Geochemical behavior of rare earth elements, U, and Th during weathering of basaltic glass

Long-term migration behavior of rare earth elements (REE) as a chemical analogue of Am and Cm, together with U and Th, was investigated based upon chemical analyses of Andosol and Loam in Kanto area, central Japan. Basaltic glass has been weathered to clay minerals and iron oxyhydroxides in Andosol and Loam. The order of mobility of the elements during the chemical weathering of Andosol is alkali, alkali earth elements > REE > U, Th. The release rate of these elements is smaller in Loam underlying Andosol than in Andosol. Maximum release rate of REE, U and Th from the basaltic glass in Andosol during 3000 years is estimated to be ca. 50%, 30% and 30%, respectively. However, REE, U and Th released from the basaltic glass migrated downward and accumulated in Loam, suggesting that REE, U and Th were not removed from Andosol + Loam system for a long period. (author)