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Communication at the NABS Annual meeting, Keystone, 2000
(146) ACETATE STIMULATED DIN REMOVAL IN SEDIMENT PERFUSION CORES FROM
POOL 8, UPPER MISSISSIPPI RIVER BASIN, LA CROSSE, WI:
DENITRIFICATION POTENTIAL.
R.W. Sheibley III1, A.P. Jackman1, J.H. Duff2, F.J. Triska2, E.M. Godsy2, and E. Warren2. 1Department of Chemical Engineering, University of California, Davis, CA 95616, 2U.S. Geological Survey, Water Resources Division, Menlo Park, CA 94025
Sediment cores from two sites in the Upper Mississippi River Basin (UMRB) were perfused to examine DIN removal from river water. Cores from the Root River (a high NO3-, low C tributary) and Running Slough (a low NO3-, high C secondary channel) consisted of 94% sand, 5% silt, and 1% clay. Nitrate and DOC concentrations in the Root River and Running Slough were 3.5 and 1 mg N/L, and 1.5 and 10 mg C/L, respectively. No losses of NO3- between the inlet and outlet of any cores were observed when perfused with river waters, even when they were amended with 10 mg NO3--N/L. However, river water amended with acetate (40 mg C/L) and NO3- stimulated complete DIN removal from both sites. Acetate decreased by 10-20 mg C/L during passage through the cores. Ratios of mg C consumed per mg N ranged from 1.6 to 1.9. We attribute C and N losses to denitrification based on results from preliminary enzyme assays using in situ microcosm incubations. The results of this preliminary study demonstrate potential limitation by metabolically available DOC for DIN removal from the UMRB and tributary in sediments composed primarily of sand.
Presented at 2:45 PM on Tuesday, May 30, 2000 in Nutrient Processes in Sediment
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