14 



Mary Alys Plunkett and Norris W. Rakestraw 



matter is very resistant to bacterial action and does not change significantly during 

 storage of water. 



We are unable to find any other systematic analytical error which would account 

 for such a large difference in the average concentration in the deep water. On the 

 other hand, it is difficult to explain such a difference, since the phosphate concentra- 

 tion, for example, is approximately the same in the regions concerned. The dissolved 

 organic carbon, although in lower concentration at all depths, is not uniformly 

 distributed vertically, being less in the intermediate zone, as it was in the eastern 

 Pacific. In this case, however, the zone of lower carbon concentration seems to be 

 somewhat above the steep oxygen gradient. 



It is important that we learn more about the dissolved organic matter, since it is 

 the largest fraction of the total organic matter in the sea. Although for the most part 

 it seems to be resistant and unreactive we do not know what relation it has to the 

 " oxidizable organic matter " which plays an important part in the distribution of 

 dissolved oxygen. The work reported here will be continued and extended. 



Table II. — Vertical distribution of dissolved organic carbon 



REFERENCES 



Kay, H. (1954), Untersuchungen zur Menge und Verteilung der organischen Substanz im Meer- 



wasser. Kieler Meeresforschungen, 10, 202-214. 

 Keys, A., Christensen, E. H. and Krogh, A. (1935), The organic metabolism of sea water with 



special reference to the ultimate food cycle in the sea. /. Mar. Biol. Assn. U.K., 20, 181-196. 

 Krogh, A. (1934), Conditions of Hfe at great depths in the ocean. Ecol. Mongr., 4, 430^39. 

 Rakestraw, N. W. (1947), Oxygen consumption in sea water over long periods. /. Mar. Res., 6 



(3), 259-263. 

 Von Brand, T. and Rakestraw, N. W. (1941), The determination of dissolved organic nitrogen in 



sea water. /. Mar. Res., 4 (1), 76-80. 



