Fischer, H. Institute of Freshwater Ecology and Inland Fisheries, fischer@igb-berlin.de
Sachse, A. Institute of Freshwater Ecology and Inland Fisheries, sachse@igb-berlin.de
Pusch, M. Institute of Freshwater Ecology and Inland Fisheries, pusch@igb-berlin.de

 
HIGH BACTERIAL PRODUCTION AND DOC RETENTION IN SANDY RIVER SEDIMENTS
 
Bacterial protein production and the retention of DOC in sandy sediments of a eutrophic lowland river were measured using perfused sediment cores. Production was investigated using the 14C-leucine incorporation method. Several DOC-fractions were quantified by size exclusion chromatography followed by IR and UV detection. We found a significant DOC loss after perfusion of the cores with river water, indicating the sediments being a sink for organic carbon. The loss of polysaccharides and other easily degradable substances was higher than that of humic substances. Bacterial protein production was high and amounted to 7.3 ± 2.5 g C cm-3 h-1 in the upper sediment layer. It decreased significantly with increasing sediment depth to 2.3 ± 0.9 g C cm-3 h-1 at 7 cm sediment depth. The loss in total DOC equals only 25 % of the bacterial carbon production. Particulate organic carbon might therefore be the quantitatively more important carbon source for sediment bacteria. We conclude that sandy, unconsolidated bottom sediments may play an important role in river metabolism and self purification by acting as a sink for dissolved and particulate organic carbon.
 
Day: Thursday, Feb. 4
Time: 02:45 - 03:00pm
Location: Sweeney Center
 
Code: SS33TH0245S