DETERMINATION OF RARE-EARTH ELEMENTS IN FERN LEAVES USING INSTRUMENTAL NEUTRON-ACTIVATION ANALYSIS

The lanthanides (REE) in 142 fern leaves collected from several sampli ng sites in Japan have been determined by neutron activation analysis, and the correlations between any two REEs in the logarithmic scatteri ng diagram were examined. The relationship was expressed by the genera l formula, Y=aX+b with a correlation coefficient R. A strong positive correlation was seen between any two REEs in the diagram with a regres sion coefficient and a correlation coefficient close to unity. However , between Eu or Tb and other REEs the relationship was split into two lines with the same correlation coefficient. From the intercept b, the relative abundance of the two elements was determined for each REE an d compared with those in hickory and tobacco leaves. These findings in dicated that the abundance pattern of fern leaves is suite different f rom those of hickory and tobacco leaves. Namely,the relative abundance of La and Ce was quite similar in the three plants, but the abundance of the other REEs (Nd, Sm, Gd, Dy and Lu) was considerably lower in f erns than in hickory and tobacco leaves. For Eu and Tb the higher valu es obtained in fern leaves coincided with those of the two plants.