Resuspension of Sediments from Long Island Sound (U.S.A.)

Abstract

Resuspension experiments were conducted in sea water in an annular flume on fine-grained sediments from Long Island Sound. From these experiments, the resuspension rates and the sediment concentrations at steady-state were quantitatively determined as a function of shear stress and bed compaction. In addition, net resuspension experiments were conducted. From these, the total amount of sediment that could be resuspended at a particular shear stress was determined. In these tests, the resuspension rate decreased with time and the total amount of sediment that could be resuspended at a constant shear stress approached a constant value as time increased. This demonstrates a major difference between the resuspension characteristics of fine-grained sediments and those of uniform-size, coarse-grained, non-cohesive sediments. For the latter case, the resuspension rate ideally would be constant with time. Resuspension experiments were also conducted with deposit-feeding Nucula clams seeded into the sediment bed. In all cases, the steady-state concentrations as a function of shear stress were significantly greater than those in tests without Nucula. The tests also suggest that after sediments are seeded with Nucula for approximately 7 days, the sediment resuspension does not change with time of consolidation.