Duff, J. H. U.S. Geological Survey, jhduff@usgs.gov
Aiken, G. H. U.S. Geological Survey,
Jackman, A. P. University of California,
Sheibley, R. W. University of California,
Triska, F. J. U.S. Geological Survey,

 
THE INFLUENCE OF FLUVIAL SYSTEM AND GROUNDWATER DISCHARGE ON DOC CONCENTRATION AND COMPOSITION IN THE SHINGOBEE RIVER, MINNESOTA.
 
The Shingobee River, situated on recently glaciated sediments, interconnects numerous aquatic features including lakes, wetlands, groundwater seeps, and streams. DOC decreases from about 6 mg C/L to 4 mg C/L over a 1400-m long reach that includes channel covered by aquatic macrophytes and algae as well as a large beaver impoundment. Higher stream water than groundwater concentrations and the aromaticity index of stream water DOC suggest that the lakes and wetlands in direct hydrologic connection with the channel are potential DOC sources within the fluvial system. Discharge in the Shingobee River increases significantly downstream due mainly to groundwater discharge along the channel. DOC concentration of groundwater along the channel, both below and adjacent to it, is uniform and low (1 and 2 mg C/L), with an aromaticity index distinctly different from stream water. Close-interval porewater profiles of DOC and other nutrients from hyporheic sediments extending 20 cm below the streambed indicate microbial processing of surface-derived DOC and advection-dispersion of ground water-derived DOC potentially influence stream water DOC concentration. Ongoing efforts to estimate microbial processing and groundwater discharge will better indicate the relative contributions of microbial and hydrologic processes to DOC dynamics.
 
Day: Wednesday, Feb. 3
Time: 03:45 - 04:00pm
Location: Eldorado Hotel
 
Code: CS64WE0345E