12 



STUIVER 



E 



I 

 H 



Q- 

 LU 



Q 



1000 



2000 



3000 



4000 



5000 



-35(18) 



m 



NACW -71(3) -92(2) , -61(6) 



■-98(8), -118(6) 



-46(16) 



SASW 

 AAIW 



-72(8) 



-105(15) 



-102(5) 



-130(3) 



AABW 



104(16) 



flrffZfiftfrhL 



-144(3) 

 _J 



/ZRfo* 



60° N 



40° 



20° 



20° 



40° 



60° S 



LATITUDE 



Fig. 2 Average ' 4 C specific activities of bicarbonate in the Atlantic 

 Ocean, as given by Broecker. 2 The number of samples measured is given in 

 parentheses; the other values give the per mille ' " C deviation from the Lamont 

 standard. Water masses are given by NACW (North Atlantic Central); SASW 

 (South Atlantic Surface); AAIW (Antarctic Intermediate): NADW (North 

 Atlantic Deep); and AABW (Antarctic Bottom). 



The preceding data depict a general northward and southward movement, of, 

 respectively, the bottom Pacific and Atlantic ocean waters. Bien and co- 

 workers 7 estimate from the change in specific 14 C activities an overall 

 northward velocity of 0.6 to 0.7 mm/sec for the deep Pacific waters. 



The complications introduced by particulate transport to the deep ocean are 

 neglected in many box-model studies. However, for a simple two-box model, 



Lai has shown that the calculations of residence times are not affected by 

 particulate transport, since the ratio of the specific activities turns out to be 

 independent of the particulate flux. Its effect is to reduce the concentration of 

 both C and C0 2 in the mixed layer, affecting both to the same extent. 



Particulate (or "biotic") transport is of importance for differences in both 

 the specific C activity and the total C0 2 concentration between surface and 

 deep waters. A typical profile 19 in the Pacific at 28 29'N, 121°38'W is given in 

 Fig. 4. The depletion of total C0 2 in the surface waters and the C0 2 maximum 

 at a depth of about 1 to 2 km are attributed to biotic transport. 



In a two-reservoir model, the net input of 14 C in the deep reservoir is equal 

 to XCdNj (where Cj = specific 14 C activity and Nj = total number of C0 2 

 molecules in the deep-ocean reservoir). This net input is provided by the 

 particulate carbon dissolved in the deep ocean and by the net flux of C0 2 over 



