Sediment microstructure and resuspension behavior depend on each other

摘要: The critical shear stress of resuspension and rates erosion for cohesive loosely structured sediments must be obtained by direct measurements since there is no theoretical calculation. An in situ experiment on sediment was performed a shallow lake (Langer See, NE Germany; area = 1.27 km2, zmax 3.8 m) summer 2006 using hydrodynamically calibrated chamber (O 20 cm). Shear velocity (u*) incrementally increased 11 steps (0–2.19 cm s−1) to initiate events. Entrainment (E) suspended particulate matter (ESPM), total P (ETP), chlorophyll (EChl a), soluble reactive (ESRP) were determined mass balance. Two subsequent u* (0.53 s−1 1.48 support the ‘two-layered bed’ model fluffy surface aggregate layer (freshly deposited phytodetritus prone resuspension) an underlying more consolidated biostabilised layer. Patterns ESPM (2–106 g m−2 h−1), ETP (11–532 mg EChl (3–24 μg h−1) revealed maximum TP Chl their vertical logarithmic decrease within 4 mm depth, thickness entrained. advective ESRP flux (17 43 times higher than diffusive SRP (0.4 h−1). micro-profiles suggest that bed formation function both settling (fluff) consolidation (biostabilisation). Thus, microstructure behavior depend each other.