Carbon balance

Fuel economy is measured usiag a carbon balance method calculation. The carbon content of the exhaust is calculated by adding up the carbon monoxide (qv), carbon dioxide (qv), and unbumed hydrocarbons (qv) concentrations. Then usiag the percent carbon ia the fuel, a volumetric fuel economy is calculated. If the heating value of the fuel is known, an energy specific fuel economy ia units such as km/MJ can be calculated as well. 

Reaction.s 1 through 15 con.stitute the cycle that lead.s to die formation of one equivalent of gluco.se. The enzyme catalyzing each step, a concise reaction, and die overall carbon balance is given. Numbers in parendieses show die numbers of carbon atoms in the substrate and product molecules. Prefix numbers indicate in a. stoichiometric fashion how many times each step is carried out in order to provide a balanced net reacdon. 

Carbon from the substrate glucose is converted into the carbon of the cells, phenylalanine, carbon dioxide and byproducts. Carbon balance calculations thus give us more understanding of the amount of carbon in glucose used for cell mass production, for synthesis of the wanted produd, maintenance energy and byproduct formation. 

Last but not least, one should check the inertness of the auxiliary electrodes in single-pellet arrangements, both under open and closed circuit conditions and, also, via the closure of the carbon balance, the appearance of coke deposition. This is especially important in systems with a variety of products (e.g. selective oxidations), where the exact value of selectivity towards specific products is of key interest. This in turn points out the importance of the use of a good analytical system and of its careful calibration. 

Carbon Balance in Northern Ecosystems and the Potential Effect of Carbon Dioxide Induced Climate Change Miller, P. C., Ed. CONF-8003118. National Technical Information Service Springfield, VA, 1981. 

Oceanic surface waters are efficiently stripped of nutrients by phytoplankton. If phytoplankton biomass was not reconverted into simple dissolved nutrients, the entire marine water column would be depleted in nutrients and growth would stop. But as we saw from the carbon balance presented earlier, more than 90% of the primary productivity is released back to the water column as a reverse RKR equation. This reverse reaction is called remineralization and is due to respiration. An important point is that while production via photosynthesis can only occur in surface waters, the remineralization by heterotrophic organisms can occur over the entire water column and in the underlying sediments. 

Fig. 11-12 Detrital carbon dynamics for the 0-20 cm layer of chernozem grassland soil. Carbon pools (kg C/ m ) and annual transfers (kg C/m per year) are indicated. Total profile content down to 20 cm is 10.4 kg C/m. (Reproduced with permission from W. H. Schlesinger (1977). Carbon balance in terrestrial detritus, Ann. Rev. Ecol. Syst. 8,51-81, Annual Reviews, Inc.)...

Pollard, D., Sitch, S. and Haxeltine, A. (1996). An integrated biosphere model of land surface processes, terrestrial carbon balance, and vegetation dynamics. Global Biogeochem. Cycles 10, 603-628. 

Schlesinger, W. H. (1977). Carbon balance in terrestrial detritus. Ann. Ecol. Syst. 8, 51-81. 

Equation (12.14) applies to all the elements that constitute a cell, but it is normally applied in the form of a carbon balance. The dominant terms in the balance are carbon in the cells, measured through Yxjs, and carbon in the primary metabolites—e.g., ethanol and CO2—measured through the Yp/s terms for these metabolites. 

Mooney, H.A. (1972). The carbon balance of plants. Annual Review of Ecology and Systematics, 3, 315 6. 

McCree, K.J., Kallsen, C.E. Richardson, S.G. (1984). Carbon balance of sorghum plants during osmotic adjustment to water stress. Plant Physiology, 76, 898-902. 

It is found that the CNF-HT has not catalytic activity for ODP. After oxidation, all the three samples show hi ly catalytic performances, which are shown in Fig.3. CNF-HL has the longest induction period among the three samples, and it has relatively low activity and propene selectivity at the beginning of the test. During the induction periods, the carbon balance exceeds 105% and then fall into 100 5%, which implies the CNF structure is stable and the surface chemistry of CNF reaches a dynamic equilibrium eventually. These results indicate that the catalytic activity of ODP can be attributed to the existence of surface oxygen complexes which are produced by oxidation. The highest propene yield(lS.96%) is achieve on CNF-HL at a 52.97% propane conversion. 

C]-anthracene was used to study its degradation in soil, and the formation of labeled metabolites that could be released only after alkaline hydrolysis (Richnow et al. 1998). It was possible to construct a carbon balance during the 599-d incubation, and to distinguish metabolically formed phthalate from indigenous phthalate in the soil. 

GL 18] [R 1] [P 19a-d] Errors in judging selectivity came from problems of closing the carbon balance, rather than from intrinsic analytical fluctuations and sampling errors [60, 62]. The formation of species in solution not identified by the analytics used (GC) could be ruled out instead, it was assumed that the loss of carbon is due to carbon deposition on the catalyst. The maximum loss of carbon amounted to about 20%, i.e. it was large. 

