title: Kinetic control of contaminant release from NAPLs--experimental evidence.
abstract: Mass transfer processes of pollutants from non-aqueous phase liquids (NAPL) may control groundwater pollution at abandoned industrial sites. We studied release kinetics of polycyclic aromatic hydrocarbons (PAHs) from fresh and aged tar phases using a dialysis tubing technique. Time for equilibration ranged from several days to more than three years. For fresh tar materials the release seems to be limited by retarded pore diffusion, while for two of three aged tars diffusion limited release influenced by dissolved organic matter (DOM) was assumed. The equilibration process was driven by solubilization thermodynamics expressed by Raoult's law. Yet, solubility enhancement was observed potentially due to the presence of organic mobile sorbents. The results show that the release of PAHs from tar phases is generally rate limited and partitioning according to Raoult's law is the driving mechanism of the exchanges process.
authors: Institute of Geosciences, Friedrich Schiller University of Jena, Burgweg 11, 07743 Jena, Germany. markus.wehrer@uni-jena.de
authors: Markus
authors: M
authors: Wehrer
authors: Thilo
authors: T
authors: Rennert
authors: Kai Uwe
authors: KU
authors: Totsche
mesh_terms: D003033:Coal Tar / Q000032:analysis*; D004058:Diffusion; D004784:Environmental Monitoring; D007700:Kinetics; D008956:Models, Chemical; D011084:Polycyclic Aromatic Hydrocarbons / Q000032:analysis*; D013816:Thermodynamics; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D011084:Polycyclic Aromatic Hydrocarbons; D014874:Water Pollutants, Chemical; D003033:Coal Tar