Radiocesium Sorption-Desorption on Soil Clays and Clay-Organic Complexes

Measurements were made on the sorption-desorption of ¹³⁴Cs on soil clays and clay size aggregates of seven major soil orders of India. In general the clay sized aggregates showed lesser sorption of ¹³⁴Cs, the least being in Aridisols and Ultisols. Radiocesium sorption after removal of organic matter from the aggregates was significantly increased with increase in ¹³⁴Cs activity and the effect was marked at 25 kBq kg⁻¹. Removal of sesquioxides from clay aggregates leaving the clean clay samples drastically lowered the ¹³⁴Cs sorption and the magnitude of sorption was in conformity with the nature and content of clay mineral composition i.e. higher values being associated with Smectite and Mica as compared Kaolonites. 1.2 to 7.3% of the sorbed ¹³⁴Cs can be released from the samples and the order of effectiveness of the extractants was NH₄Cl > KCl> CaCl₂> water. The particle size of waste mica plays very important role and as the size decreases nearly 1.2 times higher ¹³⁴Cs was sorbed (76.67–96.00%). On an average about 4.78% of the sorbed ¹³⁴Cs could be desorbed from waste mica (2mm size) and NH₄Cl was found most effective extractant.