7. GASES 



R. Revelle and H. E. Suess 



1. Introduction 



The total volume of the oceans is 1.37 x lO^i liters. The amount of gases in 

 the terrestrial atmosphere, expressed in liters of gas at standard temperature 

 and pressure, is 4.32 x lO^i liters, or about three times larger than the volume 

 of the oceans. The solubility of gases in a liquid is in general expressed as an 

 absorption coefficient, a, giving the ratio of the concentration of the gas in the 

 liquid to that in the gas phase. This ratio is independent of the partial pressure 

 of the gas and is a function of the temperature. For the atmospheric gases the 

 absorption coefficient in water is small, of the order of a few per cent. Because 

 of the salting out effect, it is even smaller in sea-water than in fresh water. The 

 fraction of the atmospheric gases dissolved in the oceans is, therefore, in general 

 small compared to their total amount present on the surface of the earth. 



Table I 

 Gases in Deep Ocean Water as Compared with Their Concentration in Air 



Percentage of 

 total gas on 

 Milliliter per Milliliter per earth dissolved 



liter air liter water in ocean 



O2 210 2 to 8 0.5 



N2 781 13 0.6 



He 52 X 10-4 0.5 x 10-4 0.3 



Ne 182x10-4 1.8x10-4 0.3 



A 9.32 0.32 1.2 



Kr 10x10-4 0.6x10-4 2 



Xe 0.8 X 10-4 0.07 x 10-4 3 



CO2 0.3 50 6000 



An exception to this is carbon dioxide. This gas is present in ocean water 

 chemically bound in the form of carbonate or bicarbonate, in amounts that 

 exceed that of gaseous CO 2 in the atmosphere by about a factor of 60. The 

 solubility of CO 2 in sea-water depends on its alkalinity and temperature. The 

 greater part of this chapter will deal with the CO 2 equilibrium between ocean 

 and atmosphere, a system about which the least has been known and on which 

 the greatest progress has been made in the last few years (Revelle and Fair- 

 bridge, 1957). However, it will be shown that our knowledge of the quantities 

 involved is by no means satisfactory at the present time. 



Table I lists the average content of gases in deep -ocean water in comparison 

 with the amounts present in air. The data for the rare gases He, Ne, Kr and Xe 

 are from a single analysis by Hintenberger, Konig and Suess (unpublished) of 



[MS received March, 1961] 313 



