Calcium carbonate natural organic matter

Mitterer R.M. and Cunningham R Jr. (1985) The interaction of natural organic matter with grains surfaces Implications for calcium carbonate precipitation. In Carbonate Cements (eds. N. Schneidermann and P.M. Harris), pp. 17-31. Soc. Econom. Paleontoligists and Mineralogists, Tulsa, OK. 

Fusion with Alkali and Other Agents. Calcium peroxide was added portionwise to the fusion mixture at 180°C. but did not change materially the nature of the yields or reaction products. It should be noted that, in these fusions, total recovery of solids was quite low owing to large conversion of organic matter to carbon dioxide. 

The most complete study of the inhibition of calcium carbonate precipitation by organic matter was carried out by Berner et al. (1978), where primary concern was the lack of carbonate precipitation from supersaturated seawater. Both synthetic organic compounds and organic-rich pore waters from Long Island Sound were used to measure the inhibition of aragonite precipitation. Natural marine humic substances and certain aromatic acids were found to be the strongest inhibitors. The rate of precipitation in pore waters was also found to be strongly inhibited. 

PrecipUaHon processes are only adapted to hard waters, and are de s ed to separate the excess of calcium salt, and at the same time a considerable quantity of organic matter, which is mechanically carried down with the preeijiitate. e method usually followed consists in the addition of lime (in the form of lime-water), in just Bofi cieut ontity to neutralize the excess of carbon dioxide present w the water, llie added lime, together with the calcium salt naturally present in the -water, is then precipitated, except that small portion of calcium carbonate which the water, freed from carbon dioxide, is capable of dissolving. To determine when sufficient lime-water has been added, take a sample from time to time during the addition, and test it with solution of silver nitrate until a brown precipitate is formed. At this point cease the addition of lime-water and mix the limed water with further portions of the haid water, until a sample, treated with silver-nitrate solution, gives a yellowish in place of a brown color. 

The three examples of the effects of pedochemical weathering on the surface structures in soil clays just described illustrate the complexity of the reactive solid materials in natural soils. To these examples can be added many others, including the formation of iron oxyhydroxide or calcium carbonate coatings on the external surfaces (as opposed to interlayer surfaces) of phyllosilicates, the development of thick envelopes of colloidal organic matter on aggregates of metal oxides and aluminosilicates, and the... 

The reduced mobility of radium in comparison with uranium is explained by the solubility difference between the two elements, which occur in nature as sulphates and carbonates at 18°C radium sulphate = 1.410" g/1 uranyl sulphate = 205 g/1 radium carbonate is insoluble and uranyl carbonate = 60g/l. With the acidity and alkalinity of water, however, radium solubility changes. The radium content of water also depends on the salt concentration of certain elements—mainly alkaline chloride (radium replaces sodium). Radium precipitates with complexes of barium (S04Ba) and with calcium carbonates (travertine). Radium is also fixed by clay, organic matter, iron and manganese hydroxides. 

Boron can be extracted from natural or synthetic calcium carbonate (or other geologic materials) before analysis by mass spectrometry. The extraction method depends on the analytical technique to be used. For any method, natural samples (typically foraminifera, a single-celled marine invertebrate whose shells accumulate in ocean sediments) must be cleaned of organic matter. This is... 

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