Carbonate exchange

In fhe envelope confermafion four of fhe carbon afoms are coplanar The fiflh car bon IS ouf of fhe plane of fhe ofher four There are fhree coplanar carbons m fhe half chair confermafion wifh one carbon atom displaced above fhaf plane and anofher below if In bofh fhe envelope and fhe half chair confermafions m plane and ouf of plane carbons exchange posifions rapidly Equihbrafion befween confermafions of cyclopenfane is very fasf and occurs af rafes similar to fhaf of rofafion abouf fhe carbon-carbon bond of efhane... 

In the envelope confonnation four of the caibon atoms aie coplanai. The fifth cai-bon is out of the plane of the other four. There aie thiee coplanai caibons in the half-chah confonnation, with one caibon atom displaced above that plane and another below it. In both the envelope and the half-chah confonnations, in-plane and out-of-plane carbons exchange positions rapidly. Equilibration between confonnations of cyclopentane is very fast and occurs at rates similar to that of rotation about the caibon-caibon bond of ethane. 

Budgets and cycles can be considered on very different spatial scales. In this book we concentrate on global, hemispheric and regional scales. The choice of a suitable scale (i.e. the size of the reservoirs), is determined by the goals of the analysis as well as by the homogeneity of the spatial distribution. For example, in carbon cycle models it is reasonable to consider the atmosphere as one reservoir (the concentration of CO2 in the atmosphere is fairly uniform). On the other hand, oceanic carbon content and carbon exchange processes exhibit large spatial variations and it is reasonable to separate the... 

Craig, S. G. (1998). The response of terrestrial carbon exchange and atmospheric CO2 concentrations to El Nino SST forcing. Report CM-94, Int. Meteorol. Inst, in Stockholm, Dept, of Meteorol., Stockholm Univ. 

Craig, S., Holmen, K. and Bjorkstrom, A. (1997). Net terrestrial carbon exchange from mass balance calculations an uncertainty estimate, Tellus, Ser. B, 49, 136-148. 

Hunt, E. R. Jr., Piper, S. C., Nemani, R., Keeling, C. D., Otto, R. D. and Running, S. W. (1996). Global net carbon exchange and intra-annual atmospheric CO2 concentrations predicted by an ecosystem process model and three-dimensional atmospheric transport model. Global Biogeochem. Cycles 10, 431-456. 

Kindermann, J., Wiirth, G., Kohlmaier, G. H. and Badeck, F.-W. (1996). Interannual variations of carbon exchange fluxes in terrestrial ecosystems. Global Biogeochem. Cycles 10, 737-755. 

Des Marais, D.J. (1985) Carbon exchange between the mantle and crust, and its effect upon the atmosphere Today compared to Archean time. In Sundquist, E.T. and Broecker, W.S. (eds.), The Carbon Cycle and Atmosphere CO2 Natural Variations Archean to Present. Washington, D.C. Am. Geophysical Union, pp. 602-611. 

Radiocarbon is uniformly distributed in the carbon exchange reservoir. 

Ammonium acetate at pH 5 Fine carbonates, exchangeable cations1 GSC... 

Another example of a 1,3-exoannular rearrangement, involving a 1,3-carbon exchange, is the base-catalyzed conversion of 2-amino-3-formylthiophenes into 3-cyanothiophenes [77JCR(S)294]. The reaction in-... 

Advantages of the carbonate-exchange technique are (1) experiments up to 1,400°C, (2) no problems associated with mineral solubility and (3) ease of mineral separation (reaction of carbonate with acid). Mineral fractionations derived from hydrothermal and carbonate exchange techniques are generally in good agreement except for fractionations involving quartz and calcite. A possible explanation is a salt effect in the quartz-water system, but no salt effect has been observed in the calcite-water system (Hu and Clayton 2003). 

In the case of oxide catalysts or alkali metal-doped oxide catalysts, basic surface sites can be generated by decarboxylation of a surface metal carbonate exchange of hydroxyl hydrogen ions by electropositive cations thermal dehydroxylation of the catalyst surface condensation of alkali metal particles on the surface and reaction of an alkali metal with an anion vacancy (AV) to give centers (e.g., Na + AV — Na + e ). 

Schimel, D. S., House, J. I., et al. 2001. Recent patterns and mechanisms of carbon exchange by terrestrial ecosystems. Nature, 414, 169-172. 

However, labeling the carbide ion with 13C2 reveals a complexity that is hidden in the reaction sequence. 16% of the reactant ions in equation 19 undergo carbon exchange in a... 

Trumbore, S. E., Gaudinski, J. B., Hanson, P. J., and Southon, J. R. (2002). Quantifying ecosystem-atmosphere carbon exchange with a 14C label. Eos, Trans. Am. Geophys. Union 83, 265-268. 

Atmosphere-ocean carbon exchange is much controlled by physical processes, including mixing of the surface and deep layers of the ocean across the thermo-cline. Biological processes favor the movement of carbon from the surface layer to deep layers and down to bottom sediments. The biological pump functions as a result of phytoplankton photosynthesis. 

Carbon exchange processes in the atmosphere-ocean system... 

CARBON EXCHANGE PROCESSES IN THE ATMOSPHERE-OCEAN SYSTEM... 

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