Trace and major elemental analysis applications in the US Cooperative Soil Survey program

In response to national and international concerns about soil and water quality, personnel at the United States Department of Agriculture, Natural Resources Conservation Service (USDA-NRCS), Soil Survey Laboratory are developing standard procedures to determine trace metals in soils. This paper illustrates how trace metal studies, complemented by total analysis, increase the use and value of the modem National Cooperative Soil Survey. Examples include anthropogenic metal contamination (Pb, As, Hg, Cd, Cu, Zn) from a copper smelter in Deer Lodge Valley, Montana; nutrient deficiencies (Ca, N, P, K) and metal enrichment (Co, Cr, Fe, Ni) in serpentinitic soils in Klamath Mountains, Oregon; naturally-elevated metal concentration (As, Pb, Hg) in hydrothermally active soils in Yellowstone National Park; total P and Fe as measures of weathering, chelation, and translocation of parent material in chronosequence study on Mendenhall Glacier in southeast Alaska; and metal determinations (Ni, Cr, Pb, Cd, Zn, Cu) to provide interpretations for land use in New York City. Native metal concentrations in soils vary widely, determined by geologic origin and pedogenic processes. Studies of soils examine landscape distribution of soils and often include metal partitioning to determine specific fractions. Soils with high natural concentrations of metals or those contaminated through atmospheric deposition, waste application, or surface/ground water are common. Total and bioavailable metal concentrations must be determined because of their impact on land use. In general, knowledge limited to total metal concentrations can be misleading. Application and interpretation of trace metal data for soil surveys are method-dependent and caution must be exercised in its application in the soil survey.