The impact of fullerene soot (FS), single-walled (SWCNTs) and multi-walled (MWCNTs) carbon nano-tubes on the behaviour of two C-14-PAHs in sterile soil was investigated. Different concentrations of carbon nanomaterials (0, 0.05, 0.1 and 0.5%) were added to soil, and C-14-phenanthrene and C-14-benzo[a] pyrene extractability assessed over 80 d through dichloromethane (DCM) and hydroxypropyl-beta-cyclo-dextrin (HPCD) shake extractions. Total C-14-PAH activity in soils was determined by combustion, and mineralisation of C-14-phenanthrene was monitored over 14 d, using a catabolically active pseudomonad inoculum. No significant loss of C-14-PAH-associated activity from CNM-amended soils was observed over the 'aging' period. CNMs had a significant impact on HPCD-extractability of C-14-PANS: extractability decreased with increasing CNM concentration. Additionally, C-14-phenanthrene mineralisation was inhibited by the presence of CNMs at concentrations of >= 0.05%. Differences in overall extents of C-14-mineralisation were also apparent between CNM types. It is suggested the addition of CNMs to soil can reduce PAH extractability and bioaccessibility, with PAH sorption to CNMs influenced by CNM type and concentration. (C) 2010 Elsevier Ltd. All rights reserved.