Missing carbon problem

Pg C/year, similar to the minimum values of Woodwell et al. (1983), but the trends during the past century differ significantly (Fig. 11-23). Rather than finding a sink for the fossil fuel CO2 that the oceans could not accommodate, in the terrestrial biosphere we find a source The "missing sink" problem is yet more severe. Obviously our knowledge of the global cycle of carbon is inadequate to get ends to meet. 

The problem of missing soil carbon data was resolved using power (Bennema 1974) and exponential (Arrouays and Pelissier 1994) type equations to model soil carbon distribution with depth. Bemoux et al. (1998a) determined that both models were well adapted for tropical forested Oxisols, and that the exponential model is more precise and produces better data. Bemoux et al. (1998b) extend the use of the exponential model to the other Amazonian soil type, mainly the Podzolicos (Table 11.2). 

This two-faceted problem requires consideration in two separate stages, since two apparently disparate mechanisms appear involved in the production of compounds II and III. For one thing, while II contains the same number of skeletal carbons as does the starting tosylate, one carbon, two hydrogens, and an oxygen atom are missing in the final structure (III). 

The mass balance problem can be solved readily for organic carbon. The filtrates of each fraction filtered sequentially are missing organic matter of a size larger than the membrane cutoff. By measuring either the retentate or filtrate TOC in mg/L, the mass of TOC in each successive filtrate fraction can be determined if it is assumed that (I) the TOC of molecular size less than the membrane cutoff passes in proportion to the volume (2) the membrane behaves ideally as a molecular sieve at each cutoff and (3) the volume is known. Given these conditions, a system of equations (Table V) for either retentate or filtrate fractions can be... 

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