Cadmium Sorption as Influenced by Carbonate Forms of Clay Fraction of Some Calcareous Soils in Al-Hassa

(Ibrahim bin Abdulrahman senses)

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Abstract

(2 - 0.2 um) clay fraction of the three representative soil profiles in Al-Hassa Oasis at Saudi Arabia. The results indicate that the total calcium carbonate (Ct) is high (9.40 - 28.10%) and relatively higher in fine than coarse clay. The calcite ranges from 0.35 to 9.55 %, Mg calcite is found to range from 0.00 to 10.20 % and the other carbonate varies 0.24 to 17.70 %. Mg calcite is relatively higher in the fine than the coarse clay fraction. Data of cadmium sorption by clay fraction indicate two populations of sites, (I and II) having different affinity for cadmium sorption, were present and fit the binary Langmuir equation. The constants related to the bonding energy in part I (K1I) were higher in fine clay than the coarse clay and correlated significantly with Mg-calcite content while the maximum adsorption values of part I were higher in the fine clay and correlated significantly with Mg-carbonate content. On the other hand, K1 and K2 for part II have no regular trend and no correlation with calcium carbonate forms.
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