Chapter 5: Survey of Experimental Information on Cation Exchange in Soil Systems

Modeling the competition between solid solution formation and cation exchange on the retardation of aqueous radium in an idealized bentonite column

“…In this work, the equilibrium exchange constant for Ra was assumed to be the same as for Sr. To test the sensitivity of this parameter, we decreased the stability of the exchange component Ra 1/2 Mont, by increasing its G°2 98 value 7000 J/mol (17 times weaker K G ). This correction is well above the range of selectivity coefficients for alkali earth cations on montmorillonite (Benson, 1982;Bruggenwert and Kamphorst, 1979). However, the model result basically remains the same and the trend in Fig.…”

Potassium-calcium exchange in five Ap soils from paddy fields and its effect on potassium concentration in soil solution

“…Similar experiments on K-NH4 exchange equilibria showed that these two cations also behaved quite sirnilarly (Bruggenwert and Kamphorst 1979). Analyses on both the exchangeable cation composition and soil solution composition of submerged soils (Tsuchiya et al 1986) showed that the selectivity coefficient of Ca-Fe (II) exchange equilibria was in a relatively narrow range of 0.5 to 1.2.…”

“…However, numbers of experiments on Ca-Mg exchange equilibrium on soils and clay minerals showed that there was only a small difference between their selectivity for Ca and that for Mg (Bruggenwert and Kamphorst 1979;Odahara and Wada 1992). Similar experiments on K-NH4 exchange equilibria showed that these two cations also behaved quite sirnilarly (Bruggenwert and Kamphorst 1979).…”

“…soils as seen from a compilation by Bruggenwert and Kamphorst (1979) and a review by Goulding (1983). Recently, Levy et al (1988) have studied K-Ca exchange on kaolinite and kaolinitic soils.…”

Characterization of reactive tracers for C-wells field experiments 1: Electrostatic sorption mechanism, lithium

“…This lack of success may be because lithium is not an element of concern in agricultural production and is not considered a contaminant according to environmental regulations. Two references (21,22) Adsorption of lithium does not seem to involve a strong surface interaction. For instance, some studies strongly suggest that lithium shows a lower preference for natural ion exchangers than do the rest of alkali cations, namely, sodium (Na T ), potassium (K ), rubidium (Rb ), and cesium (Cs + ) (25).…”