title: Remobilization of residual non-aqueous phase liquid in porous media by freeze-thaw cycles.
abstract: The pore-scale behavior of a nonaqueous phase liquid (NAPL) trapped as residual contamination in a porous medium, subject to freeze-thaw cycles, was investigated by X-ray microcomputed tomography. It is shown that freeze-thaw cycles cause significant NAPL remobilization in the direction of the freezing front, due to the rupture and transport of a significant proportion of (supposedly entrapped) larger multipore NAPL ganglia. Significant NAPL remains in place, however, due to substantial ganglion fragmentation into single- and subpore ganglia. The contraction of branched ganglia into more rounded forms, especially near the top surface, is also observed. Three freezing-induced mechanisms are proposed to explain the results. The findings have important implications for NAPL contamination in cold regions, and for the behavior of water-hydrocarbon systems on the Earth and other planets.
authors: School of Engineering and Information Technology, The University of New South Wales at ADFA , Northcott Drive, Canberra, ACT, 2600, Australia.
authors: Kamaljit
authors: K
authors: Singh
authors: Robert K
authors: RK
authors: Niven
authors: Timothy J
authors: TJ
authors: Senden
authors: Michael L
authors: ML
authors: Turner
authors: Adrian P
authors: AP
authors: Sheppard
authors: Jill P
authors: JP
authors: Middleton
authors: Mark A
authors: MA
authors: Knackstedt
mesh_terms: D004784:Environmental Monitoring; D005615:Freezing; D010539:Permeability; D044367:Phase Transition; D016062:Porosity; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000737:chemistry*; D055114:X-Ray Microtomography
chemical_list: D014874:Water Pollutants, Chemical