The uptake behavior of rare earth elements (REEs) under pot conditions using deionized water and a REE fertilizer solution as the culture media as well as the distribution of REEs in rice proteins were studied. The uptake of REEs in rice seeds increased dramatically after a lag period of approximately three days. Roots can accumulate a much higher content of REEs than germs and the resting seeds. The REE content in each water-soluble (albumin) and salt-soluble (globulin) component of the rice seeds accounted for 5±8% and 4±6% of the total REEs, respectively. However, there are less than 1.5% of the total REEs were found in the alcohol-soluble (prolamin) and acetic acid-soluble (glutelin) components. The high performance liquid chromatography (HPLC) in the gel permeation and the reserved-phase were used to monitor changes in the molecular weight distribution changes of the soluble proteins of rice seeds during germination after having been cultured in the same solution for seven days. No changes occurred in the prolamin, while a slight change occurred in the albumin, globulin and glutelin. Fractionation of the albumin of rice seeds cultured in a REE fertilizer solution on the Sephadex G-100 column indicated that REEs, especially Ce, La, Pr and Nd, were associated mainly with biological compounds of a molecular weight between 10,000 and 12,000. Ó
Study on desorption kinetics of Y, La, and Ce from soils is of importance because it relates to the bioavailability and potential toxicity of rare‐earth elements. In the present study, a column‐flow method and three models (first‐order, two site first‐order, and log‐normal distribution first‐order kinetics models) were used to describe the desorption kinetics of Y, La, and Ce from four Chinese soils with different physicochemical properties. A high desorption percentage of Y (87.1–96.6%), La (89.9–98.5%), and Ce (57.6–96.4%) from Yingtan soil was attributed to the low soil pH 5.43 and low organic matter of 1.53%. In contrast, a low percentage of Y (27.5–45.7%), La (27.6–53.6%), and Ce (1.09–50.8%) sorbed by Beijing, Tongjiang, and Haerbin soils desorbed probably because of the higher soil pH values of 8.24, 7.16, 7.23, and increased organic matter (36.4%) in Haerbin soil. The results also suggest that the first‐order kinetics model did not offer an acceptable description of the data (R2 < 0.90). However, excellent agreements were achieved between the experimental data and fits to the latter two kinetic models (R2 > 0.99). The parameters derived from the kinetic equations indicated that increasing the initial sorption period from 1 to 20 wk could lead to a strong binding of rare‐earth elements, resulting in slower desorption.
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