ACID EXTRACTABLE RARE-EARTH ELEMENTS IN FLORIDA CITRUS SOILS AND TREES

To determine the levels of elements not usually included in soil analy ses, aqua regia extracts from 10 soils in eight locations throughout t he Florida citrus belt were analyzed for 14 rare earth elements (lanth anides), scandium, and yttrium with an ICP spectrophotometer. Leaves, bark, wood, and roots of citrus trees growing at two of the sampling l ocations, a fertilizer (14% N-1.7% P-11.6%K); and a dolomite sample we re also analyzed. Scandium(Sc), yttrium (Y), lanthanum (La), cerium (C e), praseodymium (Pr), neodymium (Nd), samarium (Sm), europium (Eu), g adolinium (Gd), terbium (Tb), dysprosium (Dy), and holmium (Ho) were f ound in the soil samples in amounts above detection limits varying fro m 0.002 to 0.017 mg/L. Cerium, La, and Nd were the elements present in the largest amounts. The levels showed no particular regional pattern and a great amount of variability, even between adjacent sites at the same location. A soil with a relatively high organic matter content a nd cation exchange capacity (CEC) (Hallandale soil at Indiantown in So uth Florida) had by far the highest rare earth content. Lanthanide lev els in the citrus tree tissues correlated with soil content, with the highest levels in the feeder roots (range 4.6 to 585. 1 mug/g). The fe rtilizer analyzed contained little, but dolomite appreciable amounts o r Sc, Y, La, Ce, Nd, Eu, Gd, and Dy.