Organic matter in bed-sediments of the River Danube and a small unpolluted stream, the Oberer Seebach
Organic matter, the energy base of aquatic ecoystems, was studied in bed-sediments of the 9th order River Danube, near Loiben at river-km 2007. These sediments are well colonized by benthic consumers, and biofilm is a very important compartment of the organic matter. Total organic carbon and total organic nitrogen were measured as the main organic matter parameters. Horizontal and vertical distributions of organic matter as well as grain size distributions were measured. Results from the regulated, polluted and much-used large River Danube are compared with measurements in the unpolluted quasi-natural 2nd order stream Oberer Seebach, where the amount of organic matter is ten times higher. Possible explanations for these large differences are examined. Another comparison is made between an exceptionally silty study area and the sediments of impoundment Altenwörth at river-km 1992.