The Effects of Human Activity versus Natural Processes on U.S. Soil

Suzanne Nicholson, USGS, collecting soil at one of the sites in New Jersey, on the coast of the Atlantic Ocean just south of Atlantic City. The USGS is completing a low-density soil geochemical and mineralogical survey for the conterminous U.S., which is needed as baseline data for environmental investigations and to understand the large-scale processes dominating the distribution of chemical elements at the earth's surface. Current data reveal coherent, continental- to regional-scale patterns that depend on underlying soil parent materials, soil age, land type/land use, and climate. Human-induced modifications to soil geochemistry related to current and historic industrial and agricultural activities are recognized by comparing element concentrations in surface soils to deeper soils at individual sites. However, regional enrichments of some metals of environmental concern resulting from mineralization by natural geologic process can be as high (or even higher) than enrichments from anthropogenic contamination.