Similarly, the rate of injection into the deep sea of those chemical 

 constituents that "travel" in association with organic matter depends 

 critically on the fraction of organic matter not oxidized in the upper 

 layers. Therefore, important questions to be answered are as follows: 



1. What is the recycling efficiency (ratio of oxidation to production) 

 in the upper layers and how does it vary with depth, geographic position, 

 and season? 



2. What are the chemical and physical forms of organic matter in- 

 jected into the deep sea? 



3. At what rates are they injected. 



4. What are the modes and rates of their interactions with one another 

 and with the inorganic constituents? 



5. What is the rate of oxidation of organic matter in the deep sea? 



6. What quantities and what forms of organic matter reach the bottom? 



7. How much is oxidized or solubihzed at the bottom? 



8. What is the rate of loss of carbon to the sediment? 



Some of these questions can be answered by stable and radioactive 

 isotope studies (e.g. carbon- 13 and carbon- 14) coupled with measure- 

 ments of concentration changes in inorganic and organic phases. Others 

 require sophisticated methods of organic analyses, of which some are 

 available and others are being developed or need to be developed. 



DETERMINATION OF THE FLUXES OF NOBLE GASES, 

 INCLUDING RADON, AND LOW-MOLECULAR-WEIGHT 

 ORGANIC GASES FROM THE SEDIMENTS INTO THE 

 OVERLYING WATERS 



What effect do the dissolved gases in ocean water have on life proceses 

 and how are they related to boundary conditions for models involving 

 advective and convective mixing in deep waters? What are the diagenetic 

 processes in marine sediments, including the formation of gases in sedi- 

 ments? These are fundamental questions yet unanswered. There is ample 

 indirect evidence for the diffusion of noble gases from the sedimentary 

 column to the overlying waters. Helium, produced in the earth's crust 

 as a result of radioactive decay of isotopes of the uranium and thorium 

 series, is found in higher concentrations in deep seawater than expected 

 from solution of air. Further, there appears to be diffusion of noble 

 gases in the sedimentary column as a consequence of thermal gradients. 

 Quantitative measurement of fluxes of gases such as the noble gases 

 are yet to be made, even though such numbers would provide important 

 boundary conditions for models of the mixing and movements of deep 

 waters. 



42 



