Distribution of Radionuclides in the Leachates for Several Rock Types at Different Time Intervals

In the present study, the behavior of the different isotopes activity concentrations for three different rock samples (siltstone, shale and sandy dolomite) as well as in the different leachates of these rocks were studied at different time intervals, using a HP-Ge spectrometer. The activity concentration of U for the leachates gradually increases while that for U is nearly constant. The results revealed that the solubility gradually decrease from U to U, U and Ra respectively. The reason for the higher U concentrations in leachates is due to αrecoil process which enhances the mobilization and solubility of the decay product of U relative to the parent (U).Also theU activity concentration percent in leachates to that in origin samples increases towards equilibrium state due to the growth of the Th. It is noticed that theU% of siltstone and shale are very close and higher compared to dolomite which is much less in spite of the higher activity of the dolomite rock sample. The ratio (U/U) for the first measurement of the leachates was considered at zero time as 1.09±0.17, 1.4±0.21 and 1.6±0.18 for siltstone, shale and sandy dolomite respectively. The enrichment of U is accordingly related to the crystal damage and leaching, which are the main mechanisms for the (U/U) disequilibrium. The variations in the activity ratio (U/U ) are related to the increase in the activity concentration of U with time and also to very little variations in U.The solubility for Ra, Th, and K are very low and mainly remain in the residuals. [A. Nada. Distribution of Radionuclides in the Leachates for Several Rock Types at Different Time Intervals. Life Sci J 2012; 9(4):241-248]. (ISSN: 1097-8135). http://www.lifesciencesite.com. 35