同位素示踪法测定稀土在土壤中的吸附、解吸和扩散

Determination of RE Adsorption, Desorption, and Diffusion by Isotopic Tracer

对９种不同性质土壤测定结果表明，ＲＥ的吸附或解吸均与Ｌａｎｇｍｕｉｒ方程有极好的拟合性。土壤ＲＥ吸附容量在１．５～１５ｍｇ／ｇ之间，它与土壤中伊利石的相对含量呈明显正相关。土壤ＲＥ解吸量与吸附量之间呈显著指数曲线关系，曲线转折点的ＲＥ吸附量称为土壤特征吸附量，以它表征ＲＥ在土壤中运移难易，比土壤吸附容量表征更有意义。ＲＥ在土壤中的扩散能力很弱，其扩散系数比土壤中一般离子小一个数量级。

Data of RE adsorption or desorption from 9 type of investigated soil fit well in with Langmuir Equation. Obvious positive correlation was found between soil RE absorbing capacity (1. 5～ 15 mg/g for the 9 soils) and illite. The amount of RE desorbed appears exponential relatonship to that of sorbed. The turning point of the curve is called 'Characteristic adsorption quantity' so as to describe the change. This sorption relation of RE-illite is of higher significance than that of RE-soil. Diffusion of RE in soils proved to be very weak. The diffusion ceofficient was obtained one order of mignitude lower than those of the ordinary ions in soils.