The Sea-water and its Physical and Chemical Properties 



79 



lOOO 



2000 



300 



4000 



5000 



600O 



Fig. 42. Carbon dioxide pressure cross-section through the subtropical part of the South 

 Atlantic (8-5 -13' S., profile VIII from the "Meteor" Expedition; given in 10"* atrri). 



higher latitudes and reduce the carbon dioxide content of the water at middle depths 

 (2000^000 m). 



(2) The decomposition of dead organisms that takes place principally in the upper 

 layers beneath the transition layer. In shallow seas dead organisms reach the bottom 

 before decomposition is complete and the carbon dioxide pressure thus increases down 

 to this depth. In the deeper layers of the major oceans decomposition occurs largely in 

 the upper layers and the carbon dioxide pressure then decreases with further increase 

 in depth. 



(3) The respiration and oxidation processes that produce carbon dioxide proceed 

 more rapidly at the higher temperatures in shallow depths than at greater depths where 

 the temperature is lower. 



All three factors combine to bring about the observed distribution, although a sta- 

 tionary state can naturally only occur when the addition and the consumption of 

 carbon dioxide are in equilibrium. However, for quantitative considerations of this 

 type there is as yet no numerical estimate of the effect of the different processes. 



In the last hundred metres immediately above the sea bottom there is a more or less 

 large increase in the carbon dioxide content above the almost constant value of the 



