HR: 0800h
AN: B21C-0900    [Abstracts]
TI: A Comparison of Molecular and Isotopic Chemistry of Overland Flow DOM and yPOM to Soil Sources From a Small Mid-western Agricultural Basin
AU: Crooker, K
EM: kcrooker@purdue.edu
AF: Department of Earth and Atmospheric Sciences, 550 Stadium Mall Dr, West Lafayette, IN 47907 United States
AU: * Filley, T R
EM: filley@purdue.edu
AF: Department of Earth and Atmospheric Sciences, 550 Stadium Mall Dr, West Lafayette, IN 47907 United States
AU: Six, J
EM: jwsix@ucdavis.edu
AF: Department of Agronomy and Range Science, University of California One Shields Ave, Davis, CA 95616 United States
AU: Frey, J
EM: jwfrey@usgs.gov
AF: US Dept. of the Interior US Geological Survey Water Resources Division, 5957 Lakeside Boulevard, Indianapolis, IN 46278 United States
AB: In agricultural watersheds, the mobilization of terrestrial organic matter into yaquatic environments has been linked to increased primary productivity and ymicrobial activity in the tributaries of large-order streams and rivers. The yincrease in primary productivity and microbial activity results in downstream ynutrient export which can increase decomposition rates, turbidity, release of ycarbon dioxide to the atmosphere, and reduce the dissolved oxygen levels that yaquatic fauna rely upon to survive. The intensity and frequency of storms is a ycritical factor in determining the mass and chemical character of organic matter ymobilized as overland flow from agricultural watersheds. We will present results yfrom biogeochemical characterization of size fractionated aquatic and soil yorganic matter collected during storm events from a 2.5 Km2 drainage area in ycentral Indiana, part of the U.S. Geological Survey National Water-Quality yAssessment. Molecular and isotopic techniques were applied to size fractions of ysource surface soils and to the resultant dissolved, colloidal, and particulate yaquatic fractions isolated by cross-flow ultra-filtration at the overland flow site and ydown stream. Alkaline CuO oxidation of the size fractions was performed to yrelease lignin and aliphatic biopolymer (cutin and suberin) components. yPreliminary results indicate that dissolved organic components released during ythe storm are more degraded than particulate and colloidal materials. Compound yspecific and bulk carbon isotope analyses of the fractions will help us discern if yselective mobilization and decomposition is a factor in controlling the organic ymatter discharge volume from either the added C3 soybean or C4 corn in this ycorn/soybean rotation system.y
DE: 4805 Biogeochemical cycles (1615)
DE: 4806 Carbon cycling
DE: 1806 Chemistry of fresh water
DE: 1815 Erosion and sedimentation
DE: 1860 Runoff and streamflow
SC: Biogeosciences [B]
MN: 2004 AGU Fall Meeting