The hydrography of" the Gull" of Venezuela 



131 



organic matter to exhaust the oxygen dissolved in the water. In the Strait of Maracaibo 

 the water is flushed out each season by escaping lake water, to be replaced again with 

 more saline water when the outflow slackens in the dry season. The oxygen content 

 of the deeper water of the Strait is reduced to values comparable to those in the Gulf 

 in the course of two or three months. Thus it is needless to assume that much more 

 time is required to produce the conditions observed in the deeper parts of the Gulf. 





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TOTAL PHOSPHORUS , /^^A/ \ 



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Fig. 13. Relation of oxygen and total phosphorus content of samples collected in Sections ill and V. 

 The slope of the envelopes is that required by the complete oxidation of organic matter from plankton 

 of average composition; i.e., 2-35 ml Oo is consumed in oxidizing organic matter containing 1 ;x gA 



phosphorus 



COUNTERCURRENT SYSTEMS AND BIOGENETIC PROPERTIES 



The major ions of sea water exist in all parts of the ocean in very nearly equal 

 proportions. It is a remarkable fact that, in contrast, most of those components which 

 enter into the structure and chemical activity of living organisms are distributed in 

 very different proportions in different parts of the oceans. Phosphate and nitrate, for 

 example, are more than twice as abundant in the deep water of the Pacific and Indian 

 Oceans than in the North Atlantic, although the concentrations of the major ions are 

 approximately the same. 



