Die Fraktionierung der stabilen Isotope des Kohlenstoffs und des Sauerstoffs bei der Bildung von Calcit an der Erdoberfläche
| Autor: | G. Menschel, Jochen Hoefs, E. Usdowski |
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| Rok vydání: | 1982 |
| Předmět: |
Calcite
Supersaturation 010504 meteorology & atmospheric sciences General Chemical Engineering Inorganic chemistry Nucleation Fractionation 010502 geochemistry & geophysics 01 natural sciences Isotopes of oxygen chemistry.chemical_compound chemistry 13. Climate action Isotopes of carbon Calcium bicarbonate Carbonate 0105 earth and related environmental sciences |
| Zdroj: | Berichte der Bunsengesellschaft für physikalische Chemie. 86:1043-1046 |
| ISSN: | 0005-9021 |
| DOI: | 10.1002/bbpc.198200015 |
| Popis: | Calcite is not precipitated immediately from a supersaturated calcium bicarbonate solution because the initial activity of CO32− is small. Therefore, the solution degasses at first CO2 until at a critical value of ΔG of about – 1 kcal/mol calcite begins to nucleate. The fractionation of carbon isotopes between the dissolved carbonate and the atmosphere occurs under isotopic equilibrium. The precipitating calcite, however, exhibits substantial isotopic disequilibrium. The composition of the precipitated and the dissolved carbonate are virtually identical though they should differ by a Δ13C-value of about 2‰. Isotopic disequilibrium is also indicated by the oxygen isotopes: 18O-temperatures do not agree with the observed temperatures of calcite formation. |
| Databáze: | OpenAIRE |
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