Aragonite precipitation

Thompson G, Livingston HD (1970) Strontium and uranium concentrations in aragonite precipitated by some modem corals. Earth Planet Sci Lett 8 439-442 ThurberDL (1962) Anomalous in Nature. J Geophys Res 67 4518-4520... 

The importance of the interaction of organic compounds with calcium carbonate surfaces has long been recognized. It has been demonstrated that aragonite precipitation is inhibited by uncharacterized dissolved organic matter (Chave and Suess, 1967), and that humic and fulvic acids, and certain aromatic carboxylic acids, inhibit seeded aragonite precipitation from seawater (Berner et al., 1978). The selective adsorption of amino acids on carbonate substrates has received considerable attention. A preferential adsorption of aspartic acid has been shown from humic and fulvic acids and proteinaceous matter (Carter and Mitterer, 1978 Carter, 1978 Mitterer, 1971). 

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. 

Figure 7.21. A) Relative rates of calcite and aragonite precipitation in solutions with Mg Ca =1. B) Relative rates of calcite and aragonite precipitation in solutions with Ca Mg = 1 and containing dissolved sulfate. Note that in solutions without sulfate calcite precipitates faster, whereas in solutions containing sulfate aragonite precipitates faster. (After Walter, 1986.)...

Berner R.A., Westrich J.T., Graber R., Smith J. and Martens C.S. (1978) Inhibition of aragonite precipitation from supersaturated seawater A laboratory and field study. Amer. J. Sci. 278, 816-837. 

Zhong S. and Mucci A. (1989) Calcite and aragonite precipitation from seawater solutions of various salinities Precipitation rates and overgrowth compositions. Chem. Geol. (in press). 

V Holocene coral (this study) it inorganic aragonite precipitation (Chang 2002)... 

Aragonitic precipitated calcium carbonate 95-98 0.75-2.5 Steep/ narrow 6-18 Clustered needle aggregates low aspect ratio... 

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