The effect of the Ca2+ to activity ratio on spiral growth at the calcite surface

Larsen, Kirsten; Bechgaard, K.; Stipp, S. L. S.

doi:10.1016/j.gca.2009.12.028

Cited by 78 publications

(133 citation statements)

References 45 publications

Supporting

Mentioning

122

Contrasting

Unclassified

Order By: Relevance

“…4a, providing Fig 4b. This is consistent with the observation, previously reported in the literature for calcite growth, that the calcite step velocities and, more generally, the calcite growth rate decrease as the calcium-to-carbonate ratio increases (Nehrke et al, 2007;Larsen et al, 2010;Stack and Grantham, 2010;Bracco et al, 2012;Gebrehiwet et al, 2012). Additionally, the growth of 2D nuclei takes place at [Cd 2+ ] 0 P 0.025 mM (Fig.…”

Section: Growth Kinetics As a Function Of [Cd 2+ ]supporting

confidence: 93%

Kinetics and mechanisms of cadmium carbonate heteroepitaxial growth at the calcite (101¯4) surface

Xu¹,

Kovařík²,

Arey³

et al. 2014

Geochimica et Cosmochimica Acta

View full text Add to dashboard Cite

Elucidating the kinetics and mechanisms of heteroepitaxial nucleation and growth at mineral-water interfaces is essential to understanding surface reactivity in geochemical systems. In the present work, the formation of heteroepitaxial cadmium carbonate coatings at calcite-water interfaces was investigated by exposing calcite ð10 1 4Þ surfaces to Cd-bearing aqueous solutions. In situ atomic force microscopy (AFM) was employed as the primary technique. The AFM results indicate that the heteroepitaxial growth of cadmium carbonate proceeds via three different mechanisms depending on the initial supersaturation of the aqueous solution: advancement of existing steps, nucleation and growth of three-dimensional (3D) islands, and nucleation and spread of two-dimensional (2D) nuclei. The 3D islands and 2D nuclei exhibit different morphologies and growth kinetics. The effects of supersaturation on heteroepitaxial growth mechanisms can be interpreted in terms of the free energy barrier for nucleation. At low initial supersaturation, where 3D nucleation dominates, it is hypothesized, from the growth rate and morphology of the 3D islands observed with AFM, that the crystallization of the overgrowth follows a non-classical pathway involving the formation of a surface precursor that is not fully crystalline, whereas high supersaturation favors the formation of crystalline 2D nuclei whose morphology is based on the atomic structure of the calcite substrate. Cross-sectional transmission electron microscopy (TEM) images reveal that the atomic structure of the interface between the cadmium carbonate coating and calcite shows perfect, dislocation-free epitaxy.

show abstract

Section: Growth Kinetics As a Function Of [Cd 2+ ]supporting

confidence: 93%

Kinetics and mechanisms of cadmium carbonate heteroepitaxial growth at the calcite (101¯4) surface

Xu¹,

Kovařík²,

Arey³

et al. 2014

Geochimica et Cosmochimica Acta

View full text Add to dashboard Cite

show abstract

“…However, there are important differences among cations and anions that must be considered before extending the same conclusions to either oxygen or carbon isotope effects in calcite. In particular, Larsen et al (2010) proposed that the rate of Ca 2+ ion attachment to kink sites is likely limited by the rate of calcium desolvation, while the rate of carbonate ion attachment may be limited by the rate of calcium kink site dehydration. The dehydration frequency for Ca 2+ is about 10 8.2 s −1 whereas the dehydration frequency for CO 2− 3 is estimated to be in the range of 10 9 -10 10 s −1 (Nielsen, 1984).…”

Section: Interpretation Of Kinetic Fractionation Factorsmentioning

confidence: 99%

The influence of temperature, pH, and growth rate on the δ18O composition of inorganically precipitated calcite

Watkins

Hunt

Ryerson

et al. 2014

Earth and Planetary Science Letters

151

141

View full text Add to dashboard Cite

Editor: T.M. Harrison Keywords: calcite oxygen isotopes carbonic anhydrase paleothermometry kinetic effectsThe oxygen isotope composition of carbonate minerals varies with temperature as well as other environmental variables. For carbonates that precipitate slowly, under conditions that approach thermodynamic equilibrium, the temperature-dependence of 18 O uptake is the dominant signal and the measured 18 O content can be used as a paleotemperature proxy. In the more common case where carbonate minerals grow in a regime where they are not in isotopic equilibrium with their host solution, their oxygen isotope compositions are a convolution of multiple environmental variables. Here we present results from calcite growth experiments demonstrating the occurrence of large (>2h) non-equilibrium oxygen isotope effects under conditions relevant to biogenic calcite growth and many natural inorganic systems. We show that these non-equilibrium effects vary systematically with pH and crystal growth rate. An isotopic ion-by-ion crystal growth model quantifies the competing roles of temperature, pH, and growth rate, and provides a general description of calcite-water oxygen isotope fractionation under nonequilibrium conditions. The crystal growth model results show that (1) there are both equilibrium and kinetic contributions to calcite oxygen isotopes at biogenic growth rates, (2) calcite does not directly inherit the oxygen isotope composition of DIC even at fast growth rates, (3) there is a kinetically controlled variation of about 1h per pH unit between pH = 7.7 and 9.3 at constant growth rate for inorganic calcite as well as biogenic calcite, and (4) extreme light isotope enrichments in calcite in alkaline environments are likely due to disequilibrium among DIC species in aqueous solution. The model can be extended to 13 C uptake into carbonates as well as clumped isotopes but additional data are needed to constrain the kinetic fractionation factors for carbon isotopes. The experimental and model results constitute an important step in separating the relative influence of inorganic and biologic processes on isotopic fractionation and may aid the development of new paleoproxies based on nonequilibrium effects.Published by Elsevier B.V.

show abstract

“…the isotope fractionation model and its application to trace element partitioning described below. It is also noteworthy that recent studies have shown that k Ã f is dependent on the Ca 2+ /CO 3 2À ratio of the solution (Nehrke et al, 2007;Larsen et al, 2010), which is important for evaluating how the exchange flux R b relates to k Ã f .…”

Section: Equations For Surface Reaction Control Of Caco 3 Precipitationmentioning

confidence: 99%

Surface kinetic model for isotopic and trace element fractionation during precipitation of calcite from aqueous solutions

DePaolo

2011

Geochimica et Cosmochimica Acta

396

221

View full text Add to dashboard Cite

The effect of the Ca2+ to activity ratio on spiral growth at the calcite surface

Cited by 78 publications

References 45 publications

Kinetics and mechanisms of cadmium carbonate heteroepitaxial growth at the calcite (101¯4) surface

Kinetics and mechanisms of cadmium carbonate heteroepitaxial growth at the calcite (101¯4) surface

The influence of temperature, pH, and growth rate on the δ18O composition of inorganically precipitated calcite

Surface kinetic model for isotopic and trace element fractionation during precipitation of calcite from aqueous solutions

Contact Info

Product

Resources

About