A Statistical Evaluation of the Inter‐relationships Between Particle‐size Fractions, Free Iron Oxide, and Trace Elements 1

Summary A statistical approach was adopted to study the association between particle‐size fractions and trace elements in soil, because conventional studies on the subject usually involve chemical methods of fractionation, which may lead to loss and upsets in natural distribution patterns. The results showed that both total and extractable contents of Zn, Al, Cu, Mn, Pb, and Fe are bound up either in clay or silt fractions, although variations as to the particular particle‐size diameter range did occur among the different elements. An attempt to resolve these relationships fitting a linear mathematical function, y = a+bx , based on the statistical association of individual particle‐size fractions with particular trace elements, gave satisfactory results. There was no evidence to indicate that certain size fractions could mobilize trace elements by virtue of their abundance in these soils. There was convincing statistical proof to show that amorphous Fe 2 O 2 , possibly by way of surface coating of finer particles, may retain a large proportion of the trace elements investigated.