Monday, 10 July 2006 - 4:00 PM

Loss of Dissolved Organic Carbon During Erosion Events.

Diane E. Stott, E.A. Warnemuende, S.J. Livingston, and C. Huang. USDA-ARS National Soil Erosion Research Laboratory, 275 S Russell St, West Lafayette, IN 47907-2077

Transport of carbon from hillslopes to adjacent ditches, streams and watersheds can represent a significant loss of C. While carbon associated with eroding sediments is often measured, the concentrations of dissolved organic carbon (DOC) is runoff water is rarely measured. A rainfall simulator study was conducted to determine differences in C-pools in eroded sediments as compared to bulk soil. In addition, concentrations of DOC were measured and compared to DOC losses from the seven watersheds to look at the issue of scaling from plot scale to small and large watershed scales. As part of a larger project, DOC losses from seven experimental watersheds were measured. The watersheds are part of the St. Joseph River basin, and were instrumented to collect runoff into agricultural drainage ditches before water entered creeks and streams. Runoff samples from both the watersheds and the rainfall simulator study were acidified, frozen and transported to the lab for analysis. Carbon concentrations in the runoff from the watersheds were measured in base flows as well as from flows during rainfall events. In one example from the 2004 season, 5-25 g C s-1 were lost from the large experimental watersheds in base flow discharge into the ditch receiving drainage from a 4650 ha watershed. Base flow was almost continuous during early April to mid-November during 2004. This translates to 96,768 to 483,840 kg C loss as DOC during the season from the watershed, or 2-10 g C m2. Data from three years (2003-2005) of DOC measurements from seven watersheds will be presented.

Back to 3.2A Environmental Impacts of Soil Erosion - Measuring and Modeling On- and Off-Site Damages of Soil Erosion - Oral
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Back to The 18th World Congress of Soil Science (July 9-15, 2006)