Dispersants, Salinity and Prince William Sound for Prince William Sound Regional Citizens ’ Advisory Council (PWSRCAC)

This paper is a summary of the effects of water salinity on chemical dispersion, especially those effects related to effectiveness. Surfactants are the active ingredient in dispersants. The surfactant is more lipophilic, or oil-loving, in freshwater and increases in hydrophilicity (or water-loving) as the salinity rises. The stability of the resulting droplets is also dependent on salinity. This is due to the increasing ionic strength of the water as salinity rises. As the salinity rises above a certain point, which depends on the particular type of surfactant, this increased force results in more surfactant molecules leaving the oil drop entirely. While the theoretical possibility of freshwater dispersants exist, the stability of dispersions in less saline waters would be less. This report reviews several older dispersant tests. Data from these tests were separated from more recent data because older testing procedures and analytical methods are not as accurate as today’s methods. Newer testing is reviewed as well. This testing is marked by the use of analysis by chromatography and very strict protocols in operating the dispersant tests themselves. These tests are marked by having standard deviations less that 10 % and often less than 5%. The conclusions from both recent and older studies are the same