The Role of Tep in Estuarine Hydrosedimentary Functioning: Impact on Settling Velocity of Aggregates

Abstract

Transparent exopolymer particles (TEP) are widely recognized to promote sediment aggregation in eutrophic environments. Flocculation in presence of TEP of various suspended sediment concentrations of material sampled on the bank of the Cam River was quantified at the laboratory for turbulence level consistent with slack water and mid ebb conditions measured in the Cam River estuary during dry season of 2009. Stickiness and concentrations of TEP were let to naturally fluctuate by incubation (aging in the dark) for up to nine days. We found that the impact of turbulence on overall buoyancy of TEP-governed aggregation was always opposite between slack water and mid ebb conditions for any duration of incubation; always negative for slack water conditions but for 126 hours of incubation and significantly negative for mid ebb conditions but for 126 hours of incubation. Suspended sediment concentration (SSC) consistently limited aggregates buoyancy, negative or positive. We propose a conceptual model that relates measured and inferred parameters to observed hydrosedimentary processes.