Relationship between magnetization and trace elements content of Braziliansoils from different parent materials

Magnetic minerals are important in some Brazilian soils and they are a poss ible source of trace elements, especially in the highly weathered soils. Th e purpose of this investigation was thus to determine the trace element con tent in the magnetically separated sand, silt, and clay fractions from soil s of different lithological origins in order to test the hypothesis that hi gher levels of magnetization are directly proportional to the contents of t hese elements. To accomplish this objective, the samples were dissolved by concentrated HCl/HF/HClO4 acid attack, and the contents of Cd, Cr, Cu, Ni, Pb, Zn, Zr, and V were analyzed by atomic emission spectroscopy with induct ively coupled plasma (ICP-AES). The contents of trace elements in the total , magnetic and nonmagnetic sand, silt, and clay fractions were within the n ormal range presented by whole soils with the exception of Cd, which was hi gher. Magnetization (a,) of the total, magnetic and nonmagnetic soil fracti ons was evaluated with a special analytical balance. The sigma (s) values w ere higher for sand and lower for silt and clay fractions. The magnetically concentrated fractions gave results with variation in the same fashion but reaching higher values. The relationship between trace elements in soil fr actions and magnetization, studied by correlation analysis, gave higher and more significant correlation coefficients when a soil derived from itabiri te was excluded from the analysis. Because itabirite and mafic rocks have h igh magnetization, the correlation result demonstrates that there is a stro ngly significant association between magnetization and trace element conten ts for the sons derived from mafic rocks. Analysis of variance showed that there were significant differences between trace element contents of the ma gnetic compared with the nonmagnetic fractions of the soils derived from ma fic rocks, especially in their sand and silt fractions. Tukey's test for co mparison of means showed that mafic rocks have a higher content of trace el ements compared with the other parent materials. The results obtained confi rm the geochemical affinity of trace elements and the components of the mag netic fraction of the soils derived from the mafic rocks, mainly for sand a nd silt fractions, where higher contents of the investigated trace elements were observed.