104 



BKOECKER 



[CHAP. 4 



-3 /3 



0.09 A U 



| 0.09 A U I 



)1 f 



0.66 V.U 



"43 



'POLAR" 

 _ OCEAN 

 C/Cfi, -- 0.885 



226 Ra = l.0~ 



T C o 2 =l40YR 

 T D .S.= 80YR 



FOUR RESERVOIR MODEL (IT) 



.£i f\ 



t 60 A U 



2 



® I SURFACE OCEAN 



C/C A = 0.970 

 0.30 V.U. ft... 226 Ra = 0.5 .ft. T D.S. =90YR 



T C o 2 = 30 YR 



© 



INTERMEDIATE OCEAN 

 C/C A = 0.920 

 "0.12 V.U. 226 Ra=0.5 



Tco 2 =T D . s . = 285YR 



DEEP OCEAN 



C/C^ 0.800 



226 Ra = I.O 



2 D.U. 



4.0 V.U. 



Tco2=T DS = 850YR 



8DU 



26 D.U. 



E|=J|= 10 M/MVYR 



£ 3 =I 3 =45M/M 2 /YR 



A { I, = 2.2xl0 15 M/YR 



-a 3 I 3 = 1.5 xlO 15 M/YR ( l4 C) 



'O 



ff|4=R 4 l= I.I xiO l5 M/YR ( l4 C) 

 Rzy-Rz2= l.6xlO l5 M/YR ( l4 C) 

 /? 3 4=ff43 = 0.3xlO l5 M/YR ( 226 Ra) 



Fig. 9. An example of the type of model required to satisfy the main features of the 226 Ra 

 as well as the 14 C data. The radium concentrations are given in units of 1 x 10 -13 g 

 226 Ra per liter of water. The values of .R43 and -R34 are based on 14 C data. In this 

 case the ratio of the polar to surface ocean exchange rate is fixed by the 14 C dis- 

 tribution. 



the exchange rate of CO 2 across the polar ocean surface must be about four 

 times that for the remainder of the ocean in order to supply sufficient 14 C to 

 maintain the deep waters (over 90% of the 14 C decaying in the deep ocean being 

 supplied through the polar ocean surface). Thus if the 226 Ra distribution does 

 result from radioactive decay, the oceans must be characterized by two nearly 

 independent circulation systems separated by a relatively impermeable 

 boundary at perhaps 1000-m depth. The intermediate reservoir is necessary in 

 such a model in order to explain the 14 C concentration observed in the surface 

 ocean without resorting to unreasonably small ocean-atmosphere exchange 

 rates. 



8. 90 Sr Distribution 



The measurements of 90 Sr at various depths in the Atlantic (Bowen and 

 Sugihara, 1960) summarized in Table V suggest that mixing to depths of 500 m 

 or more occurs in less than five years. When considered in conjunction with the 

 14 C and 226 Ra data, a rather serious problem arises. The 14 C data for waters 

 from 200 to 500 m fall about halfway between those for the water above and 

 for that below. If these waters are being mixed with the surface waters as 

 rapidly as is seemingly required by the 90 Sr data, then, in order to maintain 

 the intermediate 14 C values, an equal quantity of deep water must be mixing 



