PARENT SESSION
Oral Session #42: Carbon and Nitrogen Cycling. Presiding: S. Hobbie.
Wednesday, August 8, 2001. 8:00 AM to 11:30 AM. Hall of Ideas E.
Specific UV absorbance as an Indicator of DOC source.
Lauster, George1, 1
ABSTRACT- Carbon specific UV absorbance, or SUVA, has been shown to increase with the aromaticity and increasing molecular weight of dissolved organic carbon. Algae, with a few exceptions, rarely produce aromatic compounds unlike land and wetland vegetation. SUVA should therefore provide a useful index of terrestrial and wetland dissolved organic carbon inputs compared to algal dissolved organic carbon inputs to lake surface water. Quarterly measured SUVA values in a suite of seven Wisconsin lakes were related to the position of the lakes in the watershed. Lakes lower in the watershed and more impacted by terrestrial and wetland sources had higher SUVA values. The presence of wetlands areas in the lake caused the greatest increase in SUVA. SUVA values collected biweekly in a eutrophic lake were inversely related to chlorophyll a concentration. Results support use of SUVA as a quick and easy index of changes in DOC supply sources. SUVA may therefore be useful in addressing landscape scale questions on carbon transport, and in-lake ecosystem modeling.
KEY WORDS: organic carbon, lakes