APPENDIX 



369 



LIVING 

 CARBON, ? 



DEAD ORGANIC 

 CARBON. ? 



ATMOSPHERE 



C0 2 -C, 670 a 



Fossil-fuel 



combustion, 



3.6 b 



CH,, 3 



CO, 0.3 



Troposphere, 610 

 Stratosphere, 60 



Gross 



photosyn- 

 thesis, 100 



Hetero- 

 trophic 

 respiration 

 and fire, 

 13 



Plant 

 respira- 

 tion, 50 



LIVING 

 ORGANIC 

 CARBON 

 (mostly plant), 

 833 c 



Detritus 

 transfer, 

 37 d 



Fire, ? 



DEAD 

 ORGANIC 

 CARBON, 

 700 e 



LAND 



Decom- 

 position, 

 37 



Detritus 

 and dissolved 

 carbon transfer, ? 



FRESHWATERS, 

 330 



'////"/ 



Flow to 

 oceans 



Rock 

 weathering, ? 



Solution 

 input, 100 



0.2 to 1 



Gross 



photosyn- 

 thesis, 50 



V 



Solution 

 loss, 98.2 



V 

 Net flux, 

 1.8 



LIVING 



ORGANIC, 



1.5* 



Plant 

 respira- 

 tion, 

 25 



Detritus 

 transfer, 

 209 



Inorganic 

 carbon, 

 5009 

 A 



y ; ; ; / /,-?,-/ /'al 



Layer 



mixing, 



459 



OCEAN 



DEEP 



LAYERS 



OCEAN 



SURFACE 



LAYERS 



Decompo- 

 sition, 359 



Layer 

 mix- 

 ing, 



H409 



DEAD 

 ORGANIC 

 CARBON, 

 1000 h 



Decompo- 

 sition, 59 



Inorganic 



carbon, 



35,0009 



SEDIMENTS 



FOSSIL FUEL, 

 10,0009 



Sedimentation, >l9 



f / / / / / 



DIFFUSE-CARBON AND 

 INORGANIC-CARBON SEDIMENTS, r 

 20,000,0009 



/ / / a 



> 1 / -r 



Solution, ? 



Fig. 1 Diagrammatic model of the global carbon cycle. Estimates are given 

 where possible; sources of these estimates are given below. Question marks 

 indicate that no estimates are available. Figures are all in billions of metric 

 tons of carbon and are derived from estimates of Brookhaven Symposium 

 participants unless otherwise noted. The following are alternative estimates: 

 (a) Other estimates are 683 (SCEP, Ref. 1, page 161) and 700 x 10 9 tons 

 (Bolin). 2 (b) SCEP, Ref. 1, page 304. (c) Bolin 2 estimates 450 x 10 9 tons, 

 (d) Bolin 2 estimates 25 x 10 9 tons (e) Bolin, 2 based on Delwiche's 3 nitrogen 

 estimate and a carbon/nitrogen ratio of 12, an alternative estimate is 

 9000 x 10 9 tons, (f) Bolin 2 estimates 10 x 10 9 tons, (g) Bolin. 2 (h) Bolin 2 

 estimates 3000 x 10 9 tons. 



