Geochemical Variations in Four Residual Soils

Abstract

Variations in concentrations of Si, Al, Fe, Mg, Ca, Na, K, and Ti (as oxides) and Ba, Co, Cr, Cu, Ga, Mn, Ni, Pb, Sc, Sr, V, Zn, and Zr were determined by the mutual-standard method of spectrochemical analysis on the total soil and parent-rock samples, separated sand, silt, and clay fractions, and acetic acid leachates of soils developed from granodiorite (Wyoming), basalt (Colorado), granite (Missouri), and metamorphosed andesite (North Carolina). Intraplate precision is ±7.5 per cent; interplate precision is ±28 per cent. Particle-size distribution, the mineralogy of each size fraction and measurements of -H2O, pH, Eh, soluble salts, free iron oxide, organic matter, and exchange capacity are related to composition by graphical and statistical methods. These conclusions are presented for the four soils: 1.Enrichment or depletion of most trace elements is directly proportional to the amount of clay and silt produced by weathering. 2.The largest concentration changes occur across the parent rock-soil inter...