Migration behavior of radiostrontium and radiocesium in arid-region soil

Abstract

The time-dependent of the average migration, depths and migration rates of radiostrontium and radiocesium were experimentally determined in sandy soil in Kuwait. The study aimed to describe the behavior of these radionuclides in typical soil types in Kuwait. Custom-made large-diameter lysimeters (30 cm) were constructed to hold about 70 kg of undisturbed soil. The top surface soil was contaminated with known activity concentrations of 85Sr and 134Cs radionuclides. The topsoil was wetted with 1 L of water weekly using a rain simulator tool. Gamma scanning of the lysimeters in a step of 5 cm from three sides was performed at three measurement times by a high-resolution portable gamma spectrometry system. The vertical distribution pattern of 85Sr and 134Cs concentration exhibited an exponential trend. The average migration depth and migration rates were calculated, and 90% of the 85Sr and 134Cs were situated at 10.38 and 5.73 cm in the topsoil layer, respectively. The average vertical migration rate of 85Sr varied from 2.2 to 4.4 cm y−1, and 134Cs was from 0.3 to 0.9 cm y−1. It was demonstrated that the mobility of the 85 Sr and 134 Cs in the sandy soil could be attributed to the physicochemical properties of the radionuclide, in particular the distribution coefficient (Kd). The obtained results could be adopted by the regions of similar climatological conditions, especially, the gulf countries region when the radiological risk assessment of contaminated sites and dose estimation is required.