Forty years of 90Sr in situ migration: importance of soil characterization in modeling transport phenomena

In 1960 experiments were carried out on the transfer of 90Sr between soil, grapes and wine. The experiments were conducted in situ on a piece of land limited by two control strips. The 90Sr migration over the last 40 years was studied by performing radiological and physico-chemical characterizations of the soil on eight 70 cm deep cores. The vertical migration modeling of 90Sr required the definition of a triple layer conceptual model integrating the rainwater infiltration at constant flux as the only external factor of influence. Afterwards the importance of a detailed soil characterization for modeling was discussed and satisfactory simulation of the 90Sr vertical transport was obtained and showed a calculated migration rate of about 1.0 cm year−1 in full agreement with the in situ measured values. The discussion was regarding some of the key parameters such as granulometry, organic matter content (in the Van Genuchten parameter determination), Kd and the efficient rainwater infiltration. Besides the experimental data, simplifying assumptions in modeling such as water–soil redistribution calculation and factual discontinuities in conceptual model were examined.