METAL CONCENTRATIONS OF IOWA'S TOPSOIL

The Iowa DNR is taking part in the USGS National Geochemical Survey (NGS) to produce a body of geochemical data for the United States based primarily on stream sediments, analyzed using a consistent set of methods. These data will compose a complete, national-scale geochemical coverage of the US, and will enable construction of geochemical maps, refine estimates of baseline concentrations of chemical elements in the sampled media, and provide context for a wide variety of studies in the geological and environmental sciences. The study reported here involved statistical analysis of soil samples collected from the top 48 inches of soil at 357 sites throughout Iowa. Two samples from each site were analyzed to produce concentrations of metals from a top horizon of 12 inches and a lower horizon of 12-48 inches. Metal concentrations were determined by ICP 40-element acid-dissolution, and atomic-absorption methods. A total of 44 elemental metal concentrations were statistically analyzed through basic mean and median calculations related to their geographic position within the major landform regions of Iowa. Metal concentrations of As, Ba, Fe, Ce, Mg, and Ca show potential correlations with three of Iowa's major landform regions.