THE PHYSICAL CHEMISTRY OF SEA WATER 555 



good basis for a machine of perpetual motion. In reality, the lower 

 solubility at low pressures would be more than counterbalanced 

 by a concentration gradient which would make the concentration 

 lower at the upper end. The tendency would be for the solid to 

 dissolve at the upper end and precipitate at the lower: the equi- 

 librium position of a heavy solid is, after all, at the bottom of the 

 column. Currents in the ocean will, however, prevent this diffusion 

 equilibrium from being achieved, and so one may imagine that 

 water from the depth, saturated with a certain solid, is lifted to 

 layers with lower pressure where the solid will precipitate. 



In our imaginary model, we must treat the differences in 

 pressure like those in temperature and work with some average or 

 effective equilibrium constant. 



Finally, it may be said that the life processes will take the sea 

 water far from the equilibrium composition. This is true especially 

 in the surface layer, containing perhaps 5% of the bulk of the 

 ocean, where the concentrations of C, P, Si, and some other 

 elements may be considerably changed. In the remainder of the 

 ocean, however, it seems that the processes working toward 

 equilibrium will predominate. 



There are also pockets in the ocean, like the depths of the Black 

 Sea, with stagnant water, oxygen deficit, and low pH : these exist, 

 however, only because they have so little contact with the re- 

 mainder of the ocean. We shall neglect these in the following 

 discussion, which may, perhaps, give a useful first approximation. 



Data Used; Correction Terms 



The concentrations of various substances in sea water have been 

 taken from Sverdrup et al. (1942, pp. 173, 176), Harvey (1957, pp. 

 140, 224), and Richards (1957). Goldschmidt's estimates on the 

 amounts of various substances in primary rock and sediments have 

 been taken from the original papers (1933, 1937a,b) or as recalcu- 

 lated and completed by Rankama and Sahama (1950, pp. 39, 295). 

 In addition, some information on the composition of pelagic 

 sediments has been taken from a paper by Goldberg and x\rrhenius 

 (1958). 



The equilibrium constants for solubility, complex formation, or 



