FACTORS CONTROLLING CO, IN OCEANS AND ATMOSPHERE 



39 



TABLE 1 



EXCESS CATION (ALKALINITY) CONTROL 



Alk = -CP- 2S0 2 "+ . . .+ Na + + 2Mg 2+ + 2Ca 2 + - K 

 = HCO; + 2C0 2 " + H, BO, + . . . 



Example 



Supply (Weathering) 



CO, + MgSi0 3 => Mg 2+ + H 4 Si0 4 + 2 HCO, 

 From atm 



Loss (Unweathering) 



Mg 2+ + H 4 Si0 4 + 2 HCO 3 =* CO, + MgSi0 3 



To atm 



Rate increases with increasing [CO., ] ; hence [C0 2 ] of sea is fixed by cation economics. 



Table 2 



BALANCE OF MAJOR CATIONS IN THE 

 OCEAN-ATMOSPHERE SYSTEM 



Carbon Cation 



economics economics 



[HCO,] = 



[CO 2 "] [H + ] 



[co 2 



pCO : 



[HCO - ,] [H + ] 



K\ 



[CO, 



[Alkalinity] =2 [CO 2 "] + [HCO" 3 ] 



[Total CO, ] = [CO, ] + [HCO3 ] + [CO 2 '] 



exit rate of this material would double, and this would throw the ocean 

 chemistry out of balance. Output would exceed input, and the concentration of 

 all these limiting elements in the ocean would gradually drop down to half their 

 value. At this point, input and loss would again match. With twice the upwelling 

 rate and half the phosphorus content, the ocean would go back to the old 

 productivity scheme and could balance river input by loss. If the amount of 

 phosphorus coming in by rivers were to change, if the ecology of the ocean were 

 to change, and if the oxygen content of the atmosphere were to change, the 

 system would then be disrupted and the chemistry would move to a new set of 

 values that would again exert economic control on the system. 



