1 . Hazards in working on an ice flow close to its edge 



2. The inability to evaluate properly the physical, chemical and 

 biological nature of the undersurface of the ice 



3. The loss of sampling integrity caused by the borehole and contact 

 of the seawater with the atmosphere 



4. Serious disturbances that arise when making boundary-layer 

 chemical observations from surface ships operating within the ice. 



In regions that undergo surface freezing there are intense seasonal 

 changes in dissolved carbon dioxide (Kelley, 1970) and probably in 

 dissolved oxygen to a lesser extent. With the exception of major up- 

 welling areas (Gordon et al., 1971; Kelley and Hood, 1971; and Kelley 

 et al, 1971) and shallow coastal systems (Gordon, 1973), seasonal 

 carbon dioxide variations in surface waters of the polar seas have 

 shown the largest temporal variations in the world's oceans. 



Many sampling problems might be overcome by using a research 

 submersible that can maneuver under the ice as well as in the open 

 water. This capability could be coupled with the use of in situ sensors 

 (for salinity, temperature, pH, and dissolved oxygen), with control 

 and visible observation of the sampling location, and with facilities for 

 on-board data readout. Such capability would allow for the design of 

 experiments addressed to the measurement of horizontal and vertical 

 gradients under and at the margins of the ice and rates of formation 

 and decay of these gradients. Information of this kind would provide 

 valuable data bearing on the physical, chemical, and ecological pro- 

 cesses acting in the polar seas. 



PARTICULATE FLUXES IN THE OCEANS 



The quantitative aspects of the transfer of particles from the upper 

 layers of the ocean to its depths and the relative importance of each 

 of the mechanisms of transfer are unresolved questions in chemical 

 oceanography. 



Vertical transport by settling particles is significant in governing 

 the distributions of chemical species in the ocean. Such transport hastens 

 the downward movement of radioactive contamination, pesticides, 

 herbicides, or other products of man's activities. Our present knowledge 

 of particles is largely confined to bulk compositional analyses, light- 

 scattering properties, and theoretical settling rates. We need the ability 

 to predict the properties of zones of high particulate load (i.e. nepheloid 

 layers), the extent to which various substances in the sea will be incor- 

 porated in or upon settling particles, the rate of downward transport, and 

 whether such material ultimately remains with the particle or escapes 

 into the surrounding water. 



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