Migration Characteristics of~(85)Sr in Unsaturated Loess

From the results of two kinds of radionuclide migration tests in unsaturated loess conducted in the field and laboratory, it can be seen that loess has stronger sorption capacity for~85Sr; retardation coefficient, R_d, of~85Sr increases with water content θ rather than a constant; R_d derived according to conventional equation from distribution coefficient, k_d, obtained by batch in laboratory is more than the measured results; variation trend of the derived R_d with θ in unsaturated loess is contrary to the measured results; lateral concentration distribution variance, σ~2_y, is equivalent to longitudinal concentration distribution variance, σ~2_x, and can't be neglected under natural rainfall condition; rainfall rate affects obviously longitudinal expansion of~85Sr rather than lateral one; moreover, migration fast composition of~85Sr affects conservative level of assessment results. The characteristics mentioned above would considerably affect the predicted concentration of~85Sr at the concerned place towards lower reaches and hence affect considerably magnitude of potential risk to human.