Remobilization of residual non-aqueous phase liquid in porous media by freeze-thaw cycles.
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.
Duke Scholars
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Related Subject Headings
- X-Ray Microtomography
- Water Pollutants, Chemical
- Porosity
- Phase Transition
- Permeability
- Freezing
- Environmental Sciences
- Environmental Monitoring
Citation
Published In
DOI
EISSN
Publication Date
Volume
Issue
Start / End Page
Location
Related Subject Headings
- X-Ray Microtomography
- Water Pollutants, Chemical
- Porosity
- Phase Transition
- Permeability
- Freezing
- Environmental Sciences
- Environmental Monitoring