ABSTRACT Major and trace element concentrations were measured in 96 samples of non-glaciated Wisconsin soils, as well as pH, organic carbon, and total carbon content. They represent surface soils intensively sampled in a randomized manner from a watershed (about 15 km2) in Dane County. Analytical methods employed are NAA (Neutron Activation Analysis), XRF (X-Ray Fluorescence), and ICP-MS (Inductively Coupled Plasma-Mass Spectrometry).

Element concentrations were determined in the total soils and in their corresponding clay-size fractions. This fraction was separated from the total soils based on Stoke's Law. We have found relative uniformity of both major and trace element concentrations in the clay-size fraction of these soils, which is independent from soil geographical and geohydrologic conditions, compared to the large variance in element concentrations in the total soils. Using element concentrations in the clay-size fraction reduces the variance of the concentrations values for most elements. This occurs because of the elimination of the dilution effect of quartz. Analysis of the clay-size fraction with a relative small number of samples is potentially the most useful approach for determining the background element concentrations over large geographic areas. These results are useful to find the occurrence of anthropogenic impacts on soil composition.