HR: 14:45h
AN: NB13B-06 [Abstracts]
TI: Biogeochemistry of a California Floodplain Revealed by High Resolution Temporal Sampling
AU: * Gallo, E L
EM: elgallo@ucdavis.edu
AF: University of California, Davis, Dept. of Land, Air and Water Resources
One Shields Ave, Davis, CA 95616 United States
AU: Dahlgren, R A
EM: radahlgren@ucdavis.edu
AF: University of California, Davis, Dept. of Land, Air and Water Resources
One Shields Ave, Davis, CA 95616 United States
AU: Grosholz, E D
EM: tedgrosholz@ucdavis.edu
AF: University of California, Davis, Dept. of Environmental Science and Policy
One Shields Ave, Davis, CA 95616 United States
AU: Ahearn, D
EM: dsahearn@ucdavis.edu
AF: University of California, Davis, Dept. of Land, Air and Water Resources
One Shields Ave, Davis, CA 95616 United States
AB:
Previous weekly monitoring of a floodplain in the California Central Valley confirmed the dynamic spatiotemporal nature of
biogeochemical floodplain processes, but did not resolve short-term (<1 day) temporal dynamics. This study examined water
quality on a fine temporal scale during and after flooding to elucidate short-term variations in biogeochemical processes. In February-March 2004, we collected water samples using autosamplers at the entrance and exit of the floodplain. We detected
diel patterns in chlorophyll-a, with concentrations fluctuating 50% - 200% over 12 hours. Nitrate (NO3--N),
ammonium (NH4+-N) and orthophosphate (PO43--P) concentrations were highest during flooding (0.68 ppm,
0.35 ppm and 101 ppb, respectively). NO3--N and PO43--P decreased 0.12 ppm and 4 ppb per day during
draining and remained constant during ponding; while NH4+-N remained constant during draining and increased 0.02
ppm per day during ponding. Total suspended solids (TSS) were 25% - 65% greater at the entrance than exit; fluctuated
daily with the river hydrograph and decreased while volatile suspended solids increased 9% of TSS per day as hydrologic
residence time increased. Our data demonstrate dramatic floodplain water quality changes occurring over a few hours that
depend on connectivity phase and hydrologic residence time.
DE: 1806 Chemistry of fresh water
DE: 1821 Floods
DE: 1871 Surface water quality
DE: 1890 Wetlands
DE: 9901 NABS Student Award - Basic Research
SC: North American Benthological Society [NB]
MN: 2005 Joint Assembly