studies. Similar constraints can be anticipated for other elements. The 

 mode of manganese and iron oxide deposition on the ocean floor and 

 its role in modifying ocean chemistry are still not well known. 



4. The movement of bottom sediments by bottom currents or down- 

 slope movements may result in the solution of some components such 

 as biogenic silica and calcium carbonate but may also transport them 

 into deep pockets where they are protected from solution. The injection 

 of silicon-32 with stable silicon into bottom water originating in the 

 Antarctic region by the solution of biogenic silica during current 

 transport is of interest in deciphering water paths and the material 

 balance for both sihcon-32 and stable silica. The association of barium 

 with biogenic silica deposits in the Antarctic region is of importance 

 in understanding the geochemical cycle of this element. Sedimentation 

 rates in the deep sea should be measured using isotopes with diiferent 

 half-lives to estimate the flux of material into bottom waters. 



5. The environment of the midocean ridge areas is diff"erent from 

 that of the abyssal plains in a number of ways that can influence the 

 composition of the sediments of this region. The association of high 

 concentrations of calcium carbonate, barium, organic matter, and some 

 metals with the high ridge areas has been described. The reasons for 

 each of these elements being found in the same general location may 

 not be the same. Biologic, sedimentologic, and volcanic causes may 

 combine in one location to give the end result of enrichment of chemicals 

 along the ridge area. To understand the environment of the ridge area, 

 it is important to unravel these processes. The use of research sub- 

 mersibles is admirably suited to such studies of the ridge. Further 

 consideration of fluxes at the sediment-sea interface are contained in 

 pp. 62 to 84 of this document. 



NUMERICAL MODELS IN CHEMICAL OCEANOGRAPHY 



One major area that has been neglected in chemical oceanography 

 is the incorporation of major and minor element distributions into 

 ocean circulation models. An important ingredient of such models is 

 an understanding of the chemical and physical processes that alter the 

 concentrations of elements within the water column. A water mass is 

 an open system that exchanges material by advective and diffusive 

 processes, and interacts with the descending particulate flux. Simple 

 mass balance models are often adequate for such concepts as apparent 

 oxygen utilization (AOU). However, such concepts oversimplify the 

 complex nature of the actual processes occurring in the oceans. The 

 first aspect of the modeling process should emphasize the incorporation 

 of transport and particulate interaction terms into the simple mass 

 balance. 



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