20 GOLDBERG [CHAP. 1 



biological activity in this environment. The cool, CCVrich waters that enter 

 the shoals from the open sea are heated by sunlight. The resultant temperature 

 increases cause the solubility product of calcium carbonate to fall. Further, the 

 carbon dioxide content decreases and is accompanied by the consequential 

 increase in carbonate ion concentration. The extensive photosynthesis in the 

 area also causes a decrease in the carbon dioxide concentration. The net effects 

 then are the reduction in the solubility of calcium carbonate and an increase in 

 the concentration of the reactants. carbonate and calcium ions. 



4. Space and Time Distributions of the Elements 



Depth distributions of such chemical species as phosphate, nitrate and 

 dissolved oxygen gas have proven especially valuable in understanding the 

 major biochemical cycle in the sea, the primary production of organic matter 

 by photosynthesis in surface waters and its subsequent combustion by oxygen 

 at greater depths. Similarly, other vertical abundance profiles of reactive in- 

 organic elements have been useful for elucidating their chemical reactions 

 during residence in the marine biosphere. 



For example, the geochemical behavior of barium is strongly shown in its 

 concentration increase with depth in the oceans. Chow and Goldberg (1960) 

 found surface concentrations were of the order of 10 [j.g of barium per liter 

 whereas at depths of 4000-5000 m values three to six times higher were en- 

 countered (Table VI). The maximal values barium can attain, if its con- 

 centrations are determined by the precipitation of barium sulfate, go through 

 a minimum as a function of depth. The solubility product of barium sulfate, at 

 one atmosphere, decreases going from 25° to 0°C by a factor of 2 (Bjerrum 

 et al., 1958), accounting for an initial decrease in barium with depth. Using the 

 data of Owen and Brinkley (1941), Chow and Goldberg calculated that the 



Table VI 

 The Barium Concentration in the Pacific Ocean Waters 



