The effects of magnesium-to-calcium ratios in artificial seawater, at different ionic products, upon the induction time, and the mineralogy of calcium carbonate: a laboratory study

Autor: Erwin Suess, R. M. Pytkowicz, Ahmed I. Rushdi, C. T. Chen
Rok vydání: 1992
Předmět:
Zdroj: Geologische Rundschau, 81 (2). pp. 571-578.
ISSN: 1437-3262
0016-7835
DOI: 10.1007/bf01828616
Popis: The effects of the Mg2+ ion concentration and the ionic products of carbonate upon the induction time for the onset of precipitation and the different mineralogies of calcium carbonates were studied. It was shown that Mg2+ ions delay the spontaneous precipitation of calcium carbonate from supersaturated solutions (e.g. seawater) with respect to calcium carbonate mineral to such an extent that only biogenic removal of skeletal calcium carbonate is possible from the open ocean. Low concentrations of magnesium ions in solution favor calcite formation while aragonite is formed at high magnesium concentrations. The mole% of MgCO3 in magnesian calcite increases with the increase of (Mg2+) in solution and with the increase of (CO32−) in the presence of (Mg2+) in solution. Therefore, one would expect that high Mg-calcite is formed in wormed coastal regions, where high temperature and or the increase of photosynthesis activities tend to expel CO2 and increase supersaturation, and low-magnesian calcite is favored in meteoric-vadose environment where low concentration of magnesium ions or in burial environment where respiration and oxidation is high and decrease supersaturation.
Databáze: OpenAIRE