Movement of Cs-137 in undisturbed calcareous soil and its extractability and association with soil particle size

Movement of Cs-137 was studied in undisturbed columns of sandy loam soil leached with irrigation water and 0.05 M KCl for 115 days using gamma spectrometry. At the end of leaching period, extraction of the retained Cs was performed by various extractants as well as its association with particle size of soil. It was found that the Cs concentration peak remained in the upper 1 cm of the soil columns although they were leached with 240 cm of either irrigation water or KCl. This indicates probably that most of the Cs radionuclides were irreversibly adsorbed on soil components. For 153 cm effluent passed through the columns, the Cs retained in the top 2 cm was 85.6% of total with KCl compared to 96.5% with irrigation water. The Cs front (9.25 MBq) advanced 0.9 and 4.5 cm under the application of 240 cm of irrigation water and KCl, respectively. The effectiveness of the extractants in removing Cs from soil previously leached with KCl was in the order: N H4 Cl> CsCl> KCl> Ca Cl2> D.H2 O. On the other hand, the order was KCl> N H4 Cl> CsCl> Ca Cl2> D.H2 o in soil leached with irrigation water. The percent of Cs associated with the clay fraction was 36.7, increased to 43.6 when H2 O2 was used for dispersion.3 tab., 2 fig