THE BEHAVIOR OF RARE-EARTH ELEMENTS AND Y DURING THE ROCK WEATHERING AND SOIL FORMATION IN THE RICANY GRANITE MASSIF, CENTRAL BOHEMIA

The geochemistry of rare-earth elements (REE) and yttrium has been stu died in the soil profile derived from a biotite granite in the area of 'Forest Brook Catchment' (FBC) near Ricany (Central Bohemia, the Czec h Republic). The comparison of the variation in the REE and Y concentr ations in the individual zones of the profile shows that total content of lanthanides depends on the grain size of the soil material. The ho rizons abundant in clay fraction (Gr(1), Gr(2)) contain five times mor e REEs than those with a predominance of silt and sand (G(0), Gr(3)). The chondrite-normalised soil La-Lu pattern is similar in all profile zones and it behaves as an almost smooth function of the REE ionic rad ii, or their atomic numbers, respectively. The bulk content of lanthan ides in soil is higher than that in the local partly weathered boulder s of the parent rocks (syeno- and monzogranite). The content of acid s oluble forms of REE (the portion of elements soluble in 0.1 M HNO3) in creases from the umbric horizon A towards the bottom of the profile. O ur results indicate that the mobile part of REE is leached and transpo rted to the lower part of the profile by acidic atmospheric precipitat ion. The REE distribution pattern of surface-and subsurface waters dra ining the terrain of the catchment confirms this consideration. (C) 19 98 Elsevier Science B.V.