82 



The Sea-water and its Physical and Chemical Properties 



that compared with the long cycles of water HgO, there are only short vertical cycles. 

 This is a consequence of the non-existence of a liquid carbon dioxide phase. Accord- 

 ing to Rankama and Sahama (1950) the total mass of the carbon dioxide in the 

 atmosphere is 23 x 10^^^ g. 



It should be emphasized that the existence of a pressure difference in the carbon 

 dioxide cycle between the atmosphere and the ocean will always lead to an interchange 



ATMOSPHERE 



+ 3+4 -1 



A A 



+ 2 



-2 



-2 



ia 



t -3 -4+29-28 i--^-2^^ 



XmDRt 





L 



LJTHOSPHEfiE 



sssg 



Eifi^ftJE^ 



Fig. 43o. Schematic diagram of the carbon dioxide cycles in the atmosphere, the hydro- 

 sphere and the lithosphere. 100 relative units = 16 ■: 10^^ g CO2 per year or 0032 g cm"^ 

 years"^ Note that biological processes are dominant, particularly those of marine life. 

 Balances: atmosphere + 9 — 5 = 4; lithosphere -y- 29 — 35 = —6; hydrosphere 

 - 62 - 60 = 2: total -r 100 - 100 = 0. The atmosphere gains 004 : 16 x lO^^ = 0-64 

 X 10'^ g per year or 3-2 x 10'" g in 50 years which corresponds to 14% of the estimated 

 total CO2 amount of 23 : 10^^ g present in the entire atmosphere. 



->• , Release from rocks; • 



ooooo>. , Forest and prairie fires ; 

 /^^ , Respiration; > 



tension differences in the sea; 



► ••••»- , Deposition in sediments and minerals; 

 • ••••»> , Combustion of coal and oil ; 



, Assimilation; »- , Flux following CO2 



f = value smaller than 0-5 rel units 

 (Lettau, 1954). 



between the two media that will cease only when equilibrium is established. Schlosing, 

 in laboratory investigations, has clarified these exchange phenomena and shown that 

 the sea always has a levelling effect on pressure differences that occur between the 

 atmosphere and the sea. Since the sea has a carbon dioxide content several times 

 greater than that of the atmosphere it suppresses fluctuations in the atmospheric carbon 

 dioxide content and it tends to hold the atmospheric carbon dioxide at a constant 

 value. In this respect the sea acts as a "regulator" of the carbon dioxide content, 

 opposing changes in the content of this gas in the atmosphere. Nevertheless, recent 

 investigations have shown that the variations in carbon dioxide content in both the 

 ocean and the atmosphere are of the same order of magnitude. The sea in acting as a 

 damper thus undergoes the same variations as the atmosphere, and under these 

 conditions it is not easy to decide which is the "regulator" and which is the passive 

 part. When changes occur and a new equilibrium is established, the sea of course takes 

 up a much larger amount of carbon dioxide than the atmosphere. According to Table 

 32 the annual production of carbon dioxide amounts to about 0-0008 g/cm^ of the 

 Earth's surface. The amount of carbon dioxide already present in the atmosphere 

 amounts to about 0-4 g/cm^. If the whole of the carbon dioxide produced remained 



