, we investigated facilitated transport of 2,2',5,5'-polychlorinated biphenyl (PCB) and phenanthrene by nC60 (a stable aqueous-phase aggregate of C60) through two sandy soil columns. We found that low-level (from 1.55 to 12.8 mg/L) nC60 could significantly enhance the mobility of PCB and phenanthrene. However, none of the three model dissolved organic matters (DOMs)-a humic acid, a fulvic acid, and a bovine serum albumin-had a noticeable effect on the transport of PCB when these DOMs were present at concentrations equivalent to approximately 10-11 mg/L organic carbon. We propose that the contaminant-mobilizing ability of nC60 is a result of irreversible adsorption of a fraction of nC60-associated PCB/phenanthrene (whereas DOM-associated PCB is readily desorbable). Additionally, slow desorption kinetics of nC60-adsorbed PCB/phenanthrene is another possible mechanism. The findings in this study indicate that nC60 in the subsurface environment can greatly enhance the mobility of nonionic, highly hydrophobic organic contaminants, which typically exhibit very low mobility. Such effects should be taken into account when assessing the potential environmental risks of engineered carbonaceous nanomaterials.