the difference between the P-V-T properties of seawater and pure water, 

 one can magnify the effect of sea salts, which is what one is normally 

 interested in when studying the oceans. 



The most useful form of an equation of state would be one formulated 

 in terms of the contributions of each significant solute. This would 

 make the equation of state applicable in regions where special condi- 

 tions prevail, such as in the Red Sea, or in low sahnity regions near 

 rivers or ice. Such an equation would reduce to that of pure water for 

 zero salinity, and would account for the contribution of each significant 

 solute. 



Recent work on sound absorption in the ocean has opened up several 

 questions concerning pressure-dependent chemical equilibria and 

 chemical relaxation processes in the ocean. It is clear that the Schulkin 

 and March equation (1962), originally developed to account for sound 

 absorption due to the relaxation of magnesium sulfate in the ocean 

 cannot explain the following anomahes: 



• The low-frequency relaxation of 1 kHz deduced by Thorp (1965) 

 from his analysis of long-range, deep sound channel acoustic propaga- 

 tion. The absorption below 1 kHz is greater by a factor of ten than 

 predicted. 



• The decrease with pressure of sound absorption in the 30-150 

 kHz region observed by Bezdek (1972, 1973). The pressure effect is 

 greater by a factor of two than predicted. 



• The asymmetry in absorption-per-wave-length plots in real sea- 

 water in the 30-300 kHz region obtained recently by Bezdek (1973) 

 in the ocean and also in the original work by Wilson (1951) in the labora- 

 tory. This implies another relaxation between 1 kHz and the MgS04 

 absorption at 60 kHz. 



The kinetics and equilibria responsible for these effects need to be 

 identified by careful laboratory measurements of sound absorption 

 from 500 Hz to 300 kHz due to the various solutes in seawater whose 

 concentrations are above 1 ppm. The synthetic seawater used by early 

 investigators omitted boric acid which, according to temperature jump 

 work by Fisher, Yeager, MiceU, and Brussel (1972), could be the cause 

 of the 1-kHz relaxation. The asymmetry in the high-frequency plot may 

 be due to magnesium bicarbonate which Garland and Atkinson (1973) 

 predict, on a theoretical basis, to have a relaxation frequency in the 

 10-kHz region. 



Chemical Interactions Among the Major Components 



Knowledge of ionic interactions in multicomponent electrolyte solu- 

 tions Hke seawater and body fluids is necessary (Millero, 1971a, 1973a) 



13 



