CHEMISTRY IN THK OCEANS 595 



A clue to the marine geochemical behavior of barium may be 

 found in its distribution in sea water. Dr. T. Chow and I have 

 recently found barium existing in sea water in a state of under- 

 saturation with respect to precipitation of the sulfate and with 

 concentrations ranging between 10 and 70 ng/liter. The lower 

 values are found in surface waters, and there is a consistent 

 increase in barium content with depth. The depth profiles are 

 somewhat similar to those previously reported for radium. 



Possibly, the release of high concentrations of sulfate ion, 

 resulting from the oxidation of organically bound sulfur in bio- 

 logical debris in the oceans, can result in a consequential precipi- 

 tation of barium sulfate in the microenvironment of this organic 

 material. As simultaneous sinking and combustion of this organic 

 matter occurs in the oceans, part of the incorporated barium may 

 be returned to the sea water through dissolution of the barium 

 sulfate. Part of the barium may end up in the sediments. Further, 

 one can conceive that any oxidation of organic matter in the sedi- 

 ment may result in the uptake of barium by the mechanism 

 illustrated above. Such processes would result in an increase in 

 barium with depth and its accumulation on the sea floor. 



Early German and Russian workers pointed out the striking 

 accumulation of heavy metals over sea water by a whole spectrum 

 of marine organisms. Iron, vanadium, zinc, and nickel were 

 amassed by the biosphere to average enrichments over sea water 

 by factors of tens of thousands. Recently, a wealth of values on 

 the heavy metal contents of members of the marine biosphere has 

 resulted from problems involving the disposal of radioactive wastes 

 and bomb fallout. Such work has strengthened the observation of 

 the concentration of heavy metals in organisms of the sea. These 

 metals are retained by strong chemical bonds and cannot be 

 eluted (washed out) by repeated rinsings with fresh or sea waters. 



The relative concentration factors of metals in the marine 

 biosphere as compared with those of sea water closely parallel 

 the order of stability of metal ions with a variety of organic 

 complexing agents (Goldberg, 1957). If one takes the stability 

 constants of metals forming organic complexes with a large suite 

 of organic complexing agents, independent of the functional 

 group, the Increasing order of stability for the metals shows a co- 



