Transformations of Carbon

In broad terms the decomposition of organic matter under anaerobic conditions is expected to be slower than nnder aerobic conditions becanse the free energy changes for the reactions involved are mnch smaller (Table 4.1 and Fignre 4.3). For example, for the aerobic decomposition of CH2O , 

AG° = -17.7kJmor at pH 7. Consequently the microbes mediating the decomposition derive less energy and produce fewer cells per unit of carbon metabolized. The accnmnlation of organic matter in marshes and peat bogs illns-trates this point. (Bnt note the rarity of tropical wetland soils with large organic matter contents, discnssed in Section 3.7.) 

The most striking difference between anaerobic and aerobic decomposition is in the nature of the end products. In aerobic decomposition the main prod-nets are CO2, NOs, 864 and resistant residues in anaerobic decomposition they are CO2, H2, CH4, N2, NH4+, H2S and various partially decomposed and humified residues. 

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Nickel and other transition metals function as solvent-catalysts for the transformation of carbon species into the diamond aHotrope. At temperatures high enough to melt the metal or metal—carbon mixture and at pressures high enough for diamond to be stable, diamond forms by what is probably an electronic mechanism (see Carbon, diamond-synthetic). 

Doong R-A, H-C Chiang (2005) Transformation of carbon tetrachloride by thiol reductants in the presence of quinone compounds. Environ Sci Technol 39 7460-7468. 

Workman SL Woods, YA Gorby, JK Fredrickson, and MJ Trnex (1997) Microbial reduction of vitamin B,2 by Shewanella alga strain BrY with snbseqnent transformation of carbon tetrachloride. Environ Sci Technol 31 2292-2297. 

Criddle CS, JT DeWitt, D Grbic-Galic, PL McCarty (1990) Transformation of carbon tetrachloride by Pseudomonas sp strain KC under denitrifying conditions. Appl Environ Microbiol 56 3240-3246. 

Lewis TA, RL Crawford (1995) Transformation of carbon tetrachloride via sulfur and oxygen substitution by Pseudomonas sp strain KC. J Bacteriol 177 2204-2208. 

The transformation of carbon dioxide into useful chemical derivatives is an attractive goal in chemistry. Electroreduction of Pd2(dppm)2Cl2 and Pd(dppm)Cl2 (dppm = bis(diphenylphosphino)-methane) in an aprotic medium under carbon dioxide produces Pd3 (//3-CO)(//-dppm)3.266... 

These anaerobic processes have been investigated under sewer conditions (Tanaka and Hvitved-Jacobsen, 1998, 1999, 2000 Hvitved-Jacobsen et al., 1999 Tanaka et al., 2000a, 2000b). The results from experiments in the laboratory, in a pilot sewer and under full-scale sewer conditions combined with theoretical considerations have provided knowledge on the anaerobic transformations of carbon that can be expressed conceptually (Figure 6.8). 

Tanaka, N., T. Hvitved-Jacobsen, and T. Horie (2000a), Transformations of carbon and sulfur wastewater components under aerobic-anaerobic transient conditions in sewer systems, Water Env. Res., 72(6), 651-664. 

This work was supported by JSPS (Nos. 16109001 and 17689001). M. A. expresses her thanks to the Grant-in-Aid for Scientific Research on Priority Areas, Advanced Molecular Transformation of Carbon Resources from MEXT (No. 18037005). 

The transformation of carbon dioxide and hydrogen into methane by methanogenic archaea of the Methanosarcina species is represented by Eq. 1 ... 

A project at the University of Arizona (FEDRIP 1996) will study microbial dehalogenation of several compounds, including chloroform. A major part of the study will focus on the facultative anaerobic bacteria Shewanella putrefaciens sp., which is known to catalyze the transformation of carbon tetrachloride to chloroform and other as yet unidentified products. The organic substrates will also contain metals. It is hoped that the end-products from the biochemical treatment can be subjected to a photolytic finishing process that will completely mineralize any remaining halogenated compounds. 

