Calcite growth kinetics: Modeling the effect of solution stoichiometry
2012 (English)In: Geochimica et Cosmochimica Acta, ISSN 0016-7037, E-ISSN 0016-1258, Vol. 77, 121-134 p.Article in journal (Refereed) Published
Until recently the influence of solution stoichiometry on calcite crystal growth kinetics has attracted little attention, despite the fact that in most aqueous environments calcite precipitates from non-stoichiometric solution. In order to account for the dependence of the calcite crystal growth rate on the cation to anion ratio in solution, we extend the growth model for binary symmetrical electrolyte crystals of Zhang and Nancollas (1998) by combining it with the surface complexation model for the chemical structure of the calcite-aqueous solution interface of Wolthers et al. (2008). To maintain crystal stoichiometry, the rate of attachment of calcium ions to step edges is assumed to equal the rate of attachment of carbonate plus bicarbonate ions. The model parameters are optimized by fitting the model to the step velocities obtained previously by atomic force microscopy (AFM, Teng et al., 2000; Stack and Grantham, 2010). A variable surface roughness factor is introduced in order to reconcile the new process-based growth model with bulk precipitation rates measured in seeded calcite growth experiments. For practical applications, we further present empirical parabolic rate equations fitted to bulk growth rates of calcite in common background electrolytes and in artificial seawater-type solutions. Both the process-based and empirical growth rate equations agree with measured calcite growth rates over broad ranges of ionic strength, pH, solution stoichiometry and degree of supersaturation.
Place, publisher, year, edition, pages
Elsevier, 2012. Vol. 77, 121-134 p.
Electrolyte Crystal-Growth, Solution Ca/P Ratio, Deep-Sea Sediments, Dissolution Kinetics, Octacalcium Phosphate, Surface-Chemistry, Constant Supersaturation, Complexation Model, Aqueous Solutions, Weathering Rates
IdentifiersURN: urn:nbn:se:kth:diva-90651DOI: 10.1016/j.gca.2011.11.003ISI: 000299010400009ScopusID: 2-s2.0-82655183836OAI: oai:DiVA.org:kth-90651DiVA: diva2:509922
QC 201203132012-03-142012-02-272015-07-21Bibliographically approved