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The carbonic acid system and calcite solubility in aqueous Na-K-Ca-Mg-Cl-SO[sub 4] solutions from 0 to 90[degrees]C

Journal Article · · Geochimica et Cosmochimica Acta; (United States)
OSTI ID:6014128
;  [1]
  1. Texas A M Univ., College Station (United States)

CO[sub 2] solubility, and the first and second stoichiometric dissociation constants of carbonic acid (K*[sub 1] and K*[sub 2]), have been determined in aqueous solutions containing Cl and SO[sub 4] salts of Na, K, Ca, and Mg over a wide range of ionic strength from 0 to 90[degrees]C at 0.1032 MPa (1 atm) pressure. Activity coefficients for CO[sub 2(aq)], HCO[sub 3][sup [minus]], and CO[sub 3][sup 2[minus]] ions were calculated from m[sub CO[sub 2]], K*[sub 1] and K*[sub 2]. These activity coefficients were then used to derive Pitzer parameters for the interaction between these carbonate species and other ions between 0 and 90[degrees]C. The resulting Pitzer model for the carbonic acid system was verified by its ability to accurately predict experimentally determined calcite solubility in brines from 0 to 90[degrees]C. However, calcite solubility measurements in complex brines initially supersaturated with respect to calcite indicate that Na[sup +], Mg[sup 2+], and SO[sub 4][sup 2[minus]] ions are probably incorporated into calcite lattice and significantly increase calcite solubility in brines. 50 refs., 8 figs., 7 tabs.

OSTI ID:
6014128
Journal Information:
Geochimica et Cosmochimica Acta; (United States), Journal Name: Geochimica et Cosmochimica Acta; (United States) Vol. 57:15; ISSN GCACAK; ISSN 0016-7037
Country of Publication:
United States
Language:
English