Abstract
A technique using the relationship between the naturally occurring radionuclide tracers, 7Be and 210Pbxs, was used to differentiate eroded surface soils and channel-derived sediments in the fine suspended sediment loads of runoff events in five Conservation Effects Assessment Project watersheds. A simple two end-member mixing model was used to determine the relative contribution from each source. Results suggest that eroded surface soils were more prevalent in the suspended load early in a runoff event, but channel contributions dominated the suspended load at later stages. The method proved useful for multiple sites due to a constant proportion of the atmospheric deliveries of the two radionuclides globally. Use of only two radionuclide tracers simplifies the differentiation of sediment sources within a watershed but limits precision.
Footnotes
Christopher G. Wilson is a post-doctoral researcher with IIHR-Hydroscience and Engineering, University of Iowa, Iowa City, Iowa. Roger A. Kuhnle is a research hydraulic engineer at the National Sedimentation Lab, USDA Agricultural Research Service (ARS), Oxford, Mississippi. David D. Bosch is a research hydraulic engineer at the Southeast Watershed Research Lab, USDA ARS, Tifton, Georgia. Jean L. Steiner is a supervisory soil scientist and Pat J. Starks is a soil scientist at the Grazinglands Research Lab, USDA ARS, El Reno, Oklahoma. Mark D. Tomer is a soil scientist at the National Soil Tilth Lab, USDA ARS, Ames, Iowa. Glenn V. Wilson is a research hydrologist at the National Sedimentation Lab, USDA ARS.
- © 2008 by the Soil and Water Conservation Society
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