Kriegman-King, M.R. and Reinhard, M. Transformation of carbon tetrachloride in the presence of sulfide, biotite. and vermiculite. Environ. Sci. TechnoL, 26(ll) 2198-2206, 1992. 

Nickerson WJ. 1956. Transformation of carbon compounds by microorganisms. Ind Eng Chem 48 1141-1142. 

Criddle CS, DeWitt JT, Grbic-Galic D, et al. 1990. Transformation of carbon tetrachloride by pseudomonas sp. strain KC under denitrification conditions. AppI Environ Microbiol 56 3240- 3246. 

It is about an active mechanism depending on the Na+-K+-ATPase enzyme located in the lateral plasma membrane of the endothelial cells. It enables the penetration of potassium into the cell against the excretion of sodium into the aqueous humor. Then this latter becomes hypertonic in comparison with the stroma and thus drains the water. In normal conditions, the pump can adapt to the physiological needs. Actually, the moves of the sodium ion are relative to those of the bicarbonate ion (responsible for the negative polarization of the back side of the endothelial cell) and to the pH variation. And yet, the bicarbonate comes from the aqueous humor and from the intracellular transformation of carbon dioxide and water by carbonic anhydrase. All of this shows the good functioning of the pumps depends on the integrity of the plasma... 

Kriegman-King, M. R., and M. Reinhard, Transformation of carbon tetrachloride by pyrite in aqueous solution , Environ. Sci. Technol., 28, 692-700 (1994). 

More recently the transformation of carbon-supported Pt colloids of approximately 1 nm diameter into Pt alloys has been reported, which seems to yield an even better catalyst, since the alloy particles—although coarser than the initial Pt particles—show improved catalytic activity and stability. It is not unlikely that from these alloys by in-situ oxidation transition-metal platinum bronzes like NLPt304 are formed, being the catalysts proper. 

Chiu, P.C. and M. Reinhard. 1995. Metallocoenzyme mediated reductive transformation of carbon tetrachloride in titanium(III) citrate aqueous solution. Environ. Sci. Technol. 29, 595-603. 

Pare, T., Dinel, H., Schnitzer M., and Dumontet, S. (1998). Transformations of carbon and nitrogen during composting of animal manure and shredded paper. Biol. Fertil. Soils 26, 173-178. 

The efficiency of the carbon sink on land depends on the transformation of carbon compounds into forms characterized by having a long lifetime (wood, soil). An enhancement of carbon sink due to increasing NPP can manifest itself only as a result of the inertia of these slow reservoirs of carbon in the process of land cultivation. At present, global pure production in agriculture is estimated at 8 109 tCyr-1. 

Eutrophication reduces the 02 content and increases the presence of NH4 in freshwater. These changes can affect the processes of transformation of carbon and nitrogen giving CH4 and N20, which are emitted to the atmosphere. Liikanen and Martikainen (2003) studied these processes in Finland and showed that in the case of a eutrophicated lake the bottom sediment can emit up to 7.9 mmol m-2 da-1 of CH4 and 7.6 pmol m 2 da 1 of N20, with oxygen being a key factor in the regulation of these fluxes through N03 formation. 

Chapter 5 deals with transformations of carbon-carbon 7C-bonds into a variety of functional groups. 

Sakakura T, Choi J-C, Yasuda H (2007) Transformation of carbon dioxide. Chem Rev 107(6) 2365-2387... 

Mikkelsen M, Jorgensen M, Krebs FC (2010) The teraton challenge. A review of fixation and transformation of carbon dioxide. Energy Environ Sci 3(1) 43—81... 

Cokoja M, Bruckmeier C, Rieger B et al (2011) Transformation of carbon dioxide with homogeneous transition-metal catalysts a molecular solution to a global challenge Angew Chem Int Ed 50(37) 8510-8537... 

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