Simulating the process of radium desorption from coastal aquifer sediments by seawater

In this paper,leaching experiments were conducted with the aquifer sediments in the coast of Laizhou Bay to simulate the process of radium desorption.Within a typical range of SGD flow rates (0.02~0.30 cm/min),radium desorption (223Ra,224Ra and 226Ra) did not show much variation.Desorbed radium activity had positive linear relationship to salinity in the mixture of seawater and freshwater.However,when salinity was beyond salinity of seawater (e.g.,S=80),desorbed radium activity would approach the maximum platform.Compared the estimated activities of desorbed radium with in-situ measured values of pore water in the coast of Laizhou Bay,the results of 223Ra and 224Ra had good agreement while the results of in-situ measured 226Ra were less than estimate.It is likely because frequent desorption will decrease 226Ra activity before it can be regenerated from parent nuclide.This study should benefit better understanding of geochemical behavior of radium isotopes in aquifer sediments and offer new perspective of choosing SGD end-member.