Using dissolved and particulate carbon for the prediction

Abstract Various investigations into soft sediment transport have shown recently that the growth of benthic microorganisms on cohesive sediments can influence the erosional behaviour of the bed material. The formation of biofilms and microbial mats on mud banks has been reported to occur in estuaries and reservoirs. Most benthic microorganisms produce and exudate extracellular polymeric substances (EPS). These exudates serve as connection between cells and sediment particles and form the amorphous biofilm matrix in which the organisms are embedded. A variety of biological parameters (i.e. photopigment content, number of cells) has been used to correlate the biological status of the bed with the erodibility of the sediments. This article deals with the utilization of dissolved and particulate organic carbon to perform this correlation. Experiments were carried out in a small in-situ-device. Biofilms (microbial mats respectively) consisting of pennate diatoms and filamentous cyanobacteria were established on a pure caolinite bed. The shear stress was increased stepwise in order to ascertain the critical shear stress for erosion. Particulate organic carbon (POC) was determined by means of a CHN-elemental analyzer. Dissolved organic carbon (DOC) could be determined using phenol and sulfuric acid.