314 THE DEEP SEA 



Table VI. Deep Water of North Atlantic Origin 



Difference from Crude Age, 

 Depth, meters aC'^, %c Source, %o years 



Surface (19) 

 200-400 (3) 

 800-1100 (8) 

 122-2500 (7) 

 1200-2500 (10) 



(Western Boundary) 

 2500-4000 (15) 

 >4000 (15) 



A^ote. Quantities in parentheses indicate number of samples. 



Similar estimates for the South Atlantic are given in Table \ II. 

 The mean residence time for the Antarctic bottom water (AABW) 

 is less than 200 years. Since few measurements exist for surface 

 waters in the South Atlantic and Antarctic with temperatures 

 from 4 to 8 degrees or less than 1 degree, a greater uncertainty 

 must be attached to the Antarctic bottom water and Antarctic 

 intermediate water (AAIW) residence times. The data suggest 

 shorter residence times than for waters of North Atlantic origin. 



In order to evaluate whether the system is in steady state as 

 assumed for these age calculations, a model of the entire ocean- 

 atmosphere system must be constructed. Since both sufficient C^^ 

 data and details of oceanic mixing patterns are lacking, a truly 



Table VII. Deep Water of South Atlantic Origin 



Difference from Crude Age, 

 AC^^ %o Source, %o years 



Surface 1-3° (3) 

 Surface 3-7° (2) 

 Surface 12° (16) 

 200-400 m (6) 

 600-1200 m (6) 

 1200-2500 m (3) 

 >500m (3) 



