Migration of ¹³⁷Cs Extracted from Contaminated Tea in Sandy Clay Soil

Abstract

The migration behavior of ¹³⁷Cs extracted from the contaminated tea at Chernobyl accident in sandy clay soil has been studied by batch and column experiments. Time dependent sorption behavior of ¹³⁷Cs extracted from the tea reaches equilibrium slower by 6.5 times than ¹³⁷Cs⁺ ions. However, the distribution coefficient of ¹³⁷Cs extracted from the tea for the sandy clay soil was higher than that of ¹³⁷Cs⁺ ions. These results indicate that the sorption of the ¹³⁷Cs attached to the organic materials dissolved from the tea on the sandy clay soil is slower than that of ¹³⁷Cs⁺ ions, and the ¹³⁷Cs attached to the organic materials have more affinity to the sandy clay soil than ¹³⁷Cs⁺ ions.

In the column experiments, most part of ¹³⁷Cs were adsorbed on the top of soil layer 0–10cm in depth and small amounts of ¹³⁷Cs were flowed out from the soil layer. The concentration profile at the top of soil layer of 0–10 cm is in agreement with that estimated by the dispersion- transport equation considered ion-exchange reaction indicating that the migration of ¹³⁷Cs extracted from the contaminated tea at the portion of high concentration is dominated by ion-exchange reaction. However, the concentration profile at deeper depth than 10cm is not fitted by estimation by such equation. Therefore, the mechanism other than ion-exchange dominates the migration of in the portion of low concentration.

KEYWORDS:

• radionuclide migration
• sorption
• cesium 137
• contaminated tea
• sandy clay soils
• time dependence
• depth distribution
• distribution coefficient
• migration rate
• retardation factor