A. H. C. M. Schapendonk, P. Dijkstra, J. Groenwold, C. S. Pot, and S. C. Van De Geijn, Carbon balance and water use efficiency of frequently cut Loliuni perenne L. swards at elevated carbon dioxide. Global Change Biol. 5 207 (1997). 

The fluxes of POC determined by the " Th method applied to the world s oceans are summarized in Table 1. Where possible we have tabulated the ratio of Th-derived POC export to independent estimates of primary production. As noted above, this ratio, termed the 77i ratio (Buesseler 1998), is important in the euphotic zone carbon balance as it represents the leakage of POC out of the euphotic zone (The ThE ratio is so named to evoke the e ratio, which is defined as the ratio of POC flux measured with sediment traps to primary production). 

Figure 40.4. Selectivity to products in n-hexane ammoxidation as a function of the reaction temperature. Symbols selectivity to CO (X), CO2 ( ), iV-containing compounds ( , calculated with respect to n-hexane converted) and N2 (A, calculated with respect to ammonia converted). Carbon balance ( ). Catalyst Sn/V/Nb/Sb 1/0.2/1/3.

CO, while the earbon balance was between 40 and 60% for the catalyst with x=3, and lower than 40% for the catalyst with x=5. On the other hand, the selectivity to N2, formed by ammonia combustion, was much lower than that obtained with Sn/V/Nb/Sb 1/0.2/1/3. Therefore, in catalysts with the greater amount of Sn, most of N was contained in products that were not detected and that contributed to the relevant loss in carbon balance. 

In order to confirm the hypothesis made on the role of catalyst components, we carried out the reaction with a ratile-type V/Sb/0 catalyst, having V/Sb atomic ratio equal to 1/1 (Table 40.1). This catalyst was prepared with the conventional sluny method, and therefore had a surface area of 10 mVg, lower than that obtained with the Sn/V/Nb/Sb/0 catalysts prepared with the co-precipitation method. However, despite this difference, with V/Sb/0 the conversion of n-hexane was similar to that one obtained with Sn/V/Nb/Sb/0. This is shown in Figure 40.7, which reports the conversion of n-hexane, the selectivity to CO2, to / -containing compounds and the carbon balance as a function of the reaction temperature. 

Figure 40.7. Conversion of n-hexane ( ) and of ammonia (A), selectivity to CO + CO2 (X), to /V-containing compounds ( ) and carbon balance ( ) as a function of the reaction temperature. Catalyst V/Sb 1/1.

Figure 1 Reaction of nitrobenzene to form aniline. The C-HA term displays the carbon balance assuming all the HA is formed from a surface species.

Obviously, the first measure to think about could be the substitution of recycled fibre-based boxboard for foodstuff by virgin fibre-based material. The required amount of recycled fibre-based boxboard for foodstuff equals to 700,000 t/year in Germany [7]. For the substitution of the recycled fibre-based boxboard, it is simply assumed that the required virgin fibre-based board is produced totally from mechanical spruce pulp with a process yield of 97%. This would require in total additionally about 1.68 Mio m3 wood per year. The inventory study of the carbon balance of the German forests [8] indicates an average yearly wood growth of... 

In addition to knowing the total MTC solubility, it was important to determine the amount of methanol or other solvent retained by the MTC. This quantity, the incorporation ratio (R, gm incorporated organic material/gm coal-derived organic material), was determined by a carbon balance on the reaction. By assuming that any solvent retained in the dried MTC is pyridine-soluble, and subtracting it from the total dissolved material, the minimum solubility of the coal-derived material may be calculated. This quantity, the corrected solubility, is an indicator of the true solubilizing effect on the coal by the particular run conditions. ... 

The MDA experiments were performed in a continuous down-flow fixed bed reactor at 700°C, atmospheric pressure, and a space velocity of 1500 em3/(gcat h). Catalysts were pretreated in He flow at 700°C for 30 min before feeding a CH4 N2 mixture in a 9 1 voEvol ratio (N2 used as internal standard). Unreacted methane, the reference N2, and the reaction products were analyzed on line in a gas chromatograph (HP-GC6890) as detailed in [6]. Product selectivities are given on a carbon basis. The use of N2 as internal standard allows to obtain the amount of carbonaceous residues as the amount of carbon required to close the mass carbon balances to 100%. 

Deng BQ, Lu LC, Wang DQ (1990) The estimation of the microbial respiratory capacity and carbon balance of the soils in the forest ecosystem of Dinghushan Biosphere Reserve. Tropical and Subtropical Forest Ecosystem 6 41-46 (in Chinese with English abstract)... 

Malhi Y, Baldocchi DD, Jarvis PG (1999) The carbon balance of tropical, temperate and boreal forests. Plant Cell Environ 22 715-740... 

Houghton, R.A., Why are estimates of the terrestrial carbon balance so different Global Change Biol., 9(4), 500, 2003. 

This analytical procedure allowed the detection of C,-C49 hydrocarbons and c,-c22 alcohols. Carbon balance, calculated as moles of C contained in the reaction products divided by the moles of CO converted, always closed within 10%. 

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