Carbonate fluxes

Succinic add source of carbon and energy improves metabolic balance between carbon flux from glucose and oxidation throgh TCA cyde. 

The most common way in which the global carbon budget is calculated and analyzed is through simple diagrammatical or mathematical models. Diagrammatical models usually indicate sizes of reservoirs and fluxes (Figure 1). Most mathematical models use computers to simulate carbon flux between terrestrial ecosystems and the atmosphere, and between oceans and the atmosphere. Existing carbon cycle models are simple, in part, because few parameters can be estimated reliably. 

The dynamics of these models depend strictly on carbon fluxes, but the fluxes are poorly measured or are calculated from carbon reservoir size and assumptions about the residence time of the carbon in the reservoir. In addition, model fluxes are linear functions while in reality few, if any, probably are linear. 

Rainwater and snowmelt water are primary factors determining the very nature of the terrestrial carbon cycle, with photosynthesis acting as the primary exchange mechanism from the atmosphere. Bicarbonate is the most prevalent ion in natural surface waters (rivers and lakes), which are extremely important in the carbon cycle, accoxmting for 90% of the carbon flux between the land surface and oceans (Holmen, Chapter 11). In addition, bicarbonate is a major component of soil water and a contributor to its natural acid-base balance. The carbonate equilibrium controls the pH of most natural waters, and high concentrations of bicarbonate provide a pH buffer in many systems. Other acid-base reactions (discussed in Chapter 16), particularly in the atmosphere, also influence pH (in both natural and polluted systems) but are generally less important than the carbonate system on a global basis. 

Fig. 10-15 Organic carbon fluxes with depth in the water column normalized to mean annual primary production rates at the sites of sediment trap deployment. The undulating line indicates the base of the euphotic zone the horizontal error bars reflect variations in mean annual productivity as well as replicate flux measurements during the same season or over several seasons vertical error bars are depth ranges of several sediment trap deployments and uncertainities in the exact depth location. (Reproduced with permission from E. Suess (1980). Particulate organic carbon flux in the oceans - surface productivity and oxygen utilization, Nature 288 260-263, Macmillan Magazines.)...

Emerson, S., Quay, P., Karl, D. et al. (1997). Experimental determination of the organic carbon flux from open-ocean surface waters. Nature 389, 951-954. 

Suess, E. (1980). Particulate organic carbon flux in the oceans-surface productivity and oxygen utilization. Nature 288, 260-263. 

Primary production maintains the main carbon flux from the atmosphere to the biota. In the process of photosynthesis, CO2 from the atmosphere is reduced by autotrophic organisms to a wide range of organic substances. The complex biochemistry involved can be represented by the formula... 

Box models have a long tradition (Craig, 1957b Revelle and Suess, 1957 Bolin and Eriksson, 1959) and still receive a lot of attention. Most work is concerned with the atmospheric CO2 increase, with the main goal of predicting global CO2 levels during the next hundred years. This is accomplished with models that reproduce carbon fluxes between the atmosphere and other reservoirs on time... 

Dazlich, D. A. (1996a). Simulations of terrestrial carbon metabolism and atmospheric CO2 in a general circulation model. Part 1 Surface carbon fluxes, Telliis, Ser. B, 48,521-542. 

Figure 11.1. A flow-model scheme for treating the protein routing question. Labels refer to flow rates of carbon. The total carbon flux, into and out of the body, is 1, divided into F (for protein) and 1 - F for the remainder. The significant relevant internal fluxes are between the amino acid pool (coupled to the body protein pool), and the energy metabolism pool . The extent to which protein routing is observable in the body protein composition depends on the value ofX (See Fig. 11.2). Numbers in refer to suggested isotopic fractionations associated with a metabolic path, which are consistent with the data of the Ambrose and Norr (1993) and Tieszen and Fagre (1993) data set (see Section 4.1).

If the total carbon flux through the system in steady state is = 1 unit (e.g., so many grams C per day), then the protein input (dietary) flux is called F, and the non-protein input is therefore (1 - F). The model has one internal... 

Comparison of the model-derived DIFF with the experimentally evaluated DIFF show that protein routing can be described in terms of the amount of protein synthesized from catabolic activity that is, in general it is around 20% of the mean carbon flux of the diet. A simple explanation why dp > dw is also proposed. 

Generation of mutants is also a starting point in optimization experiments, and now is the time for metabolic engineering of the astaxanthin biosynthetic pathway. Researchers should be able to manage carbon fluxes within the cells and resolve competitions between enzymes such as phytoene desaturase and lycopene cyclase. 

Sano and Williams (1996) calculated present-day volcanic carbon flux from subduction zones to be 3.1 x 10 mol/year based on He and C isotopes and C02/ He ratios of volcanic gases and fumaroles in circum-Pacific volcanic regions. Williams et al. (1992) and Brantley and Koepenich (1995) reported that the global CO2 flux by subaerial volcanoes is (0.5-2.0) x lO mol/m.y. and (2-3) x 10 mol/m.y. (maximum value), respectively. Le Guern (1982) has compiled several measurements from terrestrial individual volcanoes to derive a CO2 flux of ca. 2 x 10 mol/m.y. Le Cloarec and Marty (1991) and Marty and Jambon (1987) estimated a volcanic gas carbon flux of 3.3 X 10 mol/m.y. based on C/S ratio of volcanic gas and sulfur flux. Gerlach (1991) estimated about 1.8 x 10 mol/m.y. based on an extrapolation of measured flux. Thus, from previous estimates it is considered that the volcanic gas carbon flux from subduction zones is similar to or lower than that of hydrothermal solution from back-arc basins. 

J. Swinnen, J. A. van Veen, and R. Merckx, Rhizosphere carbon fluxes in field-grown spring wheat model calculations based on C partitioning after pufse-la-belling. Soil Biol. Biochem. 26 171 (1994). 

P. J. Kuikman, Quantification of carbon fluxes in grassland. Report Nr. 410 100 047 of the Dutch National Research Programme on Global Air Pollution and Climate Change. RIVM, Bilthoven, p. 52 (1996). 

J. A. van Veen, E. Liljeroth, L. J. A. Lekkerkert, and S. C. van de Geijn, Carbon fluxes in plant-soil systems at elevated atnio.spheric COi levels. Ecol. Appl. / 173 (1991). 

Cochran JK, Barnes C, Achman D, Hirschberg DJ (1995) Thorium-234/Uranium-238 disequilibrium as an indicator of scavenging rates and particulate organic carbon fluxes in the Northeast Water Polynya, Greenland. J Geophys Res 100(C3) 4399-4410... 

Where D is in cm yr and Depth in m. Although these two relationships explain some of the variability in D, it is clear that other environmental factors are also important, including sediment grain-size (Wheatcroft 1992) and the organic carbon flux (Trauth et al. 1997). 

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