A METHOD OF STUDYING TRACE ELEMENTS IN SOIL FRACTIONS

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Abstract
Summary: A method is described for dividing soils into iron oxide, sand, silt, and clay fractions suitable for trace‐element analysis. The oxides are extracted under ultra‐violet light by ammonium oxalate (pH 3·3), which dissolves goethite and other iron oxides but not gibbsite or boehmite; it also extracts some soil organic matter and, probably, trace elements associated with it.Two horizons of two brown earths were analysed spectrochemically for Ba, Co, Cr, Cu, Ga, Mn, Ni, Pb, Sr, Ti, V, and Zr. The extracted oxides were the fractions richest in trace elements and contained large proportions of the total Co, Cu, Mn, Pb, and V. Except for Sr, Ti, and Zr, the amounts of trace elements in the sands were small and were distributed between the silicate‐mineral fractions in the order: sand > silt > clay. About half of the total Zr was in the sand fractions but appreciable amounts were in the extracts and clays. Increases of iron oxide and clay in the illuvial B horizons were paralleled by increases in the amounts of Ba, Cr, Co, Ga, Ni, and V.