HR: 1340h
AN: H23A-1408    [Abstracts]
TI: Stability and Transport of NAPL Droplets in Aqueous Solutions
AU: Yaron-Marcovich, D
EM: dana.marcovich@weizmann.ac.il
AF: Weizmann Institute of Science, Department of Environmental Sciences and Energy Research, Rehovot, 76100 Israel
AU: * Dror, I
EM: idror@weizmann.ac.il
AF: Weizmann Institute of Science, Department of Environmental Sciences and Energy Research, Rehovot, 76100 Israel
AU: Berkowitz, B
EM: brian.berkowitz@weizmann.ac.il
AF: Weizmann Institute of Science, Department of Environmental Sciences and Energy Research, Rehovot, 76100 Israel
AB: Situations are presented under which aqueous concentrations of NAPLs can be higher than maximum solubility values, in both fresh and salt water. The behavior of several organic contaminants in water at concentrations above their solubility was studied, and their diffusion in a salt water gradient was determined. A previous study showed that such contaminants undergo enhanced transport from source to collector solutions when the source contains dissolved salts. In natural, open system conditions, salinity differences between seawater and freshwater remain high. As a consequence, the existence of an enhanced transport mechanism, which drives NAPLs from polluted marine and other saline environments into freshwater coastal aquifers, is examined. Solutions of benzene, toluene, xylene, trichloroethylene and a mixture of them were prepared in excess in freshwater and in saltwater, and solution stability was studied. High organic concentrations tend to remain stable in both fresh water and salt water. In salt water, for example, toluene and xylene concentrations remained as high as 14 and 26 times their solubilities, respectively, over a period of 6 days, while in fresh water, their concentrations remained 8 and 30 times their solubilities over the same period. This phenomenon is attributed to the presence of stable organic droplets, which was verified using optical microscopy. Experiments on diffusion of benzene solutions demonstrated a three-fold concentration increase in the collector cell when the source cell contained salt water rather than fresh water. These results indicate that the presence of salt can enhance the concentration of organics in aqueous solutions, as well as their diffusion.
DE: 1829 Groundwater hydrology
DE: 1831 Groundwater quality
DE: 4251 Marine pollution (0345, 0478)
SC: Hydrology [H]
MN: Fall Meeting 2005