Carbon cycle summary figure

FIGURE 14.11 Summary of global carbon cycle. Amount (in gigatons of C = 109 metric tons = fO1 g of C). Reservoirs are shown in parentheses, and fluxes (gigatons of C per year) are indicated by arrows. Note that the time scales associated with the various processes vary (adapted from IPCC, 1996). 

Figure 15.19 gives a description of the global carbon cycle. The inventories of the various reservoirs were already given in Table 4.1, where we noticed that the atmosphere is a relatively small reservoir with large fluxes, so that the residence time of C in the atmosphere is only a few years. The carbon system is not at steady state. Because of fossil fuel combustion and possibly also because of deforestation, the inventories of C in the atmosphere and hydrosphere are increasing. The flux related to fossil fiiel combustion is nearly 1 % of the total atmospheric CO2 reservoir. The flux due to land use is more con-troversal but is probably 1-2 X 10 mol C . As the summary at the bottom... 

A summary of the sequential reactions of the -oxidation cycle and the relationship of the overall process to energy metabolism in mitochondria is shown in Figure 3.20. Two carbon units (as acetyl-CoA) are removed from the fatty acyl-Co A substrate by the successive action of four enzymes - acyl-CoA dehydrogenase, enoyl hydratase, a second dehydrogenase and a thiolase. These enzymes are detailed in Table 3.12. 

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