Kinetic and thermodynamic factors controlling the distribution of SO32− and Na+ in calcites and selected aragonites

The role of sulfate groups in controlling CaCO3 polymorphism

“…The driving force for the solvent-mediated transformation of aragonite into calcite would be determined by the difference in solubility between the original pure aragonite phase (the seeds introduced in the system) and a calcite that would nucleate from the sulfate-bearing aqueous solution and presumably incorporate some sulfate in its structure. As previously discussed, the solubility of such a sulfatebearing calcite (DE cal > 0) would be very close to that of pure aragonite, or even higher if the sulfate content of the calcite is significant (Busenberg and Plummer, 1985). Under these conditions, the driving force for the transformation would be very small to negligible.…”

“…They found that the solubility of calcites containing up to % 1 mole% SO 4 2À is slightly less to equally soluble than pure calcite. Conversely, calcites with higher SO 4 2À contents (DE cal > 0) are more soluble than pure calcite, whereas calcites containing more than 3 mole% SO 4 2À are more soluble than pure aragonite (Busenberg and Plummer, 1985). In contrast to the calcite behavior, according to the lattice energy calculations, the incorporation of sulfate into vaterite is expected (DE vat < 0) to decrease its solubility.…”

“…5) are also consistent with the incorporation of sulfate ions in their structure. In the case of calcite, the formation of a limited Ca(CO 3 ,SO 4 ) solid solution was proposed early on by Busenberg and Plummer (1985) on the basis of the XRD shift of d-spacings as a function of calcite sulfate content. Recently, the substitution of sulfate for carbonate groups in the calcite structure was corroborated by the application of synchrotron radiation-based techniques (Frisia et al, 2005).…”

“…Busenberg and Plummer (1985) experimentally measured the solubility of calcites containing different amounts of SO 4 2À . They found that the solubility of calcites containing up to % 1 mole% SO 4 2À is slightly less to equally soluble than pure calcite.…”

Na/Ca variability in coral skeletons

“…The slab was ultrasonically cleaned in distilled/ deionized water (DDW) and dried, then X-rayed. The Xradiography revealed coral skeletal growth patterns and Element/Ca ratio General range (mmol/mol) References Na/Ca 15−24 Amiel et al (1973), Land and Hoops (1973), Polyakov and Krasnov (1976), Swart (1981), Oomori et al (1982), Busenberg and Plummer (1985), Kitano (1990), Bar-Matthews et al (1993), Tsukamoto and Tsukamoto (1995), Mitsuguchi et al (2001), Ramos et al (2004) Sr/Ca 8.0−10.0 Weber (1973), Polyakov and Krasnov (1976), Goreau (1977), Smith et al (1979), Oomori et al (1982), Schneider and Smith (1982), Beck et al (1992), de Villiers et al (1994, Fallon et al (1999Fallon et al ( , 2003, Gagan et al S/Ca 4.0−10.0 Tokuyama et al (1972), Oomori et al (1982), Busenberg and Plummer (1985), Kitano (1990), Bar-Matthews et al (1993), Tsukamoto and Tsukamoto (1995) F/Ca 3.0−7.0 Carpenter (1969), Ohde et al (1978), Ohde and Ramos (2004), Ramos et al (2005) Mg/Ca 2.5−6.5 Chave (1954), Weber (1974), Goreau (1977), Oomori et al (1982), Mitsuguchi et al (1996Mitsuguchi et al ( , 2001Mitsuguchi et al ( , 2003Mitsuguchi et al ( , 2008, Sinclair et al (1998), Fallon et ...…”