Carbonate accumulation

Fig. 1. The relationship between the carbon accumulation and the NiO doping on Ti02 support in the methane decomposition at 998 K and GHSV of 2700 h at steady state.

Other applications of °Thxs profiling to assess accumulation rates of sedimentary components include carbonate accumulation in the Western Equatorial Atlantic (Rtihlemann et al. 1996) biogenic and terriginous particle accumulation on the Australian continental margin (Veeh et al. 2000) sedimentation rates in the North East Atlantic (McManus et al. 1998 Thomson et al. 1993 ) (Fig. 5) sedimentation rates during key... 

Temperature plays an important role in determining the amount and type of the carbon deposit. Generally during FTS at higher temperatures the amount of carbon deposited will tend to increase,30-31 but the case is often not so straightforward. An example of temperature dependence on the rate of carbon deposition and deactivation is the case of nickel CO hydrogenation catalysts, as studied by Bartholomew.56 At temperatures below 325°C the rate of surface carbidic carbon removal by hydrogenation exceeds that of its formation, so no carbon is deposited. However, above 325°C, surface carbidic carbon accumulates on the surface... 

Mayer, L.M. 1994. Surface area control of organic carbon accumulation in continental shelf sediments. Geochimica et Cosmochimica Acta 58 1271-1284. 

Mont = expanding mineral Kaol = kaolinite Sep = sepiolite Palyg = palygorskite Carbonate = secondary carbonate accumulation in the soil. Table modified from Vanden Heuvel (1966). 

Carbon formation is a very real problem, leading as it does to deposits (4,27). These may cause poor acceleration characteristics, uncertain ignition and spark-plug operation because of carbon accumulation in the dome areas, and decreased liner life caused by warpage resulting from uneven temperature profiles across the combustor liner when carbon deposits are present (37). 

Figure 8A. Rates of sulfur and carbon accumulation are highly correlated in surface sediments of 11 Swiss lakes (23). The solid line is the regression line and the dotted lines represent 95% confidence intervals. Variations in the carbon accumulation rates represent differences in trophic status and...

Hydrates are typically found where organic carbon accumulates rapidly, mainly in continental shelves and enclosed seas. These are biogenic hydrates (containing CH4, formed from bacterial methanogenesis). 

Gile LH, Peterson FF, Grossman RB (1966) Morphological and genetic sequences of carbonate accumulation in desert soils. Soil Sci 101 347-360... 

Amado T. J. C., Bayer, C., Conceiqao, P. C., Spagnollo, E., Costa de Campos, B.-H., and da Veiga, M. (2006). Potential of carbon accumulation in no-till soils with intensive use and cover crops in Southern Brazil. J. Environ. Qual. 35,1599-1607. 

Carrasco, J. J., Neff, J. C., and Harden, J. W. (2006). Modeling physical and biogeochemical controls over carbon accumulation in a boreal forest soil. J. Geophys. Res. Biogeosci. 111(G2). 

Raich, J. W., Russell, A. E.,Kitayama,K.,Parton,W. J., and Vitousek, P. M. (2006).Temperature influences carbon accumulation in moist tropical forests. Ecology 87(1), 76-87. 

Analysis of data on the carbon budget within the WCRP studies of GHG removal from the atmosphere in national parks in 13 states of the U.S.A. yielded interesting results (Kondratyev and Krapivin, 2005). According to these data, in these parks the amount of carbon accumulated in the top 20 cm layer of soil constituted 910 kg ha1 yr 1. Hence, over the whole territory of the program (5.6 million ha) the atmosphere was loosing annually 5.1 million tC. 

There were at least two possibilities in the conversion of the stearic acid to the CIO hydroxyacids they could be first hydroxylated and then chain shortened, or they could be first chain shortened and then hydroxylated. That the former occurs was demonstrated by two lines of evidence (1) mandibular glands chain shortened 18-hydroxy and 17-hydroxy stearic acid to the CIO acids and (2) both n-1 and n-2 hydroxyacids with more than 10 carbons accumulated when... 

The Oceanic Carbonate System and Calcium Carbonate Accumulation in Deep Sea Sediments... 

One of the most controversial areas of carbonate geochemistry has been the relation between calcium carbonate accumulation in deep sea sediments and the saturation state of the overlying water. The CCD, FL, R0, and ACD have been carefully mapped in many areas. However, with the exception of complete dissolution at the CCD and ACD, the extent of dissolution that has occurred in most sediments is difficult to determine. Consequently, it is generally not possible to make reasonably precise plots of percent dissolution versus depth. In addition, the analytical chemistry of the carbonate system (e.g., GEOSECS data) and constants used to calculate the saturation states of seawater have been a source of almost constant contention (see earlier discussions). Even our own calculations have resulted in differences for the saturation depth in the Atlantic of close to 1 km (e.g., Morse and Berner, 1979 this book). 

More recent calculations such as those in this book indicate substantially lower saturation depths. Those calculated here are plotted in Figure 4.21. The SD is generally about 1 km deeper than that presented by Berger (1977). Clearly the new SD is much deeper than the R0 and appears only loosely related to the FL. Indeed, in the equatorial eastern Atlantic Ocean, the FL is about 600 m shallower than the SD. If these new calculations are even close to correct, the long cherished idea of a "tight" relation between seawater chemistry and carbonate depositional facies must be reconsidered. However, the major control of calcium carbonate accumulation in deep sea sediments, with the exceptions of high latitude and continental slope sediments, generally remains the chemistry of the water. This fact is clearly shown by the differences between the accumulation of calcium carbonate in Atlantic and Pacific ocean sediments, and the major differences in the saturation states of their deep waters. 

Two major types of variability in the relationship between overlying water chemistry and carbonate accumulation in deep sea sediments occur. The first is the previously discussed relation of the saturation state of the water to the R0, FL and CCD. The second is the relative separation of these different sedimentary features. In some areas of the ocean these relations can be influenced by transitions in water masses having different chemical and hydrographic characteristics (e.g., Thunell, 1982), but in many areas of the ocean the only major variable influencing the saturation state over wide areas is pressure, which leads to a nearly uniform gradient in saturation state with respect to depth. 

A major benthic process, that had only casually been considered for its potential influence on carbonate accumulation in deep sea sediments, is the oxidation of organic matter. The general reaction for this process involving marine organic matter is (Emerson and Bender, 1981) ... 

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