Remobilization of Residual Non-Aqueous Phase Liquid in Porous Media by Freeze - Thaw Cycles
Date
2011
Authors
Singh, Kamaljit
Niven, Robert
Senden, Timothy
Turner, Michael
Sheppard, Adrian
Middleton, Jill
Knackstedt, Mark
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American Chemical Society
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.
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Keywords
Keywords: Cold regions; Freeze-thaw cycles; Hydrocarbon systems; Microcomputed tomography; NAPL contamination; Nonaqueous phase liquids; Porous Media; Porous medium; Remobilization; Top surface; Computerized tomography; Freezing; Hydrocarbons; Liquids; Porous mater
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Source
Environmental Science and Technology
Type
Journal article
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2037-12-31
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