present in all living things, a study of metabolic influences on the forma- 

 tion of calcium carbonate is important. A study of the impact of life 

 processes on the calcium chemistry and alkaUnity of seawater should 

 be concerned with the biochemistry of the organism as well as the physi- 

 cochemical influence of the medium. Finally, because of the many reac- 

 tions that are influenced by pH, the buff"ering aspect of the alkalinity 

 is important to the chemistry of seawater and its stability as a biological 

 environment. 



Impact of Life Processes on Radioactive and Stable Nuclides 



Radionuclides in the ocean may be naturally occurring or manmade. 

 Naturafly occurring radionuclides are the cosmic-ray-produced species, 

 such as carbon-14, hydrogen-3, berylUum-10, uranium-238, uranium- 

 235, and thorium-232, and their many daughter products, such as 

 thorium-230, radium-226, lead-2, radium-228, protactinium-231, etc. 

 Manmade radionuchdes consist of the fission and fusion products given 

 off' by nuclear-weapon tests, controlled nuclear reactors, and power 

 generators. Some of the most important in the ocean are carbon-14, 

 hydrogen-3, strontium-90, cesium- 137, zinc-65, and plutonium-238 and 

 239 (see pp. 33). 



Life processes are important in transporting many of these nuclides 

 from surface into deep water. For example, "bomb" carbon-14 has been 

 found in the tests of foraminifera at great depths in the sea. High levels 

 of fission products have been found in fish caught in the open ocean, 

 and these fish must be important agents for transporting these nuclides. 

 (see pp. 33). 



Life processes are important in transferring radioactive elements. 

 For example, photosynthesis transfers "bomb" carbon- 1 4 from inorganic 

 to organic carbon in the marine ecosystem. Although life processes 

 have a tremendous influence on radionuchdes, the inverse relationship 

 is as much, if not more, important, but these influences are poorly 

 understood. Some fission products and plutonium may be concentrated 

 to high and possibly deleterious levels in various organs of fish and 

 higher organisms (Folsom, 1972). The effects of these radionuclides on 

 organisms needs to be assessed. 



The field of stable isotope geochemistry has an excellent record of 

 providing answers to specific questions. For example: 



1. Paleo-temperatures based on O'^/O'^ ratios. 



2. Sulfur dome origins based on S^VS^- ratios. 



3. Oil field and oil source bed correlation based on C^^/C^^ ratios. 



4. Water cycles based on O^^/O'® ratios. 



Several parts of stable isotope geochemistry are now ready to yield 

 important information: 



66 



