ISSN:
1745-6584
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Energy, Environment Protection, Nuclear Power Engineering
,
Geosciences
Notes:
Dense nonaqueous phase liquids (DNAPLs) such as perchloroethylene, polychlorinated biphenyls, creosote mixtures, and many solvents and degreasers can be released into karst aquifers through sinkholes and sinking streams in quantities up to tanker car volumes. Although DNAPLs are easily injected into karst aquifers, discharge of the contaminants through springs may be significantly delayed depending on transport mechanism, storm water recharge, and storage sites within the karst aquifer. Storage sites include (1) the epikarst; (2) pools and depressions within underground streams; (3) incorporation of DNAPL within clastic sediments that are present in most conduits; (4) adsorption onto organic materials and onto manganese oxides, iron oxides, and other substrates; and (5) migration to depth within the fracture system. Effective transport of DNAPL contaminants during storm flow pulses requires the exceedance of thresholds best defined in terms of the conduit stream power. Movement of pooled DNAPL requires a boundary shear between the liquid and water flowing over it. DNAPL stored in clastic sediment bleeds out slowly or dissolves into surrounding pore water until storm pulses create a stream flow sufficient to flush the pore water, or possibly move the sediment pile itself. Under extreme flow conditions the entire sediment pile, including the DNAPL, can be entrained and ejected from the conduit system.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1745-6584.2001.tb00357.x
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