ION EXCHANGE REMOVAL OF CARBONATES FROM SALINE CALCAREOUS SOILS PRIOR TO DETERMINATION OF CATION-EXCHANGE CAPACITY USING 89Sr++

Abstract

Ion exchange resins were used for removal of carbonates from saline calcareous soils prior to determination of cation-exchange capacity based on Sr++ retention. It was shown that CEC values measured as retained Sr++ in the soils pretreated with a mixed-bed resin were approximately equal to those obtained using the NH4OAc-method. Untreated samples, however, showed a Sr++ retention well over the measured CEC, mainly due to precipitation of Sr++ as carbonate. The NaOAc method gave somewhat higher CEC values than the Sr++ method, due probably to the higher pH (8.2). A comparison with the total amounts of exchangeable cations was also made. Use of an anion exchange resin alone for removal of carbonate ions, however, gave a Sr++ retention well below the measured CEC. This may have resulted from blocking of exchange sites by resin particles.