point out that the dispersants used during the Torrey Canyon incident were 

 mostly solvent-based and highly toxic, killing marine organisms at concen- 

 trations of 10 mg/1. Chemicals available today are much less toxic. 



plOOUCl^,,^ _□, 



*3 fua oil 



SOUTH LOUISIANA 

 CtUDE 



IAOO 



ouoe 



KACMAOUERO 

 ClUDf 



SANTA BARBARA IUNKEI C 



CMIDI 



Figure 1. Dispersant effectiveness as a function of oil viscosity. 



APPLICATION 



The water eductor method is the common means of spreading dispersants. 

 A controlled amount of dispersant is educted into a water stream such as a 

 fire hose. This water jet is an effective vehicle or carrier for the dispers- 

 ant and provides good coverage in treating the slick. 



This application procedure, although compatible with a water-based system, 

 may be incompatible with a petroleum-based system. The incompatibility occurs 

 because a dispersion of the petroleum solvent-in-water emulsion is formed 

 as soon as the surfactant system is educted into the water stream; this accounts 

 for the milky white appearance of the water after such applications (Figure 2). 

 In this state, it is difficult for the surfactant to transfer from its thermo- 

 dynamically stable location at the petroleum solvent/water interface to the oil 

 spill/sea water interface. For a petroleum-based system, therefore, application 

 of the chemical directly onto the oil slick is a more effective application 

 method. 



98 



